WO2005007495A1

WO2005007495A1 - Engine for saddle-riding type vehicle and saddle-riding type vehicle having the same

Info

Publication number: WO2005007495A1
Application number: PCT/JP2004/008883
Authority: WO
Inventors: Tatsuya Masuda; Yousuke Ishida
Original assignee: Yamaha Hatsudoki Kabushiki Kaisha
Priority date: 2003-07-16
Filing date: 2004-06-24
Publication date: 2005-01-27
Also published as: JP2006347187A

Abstract

An engine for a saddle-riding type vehicle, wherein a V-belt type continuously variable transmission (16) having a primary sheave (55) and a secondary sheave (56) is disposed on the right side of an engine body. The secondary sheave (56) is disposed on the upper side of the primary sheave (55). A secondary sheave shaft (47) is disposed on the upper side of a drive shaft (48). Induction system parts (154) are disposed on the left upper side of the engine body. An air cleaner (154C) as a part of the induction system parts (154) is overlapped with the secondary sheave (56) in side view.

Description

Specification

Saddle-ride type vehicle engine and saddle-ride type vehicle provided with the same

Technical field

The present invention relates to a straddle-type vehicle engine and a straddle-type vehicle provided with the same.

Background art

[0002] Saddle-riding vehicles are widely used, for example, as motorcycles. Normally, motorcycles and the like include a Lear arm for supporting a rear wheel, and a Lear arm bracket for supporting the Lear arm to a vehicle body. A pivot shaft for supporting the Lear arm is provided on the Lear arm bracket, and the Lear arm is supported so as to be vertically swingable about the pivot shaft.

[0003] In the engine mounted on such a straddle-type vehicle, it is necessary to consider the positional relationship between the engine and the pivot shaft when deciding the layout of each component constituting the engine. The engine is also provided with an automatic transmission, intake system components, and the like, which are formed only by the engine body including cylinders and pistons. Therefore, the layout of the entire engine, including these intake system components, is important.

[0004] Japanese Patent Laying-Open No. 11-129971 (hereinafter referred to as Patent Document 1) discloses the following layout for intake system components and an automatic transmission.

[0005] That is, in the engine disclosed in Patent Document 1, the cylinder is attached to the crankcase in a posture inclined forward, and the axial direction of the cylinder extends substantially in the front-rear direction of the vehicle body. An intake pipe is connected to an upper part of the cylinder head. The intake pipe extends rearward, and a carburetor is connected to the rear end of the intake pipe. An air cleaner is connected to the rear side of the carburetor. The air cleaner is disposed between the front of the sheet and the crankcase with respect to the vertical position. A storage box for storing a helmet and the like is provided below the seat, and an air cleaner is disposed in front of the storage box. A downwardly open concave portion is formed below the front portion of the seat, and the upper portion of the air cleaner enters into the concave portion.

[0006] The engine includes a V-belt type automatic transmission. This automatic transmission A primary sheave (drive pulley) connected to the right end of the shaft, a secondary sheave (driven pulley), and a V-benolet wound around the primary sheave and the secondary sheave. The automatic transmission is housed in a space (transmission room) defined by a right side wall of the crankcase and a transmission cover attached to the outside (right side) of the side wall. A connection shaft extending in the vehicle width direction (left-right direction) is connected to the shaft center portion of the secondary sheave. A centrifugal clutch is provided on the left side of the engine, and a secondary sheave is connected to the input member of the centrifugal clutch via the connection shaft. The rotation of the centrifugal clutch is input to the drive shaft via the speed reduction mechanism.

Patent Document 1: Japanese Patent Application Laid-Open No. H11-129997

Disclosure of the invention

Problems to be solved by the invention

[0008] In the above-described engine, an intake system component including an intake pipe, a carburetor, and the like is disposed above the engine. The V-belt type automatic transmission was located below the engine to avoid the intake system components. Therefore, in the above-mentioned engine, it was necessary to secure an installation space for the V-belt type automatic transmission in the lower part of the engine, and it was difficult to freely set the layout around the drive shaft. In other words, the degree of freedom in the layout of the engine, especially around the drive axis, was low.

[0009] The present invention has been made in view of its power, and an object of the present invention is to improve the layout of the intake system components and the transmission in a straddle-type vehicle engine. Another object of the present invention is to increase the degree of freedom of the layout of the engine or the entire saddle type vehicle. Another object of the present invention is to increase the degree of freedom of layout around a drive axis in a saddle type vehicle. Another object of the present invention is to provide a suitable saddle-ride type vehicle equipped with the saddle-ride type vehicle engine.

