JPH07304484A - Power transmission device for motorcycle engine - Google Patents

Abstract

PURPOSE:To provide a power transmission device for a motorcycle engine capable of making the whole engine compact, reducing the moment of inertia around the center of gravity, improving the degree of freedom for the vehicle body mounting position, and shortening the center distance. CONSTITUTION:A main shaft 52 and a drive shaft 53 constituting a shift mechanism 51 and a crank shaft 50 are arranged in parallel, and the rotation of the crank shaft 50 is transmitted to a rear wheel 7 from the main shaft 52 via the drive shaft 53 in this power transmission device of a motorcycle engine 10. The main shaft 52 is arranged below the crank shaft 50 and in front of it on a vehicle body. The drive shaft 53 is arranged behind the main shaft 52 and in front of the crank shaft 50 on the vehicle body. An output shaft 54 having a drive sprocket 55 is arranged in parallel with the crank shaft 50, and the output shaft 54 and the pivot shaft 43 of a rear arm 6 are coaxially arranged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arrangement structure of a power transmission shaft in a power transmission device for a motorcycle engine.

[0002]

2. Description of the Related Art Generally, a power transmission device for a motorcycle engine transmits the rotation of a crankshaft from a main shaft, to which a plurality of sets of gear trains constituting a speed change mechanism are mounted, to a drive shaft and takes out from the drive shaft. Sprocket,
It is configured to be transmitted to the rear wheel sprocket via a chain. In such a power transmission device, conventionally, a structure in which the main shaft and the drive shaft are arranged in parallel with the crank shaft and the car body is arranged rearward of the crank shaft is generally used.

[0003]

However, in the above-mentioned conventional arrangement structure of the main shaft and the drive shaft, there is a problem that the length of the engine in the front-rear direction becomes longer and the size becomes larger because the crankcase projects rearward of the vehicle body. . Therefore, the engine weight is dispersed from the center of gravity of the vehicle, the moment of inertia around the center of gravity is likely to be large, and the degree of freedom in the vehicle body mounting position is low.

Further, in the above-mentioned conventional arrangement structure, since the drive shaft is located at the rear, the output shaft is also located at the rear, so that the axial distance between the front wheels and the rear wheels (wheel base) becomes longer and the steering It is disadvantageous in terms of improving sex.

The present invention has been made in view of the above-mentioned conventional situation, and it is possible to reduce the length of the engine in the front-rear direction to make it compact, and by concentrating the weight of the engine on the center of gravity of the vehicle, inertia around the center of gravity is increased. An object of the present invention is to provide a power transmission device for an engine for a motorcycle, which can reduce the moment, improve the degree of freedom in mounting position on the vehicle body, and further reduce the axial distance.

[0006]

According to a first aspect of the present invention, a main shaft and a drive shaft constituting a speed change mechanism are arranged in parallel with a crankshaft, and the crankshaft is rotated from the main shaft via the drive shaft. A power transmission device for a motorcycle engine, which transmits power to a rear wheel, is characterized in that the main shaft is arranged below a crankshaft and in front of a vehicle body.

The invention of claim 2 is characterized in that the drive shaft is arranged behind the main shaft in the vehicle body and in front of the crank shaft in the vehicle body.

According to a third aspect of the present invention, the output shaft having the drive sprocket for transmitting the power from the drive shaft to the rear wheels is arranged in parallel with the crankshaft, and the output shaft and the pivot shaft of the rear arm are arranged in parallel with each other. It is characterized by being coaxial.

[0009]

According to the power transmission device for a motorcycle engine of the first aspect of the present invention, since the main shaft is arranged below the crankshaft and in front of the vehicle body, when the conventional main shaft is arranged behind the crankshaft. In comparison, the length of the engine in the front-rear direction is shortened, whereby the engine weight can be concentrated on the center of gravity of the vehicle, and the moment of inertia around the center of gravity can be reduced. Moreover, since the entire engine can be made compact, the degree of freedom in the vehicle body mounting position can be improved, and the space for arranging engine accessories and the like can be increased.

