JP2001001978A - Power unit for motorcycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact power unit for a motorcycle allowing a large bank angle of a vehicle body. SOLUTION: A power unit for a motorcycle is placed at a lower part of a vehicle body. An axial line C1 of a crankshaft 31 direction in a longitudinal direction of the body is placed close to a body center C0. A cylinder 45 is placed such that an axial line C2 of the cylinder 45 tilts in a right upward direction in respect to the axial line C1 of the crankshaft 31. A power transmission 90 is placed such that an axial line C5 of a center shaft 93 of a transmission is directed in the longitudinal direction of the body at a left upward part in respect to the axial line C1 of the crankshaft 31. A front end of the center shaft 93 of the transmission is placed forward of a rear end of the crankshaft 31.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a power unit mounted on a motorcycle, and more particularly, to an arrangement structure of an internal combustion engine and a power transmission device constituting a power unit disposed below a vehicle body.

[0002]

2. Description of the Related Art A known motorcycle has a power unit disposed below a step floor of a vehicle body in order to lower the center of gravity of the vehicle body (Japanese Patent Laid-Open No. 60-9 / 1985).
No. 2929).

In this motorcycle power unit, the crankshaft of a single-cylinder internal combustion engine is arranged vertically with its axis oriented in the front-rear direction of the vehicle body, and the cylinder of the internal combustion engine is arranged horizontally in the left-right direction of the vehicle body. Extending. Also,
The output shaft of a transmission such as a clutch or a speed reducer that transmits the power of the internal combustion engine to the rear wheels is arranged coaxially with the crankshaft.

[0004]

In the conventional power unit for a motorcycle, a cylinder head is provided on the lower side of the vehicle body to the right with a width substantially equal to the center of the vehicle body in the left-right direction, and to the right and the left. The transmission case is
Each of them has a shape that protrudes horizontally, so that the bank angle of the vehicle body is restricted, and there is a problem that the bank angle cannot be made large. In addition, since the crankshaft and the output shaft of the transmission are coaxial, the power unit has been elongated in the front-rear direction of the vehicle body.

The present invention has been made in view of such circumstances, and has as its object to provide a compact power unit for a motorcycle that can increase the bank angle of a vehicle body. I do.

[0006]

The invention according to claim 1 of the present application is directed to an internal combustion engine having a crankshaft having an axis oriented in the front-rear direction of a vehicle body, and the power of the crankshaft being transmitted to a rear wheel. A power transmission device for transmitting power to the vehicle, and a power unit of the motorcycle disposed below the vehicle body, wherein the axis of the crankshaft is disposed near the center of the vehicle body, and the cylinder of the internal combustion engine is Is arranged so as to incline upward in one of left and right directions of the vehicle body with respect to the axis of the crankshaft, and the power transmission device is provided with a transmission provided in the power transmission device. The axis of the central axis is arranged so as to be directed in the front-rear direction of the vehicle body in the other left-right direction of the vehicle body and obliquely upward with respect to the axis of the crankshaft. Front end, a power unit of the motorcycle is positioned in front of the rear end of the crankshaft.

According to the first aspect of the present invention, the axis of the cylinder is oriented in one of the left and right directions with respect to the axis of the crankshaft which is oriented in the front-rear direction of the vehicle body and located near the center of the vehicle body. Since it is inclined upward and the axis of the central axis of the transmission of the power transmission device is disposed obliquely upward and in the front-rear direction in the other direction in the left-right direction, one direction in the left-right direction with respect to the vehicle body center. In the motorcycle in which the power transmission device is disposed obliquely upward in the other direction and the power transmission device is disposed obliquely upward in the other direction, the power unit is disposed below the vehicle body to lower the center of gravity of the vehicle. Thus, the bank angle of the vehicle body can be increased.

In addition, since the front end of the center shaft of the transmission of the power transmission device is located forward of the vehicle body with respect to the rear end of the crankshaft, the length of the power unit in the front-rear direction can be reduced, and the power transmission can be made compact. It can be a power unit.

According to a second aspect of the present invention, in the motorcycle power unit according to the first aspect, an axle of the rear wheel is driven via a shaft drive mechanism of the power transmission device, and an axis of the crankshaft. Is disposed below the axis of the drive shaft of the shaft drive mechanism.

According to the second aspect of the invention, since the axis of the crankshaft is disposed below the axis of the drive shaft, the required height of the drive shaft for driving the axle on which the rear wheels are mounted is ensured. Then, the center of gravity of the power unit can be reduced, and thus the center of gravity of the vehicle body can be reduced.

In this specification, "front, rear, left and right"
Means front, rear, left and right in the vehicle body. The “center of the vehicle body” means a vertical plane passing through a center position in the left-right direction of a wheel mounted on the motorcycle. Further, “near the center of the vehicle body” means within the range of the width of the wheels mounted on the motorcycle in the left-right direction.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 3 are views for explaining the first embodiment, and FIG. 1 is a left side view of a scooter type motorcycle 1 on which a power unit 7 of the present invention is mounted. The motorcycle 1 has a bolt 2
And a main frame composed of a front frame 3 and a rear frame 4 connected by a frame. A front suspension mechanism for suspending the front wheels 5 and a steering mechanism for steering the front wheels 5 are provided at a front portion of the front frame 3, and a power unit 7 for driving rear wheels 6 is provided behind and in front of the rear frame 4. A rear suspension mechanism for suspending a rear wheel 6 is provided at a rear portion of the rear frame 4, and a seat 8 is provided above the rear frame 4.

A front fender 9, a front cover 10, a step floor 11, a frame body cover 12, and a rear fender 13 are attached to the motorcycle 1 in order from the front to the rear.
1 is provided with a pair of left and right side covers 13.
Inside the frame body cover 12 below the seat 8, a storage box 15 for storing a helmet or the like is provided.

