JP2001073888A - Air intake system for small vehicles - Google Patents

Abstract

(57) [Summary] In a small vehicle in which an engine, an air cleaner connected to the engine, and a tank are mounted on a body frame, suction of dust into the air cleaner is ensured while ensuring a sufficient intake air amount. Prevent as much as possible. A vehicle body frame and a vehicle body frame are provided.
Between the air cleaner 9 and the tank 101 stored in the inside.
A suction passage 104 leading to the unpurified chamber 99 in 6 is formed,
Air introduction ports 105 and 106 communicating with the suction passage 104 are provided in the vehicle body frame 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an intake device of an engine in a small vehicle in which an engine, an air cleaner connected to the engine, and a tank are mounted on a body frame.

[0002]

2. Description of the Related Art Conventionally, in a small vehicle disclosed in, for example, Japanese Patent Publication No. 5-72318, an intake port provided at one place of an air cleaner case in an air cleaner is directly opened to the outside.

[0003]

However, in order to secure a sufficient amount of intake air, the opening area of the intake port must be set to be sufficiently large. In a structure in which the suction port is directly opened to the outside, it becomes easier to suck dust into the air cleaner according to an increase in the opening area of the suction port.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides an intake device for a small vehicle which is capable of minimizing dust intake into an air cleaner while securing a sufficient intake air amount. With the goal.

[0005]

According to one aspect of the present invention, there is provided a small vehicle in which an engine, an air cleaner connected to the engine, and a tank are mounted on a body frame. An intake passage communicating with an unpurified chamber in the air cleaner is formed between the vehicle body frame and the tank housed in the vehicle body frame, and an air introduction port communicating with the intake passage is provided in the vehicle body frame. It is characterized by.

According to the first aspect of the present invention, an intake passage having a passage area sufficient to obtain a sufficient intake air amount is formed while narrowing the interval between the tank and the vehicle body frame. It is possible to minimize the intrusion of dust into the air cleaner by guiding the external air to the uncleaned chamber in the air cleaner through such a suction passage.

[0007] The invention according to claim 2 provides the above-described claim 1.
In addition to the configuration of the invention described in the above, the tank is a fuel tank, and according to this configuration, it is possible to cool intake air on the surface of the fuel tank and improve engine performance. Can be.

According to a third aspect of the present invention, in addition to the configuration of the first or second aspect, the air cleaner communicates with an air cleaner case formed by a part of the vehicle body frame and the suction passage. According to this structure, a non-cleaning chamber and a cleaning chamber connected to the engine are formed between the air cleaner case and the cleaner element housed in the air cleaner case. It is possible to easily configure the communication structure of the road with the unpurified chamber, and to reduce the number of parts by configuring the air cleaner case with a part of the body frame.

[0009]

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

1 to 11 show an embodiment of the present invention. FIG. 1 is a partially cutaway side view of a bicycle with an auxiliary engine, and FIG. 2 is a cross sectional view of the engine, and FIG. 2-2
3 is a sectional view taken along line 3-3 in FIG. 2, FIG. 4 is a sectional view taken along line 4-4 in FIG. 2, FIG. 5 is a right side view of the right holder member, and FIG. 7, FIG. 7 is a left side view of the left holder member, FIG. 8 is a view taken in the direction of arrow 8 in FIG. 7, FIG. 9 is an enlarged vertical sectional side view of FIG. 1, and FIG. Sectional view,
FIG. 11 is an enlarged view of a main part of FIG.

First, in FIG. 1, a body frame 15 of a bicycle with an auxiliary engine as a small vehicle has a head pipe 16 at a front end thereof, a down frame 17 extending rearward and downward from the head pipe 16, and a head pipe 16. A seat post 18 extending upward from a rear end upper portion of the down frame 17 and a cover 19 fastened to the upper portion of the down frame 17 are provided. The head pipe 16, the down frame 17 and the seat post 18 are integrally formed of an aluminum alloy or the like. Cast molded.

