JP4144213B2 - Motorcycle transmission - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a transmission for a motorcycle.
[0002]
[Prior art]
An engine mounted on a small vehicle such as a motorcycle is equipped with a transmission. This transmission includes a countershaft to which rotation of a crankshaft is transmitted via a clutch mechanism, and a driveshaft that transmits rotation to a rear wheel, which is a drive wheel, via a drive chain, for example. The primary deceleration is performed by providing a plurality of different transmission gears and changing the combination of these transmission gears.
[0003]
As a structure of the shift mechanism that changes the combination of the transmission gears, for example, the shift cam is rotated by shifting the change pedal arm, and the shifter fork is slid in the axial direction by the rotation of the shift cam. A structure to be moved is common.
[0004]
Further, as a method for transmitting the shift operation of the change pedal arm to the shift cam, for example, a link type shift cam driving method as shown in Japanese Patent Laid-Open No. 62-177339 or a gear type as shown in Japanese Patent Laid-Open No. 6-123355. The shift cam drive system is generally used. In both methods, a link that transmits the shift pedal arm shift operation to the shift cam and a stopper pin that restricts the operating range of the gear are provided, and the shift cam is positioned to give a sense of moderation during the shift operation. Means for doing so are also provided.
[0005]
In the case of the above-described link type shift cam drive system, the stopper pin is provided outside the operating range of the link (shift lever 2), and the shift cam positioning means (stopper 14) is on the opposite side of the link in side view across the shift cam. Is provided.
[0006]
On the other hand, in the gear type shift cam drive system described above, the stopper pin (stopper 24) is provided within the operating range of the gear (shift drive gear 21), but the shift cam positioning means (cam stopper 40) sandwiches the shift cam. And provided on the opposite side of the gear in plan view.
[0007]
[Problems to be solved by the invention]
However, in recent years, there has been a demand for downsizing of the engine, and it is not preferable to dispose the stopper pin and the shift cam positioning means apart from each other as in the conventional example described above.
[0008]
Further, since mission gears, shafts, oil pans, and the like are densely arranged in the vicinity of the shift mechanism, it is difficult to arrange the stopper pin and the positioning means for the shift cam in the layout.
[0009]
The present invention has been made in consideration of the above-described circumstances, and an object of the present invention is to provide a transmission for a motorcycle in which a shift mechanism is made compact.
[0010]
[Means for Solving the Problems]
In order to solve the above-described problems, a transmission for a motorcycle according to the present invention is as described in claim 1. A crankcase that is partitioned by a partition into a crank chamber in which the crankshaft is housed and a transmission chamber in which the transmission mechanism is housed, and a lubricating oil that is disposed in the crank chamber and accumulates at the bottom on the crank chamber side. A pumping oil pump for introducing lubricating oil into the transmission chamber, and a lubricating oil pump for guiding the lubricating oil after the transmission mechanism lubrication accumulated at the bottom of the transmission chamber to the crankshaft and the like in the crank chamber The shift cam is rotated by shifting the change pedal arm for the foot movement operation, and the shift cam is slid in the axial direction by the rotation of the shift cam, so that a plurality of shafts provided between the counter shaft and the drive shaft in the mission chamber are provided. Mission gear Changing the combination In a motorcycle transmission equipped with a shift mechanism, The shift mechanism includes a change arm that swings around a change pedal shaft by a shift operation of the change pedal arm, a shift cam driven gear that meshes with a gear provided on the free end side of the change arm, and a relative rotation with the shift cam driven gear. A shift cam that is freely disposed in parallel with the change pedal shaft, a positioning cam that is rotatably integrated with the shift cam, a shift cam positioning unit that is swingably disposed and engageable with the positioning cam, and a shift cam positioning unit The motorcycle includes a swing range restricting means that is provided coaxially with the swing fulcrum and restricts the swing range of the change arm. Part and a mounting part located on the overlapping part. A lower part of a crank wheel provided at a substantially central part of the crankshaft is disposed behind the front part, and the shift mechanism is disposed below the counter shaft and the drive shaft disposed in the transmission chamber located behind the crank wheel. Place It is a thing.
[0011]
Further, in order to solve the above-described problem, as described in claim 2, the stopper pin is moved between the swing arm of the change arm, that is, between the change pedal shaft and the shift cam, and the swing of the change arm. It is arranged within the range.