The front suspension mechanism includes a swing arm 1 located on the right side of the front wheel 5 and supported by a support shaft at the front lower end of the front frame 3 so as to be vertically swingable.
6 and a shock absorber 17 having one end pivotally attached to the swing arm 16 and the other end pivotally attached to the front frame 3. An axle holder 19 is attached to the front end of the swing arm 16 via a king pin 18 so as to be swingable in the left-right direction, and the front wheel 5 is rotatably supported by an axle 20 attached to the axle holder 19. .

The steering mechanism includes a front frame 3
A handle post 22 rotatably supported by a head pipe 21 attached to a front upper end of the steering wheel, and a steering arm 2 attached to a lower end of the handle post 22
3 and a link 24 pivotally connected at one end to a steering arm 23 and at the other end to an arm 19 a of the axle holder 19. In this way, the steering mechanism and the front suspension mechanism are mutually independent mechanisms to improve the maneuverability.

A front portion of the power unit 7 is provided with brackets 25 respectively attached to a pair of right and left rear frames 4.
And bushings 46 provided at the front end of a lower crankcase 42 of the internal combustion engine 30 and the front end of a cylinder head 43 (see FIG. 2).
And, with a pair of hanger bolts inserted respectively,
It is swingably supported by the rear frame 4. On the other hand, a rear portion of the power unit 7 is attached to a rear portion of the left rear frame 4 via a shock absorber 27. This allows the power unit 7 to swing up and down in accordance with the ups and downs of the road surface during traveling.

In order to lower the center of gravity of the vehicle body, the power unit 7 is disposed below the vehicle body. As an example of the arrangement, the axes of the two pipe bushes 46 are located slightly above the horizontal plane including the axis C1 of the crankshaft 31 of the internal combustion engine 30, and the two axes of the two pipe bushes 46 are positioned above the upper surface of the step floor 11. And the upper end surface of the power unit 7 excluding the radiator 41 has a height substantially equal to the extension surface of the upper surface of the step floor 11.

The power unit 7 includes an internal combustion engine 30 and a power transmission device 90 including a planetary gear type transmission 91 and a final reduction gear 110. The internal combustion engine 30 is a spark-ignition, four-cycle, single-cylinder, water-cooled internal combustion engine. A flexible air introduction pipe 33 extending from an air cleaner 32 disposed below the frame body cover 12 is disposed on the right side of the vehicle body. It is connected to the upstream end of the throttle body 34. An intake pipe 35 connected to an intake port of a cylinder head 43 is connected to a downstream end of the throttle body 34, and a fuel injection valve 36 is attached to the intake pipe 35. Fuel is supplied to the fuel injection valve 36 from a fuel tank 37 arranged below the step floor 11. On the right side of the vehicle body, an exhaust muffler 39 connected to an exhaust pipe 38 connected to an exhaust port of the cylinder head 43 is arranged. Further, a radiator 41 to which cooling air from a cooling fan disposed in a fan cover 40 attached to a front end of the crankcase 42 is applied is disposed above the crankcase 42.

The output of the transmission 91 of the power transmission device 90 is
The power is transmitted to the axle of the rear wheel 6 by a shaft drive mechanism having a drive shaft 111 of the final reduction gear 110, and the rear wheel 6 is driven.

Next, FIG. 2 is a schematic view of a main portion focusing on meshing of gears when the crankcase 42 and the cylinder head 43 are cut along the line II-II in FIG. 1 and the line III-III in FIG. Referring to FIG. 3 which is a sectional view,
The power unit 7 will be further described.

The internal combustion engine 30 is constructed by sequentially assembling a crankcase 42, a cylinder head 43, and a cylinder head cover 44 and assembling them. The crankcase 42 is connected to the axis C of the crankshaft 31 of the internal combustion engine 30.
1 and is divided into upper and lower crankcases 42U and 42L by a split surface A inclined with respect to the horizontal plane. The split surface A in the lower crankcase 42L is
It is directed to the upper right of the vehicle body. A cylinder 4 having an axis C2 inclined upward and to the right of the vehicle body with respect to the axis C1 of the crankshaft 31 is provided above the upper crankcase 42U.
The cylinder head 43 is mounted on the mounting surface B of the cylinder head 43 on the mounting surface B facing the upper right of the cylinder 45.

Also, both crankcases 42U, 42L
Is also a part of the transmission case that covers the front part of the transmission 91 of the power transmission device 90 that transmits the power of the crankshaft 31 to the rear wheels 6. Further, a tube bush 46 through which a hanger bolt for supporting the power unit 7 is inserted into the bracket 25 of the rear frame 4 is provided on the outer surface of the front end of the lower crankcase 42L. This tube bush 46
Cylindrical portion 46a integrally formed with lower crankcase 42
And an elastic member 46b made of a cylindrical rubber or the like whose outer peripheral surface is fixed to the inner peripheral surface of the cylindrical portion 46a, and an outer peripheral surface fixed to the inner peripheral surface of the elastic member 46b and a hanger bolt is inserted inside. And a metal insertion tube 46c. Further, a tube bush 46 having the same structure is also provided on the cylinder head 43.

The crankshaft 31 is so-called vertically disposed with its axis C1 pointing in the front-rear direction of the vehicle body, and is supported by the crankcase 42 via a pair of main bearings 49 and 50. Each of the main bearings 49 and 50 is held in a semi-cylindrical concave groove formed on the split surface A of each of the crankcases 42U and 42L.
1 is located on the split plane A. The position in the left-right direction of the axis C1 of the crankshaft 31 is on the left side of the vehicle body center C0 and near the vehicle body center C0, but the position is the maximum bank angle of the vehicle body in the right direction and the left direction. Are set appropriately in the vicinity of the vehicle body center C0 such that are substantially equal to each other.

