JPH10119591A - Power unit for astride riding type vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve cooling performance as the whole of an engine by arranging an exhaust pipe and a valve gear on the side wall on the side of the inclined direction of a cylinder block erected to be inclined to one side of the left and right sides of a car body. SOLUTION: A crankshaft 11 is arranged so that both the ends may be turned to the front and back directions of a vehicle and a cylinder block 10 is arranged so as to be inclined to the right side of a car body. An exhaust pipe 12 is arranged adjacently to the right side wall 102 on the side of the inclined direction of the cylinder block 10 and push rods 80i and 80o are stored at the inside of the right side wall 102 . Because the right side wall 102 of the cylinder block 10 inclined to the right side becomes smaller in space of the up and down directions and ill ventilated and the left side wall 103 of the cylinder block 10 becomes larger in space of the up and down directions and well ventilated, the left side wall 103 considerably affects cooling effects of the cylinder block. In the case of these arrangements, influence by the arrangements is suppressed to a minimum and cooling effects as the whole of an engine E can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power unit for a saddle-ride type vehicle, and more particularly to a power unit for a saddle-ride type vehicle which is arranged close to a side wall of a cylinder block which stands upright and inclined to one side. .

[0002]

2. Description of the Related Art Such a power unit for a straddle-type vehicle has
For example, as disclosed in JP-A-7-105949, it is already known.

[0003] A saddle-ride type vehicle that often travels on uneven terrain has to prevent the exhaust pipe from interfering with unevenness or obstacles on the ground.
The exhaust pipe is arranged along the side wall of the cylinder block that stands upright from the casing. In the prior art described in the above publication, an exhaust pipe is arranged along a left side wall of a cylinder block that stands upright on a vehicle body left side.

If the cylinder block is erected to the left side of the vehicle as in the prior art, for example, the space in the vertical direction of the right side wall of the cylinder block can be increased and the ventilation of that portion can be improved. The cooling effect of the engine on the wall is improved as compared with the left side wall where the space in the vertical direction is small and the ventilation is poor. Therefore, if the exhaust pipe is arranged along the left side wall where the cooling effect is poor, the right side wall of the cylinder block which has a high cooling effect and greatly affects the cooling performance of the engine is less likely to be affected by the heat of the exhaust pipe. Cooling performance can be improved.

[0005]

However, in the above prior art, since the push rod of the valve train is arranged on the right side wall of the cylinder block opposite to the exhaust pipe, the cooling performance of the engine is greatly affected. There is a possibility that the cooling effect of the right side wall of the cylinder block exerted by the housing space for the push rod is hindered, and the cooling performance of the entire engine cannot be sufficiently exhibited.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to improve the cooling performance of an engine by considering the arrangement of an exhaust pipe and a valve train with respect to the direction of inclination of a cylinder block. I do.

[0007]

According to the first aspect of the present invention, the exhaust pipe and the valve train are arranged on the side wall on the side of the inclination direction of the cylinder block which is erected so as to be inclined to the left or right of the vehicle body. The side wall on the opposite side of the cylinder block, which has a large space in the vertical direction and has a large effect on the cooling performance of the engine, is not affected by the exhaust pipe and the valve mechanism, and the cooling performance of the entire engine is improved. In addition, since the valve mechanism is disposed on the side wall on the inclined direction side of the cylinder block, the length of which is reduced in the vertical direction, the length can be shortened. Can be made more compact in the vertical direction.

According to the second aspect of the present invention, since the camshaft rotated by the crankshaft and the rotating shaft of the transmission are concentrated on the inclined side of the casing, the concentration of the weight and the concentration of the bearing are performed. Thus, the strength of the casing only needs to be partially increased, which is advantageous in terms of strength and weight. In addition, the cam shaft and the rotating shaft can be concentrated and lubricated by the oil returning from the upper portion of the cylinder block to the casing, which is advantageous in terms of lubrication efficiency.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

1 to 30 show an embodiment of the present invention. FIG. 1 is a left side view of a saddle-ride type vehicle, FIG. 2 is a plan view of the saddle-ride type vehicle, and FIG. 4 is a rear view of the saddle-ride type vehicle, FIG. 5 is a left side view of the saddle-ride type vehicle with the body removed, FIG. 6 is a bottom view of the saddle-ride type vehicle with the body removed, and FIG. 8 is an enlarged sectional view of a main part of FIG.
9 is a sectional view taken along line 9-9 of FIG. 8, FIG. 10 is a sectional view taken along line 10-10 of FIG. 8, FIG. 11 is an enlarged view of a main part of FIG. 8, and FIG. 13 is a sectional view taken along line 13-13 of FIG. 12, FIG. 14 is an enlarged view of a main part of FIG. 9, FIG. 15 is a view taken along line 15-15 of FIG. 14, and FIG. FIG. 17 is a sectional view taken along line 17-16 of FIG.
FIG. 18 is a sectional view taken along line 18-18 of FIG. 17,
FIG. 19 is a view taken along line 19-19 of FIG. 17, and FIG.
FIG. 21 is a sectional view taken along line 21-21 of FIG. 17,
FIG. 22 is an enlarged view of a main part of FIG. 10, and FIG.
FIG. 24 is a view taken in the direction of the arrow 23, FIG.
25 is a sectional view taken along line 25-25 of FIG. 10, and FIG.
27 is an enlarged sectional view taken along line 27-27 in FIG. 5, FIG. 28 is an enlarged sectional view taken along arrow 28 in FIG. 27, FIG. 29 is an enlarged sectional view taken along line 29-29 in FIG. Is 30- in FIG.
It is a 30-line enlarged sectional view.

First, a straddle-type vehicle V will be described with reference to FIGS.
Will be described.

The straddle-type vehicle V has a body frame F assembled by welding steel pipes, and a pair of left and right front wheels Wf, Wf and rear wheels Wr, Wr are suspended at the front and rear portions, respectively. Balloon type low pressure tires are mounted on these wheels. A steering handle 1, a fuel tank 2, and a straddle-type seat 3 are arranged in the upper part of the body frame F in order from the front. A brake lever 4 is provided at the right end of the steering handle 1, and a brake lever 5 is provided at the left end.
The latter brake lever 5 can be used as a reverse shift lever only when the reverse spin is depressed. A central portion of the steering handle 1 is covered with a handle cover 6, and various indicators 7 are provided at a rear portion thereof, and a meter 8 is provided so as to protrude forward.