[0012]
Furthermore, in order to solve the above-described problem, as described in claim 3, the stopper pin is a straight line connecting the center of the change pedal shaft and the shift cam shaft that is coaxially and integrally fixed with the shift cam. It is arranged above.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0015]
FIG. 1 is a left side view showing an example of a motorcycle to which the present invention is applied. FIG. 2 is an enlarged left side view of the center portion of the vehicle body. FIG. 3 is an enlarged right side view of the vehicle body central portion. As shown in FIGS. 1, 2, and 3, the motorcycle 1 includes a body frame 2 of a semi-double cradle frame type, for example. The vehicle body frame 2 mainly includes a head pipe 3, a tank rail 4, a down tube 5, an under tube 6, a main tube 7, a rear pipe 8 and a seat rail 9.
[0016]
A head pipe 3 is provided at the front head of the vehicle body frame 2, and the tank rail 4 extends obliquely downward from the rear upper part of the head pipe 3. A down tube 5 extends substantially downward from the rear lower portion of the head pipe 3, and an under tube 6 is connected to the lower end of the down tube 5. The undertube 6 forms a pair on the left and right and extends downward once, and is bent backward in the middle and then extends substantially horizontally. In addition, upper ends of a pair of left and right main tubes 7 are connected to the rear end of the tank rail 4 from side to side. These main tubes 7 extend substantially downward and are connected to the rear ends of the under tubes 6.
[0017]
On the other hand, the front ends of a pair of left and right seat rails 9 are connected to the rear end of the tank rail 4, and the pair of left and right rear pipes 8 extend forward and downward from the vicinity of the center of the seat rail 9 toward the lower portion of the main tube 7. Established.
[0018]
An engine 10 is mounted at the center lower portion of the body frame 2. As shown in FIGS. 2 and 3, the engine 10 is fixed to the vehicle body frame 2 at three locations, that is, an upper front portion, a lower front portion, and a rear portion. Specifically, the upper front portion of the engine 10 is fixed to the down tube 5 via the stay 11, and the mount portion 10 a below the front portion of the engine 10 is sandwiched between bent portions of the left and right under tubes 6. .
[0019]
Furthermore, the rear part of the engine 10 is sandwiched between the left and right main tubes 7, and each attachment part forms a substantially isosceles triangle in a side view. The engine 10 is disposed such that the bottom surface is above the lower surface of the undertube 6, and the lower portion of the engine 10 and the horizontal portion of the undertube 6 are overlapped in a side view. A mount portion 10a on the lower side of the front portion of the engine 10 is disposed in front of the portion. A fuel tank 12 is installed above the tank rail 4, and an operation seat 13 and a rear fender 14 are fixed to the seat rail 9.
[0020]
The head pipe 3 is provided with a steering mechanism 15. The steering mechanism 15 is provided with a front fork 17 and a handle bar 18 that rotatably support the front wheel 16, and is pivotally attached to the left and right. On the other hand, a swing arm 20 is pivotally mounted around a pivot shaft 19 on a pivot shaft 19 (the same position as the sandwiched portion of the rear portion of the engine 10) erected on the lower portion of the main tube 7 and is driven at the rear end portion. A rear wheel 21 that is a wheel is pivotally supported.
[0021]
4 is a cross-sectional view taken along line IV-IV in FIG.
[0022]
As shown in FIGS. 1 to 4, the engine 10 is, for example, a four-cycle single-cylinder engine, and a cylinder assembly 25 including a head cover 22, a cylinder head 23, and a cylinder block 24 in order from the top is slightly on the engine case 26. Placed in a tilted state.
[0023]
The engine case 26 mainly includes left and right crankcases 27 that are divided into two in the vehicle width direction, a clutch housing 28 that is disposed on the right side surface of the crankcase 27, and a generator that is disposed on the left side surface of the crankcase 27. And a cover 29. The clutch housing 28 and the generator cover 29 are disposed above the horizontal portion of the undertube 6 and project outwardly in the vehicle width direction.
[0024]
Further, the engine 10 is provided with a double overhead cam that opens and closes the valves 30 and 31 by providing two camshafts 32 for opening and closing the intake valve 30 and the exhaust valve 31 above the cylinder head 23. This is a four-cycle engine including a shaft (DOHC) type valve operating mechanism 33.