The head pipe 16 has a front fork 2
0 is steerably supported, the front wheel W _F is rotatably supported to the lower end of the front fork 20, steering handle 21 is provided at the upper end of the front fork 20. The left extended from the rear end of the down frame 17 to the rear, the rear wheel W _R is rotatably supported between the right pair of rear forks 22 ... rear end of the upper and lower seat post 18 direction intermediate portion and both rear fork 22 ... A pair of left and right stays 23 are provided between the rear ends of the stays.

The seat post 18 is formed in a cylindrical shape. A support pipe 24 is inserted into the seat post 18 from above, and is fixed to the seat post 18 so that the vertical position thereof can be adjusted. In addition, a saddle 25 on which the driver sits is mounted on the upper end of the support pipe 24.

At the rear of the down frame 17, a pedal shaft 26 is rotatably supported. At both ends of the pedal shaft 26, pedals 27 for a driver sitting on a saddle 25 to step on the down frame 17 are provided. It is fixed so that it is arranged on both sides. Moreover assisted state traveling direction forward toward the engine Bicycles, on the right side of the down frame 17 and the drive sprocket 28 is arranged coaxially with the pedal shaft 26, a driven sprocket 29 provided coaxially to the rear wheel W _R And the driving sprocket 2
8 and an endless chain 30 is wound.

Below the down frame 17 in the vehicle body frame 15, an engine 31 which exerts power for assisting the driver to depress the pedals 27 is provided.
It is provided so that a part of the down frame 17 is a component.

Referring to FIGS. 2, 3 and 4 together,
The cylinder block 32 of the engine 31 is arranged such that the axis of a cylinder bore 33 provided in the cylinder block 32 is substantially horizontal along the longitudinal direction of the bicycle. A cylinder head 34 arranged in front of the cylinder block 32 has Crankcase 3 coupled to cylinder block 32 and arranged behind cylinder block 32
5 is connected to the cylinder block 32.

A crankshaft 37 having an axis extending in the width direction of the bicycle is connected to a piston 36 slidably fitted in the cylinder bore 33 via a connecting rod 38. The crankcase 35 accommodating the crankshaft 37 includes an upper case 39 formed at a rear portion of the down frame 17 and a lower case 40 connected to each other via a holder 41. The division surface 44 of 40 is set in parallel with the axis of the cylinder bore 33 and the axis of the crankshaft 37.

The crankshaft 37 is a lower case 4 of the two cases 39 and 40 constituting the crankcase 35.
The crankshaft 3
7 is rotatably supported by a holder 41 composed of right and left holder members 42 and 43 sandwiching the crank pin 37a therebetween.

5 and 6, a right holder member 42 has a ring-shaped bearing portion 42a disposed on the front side (right side in FIGS. 5 and 6) and a rear side (left side in FIGS. 5 and 6). Side), a ring-shaped shaft support portion 42b, and a bearing portion 42a.
A connecting portion 42c for connecting between the shaft supporting portion 42b and an arm portion 42d extending downward from an intermediate portion of the connecting portion 42c;
A first connecting cylinder portion 42e extending from an upper portion of the connecting portion 42c on the bearing portion 42a side to the left holder member 43 side;
A second connecting cylinder 42f extending from the lower end to the left holder member 43 side, and a first, second, and first and second extending portions extending vertically by connecting an intermediate portion to a front portion and a rear portion of the bearing portion 42a and a rear portion of the shaft support portion 42b. Third fastening cylinder portions 42g, 42h, 42i
A fourth fastening cylinder 42j extending downward from a lower portion of the bearing portion 42a, fifth and sixth fastening cylinders 42k and 42m extending forward from an upper portion and a lower portion of the first fastening cylinder 42g,
It is integrally formed with a substantially L-shaped support arm 42n that protrudes outward from a rear portion of the bearing portion 42a and is bent forward, and is formed of, for example, an iron-based material such as FC300.