A connecting rod 48 having a small end pivotally connected to a piston pin of a piston 47 slidably fitted in a cylinder bore of the cylinder 45 and a large end pivotally connected to a crankpin of the crankshaft 31 is provided. Thus, the crankshaft 31 is driven to rotate by the reciprocating piston 47. The crankshaft 31 is provided with a balance weight 31a on the opposite side of the piston pin to suppress the generation of vibration due to the reciprocating motion of the piston 47 and the connecting rod 48.

Here, the relationship between the split surface A, the mounting surface B, and the axis C2 of the cylinder 45 will be described in more detail. The cylinder 4 is orthogonal to the axis C1 of the crankshaft 31 and
5, a reference vertical line which is a vertical half line extending upward from an intersection between the split plane A and the reference plane and an intersection between the axis C1 of the crankshaft 31 and the reference plane. Is an acute angle. The angle β between the axis C2 of the cylinder 45 and the reference vertical line is also acute, and the angles α and β are substantially equal. Further, an angle γ, which is an angle formed by an extension of an intersection of the mounting surface B and the reference plane and the reference vertical line and is an isotope of the angle α, is smaller than the angle α. Therefore, an intersection line between the split plane A and the reference plane, an intersection line between the mounting surface B and the reference plane, and an axis C2 of the cylinder 45 are formed between the intersection line between the vehicle center C0 and the reference plane. The angles are also an angle α, an angle β, and an angle γ, respectively. The values of these angles α, β, γ are
It is appropriately set in consideration of the size of the bank angle to be set and the like.

As a result, with respect to the split surface A and the mounting surface B which are inclined from the lower right to the upper left, the mounting surface B is inclined at a larger angle with respect to the horizontal plane than the split surface A. The plane including the split plane A and the plane including the mounting plane B intersect below the cylinder 45.

The cylinder head 43 has a double-acting piston-type supercharger 52 in addition to an intake port and an exhaust port.
Are formed, and each port communicates with a combustion chamber formed on the lower surface of the cylinder head 43. A mixture of fuel and air injected from the fuel injection valve 36 toward the intake port is supplied to the combustion chamber. An ignition plug 51 for igniting the air-fuel mixture is attached to the cylinder head 43 facing the combustion chamber.

In the rear ends of the cylinder head 43 and the upper crankcase 42, holes formed by semi-cylindrical concave grooves formed on the mounting surface B of the upper crankcase 42 and the cylinder head 43, respectively. And a supercharging cylinder 52a forming a housing of the supercharger 52 is fitted in the hole.

Further, the cylinder head 43 and the upper crankcase 42U are provided with a camshaft 53 whose axis C3 is oriented in the front-rear direction of the vehicle body.
It is rotatably supported via 55. Each bearing 54,
55 is the upper crankcase 42 and the cylinder head 4
3 are held in semi-cylindrical concave grooves formed on the mounting surface B, respectively, so that the axis C3 of the cam shaft 53 is positioned on the mounting surface B. With such an arrangement of the cam shaft 53, the height of the cylinder 45 in the axial direction can be suppressed lower than that of an internal combustion engine in which the cam shaft is supported only by the cylinder head, and the overhang dimension of the power unit 7 in the left-right direction can be reduced. can do.

As shown in FIG. 3, the crankshaft 31
An AC generator 56 is provided at a front end located forward of the main bearing 49 on the front side, and a rotor 56 a of the generator 56 is fixed to the crankshaft 31 by a nut 57 at the front end of the crankshaft 31. Have been. Further, a cooling fan 58 for sending cooling air to the radiator 41 is attached to the rotor 56 a of the generator 56 by bolts 59.

On the other hand, the main bearing 50 on the rear side of the crankshaft 31
Further rearward, a first drive gear 60 and a second drive gear 61 are respectively attached so as to rotate integrally with the crankshaft 31 in order toward the rear. A fitting hole coaxial with the crankshaft 31 is formed in the rear end face of the crankshaft 31, and a drive shaft 62 a of a hollow oil pump 62 is fitted in the fitting hole, and is integrally formed with the crankshaft 31. It is designed to rotate. The oil pump 62 is of a troykoid type, and includes two crankcases 42U, 42U.
The rotor 62b is rotationally driven by the drive shaft 62a within the internal space of the casing formed by using the L and the joint surface with the transmission case 92.

The oil stored at the bottom of the lower crankcase 42 is supplied to an intake passage 63 formed in the transmission case 92.
Is sucked into the oil pump 62 through the
Is supplied to the camshaft 53, the center shaft 93 of the transmission 91, and the bearings through oil passages and oil pipes provided in the crankcase 42 and the transmission case 92, respectively. Further, the two main bearings 49 of the crankshaft 31,
Discharged oil is supplied to the sliding portion 50 and the sliding portion between the crankpin 31b and the large end of the connecting rod through the inside of the drive shaft 62a.

The first drive gear 60 meshes with a large gear 65 mounted so as to rotate integrally with the idler shaft 64. Since the idler shaft 64 also serves as a balancer shaft as described later, the number of teeth of the large gear 65 is set equal to the number of teeth of the first drive gear 60 so that the idler shaft 64 rotates at the same rotation speed as the crankshaft 31. In order to rotate the cam shaft 53, a small gear 66 meshing with a cam gear 67 provided so as to rotate integrally with the cam shaft 53 includes a large gear 65.
Are provided integrally. The camshaft 53 rotates once every two rotations of the crankshaft 31 by the series of gear trains 60, 65, 66, and 67.