Further, in the present invention, since the main shaft is arranged in front of the crankshaft, the axial distance between the front wheels and the rear wheels can be shortened, and the maneuverability can be improved accordingly. On the other hand, when the distance between the shafts is the same, the rear arm becomes long, so that the swing angle of the rear arm per constant stroke of the rear wheel can be reduced, and the behavior can be stabilized.

According to the second aspect of the invention, since the drive shaft is arranged behind the main shaft in the vehicle body and in front of the crank shaft in the vehicle body, the length of the engine in the front-rear direction can be further reduced, which contributes to further compactness.

According to the third aspect of the present invention, since the output shaft and the pivot shaft of the rear arm are coaxially arranged, tension of the chain or the like caused by the vertical movement of the rear wheel is avoided while avoiding a long distance between the shafts. Fluctuation can be suppressed. That is, the main shaft,
By disposing the drive shaft in front of the crank shaft, it is possible to avoid the extension of the inter-shaft distance while providing the output shaft separately. Normal,
If the output shafts are provided separately, the output shafts will be positioned rearward, and the distance between the shafts will be longer accordingly. However, in the present invention, the rearward arrangement of the output shafts can be avoided by the frontal arrangement of the main shaft and the drive shaft. Is.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 6 are views for explaining a power transmission device for an engine for a motorcycle according to an embodiment of the present invention, wherein FIG. 1 shows a suspension support of the engine of the present embodiment on a vehicle body frame. 2 to 4 are a side view, a front view and a bottom view of the motorcycle, respectively.
Is a rear view of the vehicle body frame, and FIG. 6 is a bottom view of the rear arm.

In the figure, reference numeral 1 is an off-road motorcycle, and a head pipe 3 is welded to a front end of a body frame 2 of the motorcycle. A steering shaft of a front fork 4 is laterally attached to the head pipe 3. A front wheel 5 is rotatably supported, and a front wheel 5 is rotatably supported at the lower end of the front fork 4. A rear arm 6 is pivotally supported at the rear end of the body frame 2 so as to be vertically swingable, and a rear wheel 7 is pivotally supported at the rear end of the arm 6.

An engine unit 10 is suspended and supported on the vehicle body frame 2, a seat 11 is arranged above the engine unit 10, and a fuel tank 12 is arranged below the seat 11. . This fuel tank 1
The reference numeral 2 extends over the front and rear portions of the seat 11 to consider the concentration of the mass and optimize the capacity distribution. The seat 11 is surrounded by a side cover 13, and the vehicle body frame 2, the engine unit 10 and the front fork 4 are surrounded by uppers and lower cowlings 14a, 14b. At the bottom of the lower cowling 14b, there is formed a tool box storage portion (not shown).

The engine unit 10 is a water-cooled 4-cycle 5-valve L-type twin engine having an upper cylinder body 16a on the upper wall of the crankcase 15.
Cylinder head 17a, front cylinder body 1 on the front wall
6b and the cylinder head 17b are respectively fastened, and the head covers 18a and 18 are attached to the cylinder heads 17a and 17b, respectively.
It has a structure in which b is attached. The cylinders of the upper cylinder body 16a are oriented substantially vertically, and the cylinders of the lower cylinder body 16b are oriented substantially horizontally. Reference numeral 19 is a cam chain that rotationally drives the intake and exhaust valve cam shafts.

A rear cushion 20 is disposed in the rear portion of the crankcase 15 so as to be close to it, and the axial center of the cushion 20 is substantially parallel to the cylinder of the upper cylinder body 16a. An upper end 20a of the rear cushion 20 is pivotally supported by the support portion 2a of the vehicle body frame 2, and a lower end 20b thereof is pivotally supported by a link member 21 provided between the vehicle body frame 2 and the rear arm 6.

A generator 25 is provided on the left side of the crankcase 15, and a clutch mechanism 26 is provided on the right side. Also, both cylinder bodies 1
A starter motor 27 is provided between 6a and 16b, an oil tank 28 is provided in the body frame 2 above the starter motor 27, and a water pump 24 is provided below the lower cylinder body 16b. There is.