7 and 8, a left holder member 43 has a ring-shaped bearing 43a disposed on the front side (left side in FIGS. 7 and 8) and a rear side (right side in FIGS. 7 and 8). Side), a ring-shaped shaft support portion 43b disposed on the
A connecting portion 43c for connecting between the shaft supporting portion 43b and an arm 43d extending downward from an intermediate portion of the connecting portion 43c;
A first connecting cylinder portion 43e extending from the upper portion of the connecting portion 43c on the bearing portion 43a side to the right holder member 42 side;
A second connecting cylinder 43f extending from the lower end to the right holder member 42 side, and a first, second, and first and second extending portions extending vertically by connecting an intermediate portion to a front portion and a rear portion of the bearing portion 43a and a rear portion of the shaft support portion 43b. Third fastening cylinder portions 43g, 43h, 43i
And a fourth fastening cylinder portion 43j extending downward from a lower portion of the shaft support portion 43b, and fifth and sixth fastening cylinder portions 43k and 43m extending forward from upper and lower portions of the first fastening cylinder portion 43g. Then, it is formed of the same material as the left holder member 42 (for example, FC300).

The left and right holder members 42, 43
The first and second connecting cylinder portions 42e of the right holder member 42,
The first and second connecting cylinder portions 43e and 43 of the left holder member 43
f and screwed together to form a holder 41
Is configured.

The first to third fastening cylinders 42g of the holder 41,
43g; 42h. 43h; 42i, 43i, bolts 46, 46 ... are respectively inserted from below, and these bolts 46, 46 ... are screwed into the upper case 39, respectively. That is, the holder 41 is fastened to the upper case 39 of the crankcase 35.

The four stud bolts 47, 47... Arranged around the cylinder bore 33 are used to form the fifth and sixth fastening cylinder portions 42k, 43k, 42m, 43m of the holder 41.
Screwed into. Those stud bolts 47, 47 ...
Are inserted through the cylinder block 32 and the cylinder head 34, and nuts 48, 48... Are screwed into protruding portions of the stud bolts 47, 47. That is, the stud bolts 47, 47 and the nuts 48, 48 ...
The cylinder block 32 and the holder 41 are fastened together,
The upper case 39 of the crankcase 35 is connected to the cylinder block 32 via the holder 41.

Further, at a position away from the fastening position by the stud bolts 47, 47 and the nuts 48, 48,
The cylinder head 34 is fastened to the cylinder block 32 by one or more sets of bolts 49 and nuts 50.

Further, bolts 51,
51 are inserted in a liquid-tight manner from below, and their bolts 51,
51 is screwed into the fourth fastening cylinder portions 42j and 43j of the holder 41. That is, the lower case 40 that constitutes the crankcase 35 together with the lower case 39 is coupled to the upper case 39 via the holder 41. Moreover, a gasket 51 is interposed between the upper end of the lower case 40 and the upper case 39.

The crankshaft 37 is rotatably supported by bearings 42a, 43a of the holder 41 via ball bearings 53, 53. A generator 54 is arranged outside the left holder member 43 in the holder 41.
The rotor 55 of the generator 54 is fixed to one end of the crankshaft 37 protruding from the left holder member 43, and the stator 56 of the generator 54 is fixed to the bearing 43 a of the left holder member 43.

The engine 31 is of a so-called side valve type. A combustion chamber 61 facing a part of the top of a piston 36 is positioned rightward from the axis of the cylinder bore 33 in a posture facing forward in the front-rear direction of the bicycle. It is formed between the cylinder block 32 and the cylinder head 34 such that the center is located at a position shifted from the cylinder block 32. The cylinder head 34 has a spark plug 6 with an inner end facing the combustion chamber 61.
2 is attached.

An intake port 63 that can communicate with the combustion chamber 61 is provided above the cylinder block 32, and an exhaust port 64 that can communicate with the combustion chamber 61 is provided below the cylinder block 32.

An intake valve 65 for switching the communication between the intake port 63 and the combustion chamber 61 and an exhaust valve 66 for switching the communication between the exhaust port 64 and the combustion chamber 61 are provided.
It is supported by the cylinder block 32 so that it can be opened and closed, and is spring-biased in the valve closing direction.