[0025]
An exhaust pipe 34 and a muffler 35 constituting an engine exhaust system are connected to the front portion of the cylinder assembly 25. A carburetor 36 constituting an engine intake system is connected to the rear portion of the cylinder assembly 25, and an air cleaner 37 disposed below the operation seat 13 is connected to the upstream side of the carburetor 36. A pair of left and right radiators 38 constituting an engine cooling system are disposed at the rear lower part of the head pipe 3 and the front upper part of the engine 10.
[0026]
As shown in FIGS. 2 to 4, the interior of the crankcase 27 is divided forward and backward by a partition wall 39, and a crank chamber 40 is formed in the front and a mission chamber 41 is formed in the rear.
[0027]
A crankshaft 42 is disposed in the crank chamber 40 at a right angle to the width direction of the vehicle, that is, the traveling direction of the vehicle. The crankshaft 42 is arranged so that a lower portion of a crankwheel 42a provided at a substantially central portion thereof is located behind the mount portion 10a on the lower front portion of the engine 10.
[0028]
Further, a cylinder bore 44 that accommodates the piston 43 is formed inside the cylinder block 24, and a combustion chamber 45 that is aligned with the cylinder bore 44 is formed in the cylinder head 23, and toward the combustion chamber 45 from the outside. A spark plug 46 is inserted.
[0029]
A large end portion 48 a of a connecting rod 48 is connected to the crank pin 47 located at a substantially central portion of the crankshaft 42, and a piston 43 is connected to a small end portion 48 b of the connecting rod 48. The piston 43 reciprocates in the cylinder bore 44 in the axial direction, and the reciprocating stroke is transmitted to the crankshaft 42 via the connecting rod 48 to rotate the crankshaft 42.
[0030]
On the other hand, a transmission mechanism 49, which is a reduction gear, is provided in the mission chamber 41 located behind the crank wheel 42a. The transmission mechanism 49 is disposed in parallel with the crankshaft 42, and is a countershaft 51 to which driving force from the crankshaft 42 is input via the clutch mechanism 50, and a driving shaft that outputs driving force to the rear wheels 21. A drive shaft 52 is provided.
[0031]
On the other hand, a pair of oil pumps 93 and 94 are accommodated in the crank chamber 40. One of the oil pumps 93 and 94 is a scavenge pump 93 for pumping up, and the other is a feed pump 94 for lubrication. The scavenge pump 93 pumps up the lubricating oil accumulated at the bottom on the crank chamber 40 side. Lubricating oil is dropped on each part of the mechanism 49. Further, the feed pump 94 lubricates each part of the transmission mechanism 49 in the mission chamber 41 and lubricates the lubricating oil accumulated at the bottom on the mission chamber 41 side to each part of the crankshaft 42, the piston 43, and the valve mechanism 33 in the crank chamber 40. Lead.
[0032]
A primary drive gear 53 is provided integrally with one end of the crankshaft 42, that is, the right end in the present embodiment, and a primary driven gear 54 that meshes with the primary drive gear 53 is rotatable on the countershaft 51. The primary driven gear 54 is fixed to the clutch main body 55 of the clutch mechanism 50 so as to rotate together and transmits the rotational driving force of the crankshaft 42 to the clutch mechanism 50.
[0033]
Further, the countershaft 51 and the drive shaft 52 are provided with a plurality of transmission gears 56 and 57 having different numbers of teeth to constitute a transmission 58, and the combination of these transmission gears 56 and 57 is changed to perform primary deceleration. Is going.
[0034]
One end of the drive shaft 52 protrudes outside the mission chamber 41, and a drive sprocket 59 is provided at the end of the projecting drive shaft 52. The drive sprocket 59 is connected to a driven sprocket 61 provided on the rear wheel 21 via a drive chain 60, and performs secondary deceleration by this chain drive to transmit the engine driving force to the rear wheel 21.
[0035]
A cam drive gear 62 is provided at the left end of the crankshaft 42. In addition, cam sprockets 63 are provided at one ends of the respective camshafts 32 arranged in the cylinder head 23, and these cam sprockets 63 are operatively connected to the cam drive gear 62 via cam chains 64. Rotation is transmitted to the camshaft 32 via the cam chain 64, so that the valve mechanism 33 operates.
[0036]
The clutch housing 28 is disposed on the right side surface of the crankcase 27, and the clutch main body 55 is accommodated in the rear interior thereof. The clutch main body 55 accommodating portion of the clutch housing 28 is opened sideways. The clutch cover 65 is detachable.