A power unit P having an engine E for driving left and right rear wheels Wr, Wr is mounted in the center of the body frame F below the fuel tank 2 and the seat 3. The power unit P includes a casing 9 that also serves as a crankcase and a transmission case, and a cylinder block 10 that stands up from the casing 9, and a crankshaft 11 (see FIGS. 8 and 9) supported by the casing 9 extends in the vehicle longitudinal direction. , And the cylinder block 10 stands upright inclining rightward in the vehicle body with respect to the vertical direction (see FIG. 4). The exhaust pipe 12 connected to the front surface of the cylinder block 10 is bent 180 ° to the right, extends to the right side of the cylinder block 10 to the rear of the vehicle body, and is connected to a muffler 13 provided at the rear right side of the vehicle body.

Step bar 1 for supporting both feet of rider
4 and 14 are fixed to the body frame F so as to cross the lower surface of the power unit P,
, A change pedal 16 is provided adjacent to the left step bar 14. An air cleaner 17 disposed above and behind the power unit P is connected to a rear surface of the cylinder block 10 of the engine E via a carburetor 18. The intake duct 19 of the air cleaner 17 extends diagonally forward on the left side of the vehicle body,
Its tip opens to the rear of the fuel tank 2. A battery 20 for supplying power to various electric components is mounted on the rear part of the vehicle body.

A synthetic resin body B supported by the body frame F includes a front fender 21 that covers from the upper part of the left and right front wheels Wf, Wf to the upper part of the fuel tank 2 and the upper part of the left and right rear wheels Wr, Wr. A rear fender 22 to cover;
A pair of left and right first side covers 23, 23 that connect the front fender 21 and the rear fender 22 to cover the side of the vehicle body below the seat 3, and a pair of left and right second side covers connected to the left and right front portions of the rear fender 22 24, 24
It is composed of A tail lamp 25 is provided at a rear end of the rear fender 22. A front carrier 26 and a rear carrier 27 are provided above the front fender 21 and the rear fender 22, respectively. The lower surface of the power unit P is protected by an underguard 28 (see FIG. 6) made of a metal plate having a large number of holes.

As is apparent from FIGS. 3 and 5, the front wheel suspension device is of a double wishbone type and has a symmetrical structure. The upper arm 32 has a base end pivotally supported by a frame member 31, respectively. A lower arm 34 whose base end is pivotally supported by the frame member 33;
2 and a ball joint 35 at the tip of the lower arm 34.
A knuckle 37 pivotally supported via a, and a front cushion 39 whose lower end is connected to the upper arm 32 and whose upper end is connected to the frame member 38. The knuckle 37 is integrally formed with a knuckle arm (not shown) interlocked with the steering handle 1 via a link mechanism. When the steering handle 1 is rotated, the knuckle 37 is
The front wheel Wf is turned around the axis 41 connecting the ball joints 36 with the front wheel Wf.

As is apparent from FIGS. 5 and 7, the rear wheel suspension device comprises a pivot tube 43 rotatably supported at both ends by frame members 42, 42, and a left end portion of the pivot tube 43 on the left axle case. A left arm tube 46 connected to the shaft tube 44;
3 is connected to a gear housing 45 provided on the left and right axle cases 44, 44;
A connecting member 48 for connecting and reinforcing the 6 and the right arm tube 47;
And a rear cushion (50) connecting between the frame member (49) and the gear housing (45). Right arm tube 47 is left arm tube 4
6, and a propeller shaft 52 is disposed so as to penetrate the hollow portion. Output 1 of transmission
02 ₁ of the rear end and Fuchs joint 54 connecting the propeller shaft 52, since the swing center is arranged to come onto the rotation axis X of the pivot tube 43 (see FIG. 7), the left and right arms tube When the wheels 46 and 47 rotate around the axis X together with the pivot tube 43, the propeller shaft 52 can bend at the hooks joint 54 accordingly, and the rear wheels Wr, Wr
Power transmission to the vehicle.

Rear axles 55, 55 are supported inside the axle cases 44, 44, and rear wheels Wr, Wr are connected to both ends of the rear axles 55, 55. Inside the gear housing 45, the gear housing 45
A drive bevel gear 57 provided on an input shaft 56 rotatably supported by the shaft and a driven bevel gear 58 provided on the rear axles 55, 55 mesh with each other. By coupling the rear end of the propeller shaft 52 to the rear end of the input shaft 56 by a coupling 59, the rotation of the propeller shaft 52 is transmitted to the rear axles 55, 55, and the rear wheels Wr, Wr are driven.

Next, a schematic structure of the power unit P will be described with reference to FIGS.

The power unit P is constructed by integrating an engine E and a transmission T with each other. That is, the crankcase of the engine E and the transmission case of the transmission T are integrated as a common casing 9, and mounting bosses 71, 71 are formed on both lower portions of the casing 9. Are connected via The casing 9 includes a front casing 121, a rear casing 122, a front cover 214, and a rear cover 215.
The recoil starter cover 216 is coupled to the rear cover 215.

The engine E has a cylinder 72 inside and a plurality of cooling fins 10 ₁ ... Formed on the outside, a cylinder head 73 joined to an upper end surface thereof, and a sliding inside the cylinder 72. Piston 74 connected to the piston 74 via a connecting rod 75, and the crankshaft 11
1 and a camshaft 77 that is driven in a decelerated manner via a silent chain 76.
7 is supported by the casing 9 connected to the lower end of the cylinder block 10. In the cylinder head 73,
Intake and exhaust valves 78i and 78o that open and close intake and exhaust ports
And rocker arms 79i, 79o for opening and closing them.
The rocker arms 79i and 79o are driven by a cam shaft 77 via push rods 80i and 80o. An ignition plug 211 is provided near the left side of the vehicle body of the cylinder head 73. A head cover 212 is coupled to an upper end of the cylinder head 73.