The intake valve 65 and the exhaust valve 66 are
The valve mechanism 67 is driven to open and close by a timing drive gear 68 fixed to the crankshaft 37 and a spindle 69 fixed to the holder 41.
A timing driven gear 70 rotatably supported by the timing drive gear 68, a cam 71 formed integrally with the timing driven gear 70, and a cylinder block which swings following the cam 71. 32, an intake-side rocker arm 72 that is operatively connected to and linked to the intake valve 65, and that is supported by the cylinder block 32 so as to swing in accordance with the cam 71, and is also operatively associated with the exhaust valve 66. And an intake side rocker arm 73 connected thereto.

The timing drive gear 68 is formed of a material having substantially the same coefficient of thermal expansion as the material forming the holder 41. The bearing 42a and the support arm of the right holder member 42 of the holder 41 are provided. It is fixed to the crankshaft 37 at a position sandwiched between 42 m.
The support shaft 69 has an axis parallel to the crankshaft 37, and is fixed between the distal end of the support arm 42m and the bearing 42a. The timing driven gear 70 and the cam 71 are formed of a material having a coefficient of thermal expansion substantially equal to that of the material forming the holder 41, and are rotatably supported by the support shaft 69. Thus, the timing drive gear 68 reduces the rotational power of the crankshaft 37 by half and transmits it to the timing driven gear 70 and the cam 71. That is, the cam 71
The rotation of the crankshaft 37 is reduced to half of the rotation speed.

The upper end of the cylinder block 32 is connected to the downstream end of an intake pipe 74 communicating with the intake port 63.
The upstream end of the intake pipe 74 is connected to the downstream end of a carburetor 75 that is arranged above the engine 31 so as to partially house the down frame 17 in the body frame 15.

Referring to FIGS. 9 and 10, the down frame 17 of the body frame 15 is formed to have a substantially U-shaped cross-sectional shape with an open upper portion. The cover 19 is fastened to the down frame 17 so as to close the upper open end.

On the down frame 17, a first partition wall 76 is disposed in front of the vaporizer 75, a second partition wall 77 is disposed above the vaporizer 75, and disposed on the rear side of the vaporizer 75. The third partition 78 is integrally provided so as to partition the inside of the down frame 15 into four in the front-rear direction, and the center of the second partition 77 is cut out so as to form an opening 79.

The down frame 17 is connected to a first boss 80 projecting upward from a widthwise center bottom at a front portion in the down frame 17 and a front portion at a width center of the first partition wall 76. Second boss 81 extending vertically
And a third boss 82 extending vertically up to the rear of the third partition 78 at the center in the width direction.

On the other hand, the cover 19 is integrally provided with three bottomed cylindrical connecting cylinder portions 83, 84, 85 in which the lower end closing portions are opposed to the upper ends of the first to third boss portions 80 to 82. The cover 19 is fastened to the down frame 17 by screwing the screw members 86 to be inserted into the connecting cylinder portions 83 to 85 into the respective boss portions 80 to 82.

The cover 19 has a down frame 17.
4th partition 87 which contacts the upper end of 2nd partition 77 in
And a fifth partition 88 abutting on the upper end of the third partition 78 of the down frame 17 are integrally provided. Between the down frame 17 and the cover 19 in the fastened state, the first partition 76 has a rear end face. Tank storage room 89,
Inlet chamber 9 having second and fourth partition walls 77 and 87 as front end faces and third and fifth partition walls 78 and 88 as rear end faces.
0 and a storage chamber 91 having the third and fifth partition walls 78 and 88 as front end surfaces.

A seal member 92 is interposed between the cover 19 and the down frame 17 at a portion corresponding to the intake chamber 90, and the seal between the intake chamber 90 and the storage chamber 91 is sealed by the seal member 92.

The storage chamber 91 stores electrical components (not shown) such as an ignition device for igniting the ignition plug 62 and a control unit for controlling the operation of the engine 31. The intake chamber 90 is connected to a carburetor 75, and an inlet of the carburetor 75 is connected to a connection port 93 provided at the bottom of the down frame 17 so as to be continuous with the intake chamber 90.

Between the tank storage chamber 89 and the suction chamber 90,
The cover 19 and the down frame 17 constitute an air cleaner case 94, and an air cleaner 96 is formed by housing a cleaner elent 95 in the air cleaner case 94.