Means for solving the problem

[0010] A straddle-type vehicle engine according to the present invention includes an engine body having a crankshaft and an intake port extending in the left-right direction, a primary sheave rotating according to rotation of the crankshaft, and a secondary sheave extending in the left-right direction. A secondary sheave having a shaft, and a transmission belt wound around the primary sheave and the secondary sheave. And an intake system component connected to an intake port of the engine main body, wherein at least a part of the intake system component is the secondary system in a side view. It overlaps the sheave.

As described above, in the saddle-ride type vehicle engine, at least a part of the intake system components is

, So as to overlap with the secondary sheave in side view. As a result, at least a part of the intake system components and the secondary sheave are located on the same side (for example, the upper side) with respect to the engine body in a side view, and are arranged side by side with each other. As a result, extra space is generated in the engine as much as the position of the secondary sheave approaches the intake system components. Therefore, the degree of freedom in the rate of the engine or the entire saddle-ride type vehicle is increased.

[0012] The transmission is arranged on one of the left and right sides of the engine body, the secondary sheave is arranged above the primary sheave, and the intake system component is arranged above the engine body. It is preferable that the transmission is provided in the left-right direction, and is disposed on the side opposite to the side where the transmission is located.

As described above, since the secondary sheave is arranged above the primary sheave and the intake system components are arranged above the engine main body, an extra space is generated below the engine main body. Therefore, the degree of freedom in layout below the engine body increases. In the left-right direction, the intake system components are located on the side opposite to the side where the transmission is installed, so that interference between the intake system components and the transmission can be effectively avoided, and an efficient layout is achieved. Is realized.

[0014] The saddle-ride type vehicle engine includes a transmission case accommodating the primary sheave, the secondary sheave, and the transmission belt; a drive shaft directly or indirectly connected to the secondary sheave shaft; The secondary sheave shaft is further disposed above the drive shaft, the intake system component is disposed above the engine body, and at least a part of the intake system component is viewed from a side. Preferably, the transmission case is disposed inside the contour of the transmission case.

[0015] Here, since the secondary sheave shaft may be indirectly connected to the drive shaft, a speed reduction mechanism or the like may be interposed between the secondary sheave shaft and the drive shaft. Of course.

[0016] In the saddle-ride type vehicle engine, the secondary sheave shaft is separate from the drive shaft, and is disposed above the drive shaft. Therefore, there is no restriction on the secondary sheave axis, and the degree of freedom in layout around the drive axis increases. As a result, for example, the drive shaft can be brought closer to the pivot shaft.

[0017] Preferably, the straddle-type vehicle engine includes a kick starter shaft disposed below the secondary sheave.

As a result, the layout of the engine can be optimized.

A straddle-type vehicle according to the present invention includes the saddle-ride type vehicle engine.

[0020] The straddle-type vehicle includes a vehicle main body that supports the saddle-ride type vehicle engine in a posture such that the drive shaft is positioned rearward of the crankshaft; A rear arm that is supported and supports a rear wheel; and a transmission member that transmits a driving force from the drive shaft to the rear wheel. A support point of the rear arm in the vehicle body is the saddle-ride type vehicle in a side view. Is preferably located behind the engine.

[0021] It is preferable that a support point of the rear arm in the vehicle body is located below an axis of the secondary sheave shaft.

[0022] Further, it is preferable that a support point of the lear arm in the vehicle body is located near the rear of the drive shaft.

[0023] This makes it possible to suppress a decrease in the transmission efficiency of the driving force of the transmission member when the rear arm swings around the support point.

The invention's effect

[0024] As described above, according to the present invention, at least a part of the intake system components is arranged so as to overlap with the secondary sheave of the transmission in side view. Therefore, an extra space in the layout can be generated as much as the position of the secondary sheave is closer to the intake system components, and the degree of freedom in the layout of the engine or the entire saddle-ride type vehicle can be increased.

Brief Description of Drawings

FIG. 1 is a left side view of a motorcycle according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the engine unit taken along line II-II of FIG. FIG. 3 is a partial sectional view of an engine unit.

Garden 4] is a right side view showing the arrangement of each rotating shaft of the engine.

FIG. 5 is a perspective view of a main part of the engine as viewed obliquely from the upper front left. Garden 6] is a sectional view of the engine as viewed from the rear side.

FIG. 7 is a left side view schematically showing a main part of the engine.

