Title of Invention	INTERNAL BICYCLE SHIFTER HUB
Abstract	shift key to separate from the clutch member. [ Means of Achievement ] An internal shifter hub 10 comprises a hub axle 21, a driver 22, a slave 23, a power-transmitting mechanism 25, and a switching mechanism 26. The power-transmitting mechanism 25 is disposed in the housing space of the slave, is provided with three power transmission paths (upshift, direct, and downshift), and is designed to transmit motive power from the driver to the slave along any power transmission path. The switching mechanism comprises a cylindrical clutch member 45 provided to the hub axle in a rotatable and axially movable fashion, a pushrod 48 disposed in the guide hole 21a of the hub axle in an axially movable fashion, a shift key 49 mounted in a slot 21b in an axially movable fashion while allowed to come into contact with the tip of the pushrod, a coil spring 60 for urging the clutch member toward the shift key, and a linkage ring 64 for linking the shift key to the clutch member in a rotatable and axially immovable fashion. [ Selected Figure ] Figure 3

Title of Invention

INTERNAL BICYCLE SHIFTER HUB

Abstract

shift key to separate from the clutch member. [ Means of Achievement ] An internal shifter hub 10 comprises a hub axle 21, a driver 22, a slave 23, a power-transmitting mechanism 25, and a switching mechanism 26. The power-transmitting mechanism 25 is disposed in the housing space of the slave, is provided with three power transmission paths (upshift, direct, and downshift), and is designed to transmit motive power from the driver to the slave along any power transmission path. The switching mechanism comprises a cylindrical clutch member 45 provided to the hub axle in a rotatable and axially movable fashion, a pushrod 48 disposed in the guide hole 21a of the hub axle in an axially movable fashion, a shift key 49 mounted in a slot 21b in an axially movable fashion while allowed to come into contact with the tip of the pushrod, a coil spring 60 for urging the clutch member toward the shift key, and a linkage ring 64 for linking the shift key to the clutch member in a rotatable and axially immovable fashion. [ Selected Figure ] Figure 3