The cleaner element 95 is inserted into the down frame 17 between the first and second partition walls 76 and 77. The down frame 17 integrally includes a plurality of receiving portions 97 for receiving the cleaner element 95. The cover 19 is provided integrally with a plurality of pressing portions 98 for holding the cleaner element 95 between the receiving portions 97 and the like. With the cleaner element 95 sandwiched between the receiving portion 97 and the pressing portion 98, an unpurified chamber 99 is formed between the cover 19 and the cleaner element 95, and between the down frame 17 and the cleaner element 95. Is a purification chamber 100, and the purification chamber 1
00 communicates with the intake chamber 90 through the opening 79.

The fuel tank 101 is housed in the tank housing chamber 89. The fuel tank 101 is sandwiched between the plurality of projections 102 provided on the cover 19 and the down frame 17. . A fuel injection pipe 101a provided in the fuel tank 101 protrudes upward through the cover 19, and a cap 103 is detachably attached to an upper end of the fuel injection pipe 101a.

The first partition wall 7 is provided between the inner surface of the down frame 17 and the cover 19 and the outer surface of the fuel tank 101.
A suction passage 104 is formed between the cover 6 and the cover 19 and communicates with the uncleaned chamber 99 of the air cleaner 96. The cover 19 is provided with an air inlet 105 surrounding the fuel injection pipe 101 a so as to communicate with the suction passage 104. . FIG.
As shown in the figure, an air inlet 106 may be provided at the bottom of the down frame 17 at a portion corresponding to the tank storage chamber 89. In this case, the air inlet 106 is provided between the bottom surface of the fuel tank 101 and the down frame 17. A groove 101b is provided on the bottom surface of the fuel tank 101 in order to form the suction passage 104 connected to 106.

The fuel outlet pipe 107 extending downward from the lower part of the fuel tank 101 and the fuel outlet pipe 108 extending downward from the lowermost part of the fuel tank 101 are connected to the down frame 17.
The fuel hoses 109 and 108 have one ends connected to the fuel outlet pipes 107 and 108, respectively.
The other end of 110 is connected to cock 111 of vaporizer 75. Thus, the cock 111 guides the fuel from the fuel outlet pipe 107 to the carburetor 75, the state of guiding the fuel from the fuel outlet pipe 108 to the carburetor 75,
It is possible to switch between a state in which the fuel from any of 108 is not guided to the carburetor 75.

Referring again to FIGS. 3 and 4, an exhaust pipe 1 communicating with an exhaust port 64 is provided below the cylinder block 32.
The exhaust pipe 115 extends rearward below the engine 31 and extends rearward.
An exhaust muffler 116 disposed between the first and the rear wheel W _R
(See FIG. 1).

In FIG. 11, a clutch shaft 117 having an axis parallel to the crankshaft 37 is rotatably supported on shaft support portions 42b and 43b of the holder 41, and a pedal having an axis parallel to the clutch shaft 117. One end of the shaft 26 is rotatably supported via a ball bearing 118 on a left side wall of the upper case 39 of the crankcase 35 along the longitudinal direction of the bicycle. A pedal shaft 26 is provided on the right side wall of the upper case 39 along the longitudinal direction of the bicycle.
The outer end side of the rotary cylinder shaft 119 coaxially surrounding the other end side of
The rotary cylinder shaft 119 is rotatably supported via a ball bearing 120.
The roller bearing 1 is rotatably supported by the roller shaft 1 between the outer end side of the rotary cylinder shaft 119 and the pedal shaft 26.
21 are interposed. That is, the coaxial pedal shaft 26 and the rotary cylinder shaft 119 are supported by the upper case 39 of the crankcase 35 so as to enable relative rotation.
The drive sprocket 28 is fixed to the outer end of the rotary cylinder shaft 119.

A primary drive gear 122 is fixed to the crankshaft 37, and a primary driven gear 123 meshing with the primary drive gear 122
Are rotatably supported on the clutch shaft 117. Moreover, the primary drive gear 122 and the primary driven gear 123 are formed of a material having a coefficient of thermal expansion substantially equal to that of the material forming the holder 41.