As apparent from FIG. 8, the engine E
, The crankshaft 11 is disposed with its both ends facing the front-rear direction of the vehicle, and the cylinder block 10 is moved toward the transmission T where the cylinder axis Y is disposed on one side of the crankshaft 11, ie, It is arranged to be inclined to the right.
The right side wall 10 of the cylinder block 10 on the tilt direction side
₂ and an exhaust pipe 12 is arranged in the vicinity of the right side wall 1.
0 ₂ of the pushrod receiving space 10 ₄ to the push rod 80i formed vertically therein, 80o is housed. Note that reference numeral 213 in FIG. 8 is a breather chamber.

By the way, while the right side wall 10 ₂ of the cylinder block 10 is inclined to the right to become worse and decreases the space in the vertical direction ventilation, the left side wall 10 ₃ of the cylinder block 10 and ventilated space in the vertical direction is increased since the better, the left side wall 10 ₃ would greatly affects the cooling effect of the cylinder block 10.
Accordingly, the cylinder block 1 by temporarily exhaust pipe 12 and the push rod 80i on the left side wall 10 ₃ of the cylinder block 10, placing 80o, reduction of heat dissipation due to heat or the push rod housing space 10 ₄ received from the exhaust pipe 12
0 cooling effect is reduced. However, in this embodiment, the exhaust pipe 12 and the push rod 80i in the right side wall 10 ₂ is less affected on the cooling effect of the cylinder block 10, so positioned serves to 80o, the entire engine E to minimize their impact Cooling performance can be improved. Incidentally, the cooling fins 10 ₁ and 6 protrude to the left side wall 10 ₃ in the present embodiment, the cooling fins 1 on the right side wall 10 ₂
5 protruding 0 ₁

The rotor 82 of the generator 81 is fixed to the rear end of the crankshaft 11, and the stator 83 thereof is fixed to the casing 9. A generator 8 is mounted on the crankshaft 11.
A large-diameter starting gear 85 is rotatably supported adjacent to one rotor 82, and the starting gear 85 is a one-way clutch 86
Through the rotor 82. This starting gear 8
5 is a starter motor 8 attached to the outside of the casing 9
7 is connected to an output shaft 88 via a reduction gear device 89. The reduction gear device 89 includes two idle shafts 89 ₁ , 89
_It consists of a plurality of idle gears supported on ₂ . Therefore, if the start gear 85 is driven by the operation of the starter motor 87, the crankshaft 11 can be cranked via the one-way clutch 86 and the rotor 82. When the engine E starts, the one-way clutch 86 is in a free state, and the transmission of rotation from the rotor 82 to the starting gear 85 is cut off.

Further, a starting wheel 90 is fixed to the rearmost end of the crankshaft 11, and a recoil starter 91 which can engage with the starting wheel 90 is attached to the casing 9. Therefore, the crankshaft 11 can be cranked by pulling the rope of the recoil starter 91.

At the front end of the crankshaft 11, a centrifugal starting clutch 92 is attached. Also, the front casing 121
The oil pump 93 provided at the lower part of the crankshaft 1
1 is driven through a silent chain 94.

The transmission T has a main shaft 101, a sub shaft 102, and a reverse shaft 103, and these shafts 101, 1
02 and 103 are supported by the casing 9 in parallel with the crankshaft 11. The main shaft 101 is supported by the front casing 121 and the rear casing 122 via a pair of ball bearings 217, 217, and the sub shaft 102 is supported by the front casing 121 and the rear casing 122 via a pair of ball bearings 218, 218. You. At this time, the shafts 101, 102, and 103 are arranged on the same side of the crankshaft 11 as the camshaft 77 (that is, on the right side of the vehicle body) and lower than the camshaft 77. More specifically, the main shaft 1
01 is disposed, and the sub shaft 102 is further lower right of the main shaft 101.
Is arranged, and a reverse shaft 103 at the upper right of the sub shaft 102 is arranged. The lower right of the crankshaft 11 and the main shaft 1
A shift drum 104 operated by the change pedal 16 is disposed below and to the left of 01.

Since the camshaft 77, the main shaft 101 and the sub shaft 102 driven by the crankshaft 11 are concentrated on the right side of the casing 9 of the casing 9, the mass of the rotating part and the concentration of the bearings are increased. It is only necessary to partially increase the strength of the engine 9, and the weight of the other parts can be reduced to reduce the weight of the engine E as a whole. Moreover Oil camshaft 7 falling from the push rod housing hole ₁₀₄ formed in the cylinder block 10
7. The lubrication effect can be enhanced by effectively acting on the main shaft 101 and the sub shaft 102.

At the rear end of the sub shaft 102, a vehicle speed sensor 95 for detecting the vehicle speed based on the rotation speed of the sub shaft 102 is provided. The vehicle speed sensor 95 is bolted to a counter shaft protector 96 mounted on the rear surface of the rear casing 122 via a bakelite heat insulating material 97, and the counter shaft 102.
Detecting the projections 102 ₂ ... projecting from the rear periphery of. By making the inner diameter of the rear casing 122 side of the sub-shaft protector 96 smaller than that of the seal member 98 between the counter-shaft protector 96 and the rear casing 122 and sandwiching the seal member 98, the oil of the transmission T Shaft protector 9
6 can be prevented and the vehicle speed sensor 95 can be used in a dry state.

A multi-plate type transmission clutch 105 is attached to one end of the main shaft 101, and an input member 106 of the transmission clutch 105 and an output member 107 of the starting clutch 92 are connected via a reduction gear unit 108. The speed change clutch 105 is opened and closed by the change pedal 16.

Between the main shaft 101 and the sub shaft 102, both shafts 101,
1 to 5 speed transmission gear trains 109 ₁ to 109
109 ₅ is provided. The rear end of the sub shaft 102 projects rearward from the casing 9, and the front end of the propeller shaft 52 is connected to an output portion 102 ₁ at the rear end.

As is apparent from FIG. 14, a reverse gear train 109r is provided over the main shaft 101, the reverse shaft 103, and the sub shaft 102. The reverse gear train 109r is provided with a drive gear 1 formed on the main shaft 101.
10 (see FIG. 9), a stepped idle gear 111 rotatably supported on the reverse shaft 103, and rotatably supported on the sub shaft 102, and meshing with the drive gear 110 via the idle gear 111. And a driven gear 112. The first speed gear train 109 is provided on the counter shaft 102.
_A dog clutch body 114 is slidably and spline-fitted between _one driven gear 113 and the driven gear 112 of the reverse gear train 109r. When the dog clutch body 114 is engaged with the driven gear 113, When the gear train 109 ₁ is established and the dog clutch body 114 is engaged with the driven gear 112, the reverse gear train 109r is established.