Full Text	[ Detailed Description of the Invention ] iDQOl] [ Field of Industrial Utilization ] The present invention relates to an internal shifter hub, and more particularly to an internal bicycle shifter hub that can be mounted on a bicycle frame and that is intended for shifting and outputting motive power at a selected speed ratio from an input unit to an output unit. t-9©03-}— [ Prior Art ] A three-speed internal shifter hub used on a bicycle is fixed to the rear part of the bicycle frame. This internal shifter hub primarily comprises a hub axle fixed to the rear part of the bicycle frame, a driver capable of rotating about the hub axle, a hub shell fitted over the driver, a power-transmitting mechanism having three power transmission paths (upshift, downshift, and direct) and comprising a planetary gear mechanism and a plurality of one-way clutches, and a switching mechanism for switching among the power transmission paths of the power-transmitting mechanism. [0003] - In the hub axle, the central portion is provided with a guide hole extending in the axial direction from one end to the center, and the end portion of the guide hole is provided with a slot going all the way through in the radial direction. The driver is provided with a hub cog (a type of input unit), and motive power is transmitted to the driver from the chainwheel crank through the agency of a chain. The hub shell, which is a cylindrical member having a space in its interior, is provided along the external peripheral portion thereof with hub flanges disposed at a distance in the axial direction and designed for attaching the spokes that constitute the rear wheel (a type of output unit). The planetary gear mechanism comprises a sun gear formed integrally with the hub axle, a cage for rotatably supporting the hub axle, planetary gears rotatably mounted in the cage and caused to mesh with the sun gear, and a gear ring that meshes with the planetary gears. The one-way clutches are disposed between the driver and the gear ring, between the gear ring and the hub shell, and between the cage and the hub shell in order to form three power transmission paths. Of these, the one-way clutch disposed between the gear ring and the hub shell can be alternated between a linked state and a disengaged state by the switching mechanism, and the other one-way clutches are used solely to transmit one-way rotation (rotation in the direction of travel of the bicycle) from the cage to the hub shell or from the driver to the gear ring. The switching mechanism, which is provided to the hub axle while allowed to rotate and move in the axial direction, comprises a cylindrical clutch member for selecting one of the three power transmission paths, a shift rod provided to the guide hole of the hub axle while allowed to move in the axial direction, a shift key designed for moving the clutch element and mounted in the aforementioned slot while allowed to move in the radial direction and to press against the tip of the shift rod, a first urging member for urging the clutch member toward the shift key, and a second urging member for urging the shift key toward the clutch member. +WQ64—_ The clutch element can be moved into one of the following three positions: an upshift position for meshing the driver and the cage and transmitting motive power from the driver to the cage; a direct-link position in which the engagement with the cage is released; and a downshift position in which the link to the cage is released and the one- way clutch for linking the gear ring and the hub shell is disengaged. The shift key is housed inside the clutch member and is allowed to move in the axial direction integrally with the clutch member. The first urging member is designed to move the clutch member in the direction opposite the pushing direction. In addition, the second urging member is designed to cause the shift key to follow the clutch member. Consequently, the first urging member and the second urging member perform urging in opposite directions. In this case, increasing the urging force of the second urging member makes it necessary to further increase the urging force of the first urging member in order to return the clutch member in the direction opposite the pushing direction, and considerable force is thus needed to perform shifting operations. It is therefore preferable for the urging force of the second urging member to be minimal. 40007 ] In a three-speed internal shifter hub thus configured, the clutch member is moved and the shifting operations are performed by pushing the shift rod with a bell crank linked by a shifter cable to a shift lever, shift grip, or other type of shift control. In this case, the clutch member is, for example, in the upshift position, and the driver and the cage are linked to each other by the clutch member when the shift control is not operated. In this state, the cage rotates at the same rotational velocity as the driver, the gear ring is upshifted through the planetary gears, and the motive power of the driver is upshifted and transmitted to the hub shell from the gear ring through a one-way clutch. {-0008 ] Moving the shift control by one click stop pivots the bell crank, pushes the shift rod against the urging force of the first urging member, and moves the clutch member into the direct-link position through the agency of the shift key. When this occurs, the connection between the driver and the cage is released, and the motive power of the driver is directly transmitted to the gear ring through the one-way clutch. The motive power of the driver is transmitted directly from the gear ring to the hub shell through the agency of the one-way clutch. £-0009 I Moving the shift control by another click stop further pivots the bell crank, pushes the shift rod, and moves the clutch member into the deepest downshift position through the agency of the shift key. When this occurs, the one-way clutch for connecting the gear ring and the hub shell is disengaged by the clutch member, and the motive power of the driver is downshifted by being transmitted from the gear ring to the cage through the agency of the one-way clutch. The motive power of the driver is downshifted and transmitted from the cage to the hub shell through the agency of the one-way clutch. Every time the shift control is moved back one click stop, the clutch member is urged by the first urging member and is moved one step in the direction closer to the cage. [ Problems Which the Invention Is Intended to Solve ] In the above-described three-speed internal shifter hub, the clutch member is sometimes disengaged from the cage against the urging force of the first urging member when the driver rotates in a state of slight meshing between the clutch member and the cage. In such cases, the shift key sometimes disengages from the clutch member without following it because of the weak urging force of the second urging member. Disengagement of the shift key from the clutch member creates the risk that the shift key will be tilted and rendered incapable of pushing the clutch member any longer. .[0012] ■ The urging force of the second urging member can be increased in order to prevent this phenomenon. Increasing the urging force of the second urging member makes it necessary, however, for the first urging member to have a fairly strong urging force. When the urging force of the first urging member is increased, the shift control must be moved against the urging force thereof, thus increasing the force needed to perform the above-described shifting operations and impairing shifting. 4 0013] , An object of the present invention is to ensure that shifting can be performed with reduced force and that the shift key is rendered less prone to disengagement from the clutch member in a three-speed internal shifter hub. [ Means Used to Solve the Above-Mentioned Problems ] The internal bicycle shifter hub pertaining to invention 1 can be mounted on a bicycle frame and is configured such that motive power from an input unit is changed in speed by upshifting, direct linkage, or downshifting, and is transmitted to an output unit by the operation of a shift control. The hub comprises a hub axle, a driver, a slave, a power-transmitting mechanism, and a switching mechanism. The hub axle is one in which the central portion is provided with a guide hole extending in the axial direction from one end to the center, in which the end portion of the guide hole is provided with an axially extending slot that goes all the way through in the radial direction, and which can be fixed on the frame, The driver is rotatably supported on the hub axle and can be linked to the input unit. The slave is a cylindrical element that has a storage space inside, is rotatably supported on the hub axle, and is linkable to the output unit. The power-transmitting mechanism is a mechanism that is disposed in the storage space of the slave, is provided with three power transmission paths (upshift path, direct-link path, and downshift path), and is designed to transmit the motive power from the driver to the slave along any of the power transmission paths. The switching mechanism is a mechanism comprising a cylindrical clutch member that is provided to the hub axle in a rotatable and axially movable fashion and that is designed to select any of the three power transmission paths, a shift rod that is disposed in the guide hole of the hub axle in an axially movable fashion and that is positioned at three axial positions (first position, second position, and third position) by the operation of the shift control, a shift key that is mounted in the slot in an axially movable fashion while allowed to come into contact with the tip of the shift rod and that is used to move the clutch member, an urging member for urging the clutch member toward the shift key, and a link member for linking the shift key to the clutch member in a rotatable and substantially axially immovable fashion; the switching mechanism being designed to switch the power transmission path in the power-transmitting mechanism by the axial movement of the clutch member. [ QQ15_] In the internal bicycle shifter hub, the power transmission path is made, for example, into an upshift path by the clutch member when the nonrotatable shift rod housed in the guide hole inside the hub axle is positioned at the first position. Pushed by the shift rod, the shift key moves inside the slot, urging the clutch member in the axial direction, and the clutch member switches the power transmission path, for example, to the direct-link position, when the shift control is actuated and the shift rod is moved to one side in the axial direction inside the guide hole, reaching the second position. Furthermore, the clutch member switches the power transmission path, for example, to the downshift path when the shift rod is moved to the third position and the clutch member is moved further in the axial direction. The clutch member, urged by the urging member, switches the power transmission path to the direct-link position when the shift rod is moved in this state by the shift control to the other side in the axial direction and is returned to the second position. Urged by the urging member, the clutch member switches the power transmission path to the upshift position when the shift rod is returned to the first position. Here, the shift key can move together with the clutch member because the shift key is linked by a link member to the clutch member in an axially immovable fashion when for some reason the clutch member displays a tendency to move to one side in the axial direction. Consequently, the shift key is unlikely to separate from the clutch member. In addition, dispensing with the need to provide a member for urging the shift key toward the clutch member makes it possible to reduce the urging force of the urging member, and thus to reduce the force needed to operate the shift control for pressing the shift rod against the urging force of the urging member and to shift gears with light force. The internal bicycle shifter hub pertaining to invention 2 is such that the power-transmitting mechanism in the hub set forth in invention 1 comprises a planetary gear y mechanism comprising a sun gear disposed concentrically with the hub axle and formed integrally with the hub axle, a cage fitted over the hub axle and rotatably supported by the hub axle, planetary gears rotatably mounted in the cage and caused to mesh with the sun gear, and a gear ring that meshes with the planetary gears; a first one-way clutch for linking the driver and the gear ring; a second one-way clutch designed to link the gear ring with the slave and alternated between a linked state and a disengaged state by the clutch member; and a third one-way clutch for linking the cage and the slave; with the clutch member moving into an upshift position in which the driver and the cage are linked to each other and the second one-way clutch is brought into a linked state when the shift rod is positioned at the first position, into a direct-link position in which the link between the driver and the case is released and the second one-way clutch is brought into a linked state when the shift rod is positioned at the second position, and into an upshift position in which the link between the driver and the case is released and the second one- way clutch is brought into a disengaged state when the shift rod is positioned at the third position. j-QGW-l In this case, the clutch member links the driver and the case to each other and converts the second one-way clutch to a linked configuration when the shift rod reaches the first position, the clutch member is moved to the upshift position, and the upshift path is selected. As a result, the motive power of the driver is transmitted first from the clutch member to the cage, and then to the slave via the planetary gear, gear ring, and second one-way clutch, driving the slave at a higher speed. ~[0Q18 j— The clutch member releases the link between the cage and the driver and converts the second one-way clutch to a linked configuration when the shift rod reaches the second position and the clutch member selects the direct-link path. The motive power of the driver is therefore transmitted to the slave via the first one-way clutch, gear ring, and second one-way clutch, and the slave is driven through a direct link. The link between the driver and the case is released and the second one-way clutch is brought into a disengaged position when the shift rod reaches the third position and the clutch member selects the downshift path. The motive power of the driver is therefore