Intake ducts 29, 29 are connected to the cylinder heads 17a, 17b, respectively, and the axes of the ducts 29 are slightly deviated from the center line in the vehicle width direction to the left and right. A throttle body 29a is provided in the middle of both ducts 29, and a fuel injection injector (not shown) is arranged downstream of the throttle body 29a. The intake duct 29 is connected to an air cleaner 30 arranged at the front end of the vehicle body frame 2.
The air guide duct 30a extends to the front of the vehicle body and opens at the upper cowling 14a. A pair of elements 31 are arranged on the left and right inside the air cleaner 30, and the air guide duct 30 a communicates with a suction port at the upper end of the air cleaner 30. This improves water resistance and dust resistance.

Radiators 32a and 32b are arranged on the front left and right sides of the vehicle body frame 2, respectively, and a battery 33 is arranged below the right radiator 32a. An opening is formed in a portion of the upper cowling 14a that faces each of the radiators 32a and 32b, and ducts 32c and 32d are formed to introduce traveling wind from the opening to the radiators 32a and 32b. After the traveling wind passes through the radiator, the engine accessories and the like are cooled. The ducts 32c and 32d also function as mudguards.

An upper exhaust pipe 35 is connected to the rear surface of the upper cylinder head 17a, and a lower exhaust pipe 36 is connected to the lower surface of the lower cylinder head 17b. The upper exhaust pipe 35 once extends rearward from the cylinder head 17a, then bends to the front left side, and then extends around the outer periphery of the generator 25 and extends rearwardly of the lower part of the vehicle body.

The lower exhaust pipe 36 extends downward from the lower cylinder body 17 and then bends to the right side of the vehicle body, and then extends around the outer periphery of the engine to the left side portion of the vehicle body. And joins the upper exhaust pipe 35. The muffler 37 is connected to the merging portion 37a. By bending each of the exhaust pipes 35 and 36 in this manner, the required length of the exhaust pipe is secured, thereby improving the output in the low and medium speed range.

The body frame 2 is composed of the head pipe 3 and a pair of left and right main frames 41, 41 'extending from the head pipe 3 to the rear of the vehicle body. Both of the main frames 41, 41 'are wide plate-shaped members that cover the left and right sides of the engine unit 10,
The two frames 41, 41 'are formed substantially parallel to each other from the front portion to the rear end, and have a shape that connects the head pipe 3 and the pivot shaft 42 in a substantially straight line shape in a side view. Further, the interval between the two main frames 41, 41 'is set to a width slightly wider than the width of the engine unit 10, so that the engine unit 10 is sandwiched between the two frames 41, 41'.

The left main frame 41 has a two-part structure of an upper frame 41a and a lower frame 41b, and the two frames 41a and 41b are detachably connected with bolts. Also, this upper frame 41
An arc-shaped escape hole 41c is formed along the outer periphery of the generator 25 between a and the lower frame 41b. Further, triangular openings 41d are formed in the upper portions of the left and right main frames 41, 41 ', and the oil tank 28 is arranged so as to span the openings 41d.

A rear arm support bracket 42 is bolted and fixed to the outer surfaces of the rear end portions of the two main frames 41, 41 ', and the left and right pivot parts 40a of the rear arm 6 are mounted by the support bracket 42 via a pivot shaft 43. It is pivotally supported. The rear arm 6 has a generally H-shaped plan view in which the central portions of a pair of left and right arm bodies 40, 40 are connected to each other, and the pivot portion 40a is integrally formed at the front end of each arm body 40. . An axle 7a is inserted and fastened between the rear ends of the both arm main bodies 40,
The rear wheel 7 is pivotally supported on the axle 7a.

A pair of left and right rib portions 46 extending vertically along the rear cushion 20 are integrally formed inside the rear end portions of the main frames 41 and 41 '. The rear cushion 2 is provided between the upper ends of the ribs 46.
The support portion 2a that supports 0 is integrally formed, and thereby, the rigidity and the strength against the bound load are secured.
The lower ends of the ribs 46 are connected to each other by a connecting member 46a and a bolt 46b, and a bracket 46c formed on the connecting member 46a pivotally supports the front end 21a of the link member 21.