The input member 12 which cannot rotate relative to the clutch shaft 117 is attached to the clutch shaft 117.
A start clutch 124 having an output gear 125 capable of rotating relative to the clutch shaft 117 is mounted. The primary driven gear 123 is connected to the input member a via a damper 144. The starting clutch 124 is connected to the crankshaft 37.
As the rotational speed of the input member 124a driven via the primary drive gear 122, the primary driven gear 123, and the damper 144 becomes equal to or higher than the set value,
Power is transmitted from the input member 124a to the output gear 125.

The output gear 125 of the starting clutch 124
Is connected to the rotary cylinder shaft 11 via the first planetary gear type reducer 126.
9. The carrier 127 of the first planetary gear type reducer 126 is mounted on the rotary cylinder shaft 119 so as not to rotate relatively,
The sun gear 128 is meshed with the output gear 125, and the ring gear 129 is engaged with the clutch shaft 117 so as to prevent the rotation about the axis of the rotary cylinder shaft 119.

A second planetary gear type reducer 130 opposed to the first planetary gear type reducer 126 at an interval is mounted on the pedal shaft 26, and a carrier 131 in the second planetary gear type reducer 130 is provided. Are engaged with the upper case 39 so as not to rotate about the axis of the pedal shaft 26, and the ring gear 132 is
The sun gear 133 is supported by a ring gear 132 so as to be rotatable around the axis.

The first and second planetary gear type reducers 126,
Between the pedals 130, a shifter 134 coaxial with the pedal shaft 26 is mounted on the pedal shaft 26 via a helical gear. The outer periphery of the shifter 134 is A spring 135, which is prevented from rotating around, is frictionally engaged. Thus, when the pedal shaft 26 rotates in the forward direction of the bicycle, the shifter 134 in a state where the rotation is prevented by the frictional engagement with the spring 135 moves to the first planetary gear type speed reducer 126 side, and When the pedal shaft 26 rotates in the backward direction of the bicycle, the shifter 13 is in a state where the rotation is prevented by frictional engagement with the spring 135.
4 moves to the second planetary gear type speed reducer 130 side. In addition, the shifter 134 enables the carrier 127 of the first planetary gear type speed reducer 126 to transmit power from the shifter 134 to the carrier 127, but the carrier 127
Ratchet engagement so as to disable power transmission to the ring gear 132 of the second planetary gear type speed reducer 130 from the ring gear 132 to the shifter 134 although power can be transmitted from the shifter 134 to the ring gear 132. The ratcheting engagement can be performed by disabling the power transmission.

Therefore, when the pedal shaft 26 is driven to rotate in the forward direction of the bicycle by depressing the pedals 27, the shifter 134 moves until the carrier 127 of the first planetary gear type reduction gear 126 is ratchet-engaged.
By applying rotational power to the pedal shaft 26 that exceeds the rotational resistance acting on the shifter 134 by frictional engagement with the pedal 5, rotational power is transmitted from the pedal shaft 26 to the rotary cylinder shaft 119 via the shifter 134 and the carrier 127. Can be transmitted.

On the other hand, the clutch shaft 117 has the second
A helical gear 136 meshing with the outer circumference of the sun gear 133 in the planetary gear type speed reducer 130 is rotatably supported,
The helical gear 136 is frictionally engaged with a spring 137 that is prevented from rotating around the axis of the clutch shaft 117 by engagement with the lower case 40. In addition, a rotating member 138 that faces the helical gear 136 with a space therebetween is attached to the clutch shaft 117 such that relative rotation is disabled.

When the pedal shaft 26 is rotationally driven in the backward direction of the bicycle by depressing the pedals 27, the shifter 134 moves until the ring gear 133 of the second planetary gear type speed reducer 130 is ratchet-engaged. By applying rotational power to the pedal shaft 26 that exceeds rotational resistance acting on the shifter 134 by frictional engagement with the helical gear 1 from the pedal shaft 26 via the shifter 134 and the second planetary gear type reducer 130.
The rotation power is transmitted to 36. Thereby, the spring 137
The helical gear 136 in a state where the rotation is prevented by frictional engagement with the helical gear 136 moves to the rotating member 138 side. In addition, the helical gear 136 is capable of transmitting power from the helical gear 136 to the rotating member 138.
It is possible to ratchet engage the rotating member 138 such that power transmission from the helical gear 136 to the helical gear 136 is disabled.