The cam gear 67 is spline-connected to a supercharging crankshaft 52c for reciprocating a supercharging piston 52b of a double-acting piston type supercharger 52. The camshaft 53 has a hollow portion serving as an oil passage for supplying oil to a sliding portion between each cam and each rocker arm, which will be described later. The hollow portion has an end on the supercharger 52 side. Supercharged crankshaft 52
The extension of c is press-fitted. Thereby, the camshaft 5
3 rotates integrally with the supercharged crankshaft 52c.

The camshaft 53 is provided with an intake cam, an exhaust valve (not shown), and an intake cam, an exhaust cam, and a supercharge cam for driving the supercharge valve 69 to open. The intake valve 68 includes a rod 72 which is pulled down by an intake first rocker arm 70 which swings in contact with an intake cam.
The valve is driven to be opened by the intake second rocker arm 71 which is swung by. Like the intake valve 68, the exhaust valve is also driven to open by an exhaust second rocker arm that is swung by a rod that is lowered by an exhaust first rocker arm that is swung by contacting an exhaust cam. On the other hand, the supercharging valve 69 is a supercharging second rocker arm 7 that is oscillated by a rod 75 pushed up by a supercharging first rocker arm 73 that is oscillated in contact with a supercharging cam.
4, the valve is driven to open.

In order to control the internal combustion engine 30, a rotation position sensor 76 for detecting the rotation position of the cam shaft 53 is attached to the cylinder head 43 by a rotation plate fixed to the front end of the cam shaft 53. The sensor 76 detects an engine stroke state required for fuel injection timing control.

The idler shaft 64 whose axis C4 is oriented in the front-rear direction of the vehicle body is formed in a cylindrical shape, and has a large cylindrical portion 64a and a small cylindrical portion 64b. The large cylindrical portion 64a and the small cylindrical portion 64b are rotatably supported by a pair of bearings 77, 78 held by both crankcases 42U, 42L. Each of the bearings 77 and 78 is a main bearing 4 of the crankshaft 31.
As in the cases 9 and 50, the crankcases are held in semi-cylindrical concave grooves formed on the split surfaces A of the two crankcases 42U and 42L so that the axis C4 of the idler shaft 64 is positioned on the split surface A. Has been. Further, since the split surface A is inclined at an angle α with respect to the vehicle body center C0, the idler shaft 6
The axis C4 of No. 4 is located below the axis C1 of the crankshaft 31 and on the right side with respect to the center C0 of the vehicle body.

The housing 79a of the cooling water pump 79 is housed inside the large cylindrical portion 64a with a radial gap from the inner peripheral surface of the large cylindrical portion 64a. A cover 79b of the cooling water pump 79 is attached to the housing 79a in a liquid-tight manner, and a water pipe 80 from an outlet tank of the radiator 41 is connected to the cover 79b. Further, the cylinder 45 has a discharge hole 81 (see FIG. 2) communicating with the discharge part of the cooling water pump 79 and communicating with a cooling water jacket formed around the cylinder bore.

In the pump chamber formed by the housing 79a and the cover 79b, there is a rotatable shaft that extends in the pump chamber in the axial direction and has one end rotatably supported by the top of the cover 79b and the other end rotatably by the bottom of the housing 79a. Axis 7
9c is provided. The cooling water pump 79 has an impeller 79d that has three blades and is integrally attached to a rotating shaft 79c, and a permanent magnet 79e is attached to the shaft of the impeller 79d in the circumferential direction. The inner peripheral surface of the large cylindrical portion 64a of the idler shaft 64 and the housing 79
a permanent magnet 79f is attached to the inner peripheral surface of the large cylindrical portion 64a in the circumferential direction with a small gap between the large cylindrical portion 64a and the housing 79a. A magnetic coupling is formed with the permanent magnet 79e.

The radiator 41 is disposed between the V-shape formed by the upper crankcase 42U and the cylinder head 43.
2 and the cylinder head 43 respectively.

Therefore, when the idler shaft 64 rotates, the impeller 79d rotates via this magnetic coupling, and the cooling water flowing into the pump chamber through the water pipe 80 is
The pressure is made high by the impeller 79d, and the pressure is sent to the cooling water jacket through the discharge hole 81.

As shown in FIG. 2, the cooling water having cooled the high-temperature portions of the cylinder 45 and the cylinder head 43 flows from the cooling water outlet of the cylinder head 43 to the inlet side tank of the radiator 41 via the thermostat 82. Inflow. The cooling water outlet of the cylinder head 43 is formed in a protruding cylindrical shape, and the protruding cylindrical portion penetrates through the chamber wall of the housing chamber 41a formed on the side of the inlet-side tank of the radiator 41, and the housing chamber 41a , Fluid communication between the cooling water outlet of the cylinder head 43 and the inlet-side tank of the radiator 41 is achieved. Thermostat 82
Is disposed and attached in a flow path at a portion where the protruding cylindrical portion penetrates the chamber wall of the storage chamber 41a.

As described above, the radiator 41 can be compactly arranged in the V-shaped space formed by the upper crankcase 42U and the cylinder head 43, and the power unit 7 can be made more compact. Become. In addition, the need for piping of a water pipe such as a hose connecting the cooling water outlet of the cylinder head 43 and the inlet side tank of the radiator 41 is eliminated, and the degree of freedom in arranging peripheral components can be increased. Further, the communication connection of the cooling water passage is extremely easy.

Further, the large cylindrical portion 64a of the idler shaft 64
A cylindrical weight 83 having an opening in a part thereof is attached to the outer peripheral surface of the balance weight 31a.
Vibration generated by the rotation of the crankshaft 31 provided with
A balancer for suppressing the vibration generated by the reciprocating motion of the piston 47 and the connecting rod 48 is formed.