A crank shaft 50 is disposed in the crank case 15 in the vehicle width direction, and a crank pin 50a of the crank shaft is shared by both cylinders. Further, a speed change mechanism 51 is accommodated in the lower portion of the crankcase 15. The speed change mechanism 51 is formed by meshing a large number of speed change gears mounted on a main shaft 52 and a drive shaft 53, and the main shaft 52 and the drive shaft 53 are arranged in parallel with the crank shaft 50. Main shaft 52
The clutch mechanism 26 is attached to the right end of the.

The main shaft 52 of the speed change mechanism 51 is arranged below the crankshaft 50 and in front of the vehicle body, the drive shaft 53 is behind the main shaft 52 and in front of the crankshaft 50. It is arranged.

An output shaft 54 is arranged in parallel with the crankshaft 50 behind the drive shaft 53 in the crankcase 15, and the output shaft 54 is provided in the pivot shaft 4.
It is arranged on the same axis as 3.

Since the upper cylinder body 16a is substantially vertical and the output shaft 54 is located below the crankshaft and near the rear side thereof, the upper cylinder body 16a is Since the rear wall and the crankcase rear wall 15a are substantially flush with each other and perpendicular to each other, the rear cushion 20 can be brought closer to the engine unit 10 from this point without causing a dead space on the rear side of the engine.

An output gear (not shown) is coupled to the output shaft 54, and the output gear is the drive shaft 53.
Meshes with the drive gear of. The right end of the output shaft 54 projects from the case, and a drive sprocket 55 is connected to the projection. The output shaft 54 is coaxial with the pivot shaft 43 of the rear arm 60 described above.

The drive sprocket 55 and the driven sprocket 56 fixed to the rear wheel 7 are connected by a chain 57. The upper portion of the chain 57 shown in the drawing is disposed in a guide hole 40a formed through the arm body 40 'on the right side of the rear arm 6 in the front-rear direction. Further, chain guides 58, 59 for narrowing the chain 57 are meshed with the chain 57. The chain guides 58, 5
A rear arm 9 is rotatably supported by the rear arm 6, and its position in the direction perpendicular to the rear arm axis A can be adjusted. The chain guide 58 has the guide hole 4
It is arranged in 0a. The upper chain guide 58 is for adjusting the angle on the tension side of the chain during driving, and the lower chain guide 59 is for adjusting during engine braking.

The chain guide 58 or 59 has a rear arm axis A connecting the pivot shaft 43 and the axle 7a of the rear wheel 7 and an upper line B or a lower line C of the chain 57.
The angle θ formed by and can be adjusted to 0 degree or an angle slightly larger than this. Here, by adjusting θ to 0 degrees, the component force in the direction perpendicular to the rear arm axis A can be made zero, and by doing so, body pitching during actual running can be suppressed and maneuverability is improved. it can.

Next, the function and effect of this embodiment will be described. According to the motorcycle 1 of this embodiment, the main shaft 52 of the speed change mechanism 51 is arranged below the crankshaft 50 and in front of the vehicle body, and the drive shaft 53 is arranged behind the main shaft 52 and in front of the crankshaft 50. Therefore, the length of the entire engine unit 10 in the front-rear direction can be shortened,
As a result, the engine weight can be concentrated on the center of gravity of the vehicle, and the moment of inertia around the center of gravity can be reduced.

Since the entire engine can be made compact, it is possible to improve the degree of freedom in the vehicle body mounting positions of the engine, engine accessories, rear cushion, etc., and to improve maneuverability and running performance. That is, heavy objects such as the rear cushion 20 and the fuel tank 12 can be concentrated on the center of gravity of the vehicle, and the moment of inertia can be reduced also from this point.

Further, in this embodiment, since the main shaft 52 and the drive shaft 53 are arranged in front of the crank shaft 50, the axial distance between the front and rear wheels 5, 7 can be shortened by that much, and the maneuverability can be improved. Here, when the distance between the shafts is the same, the rear arm 6 can be lengthened, so that the behavior can be stabilized by the amount that the swing angle can be reduced.