The detailed structure of each part of the power unit P will be described below.

First, the structure of the lubrication system of the power unit P will be described with reference to FIGS.

As shown in FIGS. 11 to 13, the casing 9 has a front casing 121 and a rear casing 122 which are divided into front and rear sides with respect to the cylinder axis Y (see FIG. 10).
Is provided. In the oil pan 123 at the bottom of the casing 9, an oil suction space 126 is defined by partitions 124, 125 formed near the mating surface of the casings 121, 122. Oil suction space 126 is partitioned into the lower oil chamber 127 and upper oil chamber 128 by a partition wall 125 ₁ extending in the horizontal direction provided in the partition wall 125 of the rear casing 122, a front casing 121 to the front wall of the lower oil chamber 127 A front suction hole 124 ₁ communicating with the inside of the lower oil chamber 127 is formed.
Rear suction hole 125 ₂ communicating with the interior of the rear casing 122 to the rear wall is formed. Sectional area of the front suction port 124 ₁ is formed larger than the cross-sectional area of the rear intake port 125 _2. This is because the starting clutch 92 and the shifting clutch 10
5 is arranged on the front casing 121 side, so that oil easily accumulates at the bottom of the front casing 121, and the oil is effectively sucked into the oil suction space 126.

A groove 124 ₂ is formed in the inner periphery of the partition 124 of the front casing 121 formed in a horizontal U-shape, and an oil strainer 129 is mounted in the groove 124 ₂ . The oil strainer 129 includes a suction duct 130 formed by pressing a metal plate and a screen 131. Intake duct 130 has a flange portion 130 ₁ projecting horizontally on the outer periphery thereof, and a suction port 130 ₂ opening downward, also the screen 131 and the support frame 131 _1, which is formed by rubber, therein composed of stretched mesh-like screen body 131 ₂ which in.

Therefore, the flange 1 of the suction duct 130
In a state of 30 ₁ of the upper surface superimposing support frame 131 ₁ of the screen 131, after inserting them in the grooves 124 _{and second} partition wall 124 of the front casing 121 from the rear, by coupling the rear casing 122 to the front casing 121 If
Partition wall 125 ₁ of the rear casing 122 are in close contact with the rear edge of the flange portion 130 ₁ and the support frame 131 _1, the oil strainer 129 and the screen 131 are fixed.

As is apparent from FIG. 12, the suction duct 1
Inlet 130 ₂ 30 is front edges 130 ₃ high, are inclined to and rear sides 130 ₄ becomes lower, and easier to suck oil from the storage amount is large front casing 121 side of the oil .

As described above, the oil strainer 1 is located inside the oil suction space 126 partitioned by the partition walls 124 and 125.
Since the housing 29 is accommodated, it is possible to prevent the high-temperature oil dropped from above the engine E from being directly sucked into the oil pump 93, thereby improving the cooling performance of the engine E.

When assembling the oil strainer 129 to the casing 9, the suction duct 130 and the screen 131
And the groove 124 _{2 of the} front casing 121
, The rear casing 122 only needs to be connected to the front casing 121, so that the assemblability is extremely good. In addition, since the suction duct 130 and the screen 131 are formed by different members, the screen 131 can be shared by a plurality of models, and the versatility is improved.

Since the start clutch 92 and the speed change clutch 105 are provided at the front of the engine E, the amount of oil returning to the front casing 121 is larger than the amount of oil returning to the rear casing 122.
The cross-sectional area of the front suction port 124 ₁ formed in the front partition wall 124 is set larger than the cross-sectional area of the rear suction port 125 ₂ formed in the rear partition wall 125 of the oil suction space 126. 121 and rear casing 12
2 can be effectively returned to the oil suction space 126. For the above reason, the amount of oil stored in the front casing 121 side is
Becomes larger than the amount of oil is stored in the 2 side, by an inlet 130 and _second inlet duct 130 than the coupling surface of the front casing 121 and the rear casing 122 is provided with biased to the front, the front and rear of the engine E It is possible to avoid air biting at the time of inclination.

The suction duct 130 has a simple structure in which a metal plate is press-formed, and can be manufactured at low cost, and its shape can be easily changed. As shown by the broken line in FIG. 11, even if the suction duct 130 is mounted in a reversed state, the suction duct 130 interferes with the interference part 121 ₁ protruding from the inner surface of the front casing 121 at the G portion, so that erroneous assembly occurs. Is reliably prevented.

As is apparent from FIGS. 8 to 10, the oil pump 93 is composed of a well-known trochoid pump, and its suction port 132 faces the upper oil chamber 128 of the oil suction space 126, and its discharge port 133 is connected to the oil pump. It faces the discharge chamber 134. Oil passage L oil discharge chamber 134 which is open at the front end of the crankshaft 11 via the oil passage L _1
2 to lubricate the starting clutch 92 provided at the front end of the crankshaft 11 and
1 ₁ outer circumference to lubricate. The oil passage L branching from the oil passage L ₁
Numeral ₃ communicates with the cylinder head 73 via an oil passage (not shown) to lubricate the rocker arms 79i, 79o and the like provided therein.

The oil passage L ₄ extending from the discharge chamber 134 is
01 is communicated with the right end of the oil passage L ₅ formed therein to lubricate the speed change clutch 105 provided at the left end of the gear train and spindle 101 which is supported on the outer periphery of the main shaft 101. The oil passage L ₆ branching from the oil passage L ₄ are communicated with the oil passage L ₇ formed inside the reverse shaft 103, the reverse shaft 10
The lubrication of the idle gear 111 supported on the outer periphery of No. 3 is performed.

As is apparent from FIG. 14, the reverse shaft 1
Oil leaking from the sliding surface between the gear 03 and the idle gear 111 moves downward along the inner wall of the casing 9 (arrow a in FIG. 14).
Direction), and an oil passage L ₈ formed inside the counter shaft 102.
To lubricate the gear group supported on the outer periphery of the counter shaft 102. At this time, in order to guide the oil flowing down along the inner wall of the casing 9 the oil passage L ₈ counter shaft 102, the guide means of the oil are provided. That is, as is clear from FIGS. 14 to 16, a pair of guide ribs 135 and 136 whose intervals are narrowed downward in a reverse C-shape project downward from the inner wall of the casing 9 below the reverse shaft 103. Guide grooves 137,1 formed between guide ribs 135,136
38 is communicated with the end of the oil passage L ₈ countershaft 102. Thus, it is possible by a set of oil flowing down in the direction of arrow b in FIG. 15 guided in the direction of the arrow c, effectively supplied to the oil passage L ₈ countershaft 102.