Accordingly, the idler shaft 64 is a drive shaft for driving the cooling water pump 79, and is also a balancer shaft as described above. Thus, the cam shaft 53
The idler shaft 64 provided in the driving mechanism for driving the cooling water pump 7 is a coaxial two-axis type rotating shaft.
9 as a drive shaft and a balancer shaft. As a result, costs can be reduced as compared with the case where a rotating shaft having these functions is provided separately from the idler shaft.

The cam shaft 53 and the idler shaft 6
4 is located on the side where the plane including the split surface A and the plane including the mounting surface B intersect with each other with respect to the axis C2 of the cylinder 45, that is, on the side where the split surface and the mounting surface approach each other. The idler shaft 64 supported on the surface A and the cam shaft 53 supported on the mounting surface B can be arranged close to each other, and another intermediate shaft is interposed between the idler shaft 64 and the cam shaft 53. Without directing the two, the small gear 6
6 and the cam gear 67. Therefore, the height of the cylinder 45 in the direction of the axis C2 can be kept low, and the size of the power unit 7 extending in the left-right direction is reduced, so that the power unit 7 is compact. Also, the number of parts can be reduced because the intermediate shaft is not required.

The cam shaft 53 and the idler shaft 64
Is a cylinder 45 inclined upward and to the right from the crankshaft 31.
, The center of gravity of the power unit 7 can be lowered.

Further, an idler shaft 64, which is a coaxial biaxial rotary shaft having a plurality of functions, is provided in a narrow space between the split surface A and the mounting surface B on the intersecting side of the cylinder 45. Are arranged in a concentrated manner, a wide space without a rotation axis can be formed on the side surface of the cylinder 45 on the opposite side, and peripheral components can be arranged in the space.

On the other hand, a planetary gear type transmission 91 which is a component of the power transmission device 90 has a center shaft 93 and an input gear 9.
4, a start clutch 95, second speed shift clutches 96, 97, 98 for second speed, third speed and fourth speed, and an output shaft 99. A center shaft 93 oriented in the front-rear direction of the vehicle body is the center shaft of the transmission 91, and its front end is located on the split surface A of the upper and lower crankcases 42U and 42L. , 42L are respectively fitted into bottomed semi-cylindrical concave grooves formed on the inner surfaces of the front end portions, and the rear end portions of the concave portions are formed on the case of the final reduction gear transmission 110 mounted on the rear end surface of the transmission case 92. It is inserted and supported in the support hole. The center shaft 93 cannot be rotated by the detent member 100 covering the shaft end attached to the case of the final reduction gear 110.

Therefore, the axis C5 of the center shaft 93 is
It is located on the split plane A and extends in the front-rear direction of the vehicle body diagonally above and to the left with respect to the axis C1 of the crankshaft 31 disposed near the vehicle body center C0. As a result, the power transmission device 90 is also disposed obliquely to the upper left with respect to the axis C1 of the crankshaft 31.

On the other hand, the axis C4 of the idler shaft 64, which is also supported on the split surface A, extends obliquely right below the axis C1 of the crankshaft 31 in the front-rear direction of the vehicle body. As a result, the center shaft 93 and the idler shaft 64 of the transmission 91 are disposed on both sides of the crankshaft 31 with respect to the crankshaft 31, as compared with the case where two rotating shafts are disposed on only one side of the crankshaft 31. In addition, the overhang dimension of the power unit 7 in the left-right direction can be reduced, and the power unit 7 can be made compact.

Since the front end of the center shaft 93 is supported by the front ends of the two crankcases 42U and 42L, the front end of the center shaft 93 is located forward of the rear end of the crankshaft 31 in the vehicle body. positioned. Therefore, since the crankshaft 31 and the center shaft 93 can be arranged so as to overlap in the front-rear direction, the length of the power unit 7 in the front-rear direction can be shortened, and the power unit 7 can be made compact.

Hereinafter, the operation of the transmission 91 will be mainly described. The second drive gear 61 of the crankshaft 31 is
3 is engaged with an input gear 94 attached to a flange provided at a central portion in the axial direction of a flanged boss 101 rotatable. The rear part of the flanged boss 101 is coupled so as to rotate integrally with the clutch inner 95a of the starting clutch 95, and the front part engages with a small gear 104 of an idler shaft constituting a speed reduction mechanism of a starter motor. Starting driven gear 105 is one-way clutch 10
6 is attached. At the time of starting, the rotation of the starting motor is cranked through the pinion 102, the large idler shaft gear 103, the small idler shaft gear 104, the starting driven gear 105, the one-way clutch 106, the input gear 94, and the second drive gear 61. It is transmitted to the shaft 31.

The starting clutch 95 is provided coaxially with the center shaft 93, and includes a clutch inner 95 a and an outer clutch 9.
5b and a centrifugal weight 95c, and when the clutch inner 95a reaches a predetermined rotational speed, the centrifugal weight 9c
By the operation of 5c, the clutch inner 95a and the outer clutch 95b are connected and rotate together, so that the starting clutch 95 is in a completely connected state.

Each of the speed change clutches 96, 97, 98
Has a planetary gear mechanism and a clutch mechanism. The clutch outer of the clutch mechanism is integrally connected to the internal gear of the planetary gear mechanism, and the clutch inner of the clutch mechanism is integrally connected to the carrier that supports the planetary gear of the planetary gear mechanism. Further, the carrier has a centrifugal weight that integrates the clutch outer and the clutch inner via a plurality of clutch plates when the rotation speed reaches a predetermined rotation speed. The sun gear is mounted on the center shaft 93 via a one-way clutch.

