Title of Invention

"CONNECTION STRUCTURE BETWEEN PLASTIC GEAR AND SHAFT'

Abstract

[Name of Document] Abstract [Abstract] [Object] To provide a connection structure between a plastic gear and a shaft, such a connection structure being suitable for a plastic gear and permitting easy phase matching relating to a device mounted on the shaft and easy meshing of a gear provided on the shaft with another. [Solving Means] The connection structure is characterized by the following arrangements. The arrangements specifically include: a mortise is provided at a central portion of a rectangular set plate; a rectangular recessed portion, in which the set plate fits, is provided on a front surface of a portion of the plastic gear, to which the shaft is connected, and the set plate is thereby mounted; a tenon, which is to be passed through the mortise provided in the set plate, is provided on the side of an end of the shaft, at which the gear is connected; the tenon is set to have such a length that, when the plastic gear is to be connected to the shaft, the mortise is first aligned with the tenon and then a step of mounting the tenon in the mortise is proceeded, and when the mounting step of the tenon in the mortise is proceeded a predetermined amount, the plastic gear is meshed with the mating gear. [Selected Drawing] FIG. 3

Full Text

[Name of Document] Specification [Title of the Invention] Connection Structure Between Plastic Gear And Shaft [Technical Field] The present invention relates to a connection structure between a plastic gear and a shaft. [Background Art] [0002] A method is conventionally known for connecting an oil pump shaft to a gear that transmits a driving force thereto. The method, specifically, includes the following steps: providing a U-shaped groove across a center hole in the gear; fitting a lock pin into a through hole provided perpendicularly relative to a centerline of the shaft; and pushing the shaft into the center hole in the gear, thereby fitting the lock pin into the groove in the gear (see, for example, Patent Document 1). Since the lock pin is mounted in the through hole provided perpendicularly relative to the centerline of the shaft, an axial position of the shaft is not free relative to an axial position of the gear. This makes it difficult, due to the lock pin coming off position, to perform phase matching of an oil pump rotor when the gear is not in mesh with a mating gear. [Patent Document 1] Japanese Utility Model Publication No. Hei 3-38470 (FIGS. 1 and 2) [Disclosure of the Invention] [Problem to be Solved by the Invention] An object of the present invention is to provide a connection structure between a plastic gear and a shaft, such a connection structure being suitable for a plastic gear and permitting easy phase matching relating to a device mounted on the shaft and easy meshing of a gear provided on the shaft with another [Means for Solving the Problem] [0006] To achieve the aforementioned object, a connection structure between a plastic gear and a shaft as claimed in claim 1 of the present invention connects a plastic gear that meshes with a drive gear or a driven gear to a shaft that rotates integrally with the plastic gear. The connection structure is characterized by the following arrangements. The arrangements specifically include: a mortise is provided at a central portion of a rectangular set plate; a rectangular recessed portion, in which the set plate fits, is provided on a front surface of a portion of the plastic gear, to which the shaft is connected, and the set plate is thereby mounted; a tenon, which is to be passed through the mortise provided m the set plate, is provided on the side of an end of the shaft, at which the gear is connected; the tenon is set to have such a length that, when the plastic gear is to be connected to the shaft, the mortise is first aligned with the tenon and then a step of mounting the tenon in the mortise is proceeded, and when the mounting step of the tenon in the mortise is proceeded a predetermined amount, the plastic gear is meshed with the mating gear. [Effect of the Invention] The connection structure between a plastic gear and a shaft according to the present invention permits transmission of a driving force through a large area of contact produced between the set plate and the recessed portion. This enhances durability of the plastic gear. The connection structure also allows the plastic gear and the mating gear to be meshed with each other after phase matching of an oil pump rotor is performed with the plastic gear yet to be in mesh with the mating gear. This enhances efficiency in phase matching and assembly work. The subject invention relates to a connection structure between a plastic gear and a shaft for connecting a plastic gear that meshes with a drive gear or a driven gear or a shaft that rotates integrally with the plastic gear, comprising: a mortise provided at a central portion of a rectangular set plate; a rectangular recessed portion in which the set plate fits and mounted, provided on a front surface of a portion of the plastic gear, to which the shaft is