Next, the structure of the transmission mechanism of the transmission T of the power unit P will be described with reference to FIGS.

As shown in FIG. 17, a change pedal shaft 141 to which the rear end of the change pedal 16 is connected is rotatably supported on the left side surface of the rear cover 215 of the casing 9. The collar 142 ₁ of the drive arm 142 is fitted and fixed with the bolt 143. Change pedal shaft 141 is biased toward the outside of the casing 9 by the spring 144, the end face the rear cover 21 of the collar 142 ₁ This biasing force
5 is brought into contact with the inner surface of the change pedal shaft 14.
1 play is prevented.

As is apparent from FIGS. 17 and 21, a shift shaft 145 extending in the vehicle longitudinal direction is rotatably supported by the casing 9, and a long hole 146 of a driven arm 146 fixed to a rear portion of the shift shaft 145. ₁ engages with the tip of the drive arm 142. Therefore, when the rider pushes down or pushes up the change pedal 16 with his / her feet, the movement of the change pedal 16 is changed by the change pedal shaft 14.
1, transmitted to the shift shaft 145 via the drive arm 142 and the driven arm 146 to reciprocate the shift shaft 145. When the rider presses down the change pedal 16 with his / her foot, a stopper 9 ₁ (see FIG. 21) with which the tip of the driven arm 146 abuts is provided on the inner surface of the casing 9 so that excessive torque is not transmitted to the shift shaft 145. It is formed.

As is apparent from FIGS. 17 and 18, an L-shaped first arm member 147 is spline-connected to the tip of the shift shaft 145. A support shaft 148 extending in the vehicle longitudinal direction is rotatably supported by the casing 9, and an L-shaped second arm member 149 is fixed to the support shaft 148. The first arm portion 147 ₁ of the roller 150 provided at the tip of the first arm member 147 engages the first arm portion 149 ₁ of the long hole 149 ₃ formed on the tip of the second arm member 149.
The support shaft 151 facing the shaft end of the main shaft 101 is
The roller 153 provided at the tip of the second arm 149 ₂ of the second arm member 149 engages with the notch 152 ₁ of the movable cam plate 152 rotatably supported on the support shaft 151.

As is clear from FIG. 9 as well,
A fixed cam plate 154 facing the movable cam plate 152 is supported on the support shaft 151, and a ball 155 is disposed between the two cam plates 1652 and 154. A sliding shaft 156 slidably fitted to the shaft end of the main shaft 101 is connected to the movable cam plate 152, and the movable cam plate 152 and the clutch piston 157 of the transmission clutch 105 are connected via a connection plate 158. Is done.

When the change pedal shaft 141 rotates in either the forward or reverse direction by operating the change pedal 16, the movable cam plate 152 rotates via the first arm member 147 and the second arm member 149. The movable cam plate 152 includes a fixed cam plate 154 and a ball 155.
As a result, the slider slides in the direction approaching the main shaft 101 together with the sliding shaft 156 against the urging force of the clutch spring 139 due to the reaction force received from the clutch spring 139. As a result, the clutch piston 157 connected to the movable cam plate 152 moves rightward (to the rear of the vehicle body) in FIG. 9, and the engagement of the transmission clutch 105 is released.

As shown in FIG. 17, the shift drum 159
The shift fork shaft 160 is supported inside the casing 9 in the longitudinal direction of the vehicle body. Three cam grooves 159 _{1 to} 159 ₃ are formed on the outer periphery of the shift drum 159, and the three cam grooves 159 _{1 to} 159 ₃ are slidably supported by the shift fork shaft 160.
This shift forks 161, 162 and 163 are engaged to the each cam groove 159 _{1-159 3.}

As shown in FIGS. 19 and 20, a collar 164 is rotatably fitted to the outer periphery of the shift shaft 145.
A change arm 165 having a first opening 165 ₁ , a second opening 165 ₂ , a spring receiver 165 ₃ formed by bending an inner peripheral edge of the first opening 165 ₁ , and a roller 166. Is welded. Both ends of the torsion coil spring 167 supported on the collar 164, and both side portions of the stud bolt 168 penetrating loosely the first opening 165 ₁ is screwed to the casing 9, the spring receiving 165 ₃ of the change arm 165 Abut on both sides. Therefore, the change arm 165 in the neutral position has its first opening 16
5 When _one edge is swung in either direction to a position abutting the stud bolt 168, the change arm 16 is displaced to the spring receiver 165 ₃ torsion coil spring 167
A biasing force is generated for returning the center 5 to the center position.

The second arm portion 14 of the first arm member 147
7 first opening 165 of the _second tip change arm 165
₁ and is inserted between both ends of the torsion coil spring 167. Therefore, when the first arm member 147 fixed to the shift shaft 145 rotates in either the forward or reverse direction, the tip of the second arm 147 ₂ of the first arm member 147 becomes the first opening 165 ₁ of the change arm 165. the inner predetermined distance lost motion, the second arm portion 147 ₂ tip first opening 1
When contact 65 ₁ of the inner edge rotates the change arm 165 in the forward and reverse directions. Second arm 1 of first arm member 147
While the 47 ₂ is lost-motion, the change arm 165 is held in the stopped state to the neutral position, the shifting clutch 1 therebetween
05 is released. Therefore, the transmission clutch 105
, The shift operation can be reliably started with a predetermined time lag.

Notch 169 formed at one end₁And the other end
Slot 169 formed_TwoAnd the opening 1 formed in the center
69_ThreeChange plate 169 with
Arranged between the end face of the ram 159 and the change arm 165
Is done. The change plate 169 has a notch 169₁Before
The outer periphery of the collar 164 is engaged with the_TwoTo
Engaged with the roller 166 of the change arm 165
In the state, the split
The notch 169 at the ring 170₁And slot 169 _TwoAlong
Biased in the direction. In this state, change arm 1
65 second openings 165_TwoAnd change plate 169
Opening 169_ThreeAre arranged at positions substantially overlapping with each other.