Therefore, the helical gear 1 is rotated by driving the pedal shaft 26 in the backward direction of the bicycle.
36 is moved to the ratchet engagement with the rotating member 138, and the helical gear 13 is moved by frictional engagement with the spring 137.
6 to the pedal shaft 26 by applying a rotational power exceeding the rotational resistance force acting on the pedal shaft 26.
Thus, rotational power can be transmitted to the clutch shaft 117 via the shifter 134, the second planetary gear type speed reducer 130, the helical gear 136, and the rotating member 138. In addition, the rotational power of the clutch shaft 117 is transmitted to the crankshaft 37 via the input member 124a of the starting clutch 124, the damper 144, the primary driven gear 123, and the primary drive gear 122, so that the engine 31 starts.

The opening at the lower end of the seat post 18 is closed by a breather cap 139 provided with a breather pipe 141.
5 is sandwiched between the upper case 39 and a holding plate 140 fastened to the upper case 39 which is a component. Moreover, between the breather cap 139 and the holding plate 140,
A maze 142 is formed to allow one end to communicate with the crankcase 35 and the other end to communicate with the breather pipe 141. Breather gas generated in the crankcase 35 separates entrained oil while passing through the maze 142. While being guided to the breather tube 141. Moreover, the hose 143 connected to the breather pipe 141 is
The first through third partitions 78 are airtightly penetrated, and extend from the opening 79 to the purification chamber 100 of the air cleaner 96 via the intake chamber 90.

Next, the operation of this embodiment will be described. The crankshaft 37 to which the timing driving gear 68 and the primary driving gear 122 are fixed, and the timing driven gear 7 meshing with the driving gears 68 and 122 are described.
0 and the primary driven gear 123
, So that each drive gear 68, 122
In addition, the accuracy between the shafts between the driven gears 70 and 123 can be easily improved. Moreover, since the holder 41 is formed of a material having substantially the same coefficient of thermal expansion as the material forming the drive gears 68, 122 and the driven gears 70, 123, the accuracy between the shafts can be improved even when the engine 31 is hot. It is possible to maintain the accuracy between the shafts and suppress generation of gear noise regardless of whether the engine 31 is cold or hot. Also, the crankshaft 3 is attached to the holder 41.
Since the holder 41 may be fastened to the crankcase 35 in a state where the gear 7 and the driven gears 70 and 123 are assembled, assembly and maintenance can be performed while maintaining the accuracy between the shafts. Can be improved.

Since the timing drive gear 68 and the timing driven gear 70 integrally having the cam 71 among the valve operating mechanisms 67 for driving the intake valve 65 and the exhaust valve 66 are supported by the holder 41, the intake valve 65 And exhaust valve 66
When adjusting the valve clearance of the cylinder block 32,
Further, it is not necessary to disassemble the cylinder head 34, and the adjustment of the valve clearance can be easily performed.

Since the holder 41 is fastened to the cylinder block 32 and the crankcase 35 is connected to the cylinder block 32 via the holder 41, combustion noise and crank noise are not directly transmitted to the crankcase 35. In this way, it is possible to contribute to noise prevention, and after assembling the holder 41 to one of the cylinder block 32 and the crankcase 35, the other of the cylinder block 32 and the crankcase 35 is attached to the holder 41.
Therefore, it is possible to improve the assemblability and maintainability while maintaining the accuracy between the shafts between the driving gears 68, 122 and the driven gears 70, 123.

Further, the crankcase 35 includes a holder 41
And the lower case 40 fastened to the holder 41, so that the upper case 39
And the holder 41 are fastened to each other.
The lower case 40 is fastened to the crankcase 35
And the driving gears 68, 122
In addition, the crankcase 35 can be assembled and maintained while maintaining the accuracy between the driven gears 70 and 123 between the shafts, so that the assemblability and maintainability can be improved.