transmitted to the gear ring via the first one-way clutch. At this time, the second one-way clutch has a disengaged configuration, so the motive power transmitted to the gear ring is transmitted to the slave via the planetary gears, cage, and third one-way clutch without being transmitted to the slave, and the slave is driven at a reduced speed. ■ [0019]- If motive power is transmitted while the linkage between the clutch member and the cage is inadequate when the shift rod is in the first position, the clutch member sometimes moves in the axial direction against the urging force of the urging member, separating from the cage. Even in such cases, however, the shift key is linked by the link member to the clutch member while prevented from moving in the axial direction, so the shift key moves with the clutch member in interlocked fashion and is unlikely to separate from the clutch member. f0020 J The internal bicycle shifter hub pertaining to invention 3 is such that the clutch member in the hub set forth in invention 1 or 2 is provided with an interior storage space capable of accommodating the shift key in a rotatable and axially movable fashion; and the link member links the shift key housed in the storage space to the clutch member in a rotatable and substantially axially immovable fashion. In this case, the shift key is unlikely to separate from the clutch member because this shift key is housed in the storage space formed in the clutch member. The internal bicycle shifter hub pertaining to invention 4 is such that the shift key in the hub set forth in invention 3 is a bar-shaped member whose length is sufficient to allow both ends thereof to extend from the slot and in which the two end surfaces face the inner peripheral surface of the storage space in the clutch member, and the link member is a ring member engagedly disposed between the clutch member and the shift key. In this case, the clutch member and the shift key can remain connected even when they rotate relative to each other because the clutch member and the shift key are liked together by the ring member. ,[ 002? ] The internal bicycle shifter hub pertaining to invention 5 is such that, in the hub set forth in invention 4, an annular groove is formed in the inner peripheral surface of the storage space, a long groove capable of facing the annular groove is formed in the two end surfaces facing the inner peripheral surface of the shift key, and the link member is a ring-shaped spring member that has ends and can be secured in the annular groove and long groove. In this case, the link member is a ring-shaped elastic spring member that has ends, so when the shift key is mounted in the storage space of the clutch member, such mounting allows the link member to expand in the radial direction even when this member is mounted in the annular groove in advance. When the shift key is mounted in a mounting position that faces both grooves, the link member is compressed until the two members are locked in place in the two grooves. Mounting of the shift key is therefore facilitated. The internal bicycle shifter hub pertaining to invention 6 is such that, in the hub set forth in invention 5, the inside diameter of the annular groove is greater than the outside diameter of the link member in a free state. In this case, the link member can easily expand in the annular groove when the shift key is mounted in the clutch member. The internal bicycle shifter hub pertaining to invention 7 is such that, in the hub set forth in invention 5 or 6, the axial length of the long groove is greater than the thickness of the link member. In this case, the axial length of the long groove is greater than the thickness of the link member, a gap is formed between the link member and the long groove, and the clutch member can rotate smoothly when this member rotates in relation to the shift key. The rolling efficiency of the hub is thus unlikely to decrease. Accordingly the present invention provides a bicycle hub transmission comprising: an axle; a driving member rotatably ported on the axle; a slave rotatably supported on the axle; a power transmitting mechanism disposed between the driving member and the slave for communicating rotational force from the driving member to the slave through a plurality of power transmitting paths; a clutch member rotatably supported and axially movable on the axle for selecting one of the plurality of power transmitting paths of the power transmitting mechanism; a shift key for moving the clutch member axially; a shift rod axially movably supported to the axle for moving the shift key axially; a biasing mechanism for biasing the clutch member toward the shift key; and a link for linking the clutch member to the shift key so that the clutch member is substantially axially immovable relative to the shift key. With reference to the accompanying drawings in which: In Fig. 1, the bicycle obtained by adopting an embodiment of the present invention is a recreational bicycle that comprises a frame 1 composed of a double-loop- shaped frame body 2 and a front fork 3, a handle component 4, a driver unit 5, a front wheel 6, a rear wheel 7 provided with a three-speed internal shifter hub 10, a front brake device 8, and a shift control 9 for the convenient operation of the internal shifter hub 10. Components such as a saddle 11, the handle component 4, the front wheel 6, and the rear wheel 7 are mounted on the frame 1. The handle component 4 has a handle stem 14 that is fixed to the top of the front fork 3, and a handlebar 15 that is fixed to the handle stem 14. A brake lever 16, a grip 17, and the shift control 9, which constitute the front brake device 8, are mounted on the right end of the handlebar 15. The shift control 9 is mounted on the handlebar 15 inside the brake lever 16, and is linked to the internal shifter hub 10 by a shift control cable 73 comprising an inner cable and an outer casing. The shift control 9 has a common structure comprising a winding lever for taking up and actuating the inner cable, and a release lever for disabling the winding action of the winding lever and paying out the inner cable. A detailed description will therefore be omitted. tfcflQ2&^ The driver unit 5 has a chainwheel 18 mounted in the lower portion (bottom bracket) of the frame body 2. The motive power of the chainwheel 18 is transmitted to the internal shifter hub 10 by a chain 19 wound around the chainwheel 18. [ Structure of Internal Shifter Hub ] The internal shifter hub 10 is a three-speed hub. As shown in Fig. 2, this internal shifter hub 10 comprises a hub axle 21 fixed in the rear forks (not shown) of the bicycle frame 2, a driver 22 fitted over one end of the hub axle 21, a hub shell (a type of slave) 23 that is disposed farther outward around the outside of the hub axle 21 and the driver 22, a power-transmitting mechanism 25 containing a planetary gear mechanism 24, a switching mechanism 26 for selecting the power transmission path, and a bell crank 27 for actuating the switching mechanism 26. PJUJX / J The hub axle 21 is a bar-shaped member with a large-diameter central portion, two small-diameter end portions, and threads at both ends. A guide hole 21a extending from the left end to the central portion in Fig. 2 is provided in the central core portion of the hub axle 21. A slot 21b going all the way through the central core of the hub axle 21 is provided along the central core at a prescribed distance. One side of the driver 22 is rotatably supported on the hub axle 21 by balls 30 and a hub cone 31, and a hub cog 32 is fitted over one end. In addition, a plurality of inner serration teeth 22a are formed in the axial direction in the inner peripheral portion of the driver 22 at the other end. The hub shell 23 is a cylindrical member, and the housing space 23 a along the inner peripheral portion thereof accommodates the driver 22 and the power-transmitting mechanism 25. The hub shell 23 can rotate about the hub axle 21 through the agency of a hub cone 35 and balls 33 and 34. Hub flanges 36 and 37 for supporting spokes 7a (see Fig. 1) are fixed to both ends of the outer peripheral portion of the hub shell 23. [ Structure of Power-Transmitting Mechanism ] The power-transmitting mechanism 25 comprises three one-way clutches 50-52 in addition to the planetary gear mechanism 24, and has the three power transmission paths (upshift, direct, and downshift) described below. The planetary gear mechanism 24 comprises a sun gear 40 formed concentrically to and integrally with the hub axle 21, a gear cage 41 fitted over the hub axle 21, four planetary gears 42 (only two planetary gears are shown in the drawing) meshed with the sun gear 40, and a gear ring 43. r nmn i The gear cage 41 is a cylindrical member rotatably supported by the hub axle 21. The gear cage 41 is provided with four notches 41a in the circumferential direction, and a planetary gear 42 is rotatably supported by a pin 44 in each of the notches 41a. Inner serration teeth 41b are formed in the inner peripheral portion at one end of the gear cage 41. The gear ring 43 is a cylindrical member extending from the planetary gears 42 to the outer periphery of the driver 22. An inner-tooth gear 43b is formed in the inner peripheral portion at the other end of the gear ring 43. The planetary gears 42 mesh with the planetary gear 40 and at the same time with the inner-tooth gear 43b of the gear ring 43 in the manner described above. A first one-way clutch 50 is mounted between the driver 22 and the gear ring 43. The first one-way clutch 50 is a pawl-type, one-way clutch for transmitting only the rotational motive power of the driver 22 to the gear ring 43 in the direction of travel. In addition, notches 43a are formed at two facing locations at one end of the gear ring 43, and a clutch pawl 53 constituting a second one-way clutch 51 is pivotably supported by a pin 54 in the notches 43a. The clutch pawl 53 is urged in the upright direction (toward the linked state) by a helical torsion spring 55 wound around the outside of the pin 54. When the second one-way clutch 51 is in the linked state, only the motive power of rotation in the direction of travel is transmitted from the gear ring 43 to the hub shell 23. It is only when the gear ring 43 rotates in the direction of travel that the clutch pawl 53 meshes with the ratchet teeth 23b formed on the inner peripheral surface of the hub shell 23. The second one-way clutch 51 can alternate between a disengaged state (in which the clutch pawl 53 is retracted from the ratchet teeth 23b) and a linked state (in which the clutch pawl 53 is caused to mesh with the ratchet teeth 23b by the movement of the below-described clutch member) even when the gear ring 43 is in a state in which rotation can be transmitted in the direction of travel. [.firm ] A third one-way clutch 52 for transmitting only the motive power of rotation in the direction of travel from the gear cage 41 to the hub shell 23 is disposed between the gear cage 41 and the hub shell 23. Such a power-transmitting mechanism 25, which comprises a planetary gear mechanism 24 and one-way clutches 50-52, also has the following: an upshift path composed of a driver 22, a clutch member 45 (described below), a gear cage 41, a planetary gear mechanism 24, a gear ring 43, a second one-way clutch 51, and a hub shell 23; a direct-link path composed of a driver 22, a first one-way clutch 50, a gear ring 43, a second one-way clutch 51, and a hub shell 23; and a downshift path composed of a driver 22, a first one-way clutch 50, a gear ring 43, a planetary gear mechanism 24, a gear cage 41, a third one-way clutch 52, and a hub shell 23. 40033-} [ Structure of Switching Mechanism ] The switching mechanism 26, which is designed to select one of the three power transmission paths, comprises a clutch member 45 and a clutch actuator 46. The clutch member 45 switches the driver 22 and the gear cage 41 between a linked state and a disengaged state, and switches the second one-way clutch 51 between a linked state and a disengaged state. The clutch member 45 is fitted over the hub axle 21 while allowed to move and rotate in the axial direction. The clutch member 45 is a cylindrical member (as shown in Fig. 4); outer serration teeth 45a are formed in the outer peripheral portion at one end of the member; and these outer serration teeth 45a are slidably engaged with the inner serration teeth 22a of the driver 22. In addition, a large-diameter portion 45b is formed on the other end of the clutch member 45, and outer serration teeth 45c are formed in the outer peripheral portion of the member. The outer serration teeth 45c can engage the inner serration teeth 41b formed in the gear cage 41. A tapered surface 45d is formed between the large-diameter portion 45b and one end. This tapered surface 45d is designed to tip the clutch pawl 53 of the second one-way clutch 51 from a linked state (shown by the solid line) into a disengaged state (shown by the broken line in the form of alternate long and two short dashes). When the clutch member 45 moves from the left side toward the downshift position at the right end, the clutch pawl 53 slides along the tapered surface 45d, rises on the large-diameter portion 45b, and assumes the disengaged state. The clutch member 45 is urged toward the gear cage 41 by a coil spring 60. 4=30344- A storage space 62 is formed along the inner periphery of the clutch member 45, and an annular groove 63 is formed in the inner peripheral surface thereof, as shown in Fig. 3. The clutch actuator 46 is designed to move the clutch member 45 in the axial direction of the hub axle 21. The clutch actuator 46 comprises a pushrod 48 that moves in the axial direction inside the guide hole 21a, and a shift key 49 pushed by the pushrod 48 toward the clutch member 45, as shown in Fig. 1.' 