The clutch outer 95b of the starting clutch 95
Are integrally connected to the clutch outer 96a of the second speed transmission clutch 96, and are connected to the carrier 9 of the second speed transmission clutch 96.
6b is a clutch outer 97 of the third-speed transmission clutch 97
a. Similarly, the carrier of the third speed transmission clutch 97 is integrally connected to the clutch outer of the fourth speed transmission clutch 98, and the carrier of the fourth speed transmission clutch 98 is integrally connected to the output shaft 99.

In the second-speed transmission clutch 96, the one-way clutch 96 is operated until the clutch mechanism operates to reach a predetermined rotation speed at which the internal gear, which is also the clutch outer 96a, and the carrier 96b, which is also the clutch inner, are integrated.
Due to the sun gear 96c that does not rotate due to d, the carrier 96b rotates at a predetermined reduction ratio, and 3
The clutch outer 97a of the speed change clutch 97 rotates. Similarly, the clutch outer of the fourth-speed transmission clutch 98 is rotated at a predetermined reduction ratio by the deceleration operation of the third-speed transmission clutch 97, and the output shaft is output at a predetermined reduction ratio by the deceleration operation of the fourth-speed transmission clutch 98. By rotating 99, a maximum reduction ratio is obtained.

Next, in the second speed transmission clutch 96, when the rotation speed of the carrier 96b reaches a predetermined rotation speed and the clutch mechanism is operated to integrate the internal gear and the carrier 96b, the second speed transmission clutch 96 The entire body rotates together without deceleration, and the carrier rotates at a predetermined reduction ratio until the carrier of the third-speed transmission clutch 97 reaches a predetermined number of rotations. The clutch outer of the clutch 98 rotates. Further, the output shaft 99 is rotated at a predetermined reduction ratio by the deceleration action of the fourth speed transmission clutch 98, so that a smaller reduction ratio can be obtained.

Similarly, when the third-speed transmission clutch 97 rotates integrally without deceleration by the operation of the clutch mechanism, the output shaft is driven at a predetermined reduction ratio by the deceleration operation of the fourth-speed transmission clutch 98. 99 is rotated to obtain a smaller reduction ratio. And the fourth-speed transmission clutch 9
When the clutch mechanism 9 operates integrally and rotates as a whole without deceleration, the clutch inner 95a of the starting clutch 95 and the output shaft 99 are directly connected,
The output shaft 99 is rotated at the same rotational speed as the clutch inner 95a.

The predetermined rotational speeds have different values, and are appropriately set in consideration of the speed change characteristics.

The output of the transmission 91 operating in this manner is:
The power is transmitted to the rear wheel 6 by the shaft drive mechanism. That is, the output gear 107 attached to the output shaft 99 of the transmission 91 meshes with the gear 112 fixed to the drive shaft 111 of the final reduction gear transmission 110. The position is closer to the vehicle center C0 than the center axis 93, and its axis C
6 is a drive shaft 1 arranged in the front-rear direction of the vehicle body
In FIG. 11, a bevel gear (not shown) is formed at the rear end of the bevel gear, and this bevel gear meshes with a driven bevel gear attached to the axle of the rear wheel 6. Thus, the rotation of the output shaft 99 is reduced, and the rear wheel 6 is driven. At this time, the axis C1 of the crankshaft 31 is located below the axis C6 of the drive shaft 111 set according to the size of the wheels, so that the center of gravity of the power unit 7 is reduced, and thus the center of gravity of the vehicle body is reduced. (See FIG. 1).

For controlling the internal combustion engine 30, a speed sensor 113 for detecting a rotation signal of the drive shaft 111 is attached to the case of the final reduction gear 110. The rotation speed of the output shaft 99 is detected.

This embodiment has the following effects because it is configured as described above. Crankshaft 31 oriented in the front-rear direction of the vehicle body and arranged near vehicle body center C0
The axis C2 of the cylinder 45 inclines to the upper right with respect to the axis C1, and the axis C5 of the center shaft 93 of the planetary gear type transmission 91, which is a component of the power transmission device 90, is directed obliquely to the upper left. With respect to the vehicle body center C0, the cylinder 45
Are arranged at the upper left and inclined at substantially the same angle.
As a result, in the motorcycle 1 in which the power unit 7 is disposed below the vehicle body for lowering the center of gravity of the vehicle body, it is possible to increase the bank angle of the vehicle body. In addition, the right and left sides can be balanced because they are inclined at substantially the same angle.

The front end of the center shaft 93 of the planetary gear type transmission 91 is located on the inner surface of the front ends of the two crankcases 42, which is the position forward of the vehicle body from the rear end of the crankshaft 31. Can be shortened in the front-rear direction, and a compact power unit 7 can be obtained.

The axis C1 of the crankshaft 31 is the drive shaft 1
11 is disposed below the axis C6 of the drive shaft 11, the required height of the drive shaft 111 for driving the axle on which the rear wheel 6 is mounted is ensured, and the center of gravity of the power unit 7 is reduced, and hence the center of gravity of the vehicle body is reduced. Can be.

The idler shaft 64 and the cam shaft 53 are assembled on the split surface A of the crankcase 42, which is the mating surface, and on the mounting surface B between the cylinder 45 and the cylinder head 43, so that the assemblability is improved.