Explanation of symbols

1 Motorcycle (Saddle-type vehicle)

2 Engine unit

7 Rear wheel

8 Lear arm

15 Engine body

16 V belt type continuously variable transmission (transmission)

17 distant clutch

28 Crank wheel

45 Transmission case (transmission case)

47 Secondary sheave shaft

48 drive shaft

50 Chain (transmission member)

55 Primary Sheave

56 Secondary sheave

57 V Benoleto (Transmission Benoleto)

100 pivot axis (support point)

150 kick starter shaft

154 Intake system parts

154C air cleaner

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a motorcycle 1 equipped with an engine according to the present embodiment. As will be described later in detail, the engine according to the present embodiment is an engine with a continuously variable transmission. A head pipe 3 is fixed to the front end of the body frame la. A front fork 5 is supported on the head pipe 3 so as to be rotatable in the left-right direction. A front wheel 4 is rotatably supported at the lower end of the front fork 5.

[0029] A rear arm bracket 6 is disposed at the center in the front-rear direction of the vehicle body. The Lear arm 8 is supported on the Lear arm bracket 6 via a pivot shaft (support point) 100. The rear arm 8 is rotatably supported by a pivot shaft 100. Therefore, the rear arm 8 is provided so as to be vertically swingable about the pivot shaft 100. A rear wheel 7 is rotatably supported at the rear end of the rear arm 8. A seat 9 is disposed above the body frame la. The seat 9 includes a driver seat 9a and a rear passenger seat 9b. Although details will be described later, the engine unit 2 is attached to the vehicle body frame la in such a manner that a drive shaft 48 (see FIG. 4) for outputting a rotational driving force is located behind the crankshaft 28. In this engine unit 2, the pivot shaft 100 of the rear arm 8 is located behind the engine unit 2 and is located near the rear of the drive shaft 48.

[0030] As shown in Fig. 1, the vehicle body frame la includes a down tube lb extending obliquely downward and rearward from the head pipe 3, an upper tube lc extending obliquely upward following the rear end of the down tube lb, and a down tube lb. And the upper tube lc, and a seat rail Id extended in the front-rear direction between the down tube lb and the upper tube lc. The down tube lb, the upper tube lc, and the seat rail 1d are provided on each of the left and right sides of the vehicle body.

The vehicle body frame la is covered with a resin cover 10. The cover 10 includes a front cover 10a, a resinino red 10b, a side cover 10c, and the like. A steering handle 11 covered with a handle cover 11a is fixed to an upper end of the front fork 5. A lya cushion (shock absorber) 12 is provided between the lear arm 8 and the lear arm bracket 6.

[0032] The engine unit 2 is suspended from the down tube lb of the body frame la. Supported by. The engine unit 2 has an air-cooled 4-cycle single-cylinder engine as the engine body 15 (see Fig. 2), and the cylinder axis A of the engine body 15 is inclined at about 45 degrees from the horizontal axis.

Next, the configuration of the engine unit 2 will be described in detail with reference to FIGS. FIG. 2 is a sectional view taken along the line II-II in FIG. Fig. 3 is a detailed enlarged view of Fig. 2, showing the vicinity of the crankcase. FIG. 4 is a diagram showing a layout of each shaft in the engine unit 2, and shows a layout when the vehicle body is viewed from the right side direction (that is, from the crank shaft direction).

As shown in FIG. 2, the engine unit 2 includes an engine body 15, a V-belt type continuously variable transmission device 16, a wet multi-plate centrifugal clutch 17, and a reduction mechanism 18.

The engine body 15 includes a cylinder block 19, a cylinder head 20, and a crankcase 22. The cylinder head 20 is connected to the upper mating surface of the cylinder block 19. A head cover 21 is provided above the cylinder head 20. The crankcase 22 is connected to a lower mating surface of the cylinder block 19. The crankcase 22 supports and supports a crankshaft 28 and a secondary sheave shaft (transmission shaft) 47.

[0036] On the rear surface of the cylinder head 20, an intake port (not shown) communicating with the combustion recess 20a is opened. The intake port is connected to a carburetor 23 via an intake pipe 23a (see FIG. 1). On the other hand, an exhaust port (not shown) communicating with the combustion recess 20a is opened on the front surface of the cylinder head 20. An exhaust pipe 24 (see FIG. 1) is connected to this exhaust port. As shown in FIG. 1, the exhaust pipe 24 extends obliquely rearward and downward, and then extends obliquely rearward upward through the right side of the engine body 15 and is connected to a muffler 25. The muffler 25 is provided on the right side of the rear wheel 7. As shown in FIG. 2, a spark plug 30 is inserted inside the combustion recess 20a.

[0037] On the left side of the cylinder block 19, a chain chamber 19a that connects the inside of the crankcase 22 and the inside of the cylinder head 20 is formed. A timing chain 34 is provided in the chain room 19a. The timing chain 34 is wound around the crankshaft 28 and the camshaft 31. The camshaft 31 rotates according to the rotation of the crankshaft 28, and opens and closes an intake valve and an exhaust valve (not shown).

