Title of Invention

CLUTCH RELEASE MECHANISM

Abstract

To provide a clutch release mechanism which does not require a large number of components and which can contribute toward a cost reduction. [Solution] A clutch release mechanism is provided which includes a fixed cam member (4 6) supported by a support shaft (45), rotation preventing means (53) provided between the fixed cam member (46) and a crankcase (15) to prevent the fixed cam member (46) from rotating about the support shaft (45), and a movable cam member (47) installed, in a position opposing the fixed cam member (46), to be rotatable coaxially with the support shaft (45). The rotation preventing means (53) includes a rotation preventing shaft section (54) which is formed, integrally with an arm (51a) radially outwardly extending from the fixed cam member (46), by bending a portion of the arm (51a) to be parallel with the support shaft (45), and a rotation preventing hole (55a) which is formed on an inner side of the crankcase (15) and into which the rotation preventing shaft section (54) is fitted. [Selected Drawing] Fig. 4

Full Text

[Document Name] Specification [Title of the Invention] Clutch Release Mechanism [Technical Field] [0001] The present invention relates to improvement of a clutch release mechanism which includes a fixed cam member supported by a support shaft provided in a crankcase of an engine, rotation preventing means provided between the fixed cam member and the crankcase to prevent the fixed cam member from rotating about the support shaft, and a movable cam member installed, in a position opposing the fixed cam member, to be rotatable coaxially with the support shaft, the fixed cam member and the movable cam member being arranged such that the movable cam member is axially reciprocated relative to the fixed cam member as the movable cam member reciprocally rotates, the movable cam member, when axially moving in a direction, causing a clutch to be disengaged. [Background Art] [0002] Such a clutch release mechanism is already known as disclosed in Patent document 1. [Patent Document 1] JP-A No. H01-145427 [Disclosure of the Invention] [Problem to be Solved by the Invention] [0003] Means for preventing a fixed cam member from rotating included in such a clutch release mechanism used to have a rotation preventing pin fixed by riveting or welding to an end portion of an arm radially outwardly extending from the fixed cam member, and a rotation preventing hole which is formed on the inner side of a crankcase and into which the rotation preventing pin is fitted. With the fixed cam member and the rotation preventing pin being discrete parts, respectively, the means required many components, so that there was a limit to cost reduction. [0004] The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a clutch release mechanism which does not require a large number of components and which can contribute toward a cost reduction. [Means for Solving the Problem] [0005] A first characteristic of the present invention intended to achieve the above object is that it provides a clutch release mechanism which includes a fixed cam member supported by a support shaft provided in a crankcase of an engine, rotation preventing means provided between the fixed cam member and the crankcase to prevent the fixed cam member from rotating about the support shaft, and a movable cam member installed, in a position opposing the fixed cam member, to be rotatable coaxially with the support shaft. The fixed cam member and the movable cam member are arranged such that the movable cam member is axially reciprocated relative to the fixed cam member as the movable cam member reciprocally rotates. The movable cam member, when axially moving in a direction, causes a clutch to be disengaged. In the clutch release mechanism, the rotation preventing means includes a rotation preventing shaft section which is formed, integrally with an arm radially outwardly extending from the fixed cam member, by bending a portion of the arm to be parallel with the support shaft, and a rotation preventing hole which is formed on an inner side of the crankcase and into which the rotation preventing shaft section is fitted. [0006] A second characteristic, additional to the first characteristic, of the present invention is that the rotation preventing shaft section includes a pair of piece parts formed by bending side edge portions on both sides of an end portion of the arm