At the end of the shift drum 159, a star-shaped pin plate 171 is connected to a bolt 1 via a positioning pin 172.
Fixed at 73. A detent arm 175 pivotally supported on the casing 9 by a support shaft 174 is urged by a spring 176, and a detent roller 177 provided at the tip of the detent arm 174 has seven recesses 171 formed on the outer periphery of the pin plate 171. ₁ engages resiliently. Therefore, the shift drum 159 can stably stop at any one of the seven rotational positions corresponding to the seven shift positions.

On the end face of the pin plate 171, seven feed pins 171 ₂ ...
The pair of projections 16 engageable with the feed pins 171 ₂ .
9 _4, 169 _4, a pair of cam surfaces 169 _5, 169 ₅ and is formed on the inner periphery of the opening 169 ₃ of the change plate 169. In order to prevent the change plate 169 from dropping off the pin plate 171, a plate-shaped holder 178 for holding the outer surface of the change plate 169 is fastened together with the bolt 173.

In order to prevent the reverse gear from being established during forward running, a reverse shift restricting mechanism is provided. As is clear from FIGS. 10, 17 and 21, the reverse shift restricting arm 1 is attached to the casing 9 via the support shaft 179.
The reverse shift regulating arm 180 is biased toward the shift drum 159 by a spring 140. Shift drum 1
59 guide groove 159 ₄ at the rear periphery of the are is formed,
As the inside of the guide groove 159 ₄ tip of the reverse shift restricting arm 180 is the stopper 159 ₅ capable of contacting is projected. In Figure 21, by regulating the rotating end of the clockwise direction of the reverse shift restricting arm 180 by a stopper 219, so that the distal end of the reverse shift restricting arm 180 is not in sliding contact with the guide grooves 159 ₄ of the shift drum 159 . By doing so, the shift drum 15
9 can reduce sliding resistance when rotating, and can reduce shift load.

The shift drum 15 shown in FIG.
9 is rotated in the direction of arrow D to establish the reverse gear.
When the tip of the reverse shift regulating arm 180 is a guide groove
159 _FourStopper 159_FiveShift drum 1 in contact with
The rotation of 59 is regulated. At this time, the handle 1
Operate the reverse shift lever 5 (see FIGS. 1 and 2).
Then, a wire (not shown) is attached to the reverse shift lever 5.
The shaft 179 connected via the shaft rotates, and the reverse shift
The tip of the control arm 180 rotates in the direction of arrow E in FIG.
And the stopper 159_FiveDepart from. As a result,
The rotation of the left drum 159 in the direction of arrow D is allowed,
The establishment of the forward gear is allowed. Thus, the reverse
The establishment of the reverse gear is permitted only when the shift lever 5 is operated.
Prevents unexpected establishment of reverse gear
can do.

Next, the structure of the valve train will be described with reference to FIGS.

The front end and the rear end are ball bearings 181 and 182, respectively.
The camshaft 77 supported by 84 has a stepped portion 77 at its front end.
It comprises a small diameter portion 77 ₂ formed through a _1. In a state where the inner race 181 ₁ is fitted in the ball bearing 181 on the small-diameter portion 77 _2, color 1 on its distal end
83 is fixed by press fitting. A sprocket 186 is welded to the collar 185, and this sprocket 18
6 is the crankshaft 11 through the silent chain 76.
Connected to.

In order to support the ball bearings 181 and 182, support holes 183 ₁ and 184 ₁ having circular cross sections are formed in the support walls 183 and 184, respectively. On the side of the support hole 183 ₁ close to the sprocket 186, a stepped portion 183 ₂ by cutting out an end surface of the sprocket 186 side crescent
Is formed. The step 18 viewed from the center of the cam shaft 77
3 _second direction are silent chain 76 is coincident direction, i.e. in the direction of arrow F in FIG. 23 extending from the sprocket 186. The stepped portion 183 ₂ is the outer race 181 ₂ of the ball bearing 181 can be fitted.

When assembling the camshaft 77 to the casing 9, the camshaft 77 has a pair of ball bearings 181 and 182, a collar 185 and a sprocket 186.
Is assembled. Then, as shown in FIG. 24, the outer race 181 ₂ of the ball bearing 181 on the sprocket 186 side is engaged with the stepped portion 183 ₂ of the support hole 183 ₁ of the support wall 183 to temporarily hold the same, and the anti-sprocket 1
86 side of the ball bearing 182 in a state in which the support hole 184 has reduced the distance between the axes removed from the _first support wall 184, wrapped around the silent chain 76 to the sprocket 186. Then, the ball bearing 181 of the sprocket 186 side is moved in the direction indicated by the arrow H in FIG. 24, supporting remove the outer race 181 ₂ from the stepped portion 183 ₂ hole 183
₁ and the anti-sprocket 186
The ball bearing 182 on the side is supported by the support hole 1 of the support wall 184.
84 correctly by engaging the _1, completing the assembling of the camshaft 77.

By adopting the above structure, the camshaft 7
The ball bearings 181, 182 and collar 18
Even when the subassembly 5 and the sprocket 186 are assembled into a sub-assembly, the cam shaft 77 can be assembled without any trouble, and the number of parts and the number of assembling steps can be reduced. Incidentally, when you Kumitsukeyo the cam shaft 77 by the above method without providing the step portion 183 _2, the cam shaft at the time of assembly 7
7, the amount of movement in the axial direction increases, and the sprocket 186
In addition, stiffness is generated between the silent chains 76, and if the thickness of the support wall 183 is reduced to avoid this, the support rigidity of the cam shaft 77 is reduced.

As is apparent from FIG. 22, an intake cam 191i and an exhaust cam 192o are integrally formed on the cam shaft 77, and the intake cam 191i and the exhaust cam 19
A pair of valve lifters 19 driven in contact with 1o
2, 192 are slidably supported by the casing 9. Iron bolts 193 and 193 are screwed into the lower ends of the aluminum push rods 80i and 80o, and each of the bolts 193 has a spherical portion 19 formed at the tip of the head.
3 ₁ and includes a hexagonal and a chamfered portion 193 ₂ of the continuous thereto. And on the upper surface of each valve lifter 192, the spherical recess 1 the spherical portion 193 ₁ is fitted in the bolt 193
92 ₁ is formed. Also, two ribs 10 are provided so as to face the push rod storage space 10 ₄ of the cylinder block 10.
₅ and 10 ₅ are formed, and these ribs 10 ₅ and 10 ₅ are formed.
The lower end of ₅ protrudes so that it can contact the upper ends of valve lifters 192 and 192.