[0038] A piston 26 is slidably inserted into the cylinder bore of the cylinder block 19. . A small end 27b of a connecting rod 27 is connected to the piston 26. A crank pin 29 is provided between the left crank arm 28a and the right crank arm 28b of the crank shaft 28. The large end 27a of the connecting rod 27 is connected to the crankpin 29. Reference numeral 32 indicates a cylinder sleeve.

[0039] The crankcase 22 includes two divided cases, that is, a first case 40 on the left and a second case 41 on the right. The mating surface between the first case 40 and the second case 41, that is, the split surface D of the crankcase 22 extends parallel to the axis L of the cylinder block 19. The split plane D does not coincide with the axis L and is offset to the left of the axis L

[0040] On the right side of the second case 41, a case cover 71 is attached. An opening is formed on the right side of the second case 41, and the case cover 71 covers the opening. The case cover 71 is detachably fixed to the second case 41 by bolts 72. Therefore, the case cover 71 is easy to attach and detach. By removing the case cover 71 from the second case 41, the centrifugal clutch 17 and the secondary sheave shaft 47 can be easily removed.

A generator case 44 for housing the generator 42 is detachably attached to the left front side of the first case 40. On the right side of the second case 41, a transmission case 45 accommodating the V-belt type continuously variable transmission 16 is attached. The V-belt type continuously variable transmission 16 is housed in a transmission room defined by a transmission case 45.

[0042] The transmission case 45 is formed independently of the crankcase 22, and includes a case body 45a and a lid 45b. The case body 45a is arranged on the right side of the second case 41, and is open on the right side. The lid 45b is disposed on the right side of the case main body 45a, and seals an opening on the right side of the case main body 45a. The case body 45a, the lid 45b, and the second case 41 are integrally fixed by bolts 70. A gap a is provided between the bottom wall 45c of the case body 45a and the second case 41. Since the case main body 45a and the second case 41 are separated from each other in this manner, transmission of heat from the engine main body 15 to the transmission case 45 is suppressed. Note that the right side of the transmission case 45 is covered with a decorative cover 60. On the front side (upper side in FIG. 2) of the crankcase 22, a crankshaft 28 is disposed so as to extend in the left-right direction. The left side of the center line of the crankshaft 28 with respect to the axis L of the cylinder block 19 is rotatably supported by the first case 40 via a bearing 35. On the other hand, the right side of the center line of the crankshaft 28 from the axis L is rotatably supported by the second case 41 via the bearing 36.

[0044] The right end of the crankshaft 28 extends into the transmission case 45 beyond the second case 41. A primary sheave (drive pulley) 55 of the V-belt type continuously variable transmission 16 is coaxially fitted to the right end of the crankshaft 28. Therefore, the primary sheave 55 rotates according to the rotation of the crankshaft 28. The right end of the crankshaft 28 forms a primary sheave shaft 55d. However, the mode of connection between the primary sheave 55 and the crankshaft 28 is not limited to the above mode. The primary sheave shaft 55d and the crankshaft 28 may be formed separately. The primary sheave shaft 55d may not necessarily be arranged coaxially with the crankshaft 28, but may be arranged parallel to the crankshaft 28, for example. In addition, the term "connection" as used herein means a connection in a broad sense, and includes not only a case where it is directly connected but also a case where it is indirectly connected, unless otherwise specified. Meaning.

On the other hand, the left end of the crankshaft 28 extends into the generator case 44 beyond the first case 40. Further, a generator 42 is attached to the left end of the crankshaft 28. A seal member 37 is provided between a portion of the right end surface of the second case 41 on which the crankshaft 28 extends and a bottom wall 45c of the transmission case 45. Thus, the second case 41 is sealed with respect to the transmission case 45. Therefore, a wet clutch can be used as the clutch housed in the second case 41. As described above, in this embodiment, the wet multi-plate centrifugal clutch 17 is used as the clutch.

The generator 42 includes a stator 42b and a rotor 42a facing the stator 42b.

The rotor 42a is fixed to a sleeve 43 that rotates together with the crankshaft 28. The sleeve 43 has a tapered portion of the crankshaft 28 fitted therein. The stator 42b is fixed to the generator case 44.

[0047] On the rear side (lower side in FIG. 2) of the crankcase 22, a secondary parallel to the crankshaft 28 is provided. One sheave shaft 47 is arranged. The right part of the center of the secondary sheave shaft 47 is supported by a case cover 71 via a bearing 38. The left portion of the central portion of the secondary sheave shaft 47 is supported by the left end of the second case 41 via a bearing 39. The right end of the secondary sheave shaft 47 extends into the transmission case 45 beyond the second case 41. The secondary sheave (driven pulley) 56 of the V-belt type continuously variable transmission 16 is connected to the right end of the secondary sheave shaft 47. Here, the secondary sheave 56 is coaxially connected to the secondary sheave shaft 47.