4-0035].. The pushrod 48 is a bar-shaped member whose length is greater than the distance between the left end of the hub axle 21 and the right end of the slot 21b. The shift key 49 is a member shaped as a square bar moving in the axial direction inside the slot 21b when pushed, as shown in Fig. 3. The shift key 49 is rotatably disposed in the storage space 62 of the clutch member 45 while prevented from moving in the axial direction. The two ends of the shift key 49 extend in the radial direction from the hub axle 21 and are capable of coming into contact with the stepped portions 45e of the clutch member 45. A long groove 49b capable of facing the annular groove 63 is formed in the two end faces 49a of the shift key 49 facing the inner peripheral surface 62a of the storage space 62 of the clutch member 45. The long groove 49b and the annular groove 63 accommodate a linkage ring 64, which is confined between the two grooves. The linkage ring 64 is designed to link the shift key 49 with the clutch member 45 in a rotatable and axially immovable fashion. The linkage ring 64 is shaped by bending an elastic wire rod into a circular shape, the two end portions of which are slightly separated from each other. In a free state, the outside diameter of the linkage ring 64 is slightly less than the inside diameter of the annular groove 63. The linkage ring 64 can therefore expand in the radial direction when mounted in the annular groove 63. In addition, the length (width) of the long groove 49b in the direction of the hub axle is greater than the wire diameter of the linkage ring 64. The reason is to allow the clutch member 45 to rotate smoothly when this clutch member rotates in relation to the shift key 49. t-0037] [ Structure of Bell Crank ] The bell crank 27 is mounted on the left end of the hub axle 21. The bell crank 27 comprises a support bracket 70 mounted on the axle end, and a link member 71 pivotably supported by the support bracket 70. The outer casing 73a of the shift control cable 73 is attached to the support bracket 70, and the inner cable 73b is attached to the link member 71. The tip of the link member 71 is pressed against the base end of the pushrod 48. With this arrangement, the link member 71 is pivoted by pulling the inner cable 73b with the aid of the shift control 9, whereupon the pushrod 48 is pushed, the clutch member 45 is pushed by the shift key 49, and a lower speed is selected. On the other hand, loosening the inner cable causes the coil spring 60 to push the clutch member 45, and a higher speed to be selected. [ Shifting Operations ] A shifting operation is performed by actuating the pushrod 48 with the bell crank 27 through the agency of the shift control cable 73.. [ Shifting From Higher Speed to Lower Speed ] In the state shown in Fig. 2, in which the pushrod 48 has not been pushed in, the clutch member 45 is disposed in the upshift position at the left end, and the motive power from the driver 22 is upshifted through the upshift path and transmitted to the hub shell 23. In this state, the second one-way clutch 51 is in a linked state, so motive power is transmitted from the driver 22 to the gear cage 41 via the clutch member 45, and the motive power transmitted to the gear cage 41 is further transmitted to the hub shell 2.3 via the planetary gear mechanism 24, gear ring 43, and second one-way clutch 51. In this case, input rotation is upshifted and output at a speed ratio determined by the number of teeth on the sun gear 40, planetary gears 42, and gear ring 43. When an attempt is made in this case to transmit rotation from the driver 22 in the direction of the gear ring 43 via the first one-way clutch 50, no rotation is transmitted from the first one-way clutch 50 because the gear ring 43 rotates faster than the driver 22. Actuating the winding lever of the shift control 9 pivots the link member 71 of the bell crank 27 and pushes the pushrod 48 one step inward. As a result, the shift key 49 is pushed by the link member 71 through the agency of the pushrod 48 against the spring force of the coil spring 60, and is moved to the right in Fig. 3 while guided along the slot 21b. In the process, the clutch member 45 is also pushed and moved to the right, reaching the direct-link position shown by the broken line (alternate long and two short dashes) in Fig. 4, whereby the motive power of the driver 22 is transmitted to the hub shell 23 along the direct-link path. When the clutch member 45 reaches the direct-link position, the gear cage 41 and the driver 22 are no longer linked by the clutch member 45. In this state as well, only the rotation in the direction of travel can be transmitted to the hub shell 23 from the gear ring 43 because the second one-way clutch 51 is in a linked state. Specifically, the rotation that has been input to the driver 22 is transmitted to the gear ring 43 via the first one-way clutch 50 and then to the hub shell 23 via the second one-way clutch 51, and the rotation of the driver 22 is directly transmitted to the hub shell 23 via the gear ring 43. At this time, the rotation is transmitted from the gear ring 43 to the gear cage 41 via the planetary gear mechanism 24, and the gear cage 41 is rotated at a lower speed, but because the hub shell 23 rotates faster than the gear cage 41, there is no transmission of rotation from the gear cage 41 to the hub shell 23 via the third one-way clutch 52. f Pin in l vr^M\m I J When the winding lever of the shift control 9 is actuated from its direct-link state and the pushrod 48 is pushed in even further, the shift key 49 moves further to the right, and the clutch member 45 is moved in accordance with this to the downshift position shown by the dashed line in Fig. 4. As a result, the clutch pawl 53 of the second one-way clutch 51 is swung into the disengaged state by the tapered surface 45d, and the link between the gear ring 43 and the hub shell 23 is released. The motive power from the driver 22 is therefore transmitted to the hub shell 23 along the downshift path. Specifically, the motive power that has been input to the driver 22 is transmitted to the gear ring 43 via a first one-way clutch 50. The rotation transmitted to the gear ring 43 is further transmitted to the hub shell 23 via the planetary gear mechanism 24, gear cage 41, and third one-way clutch 52. In this case, the input rotation is downshifted and output at a speed ratio determined by the number of teeth on the sun gear 40, planetary gears 42, and gear ring 43. [ SlufUngJFrom Lower Speed to Higher Speed ] If the release lever is actuated by the shift control 9 in a downshift state, the link member 71 of the bell crank 27 is retracted, the shift key 49 is pushed by the clutch member 45 (which is, in turn, pushed by the coil spring 60), and the pushrod 48 is pushed as well. The clutch member 45 is brought to a direct-link position. When this happens, the clutch member 45 is separated from the clutch pawl 53 of the second one-way clutch 51, and the clutch pawl 53 is returned to a linked state by the urging force of the helical torsion spring 55. As a result, the motive power of the driver 22 is directly transmitted to the hub shell 23 along the direct-link path described above. •K)04?,} Further operation of the release lever causes the link member 71 of the bell crank 27 to retract even further, the shift key 49 is further pushed by the clutch member 45 (which is, in turn, pushed by the coil spring 60), and the pushrod 48 is pushed as well. The clutch member 45 is moved to the upshift position, meshing is achieved between the outer serration teeth 45c of the clutch member 45 and the inner serration teeth 41b of the gear cage 41, and the driver 22 and the gear cage 41 are linked to each other. The clutch member 45 sometimes disengages from the gear cage 41 when meshing is inadequate during linkage. Even in such cases, the shift key 49 is linked to the clutch member 45 by the linkage ring 64, making it unlikely that the shift key 49 will separate from the clutch member 45. [ Other Embodiments ] (a) Although the above embodiment was described with reference to a link member shaped as an elastic linkage ring 64 that had ends, the shape of the link member is not limited to the above-described embodiment and can have any configuration in which the shift key 49 is linked to the clutch member 45 in a rotatable and axiaily immovable fashion. As shown, for example, in Fig. 5, it is possible to press-fit a ring- shaped link member 74 into the end portion of the inner peripheral surface of the clutch member 45 and to link the shift key 49 in an axiaily immovable fashion. There is no need in this case to provide the clutch member 45 with an annular groove. Alternately, a groove may be formed in the end portion of the inner peripheral surface of the clutch member 45, and a ring-shaped link member 84 composed of an O-ring or a spring may be mounted therein, as shown in Fig. 6. It is also possible to form the link member as a C-type retaining ring, an E-type retaining ring, or another type of snap ring. [-QQ11 K (b) Although the above-described embodiment pertained to a case in which a shift key 49 was housed in a clutch member 45, there is no need for the shift key to be housed in the clutch member as long as this key can be pressed against the clutch member. (c) Although the aforementioned embodiment was described with reference to an internal shifter hub in which a pushrod 48 was inserted through the left end of the hub axle 21, the present invention is also applicable to an internal shifter hub in which the pushrod 48 is inserted through the right end. [ Merits of the Invention ] According to the present invention, the shift key can move together with the clutch member because the shift key is linked by a link member to the clutch member in an axiaily immovable fashion when for some reason the clutch member displays a tendency to move to one side in the axial direction. Consequently, the shift key is unlikely to separate from the clutch member. In addition, dispensing with the need to provide a member for urging the shift key toward the clutch member makes it possible to reduce the urging force of the urging member, and thus to reduce the force needed to operate the shift control for pressing, the shift rod against the urging force of the urging member and to shift gears with light force. [ Brief Description of the Drawings ] [ Figure 1 ] A side view of a bicycle obtained by adopting an embodiment of the present invention. [ Figure 2 ] A cross section of an internal shifter hub. [ Figure 3 ] An enlarged fragmentary cross section thereof. [ Figure 4 ] An enlarged fragmentary perspective view thereof. [ Figure 5 ] A cross-sectional diagram depicting the structure of a clutch member pertaining to another embodiment. [ Figure 6 ] A cross-sectional diagram depicting the structure of a clutch member pertaining to another embodiment. [ Key to Symbols ] 2: frame, 9: shift control, 10: internal shifter hub, 21: hub axle, 21a: guide hole, 21b: slot, 22: driver, 23: slave, 24: planetary gear mechanism, 25: power-transmitting mechanism, 26: switching mechanism, 40: sun gear, 41: gear cage, 42: planetary gear, 43: gear ring, 45: clutch member, 48: pushrod, 49: shift key, 49b: long groove, 50: first one-way clutch, 51: second one-way clutch, 52: third one-way clutch, 63: annular groove, 64: linkage ring WE CLAIM: 1. A bicycle hub transmission comprising: an axle; a driving member rotatably ported on the axle; a slave rotatably supported on the axle; a power transmitting mechanism disposed between the driving member and the slave for communicating rotational force from the driving member to the slave through a plurality of power transmitting paths; a clutch member rotatably supported and axially movable on the axle for selecting one of the plurality of power transmitting paths of the power transmitting mechanism; a shift key for moving the clutch member axially; a shift rod axially movably supported to the axle for moving the shift key axially; a biasing mechanism for biasing the clutch member toward the shift key; and a link for linking the clutch member to the shift key so that the clutch member is substantially axially immovable relative to the shift key. 2. The bicycle hub transmission as claimed in claim 1 wherein the axle has an axially extending guide hole, and wherein the shift rod is disposed in the guide hole. 3. The bicycle hub transmission as claimed in claim 2 wherein the guide hole is centrally disposed in the axle. 4. The bicycle hub transmission as claimed in claim 2 wherein the axle has a slot extending diametrically through the axle, and wherein the shift key is disposed in the slot and extends radially outwardly from the axle. 5. The bicycle hub transmission as claimed in claim 1 wherein the clutch member comprises an interior storage space, and wherein the shift key is disposed within the interior storage space. 6. The bicycle hub transmission as claimed in claim 5 wherein the clutch member has a tubular shape. 7. The bicycle hub transmission as claimed in claim 5 wherein the shift key has an end face that faces an inner peripheral surface of the clutch member. 8. The bicycle hub transmission as claimed in claim 7 wherein the link comprises a ring engaged between the shift key and the clutch member. 9. The bicycle hub transmission as claimed in claim 8 wherein the inner peripheral surface of the clutch member has a clutch member groove, wherein the end face of the shift key has a shift key groove, and wherein the ring is disposed in the clutch member groove and in the shift key groove. 10. The bicycle hub transmission as claimed in claim 9 wherein an axial length of the shift key groove is greater than an axial thickness of the ring. 11. The bicycle hub transmission as claimed in claim 1 wherein the power transmitting mechanism comprises: a sun gear concentrically disposed around the axle; a cage rotatably supported around the axle; a planet gear rotatably supported to the cage and meshing with the sun gear; and a ring gear rotatably supported around the axle and meshing with the planet gear. 12. The bicycle hub transmission as claimed in claim 11 wherein it comprises a first one-way transmission for linking the driving member to the ring gear; a second one-way clutch for linking the ring gear to the slave; and a third one-way clutch for linking the cage to the slave. 13. The bicycle hub transmission as claimed in claim 12 wherein the clutch member moves to an upshift position for linking the driving member to the cage and allowing the second one-way clutch to link the ring gear to the slave, wherein the clutch member moves to a direct-drive position for disengaging the driving member from the cage and allowing the second one-way clutch to link the ring gear to the slave, and wherein the clutch member moves to a downshift position for disengaging the driving member from the cage and disengaging the second one-way clutch to thereby disengage the ring gear from the slave. 14. The bicycle hub transmission as claimed in claim 11 wherein the axle has a centrally disposed and axially extending guide hole that communicates with a slot that extends diametrically through the axle and forms openings on opposite radial sides of the axle, wherein the shift rod is disposed in the guide hole, and wherein the shift key is disposed in the slot and extends radially outwardly from the opposite radial sides of the axle.