When the push rods 80i, 80o are pulled upward during maintenance, even if the valve lifters 192, 192 affixed to the push rods 80i, 80o move upward due to the viscosity of the oil, the rib 10 Push rod 80 blocked by ₅ and 10 ₅
i, 80o. As a result, the valve lifters 192 and 192 are prevented from dropping out of the mounting position, and wasteful time and labor required for reassembly can be reduced. The push rod 80i, so formed by the spherical portion 193 _1, 193 ₁ bolts 193, 193 of 80o, the push rod 80i, 8 including spherical portion
The weight can be reduced as compared with the case where the entirety is made of iron. Moreover, since the bolts 193, 193 is provided with a chamfered portion 193 _2, 193 ₂ of hexagonal a tool is engaged, the push rod 80i, coupling of the spherical portion 193 _1, 193 ₁ relative to the body portion of 80o also extremely easy .

Next, the structure of the chain tensioner of the silent chain 76 for driving the cam shaft 77 will be described with reference to FIGS. 25 and 26.

As shown in FIG. 25, a sprocket 194 provided on the crankshaft 11 and a sprocket 186 provided on the camshaft 77 are connected by a silent chain 76, and a sprocket 195 provided on the crankshaft 11 and an oil pump shaft 196 are provided. Is connected to the sprocket 197 provided by the silent chain 94.

As apparent from FIG. 26, a chain tensioner 198 for applying a predetermined tension to the silent chain 76 for driving the camshaft 77 has an L-shape whose center is pivotally supported by a support shaft 199. An arm 200 and a resilient means 201 for urging the arm 200 clockwise in FIG. 25 are provided. The spring means 201 includes bolts 202 and 2
The piston 200 has a piston rod 204 urged in a direction protruding from a cylinder 203 fixed at 02 by a spring (not shown). The shoe 205 provided at the other end is pressed against the silent chain 76.

[0070] During assembly of the resilient means 201, previously engaged with the Shisabotsu position against the piston rod 204 to the spring by screwing the bolt 206 into the bolt holes 203 ₁ of the cylinder 203, the resilient means After the assembly of the motor 201 is completed, the bolt 206 is removed, the piston rod 204 is protruded, and a predetermined tension is applied to the silent chain 76. As is clear from FIG.
Reference numeral 06 is located on the same plane as the gasket 208 sandwiched between the coupling surfaces of the casings 121 and 207.
If the casings 121 and 207 are to be joined together without removing the 06, the gasket 208 interferes with the bolts 206 and cannot be assembled, so that the forgetting to remove the bolts 206 can be prevented.

Next, the operation of this embodiment will be described.

While the engine E is idling, the rotational speed of the crankshaft 11 is low, and the centrifugal start clutch 92 is kept in the disengaged state, so that power transmission from the crankshaft 11 to the transmission clutch 105 is not performed.

[0073] If we raise the output of the established causes the engine E to the first speed gear train 109 ₁ of the transmission T in order to start the vehicle now automatically engaged starting clutch 92 by increasing the rotation speed of the crankshaft 11 becomes engaged state, the rotation of the crankshaft 11 starting clutch 72, reduction gear 108, it is transmitted to the main shaft 101 through a speed change clutch 105, and further transmitted from the first speed gear train 109 ₁ auxiliary shaft 102. As a result, the rotation of the sub shaft 102 is controlled by the propeller shaft 52, the drive bevel gear 57,
The power is transmitted to the rear wheels Wr, Wr via the driven bevel gear 58 and the rear axles 55, 55, and the vehicle starts.

Transmission gear trains 109 ₁ to 10 0 during running
9 _5, 109r shift is performed as follows. Rotated by the operation of the change pedal 16, 19, for example, the change arm 165 is rotated in the direction of arrow A, through the roller 166 and the long hole 169 ₁ to change plate 169 is the direction of arrow A to engage in the change arm 165 and, the opening 169 ₃ lower projections 169 ₄ formed presses one of the feed pin 171 ₂ upwardly, thereby rotating the shift drum 159 in only one pitch direction of arrow a. As a result, the detent roller 177 engages with the new concave portion 171 of the pin plate 171 and stably stops the shift drum 159 at the new position.

Release the depression of the change pedal 16
Arm with the resilient force of the torsion coil spring 167
165 rotates in the direction of arrow B toward the neutral position. this
Sometimes the change plate 169 also has the change arm 165
Both of them rotate in the direction of arrow B, but their openings 169_ThreeInto shape
Lower cam surface 169 formed_FiveIs one feed pin 171 _Two
To receive a reaction force by contacting the
19 while the spring 169 extends the spring 170.
Move in the direction of arrow C. Thereby, the cam surface 169
_FiveIs the feed pin 171_TwoOver the shift drum 1
With the 59 in the new position, change arm 1
65 and change plate 169 return to neutral position
be able to.

When, for example, the change arm 165 is rotated in the direction of arrow B by operating the change pedal 16, the shift drum 159 is rotated by one pitch in the direction of arrow B in the same manner as described above, and is stabilized at a new position. Stop. When the shift drum 159 rotates by one pitch in this manner, in FIG. 17, the three shift forks 161, 162, and 163 engaging with the cam grooves 159 _{1 to} 159 ₃ of the shift drum 159 slide in the axial direction. , Transmission T
To establish a predetermined gear position.

Next, the structure of the remaining portion of the engine E will be described with reference to FIGS.

In FIG. 27, reference numeral 221 is an intake port, reference numeral 222 is a bolt for connecting the head cover 212 to the cylinder head 73, reference numeral 223 is a knob of the recoil starter, and reference numeral 224 is a bolt for fixing the vehicle speed sensor 95.

In FIG. 28, reference numeral 225 denotes a rocker arm shaft, and reference numeral 226 denotes a rocker arm shaft fixing bolt.