[0037]
FIG. 5 is a right side view of the crankcase 27 with the clutch housing 28 removed. 6 is a cross-sectional view taken along line VI-VI in FIG. 5, and FIG. 7 is a cross-sectional view taken along line VII-VII in FIG.
[0038]
As shown in FIGS. 4 to 7, the transmission 58 configured to change speed by changing the combination of the transmission gears 56 and 57 provided on the counter shaft 51 and the drive shaft 52 includes the shafts 51 and 52. And four transmission gears, each having four transmission gears 56 and 57. The transmission 58 includes a shift mechanism 66 that is a means for changing the combination of the transmission gears 56 and 57 in addition to the transmission gears 56 and 57 described above below the shafts 51 and 52.
[0039]
Of the transmission gears 56 and 57, one shaft, in this embodiment, the four drive transmission gears 56 provided on the countershaft 51 are all fixed to the countershaft 51 so as to rotate together and not move in the axial direction. The
[0040]
Further, of the transmission gears 56 and 57, the other shaft, that is, the four driven transmission gears 57 provided on the drive shaft 52 in the present embodiment are all provided on the drive shaft 52 so as to be freely rotatable, and also by a circlip 69. It is set so as not to move in the axial direction, and is always meshed with the drive mission gear 56.
[0041]
Further, a slider 70 is disposed between the two left driven mission gears 57 and the two right driven gears 57 on the drive shaft 52. The slider 70 is provided so as to rotate integrally with the drive shaft 52 and to be slidable in the axial direction by, for example, a spline.
[0042]
Further, dogs 71 are formed on both end surfaces of the slider 70 in the axial direction, and dogs 72 that can be engaged with the dogs 71 of the sliders 70 are also formed on the side surfaces of the driven mission gear 57 that the dogs 71 face. Further, an outer peripheral groove 74 in which a shifter fork 73 constituting a shift mechanism 66 described later can be engaged is formed on the outer peripheral surface of the slider 70 positioned between the dogs 71 at both ends of the slider 70. The slider 70 is set so that the outer diameter thereof is smaller than the inner diameter dimension of the tooth portion of the driven gear 57 that is adjacent to the slider 70.
[0043]
As shown in FIGS. 5 to 7, the shift mechanism 66 mainly includes a change pedal arm 75, a change pedal shaft 76, a change arm 77, a shift cam 78, a shifter fork 73, and a shifter fork shaft 79.
[0044]
Below the countershaft 51, a shift cam 78 disposed in parallel with the countershaft 51 is pivotally supported. The shift cam 78 is, for example, a cylindrical cam cast in a hollow shape, and two lead grooves 78a are formed on the outer peripheral surface thereof.
[0045]
On the other hand, a change pedal shaft 76 is disposed in the lower rear part of the crankcase 27 in parallel with the counter shaft 51 and the drive shaft 52. The left end portion of the change pedal shaft 76 protrudes outside the crankcase 27, and the base end portion of the change pedal arm 75 for foot movement operation is attached to the protruding portion. Further, the base end portion of the change arm 77 is attached to the right end portion of the change pedal shaft 76, and the change arm 77 swings in the vertical direction about the change pedal shaft 76. Then, the gear 77 a provided on the free end side of the change arm 77 always meshes with the shift cam driven gear 80 provided on the right end of the shift cam 78, and the shift cam 78 is rotated by the shift operation of the change pedal arm 75.
[0046]
Here, the rotation mechanism of the shift cam 78 by the change arm 77 will be described with reference to FIGS. 6 and 7 and FIG. 8 which is an enlarged side view of the main part of the shift mechanism 66. As shown in FIGS. 6 and 7, a pole housing 81 is fixed to the right end of the shift cam 78 coaxially by a shift cam shaft 82 so as to rotate together.
[0047]
A pole holder 83 is disposed on the right side of the pole housing 81, and the shift cam driven gear 80 is press-fitted to the right end of the pole holder 83, for example. Retained. The pole holder 83 and the pole housing 81 are allowed to rotate relative to each other, and a positioning cam 84 is formed on the outer peripheral surface of the pole housing 81.
[0048]
A pair of pole storage portions (not shown) are formed on the outer peripheral surface of the pole holder 83, and the poles 85 are stored in these pole storage portions. One end of the pole 85 is pivotally mounted in the pole housing portion of the pole holder 83 so as to be swingable, and the other end is spring-biased so as to protrude outward in the radial direction of the pole holder 83. And a pair of pole 85 is arrange | positioned in the opposing position on both sides of the rotation center of the pole holder 83, and each protrudes toward the opposite direction.