Full Text

[ Detailed Description of the Invention ]
iDQOl]
[ Field of Industrial Utilization ]
The present invention relates to an internal shifter hub, and more particularly to an internal bicycle shifter hub that can be mounted on a bicycle frame and that is intended for shifting and outputting motive power at a selected speed ratio from an input unit to an output unit.
t-9©03-}— [ Prior Art ]
A three-speed internal shifter hub used on a bicycle is fixed to the rear part of the bicycle frame. This internal shifter hub primarily comprises a hub axle fixed to the rear part of the bicycle frame, a driver capable of rotating about the hub axle, a hub shell fitted over the driver, a power-transmitting mechanism having three power transmission paths (upshift, downshift, and direct) and comprising a planetary gear mechanism and a plurality of one-way clutches, and a switching mechanism for switching among the power transmission paths of the power-transmitting mechanism.
[0003] -
In the hub axle, the central portion is provided with a guide hole extending in the axial direction from one end to the center, and the end portion of the guide hole is

provided with a slot going all the way through in the radial direction. The driver is provided with a hub cog (a type of input unit), and motive power is transmitted to the driver from the chainwheel crank through the agency of a chain. The hub shell, which is a cylindrical member having a space in its interior, is provided along the external peripheral portion thereof with hub flanges disposed at a distance in the axial direction and designed for attaching the spokes that constitute the rear wheel (a type of output unit).
The planetary gear mechanism comprises a sun gear formed integrally with the hub axle, a cage for rotatably supporting the hub axle, planetary gears rotatably mounted in the cage and caused to mesh with the sun gear, and a gear ring that meshes with the planetary gears. The one-way clutches are disposed between the driver and the gear ring, between the gear ring and the hub shell, and between the cage and the hub shell in order to form three power transmission paths. Of these, the one-way clutch disposed between the gear ring and the hub shell can be alternated between a linked state and a disengaged state by the switching mechanism, and the other one-way clutches are used solely to transmit one-way rotation (rotation in the direction of travel of the bicycle) from the cage to the hub shell or from the driver to the gear ring.
The switching mechanism, which is provided to the hub axle while allowed to rotate and move in the axial direction, comprises a cylindrical clutch member for selecting one of the three power transmission paths, a shift rod provided to the guide hole of the hub axle while allowed to move in the axial direction, a shift key designed for moving the clutch element and mounted in the aforementioned slot while allowed to move in the radial direction and to press against the tip of the shift rod, a first urging member for urging the clutch member toward the shift key, and a second urging member for urging the shift key toward the clutch member.
+WQ64—_
The clutch element can be moved into one of the following three positions: an upshift position for meshing the driver and the cage and transmitting motive power from the driver to the cage; a direct-link position in which the engagement with the cage is released; and a downshift position in which the link to the cage is released and the one-

way clutch for linking the gear ring and the hub shell is disengaged. The shift key is housed inside the clutch member and is allowed to move in the axial direction integrally with the clutch member. The first urging member is designed to move the clutch member in the direction opposite the pushing direction. In addition, the second urging member is designed to cause the shift key to follow the clutch member. Consequently, the first urging member and the second urging member perform urging in opposite directions. In this case, increasing the urging force of the second urging member makes it necessary to further increase the urging force of the first urging member in order to return the clutch member in the direction opposite the pushing direction, and considerable force is thus needed to perform shifting operations. It is therefore preferable for the urging force of the second urging member to be minimal.
40007 ]
In a three-speed internal shifter hub thus configured, the clutch member is moved and the shifting operations are performed by pushing the shift rod with a bell crank linked by a shifter cable to a shift lever, shift grip, or other type of shift control.
In this case, the clutch member is, for example, in the upshift position, and the driver and the cage are linked to each other by the clutch member when the shift control is not operated. In this state, the cage rotates at the same rotational velocity as the driver, the gear ring is upshifted through the planetary gears, and the motive power of the driver is upshifted and transmitted to the hub shell from the gear ring through a one-way clutch.
{-0008 ]
Moving the shift control by one click stop pivots the bell crank, pushes the shift rod against the urging force of the first urging member, and moves the clutch member into the direct-link position through the agency of the shift key. When this occurs, the connection between the driver and the cage is released, and the motive power of the driver is directly transmitted to the gear ring through the one-way clutch. The motive power of the driver is transmitted directly from the gear ring to the hub shell through the agency of the one-way clutch.
£-0009 I
Moving the shift control by another click stop further pivots the bell crank, pushes the shift rod, and moves the clutch member into the deepest downshift position through

the agency of the shift key. When this occurs, the one-way clutch for connecting the gear ring and the hub shell is disengaged by the clutch member, and the motive power of the driver is downshifted by being transmitted from the gear ring to the cage through the agency of the one-way clutch. The motive power of the driver is downshifted and transmitted from the cage to the hub shell through the agency of the one-way clutch.
Every time the shift control is moved back one click stop, the clutch member is urged by the first urging member and is moved one step in the direction closer to the cage.
[ Problems Which the Invention Is Intended to Solve ]
In the above-described three-speed internal shifter hub, the clutch member is sometimes disengaged from the cage against the urging force of the first urging member when the driver rotates in a state of slight meshing between the clutch member and the cage. In such cases, the shift key sometimes disengages from the clutch member without following it because of the weak urging force of the second urging member. Disengagement of the shift key from the clutch member creates the risk that the shift key will be tilted and rendered incapable of pushing the clutch member any longer.
.[0012] ■
The urging force of the second urging member can be increased in order to prevent this phenomenon. Increasing the urging force of the second urging member makes it necessary, however, for the first urging member to have a fairly strong urging force. When the urging force of the first urging member is increased, the shift control must be moved against the urging force thereof, thus increasing the force needed to perform the above-described shifting operations and impairing shifting.
4 0013] ,
An object of the present invention is to ensure that shifting can be performed with reduced force and that the shift key is rendered less prone to disengagement from the clutch member in a three-speed internal shifter hub.

[ Means Used to Solve the Above-Mentioned Problems ]
The internal bicycle shifter hub pertaining to invention 1 can be mounted on a bicycle frame and is configured such that motive power from an input unit is changed in speed by upshifting, direct linkage, or downshifting, and is transmitted to an output unit by the operation of a shift control. The hub comprises a hub axle, a driver, a slave, a power-transmitting mechanism, and a switching mechanism. The hub axle is one in which the central portion is provided with a guide hole extending in the axial direction from one end to the center, in which the end portion of the guide hole is provided with an axially extending slot that goes all the way through in the radial direction, and which can be fixed on the frame, The driver is rotatably supported on the hub axle and can be linked to the input unit. The slave is a cylindrical element that has a storage space inside, is rotatably supported on the hub axle, and is linkable to the output unit. The power-transmitting mechanism is a mechanism that is disposed in the storage space of the slave, is provided with three power transmission paths (upshift path, direct-link path, and downshift path), and is designed to transmit the motive power from the driver to the slave along any of the power transmission paths. The switching mechanism is a mechanism comprising a cylindrical clutch member that is provided to the hub axle in a rotatable and axially movable fashion and that is designed to select any of the three power transmission paths, a shift rod that is disposed in the guide hole of the hub axle in an axially movable fashion and that is positioned at three axial positions (first position, second position, and third position) by the operation of the shift control, a shift key that is mounted in the slot in an axially movable fashion while allowed to come into contact with the tip of the shift rod and that is used to move the clutch member, an urging member for urging the clutch member toward the shift key, and a link member for linking the shift key to the clutch member in a rotatable and substantially axially immovable fashion; the switching mechanism being designed to switch the power transmission path in the power-transmitting mechanism by the axial movement of the clutch member.
[ QQ15_]
In the internal bicycle shifter hub, the power transmission path is made, for example, into an upshift path by the clutch member when the nonrotatable shift rod housed in the guide hole inside the hub axle is positioned at the first position. Pushed by the shift rod, the shift key moves inside the slot, urging the clutch member in the axial direction, and the clutch member switches the power transmission path, for example, to

the direct-link position, when the shift control is actuated and the shift rod is moved to one side in the axial direction inside the guide hole, reaching the second position. Furthermore, the clutch member switches the power transmission path, for example, to the downshift path when the shift rod is moved to the third position and the clutch member is moved further in the axial direction. The clutch member, urged by the urging member, switches the power transmission path to the direct-link position when the shift rod is moved in this state by the shift control to the other side in the axial direction and is returned to the second position. Urged by the urging member, the clutch member switches the power transmission path to the upshift position when the shift rod is returned to the first position. Here, the shift key can move together with the clutch member because the shift key is linked by a link member to the clutch member in an axially immovable fashion when for some reason the clutch member displays a tendency to move to one side in the axial direction. Consequently, the shift key is unlikely to separate from the clutch member. In addition, dispensing with the need to provide a member for urging the shift key toward the clutch member makes it possible to reduce the urging force of the urging member, and thus to reduce the force needed to operate the shift control for pressing the shift rod against the urging force of the urging member and to shift gears with light force.
The internal bicycle shifter hub pertaining to invention 2 is such that the power-transmitting mechanism in the hub set forth in invention 1 comprises a planetary gear y mechanism comprising a sun gear disposed concentrically with the hub axle and formed integrally with the hub axle, a cage fitted over the hub axle and rotatably supported by the hub axle, planetary gears rotatably mounted in the cage and caused to mesh with the sun gear, and a gear ring that meshes with the planetary gears; a first one-way clutch for linking the driver and the gear ring; a second one-way clutch designed to link the gear ring with the slave and alternated between a linked state and a disengaged state by the clutch member; and a third one-way clutch for linking the cage and the slave; with the clutch member moving into an upshift position in which the driver and the cage are linked to each other and the second one-way clutch is brought into a linked state when the shift rod is positioned at the first position, into a direct-link position in which the link between the driver and the case is released and the second one-way clutch is brought into a linked state when the shift rod is positioned at the second position, and into an upshift position in which the link between the driver and the case is released and the second one-

way clutch is brought into a disengaged state when the shift rod is positioned at the third position.
j-QGW-l
In this case, the clutch member links the driver and the case to each other and converts the second one-way clutch to a linked configuration when the shift rod reaches the first position, the clutch member is moved to the upshift position, and the upshift path is selected. As a result, the motive power of the driver is transmitted first from the clutch member to the cage, and then to the slave via the planetary gear, gear ring, and second one-way clutch, driving the slave at a higher speed.
~[0Q18 j—
The clutch member releases the link between the cage and the driver and converts the second one-way clutch to a linked configuration when the shift rod reaches the second position and the clutch member selects the direct-link path. The motive power of the driver is therefore transmitted to the slave via the first one-way clutch, gear ring, and second one-way clutch, and the slave is driven through a direct link.
The link between the driver and the case is released and the second one-way clutch is brought into a disengaged position when the shift rod reaches the third position and the clutch member selects the downshift path. The motive power of the driver is therefore transmitted to the gear ring via the first one-way clutch. At this time, the second one-way clutch has a disengaged configuration, so the motive power transmitted to the gear ring is transmitted to the slave via the planetary gears, cage, and third one-way clutch without being transmitted to the slave, and the slave is driven at a reduced speed.
■ [0019]-
If motive power is transmitted while the linkage between the clutch member and the cage is inadequate when the shift rod is in the first position, the clutch member sometimes moves in the axial direction against the urging force of the urging member, separating from the cage. Even in such cases, however, the shift key is linked by the link member to the clutch member while prevented from moving in the axial direction, so the shift key moves with the clutch member in interlocked fashion and is unlikely to separate from the clutch member.

f0020 J
The internal bicycle shifter hub pertaining to invention 3 is such that the clutch member in the hub set forth in invention 1 or 2 is provided with an interior storage space capable of accommodating the shift key in a rotatable and axially movable fashion; and the link member links the shift key housed in the storage space to the clutch member in a rotatable and substantially axially immovable fashion. In this case, the shift key is unlikely to separate from the clutch member because this shift key is housed in the storage space formed in the clutch member.
The internal bicycle shifter hub pertaining to invention 4 is such that the shift key in the hub set forth in invention 3 is a bar-shaped member whose length is sufficient to allow both ends thereof to extend from the slot and in which the two end surfaces face the inner peripheral surface of the storage space in the clutch member, and the link member is a ring member engagedly disposed between the clutch member and the shift key. In this case, the clutch member and the shift key can remain connected even when they rotate relative to each other because the clutch member and the shift key are liked together by the ring member.
,[ 002? ]
The internal bicycle shifter hub pertaining to invention 5 is such that, in the hub set forth in invention 4, an annular groove is formed in the inner peripheral surface of the storage space, a long groove capable of facing the annular groove is formed in the two end surfaces facing the inner peripheral surface of the shift key, and the link member is a ring-shaped spring member that has ends and can be secured in the annular groove and long groove. In this case, the link member is a ring-shaped elastic spring member that has ends, so when the shift key is mounted in the storage space of the clutch member, such mounting allows the link member to expand in the radial direction even when this member is mounted in the annular groove in advance. When the shift key is mounted in a mounting position that faces both grooves, the link member is compressed until the two members are locked in place in the two grooves. Mounting of the shift key is therefore facilitated.

The internal bicycle shifter hub pertaining to invention 6 is such that, in the hub set forth in invention 5, the inside diameter of the annular groove is greater than the outside diameter of the link member in a free state. In this case, the link member can easily expand in the annular groove when the shift key is mounted in the clutch member.
The internal bicycle shifter hub pertaining to invention 7 is such that, in the hub set forth in invention 5 or 6, the axial length of the long groove is greater than the thickness of the link member. In this case, the axial length of the long groove is greater than the thickness of the link member, a gap is formed between the link member and the long groove, and the clutch member can rotate smoothly when this member rotates in relation to the shift key. The rolling efficiency of the hub is thus unlikely to decrease.
Accordingly the present invention provides a bicycle hub transmission comprising: an axle; a driving member rotatably ported on the axle; a slave rotatably supported on the axle; a power transmitting mechanism disposed between the driving member and the slave for communicating rotational force from the driving member to the slave through a plurality of power transmitting paths; a clutch member rotatably supported and axially movable on the axle for selecting one of the plurality of power transmitting paths of the power transmitting mechanism; a shift key for moving the clutch member axially; a shift rod axially movably supported to the axle for moving the shift key axially; a biasing mechanism for biasing the clutch member toward the shift key; and a link for linking the clutch member to the shift key so that the clutch member is substantially axially immovable relative to the shift key.
With reference to the accompanying drawings in which:
In Fig. 1, the bicycle obtained by adopting an embodiment of the present invention is a recreational bicycle that comprises a frame 1 composed of a double-loop- shaped frame body 2 and a front fork 3, a handle component 4, a driver unit 5, a front wheel 6, a rear wheel 7 provided with a three-speed internal shifter hub 10, a front brake device 8, and a shift control 9 for the convenient operation of the internal shifter hub 10.

Components such as a saddle 11, the handle component 4, the front wheel 6, and the rear wheel 7 are mounted on the frame 1.
The handle component 4 has a handle stem 14 that is fixed to the top of the front fork 3, and a handlebar 15 that is fixed to the handle stem 14. A brake lever 16, a grip 17, and the shift control 9, which constitute the front brake device 8, are mounted on the right end of the handlebar 15. The shift control 9 is mounted on the handlebar 15 inside the brake lever 16, and is linked to the internal shifter hub 10 by a shift control cable 73 comprising an inner cable and an outer casing. The shift control 9 has a common structure comprising a winding lever for taking up and actuating the inner cable, and a release lever for disabling the winding action of the winding lever and paying out the inner cable. A detailed description will therefore be omitted.

tfcflQ2&^
The driver unit 5 has a chainwheel 18 mounted in the lower portion (bottom bracket) of the frame body 2. The motive power of the chainwheel 18 is transmitted to the internal shifter hub 10 by a chain 19 wound around the chainwheel 18.
[ Structure of Internal Shifter Hub ]
The internal shifter hub 10 is a three-speed hub. As shown in Fig. 2, this internal shifter hub 10 comprises a hub axle 21 fixed in the rear forks (not shown) of the bicycle frame 2, a driver 22 fitted over one end of the hub axle 21, a hub shell (a type of slave) 23 that is disposed farther outward around the outside of the hub axle 21 and the driver 22, a power-transmitting mechanism 25 containing a planetary gear mechanism 24, a switching mechanism 26 for selecting the power transmission path, and a bell crank 27 for actuating the switching mechanism 26.
*PJUJX / J
The hub axle 21 is a bar-shaped member with a large-diameter central portion, two small-diameter end portions, and threads at both ends. A guide hole 21a extending from the left end to the central portion in Fig. 2 is provided in the central core portion of the hub axle 21. A slot 21b going all the way through the central core of the hub axle 21 is provided along the central core at a prescribed distance.
One side of the driver 22 is rotatably supported on the hub axle 21 by balls 30 and a hub cone 31, and a hub cog 32 is fitted over one end. In addition, a plurality of inner serration teeth 22a are formed in the axial direction in the inner peripheral portion of the driver 22 at the other end.
The hub shell 23 is a cylindrical member, and the housing space 23 a along the inner peripheral portion thereof accommodates the driver 22 and the power-transmitting mechanism 25. The hub shell 23 can rotate about the hub axle 21 through the agency of a hub cone 35 and balls 33 and 34. Hub flanges 36 and 37 for supporting spokes 7a (see Fig. 1) are fixed to both ends of the outer peripheral portion of the hub shell 23.
[ Structure of Power-Transmitting Mechanism ]

The power-transmitting mechanism 25 comprises three one-way clutches 50-52 in addition to the planetary gear mechanism 24, and has the three power transmission paths (upshift, direct, and downshift) described below.
The planetary gear mechanism 24 comprises a sun gear 40 formed concentrically to and integrally with the hub axle 21, a gear cage 41 fitted over the hub axle 21, four planetary gears 42 (only two planetary gears are shown in the drawing) meshed with the sun gear 40, and a gear ring 43.
r nmn i
The gear cage 41 is a cylindrical member rotatably supported by the hub axle 21. The gear cage 41 is provided with four notches 41a in the circumferential direction, and a planetary gear 42 is rotatably supported by a pin 44 in each of the notches 41a. Inner serration teeth 41b are formed in the inner peripheral portion at one end of the gear cage 41.
The gear ring 43 is a cylindrical member extending from the planetary gears 42 to the outer periphery of the driver 22. An inner-tooth gear 43b is formed in the inner peripheral portion at the other end of the gear ring 43. The planetary gears 42 mesh with the planetary gear 40 and at the same time with the inner-tooth gear 43b of the gear ring 43 in the manner described above.
A first one-way clutch 50 is mounted between the driver 22 and the gear ring 43. The first one-way clutch 50 is a pawl-type, one-way clutch for transmitting only the rotational motive power of the driver 22 to the gear ring 43 in the direction of travel.
In addition, notches 43a are formed at two facing locations at one end of the gear ring 43, and a clutch pawl 53 constituting a second one-way clutch 51 is pivotably supported by a pin 54 in the notches 43a. The clutch pawl 53 is urged in the upright direction (toward the linked state) by a helical torsion spring 55 wound around the outside of the pin 54. When the second one-way clutch 51 is in the linked state, only the motive power of rotation in the direction of travel is transmitted from the gear ring 43 to the hub shell 23. It is only when the gear ring 43 rotates in the direction of travel that the clutch pawl 53 meshes with the ratchet teeth 23b formed on the inner peripheral surface of the hub shell 23. The second one-way clutch 51 can alternate between a disengaged

state (in which the clutch pawl 53 is retracted from the ratchet teeth 23b) and a linked state (in which the clutch pawl 53 is caused to mesh with the ratchet teeth 23b by the movement of the below-described clutch member) even when the gear ring 43 is in a state in which rotation can be transmitted in the direction of travel.
[.firm ]
A third one-way clutch 52 for transmitting only the motive power of rotation in the direction of travel from the gear cage 41 to the hub shell 23 is disposed between the gear cage 41 and the hub shell 23.
Such a power-transmitting mechanism 25, which comprises a planetary gear mechanism 24 and one-way clutches 50-52, also has the following:
an upshift path composed of a driver 22, a clutch member 45 (described below), a gear cage 41, a planetary gear mechanism 24, a gear ring 43, a second one-way clutch 51, and a hub shell 23;
a direct-link path composed of a driver 22, a first one-way clutch 50, a gear ring 43, a second one-way clutch 51, and a hub shell 23; and
a downshift path composed of a driver 22, a first one-way clutch 50, a gear ring 43, a planetary gear mechanism 24, a gear cage 41, a third one-way clutch 52, and a hub shell 23.
40033-}
[ Structure of Switching Mechanism ]
The switching mechanism 26, which is designed to select one of the three power transmission paths, comprises a clutch member 45 and a clutch actuator 46.
The clutch member 45 switches the driver 22 and the gear cage 41 between a linked state and a disengaged state, and switches the second one-way clutch 51 between a linked state and a disengaged state. The clutch member 45 is fitted over the hub axle 21 while allowed to move and rotate in the axial direction. The clutch member 45 is a cylindrical member (as shown in Fig. 4); outer serration teeth 45a are formed in the outer peripheral portion at one end of the member; and these outer serration teeth 45a are slidably engaged with the inner serration teeth 22a of the driver 22. In addition, a large-diameter portion 45b is formed on the other end of the clutch member 45, and outer

serration teeth 45c are formed in the outer peripheral portion of the member. The outer serration teeth 45c can engage the inner serration teeth 41b formed in the gear cage 41. A tapered surface 45d is formed between the large-diameter portion 45b and one end. This tapered surface 45d is designed to tip the clutch pawl 53 of the second one-way clutch 51 from a linked state (shown by the solid line) into a disengaged state (shown by the broken line in the form of alternate long and two short dashes). When the clutch member 45 moves from the left side toward the downshift position at the right end, the clutch pawl 53 slides along the tapered surface 45d, rises on the large-diameter portion 45b, and assumes the disengaged state. The clutch member 45 is urged toward the gear cage 41 by a coil spring 60.
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A storage space 62 is formed along the inner periphery of the clutch member 45, and an annular groove 63 is formed in the inner peripheral surface thereof, as shown in Fig. 3.
The clutch actuator 46 is designed to move the clutch member 45 in the axial direction of the hub axle 21. The clutch actuator 46 comprises a pushrod 48 that moves in the axial direction inside the guide hole 21a, and a shift key 49 pushed by the pushrod 48 toward the clutch member 45, as shown in Fig. 1.'
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The pushrod 48 is a bar-shaped member whose length is greater than the distance between the left end of the hub axle 21 and the right end of the slot 21b.
The shift key 49 is a member shaped as a square bar moving in the axial direction inside the slot 21b when pushed, as shown in Fig. 3. The shift key 49 is rotatably disposed in the storage space 62 of the clutch member 45 while prevented from moving in the axial direction. The two ends of the shift key 49 extend in the radial direction from the hub axle 21 and are capable of coming into contact with the stepped portions 45e of the clutch member 45. A long groove 49b capable of facing the annular groove 63 is formed in the two end faces 49a of the shift key 49 facing the inner peripheral surface 62a of the storage space 62 of the clutch member 45.

The long groove 49b and the annular groove 63 accommodate a linkage ring 64, which is confined between the two grooves. The linkage ring 64 is designed to link the shift key 49 with the clutch member 45 in a rotatable and axially immovable fashion. The linkage ring 64 is shaped by bending an elastic wire rod into a circular shape, the two end portions of which are slightly separated from each other. In a free state, the outside diameter of the linkage ring 64 is slightly less than the inside diameter of the annular groove 63. The linkage ring 64 can therefore expand in the radial direction when mounted in the annular groove 63. In addition, the length (width) of the long groove 49b in the direction of the hub axle is greater than the wire diameter of the linkage ring 64. The reason is to allow the clutch member 45 to rotate smoothly when this clutch member rotates in relation to the shift key 49.
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[ Structure of Bell Crank ]
The bell crank 27 is mounted on the left end of the hub axle 21. The bell crank 27 comprises a support bracket 70 mounted on the axle end, and a link member 71 pivotably supported by the support bracket 70. The outer casing 73a of the shift control cable 73 is attached to the support bracket 70, and the inner cable 73b is attached to the link member 71. The tip of the link member 71 is pressed against the base end of the pushrod 48. With this arrangement, the link member 71 is pivoted by pulling the inner cable 73b with the aid of the shift control 9, whereupon the pushrod 48 is pushed, the clutch member 45 is pushed by the shift key 49, and a lower speed is selected. On the other hand, loosening the inner cable causes the coil spring 60 to push the clutch member 45, and a higher speed to be selected.
[ Shifting Operations ]
A shifting operation is performed by actuating the pushrod 48 with the bell crank 27 through the agency of the shift control cable 73..
[ Shifting From Higher Speed to Lower Speed ]
In the state shown in Fig. 2, in which the pushrod 48 has not been pushed in, the clutch member 45 is disposed in the upshift position at the left end, and the motive power

from the driver 22 is upshifted through the upshift path and transmitted to the hub shell 23. In this state, the second one-way clutch 51 is in a linked state, so motive power is transmitted from the driver 22 to the gear cage 41 via the clutch member 45, and the motive power transmitted to the gear cage 41 is further transmitted to the hub shell 2.3 via the planetary gear mechanism 24, gear ring 43, and second one-way clutch 51. In this case, input rotation is upshifted and output at a speed ratio determined by the number of teeth on the sun gear 40, planetary gears 42, and gear ring 43. When an attempt is made in this case to transmit rotation from the driver 22 in the direction of the gear ring 43 via the first one-way clutch 50, no rotation is transmitted from the first one-way clutch 50 because the gear ring 43 rotates faster than the driver 22.
Actuating the winding lever of the shift control 9 pivots the link member 71 of the bell crank 27 and pushes the pushrod 48 one step inward. As a result, the shift key 49 is pushed by the link member 71 through the agency of the pushrod 48 against the spring force of the coil spring 60, and is moved to the right in Fig. 3 while guided along the slot 21b. In the process, the clutch member 45 is also pushed and moved to the right, reaching the direct-link position shown by the broken line (alternate long and two short dashes) in Fig. 4, whereby the motive power of the driver 22 is transmitted to the hub shell 23 along the direct-link path. When the clutch member 45 reaches the direct-link position, the gear cage 41 and the driver 22 are no longer linked by the clutch member 45. In this state as well, only the rotation in the direction of travel can be transmitted to the hub shell 23 from the gear ring 43 because the second one-way clutch 51 is in a linked state. Specifically, the rotation that has been input to the driver 22 is transmitted to the gear ring 43 via the first one-way clutch 50 and then to the hub shell 23 via the second one-way clutch 51, and the rotation of the driver 22 is directly transmitted to the hub shell 23 via the gear ring 43. At this time, the rotation is transmitted from the gear ring 43 to the gear cage 41 via the planetary gear mechanism 24, and the gear cage 41 is rotated at a lower speed, but because the hub shell 23 rotates faster than the gear cage 41, there is no transmission of rotation from the gear cage 41 to the hub shell 23 via the third one-way clutch 52.
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When the winding lever of the shift control 9 is actuated from its direct-link state and the pushrod 48 is pushed in even further, the shift key 49 moves further to the right,

and the clutch member 45 is moved in accordance with this to the downshift position shown by the dashed line in Fig. 4. As a result, the clutch pawl 53 of the second one-way clutch 51 is swung into the disengaged state by the tapered surface 45d, and the link between the gear ring 43 and the hub shell 23 is released. The motive power from the driver 22 is therefore transmitted to the hub shell 23 along the downshift path. Specifically, the motive power that has been input to the driver 22 is transmitted to the gear ring 43 via a first one-way clutch 50. The rotation transmitted to the gear ring 43 is further transmitted to the hub shell 23 via the planetary gear mechanism 24, gear cage 41, and third one-way clutch 52. In this case, the input rotation is downshifted and output at a speed ratio determined by the number of teeth on the sun gear 40, planetary gears 42, and gear ring 43.
[ SlufUngJFrom Lower Speed to Higher Speed ]
If the release lever is actuated by the shift control 9 in a downshift state, the link member 71 of the bell crank 27 is retracted, the shift key 49 is pushed by the clutch member 45 (which is, in turn, pushed by the coil spring 60), and the pushrod 48 is pushed as well. The clutch member 45 is brought to a direct-link position. When this happens, the clutch member 45 is separated from the clutch pawl 53 of the second one-way clutch 51, and the clutch pawl 53 is returned to a linked state by the urging force of the helical torsion spring 55. As a result, the motive power of the driver 22 is directly transmitted to the hub shell 23 along the direct-link path described above.
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Further operation of the release lever causes the link member 71 of the bell crank 27 to retract even further, the shift key 49 is further pushed by the clutch member 45 (which is, in turn, pushed by the coil spring 60), and the pushrod 48 is pushed as well. The clutch member 45 is moved to the upshift position, meshing is achieved between the outer serration teeth 45c of the clutch member 45 and the inner serration teeth 41b of the gear cage 41, and the driver 22 and the gear cage 41 are linked to each other. The clutch member 45 sometimes disengages from the gear cage 41 when meshing is inadequate during linkage. Even in such cases, the shift key 49 is linked to the clutch member 45 by the linkage ring 64, making it unlikely that the shift key 49 will separate from the clutch member 45.

[ Other Embodiments ]
(a) Although the above embodiment was described with reference to a link
member shaped as an elastic linkage ring 64 that had ends, the shape of the link member
is not limited to the above-described embodiment and can have any configuration in
which the shift key 49 is linked to the clutch member 45 in a rotatable and axiaily
immovable fashion. As shown, for example, in Fig. 5, it is possible to press-fit a ring-
shaped link member 74 into the end portion of the inner peripheral surface of the clutch
member 45 and to link the shift key 49 in an axiaily immovable fashion. There is no need
in this case to provide the clutch member 45 with an annular groove. Alternately, a
groove may be formed in the end portion of the inner peripheral surface of the clutch
member 45, and a ring-shaped link member 84 composed of an O-ring or a spring may be
mounted therein, as shown in Fig. 6. It is also possible to form the link member as a
C-type retaining ring, an E-type retaining ring, or another type of snap ring.
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(b) Although the above-described embodiment pertained to a case in which a shift key 49 was housed in a clutch member 45, there is no need for the shift key to be housed in the clutch member as long as this key can be pressed against the clutch member.
(c) Although the aforementioned embodiment was described with reference to an internal shifter hub in which a pushrod 48 was inserted through the left end of the hub axle 21, the present invention is also applicable to an internal shifter hub in which the pushrod 48 is inserted through the right end.
[ Merits of the Invention ]
According to the present invention, the shift key can move together with the clutch member because the shift key is linked by a link member to the clutch member in an axiaily immovable fashion when for some reason the clutch member displays a tendency to move to one side in the axial direction. Consequently, the shift key is unlikely to separate from the clutch member. In addition, dispensing with the need to provide a member for urging the shift key toward the clutch member makes it possible to reduce the urging force of the urging member, and thus to reduce the force needed to

operate the shift control for pressing, the shift rod against the urging force of the urging member and to shift gears with light force.
[ Brief Description of the Drawings ]
[ Figure 1 ] A side view of a bicycle obtained by adopting an embodiment of the present invention.
[ Figure 2 ] A cross section of an internal shifter hub.
[ Figure 3 ] An enlarged fragmentary cross section thereof.
[ Figure 4 ] An enlarged fragmentary perspective view thereof.
[ Figure 5 ] A cross-sectional diagram depicting the structure of a clutch member pertaining to another embodiment.
[ Figure 6 ] A cross-sectional diagram depicting the structure of a clutch member pertaining to another embodiment.
[ Key to Symbols ]
2: frame, 9: shift control, 10: internal shifter hub, 21: hub axle, 21a: guide hole, 21b: slot, 22: driver, 23: slave, 24: planetary gear mechanism, 25: power-transmitting mechanism, 26: switching mechanism, 40: sun gear, 41: gear cage, 42: planetary gear, 43: gear ring, 45: clutch member, 48: pushrod, 49: shift key, 49b: long groove, 50: first one-way clutch, 51: second one-way clutch, 52: third one-way clutch, 63: annular groove, 64: linkage ring

WE CLAIM:
1. A bicycle hub transmission comprising: an axle; a driving member rotatably ported on the axle; a slave rotatably supported on the axle; a power transmitting mechanism disposed between the driving member and the slave for communicating rotational force from the driving member to the slave through a plurality of power transmitting paths; a clutch member rotatably supported and axially movable on the axle for selecting one of the plurality of power transmitting paths of the power transmitting mechanism; a shift key for moving the clutch member axially; a shift rod axially movably supported to the axle for moving the shift key axially; a biasing mechanism for biasing the clutch member toward the shift key; and a link for linking the clutch member to the shift key so that the clutch member is substantially axially immovable relative to the shift key.
2. The bicycle hub transmission as claimed in claim 1 wherein the axle has an axially extending guide hole, and wherein the shift rod is disposed in the guide hole.
3. The bicycle hub transmission as claimed in claim 2 wherein the guide hole is centrally disposed in the axle.
4. The bicycle hub transmission as claimed in claim 2 wherein the axle has a slot extending diametrically through the axle, and wherein the shift key is disposed in the slot and extends radially outwardly from the axle.
5. The bicycle hub transmission as claimed in claim 1 wherein the clutch member comprises an interior storage space, and wherein the shift key is disposed within the interior storage space.
6. The bicycle hub transmission as claimed in claim 5 wherein the clutch member has a tubular shape.

7. The bicycle hub transmission as claimed in claim 5 wherein the shift key has an end face that faces an inner peripheral surface of the clutch member.
8. The bicycle hub transmission as claimed in claim 7 wherein the link comprises a ring engaged between the shift key and the clutch member.
9. The bicycle hub transmission as claimed in claim 8 wherein the inner peripheral surface of the clutch member has a clutch member groove, wherein the end face of the shift key has a shift key groove, and wherein the ring is disposed in the clutch member groove and in the shift key groove.
10. The bicycle hub transmission as claimed in claim 9 wherein an axial length of the shift key groove is greater than an axial thickness of the ring.
11. The bicycle hub transmission as claimed in claim 1 wherein the power transmitting mechanism comprises: a sun gear concentrically disposed around the axle; a cage rotatably supported around the axle; a planet gear rotatably supported to the cage and meshing with the sun gear; and a ring gear rotatably supported around the axle and meshing with the planet gear.
12. The bicycle hub transmission as claimed in claim 11 wherein it comprises a first one-way transmission for linking the driving member to the ring gear; a second one-way clutch for linking the ring gear to the slave; and a third one-way clutch for linking the cage to the slave.

13. The bicycle hub transmission as claimed in claim 12 wherein the clutch
member moves to an upshift position for linking the driving member to the cage and
allowing the second one-way clutch to link the ring gear to the slave, wherein the
clutch member moves to a direct-drive position for disengaging the driving member
from the cage and allowing the second one-way clutch to link the ring gear to the
slave, and wherein the clutch member moves to a downshift position for disengaging
the driving member from the cage and disengaging the second one-way clutch to
thereby disengage the ring gear from the slave.
14. The bicycle hub transmission as claimed in claim 11 wherein the axle has a
centrally disposed and axially extending guide hole that communicates with a slot that
extends diametrically through the axle and forms openings on opposite radial sides of
the axle, wherein the shift rod is disposed in the guide hole, and wherein the shift key
is disposed in the slot and extends radially outwardly from the opposite radial sides of
the axle.

Documents:

0647-mas-1999 abstract-duplciate.pdf

0647-mas-1999 abstract.pdf

0647-mas-1999 claims-duplciate.pdf

0647-mas-1999 claims.pdf

0647-mas-1999 correspondence-others.pdf

0647-mas-1999 correspondence-po.pdf

0647-mas-1999 description(complete)-duplciate.pdf

0647-mas-1999 description(complete).pdf

0647-mas-1999 drawings-duplciate.pdf

0647-mas-1999 drawings.pdf

0647-mas-1999 form-1.pdf

0647-mas-1999 form-19.pdf

0647-mas-1999 form-26.pdf

0647-mas-1999 form-3.pdf

0647-mas-1999 form-5.pdf

0647-mas-1999 petition.pdf

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Patent Number

200991

Indian Patent Application Number

647/MAS/1999

PG Journal Number

30/2009

Publication Date

24-Jul-2009

Grant Date

Date of Filing

15-Jun-1999

Name of Patentee

SHIMANO INC.,

Applicant Address

77, OIMATSU-CHO 3-CHO, SAKAI-SHI, OSAKA

Inventors:

#	Inventor's Name	Inventor's Address
1	AKIHIKO SHOGE	1069, YOSHIDA, OAZA, SHIMONISEKI-SHI, YAMAGUCHI

PCT International Classification Number

B62M11/04

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	H10-224326	1998-08-07	Japan