The cam shaft 53 and the idler shaft 64 are on the side where the plane including the split surface A and the plane including the mounting surface B intersect with respect to the axis C2 of the cylinder 45, that is, the split surface A and the mounting surface B Because it is located on the approaching side,
The idler shaft 64 supported on the split surface A and the cam shaft 53 supported on the mounting surface B can be arranged close to each other, and another intermediate shaft is provided between the idler shaft 64 and the cam shaft 53. Both can be directly connected by the small gear 66 and the cam gear 67 without any intervention. Therefore, the height of the cylinder 45 in the direction of the axis C2 can be kept low, and the size of the power unit 7 extending in the left-right direction is reduced, so that the power unit 7 is compact. Also, the number of parts can be reduced because the intermediate shaft is not required.

The cam shaft 53 and the idler shaft 64
Is a cylinder 45 inclined upward and to the right from the crankshaft 31.
, The center of gravity of the power unit 7 can be lowered.

Further, an idler shaft 64, which is a coaxial two-axis rotary shaft having a plurality of functions, is provided in a narrow space between the split surface A and the mounting surface B on the intersecting side of the cylinder 45. Are arranged in a concentrated manner, a wide space without a rotation axis can be formed on the side surface of the cylinder 45 on the opposite side, and peripheral components can be arranged in the space.

The upper crankcase 42 and the cylinder head 4
The radiator 41 can be compactly arranged here by utilizing the V-shaped space formed by the power unit 3 and the power unit 7 can be made compact.

Since the cam shaft 53 is disposed on the mounting surface B between the cylinder 45 and the cylinder head 43, the height of the cylinder head 43 can be reduced, and the cam shaft 53 is
The compact internal combustion engine 30 can be obtained in combination with the arrangement in the narrow space between the split surface A and the mounting surface B on the intersecting side of the cylinder 45.

Since the center shaft 93 and the idler shaft 64 of the transmission 91 are arranged on both sides of the crankshaft 31 as compared with the case where two rotating shafts are arranged only on one side of the crankshaft 31. In addition, the overhang dimension of the power unit 7 in the left-right direction can be reduced, and the power unit 7 can be made compact.

When the idler shaft 64 provided in the drive mechanism for driving the cam shaft 53 is a coaxial two-axis rotary shaft, the idler shaft 64 can also function as a drive shaft of the cooling water pump 79 and a balancer shaft. . As a result, the cost can be reduced as compared with a case where a rotating shaft having these functions is provided separately from the idler shaft 64.

FIG. 4 is a diagram for explaining the second embodiment of the present invention, and is a diagram corresponding to FIG. 3 of the first embodiment. The power unit 7 of the second embodiment is different from the power unit 7 of the first embodiment in the structure of the power transmission device, and the other structures are basically the same.
The same reference numerals are given to the same structures as in the first embodiment, and detailed description thereof will be omitted.

The power transmission device 120 according to the second embodiment includes a hydraulic transmission 121 having a swash plate. The transmission 121 includes an input gear 122, a constant displacement swash plate hydraulic pump 123, a variable displacement swash plate hydraulic motor 124, and an output shaft 125. The output shaft 125 whose axis C7 is oriented in the front-rear direction of the vehicle body is connected to the transmission 1
21 is a central axis, the front end of which is a bottomed semi-cylindrical shape formed on the inner surface of the front end of each of the crankcases 42U, 42L on the split surface A of the upper and lower crankcases 42U, 42L. The rear end portion of the transmission case 127 is supported by a support shaft inserted into a hole in the rear end surface of the transmission case 127 via a bearing 128. Therefore, the axis C7 of the output shaft 125 is located on the split plane A of the upper and lower crankcases 42U and 42L.

Since the front end of the output shaft 125 is supported by the front ends of the crankcases 42U and 42L, the front end of the output shaft 125 is located forward of the rear end of the crankshaft 31 in the vehicle body. positioned. Therefore, since the crankshaft 31 and the output shaft 125 can be arranged so as to overlap in the front-rear direction, the length of the power unit 7 in the front-rear direction can be reduced, and the power unit 7 can be made compact.

The second drive gear 61 attached to the crankshaft 31 is engaged with an input gear 122 formed integrally with the housing 123a of the hydraulic pump 123. A starting driven gear 129 that meshes with a small gear of an idler shaft constituting a reduction mechanism of the starting motor is mounted on a front portion of the housing 123a via a one-way clutch 130. The transmission of the rotation of the starting motor at the time of starting is the same as that of the first embodiment.

The hydraulic pump 123 includes a housing 123a
A swash plate 123c for driving a plurality of pistons 123b is provided therein. When the housing 123a rotates, the swash plate 123c is tilted and each piston 123b is driven to generate high oil pressure. Also, the hydraulic motor 124
Cylinder block 12 having a plurality of pistons 124b
4a and a swash plate 124c. The cylinder block 124a is integrally connected to the output shaft 125.

The hydraulic pressure from the hydraulic pump 123 is supplied to a hydraulic motor 124 under the control of a control valve, and the pistons 124b are driven to abut against the swash plate 124c, whereby the cylinder block 124a rotates and is integrated therewith. Output shaft 125 rotates. The rotation of the output shaft 125 is continuously variable by changing the angle of the swash plate 124c by an actuator. Further, by the control valve,
The output shaft 125 is prevented from rotating, that is, the input gear 1
The rotation of the motor 22 may not be transmitted to the output shaft 125.

The output gear 131 attached to the output shaft 125 of the hydraulic transmission 121 meshes with a gear fixed to the drive shaft 141 of the final reduction gear 140. A bevel gear 141a formed at the rear end of a drive shaft 141 whose axis C8 is oriented in the front-rear direction of the vehicle body.
Are engaged with the driven bevel gear 142 attached to the axle 143 of the rear wheel 6. Thus, the output shaft 12
5 is decelerated, and the rear wheel 6 is driven. At this time,
As in the first embodiment, the axis C1 of the crankshaft 31 is
By positioning the drive unit 141 below the axis C8 of the drive shaft 141, it is possible to reduce the center of gravity of the power unit 7, that is, the center of gravity of the vehicle body.