[0049]
On the other hand, on the inner peripheral surface of the pole housing 81, a plurality of engaging recesses 86 that can engage with the free ends of the poles 85 protruding outward in the radial direction of the pole holder 83 are formed at equal intervals. The rotation of the shift cam driven gear 80 and the pole holder 83 is transmitted to the pole housing 81 and the shift cam 78 with the free end of the pole 85 engaged with the mating recess 86.
[0050]
A pole lifter 87 is provided on the outer periphery of the pole 85 provided in the pole holder 83. The pole lifter 87 releases the engagement between the engagement recess 86 and the pole 85 by pushing the pole 85 into the pole housing portion on the outer peripheral surface of the pole holder 83 when the pole 85 moves to a predetermined position. Is released, the rotation of the shift cam driven gear 80 and the pole holder 83 transmitted to the pole housing 81 and the shift cam shaft 82 is interrupted.
[0051]
On the other hand, an opening 77 b is formed in the substantially central portion of the change arm 77, and the change pedal shaft 76 that is the swing fulcrum of the change arm 77 and the shift cam 78 are coaxial within the swing range of the change arm 77. A stopper pin 88, which is a means for restricting the swing range of the change arm 77 in the vertical direction, is formed in parallel with both shafts on the straight line connecting the shift cam shaft 82 and the center of both shafts. In addition, it is disposed in a state facing the opening 77 b of the change arm 77, and is fixed to a boss portion 27 a formed on the crankcase 27.
[0052]
A return spring 89 is interposed between the change pedal shaft 76 and the change arm 77, and the change arm 77 returns to its swing neutral position by holding the stopper pin 88 between the free ends of the return spring 89. Is done.
[0053]
On the other hand, a boss portion 27 a formed on the crankcase 27 is provided with a proximal end portion of a positioning arm 90 which is a positioning means of the shift cam 78 so as to be rotatable coaxially with the stopper pin 88. The positioning arm 90 gives a sense of moderation during the shifting operation, and is provided at its free end by a return spring 92 wound around a boss portion 27a and a stopper pin 88 as a swing fulcrum of the positioning arm 90. The roller 91 is constantly pressed against a positioning cam 84 formed on the outer peripheral surface of the pole housing 81.
[0054]
On the other hand, a shifter fork shaft 79 is disposed between the shift cam 78 and the drive shaft 52 in the vicinity of the shift cam 78. The shifter fork shaft 79 is disposed in parallel with the drive shaft 52 and on a straight line connecting the centers of the shift cam 78 and the drive shaft 52.
[0055]
The shifter fork shaft 79 has a plurality of Y-shaped base ends of two shifter forks 73 in this embodiment. The base end portions of the shifter fork shafts 79 are slidable in the axial direction, and project to the base end portions of the shifter forks 73. The provided guide pins 73a are slidably fitted into the lead grooves 78a of the shift cam 78, respectively.
[0056]
The fork portions 73b formed at the free ends of the shifter forks 73 engage with the outer peripheral grooves 74 of the sliders 70 provided on the drive shaft 52, respectively, and grip these sliders 70 in a rotatable manner.
[0057]
As described above, FIG. 8 is an enlarged side view of the main part of the shift mechanism 66, showing the state where the change pedal arm 75 is in the neutral position. FIG. 9 shows a state in which the change pedal arm 75 is being operated (in the middle of kicking up), and FIG. 10 shows a state in which the change pedal arm 75 is in the maximum operating state (at the time of maximum kicking up).
[0058]
In a state where the change pedal arm 75 is not shifted (pick-up operation), the change arm 77 is maintained at the swing neutral position by a return spring 89 that holds the stopper pin 88 as shown in FIG.
[0059]
When the change pedal arm 75 is started to shift (kick up operation), as shown in FIG. 9, the change arm 77 swings upward, for example, around the change pedal shaft 76 and moves to the free end side of the change arm 77. The provided gear 77a rotates the shift cam driven gear 80, which is held so as to be relatively rotatable around the shift cam shaft 82, for example, clockwise in a side view.
