Title of Invention

"GEAR ASSEMBLING STRUCTURE"

Abstract

To enhance workability in assembling a gear to a shaft by providing a stabilized hold for a key member using a collar member fitted in the shaft, thereby preventing the key member from coming off position. [Solving Means] The invention is applied to assembling of a balancer shaft 2, to which a rotary driving force of a crankshaft 1 is transmitted through meshing between a balancer drive gear 1h on the crankshaft 1 and a balancer driven gear 3 on the balancer shaft 2. The balancer driven gear 3 is assembled to the balancer shaft 2 using a key member and a keyway. Specifically, part of a key member 4. is inserted and held between a keyway 51 in a collar member 5 and a keyway 23 in the balancer shaft 2. The assembling of the balancer driven gear 3 to the balancer shaft 2 is achieved by a keyway 3g in the balancer driven gear 3 being fitted over the key member 4 which is in a condition of being inserted and held in position by the keyway 51 of the collar member 5 and the keyway 23 of the balancer shaft 2.

Full Text

The present invention relates to gear assembling structure. The present invention relates to an assembling structure for a gear in a shaft and, more particular, to an assembling structure for a balancer driven gear in a balancer shaft of an internal combustion engine. [Background Art] In a conventional internal combustion engine provided with a balancer, a key member and a keyway are often used for assembling a balancer driven gear to a balancer shaft. For such a type of the engine, an assembling method is employed, in which a keyway in the balancer driven gear is fitted over a key member previously press-fitted into, and held in, a keyway in the balancer shaft. This is done for purposes of phase alignment between the balancer shaft and a crankshaft. This gear assembling method has, however, the following drawback. Specifically, the assembling method involves the key member being press-fitted and held in the keyway in the shaft. This makes it necessary to use a hammer or the like when driving the key member into the keyway. It is difficult to perform this job of hammering the key member into the keyway in the case of the shaft, in which the key member has previously been press-fitted into the keyway therein. This results in an extremely poor workability. The following gear assembling method, instead of the gear assembling method mentioned above, is very often employed when assembling the gear onto the previously assembled shaft. Specifically, the key member is held loosely, not in a press-fit condition, in the keyway in the shaft. The keyway in the gear is then fitted over the key member (see, for example, Patent Document 1). [Patent Document 1] Japanese Utility Model Laid-open No. Hei 4-30339 (FIG. 2 on page 2) [Disclosure of the Invention] [Problem to be Solved by the Invention] \[0003] In the invention disclosed in Patent Document 1 shown in FIG. 5, a balancer shaft 02 is assembled to a crankshaft 01 with phase alignment made with each other. When the balancer shaft 02 is assembled, therefore, alignment marks (not shown) made on a balancer drive gear Olh on the crankshaft 01 and on a balancer driven gear 03 assembled to the balancer shaft 02 are used. Assembling of the balancer driven gear 03 onto the balancer shaft 02 is made with respect to the previously assembled balancer shaft 02. A key member 04 has previously been held in a keyway 023 in the balancer shaft 02. The key member 04 is a relatively loose fit in the keyway 023 . The balancer driven gear 03 is fitted to the balancer shaft 02 that holds the key member 04 in position. The balancer driven gear 03 is rotated on the balancer shaft 02 as necessary so that an alignment mark (not shown) thereon is aligned with an alignment mark (not shown) on the balancer drive gear Olh mounted on the crankshaft 01. The balancer driven gear 03 is held in position in this condition. When the balancer shaft 02 is rotated as necessary and the key member 04 thereof and a keyway 03g in the balancer driven gear 03 are aligned with each other, the balancer driven gear 03 is pushed in to make an insertion coupling between the key member 04 and the keyway 03g in the balancer driven gear 03 . At the same time, the balancer driven gear 03 is brought into mesh with the balancer drive gear Olh on the crankshaft 01. The balancer driven gear 03 is now assembled to the balancer shaft 02 . Assembling of the balancer driven gear to the balancer shaft in