connected; and a tenon, which is to be passed through the mortise provided in the set plate and is provided on the side of an end of the shaft, at which the gear is connected; wherein the tenon is set to have such a length that, when the plastic gear is to be connected to the shaft, the mortise is first aligned with the tenon and then a step of mounting the tenon is the mortise is proceeded, and when the mounting step of the tenon in the mortise is proceeded a predetermined amount, the plastic gear is meshed with the mating gear. [Brief Description of the Accompaying Drawings] [0024] [FIG. 1] FIG. 1 is a longitudinal cross sectional view showing an air-cooled internal combustion engine for a motorcycle according to the present invention, as viewed from a right-hand side. [FIG. 2] FIG. 2 is a cross sectional view taken along line II-II of FIG. 1. [FIG. 3] FIG. 3 is a cross sectional view taken along line III-III of FIG. 1, showing a right-hand half portion inside a crankcase. [FIG. 4] FIG. 4 is a cross sectional view taken along line IV-IV of FIG. 3. [Best Mode for Carrying Out the Invention] FIG. 1 is a longitudinal cross sectional view showing an air-cooled internal combustion engine for a motorcycle according to the present invention, as viewed from a right-hand side. FIG. 1 shows, by removing a right case cover of a transmission, positions of a rotating shaft that protrudes to a right-hand side of a right crankcase and a number of different gears. FIG. 2 is a cross sectional view taken along line II-II of FIG. 1. Referring to FIGS. 1 and 2, a crankcase assembly includes a left case cover 1, a left crankcase 2, a right crankcase 3, and a right case cover 4. A cylinder block 5, a cylinder head 6, and a cylinder head cover 7 are connected to an upper portion of the crankcase assembly. A reference numeral 10 represents a crankshaft. A reference numeral 11 represents a main shaft of the transmission. A reference numeral 12 represents a countershaft of the transmission. A reference numeral 13 represents a kick starter shaft. A reference numeral 14 represents the position of a center of rotation of a shift drum. A reference numeral 15 represents a transmission shifter. A reference numeral 16 represents a balancer shaft. A reference numeral 17 represents an oil pump shaft. A reference numeral 18 represents a crankpm. A reference numeral 19 represents a connecting rod connected to the crankpin 18. A reference numeral 20 represents a piston connected to the connecting rod 19, making vertical movements in the cylinder block 5. Referring to FIG. 2, the crankshaft 10 is rotatably supported by the left crankcase 2 and the right crankcase 3 through a ball bearing 21 and a roller bearing 22, respectively. The main shaft 11 and the countershaft 12 of the transmission are also supported by the left crankcase 2 and the right crankcase 3 through respective ball bearings. The kick starter shaft 13 is supported by the right crankcase 3 and the right case cover 4. The countershaft 12 is an output shaft of this internal combustion engine. A drive sprocket 23 is provided on a portion protruding outwardly from the left crankcase 2. The drive sprocket 23 thus drives a rear wheel of the motorcycle through a chain 24. An alternator 39 is provided on a left end portion of the crankshaft 10. A balancer drive gear 25 and a shared drive gear 26 are secured through a key 27 to a right-hand portion of the crankshaft 10 The balancer drive gear 25 meshes with a balancer driven gear 37 (FIG 1) . The shared drive gear 26 meshes with a main shaft driven gear 28 on the main shaft 11 and an oil pump driven gear 44 on the oil pump shaft 17 (FIG. 1). The mam shaft driven gear 28 is fitted to a right-hand side portion of the main shaft 11 The main shaft driven gear 28 is m constant mesh with the shared drive gear 26 and circumferentially rotatable relative to the mam shaft 11. A multiple disc clutch 30 is provided on a right end of the main shaft 11 The multiple disc clutch 30 is normally engaged, but disengaged when an operating mechanism 29 is operated. A clutch outer 31 of the multiple disc clutch 30 is secured to the mam shaft driven gear 28. A clutch inner 32 is secured to the mam shaft 11. Rotation of the crankshaft 10 is transmitted to the main shaft driven gear 2 8 through the shared drive gear 26, and to the mam shaft 11 through the multiple disc clutch 30. Referring to FIG. 2, transmission gears 33 are provided for the mam shaft 11 and the countershaft 12. The transmission gears 33 include five gears provided on the main shaft 11 and another five gears provided on the countershaft 12 and in constant mesh with the five gears on the main shaft 11. A total of ten of these gears are classified into any of the following three categories: (a) those secured to the shaft, (b) those held in position by the shaft through a plain bearing that are circumferentially rotatable relative to the shaft, but not movable axially, and (c) those held in position by the shaft through a spline that are axially movable, but not circumferentially rotatable relative to the shaft. [0013] The axially movable gears