[0048] A centrifugal clutch 17 is attached to the left part of the secondary sheave shaft 47.

The centrifugal clutch 17 is disposed on the left side of the secondary sheave 56 of the V-belt type continuously variable transmission 16, that is, on the cylinder block 19 side. Such an arrangement is achieved by the large internal space of the second case 41. That is, in the engine unit 2, the division plane D of the crankcase 22 is located on the left side of the axis L of the cylinder block 19, and a wide space is secured inside the second case 41. Therefore, the eccentric clutch 17 can be arranged on the left side of the secondary sheave 56.

The centrifugal clutch 17 is a wet-type multi-plate centrifugal clutch, and includes an inner clutch 84 and a bowl-shaped outer clutch 83. The outer clutch 83 is spline-fitted to the secondary sheave shaft 47, and rotates together with the secondary sheave shaft 47, while freely moving in the axial direction of the secondary sheave shaft 47. The inner clutch 84 is disposed coaxially inside the outer clutch 83. The inner clutch 84 is spline-fitted to the small reduction gear 74 on the primary side, and the small reduction gear 74 rotates together with the inner clutch 84. The small reduction gear 74 is rotatably supported by the secondary sheave shaft 47.

As shown in FIG. 3, inside the outer clutch 83, a plurality of outer clutch plates 85 are arranged. Press plates 86 are arranged on both left and right ends of the outer clutch plate 85, respectively. The outer clutch plate 85 and the pressing plate 86 are locked to the outer clutch 83 so as to rotate together with the outer clutch 83. An inner clutch plate 87 is provided between the outer clutch plate 85 and the pressing plate 86. The inner clutch plate 87 is locked to the outer peripheral portion of the inner clutch 84 so as to rotate together with the inner clutch 84.

[0051] Inside the outer clutch 83, a cam surface 83a protruding leftward is formed. And A weight 88 is provided between the cam surface 83a and the right pressing plate 86. When the rotation speed of the outer clutch 83 becomes equal to or higher than a predetermined speed, the weight 88 receives the centrifugal force and moves radially outward. Since the cam surface 83a is formed inside the outer clutch 83, when the weight 88 moves outward in the radial direction, the right pressing plate 86 is pushed leftward by the weight 88 and moves leftward. As a result, the outer clutch plate 85 and the inner latch plate 87 are connected. That is, the clutch is connected. 2 and 3, the front part (upper side in FIGS. 2 and 3) of the centrifugal clutch 17 indicates the disconnected state, and the rear part (lower side in FIGS. 2 and 3) indicates the connected state. It represents.

The V-belt type continuously variable transmission 16 includes a primary sheave 55, a secondary sheave 56, and a V-belt 57 wound around the primary sheave 55 and the secondary sheave 56. As described above, the primary sheave 55 is attached to the right end of the crankshaft 28. Therefore, the driving force of the crankshaft 28 is transmitted to the primary sheave 55. The secondary sheave 56 is connected to the right end of the secondary sheave shaft 47.

[0053] The primary sheave 55 includes a fixed pulley half 55a and a movable pulley half 55b opposed to the fixed pulley half 55a. The fixed pulley half 55a is fixed to the right end of the crankshaft 28, and rotates together with the crankshaft 28. The movable pulley half 55b is disposed on the left side of the fixed pulley half 55a. A slide collar 59 slidable with respect to the crankshaft 28 is attached to the crankshaft 28. The movable pulley half 55b is attached to the crankshaft 28 via the slide collar 59. Therefore, the movable pulley half 55b rotates together with the crankshaft 28 and is movable in the axial direction of the crankshaft 28. A cam plate 58 is provided on the left side of the movable pulley half 55b. A cylindrical weight 61 is disposed between the cam plate 58 and the movable pulley half 55b.

The secondary sheave 56 includes a fixed pulley half 56a and a movable pulley half 56b facing the fixed pulley half 56a. The movable pulley half 56b is attached to the right end of the secondary sheave shaft 47. The movable pulley half 56b rotates together with the secondary sheave shaft 47 and is movable in the axial direction of the secondary sheave shaft 47. Secondary A coil spring 67 is provided at the right end of one sheave shaft 47, and the movable pulley half 56 b receives a leftward biasing force from the coil spring 67. The fixed pulley half 56a is installed on the left side of the movable pulley half 56b. A cylindrical slide collar 62 is fixed to the axis of the fixed pulley half 56a. The slide collar 62 is spline-fitted to the secondary sheave shaft 47.