accordance with the invention disclosed in Patent Document 1 is made with the key member being a loose fit in the keyway in the balancer shaft. This provides a benefit of an easy job of inserting the key member into the keyway. When assembling the balancer driven gear 03, however, the key member 04 is easy to come off the keyway 023 in the balancer shaft 02. This makes it necessary to assemble the balancer driven gear 03, while holding the key member 04 in position with a hand. There remains a problem, therefore, that the job is hard to perform and workability of the job is poor. [43.006] — In the conventional well-known gear assembling structure described above, in which the key member is previously press-fitted and held in the keyway, the key member is press- fitted into the keyway in the previously assembled balancer shaft. This makes it necessary to use a hammer when driving the key member into the keyway. Such a hammering job in a narrow space is a hard task to perform. There remains a problem of poor workability. There is therefore a need for an assembling structure for a gear in a shaft using a key member and a keyway that offers the following benefits. Specifically, a measure is taken in the structure to prevent the key member from coming off position; the structure offers outstanding workability of gear assembling; the structure contributes to a reduced assembly cost; and the structure is extremely simple. In particular, a need exists for an assembling structure as applied to assembling a balancer driven gear to a balancer shaft using a key member and a keyway. Such an assembling structure is capable of achieving the following objects: specifically, improved workability of gear assembling job; reduced cost; and simplified structure. [Means for Solving the Problem] |, Q n n a ] The present invention relates to an improved structure of an assembling structure for a gear for solving the aforementioned problems. The present invention applies to an assembling structure for a gear that uses a key member and a keyway for assembling the gear to a shaft. The gear assembling structure includes the shaft and the following specific components. The components specifically include: a collar member fitted to the shaft and having a keyway, into which a key member is inserted; a key member, part of which is inserted and held between the keyway in the collar member and the keyway in the shaft in a fit condition of the collar member in the shaft; and a gear, a keyway in which is fitted over the key member, part of which is inserted and held. The gear assembling structure is characterized in the following point. Specifically, fitting the keyway in the gear over the key member, part of which is inserted and held between the keyway in the collar member and the keyway in the shaft, secures the gear to the shaft through the key member. The gear assembling structure is also characterized in that the gear is a balancer driven gear and the shaft is a balancer shaft of an internal combustion engine. [Effect of the Invention] A gear assembling structure as claimed in claim 1 of the present invention includes the following components, as applied to a gear assembling structure that uses a key member and a keyway for assembling a gear to a shaft. The components of the gear assembling structure include: the shaft; a collar member fitted to the shaft and having a keyway, into which a key member is inserted; a key member, part of which is inserted and held between the keyway in the collar member and the keyway in the shaft in a fit condition of the collar member in the shaft; and a gear, a keyway in which is fitted over the key member, part of which is inserted and held. The gear assembling structure is characterized in that fitting the keyway in the gear over the key member, part of which is inserted and held between the keyway in the collar member and the keyway in the shaft, secures the gear to the shaft through the key member. This arrangement produces the following condition. Specifically, during work performed for assembling the gear and prior to a step of assembling the gear, part of the key member is in a condition of being inserted and held between the keyway in the collar member and the keyway in the shaft. This prevents the key member from coming off the shaft. In addition, there is no need of holding the key member with a hand during insertion of the gear onto the key member. This facilitates the work of assembling the gear onto the shaft, thus enhancing workability by a large margin and reducing an assembly cost. [0010] The gear assembling structure as claimed in claim 2 of the present invention is characterized in that the gear is a balancer driven gear and the shaft is a balancer shaft of an internal combustion engine. In assembling the balancer driven gear to the balancer shaft, there is no chance that the key member held in position by the balancer shaft will come off position. This eliminates the need for holding the key member with a hand during assembly of the driven gear. This facilitates the assembly job, thus enhancing workability and reducing cost in the assembly job. [Best Mode for Carrying Out the Invention] The present invention is carried out in work of assembling the balancer driven gear to the balancer shaft of an internal combustion engine. [Embodiment] [00121 A preferred embodiment of the present invention will be described with reference to FIGS. 1 through. 4. Accordingly the present invention relates to an assembling structure for a gear that uses a key member and a keyway for assembling the gear to a shaft, comprising: the shaft; a collar member (5) fitted to the shaft (2) and having a keyway (51) into which a key member (4) is inserted; a key member (4), part of which is inserted and held between the keyway (51) in the collar member (5) and a keyway (51) in the shaft (2) in a fit condition of the collar member (5) in the shaft (2); and a gear (3), a keyway (51) in which is fitted over the key member (4), part of which is inserted and held; wherein fitting the keyway (51) in the gear over the key member (4), part of which is inserted and held between the keyway (51) in the collar member (5) and the keyway (51) in the shaft, secures the gear (3) to the shaft (2) through the key member (4) wherein the gear (3) is a balancer driven gear and the shaft (2) is a balancer shaft of an internal combustion engine. [Brief Description of the Drawings] [FIG. 1] FIG. 1 is a side elevational view showing a structure of parts near a crankcase of an internal combustion engine, to which an assembling structure for a gear according to a preferred embodiment of the present invention is applied. [FIG. 2] FIG. 2 is a longitudinal cross sectional view showing a structural portion of a crankcase of an internal combustion engine, to which an assembling structure for a gear according to a preferred embodiment of the present invention is applied. [FIG. 3] FIG. 3 is a view showing a principal portion of an assembling structure for a gear according to a preferred embodiment of the present invention is applied. [FIGS. 4A, 4B, and 4C] FIGS. 4A to 4C are views showing a structure of"a balancer driven gear, FIG. 4A being a sectional view taken along line A-A in FIG. 4C, FIG. 4B being a side elevational view showing one side of FIG. 4A, partly cut away, and FIG. 4C being a side elevational view showing the other side of FIG. 4A, partly cut away. [FIG. 5] FIG. 5 is a longitudinal cross sectional view showing a structural portion of a crankcase of an internal combustion engine, to which a prior art assembling structure for a gear is applied.FIGS. 1 and 2 show structural members of an internal combustion engine, to which an assembly structure for a balancer driven gear 3 according to the preferred embodiment of the present invention is applied. FIG. 1 is a side elevational view showing a crankcase 10of an internal combustion engine E. FIG. 2 is a longitudinal sectional view showing the crankcase 10 of the internal combustion engine E.Referring to FIG. 2, a crankshaft I is rotatably bearing supported in the crankcase 10. The bearing support for the crankshaft 1 is provided at positions on both ends of a crankpin 11 adjacent to the crankpin 11 of the crankshaft 1. As shown in, and referring to, FIG. 2, the bearing support on the right-hand side is provided by a roller bearing la, and the bearing support on the left-hand side is provided by a ball bearing Ib. A large end portion Id of a connecting rod Ic is rotatably supported on the crankpin 11 of the crankshaft 1. As is well known, a piston is mounted through a piston pin in a small end portion of the connecting rod 1c, though not shown.[0014]A sprocket le for cam chain drive is mounted on the crankshaft 1, at a location leftward of a point adjoining the bearing support portion provided by the ball bearing Ib . Further, a starter driven gear If is mounted outward of the sprocket le. A generator Ig is mounted on an end portion of the crankshaft 1 further outward of the starter driven gear If. A pair of large and small gears1h, li are mounted rightward and outward of the bearing support portion provided by the roller bearing la for the crankshaft 1. The two gears Ih, li adjoin a right outer side portion of the bearing support portion. The large gear Ih is a balancer drive gear. The gear Ih meshes with the balancer driven gear 3 mounted on a balancer shaft 2 .Referring to FIG. 1 that shows part of meshing conditions of the small gear li, the gear li is a drive gear that meshes with a driven gear 8a loosely fitted on a main shaft 8 of a transmission. A rotary driving force of the small gear li is transmitted through meshing of the small gear li with the driven gear 8a and by way of a clutch to the main shaft 8 of the transmission. The rotary driving force transmitted to the main shaft 8 is transmitted to a countershaft 9 through selection of a desired gear ratio achieved by a speed change gear drive provided between the main shaft 8 and the countershaft 9 . A driving wheel is thereby driven for running a vehicle as necessary through appropriate driving means not shown.A balancer shaft 2 is rotatably supported by a bearing support portion 2 a and a bearing support portion 2b as shown in FIG. 2. The bearing support portion 2a islocated at a position on a right side relatively near a central portion of the crankcase 10. The bearing support portion 2b is on a shaft end to the left of the bearing support portion 2a. The balancer shaft 2 therefore has a protruded shaft portion 21 that passes through the bearing support portion 2a at the rightward position and extends further outwardly over a predetermined length. Each of the bearing support portions 2a and 2b of the balancer shaft 2 is formed by a ball bearing. The distance between the bearings in the bearing support portions 2a and 2b is set to have substantially the same distance between the bearing support portions for the crankshaft 1. The protruded shaft portion 21 that passes through the bearing support portion 2a rightward of the balancer shaft 2 and extends further outwardly is mounted with the balancer driven gear 3 mentioned earlier. A balancer weight 22 is provided for the balancer shaft 2. The balancer weight 22 is located at a central portion between the bearing support portions 2a and 2b. This position is at a substantially leftward side in terms of an entire length of the balancer shaft 2 . The balancer weight 22 is formed integrally with the balancer shaft 2 through forging, casting, or the like. The balancer weight 22 is positioned on a centerline between counterweights 12, 12 of the crankshaft 1 when the balancer shaft 2 is assembled into position. This positioning of the balancer weight 22 ensures that the balancer weight 22 rotates between, and without touching, the counterweights 12, 12 of the crankshaft 1 when the balancer weight 22 takes a rotating position relative to the counterweights 12, 12 of the crankshaft 1 as shown in FIG. 2. The balancer weight 22 positioned on the centerline between the counterweights 12, 12 of the crankshaft 1 when the balancer shaft 2 is assembled into position is rotated in synchronism with, and in phase opposite to, the counterweights 12, 12 of the crankshaft 1. As shown in FIG. 2, the balancer weight 22 of the balancer shaft 2 is located on an uppermost position when the counterweights 12, 12 of the crankshaft 1 are located on a bottom position. The condition, in which a good part of the balancer weight 22 is accommodated between the counterweights 12, 12, is one readily understandable form in the synchronized rotation with opposite phases. [0020] The balancer shaft 2 having the structure as described in the foregoing functions to absorb and ease vibrations produced as a result of fluctuations in torque for driving an engine received by the crankshaft 1. When the balancer weight 22 rotates in synchronism with, and in phase opposite to, the counterweights 12, 12 of the crankshaft 1 as described above, the balancer weight 22 offsets vibrations based on torque fluctuations in the crankshaft 1. The balancer weight 22 thus inhibits and eases vibrations produced from the torque fluctuations. A balancer shaft such as the balancer shaft 2 described above is well known. In FIGS. 1 and 2, M represents a starter motor. As described earlier, the balancer driven gear 3 is mounted on the protruded shaft portion 21 of the balancer shaft 2. Referring to FIGS. 3 and 4A, 4B, and 4C, the balancer driven gear 3 includes a gear member 31 and a bushing member 32. The gear member 31 is on an outer race side, in which a gear 3a is formed on an outer peripheral portion thereof. The bushing member 32 is on an inner race side provided with a mounting base portion 3b to be described later that serves as a mounting portion to the balancer shaft 2. The balancer driven gear 3 is mounted on the balancer shaft 2 when the bushing member 32 on the inner race side is secured to the balancer shaft 2 using a woodruff key 4 as a key member of a half-moon shape to be described later. [0022] A damper spring 3c and a damper rubber 3d are interposed between the gear member 31 on the outer race side and the bushing member 32 on the inner race side of the balancer driven gear 3. A coned disc spring 3e presses one side face of the gear member 31 on the outer race side toward the bushing member 32 on the inner race side (see FIG. 4A) . When the gear 3a formed on the outer peripheral portion of the gear member 31 on the outer race side meshes with the balancer drive gear Ih, the rotary driving force of the crankshaft 1 is transmitted to the gear member 31 on the outer race side. The rotary driving force transmitted to the gear member 31 on the outer race side lets the gear member 31 on the outer race side rotate. The rotation of the gear member 31 on the outer race side compresses the damper spring 3c, and then the damper rubber 3d. The rotation is thereby transmitted to the bushing member 32 on the inner race side, allowing the bushing member 32 on the inner race side to rotate.As observed, the rotary driving force is transmitted from the gear member 31 on the outer race side to the bushing member 32 on the inner race side in the balancer driven gear 3 by way of the damper spring 3c and the damper rubber 3d. Through this process of drive transmission, pulsating fluctuations in torque of the driving force of the crankshaft 1 is effectively absorbed and eased through an impact absorbing effect and a buffering effect brought about by the damper spring 3c and the damper rubber 3d. This eliminates rattling noise between the balancer drive gear Ih and the balancer driven gear 3 . The rotary driving force is then transmitted to the balancer shaft 2 by way of the mounting base portion 3b to be described later that serves as the mounting portion for the balancer driven gear 3 . As shown in FIG. 3 and as will be described in detail later, the balancer driven gear 3 is mounted to the balancer shaft 2 using the woodruff key 4 as a key member. The bushing member 32 on the inner race side is provided with the mounting base portion 3b formed as a boss and having a shaft hole 3f for fit to the balancer shaft 2 . The mounting base portion 3b is much longer than an axial length (gear width) of the gear member 31 on the outer race side. A keyway 3g of a predetermined width and a predetermined depth is formed in an inner peripheral surface of the shaft hole 3f of the boss mounting base portion 3b. The keyway 3g in the shaft hole 3f extends linearly in a longitudinal direction on the inner peripheral surface of the shaft hole 3f to run across both end portions of the boss mounting base portion 3b. Throughout an entire length thereof, the keyway 3g has the predetermined width and the predetermined depth. A keyway 23 is formed, on the other hand, in the balancer shaft 2 . The keyway 23 corresponds to the keyway 3g formed in the shaft hole 3f of the mounting base portion 3b of the balancer driven gear 3 . The keyway 23 is formed in the protruded shaft portion 21 extending from the bearing support portion 2a at the rightward position of the balancer shaft 2. The keyway 23 is located near a ball bearing 2al of the rightward bearing support portion 2a. The keyway 23 is formed so as to bore circularly arcuately part of a surface of the protruded shaft portion 21 along a longitudinal direction. The keyway 23 is bored to a predetermined width and a predetermined depth. The keyway 23 is thus shaped to receive an arcuate portion of the woodruff key 4 of a half -moon shape. The predetermined width of the keyway 23 is substantially the same as that of the woodruff key 4. Mounting of the balancer driven gear 3 to the balancer shaft 2 will be described in detail with reference to FIG. 3. As described earlier, the balancer driven gear 3 is mounted to the protruded shaft portion 21 protruding from the ball bearing 2al as the rightward bearing support portion 2a of the balancer shaft 2. The balancer driven gear 3 is mounted using the woodruff key 4 by way of the keyway 3g formed in the shaft hole 3f. Securing of the balancer driven gear 3 using the woodruff key 4 is accomplished by inserting the woodruff key 4 simultaneously into both a keyway 51 in an annular collar member 5 and the keyway 3g in the balancer driven gear 3 . [0028] The annular collar member 5 has an inner diameter that is substantially the same as an outside diameter of the balancer shaft 2. The keyway 51 for receiving the woodruff key 4 is formed in the inner diameter of the annular collar member 5. The keyway 51 has substantially the same width and depth as the keyway 3g formed in the balancer driven gear 3. The keyway 51 is formed to run across both ends in an axial direction of the annular collar member 5. In a condition, in which the balancer driven gear 3 is assembled as shown in FIG. 3, a leftward side face 5b of the annular collar member 5 abuts against a side face of the ball bearing 2al of the rightward bearing support portion 2a for the balancer shaft 2. Further, a rightward side face 5a of the annular collar member 5 abuts against the balancer driven gear 3 through a relation of simultaneous insertion of the woodruff key 4. [0029] The balancer driven gear 3 is assembled to the balancer shaft 2 through the following steps. Specifically, the annular collar member 5 having the keyway 51 is fitted to the balancer shaft 2 that is rotatably supported through ball bearings 2al, 2bl in the crankcase 10, as accessed from a rightward end thereof. The leftward side face 5b of the annular collar member 5 is thereby brought into abutment against the right side face of the ball bearing 2al. The annular collar member 5 is then rotated as necessary so that the keyway 23 in the balancer shaft 2 is aligned with the keyway 51 in the annular collar member 5. With the two keyways 23, 51 aligned with each other, the half -moon-shaped woodruff key 4 as the key member is inserted into the keyway 23 . During this step, an arcuate bottom portion of the woodruff key 4 is slid along the keyway 23 having the arcuately bored shape in the balancer shaft 2 . A leading end portion of the woodruff key 4 is thus inserted between the two keyways 23, 51. Insertion of the woodruff key 4 between the keyway 23 in the balancer shaft 2 and the keyway 51 in the collar member 5 is accomplished as follows. Specifically, referring to FIG. 3, part of the woodruff key 4, or more specifically, about 1/3 of an entire length of the woodruff key 4 is inserted into the keyway 51 in the collar member 5. For a remainder portion of about 2/3 of the entire length of the woodruff key 4, the arcuate bottom portion of the woodruff key 4 is inserted only in the keyway 23 in the balancer shaft 2, while a straight front surface side of the woodruff key 4 is an exposed key portion 4a substantially protruding from a front surface of the balancer shaft 2. In this condition, the woodruff key 4 is inserted and held (secured) in the keyway 51 in the collar member 5 and the keyway 23 in the balancer shaft 2. Then, the balancer driven gear 3 is fitted to the balancer shaft 2, in which the woodruff key 4 is held in the condition described above. In this case, the balancer driven gear 3 is mounted on the balancer shaft 2 from a rightward end side thereof. The balancer driven gear 3 fitted to the balancer shaft 2 is not brought into mesh with, but brought near to, the balancer drive gear Ih of the crankshaft 1. The balancer driven gear 3 is then rotated on the balancer shaft 2 a predetermined amount so that a meshing alignment mark made on the balancer driven gear 3 is aligned with a meshing alignment mark (neither of the alignment marks are shown) made on the balancer drive gear Ih of the crankshaft 1. With the meshing alignment mark made on the balancer driven gear 3 aligned with the meshing alignment mark made on the balancer drive gear Ih of the crankshaft 1, the balancer driven gear 3 is held in position by hand. Keeping that condition, the balancer shaft 2 is rotated until the woodruff key 4 retained on the balancer shaft 2 by the collar member 5 is aligned with the keyway 3g in the balancer driven gear 3. The following step is performed when the woodruff key 4 retained on the balancer shaft 2 is aligned with the keyway 3g in the balancer driven gear 3 . Specifically, an end of the keyway 3g in the balancer driven gear 3 is oriented toward an end portion of the exposed key portion 4a described earlier of the woodruff key 4 on the balancer shaft 2 . The balancer driven gear 3 is then pushed on the balancer shaft 2 toward the left in FIG. 3 to allow the key member 4 to be inserted in, and connected to, the keyway 3g in the balancer driven gear 3. At the same time, the balancer driven gear 3 is brought into mesh with the balancer drive gear Ih on the crankshaft 1 and the leftward side portion of the balancer driven gear 3 is brought into abutment against the rightward side face 5a of the collar member 5. A clamp nut 7 is thereafter tightened by way of a washer 6 over a threaded portion 24 on a rightward shaft end of the balancer shaft 2. This applies pressure to the mounting base portion 3b of the bushing member 32 on the inner race side of the balancer driven gear 3. Further, the leftward side face 5b of the annular collar member 5 is brought into abutment against the rightward side face of the ball bearing 2al by way of the balancer driven gear 3 . This results in the balancer driven gear 3 being integrated with the annular collar member 5. The balancer driven gear 3 is thus assembled to the balancer shaft 2 in a condition of being even solidly secured by the woodruff key 4 . The balancer driven gear 3 is secured at a position near the shaft end, or the protruded shaft portion 21 of the balancer shaft 2. [903D]' " As described in the foregoing, prior to the step of assembling the balancer driven gear 3 to the balancer shaft 2 using the woodruff key 4, part of the woodruff key 4 is in a condition of being inserted and held between the keyway 51 in the collar member 5 and the keyway 23 in the balancer shaft 2. This prevents the woodruff key 4 from coming off the balancer shaft 2 . [003G] - When assembling the balancer driven gear 3 to the balancer shaft 2, there is no need of holding the woodruff key 4 with a hand. The assembly of the balancer driven gear 3 to the balancer shaft 2 is therefore extremely easy, thus enhancing workability by a large margin and reducing an assembly cost. [Industrial Applicability] The gear assembling structure according to the present invention can be applied to assembling of a gear in various types of machinery, vehicle, and the like. [Description of Reference Numerals] 1 Crankshaft la Roller bearing 1b Ball bearing 1c Connecting rod 1d Large end portion of a connecting rod 1e Sprocket for cam chain drive 1f Starter driven gear 1g Generator 1h Balancer drive gear li Drive gear 10 Crankcase 11 Crankpin 12 Counterweight 2 Balancer shaft 2a Bearing support portion 2al Ball bearing 2b Bearing support portion 2bl Ball bearing 21 Protruded shaft portion 22 Balancer weight 2 3 Keyway 24 Threaded portion 3 Balancer driven gear 3a Gear 3b Mounting base portion 3c Damper spring 3d Damper rubber 3e Coned disc spring 3f Shaft hole 3g Keyway 31 Gear member 32 Bushing member 4 Woodruff key 4a Exposed key portion 5 Annular collar member 5a Rightward side face 5b Leftward side face 51 Keyway 6 Washer 7 Clamp nut 8 Main shaft 8a Driven gear 9 Countershaft E Internal combustion engine M Starter motor WE CLAIM 1. An assembling structure for a gear that uses a key member and a keyway for assembling the gear to a shaft, comprising: the shaft; a collar member (5) fitted to the shaft (2) and having a keyway (51) into which a key member (4) is inserted; a key member (4), part of which is inserted and held between the keyway (51) in the collar member (5) and a keyway (51) in the shaft (2) in a fit condition of the collar member (5) in the shaft (2); and a gear (3), a keyway (51) in which is fitted over the key member (4), part of which is inserted and held; wherein fitting the keyway (51) in the gear over the key member (4), part of which is inserted and held between the keyway (51) in the collar member (5) and the keyway (51) in the shaft, secures the gear (3) to the shaft (2) through the key member (4) wherein the gear (3) is a balancer driven gear and the shaft (2) is a balancer shaft of an internal combustion engine. 2. An assembling structure for a gear substantially as hereinbefore described with reference to the accompanying drawings.

Documents:

1476-del-2004-abstract.pdf

1476-del-2004-claims.pdf

1476-del-2004-correspondence-others.pdf

1476-del-2004-correspondence-po.pdf

1476-del-2004-description (complete).pdf

1476-del-2004-drawings.pdf

1476-del-2004-form-1.pdf

1476-del-2004-form-19.pdf

1476-del-2004-form-2.pdf

1476-del-2004-form-3.pdf

1476-del-2004-form-5.pdf

1476-del-2004-gpa.pdf

1476-del-2004-petition-137.pdf

1476-del-2004-petition-138.pdf

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