classified m category (c) make up a dog clutch. A axially movable gear is moved axially by a shift fork (not shown) that is m constant engagement therewith. The axially movable gear is thereby engaged with a circumferentially rotatable gear classified into category (b), thus locking the gear in category (b) relative to the shaft. Through the operations described above, one pair of gears capable of transmitting drive is selectively made to enable gearshift from a 1st speed up to a 5th speed. A gear 34 on the kick starter shaft 13 can start to rotate the crankshaft 10 through a gear 35 on a right end portion of the countershaft 12, a gear 3 6 on a right end portion of the mam shaft 11, the mam shaft driven gear 28, and the shared drive gear 26 on the crankshaft 10. FIG. 3 is a cross sectional view taken along line III-III of FIG. 1, showing a right-hand half portion inside the crankcase. The right-hand half portion of the crankshaft 10 is supported on the right crankcase 3 through the roller bearing 22. A bushing 38 is interposed between the right crankcase 3 and the roller bearing 22. As described earlier, the balancer drive gear 25 and the shared drive gear 2 6 are mounted through the shared key 27 to the crankshaft 10. An oil pump 40 is provided downward the crankshaft 10. A pump case 41 is mounted on the right crankcase 3 through a steel plate 42, being secured thereto with a bolt 43. An oil pump shaft 17 is rotatably supported by the right crankcase 3 and a wall body of the pump case 41 One end of the oil pump shaft 17 passes through the wall body of the pump case 41, protruding rightwardly to form a rightward protruding portion. A plastic oil pump driven gear 44 is secured to the rightward protruding portion of the oil pump shaft 17 by way of a tenon 17a on a leading end of the oil pump shaft 17 and a set plate 45. The plastic oil pump driven gear 44 meshes with the shared drive gear 26. The set plate 45 is fitted into a set plate mounting recessed portion 44a provided on a front surface of the oil pump driven gear 44. The tenon 17a on the leading end of the oil pump shaft 17 is fitted in a mortise 45a at a central portion in the set plate 45. An oil pump rotor 46 is fitted over the oil pump shaft 17. As the crankshaft 10 rotates, the oil pump rotor 46 is rotated through the shared drive gear 26, the oil pump driven gear 44, the set plate 45, the tenon 17a, and the oil pump shaft 17. FIG. 4 is a cross sectional view taken along line IV-IV of FIG. 3, showing the crankshaft 10, the main shaft 11, the balancer shaft 16, and the tenon 17a on the leading end of the oil pump shaft 17. The shared drive gear 26 on the crankshaft 10 meshes with the main shaft driven gear 28 on the main shaft 11 and the plastic oil pump driven gear 44 on the oil pump shaft 17. The balancer drive gear 25 on the crankshaft 10 meshes with the balancer driven gear 37 on the balancer shaft 16. Referring to FIG. 4, the set plate 45 for inhibiting relative rotation is interposed between the plastic oil pump driven gear 44 and the oil pump shaft 17. The set plate 45 is a rectangular steel plate provided at the center thereof with the mortise 45a having two faces running in parallel with each other. The set plate mounting recessed portion 44a of a rectangular shape, in which the set plate 45 fits, is provided on the front surface at the portion of the plastic oil pump driven gear 44, at which the oil pump shaft 17 is connected. The set plate 45 fits into this set plate mounting recessed portion 44a. A driving force from the plastic oil pump driven gear 44 is transmitted through four faces around the set plate mounting recessed portion 44a and surfaces of the set plate 45, on which the four faces of the set plate mounting recessed portion 44a abut. The oil pump shaft 17 is a shaft made of steel. The tenon 17a is provided on the end of the oil pump shaft 17 to be connected to the oil pump driven gear 44. The tenon 17a is to be fitted into the mortise 45a in the set plate 45. The tenon 17a on the end of the shaft has a cross section of the same shape as a cross section of the mortise 45a in the set plate 45. Specifically, the tenon 17a includes two surfaces that run in parallel with, and abut on, the two parallel surfaces of the mortise 45a in the set plate 45. A driving force from the set plate 45 is transmitted to the oil pump shaft 17 through these parallel abutment surfaces. The tenon 17a is set to have such a length that, when the plastic oil pump driven gear 44 is to be connected to the oil pump shaft 17, the mortise 45a is first aligned with the tenon 17a and then a step of mounting the tenon 17a in the mortise 45a is proceeded, and when the mounting step is proceeded a predetermined amount, the plastic oil pump driven gear 44 is meshed with the mating shared drive gear 26 The connection structure between the plastic gear and the shaft according to the preferred embodiment of the present invention is arranged as described in the foregoing. The set plate 45 has the four faces therearound to be in contact with the plastic gear 44, which allows the driving force of the gear to be