[0060]
When the shift cam driven gear 80 rotates, the pole holder 83 also rotates at the same time. At this time, one of the poles 85 disposed at the opposite position across the rotation center of the pole holder 83 is stored in the pole holder 83 on the outer peripheral surface of the pole holder 83 by the pole lifter 87. The other pole 85 engages with an engagement recess 86 formed on the inner peripheral surface of the pole housing 81, and the rotation of the pole holder 83 is transmitted to the pole housing 81 and the shift cam 78.
[0061]
As the pole housing 81 rotates, the positioning cam 84 formed on the outer peripheral surface of the pole housing 81 also rotates, and the cam arm 84a causes the positioning arm 90 to move, for example, obliquely downward about the stopper pin 88. It is swung.
[0062]
As shown in FIG. 10, when the shift operation of the change pedal arm 75 proceeds and the shift cam 78 rotates, the shifter fork 73 slides along the shifter fork shaft 79 along the lead groove 78a of the shift cam 78, As a result, the slider 70 slides along the axial direction of the drive shaft 52, and the dog 70 is dog-engaged with or separated from the adjacent driven transmission gear 57.
[0063]
When the driven transmission gear 57 and the slider 70 are dog-engaged, the engaged driven transmission gear 57 is rotationally integrated with the drive shaft 52, so that the speed is changed according to the gear ratio of the gear and the output of the engine 10 is changed to the countershaft. 51 is transmitted to the drive shaft 52.
[0064]
At this time, the roller 91 provided at the free end of the positioning arm 90 is fitted into the valley 84b of the positioning cam 84, and the shift cam 78 is positioned.
[0065]
When the shift operation is completed and the force applied to the change arm 77 is released, the change arm 77 is returned to the swing neutral position shown in FIG. 8 by the return spring 89, and the gear 77a of the change arm 77 is shifted to the shift cam driven gear 80. Is turned counterclockwise in a side view.
[0066]
When the shift cam driven gear 80 rotates, the pole holder 83 also rotates in the reverse direction simultaneously. However, since the one pole 85 described above is pushed into the pole housing portion on the outer peripheral surface of the pole holder 83 by the pole lifter 87, this pole 85 is the pole housing. The engaging recess 86 formed on the inner peripheral surface 81 is not engaged, and the rotation of the pole holder 83 is not transmitted to the pole housing 81 and the shift cam 78, and only the pole holder 83 and the shift cam driven gear 80 are shown in FIG. It returns to the swing neutral position shown in
[0067]
Next, the operation of this embodiment will be described.
[0068]
The positioning arm 90 which is a positioning means of the shift cam 78 is provided coaxially with the stopper pin 88 which is a means for restricting the vertical swing range of the change arm 77, and the stopper pin 88 is used as a swing fulcrum of the positioning arm 90. Therefore, it is not necessary to provide a swing fulcrum dedicated to the positioning arm 90. Further, since both are arranged close to each other, the shift mechanism 66 can be made compact, and even the four-cycle engine 10 having a high overall height can keep the overall height low and can be efficiently mounted on the vehicle body frame 2.
[0069]
Further, the stopper pin 88 that is also a swing fulcrum of the positioning arm 90 is disposed between the change pedal shaft 76 that is the swing fulcrum of the change arm 77 and the shift cam 78 and within the swing range of the change arm 77. It is not necessary to secure a space for disposing the stopper pin 88 in the mission chamber 41. As a result, space saving in the mission chamber 41 can be achieved.
[0070]
Furthermore, the stopper pin 88 is arranged on a straight line that connects the center of the change pedal shaft 76 that is the swing fulcrum of the change arm 77 and the shift cam shaft 82 that is coaxially and rotationally fixed to the shift cam 78. The structure of the arm 77 can be simplified, and the shape of the opening 77b formed at the substantially central portion of the change arm 77 can be made symmetrical and the shape can be simplified.
[0071]
Further, since the shift mechanism 66 is made compact, the shift mechanism 66 is disposed inside the portion of the engine 10 that protrudes outward in the vehicle width direction immediately above the portion that overlaps the horizontal portion of the undertube 6. It becomes possible. As a result, the shift mechanism 66 can be efficiently arranged in a limited space, and the position of the lubricating oil accumulated at the bottom of the crankcase 27 and the lower end of the crank wheel 42a can be set low. Center of gravity can be achieved.
[0072]
Further, by making the shift mechanism 66 compact, the positions of the counter shaft 51 and the drive shaft 52 disposed above the shift mechanism 66 can be set low, and the engine height behind the cylinder assembly 25 can be lowered.