For controlling the internal combustion engine 30 and the transmission 121, a rotation speed sensor 144 for detecting a rotation signal of the drive shaft 141 is provided in the case of the final reduction gear 140.
Is mounted, and the transmission 1 is
The rotation speed of the output shaft 99 is detected.

In the second embodiment, the same effects as in the first embodiment can be obtained, and the length of the hydraulic transmission 121 in the front-rear direction is shorter than that of the planetary gear transmission 91 of the first embodiment. Therefore, the power unit 7 can be made more compact.

In the first and second embodiments, the center shaft 93 of the planetary gear transmission 91, the output shaft 125 of the hydraulic transmission 121, and the idler shaft 64 are supported by the split surface A of the crankcase 42. , At a position other than the split plane A,
It may be supported by the crankcase 42. Similarly,
The cam shaft 53 may be supported only by the cylinder head 43 instead of the mounting surface B.

The motorcycle 1 may be a type of motorcycle other than the scooter type.

[Brief description of the drawings]

FIG. 1 is a left side view of a scooter type motorcycle on which a power unit according to a first embodiment of the present invention is mounted.

FIG. 2 is a schematic view of a main part, mainly showing gear engagement when the crankcase and the cylinder head are cut along the line II-II in FIG. 1;

FIG. 3 is a sectional view taken along line III-III in FIG. 2;

FIG. 4 is a cross-sectional view corresponding to FIG. 3 of a power unit of a motorcycle according to a second embodiment of the present invention.

[Explanation of symbols]

1 ... motorcycle, 2 ... bolt, 3 ... front frame,
4 Rear frame, 5 Front wheel, 6 Rear wheel, 7 Power unit, 8 Seat, 9 Front fender, 10 Front cover, 11 Step floor, 12 Frame body cover, 13 Rear fender, 14 Side cover , 15 ... storage box, 16 ... swing arm, 17
... Buffer, 18 ... King pin, 19 ... Axle holder, 2
0: axle, 21: head pipe, 22: handle post, 23: steering arm, 24: link, 25 ...
Bracket, 26 ... Hanger hole, 27 ... Buffer, 30 ...
Internal combustion engine, 31 ... crankshaft, 32 ... air cleaner, 3
3 ... air introduction pipe, 34 ... throttle body, 35 ... intake pipe, 36 ... fuel injection valve, 37 ... fuel tank, 38 ... exhaust pipe, 39 ... exhaust muffler, 40 ... fan cover, 41 ... radiator, 42 ... crankcase 43, cylinder head, 44, cylinder head cover, 45, cylinder, 4
6 ... pipe bush, 47 ... piston, 48 ... connecting rod,
49, 50: Main bearing, 51: Spark plug, 52: Supercharger, 5
3: cam shaft, 54, 55: bearing, 56: alternator, 5
7 ... nut, 58 ... cooling fan, 59 ... bolt, 60,
61: drive gear, 62: oil pump, 63: suction passage, 64: idler shaft, 65, 66, 67: gear, 68
... intake valves, 69 ... supercharged valves, 70, 71 ... intake rocker arms, 72 ... rods, 73, 74 ... supercharged rocker arms, 7
5: Rod, 76: Rotational position sensor, 77, 78: Bearing, 79: Cooling water pump, 80: Water pipe, 81: Discharge hole, 82: Thermostat, 83: Weight, 90: Power transmission device, 91: Planetary gear Type transmission, 92: transmission case, 93: center shaft, 94: input gear, 95: starting clutch, 96, 97, 98: transmission clutch, 99: output shaft, 100: detent member, 101: boss with flange , 102: pinion, 103, 104, 105: gear, 106: one-way clutch, 107: output gear, 11
0: Final reduction gear, 111: Drive shaft, 112: Gear, 113: Rotation speed sensor, 120: Power transmission device, 1
21: hydraulic transmission, 122: input gear, 123: swash plate hydraulic pump, 124: swash plate hydraulic motor, 125:
Output shaft, 126 ... bearing, 127 ... transmission case, 128
... Bearing, 129 ... Gear, 130 ... One-way clutch, 13
DESCRIPTION OF SYMBOLS 1 ... Output gear, 140 ... Final reduction gear, 141 ... Drive shaft, 142 ... Gear, 143 ... Axle, 144 ... Rotation speed sensor, A ... Split surface, B ... Mounting surface, C0 ... Body center, C1
~ C8 ... axis.

Claims (2)

[Claims] 1. An internal combustion engine having a crankshaft having an axis oriented in the front-rear direction of a vehicle body, and a power transmission device for transmitting power of the crankshaft to rear wheels, and disposed below the vehicle body. In the power unit for a motorcycle, the axis of the crankshaft is disposed near the center of the vehicle body, and the cylinder of the internal combustion engine is arranged such that the axis of the cylinder is one of the left and right directions of the vehicle body with respect to the axis of the crankshaft. And the power transmission device is arranged so as to be inclined upward, and in the power transmission device, an axis of a central axis of a transmission provided in the power transmission device is disposed in a left-right direction of the vehicle body with respect to an axis of the crankshaft. In the other direction and obliquely upward, the vehicle body is disposed so as to be directed in the front-rear direction, and a front end of the center shaft is located forward of a rear end of the crankshaft. The power unit of a motorcycle that. 2. The axle of the rear wheel is driven via a shaft drive mechanism of the power transmission device, and the axis of the crankshaft is disposed below the axis of the drive shaft of the shaft drive mechanism. The motorcycle power unit according to claim 1, wherein: