JP6357126B2 - Saddle-type vehicle internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine mounted on a saddle riding type vehicle.

  Mounted in a saddle-ride type vehicle, the transmission is housed in a crankcase that supports the crankshaft, and power is applied to the rear wheels by a drive chain wound around a drive chain sprocket fitted to the output shaft of the transmission. There is a chain drive straddle-type vehicle internal combustion engine that is transmitted.

  In this internal combustion engine, the counter shaft serves as an output shaft out of the main shaft and the counter shaft that normally support the transmission gears that mesh with each other, and passes through the left side wall of the crankcase of the counter shaft. A drive chain sprocket is fitted to the end protruding from the left side, and the drive chain is disposed on the left side of the vehicle body.

  A friction clutch is provided at the end of the crankshaft of the main shaft penetrating the right side wall, and a release rod for releasing the connection of the friction clutch is slidably inserted through the shaft hole of the main shaft. An example in which the clutch release drive mechanism that acts on the left end of the rod is provided outside the same left side wall on which the drive chain sprocket of the crankcase is provided (see, for example, Patent Document 1) is generally known.

JP 2014-162269 A

  The internal combustion engine for a saddle-ride type vehicle disclosed in Patent Document 1 is provided with an AC generator at an end protruding through the left side wall of the crankcase of the crankshaft, and the AC generator is on the side of the AC generator. Covering from the side.

In the clutch release drive mechanism that acts on the left end of the release rod that passes through the shaft hole of the main shaft, the AC generator is located close to the front, and the drive chain sprocket fitted to the counter shaft is located behind. Therefore, there is no room for the space to arrange.
Therefore, in Patent Document 1, an ACG cover that covers the AC generator is extended rearward to hold the clutch release drive mechanism.

  The AC generator is a large-sized device, and the ACG cover that covers it is also large. However, in order to hold the clutch release drive mechanism, the ACG cover extends rearward and becomes larger and heavier. As a result, the internal combustion engine is increased in size and weight.

  The present invention has been made in view of the above points. The object of the present invention is that a clutch release drive mechanism is disposed compactly on one side wall of a crankcase provided with a drive chain sprocket, thereby reducing the size of an internal combustion engine. This is to provide a straddle-type vehicle internal combustion engine that can be reduced in weight.

In order to achieve the above object, a straddle-type vehicle internal combustion engine according to the present invention includes:
In an internal combustion engine mounted on a straddle-type vehicle with the crankshaft oriented in the left-right width direction of the vehicle body, the left and right side walls of a crankcase that rotatably supports the crankshaft by left and right bearings are mutually opposed to the transmission. A main shaft and a counter shaft, which are parallel to each other, which respectively support the meshing transmission gears, are rotatably supported by left and right bearings in the front and rear, respectively.
A drive chain sprocket is provided at an end of the counter shaft that protrudes outward from one side wall of the crankcase,
A clutch is provided at an end of the main shaft that protrudes outward from the other side wall of the crankcase;
A release rod that acts on the clutch to release the clutch is slidably inserted through the shaft hole of the main shaft and penetrates an oil seal press-fitted into the insertion hole of one side wall of the crankcase. Are provided with the end protruding outside,
A straddle-type vehicle internal combustion engine in which a clutch release driving mechanism is provided on the outer side of one side wall of the crankcase to act on an end of the release rod that protrudes through the oil seal and slides the release rod. In
A plate-shaped chain guide plate curved in a parabolic shape covering the front and upper and lower sides of the drive chain sprocket is attached to one side wall of the crankcase with the front portion being inserted through the release rod,
A sprocket cover that covers the drive chain sprocket from the side is attached to one side wall of the crankcase across the chain guide plate,
The sprocket cover is provided with the clutch release drive mechanism,
A cylindrical collar member inserted through the release rod is interposed between the oil seal and the chain guide plate ,
The clutch release drive mechanism (80)
A camshaft (82) extending in a direction perpendicular to the release rod from a cam portion (82c) that acts in contact with an end of the release rod (60);
A clutch actuating lever (83) extending in a direction perpendicular to the camshaft (82) by fitting a base end to the other end of the camshaft (82),
The end of the clutch cable (85) that moves forward and backward by clutch operation is coupled to the tip of the clutch operating lever (83),
The camshaft (82) extends obliquely upward and rearward from the cam portion (82c) contacting the end of the release rod (60),
The clutch actuating lever (83) fitted at the base end to the upper end of the camshaft (82) extends obliquely upward from the camshaft (82), and the tip can swing left and right.
A starter motor (35) is disposed above the upper wall obliquely above and behind the crankshaft (30) in the crankcase (21),
The clutch cable (85) coupled to the tip of the clutch operating lever (83) is connected between the starter motor (35) and the upper wall (21Uu) above the transmission (40) of the crankcase (21). It is characterized by passing almost horizontally through the space between

  According to this configuration, the clutch release drive mechanism is provided on the sprocket cover that is attached to one side wall of the crankcase with the chain guide plate inserted through the release rod at the front portion. The clutch release drive mechanism can be provided in a compact manner by avoiding an increase in the size of the device cover by providing a clutch release drive mechanism at a portion where the device cover covering the device such as an AC generator is extended greatly. A reduction in size and weight can be achieved.