[0073]
In the above-described embodiment, the example in which the stopper pin 88 is arranged facing the opening 77b of the change arm 77 has been shown. However, the stopper pin 88 may be disposed within the swing range of the change arm 77 without changing to the opening 77b. It suffices if it is within the region between the pedal shaft 76 and the shift cam 78.
[0074]
【The invention's effect】
As described above, according to the motorcycle transmission according to the present invention, the shift mechanism can be made compact and the height of the engine can be kept low.
[0075]
In addition, the space in the mission room can be saved.
[0076]
Furthermore, the structure and shape of the change arm can be simplified.
[Brief description of the drawings]
FIG. 1 is a left side view of a motorcycle showing an embodiment of a transmission for a motorcycle according to the present invention.
FIG. 2 is an enlarged left side view of a vehicle body central portion.
FIG. 3 is an enlarged right side view of a vehicle body central portion.
4 is a cross-sectional view taken along the line IV-IV in FIG. 3;
FIG. 5 is a right side view of the crankcase with the clutch housing removed.
6 is a sectional view taken along line VI-VI in FIG.
7 is a sectional view taken along line VII-VII in FIG.
FIG. 8 is an enlarged side view of a main part of the shift mechanism in a state where the change pedal arm is in a neutral position.
FIG. 9 is an enlarged side view of a main part of the shift mechanism in the middle of operation of the change pedal arm.
FIG. 10 is an enlarged side view of the main part of the shift mechanism in the maximum operation state of the change pedal arm.
[Explanation of symbols]
1 Motorcycle
2 Body frame
10 engine
10a Engine mount
27 Crankcase
39 Bulkhead
40 Crank chamber
41 Mission Room
42 Crankshaft
42a crank wheel
49 Transmission mechanism
51 countershaft
52 Drive shaft
56,57 mission gear
58 Transmission
66 Shift mechanism
73 Shifter Fork
75 Change pedal arm
76 change pedal shaft
77 Change Arm
77a Gear on the free end of the change arm
78 shift cam
80 Shift cam driven gear
82 Shift camshaft
84 Positioning cam
88 Stopper pin (means to regulate the swing range of the change arm)
89 Change Arm Return Spring
90 Positioning arm (shift cam positioning means)
92 Return spring for positioning arm
93 Scavenge pump (oil pump for pumping)
94 Feed pump (oil pump for lubrication)

Claims (3)

A crankcase that is partitioned by a partition into a crank chamber in which the crankshaft is housed and a transmission chamber in which the transmission mechanism is housed, and a lubricating oil that is disposed in the crank chamber and accumulates at the bottom on the crank chamber side. A pumping oil pump for introducing lubricating oil into the transmission chamber, and a lubricating oil pump for guiding the lubricating oil after the transmission mechanism lubrication accumulated at the bottom of the transmission chamber to the crankshaft and the like in the crank chamber The shift cam is rotated by shifting the change pedal arm for the foot movement operation, and the shift cam is slid in the axial direction by the rotation of the shift cam, so that a plurality of shafts provided between the counter shaft and the drive shaft in the mission chamber are provided. Mission gear In the transmission of a motorcycle having a shift mechanism for changing the combination, the shift mechanism includes a change arm which swings the change pedal shaft axis by a shift operation of the change pedal arm, provided on the free end of the change arm A shift cam driven gear that meshes with the gear, a shift cam that is rotatable relative to the shift cam driven gear and that is disposed in parallel with the change pedal shaft, a positioning cam that is provided integrally with the shift cam, and a swing cam that is rotatably disposed. The motorcycle includes a shift cam positioning means that can be engaged with a cam, and a swing range regulating means that is provided coaxially with a swing fulcrum of the shift cam positioning means and regulates the swing range of the change arm. , Under the front part of the engine And a mount portion disposed on the overlapping portion, and a lower portion of the crank wheel provided at a substantially central portion of the crankshaft is disposed behind the mount portion, and the position located behind the crank wheel. A transmission for a motorcycle, wherein the shift mechanism is disposed below a counter shaft and a drive shaft disposed in a mission chamber .   2. The transmission for a motorcycle according to claim 1, wherein the change arm swing range restricting means is disposed between the change arm swing support point and the shift cam and within the change arm swing range.   3. The change arm swing range restricting means is disposed on a straight line connecting the swing support point of the change arm and the center of the shift cam shaft coaxially and integrally fixed with the shift cam. A transmission for a motorcycle.

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