In FIG. 29, reference numeral 227 denotes an exhaust port.

In FIG. 30, reference numeral 228 is an oil level gauge, and reference numeral 229 is a bolt for connecting the seal member 10 and the cylinder head 73 to the casing 9.

Next, another embodiment for preventing backlash of the change pedal shaft 141 will be described with reference to FIG.

In the first embodiment described above, the change pedal shaft 141 is urged by the spring 144 so that the drive arm 14
The end face of the second collar 142 ₁ is brought into contact with the inner surface of the rear cover 215 to prevent backlash (see FIG. 17). On the other hand, in the second embodiment, the change pedal shaft 141
1 of the drive arm 142 fixed to the bolts 143
42 ₁ of the end faces, the washer 220, respectively _1, 220
₂ , positioning surfaces 215 ₁ , 2 of the rear cover 215
By abutting to 15 _2, to prevent the axial play.

Although the embodiments of the present invention have been described in detail, various design changes can be made in the present invention without departing from the gist thereof.

For example, in the embodiment, the cylinder block 10
Is erected to the right of the vehicle body, but it may be erected to the left of the vehicle body.

[0086]

As described above, according to the first aspect of the present invention, since the exhaust pipe and the valve operating mechanism are arranged on the side wall on the inclined direction side of the cylinder block inclined to the left or right of the vehicle body, The long side wall on the opposite side of the cylinder block, which has a large length and greatly affects the cooling performance of the engine, is less susceptible to heat from the exhaust pipe and less susceptible to the reduction in heat radiation due to the storage space of the valve mechanism. Thus, the cooling performance of the entire engine is improved. In addition, the valve operating mechanism provided on the side wall on the inclined direction side of the cylinder block having a small vertical length can reduce the length.

According to the second aspect of the present invention,
Since the camshaft rotated by the crankshaft and the rotating shaft of the transmission are concentrated on the inclined side of the casing, it is only necessary to partially increase the strength of the casing, which is advantageous in terms of strength and weight. Not only that, the camshaft and the rotating shaft can be concentrated and lubricated by the oil returning from the upper part of the cylinder block to the casing, which is advantageous in terms of lubrication efficiency.

[Brief description of the drawings]

FIG. 1 is a left side view of a saddle-ride type vehicle.

FIG. 2 is a plan view of the saddle-ride type vehicle (a view in the direction of arrows in FIG. 1)

FIG. 3 is a front view of the saddle-ride type vehicle (a view in the direction of arrow 3 in FIG. 1);

FIG. 4 is a rear view of the straddle-type vehicle (a view in the direction of arrows in FIG. 1)

FIG. 5 is a left side view of the saddle type vehicle with the body removed.

FIG. 6 is a bottom view of the saddle type vehicle with the body removed (FIG. 5)
(View from 6 directions)

FIG. 7 is an enlarged sectional view of a main part of FIG. 2;

8 is an enlarged sectional view taken along line 8-8 in FIG. 5;

9 is a sectional view taken along line 9-9 in FIG.

FIG. 10 is a sectional view taken along line 10-10 of FIG. 8;

FIG. 11 is an enlarged view of a main part of FIG. 8;

FIG. 12 is a sectional view taken along line 12-12 of FIG. 11;

13 is a sectional view taken along line 13-13 of FIG.

FIG. 14 is an enlarged view of a main part of FIG. 9;

FIG. 15 is a view taken along line 15-15 of FIG. 14;

16 is a sectional view taken along line 16-16 of FIG.

FIG. 17 is an enlarged sectional view taken along line 17-17 of FIG. 8;

FIG. 18 is a view taken along line 18-18 of FIG. 17;

FIG. 19 is a view taken in the direction of arrows 19-19 in FIG. 17;

20 is an enlarged view of a main part of FIG. 17;

21 is a sectional view taken along line 21-21 of FIG. 17;

FIG. 22 is an enlarged view of a main part of FIG. 10;

FIG. 23 is a view taken along the line 23-23 in FIG. 22;

FIG. 24 is an operation explanatory view corresponding to FIG. 22;

FIG. 25 is a sectional view taken along line 25-25 of FIG. 10;

FIG. 26 is a sectional view taken along line 26-26 of FIG. 25;

FIG. 27 is an enlarged sectional view taken along line 27-27 of FIG. 5;

FIG. 28 is a view taken in the direction of arrow 28 in FIG. 27;

FIG. 29 is an enlarged sectional view taken along line 29-29 of FIG. 5;

FIG. 30 is an enlarged sectional view taken along line 30-30 of FIG. 5;

FIG. 31 shows a second embodiment of the change pedal shaft.

[Explanation of symbols]

Reference Signs List 9 casing 10 cylinder block 10 ₁ cooling fin 10 ₂ right side wall (side wall) 11 crankshaft 12 exhaust pipe 77 camshaft 80i push rod (valve operating mechanism) 80o push rod (valving mechanism) 101 main shaft (rotating shaft) 102 sub shaft (Rotating shaft) E Engine T Transmission

[Procedure amendment]

[Submission date] December 17, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0002

[Correction method] Change

[Correction contents]

[0002]

2. Description of the Related Art Such a power unit for a straddle-type vehicle has the following features.
For example, as disclosed in JP-A 7-1 9 5949 JP, are already known.

Claims (2)

[Claims] 1. A casing (9) for supporting a crankshaft (11) in the longitudinal direction of a vehicle body, and a cooling fin (10)
₁ ) An engine (E) is provided in which a cylinder block (10) formed upright is inclined to one of the left and right sides of the vehicle body, and an exhaust pipe (12) extending rearward from the front of the vehicle body to the cylinder block (10) side. the vehicle power unit disposed in close proximity to people, causes close to the side wall (10 ₂₎ of the tilt direction of the exhaust pipe (12) a cylinder block (10), the inclined direction side wall (10 ₂ ), Wherein a valve mechanism (80i, 80o) is housed in the power unit for a saddle-ride type vehicle. 2. A transmission that is disposed on the upper side of the casing (9) in the inclined direction and that rotates while being connected to a crankshaft (11), and that is rotated while being connected to the crankshaft (11). Rotation axis of (T) (101, 102)
The power unit for a straddle-type vehicle according to claim 1, wherein a power unit is disposed at a lower portion of the casing (9) in the inclined direction.