such that the pair of piece parts each have a concave side and a circular arc cross-section with the concave sides of the pair of piece parts facing each other. [0007] A third characteristic, additional to the first and second characteristics, of the present invention is that the rotation preventing hole is bounded by an inner circumferential surface of a cylindrical wall protruding on an inner surface of the crankcase and that the cylindrical wall is provided with a cutout to accommodate a portion of the arm. [Effect of the Invention] [0008] According to the first characteristic of the present invention, the rotation preventing shaft section is formed by a portion of and at an end portion of the arm to be integral with the arm. The rotation preventing shaft section can therefore be formed at the same time as when the fixed cam member is press-formed. This makes it possible to reduce the number of components of the fixed cam member to eventually achieve a cost reduction. [0009] According to the second characteristic of the present invention, the rotation preventing shaft section includes the pair of piece parts formed by bending side edge portions on both sides of the arm at a right angle toward a side cover such that the pair of piece parts each have a circular arc cross-section with the concave sides of the pair of piece parts facing each other. While making it easy to press-form the pair of piece parts, i.e. the rotation preventing shaft section, this also makes it possible to secure an adequate fitting area between the rotation preventing shaft section and the rotation preventing hole to enhance the durability of the rotation preventing shaft section. [0010] According to the third characteristic of the present invention, the pair of piece parts, i.e. the rotation preventing shaft section can be entirely fitted into the rotation preventing hole without causing interference between the arm and the cylindrical wall, so that a large fitting area can be secured between the rotation preventing shaft section and the rotation preventing hole. [Best Mode for Carrying Out the Invention] [0011] The mode for carrying out the present invention will be described in the following based on the preferred embodiments shown in the attached drawings. [0012] Fig. 1 is a side view of a motorcycle according to a first embodiment of the present invention. Fig. 2 is an enlarged cross-sectional view of a portion around a clutch included in the engine of the motorcycle. Fig. 3 is an enlarged view of a release mechanism portion shown in Fig. 2. Fig. 4 is a cross-sectional view taken along line 4-4 of Fig. 3, Fig. 5 is a cross-sectional view taken along line 5-5 of Fig, 4. Figs. 6 are cross-sectional views taken along line 6-6 of Fig. 3, Fig. 6A showing a state with the clutch engaged and Fig. 6B showing a state with the clutch disengaged. Fig. 7 is a view, corresponding to Fig. 3, of a second embodiment of the present invention. Fig. 8 is a cross-sectional view taken along line 8-8 of Fig. 7. [0013] First, the first embodiment of the present invention will be described with reference to Figs. 1 to 6. [0014] Referring to Fig. 1, a body frame F of a motorcycle M includes a pipy mainframe section 2 inclined rearwardly and downwardly from a head pipe 1, a pivot support frame section 3 extending downwardly from a rear end portion of the mainframe 2, and a pair of left and right seat rail sections 4 connected to both the pivot support frame section 3 and the rear end portion of the mainframe section 2 and extending rearwardly and upwardly. A steering system 6a for a front fork 6 which supports a front wheel 5f is journalled to the head pipe 1. A steering handlebar 7 is connected to an upper end of the steering system 6a. A pivot shaft 9 is fixed to the pivot support frame section 3. A rear fork 8 to which a rear wheel 5r is j ournailed is supported by the pivot shaft 9 to be swingable up and down. A rear cushion 12 is disposed between the rear fork 8 and the seat rail sections 4. [0015] An engine E positioned midway between the front wheel 5f and the rear wheel 5r is fixed to the mainframe section 2 and the pivot support frame section 3. The power of the engine E is transmitted to the rear wheel 5r via a chain transmission device 11. [0016] The body frame F is attached with a body cover 16 for covering the cylinder section of the engine E. A pair of left and right leg shields 17 are connected to a front end of the body