[0055] In this V-belt type continuously variable transmission 16, the force of the weight 61 pushing the movable pulley half 55b on the drive side to the right and the force of the coil spring 67 pushing the movable pulley half 56b on the driven side back to the left. The reduction ratio is determined according to the magnitude relation of. That is, when the number of revolutions of the crankshaft 28 increases, the weight 61 moves radially outward (upward in FIG. 3) due to centrifugal force, and moves the movable pulley half 55b on the drive side to the right. Accordingly, the driven movable half pulley 56b also moves to the right against the urging force of the coil spring 67. As a result, the winding diameter of the V belt 57 on the driving pulley 55 increases, and the winding diameter of the driven pulley 56 decreases. Therefore, the reduction ratio becomes small. On the other hand, when the rotation speed of the crankshaft 28 decreases, the centrifugal force of the weight 61 decreases, so that the weight 61 moves radially inward. Therefore, the movable pulley half 55b on the driving side can easily move to the left. Then, the movable pulley half 56b on the driven side moves to the left under the biasing force of the coil spring 67, and accordingly, the movable pulley half 55b also moves to the left. As a result, the winding diameter of the V belt 57 on the driving pulley 55 decreases, and the winding diameter of the driven pulley 56 increases. Therefore, the reduction ratio increases.

A lock nut 66 is screwed into the tip of the secondary sheave shaft 47, and the secondary sheave 56 is fixed to the secondary sheave shaft 47 via the lock nut 66. The lock nut 66 is recessed in the right end 62a of the slide collar 62. The inner diameter of the slide collar 62 gradually increases in the axial direction. On the other hand, the right end 47a of the secondary sheave shaft 47 is gradually reduced. In other words, the diameter of the secondary sheave shaft 47 is reduced stepwise toward the distal end.

[0057] In the present engine unit 2, by adopting such a configuration, the lock nut 66 can be arranged without any trouble inside the right end portion 62a of the slide collar 62. Therefore, it is necessary to position the lock nut 66 on the left side of the spring receiving member 65 of the coil spring 67. It is possible. Thus, the protrusion on the outside (right side) without shortening the coil spring 67 itself can be reduced. In other words, the engine unit 2 is downsized (widthwise downsized) with a simple structure.

As shown in FIG. 2, the speed reduction mechanism 18 includes an idle shaft (deceleration shaft) 52 parallel to the secondary sheave shaft 47. The idler shaft 52 is connected with a large reduction gear 75 which is engaged with the primary small reduction gear 74. The small reduction gear 74 is rotatably mounted on the secondary sheave shaft 47. The idler shaft 52 is further integrally formed with a small secondary reduction gear 76. The drive shaft 48 is integrally formed with a large reduction gear 77 that meshes with the small reduction gear 76.

The right end of the idle shaft 52 is supported on the left side of the second case 41 via a bearing 91. The left end of the idle shaft 52 is rotatably supported by the left side of the first case 40.

[0060] The drive shaft 48 is provided in parallel with the idle shaft 52. The right end of the drive shaft 48 is supported by the left part of the second case 41 via a bearing 92. The left side of the drive shaft 48 is supported by the left side of the first case 40 via a bearing 93. A sprocket 49 is connected to the left end of the drive shaft 48. The sprocket 49 is connected to a driven sprocket 51 (see FIG. 1) of the rear wheel 7 via a chain 50.

Next, a layout of each rotating shaft in the engine unit 2 will be described with reference to FIG. FIG. 4 is a side view showing the arrangement of the rotating shafts when the vehicle body is viewed from the right side. The secondary sheave shaft 47 and the drive shaft 48 are configured as separate shafts. The secondary sheave shaft 47 is disposed above the drive shaft 48, and is disposed slightly forward of the drive shaft 48. The idler shaft 52 is disposed obliquely below and forward of an imaginary line connecting the axis of the drive shaft 48 and the axis of the secondary sheave shaft 47, that is, on the primary sheave 55 side. The secondary sheave shaft 47 is disposed above the primary sheave shaft 55d, and the secondary sheave 56 is provided entirely above the primary sheave 55.

[0062] The drive shaft 48 is located inside the outline (outline) of the transmission case 45 as viewed from the side of the vehicle body. In other words, the drive shaft 48 is It is arranged to fit within the feel. However, as long as most of the drive shaft 48 (for example, half or more of the drive shaft 48) is located inside the above-mentioned contour, the entire drive shaft 48 must be inside the above-mentioned contour. It does not have to be located.

FIG. 5 is a perspective view of a main part (hereinafter, referred to as an engine main part) 300 of the engine unit 2 and the transmission case 45 as viewed obliquely from the upper front left. In FIG. 5, the cylinder block 19 of the engine body 15 and the like (see FIG. 2) and an intake system component 154 (see FIG. 4) to be described later are omitted for convenience.

As shown in FIG. 5, the transmission case 45 is provided on the right side of the engine main part 300. As described above, since the secondary sheave 56 is disposed behind and above the primary sheave 55, the transmission case 45 is inclined rearward and obliquely upward.

[0065] Reference numeral 302 denotes a clutch chamber that houses the centrifugal clutch 17. The sprocket 49 into which the drive shaft 48 is fitted is located on the left side of the clutch chamber 302. The transmission case 45 and the clutch chamber 302 have a shorter width (that is, a length in the left-right direction) than the main engine part 300. Therefore, a relatively large spare space 304 is formed on the left side of the transmission case 45 and the clutch chamber 302. Therefore, in the present embodiment, the extra space 304 is effectively used as an installation space for the intake system component 154. That is, the intake system component 154 is arranged in the extra space 304 so as not to contact the transmission case 45 and the clutch chamber 302. Conversely, by arranging the intake system components 154 in the extra space 304, interference between the intake system components 154 and the transmission case 45 can be prevented, and the transmission case 45 is connected to the engine main part 300. It is possible to arrange above.

As shown in FIG. 4, an intake pipe 23a is connected to the cylinder head 20. The intake pipe 23a extends rearward through the extra space 304 (see FIG. 5). A breaker 23 is provided in the middle of the intake pipe 23a. An air tarina 154C is connected to the rear end of the intake pipe 23a.

[0067] The air cleaner 154C includes a box-shaped casing that is larger than the intake pipe 23a. Therefore, when installing the air cleaner 154C, a relatively large space is required. Therefore, in the present embodiment, as shown in FIG. 6, the air cleaner 154C is disposed above the engine unit 2 on the side opposite to the secondary sheave 56, that is, on the left side. This By providing the air cleaner 154C on the side opposite to the secondary sheave 56 as described above, contact between the air cleaner 154C and the transmission case 45 is prevented. Part of the Air Cleaner 154C overlaps with the secondary sheave 56 when viewed from the side. As a result, the air cleaner 154C partially overlaps the transmission case 45 in a side view, and a part of the air cleaner 154C is located inside the contour of the transmission case 45 in a side view. As a result, the overall height of the air cleaner 154C and the engine unit 2 is kept low.

Further, in the present engine unit 2, since the secondary sheave 56 is disposed above the primary sheave 55 ゃ drive shaft 48, there is a spatial margin around the drive shaft 48. Therefore, the layout around the drive shaft 48 can be determined relatively freely. Therefore, in the motorcycle 1 according to the present embodiment, the drive shaft 48 is provided at a position close to the pivot shaft 100 (see FIG. 1).

[0069] According to the motorcycle 1, for example, the length of the rear arm 8 can be increased, so that steering stability can be improved. In addition, the pivot shaft 100 can be positioned below the axis of the secondary sheave shaft 47. In addition, the force S can bring the drive shaft 48 and the pivot shaft 100 closer to each other. Therefore, when the lary arm 8 swings about the pivot shaft 100, the slack of the chain 50 wound around the drive shaft 48 can be reduced. Therefore, the transmission efficiency of the driving force to the rear wheel 7 can be improved, and the generation of noise due to the slack of the chain 50 can be suppressed.

In the above embodiment, the chain 50 for transmitting the driving force of the drive shaft 48 is the chain 50. However, the transmission member is not limited to the chain 50, and may be a transmission belt, a drive shaft, or the like. Even when a drive shaft or the like is used as the transmission member, a force S that can obtain substantially the same effect can be obtained because the distance between the drive shaft 48 and the pivot shaft 100 is short. That is, when the rear arm 8 swings about the pivot shaft 100, it is possible to suppress a decrease in the transmission efficiency of the driving force.

As described above, the pivot shaft 100 is preferably provided near the rear of the drive shaft 48. Note that the degree of “near” is not particularly limited, but, for example, within the radius of the secondary sheave 56, which is preferably within the diameter of the secondary sheave 56. Is particularly desirable.

In FIG. 4, reference numeral 150 indicates a kick starter axis. The kick starter shaft 150 is disposed below the drive shaft 48. The kick starter shaft 150 is disposed below the secondary sheave shaft 47. Further, kick starter shaft 150 is arranged inside the contour of crankcase 22 in side view. That is, the kick starter shaft 150 is arranged so as to fit within the profile of the crankcase 22.