A fuel tank 101 is accommodated in a tank accommodating chamber 89 composed of the down frame 17 and the cover 19, which are constituent elements of the body frame 15, and the fuel tank 101 is interposed between the down frame 17 and the cover 19. The formed suction passage 104 communicates with the unpurified chamber 99 in the air cleaner 96, and the cover 19 and the down frame 127 are provided with air introduction ports 105, 105. Therefore, it is possible to form the intake passage 104 having a passage area sufficient to obtain a sufficient intake air amount while narrowing the space between the fuel tank 101 and the down frame 17 and the cover 19. By guiding the external air to the unpurified chamber 99 in the air cleaner 96 through the appropriate suction passage 104, it is possible to prevent dust from entering the air cleaner 96 as much as possible.

Moreover, the intake air can be cooled on the surface of the fuel tank 101, and the engine performance can be improved.

Further, the air cleaner 96 includes the down frame 17 and the cover 19 which are a part of the body frame 15.
An air cleaner case 94 composed of
And a cleaner element 95 housed in the air cleaner case 94 by forming an unpurified chamber 99 leading to the air cleaner case 100 and a purifying chamber 100 connected to the engine 31 between the air cleaner case 94 and the suction passage. 1
The structure of the air cleaner case 9 with a part of the body frame 15 can be easily configured so that the communication structure with the unpurified chamber 99 of the air cleaner 04 can be easily configured.
4, the number of parts can be reduced.

Although the embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the present invention described in the appended claims. It is possible to do.

[0065]

As described above, according to the first aspect of the present invention, a suction passage having a passage area sufficient to obtain a sufficient intake air amount is formed while reducing the distance between the tank and the body frame. By directing the external air through such a suction passage to the unpurified chamber in the air cleaner,
Dust can be prevented from entering the air cleaner as much as possible.

According to the second aspect of the present invention, the intake air can be cooled on the surface of the fuel tank, and the engine performance can be improved.

Further, according to the third aspect of the present invention, the structure for communicating the suction passage to the unpurified chamber can be easily configured.
The number of parts can be reduced by configuring the air cleaner case with a part of the body frame.

[Brief description of the drawings]

FIG. 1 is a partially cutaway side view of a bicycle with an auxiliary engine.

FIG. 2 is a cross-sectional view of the engine, taken along line 2-2 of FIG. 4;

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

FIG. 4 is a sectional view taken along line 4-4 of FIG. 2;

FIG. 5 is a right side view of the right holder member.

6 is a view taken in the direction of arrow 6 in FIG. 5;

FIG. 7 is a left side view of the left holder member.

8 is a view taken in the direction of arrow 8 in FIG. 7;

FIG. 9 is an enlarged vertical sectional side view of a main part of FIG. 1;

FIG. 10 is an enlarged sectional view taken along line 10-10 of FIG. 9;

FIG. 11 is an enlarged view of a main part of FIG. 2;

[Explanation of symbols]

 15 Body frame 31 Engine 94 Air cleaner case 95 Cleaner element 96 Air cleaner 99 Unpurified chamber 100 Purified chamber 101 Fuel tank 104・ Suction path 105,106 ・ ・ ・ Air inlet

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B62M 23/02 B62M 23/02 B F02M 35/16 F02M 35/16 N 37/00 301 37/00 301D

Claims (3)

[Claims] An engine (31) and said engine (3)
1) an air cleaner (96) connected to the tank (1);
01) is mounted on the body frame (15), the air cleaner (96) is provided between the body frame (15) and the tank (101) housed in the body frame (15). A suction passage (104) leading to the unpurified chamber (99) is formed in the vehicle body frame (1).
5) an air inlet (1) leading to the suction passage (104);
05, 106) are provided. 2. The intake system according to claim 1, wherein the tank is a fuel tank. 3. The air cleaner (96) includes an air cleaner case (94) formed as a part of the vehicle body frame (15), an uncleaned chamber (99) communicating with the suction passage (104), and the engine ( A purifying chamber (100) connected to the air cleaner case (94) is formed between the air cleaner case (94) and the cleaner element (95) housed in the air cleaner case (94). The air intake device for a small vehicle according to claim 1.