transmitted to the set plate 45 through the four faces. The arrangement according to the preferred embodiment of the present invention has a greater pressure receiving surface as compared with the lock pin described under Prior Art. This allows a surface pressure to be reduced, thus resulting in durability of the plastic gear 44 being enhanced, Assembly steps proceed as follows when assembling the oil pump 40, the oil pump shaft 17, and the plastic oil pump driven gear 44 using the connection structure between the plastic gear and the shaft according to the preferred embodiment of the present invention. Specifically, with the tenon 17a aligned with the mortise 45a and with the plastic oil pump driven gear 44 not in mesh with the shared drive gear 26, a step of mounting the plastic oil pump driven gear 44 together with the set plate 45 is proceeded relative to the tenon 17a in the oil pump shaft 17. Then, the plastic oil pump driven gear 44 is meshed with the shared drive gear 26. The tenon 17a is set to have a relatively long dimension as described in the foregoing. This allows phase matching between the oil pump driven gear and the oil pump shaft to be performed when the plastic oil pump driven gear 44 is yet to be in mesh with the shared drive gear 26. This enhances efficiency in phase matching work. According to the prior art arrangement, the lock pin used as a locking member interposed between the oil pump driven gear and the oil pump shaft is passed through the oil pump shaft. This makes it not necessarily easy to bring gears into mesh with each other after phase matching of the oil pump rotor has been performed. In accordance with the preferred embodiment of the present invention, on the other hand, the set plate 45 is used as the locking member and, unlike the prior art arrangement, the oil pump shaft 17 (the tenon 17a on the leading end thereof) is passed through the locking member (set plate 45) . This allows the axial position of the oil pump driven gear to be freely changed relative to the axial position of the oil pump shaft. This makes it possible to first perform phase matching between the oil pump driven gear and the oil pump shaft and then to bring the oil pump driven gear into mesh with the drive gear. This enhances efficiency in pump and gear assembly work [Description of the Reference Numerals] 1 ... LEFT CASE COVER 2 ... LEFT CRANKCASE 3 ... RIGHT CRANKCASE 4 ... RIGHT CASE COVER 5 ... CYLINDER BLOCK 6 ... CYLINDER HEAD 7 ... CYLINDER HEAD COVER 10 ... CRANKSHAFT 11 ... MAIN SHAFT 12 ... COUNTERSHAFT 13 ... KICK STARTER SHAFT 14 ... POSITION OF CENTER OF ROTATION OF SHIFT DRUM 15 ... TRANSMISSION SHIFTER 16 ... BALANCER SHAFT 17 ... OIL PUMP SHAFT 17a ... TENON 18 ... CRANKPIN 19 ... CONNECTING ROD 2 0 ... PISTON 21 ... BALL BEARING 22 ... ROLLER BEARING 23 ... DRIVE SPROCKET 24 ... CHAIN 25 ... BALANCER DRIVE GEAR 2 6 ... SHARED DRIVE GEAR 27 ... KEY 2 8 ... MAIN SHAFT DRIVEN GEAR 2 9 ... OPERATING MECHANISM 3 0 ... MULTIPLE DISC CLUTCH 31 ... CLUTCH OUTER 32 ... CLUTCH INNER 3 3 ... TRANSMISSION GEARS 34 ... KICK STARTER SHAFT GEAR 3 5 ... GEAR ON RIGHT END PORTION OF COUNTERSHAFT 3 6 ... GEAR ON RIGHT END PORTION OF MAIN SHAFT 3 7 ... BALANCER DRIVEN GEAR 3 8 ... BUSHING 3 9 ... ALTERNATOR 4 0 ... OIL PUMP 41 ... PUMP CASE 42 ... STEEL PLATE 43 ... BOLT 44 ... OIL PUMP DRIVEN GEAR 44a ... SET PLATE MOUNTING RECESSED PORTION 45 ... SET PLATE 4 5a ... MORTISE 4 6 ... OIL PUMP ROTOR We Claim: 1. A connection structure between a plastic gear and a shaft for connecting a plastic gear that meshes with a drive gear or a driven gear or a shaft that rotates integrally with the plastic gear, comprising: a mortise provided at a central portion of a rectangular set plate; a rectangular recessed portion in which the set plate fits and mounted, provided on a front surface of a portion of the plastic gear, to which the shaft is connected; and a tenon, which is to be passed through the mortise provided in the set plate and is provided on the side of an end of the shaft, at which the gear is connected; wherein the tenon is set to have such a length that, when the plastic gear is to be connected to the shaft, the mortise is first aligned with the tenon and then a step of mounting the tenon in the mortise is proceeded, and when the mounting step of the tenon in the mortise is proceeded a predetermined amount, the plastic gear is meshed with the mating gear. 2. A connection structure between a plastic gear and a shaft substantially as herein described with reference to the accompanying drawings.

Documents:

1363-del-2004-abstract.pdf

1363-del-2004-claims cancelled.pdf

1363-del-2004-claims.pdf

1363-del-2004-complete specification(granted).pdf

1363-del-2004-correspondence-others.pdf

1363-del-2004-correspondence-po.pdf

1363-del-2004-description (complete).pdf

1363-del-2004-drawings.pdf

1363-del-2004-form-1.pdf

1363-del-2004-form-19.pdf

1363-del-2004-form-2.pdf

1363-del-2004-form-3.pdf

1363-del-2004-form-5.pdf

1363-del-2004-gpa.pdf

1363-del-2004-petition-137.pdf

1363-del-2004-petition-138.pdf

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