frame. [0017] A crankcase 15 of the engine E supports a change spindle 20 for shifting an internal gear transmission. A change pedal 21 is connected to an outer end portion, protruding from the left side of the crankcase 15, of the change spindle 20. [0018] As shown in Fig. 2, the crankcase 15 includes a case body 15a which rotatably supports an engine crankshaft (not shown) and an input shaft 19 and an output shaft (not shown) of the gear transmission, and a side cover 15b which is separably bolted to the right end face of the case body 15a thereby forming a clutch chamber 22 between itself and the case body 15a. The clutch chamber 22 houses a first reduction gear train 23 arranged between the crankshaft and the input shaft 19 and a clutch 24 which controls the power transmission from the first reduction gear train 23 to the input shaft 19. The change spindle 20 is rotatably supported by the case body 15a and the side cover 15b. [0019] A driven gear 23a included in the first reduction gear train 23 is rotatably supported by the input shaft 19 via a needle bearing 25. The clutch 24 is provided with a bottomed cylindrical clutch outer 30 connected to one side of the driven gear 23a via a rubber damper 26, a clutch inner 33 which is disposed in the clutch outer 30 and splined to the input shaft 19 while also being fixed to the input shaft 19 by a nut 41, plural drive friction plates 31 slidably splined to the inner circumference of the clutch outer 30, at least one driven friction plate 32 slidably splined to the outer circumferential wall of the clutch inner 33 while being interleaved with the drive friction plates 31, a pressure receiving plate 34 which is integrally connected to the clutch inner 33 to be disposed adjacently to the outermost one of the drive fiction plates 31 while being axially slidably splined to the clutch inner 33, and a pressure plate 35 disposed adjacently to the innermost one of the drive fiction plates 31. The pressure plate 35 is integrally provided with plural coupling bosses 37 (one is shown in Fig. 2) each of which penetrates a corresponding one of plural through holes 36 (one is shown in Fig. 2) formed in the clutch inner 33. A release plate 38 is fixed to the end faces of the coupling bosses 37 by bolts 39. Clutch springs 40 are compressedly installed between the release plate 38 and the clutch inner 33. The clutch springs 40 exert, via the release plate 38, a spring force for pressing the pressure plate 35 toward the pressure receiving plate 34. [0020] When the release plate 38 is in a free state, the pushing force of the clutch springs 40 causes the pressure plate 35 to push a group of friction plates including the drive friction plates 31 and the driven friction plates 32 against the pressure receiving plate 34. This brings the drive friction plates 31 and the driven friction plates 32 into mutually pressurized contact, causing the clutch outer 30 and the clutch inner 33 to be coupled and, hence, the clutch 24 to be brought into an engaged state where the power from the crankshaft can be transmitted to the input shaft 19 via the first reduction gear train 23. When the release plate 38 is put in a state opposing the pushing force of the clutch springs 40, and the pressure plate 35 is withdrawn from the friction plate group including the drive friction plates 31 and the driven friction plates 32, the drive friction plates 31 and the driven friction plates 32 are released from each other. This releases the clutch outer 30 and the clutch inner 33 from each other, that is, the clutch 24 is put in a disengaged state, so that the power from the first reduction gear train 23 cannot be transmitted to the input shaft 19. [0021] Referring to Fig. 3, a release mechanism 44 is connected to the release plate 38. The release mechanism 4 4 can move the release plate 38 in the direction for disengaging the clutch 24 when the change spindle 20 rotates in a prescribe manner. The release mechanism 4 4 is provided with a support shaft 45 which is rotatably supported by the side cover 15b coaxially with the input shaft 19, a fixed cam member 46 which is supported by the support shaft 45 in the clutch chamber 22, a movable cam member 47 which is disposed, in a position opposing the fixed cam member 46, to be rotatable relative to the fixed cam member 46, and a clutch lever 48 serration-connected to the change spindle 20 so as to rotate the movable cam member 47. [0022] The support shaft 45 has an adjustment screw shaft section 45a screwed to a hub 50, being described later, of the movable cam member 47, and a flange section 45b abutting on the inner surface of the side cover 15b. Normally, the support shaft 45 is fixed to the side cover 15b by having its outer end portion protruding out of the side cover 15b clamped by a lock nut 49. [0023] The fixed cam member 46 includes the hub 50 screwed to, and thereby supported by, the adj ustment screw shaft section 45a, and a fixed cam plate 51 fixed, by caulking or welding, to the outer circumference of the hub 50. The fixed cam plate 51 is integrally provided with an arm 51a radially extending from the outer circumference of the fixed cam plate 51. Rotation preventing means 5 3 for preventing the fixed cam member 46 from rotating about the support shaft 45 is provided between the arm 51a and the side cover 15b. The rotation preventing means 53 includes a rotation preventing shaft section 54 which is formed by an end portion of the arm 51a to be integral with the arm 51a and which protrudes, in parallel with the support shaft 45, toward the side cover 15b, and a bottomed rotation preventing hole 55a which is formed in the inner wall of the side cover 15b and into which the rotation preventing shaft section 54 can be slidably fitted. [0024] As shown in Figs. 3 to 5, the rotation preventing hole 55a is bounded by the inner surface of a cylindrical wall 55 which, being integral with the side cover 15b, protrudes on the inner wall of the side cover 15b. The rotation preventing shaft section 54 is formed by an end portion of the arm 51a to be integral with the arm 51a. The rotation preventing shaft section 54, particularly preferably, includes a pair of piece parts 54a formed by bending side edge portions on both sides of the arm 51a at a right angle toward the side cover 15b such that the pair of piece parts 54a each have a circular arc cross-section with the concave sides of the pair of piece parts 54a facing each other. The piece parts 54a are formed at the same time as when the fixed cam plate 51 is press-formed out of a steel plate. [0025] The movable cam member 47 includes a hub 52h rotatably supported by the outer circumferential surface of the hub 50, and a movable cam plate 52 formed integrally with the hub 52h at its end portion. The movable cam member 47 is connected to the release plate 38 via a release bearing 61 mounted on the outer circumference of the hub 52h. [0026] The fixed cam plate 51 and the movable cam plate 52 have plural concaves 51b and plural concaves 52b, respectively. The concaves 51b are equidistantly arranged in the circumferential direction on the side to face the movable cam plate 52 of the fixed cam plate 51. The concaves 52b are equidistantly arranged in the circumferential direction on the side to face the fixed cam plate 51 of the movable cam plate 52. A ball 56 held by a retainer 57 is disposed between each pair of mutually opposing concaves 51b and 52b. A spring 58 is compressedly installed between the retainer 57 and the fixed cam plate 51 so as to push the balls 56 toward the movable cam plate 52. [0027] The movable cam plate 52 is integrally provided with an arm 52a extending from its circumference in a radial direction. A roller 48a journalled to an end portion of the clutch lever 48 is engaged in a long hole 60 formed in the arm 52a. [0028] A publicly known neutralizing mechanism 42 pushing the change spindle 20 toward a neutral position is provided between the change spindle 20 and the case body 15a. A publicly known change mechanism (not shown) for controlling a gear transmission is connected to the change spindle 20. [0029] Next, the effects of the first embodiment will be described. [0030] When the change spindle 20 is held in a neutral position, the movable cam member 47, as shown in Fig. 6A, keeps each of its concaves 52b squarely opposing the corresponding one of the concaves 51b of the fixed cam member 46. In this state, each of the balls 56 is deeply positioned between a corresponding pair of mutually opposing concaves 51b and 52b. This allows the movable cam member 47 to be positioned close to the fixed cam member 4 6 causing the release plate 38 to be released. As a result, the pushing force of the clutch springs 40 causes the pressure plate 35 to push the friction plate group including the drive friction plates 31 and the driven friction plates 32 toward the pressure receiving plate 34. This puts the clutch 24 in an engaged state. [0031] When, in the above state, the lock nut 49 is loosened and the support shaft 45 is rotated, the adj ustment screw shaft section 4 5a axially moves the movable cam member 4 7 forward or backward depending on the direction of rotation of the support shaft 45. This makes it possible to appropriately adjust the gaps between the concaves 51b and 52b on the fixed and movable cam members 46 and 47 and the balls 56. When this adjustment is made, the rotation preventing shaft section 54 of the fixed cam member 4 6 slides in the rotation preventing hole 5 5a provided on the side cover 15b thereby allowing the fixed cam member 46 to move axially. [0032] When the change pedal 21 is rotated one stroke from the neutral position so as to shift the gear transmission by one speed stage, the clutch lever 48 rotates, in the first half portion of rotation of the change spindle 20, the movable cam member 47 as shown by an arrow in Fig. 6B causing each of the balls 56 to come out from between a corresponding pair of the concaves 51b and 52b on the fixed and movable cam members 46 and 47. This causes the movable cam member 47 to be pushed in the direction away from the fixed cam member 46, i.e. toward the release plate 38. The push is transmitted to the pressure plate 35 via the release bearing 61 and the release plate 38, so that the pressure plate 35 is withdrawn from the friction plate group including the drive friction plates 31 and the driven friction plates 32 in opposition to the pushing force of the clutch spring 40. As a result, the clutch 24 is put in a disengaged state. [0033] When the change spindle 20 enters the second half portion of rotation, the change mechanism works to shift the gear transmission by one speed stage with the clutch 24 kept in the disengaged state. [0034] Subsequently, when the neutralizing mechanism 42 returns the change spindle 20 to the neutral position, the movable cam member 47 returns to the previous state, so that the repulsive force of the clutch spring 40 returns the release plate 38 and the pressure plate 35 to their previous states, respectively. As a result, the pressure plate 35 again pushes the friction plate group including the drive friction plates 31 and the driven friction plates 32 toward the pressure receiving plate 34. This puts the clutch 24 in an engaged state. [0035] During the time the above process is performed, the rotation preventing shaft section 54 of the fixed cam member 46 being fitted into the rotation preventing hole 55a on the side cover 15b prevents the fixed cam member 4 6 from rotating about the support shaft 45 of the movable cam member 47. Therefore, the movable cam member 47 is allowed to rotate relative to the fixed cam member 46 without fail, so that the release mechanism 4 4 can reliably engage and disengage the clutch 24. [0036] As described in the foregoing, the rotation preventing shaft section 54 is formed by a portion of and at an end portion of the arm 51a to be integral with the arm 51a. The rotation preventing shaft section 54 can therefore be formed at the same time as when the fixed cam plate 51 is press-formed. This makes it possible to reduce the number of components of the fixed cam member 4 6 to eventually achieve a cost reduction. [0037] The rotation preventing shaft section 54, particularly preferably, includes the pair of piece parts 54a formed by bending side edge portions on both sides of the arm 51a at a right angle toward the side cover 15b such that the pair of piece parts 54a each have a circular arc cross-section with the concave sides of the pair of piece parts 54a facing each other. While making it easy to press- form the pair of piece parts 54a, i.e. the rotation preventing shaft section, this also makes it possible to secure an adequate fitting area between the rotation preventing shaft section 54 and the rotation preventing hole 55a to enhance the durability of the rotation preventing shaft section 54. [0038] Next, a second embodiment of the present invention will be described with reference to Figs. 7 and 8. [0039] According to the second embodiment, a cutout 62 opening one side of the rotation preventing hole 55a is formed in a portion of a cylindrical wall 55 formed on the inner wall of the side cover 15b. The cutout 62 accommodates a portion of the arm 51a of the fixed cam member 51. In other respects, the configuration of the present embodiment is the same as that of the first embodiment. Therefore, in Figs. 7 and 8, the same parts as those used in the first embodiment are denoted by the same reference numerals as for the first embodiment, and description of such parts is omitted in the following. [0040] According to the second embodiment, the pair of piece parts 54a, i.e. the rotation preventing shaft section 54 can be entirely fitted into the rotation preventing hole 55a without causing interference between the arm 51a of the fixed cam plate 51 and the cylindrical wall 55, so that a large fitting area can be secured between the rotation preventing shaft section 54 and the rotation preventing hole 55a. [0041] The embodiments of the present invention have been described above, but the present invention is not limited to the embodiments. Various changes can be made to the embodiments without departing from the scope of the invention. [Brief Description of the Drawings] [0042] [Fig. 1] is a side view of a motorcycle according to a first embodiment of the present invention. [Fig. 2] is an enlarged cross-sectional view of a portion around a clutch included in the engine of the motorcycle. [Fig. 3] is an enlarged view of a release mechanism portion shown in Fig. 2. [Fig. 4] is a cross-sectional view taken along line 4-4 of Fig. 3. [Fig. 5] is a cross-sectional view taken along line 5-5 of Fig. 4. [Figs. 6] Fig. 6A is a cross-sectional view taken along line 6-6 of Fig. 3 with the clutch in an engaged state, and Fig. 6B is a cross-sectional view taken along line 6-6 of Fig. 3 with the clutch in a disengaged state. [Fig. 7] is a view, corresponding to Fig. 3, of a second embodiment of the present invention. [Fig. 8] is a cross-sectional view taken along line 8-8 of Fig. 7. [Description of Reference Numerals] [0043] E...Engine 15. . .Crankcase 24...Clutch 4 4 ... Release mechanism 4 5...Support shaft 4 6...Fixed cam member 4 7...Movable cam member 53...Rotation preventing means 54...Rotation preventing shaft section 54a...Piece part 55...Cylindrical wall 55a...Rotation preventing hole 62...Cutout * [Document Name] Scope of Claims [Claim 1] A clutch release mechanism, including: a fixed cam member (4 6) supported by a support shaft (45) provided in a crankcase (15) of an engine (E); rotation preventing means (53) provided between the fixed cam member (46) and the crankcase (15) to prevent the fixed cam member (46) from rotating about the support shaft (45); and a movable cam member (47) installed, in a position opposing the fixed cam member (46), to be rotatable coaxially with the support shaft (45), the fixed cam member (46) and the movable cam member (47) being arranged such that the movable cam member (47) is axially reciprocated relative to the fixed cam member (4 6) as the movable cam member (47) reciprocally rotates, the movable cam member (47), when axially moving in a direction, causing a clutch (24) to be disengaged, wherein the rotation preventing means (53) comprises: a rotation preventing shaft section (54) which is formed, integrally with an arm (51a) radially outwardly extending from the fixed cam member (46), by bending a portion of the arm (51a) to be parallel with the support shaft (45); and a rotation preventing hole (55a) which is formed on an inner side of the crankcase (15) and into which the rotation preventing shaft section (54) is fitted. [Claim 2] The clutch release mechanism according to Claim 1, wherein the rotation preventing shaft section (54) comprises a pair of piece parts (54a) formed by bending side edge portions on both sides of an end portion of the arm 51a such that the pair of piece parts (54a) each have a concave side and a circular arc cross-section, the concave sides of the pair of piece parts (54a) facing each other. [Claim 3] The clutch release mechanism according to one of Claims 1 and 2; wherein the rotation preventing hole (55a) is bounded by an inner circumferential surface of a cylindrical wall (55) protruding on an inner surface of the crankcase (15), and the cylindrical wall (55) is provided with a cutout (62) to accommodate a portion of the arm (51a) .

Documents:

0380-che-2007-abstract.pdf

0380-che-2007-claims.pdf

0380-che-2007-correspondnece-others.pdf

0380-che-2007-description(complete).pdf

0380-che-2007-drawings.pdf

0380-che-2007-form 1.pdf

0380-che-2007-form 26.pdf

0380-che-2007-form 3.pdf

0380-che-2007-form 5.pdf

0380-che-2007-form18.pdf

380-CHE-2007 OTHER PATENT DOCUMENT 17-08-2009.pdf