As described above, the idler shaft 52 is disposed ahead of an imaginary line connecting the axis of the drive shaft 48 and the axis of the secondary sheave shaft 47. Therefore, by bringing the reduction gear (large reduction gear) 75 of the idle shaft 52 close to the primary sheave 55, the reduction gear 75 can be arranged so as to partially overlap the primary sheave 55 in a side view. As a result, the size of the rear part of the engine unit 2 can be further reduced. Reference numeral 156 is a balance weight.

Further, in the engine unit 2, the reduction gear (large reduction gear) 77 of the drive shaft 48 is disposed inside the contour of the transmission case 45 in a side view. Therefore, the engine unit 2 is further downsized.

FIG. 7 shows another embodiment of the engine according to the present invention. In this embodiment, the angle Θ formed between the axial direction of the cylinder block 19 and the longitudinal direction of the transmission case 45 (that is, the connection direction between the primary sheave shaft 55d and the secondary sheave shaft 47) is smaller than that in the previous embodiment. It is small. That is, the engine according to the present embodiment is a so-called upright engine, and the cylinder block 19 is formed in a more upright posture. The illustration of the air cleaner is omitted in FIG.

[0076] Also in the present embodiment, the intake system component 154 is disposed in the extra space 304 (see FIG. 5) above the engine unit 2. Therefore, when arranging the intake system components 154 (especially the calibrator 23), the secondary sheave 56 will not be in the way. Here, the carburettor 23 is arranged at a position overlapping with the transmission case 45 (specifically, a portion corresponding to the secondary sheave 56) in a side view. As described above, in the present embodiment, it is possible to arrange the secondary sheave 56 in the upper portion of the engine unit 2 in spite of being an upright engine. Therefore, the freedom of layout around the drive axis Can increase S power.

[0077] The engine of each of the above embodiments was provided with the calibrator 23 as a part of the intake system component 154. That is, in each of the above embodiments, a so-called breaker type fuel supply device is provided. However, the fuel supply device is not limited to the carburetor type, but may be a fuel injection type or the like. In an engine equipped with a fuel injection type fuel supply device, a throttle body, an injector, and the like are also part of the intake system components instead of the calibrator 23.

[0078] The position and degree of overlap between the intake system component 154 and the transmission case 45 are not limited to those in the above-described embodiments, and can be set as appropriate. Modifications and the like to each of the above embodiments are of course possible without departing from the spirit of the present invention.

Industrial applicability

As described above, the present invention is useful for an engine and a straddle-type vehicle for a straddle-type vehicle such as a motorcycle.

Claims

The scope of the claims

[1] an engine body having a crankshaft extending in the left-right direction and an intake port;

A transmission having a primary sheave that rotates according to the rotation of the crankshaft, a secondary sheave having a secondary sheave shaft extending in the left-right direction, and a transmission belt wound around the primary sheave and the secondary sheave.

An intake system component connected to an intake port of the engine body,

A straddle-type vehicle engine comprising:

An engine for a straddle-type vehicle, wherein at least a part of the intake system component overlaps the secondary sheave in a side view.

[2] The transmission is disposed on one of the left and right sides of the engine body,

The secondary sheave is disposed above the primary sheave, and the intake system component is disposed above the engine body and on the side opposite to the side where the transmission is provided in the left-right direction. The engine for a straddle-type vehicle according to claim 1, wherein:

3. The saddle-ride type vehicle engine according to claim 2, further comprising a kick starter shaft disposed below the secondary sheave.

[4] a transmission case accommodating the primary sheave, the secondary sheave, and the transmission belt;

A drive shaft directly or indirectly connected to the secondary sheave shaft, wherein the secondary sheave shaft is disposed above the drive shaft,

The intake system component is disposed above the engine body,

The saddle-ride type vehicle engine according to claim 1, wherein at least a part of the intake system component is disposed inside a contour of the transmission case in a side view.

5. The straddle-type vehicle engine according to claim 4, further comprising a kick starter shaft disposed below the secondary sheave.

[6] A saddle-ride type vehicle equipped with the saddle-ride type vehicle engine according to any one of claims 11 to 5.

[7] a vehicle main body that supports the saddle-ride type vehicle engine in a posture such that the drive shaft is located behind the crankshaft;

A rear arm that is swingably supported by the vehicle body and supports a rear wheel; and a transmission member that transmits a driving force from the drive shaft to the rear wheel. 7. The straddle-type vehicle according to claim 6, which is located behind the saddle-ride type vehicle engine in a side view.

8. The straddle-type vehicle according to claim 7, wherein a support point of the lear arm in the vehicle body is located below an axis of the secondary sheave shaft.

9. The straddle-type vehicle according to claim 7, wherein the support point of the lear arm in the vehicle body is located near the rear of the drive shaft.