Further, in this embodiment, the engine output shaft 54
Since the pivot shaft 43 of the rear arm 6 and the pivot shaft 43 of the rear arm 6 are arranged coaxially, it is possible to suppress the tension fluctuation of the chain 57 due to the vertical movement of the rear wheel 7 and to suppress the increase in the axial distance. Further, in this case, since the upper cylinder body 16a is arranged substantially vertically and the output shaft is arranged in the vicinity of the rear side of the crankshaft, the rear wall of the crankcase becomes substantially flush and substantially vertical, and the cushion unit 20 becomes a more engine unit. Since they can be brought close to each other, the heavy object can be brought closer to the center of gravity of the vehicle, and the moment of inertia around the center of gravity can be reduced.

Further, in this embodiment, both main frames 4 are
Since 1, 41 'covers the left and right sides of the engine unit 10, it is possible to secure a sufficient width in the vertical direction.
The vertical rigidity against drop strength can be improved while improving the torsional rigidity and lateral rigidity. Also, both main frames 41, 4
Since the dimension between 1'is made narrow and parallel, the torsion moment around the head pipe can be made small, and the rigidity can be improved also from this point.

Further, since the space between the main frames 41 and 41 'is narrowed, the engine accessories such as the seat 11, the fuel tank 12 or the radiator 32 can be slimmed down accordingly, and the whole vehicle body can be slimmed down. The maneuverability can be improved.

[0040]

As described above, according to the power transmission device for a motorcycle engine of the first aspect of the present invention, the main shaft constituting the speed change mechanism is arranged below the crankshaft and in front of the vehicle body. Can be made compact, the moment of inertia around the center of gravity can be reduced, the degree of freedom of the vehicle body mounting position can be improved, and the maneuverability can be improved by the amount that the axial distance can be shortened.

According to the second aspect of the present invention, the drive shaft is arranged rearward of the main shaft with respect to the vehicle body and forward of the crankshaft with respect to the vehicle body. Therefore, the length in the front-rear direction of the engine can be further reduced, which contributes to further compactness.

According to the third aspect of the invention, since the output shaft and the pivot shaft of the rear arm are coaxially arranged, the tension of the chain or the like caused by the vertical movement of the rear wheel is avoided while avoiding a long distance between the shafts. It has the effect of suppressing fluctuations.

[Brief description of drawings]

FIG. 1 is a side view for explaining a power transmission device for a motorcycle engine according to an embodiment of the present invention.

FIG. 2 is a side view of a motorcycle equipped with the engine of the embodiment.

FIG. 3 is a front view of the motorcycle of the above embodiment.

FIG. 4 is a bottom view of the engine of the embodiment.

FIG. 5 is a rear view of the vehicle body frame of the above embodiment.

FIG. 6 is a bottom view of the rear arm of the above embodiment.

FIG. 7 is a right side view of the vehicle body frame of the above embodiment.

FIG. 8 is a left side view of the vehicle body frame of the above embodiment.

[Explanation of symbols]

 1 Motorcycle 6 Rear Arm 7 Rear Wheel 10 Engine Unit 43 Pivot Shaft 50 Crank Shaft 51 Transmission Mechanism 52 Main Shaft 53 Drive Shaft 55 Drive Sprocket

Claims (3)

[Claims] 1. A motorcycle in which a main shaft and a drive shaft constituting a speed change mechanism are arranged in parallel with a crankshaft, and rotation of the crankshaft is transmitted from the main shaft to the rear wheels via the drive shaft. A power transmission device for an engine of a motorcycle, wherein the main shaft is arranged below a crankshaft and in front of a vehicle body. 2. The power transmission device for a motorcycle engine according to claim 1, wherein the drive shaft is disposed rearward of the main shaft with respect to the vehicle body and forward of the crankshaft with respect to the vehicle body. 3. The output shaft having a drive sprocket for transmitting power from the drive shaft to a rear wheel according to claim 1 or 2, the output shaft and the pivot shaft of the rear arm being arranged in parallel with the crank shaft. A power transmission device for a motorcycle engine, characterized in that and are coaxial.