In addition, since a cylindrical collar member inserted through the release rod is interposed between the oil seal and the chain guide plate, mud, sand, etc. scattered from the outside are formed in the gap formed in front of the sprocket cover. Even if it penetrates, the collar member can protect the release rod.
Furthermore, when the release rod slides, the collar member can prevent the oil seal from moving together and coming out of the insertion hole.
According to this configuration, the clutch operating lever having the base end portion fitted to the upper end of the camshaft extending obliquely upward and rearward from the cam portion that contacts the end portion of the release rod extends obliquely upward from the camshaft. The tip of the clutch actuating lever to which the end of the cable is coupled can be configured to protrude above the upper wall above the crankcase transmission, and the clutch cable can be separated from the space above the crankcase upper wall. It can arrange | position using.
According to this configuration, the clutch cable coupled to the tip of the clutch operating lever is between the starter motor disposed above the upper wall obliquely above and behind the crankshaft and the upper wall above the crankcase transmission. Therefore, the clutch cable can be arranged in a compact manner without interfering with the starter motor within the substantially left-right width of the internal combustion engine.
In addition, the clutch cable that passes through the space between the starter motor and the upper wall of the crankcase substantially horizontally can be arranged in a gentle curve toward the front of the vehicle, so that the clutch operation feels good. Does not worsen.

  In the above configuration, the collar member may be integrated with the chain guide plate.

  According to this configuration, the collar member is integrated with the chain guide plate, thereby preventing erroneous assembly and facilitating assembly.

  In the above configuration, one end of the collar member may be welded to the chain guide plate.

  According to this configuration, one end of the collar member is welded and integrated with the chain guide plate, thereby preventing erroneous assembly, reducing the number of parts, and facilitating assembly.

  The said structure WHEREIN: You may make it form the rod insertion hole which the said release rod of the front part of the said chain guide plate penetrates in the front-end convex part which protruded ahead.

  According to this configuration, since the rod insertion hole through which the release rod at the front part of the chain guide plate is inserted is formed in the front end convex part protruding forward, the front end convexity in which the rod insertion hole through which the release rod is inserted is formed. The front end where the drive guide chain comes into contact with the chain guide plate body and the rod insertion hole is inserted into the drive guide chain when the drive chain is broken. Since it does not directly contact the convex portion and the collar member, the release rod can be protected, and the front end convex portion does not interfere when the cut drive chain is discharged so that the chain guide plate body guides it.

In the above configuration,
The camshaft may be rotatably supported by the sprocket cover so as to overlap the drive chain sprocket in a side view.

  According to this configuration, the camshaft that extends in a direction perpendicular to the release rod from the cam portion that works in contact with the end portion of the release rod is rotatably supported by the sprocket cover so as to overlap the drive chain sprocket in a side view. Therefore, the camshaft is incorporated into the side wall of the sprocket cover in a small size, and a simple mechanical clutch release drive mechanism is provided in the sprocket cover in a compact manner, so that the internal combustion engine can be reduced in size and weight and cost can be reduced.

In the above configuration,
The clutch cable may pass above a speed sensor attached to an upper wall above the transmission of the crankcase.

  According to this configuration, since the clutch cable passes above the speed sensor attached to the upper wall above the transmission of the crankcase, the clutch cable is connected to the speed sensor and the starter motor on the upper wall of the crankcase. It can be arranged efficiently without interference.

In the present invention, since the clutch release drive mechanism is provided on the sprocket cover attached to one side wall of the crankcase with the chain guide plate penetrating the release rod at the front, the size of the equipment cover is avoided. The clutch release drive mechanism can be provided in a compact manner, and the internal combustion engine can be reduced in size and weight.
In addition, the release rod can be protected from mud, sand, etc. scattered from the outside, and the collar member prevents the oil seal from coming off.

1 is an overall side view of a motorcycle equipped with an internal combustion engine according to an embodiment of the present invention. It is the left view which expanded the internal combustion engine part of FIG. It is the perspective view which looked at the same internal combustion engine from the diagonally upper left. FIG. 4 is a cross-sectional view taken along arrow IV-IV in FIG. 2. It is a principal part expanded sectional view of FIG. It is a left view of the crankcase part of the internal combustion engine. FIG. 7 is a diagram in which a chain guide plate and a drive chain are disposed in the internal combustion engine of FIG. 6. It is the figure which attached the ACG cover and the sprocket cover to the internal combustion engine of FIG.

Hereinafter, an embodiment according to the present invention will be described with reference to FIGS.
FIG. 1 is a side view of a motorcycle 1 that is a straddle-type vehicle according to an embodiment to which the present invention is applied.
In the present specification and claims, the directions of front, rear, left and right are based on a normal standard in which the straight traveling direction of the motorcycle 1 according to the present embodiment is the front, and in the drawings, the arrow FR indicates the front, The arrow RR indicates the rear, the arrow LH indicates the left, and the arrow RH indicates the right.

  As shown in FIG. 1, the body frame 2 of the motorcycle 1 includes a pair of left and right upper main frames 4a and a lower main frame 4b extending from the head pipe 3 obliquely rearward and downward, and the upper main frame 4a. The rear end of the lower main frame 4b is coupled to the center frame 5.

A seat rail 6 extends rearward and obliquely upward from the rear portions of the upper main frame 4a and the lower main frame 4b, and an auxiliary frame 7 connects the seat rail 6 and the center frame 5.
From the front part of the lower main frame 4b, it branches downward and the down frame 8 extends obliquely rearward downward.

A front fork 9 extending downward is supported on the head pipe 3 so as to be steerable. A front wheel 10 is rotatably supported at the lower end of the front fork 9.
A steering handle 11 is integrally coupled to the upper end of the front fork 9.

The internal combustion engine 20 mounted on the motorcycle 1 is a water-cooled two-cylinder four-stroke internal combustion engine, and is supported by a support bracket 5 a protruding from the center frame 5 of the vehicle body frame 2 and a lower end 8 a of the down frame 8. Suspended.
The internal combustion engine 20 is mounted on the vehicle body frame 2 in a so-called horizontal position with the crankshaft 30 rotatably supported by the crankcase 21 oriented in the left-right width direction of the vehicle body.

  The crankcase 21 of the internal combustion engine 20 has a structure in which a transmission 40 is accommodated behind the crankshaft 30, and a counter of the main shaft 41 and the countershaft 42 that respectively supports the transmission gears that mesh with each other. The shaft 42 serves as an output shaft, and a drive chain sprocket 45 is fitted to an end of the counter shaft 42 that protrudes outside through the left side wall 21L of the crankcase 21 (see FIGS. 4 and 5).

On the other hand, a swing arm 13 whose front end is pivotally supported by a pivot shaft 12 on the center frame 5 of the body frame 2 extends rearward so that it can swing up and down. It is pivotally supported by the axle 14.
An endless drive chain 46 is suspended between the driven chain sprocket 16 fitted to the rear axle 14 and the drive chain sprocket 45 (see FIG. 1).

  The crankcase 21 is a combination of an upper crankcase half 21U and a lower crankcase half 21D that are vertically split. The crankcase 21 is formed on the split surfaces of the upper crankcase half 21U and the lower crankcase half 21D from the front. In order, the crankshaft 30, the main shaft 41, and the counter shaft 42 are arranged in parallel.

A cylinder block 22 in which two cylinder bores 22b, 22b are arranged in series in the left-right direction is stacked on the upper part of the upper crankcase half 21U in an inclined manner, and a cylinder head 23 is stacked on the cylinder block 22 And are fastened together.
A head cover 24 is put on the cylinder head 23.
An oil pan 25 is attached to the lower part of the lower crankcase half 21D.

As shown in FIG. 4, pistons 26 and 26 are fitted in the two cylinder bores 22b and 22b of the cylinder block 22 so as to be reciprocally slidable.
The piston 26 is connected to the crankshaft 30 via a connecting rod 27.
2 and 3, a starter motor 35 is disposed in the vicinity of the base portion behind the base portion of cylinder block 22 that tilts forward from upper crankcase half 21U and protrudes upward.

  Referring to FIG. 4, crankshaft 30 is rotatably supported by bearings 30b, 30b, and 30b on left and right side walls 21L and 21R facing each other and a central wall 21C therebetween, respectively. The main shaft 41 and the counter shaft 42 of the transmission 40 behind the crankshaft 30 are rotatably supported on the left and right side walls 21L and 21R of the crankcase 21 via left and right bearings 41b and 41b and left and right bearings 42b and 42b, respectively. Is done.

  The left side wall 21L of the crankcase 21 is formed by combining the left side wall of the upper crankcase half 21U and the left side wall of the lower crankcase half 21D with a split surface. Similarly, the crankcase 21 The right side wall 21R is also formed by combining the right side wall of the upper crankcase half 21U and the right side wall of the lower crankcase half 21D with a split surface.

The crankshaft 30 penetrates the left bearing 30b from the left side wall 21L of the crankcase 21 and protrudes the left shaft portion on the left outer side. The starting driven gear 31 and the AC generator 32 are sequentially provided on the protruding left shaft portion. It has been.
The AC generator 32 is covered with an ACG cover 33 from the left side.

  The starter driven gear 31 is rotatably supported on the crankshaft 30 via a bearing 30b, and is connected to an outer rotor 32r of an AC generator 32 fitted on the crankshaft 30 via a one-way clutch 34. Yes.

The drive of the starter motor 35 is transmitted to the starter driven gear 31 via an intermediate gear (not shown) interposed between the starter motor 35 and a drive gear 35g (see FIG. 6) formed on the drive shaft 35a of the starter motor 35. The
An inner stator 32 s disposed inside the outer rotor 32 r in the AC generator 32 is fixedly supported by the ACG cover 33.

The crankshaft 30 penetrates the right bearing 30b from the right side wall 21R of the crankcase 21 and protrudes the right shaft portion to the right outer side. The primary drive gear 36 and the cam chain drive sprocket 37 are projected to the protruding right shaft portion. Are sequentially inserted.
A timing chain 38 is bridged between the cam chain driven sprocket 37 and a cam chain driven sprocket fitted to a camshaft of a valve system (not shown).

  A transmission 40 that shifts the driving force of the internal combustion engine 20 to a predetermined gear stage is a constant-mesh transmission, and a drive gear group Gm from the first to sixth gears supported by the main shaft 41 and a counter. The driven gear group Gc from the first speed to the sixth speed supported by the shaft meshes with each speed correspondingly.

The main shaft 41 penetrates the right bearing 41b from the right side wall 21R of the crankcase 21 and protrudes the right shaft portion to the right outside. A multi-plate friction clutch 50 is provided on the protruding right shaft portion.
The clutch outer 51 of the friction clutch 50 forms a bottomed cylindrical body with a bottom portion 51b and a cylindrical portion 51c, and a circular hole formed in the center of the bottom portion 51b is rotatably fitted to the cylindrical base portion of the primary driven gear 39. The main shaft 41 is rotatably supported around the main shaft 41 and is connected to the primary driven gear 39 in the circumferential direction via a damper spring 39d.

A clutch inner 52 disposed inside the cylindrical portion 51c of the clutch outer 51 is spline-fitted to the main shaft 41 and rotates integrally with the main shaft 41.
The clutch inner 52 has a pressure receiving portion 52b facing the bottom portion 51b of the clutch outer 51 and a concentric cylindrical portion 52c facing the cylindrical portion 51c, and a cylinder 532c of the clutch inner 52 inside the cylindrical portion 51c of the clutch outer 51. A plurality of friction disks 53 and clutch disks 54 are alternately inserted into the outer annular space.

The friction disk 53 is fitted to the cylindrical portion 51 c of the clutch outer 51 so as to be slidable in the axial direction, and rotates integrally with the clutch outer 51.
Further, the clutch disk 54, which is alternately inserted into the friction disk 53, is fitted to the cylindrical portion 52c of the clutch inner 52 so as to be slidable in the axial direction, and rotates integrally with the clutch inner 52.

  The pressure plate 55 protrudes rightward from the main shaft 41 of the bottomed cylindrical cap member 61 fitted to the right end of the release rod 60 that is slidably inserted into the shaft hole formed in the main shaft 41. A shaft 62 is rotatably supported on the enlarged diameter bottom portion 61b via a bearing 62, and the pressure plate 55 presses the outermost friction disk 53 from the outside (right side) by the spring force of the clutch spring 56, and the pressure of the clutch inner 52 is received. The friction disk 53 and the clutch disk 54, which are alternately inserted between the portions 52b, are pressed together so as to be sandwiched from both sides, and the friction clutch 50 is in a connected state by friction between the friction disk 53 and the clutch disk 54.

  When the release rod 60 is pushed rightward, the pressure plate 55 moves rightward against the spring force of the clutch spring 56 via the bearing 62, so that the pressure of the friction disc 53 and the clutch disc 54 is released, A gap is formed between the two, and the friction clutch 50 is in a disconnected state.

  Referring to FIG. 5, the main shaft 41 has a left end supported by a left bearing 41 b on the left side wall 21 </ b> L of the crankcase 21, and the release rod 60 inserted through the shaft hole of the main shaft 41 has a main shaft 41. 41 protrudes to the left from the left end of 41 and penetrates the oil seal 63 press-fitted into the insertion hole 21h of the left side wall 21L of the crankcase 21 so that the left end protrudes outward.

  A clutch release drive mechanism 80 that acts on the left end portion of the release rod 60 and pushes the release rod 60 rightward to release the friction clutch 50 is provided outside the left side wall 21L of the crankcase 21.

As shown in FIG. 6, the left side surface of the left side wall 21 </ b> L of the crankcase 21 protrudes to the left around the outer rotor 32 r of the AC generator 32 fitted to the protruding left shaft portion of the crankshaft 30. An annular rib 21c that is an endless ridge is formed, and a curved rib 21p that is curved in a parabolic shape with the rear open is formed around the drive chain sprocket 45 that is fitted to the protruding left end of the counter shaft 42. The apex portion is cut out and divided into upper and lower parts.
The left end surfaces of the upper and lower curved ribs 21p, 21p form the same vertical plane.

An annular rib 21c around the outer rotor 32r of the AC generator 32 bulges obliquely upward rearward. The starter motor 35 is attached to the bulged portion of the annular rib 21c from the right side, and the drive shaft 35a is attached to the annular rib 21c. Project inward (see FIG. 6).
The left end surface of the annular rib 21 c is a mating surface with the ACG cover 33.

  Referring to FIG. 6, the crankshaft 30, the main shaft 41, and the countershaft 42 that are parallel to each other are lined up and down in this order on the split surfaces of the upper crankcase half 21U and the lower crankcase half 21D. The main shaft 41 and the release rod 60, which are arranged and located between the crankshaft 30 and the countershaft 42, are outside the annular rib 21c and at a rear position along the annular rib 21c.

The main shaft 41 is located at the apex of the parabola formed by the upper and lower curved ribs 21p, 21p formed above and below the drive chain sprocket 45, and the release rod 60 protrudes through the oil seal 63.
The release rod 60 protrudes into a notch where the upper and lower curved ribs 21p, 21p are separated.

The upper and lower curved ribs 21p, 21p are each formed with two mounting boss portions 21pb bulging outward.
Each mounting boss portion 21pb is formed with a screw hole.
A plate-like chain guide plate 65 curved in a parabolic shape covering the front and top and bottom of the drive chain sprocket 45 is brought into contact with the same vertical end surface of the upper and lower curved ribs 21p, 21p (see FIG. 7).

  As shown in FIG. 7, the chain guide plate 65 has the same shape as the parabolic curved shape formed by the upper and lower curved ribs 21p and 21p, and is cut out to separate the upper and lower curved ribs 21p and 21p. It abuts on the upper and lower curved ribs 21p and 21p so as to straddle the space (the apex portion of the parabolic curved shape).

  5 and 7, a front end convex portion 65a protruding forward is formed at the apex portion of the parabolic curved shape of the chain guide plate 65 straddling the upper and lower curved ribs 21p, 21p. A rod insertion hole 65h is formed in the convex portion 65a corresponding to the insertion hole 21h of the left side wall 21L of the crankcase 21, and a release rod 60 penetrating the oil seal 63 press-fitted into the insertion hole 21h of the crankcase 21 is provided. It protrudes through the rod insertion hole 65h of the chain guide plate 65.

As shown in FIG. 7, the upper and lower portions of the chain guide plate 65 have the same shape as the upper and lower curved ribs 21p, 21p, and the mounting convex portion 65b faces the mounting boss portion 21pb of the curved rib 21p. Is formed to protrude.
A mounting hole corresponding to the screw hole of the curved rib 21p is formed in the mounting convex portion 65b of the chain guide plate 65.

As shown in FIG. 5, the chain guide plate 65 through which the release rod 60 is inserted is a drive chain sprocket 45 whose left-right axial position is fitted to the left end of the counter shaft 42, that is, a drive chain wound around the drive chain sprocket 45. As shown in FIG. 7, the chain guide plate 65 extends in the vertical direction along the outer peripheral edge of the drive chain 46 from the front to the rear.
The chain guide plate 65 and the drive chain 46 are closest to each other at the front part, and the distance gradually increases as going back.

Accordingly, when the drive chain 46 is broken during rotation, the broken drive chain 46 comes into contact with the chain guide plate main body excluding the front end convex portion 65a and the mounting convex portion 65b of the chain guide plate 65.
Further, the parabolic, curved chain guide plate main body can guide the cut drive chain 46 and discharge it to the outside.

  As shown in FIG. 5, the release rod 60 protruding through the oil seal 63 press-fitted into the insertion hole 21h of the left side wall 21L of the crankcase 21 passes through the rod insertion hole 65h of the chain guide plate 65. The chain guide plate 65 located at the same left-right position as the drive chain 46 is separated from the oil seal 63 to the left, and the portion of the release rod 60 exposed between the chain guide plate 65 and the oil seal 63 is cylindrical. The color member 66 is covered.

The collar member 66 is integrated with the chain guide plate 65 by welding the left end portion thereof to the opening edge of the rod insertion hole 65h of the chain guide plate 65, and the right end portion of the collar member 66 is close to the oil seal 63. ing.
The collar member 66 may be integrated by pressing the left end portion into the rod insertion hole 65h of the chain guide plate 65.

As shown in FIGS. 5 and 8, the drive chain sprocket 45 around which the drive chain 46 is wound is covered with a sprocket cover 70 from the side.
The sprocket cover 70 is parabolically curved like the chain guide plate 65 and covers the front and upper sides of the drive chain sprocket 45. The sprocket cover 70 extends inward from the left end of the cover peripheral wall 71 and is triangular in side view. The cover side wall 72 is formed in a shape and faces the drive chain sprocket 45 and covers the left side.

On the cover peripheral wall 71 of the sprocket cover 70, an attachment boss 71b bulges outward corresponding to the attachment protrusion 65b of the chain guide plate 65.
The mounting boss 71b of the sprocket cover 70 is formed with a mounting hole coaxial with the mounting hole of the mounting projection 65b of the chain guide plate 65 and the screw hole of the curved rib 21p of the crankcase 21.

As shown in FIG. 5, a peripheral wall cylindrical portion 71s oriented in the left-right direction closes the left side of the cover peripheral wall 71 of the sprocket cover 70 corresponding to the rod insertion hole 65h of the chain guide plate 65. It is opened and formed coaxially with the rod insertion hole 65h.
Further, as shown in FIG. 8, a side wall cylindrical portion 72s is formed on the cover side wall 72 of the sprocket cover 70 so as to be inclined obliquely upward and rearward from the left end portion of the peripheral wall cylindrical portion 71s.
The peripheral wall cylindrical portion 71 s and the side wall cylindrical portion 72 s are three-dimensionally crossed in a direction perpendicular to each other with some mutual center axes.

A clutch release drive mechanism 80 for sliding the release rod 60 is incorporated in a sprocket cover 70 that covers the drive chain sprocket 45 from the side.
As shown in FIG. 5, a sliding pressing member 81 is slidably inserted in the peripheral wall cylindrical portion 71s formed on the cover peripheral wall 71 of the sprocket cover 70 so as to be slidable in the left-right direction. The left end portion of the release rod 60 is fitted into the right cylindrical portion of 81.

5 and 8, a cylindrical cam shaft 82 is inserted into a side wall cylindrical portion 72s formed on the cover side wall 72 of the sprocket cover 70.
The camshaft 82 has a cam portion 82c formed by notching an annular cross section at an angle of 90 degrees from the center at the tip portion, and the left end surface of the sliding pressing member 81 is formed in the notched cam portion 82c. Are in contact.

  The cam portion 82c at the tip of the camshaft 82 is in contact with the left end surface of the sliding pressing member 81 at the location where the peripheral wall cylindrical portion 71s and the side wall cylindrical portion 72s intersect, and the camshaft 82 rotates to thereby The sliding pressing member 81 that contacts the cam portion 82c of the shaft 82 can be slid to the right together with the release rod 60.

Referring to FIG. 3, the camshaft 82 inserted into the side wall cylindrical portion 72s has an end portion on the opposite side to the cam portion 82c protruding outward from the side wall cylindrical portion 72s, and a clutch is operated on the protruding end portion. The base end portion of the lever 83 is fitted.
The clutch operating lever 83 extends in a direction perpendicular to the camshaft 82 from a base end portion that is fitted to the camshaft 82.

  A portion of the camshaft 82 exposed to the outside from the side wall cylindrical portion 72s is wound with a torsion coil spring 84, one end of which is fixed to the side wall cylindrical portion 72s, and the other end is locked to the clutch operating lever 83. Along with the operating lever 83, the camshaft 82 is urged to rotate in one direction.

  Thus, the clutch release drive mechanism 80 including the sliding pressing member 81, the camshaft 82, the clutch operating lever 83, and the like is provided on the sprocket cover 70 that covers the drive chain sprocket 45 from the side.

  The sprocket cover 70 in which the clutch release drive mechanism 80 is incorporated so that the cover peripheral wall 71 sandwiches the chain guide plate 65 abutting against the upper and lower curved ribs 21p, 21p of the left side wall 21L of the crankcase 21 from the left side. The fastening bolt 75 is inserted into the mounting hole where the mounting boss portion 71b of the sprocket cover 70 and the mounting convex portion 65b of the chain guide plate 65 coincide with each other, and screwed into the screw hole of the mounting boss portion 21pb of the crankcase 21 The sprocket cover 70 is fastened together with the chain guide plate 65 to the left side wall 21L of the crankcase 21 and attached.

  When the cover peripheral wall 71 of the sprocket cover 70 is in contact with the chain guide plate 65, the left end portion of the release rod protruding from the rod insertion hole 65h of the chain guide plate 65 is the right side of the sliding pressing member 81 in the peripheral wall cylindrical portion 71s. It fits in the cylindrical part.

When the sprocket cover 70 is thus attached to the left side wall 21L of the crankcase 21 across the chain guide plate 65, the peripheral wall cylindrical portion 71s of the sprocket cover 70 contacts the chain guide plate 65, as shown in FIG.
Since the collar member 66 welded to the chain guide plate 65 is close to the oil seal 63, the release rod 60 is almost completely covered. The collar member 66 can protect the release rod 60 even if mud, sand, or the like scattered from the outside enters the gap formed in FIG.

When the sprocket cover 70 is attached to the left side wall 21L of the crankcase 21, as shown in FIG. 8, the side wall cylindrical portion 72s formed on the cover side wall 72 of the sprocket cover 70 is inclined upward from the left end portion of the peripheral wall cylindrical portion 71s. The camshaft 82 inserted into the side wall cylindrical portion 72s extends obliquely upward and rearward from the left end portion of the sliding pressing member 81 inserted into the peripheral wall cylindrical portion 71s. A clutch operating lever 83 having a base end portion fitted to an upper end protruding from the side wall cylindrical portion 72s of the cam shaft 82 extends obliquely upward and forward in a direction perpendicular to the cam shaft 82.

Therefore, as shown in FIGS. 2 and 3, the tip (upper end) of the clutch operating lever 83 is positioned above the upper wall 21Uu above the transmission 40 of the crankcase 21 and can swing left and right. Yes.
An end of the clutch cable 85 is coupled to the tip (upper end) of the clutch operating lever 83.
The clutch cable 85 extends in the right direction from the coupling end with the tip of the clutch operating lever 83, and then is arranged in a gentle curve toward the front of the vehicle body, and is connected to a clutch operating lever (not shown) of the steering handle 11. ing.

  When the clutch operating lever is operated and the clutch cable 85 is pulled, the clutch operating lever 83 swings to the right, rotates the camshaft 82, pushes the release rod 60 to the right via the cam portion 82c, Release the friction clutch 50.

  As shown in FIG. 3, the portion of the clutch cable 85 that extends substantially horizontally from the coupling end with the tip of the clutch operating lever 83 is the upper wall 21Uu above the transmission 40 of the crankcase 21 and the upper crank. A space sandwiched between the starter motor 35 provided in the vicinity of the base portion of the cylinder block 22 that protrudes upward from the case half 21U and extends upward and horizontally extends along the upper wall 21Uu of the crankcase 21. It is arranged.

  A speed sensor 90 that detects the rotational speed of one of the drive gear groups Gm supported on the main shaft 41 of the transmission 40 is provided on the upper wall 21Uu of the crankcase 21 above the transmission 40. The clutch cable 85 extends close to the top of the speed sensor 90 in the horizontal direction (see FIG. 3).

As shown in FIG. 3, a cable holder 86 for holding a clutch cable 85 extending rightward from the tip of the clutch operating lever 83 is provided so as to be fixed to the protruding portion 21Ub of the upper crankcase half 21U. .
The clutch cable 85 is covered with a cable outer (not shown), and the cable holder 86 holds the clutch cable 85 by grasping the cable outer.

As described above, the embodiment of the straddle-type vehicle internal combustion engine according to the present invention described in detail has the effects described below.
As shown in FIG. 5, the clutch release drive mechanism 80 is provided on the sprocket cover 70 attached to the left side wall 21L of the crankcase 21 with the chain guide plate 65 inserted through the release rod 60 at the front. By avoiding the increase in size of the ACG cover 33 due to the provision of the clutch release drive mechanism 80 at the portion where the ACG cover 33 extends greatly rearward, the clutch release drive mechanism 80 can be provided in a compact manner. And weight reduction can be achieved.

Further, as shown in FIG. 5, since the collar member 66 inserted through the release rod 60 is interposed between the oil seal 63 and the chain guide plate 65, a gap formed in front of the sprocket cover 70. Even if mud, sand, etc., scattered from the outside enter, the collar member 66 can protect the release rod 60.
Further, when the release rod 60 slides, the collar member 66 can prevent the oil seal 63 from moving together and coming out of the insertion hole 21h of the left side wall 21L.

  By integrating the collar member 66 with the chain guide plate 65, it is possible to prevent erroneous assembly and facilitate assembly.

By welding and integrating one end of the collar member 66 to the chain guide plate 65, erroneous assembly can be prevented, the number of parts can be reduced, and assembly can be facilitated.

As shown in FIG. 7, the rod insertion hole 65h through which the release rod 60 at the front part of the chain guide plate 65 is inserted is formed in the front end convex part 65a protruding forward, so that the rod insertion hole through which the release rod is inserted. When there is a chain guide plate body on the side of the drive chain 46 behind the front end convex portion 65a where the 65h is formed and the drive chain 46 breaks, the drive chain 46 comes into contact with the chain guide plate body, and the release rod Since the front end convex portion 65a in which the rod insertion hole 65h is inserted and the collar member 66 are not directly in contact with each other, the release rod 60 can be protected and the cut drive chain 46 can be attached to the chain guide plate body. The front end convex portion 65a does not hinder when discharging so as to guide.

As shown in FIG. 8, the camshaft 82 extending in a direction perpendicular to the release rod 60 from the cam portion 82c acting in contact with the end of the release rod 60 overlaps the drive chain sprocket 45 in a side view. Since it is rotatably supported by the cover 70, the camshaft 82 is incorporated into the cover side wall 72 of the sprocket cover 70 in a small size, and a simple mechanical clutch release drive mechanism 80 is provided in the sprocket cover 70 in a compact manner. Can be reduced in size and weight and cost can be reduced.

As shown in FIGS. 3 and 8, a clutch operating lever 83 having a base end portion fitted to an upper end of a camshaft 82 extending obliquely upward and rearward from a cam portion 82c contacting the end portion of the release rod 60 is provided on the camshaft. Since it extends obliquely above 82, the tip of the clutch operating lever 83 to which the end of the clutch cable 85 is coupled may be configured to protrude above the upper wall 21Uu above the transmission 40 of the crankcase 21. The clutch cable 85 can be arranged using the space above the upper wall 21Uu of the crankcase 21.

As shown in FIG. 3, the clutch cable 85 coupled to the tip of the clutch operating lever 83 is a transmission between the starter motor 35 and the crankcase 21 disposed above the upper wall 21Uu obliquely above and behind the crankshaft 30. Since the space between the upper wall 21Uu above 40 and the upper wall 21Uu passes substantially horizontally, the clutch cable 85 can be disposed compactly within the substantially left-right width of the internal combustion engine 20 without interfering with the starter motor 35.
In addition, the clutch cable 85 that passes substantially horizontally through the space between the starter motor 35 and the upper wall 21Uu of the crankcase 21 can be arranged in a gentle curve toward the front of the vehicle, so that the clutch operation Does not worsen the feeling.

As shown in FIG. 3, since the clutch cable 85 passes above the speed sensor 90 attached to the upper wall 21Uu above the transmission 40 of the crankcase 21, the clutch cable 85 is connected to the upper wall 21Uu of the crankcase 21. Can be efficiently disposed without interfering with the speed sensor 90 and the starter motor 35.

  The straddle-type vehicle internal combustion engine according to the embodiment of the present invention has been described above. However, the aspect of the present invention is not limited to the above-described embodiment, and various aspects are within the scope of the gist of the present invention. Including what is implemented in.

For example, the vehicle of the present invention is not limited to the straddle-type motorcycle 1 of the embodiment, but may be a variety of straddle-type vehicles such as a scooter type, a three-wheel, and a four-wheel buggy. Any vehicle having the requirements may be used.
Moreover, it is also possible to arrange all the devices arranged on the left and right sides of the internal combustion engine in the straddle-type vehicle internal combustion engine according to the embodiment all at once on the left and right sides.

DESCRIPTION OF SYMBOLS 1 ... Motorcycle, 20 ... Internal combustion engine, 21 ... Crankcase, 21L ... Left side wall, 21p ... Curved rib, 30 ... Crankshaft, 32 ... AC generator, 33 ... ACG cover, 35 ... Starter motor,
40 ... transmission, 41 ... main shaft, 42 ... counter shaft, 45 ... drive chain sprocket, 46 ... drive chain, 50 ... friction clutch,
60 ... Release rod, 63 ... Oil seal, 65 ... Chain guide plate, 65h ... Rod insertion hole, 66 ... Collar member,
70… Sprocket cover, 71… Cover peripheral wall, 72… Cover side wall,
80 ... Clutch release drive mechanism, 81 ... sliding pressing member, 82 ... cam shaft, 83 ... clutch operating lever, 85 ... clutch cable, 90 ... speed sensor.

Claims (6)

The crankcase (21) of the internal combustion engine mounted on the saddle riding type vehicle with the crankshaft (30) oriented in the lateral width direction of the vehicle body is opposed to each other with the crankcase (21) rotatably supported by the left and right bearings. The main shaft (41) and the counter shaft (42) that are parallel to each other and support the transmission gear that meshes with each other on the left and right side walls (21L, 21R) are rotatably supported by the left and right bearings, respectively. Pivoted,
A drive chain sprocket (45) is provided at the end of the countershaft (42) protruding outward from one side wall (21L) of the crankcase (21),
A clutch (50) is provided at an end of the main shaft (41) protruding outward from the other side wall (21R) of the crankcase (21),
A release rod (60) acting on the clutch (50) to release the connection of the clutch (50) is slidably inserted through the shaft hole of the main shaft (41), and the crankcase (21) Provided through the oil seal (63) press-fitted into the insertion hole of the one side wall (21L), with the end protruding outside.
A clutch release drive mechanism (80) that acts on an end of the release rod (60) that protrudes through the oil seal (63) and slides the release rod (60) is provided on the crankcase (21). In the internal combustion engine for straddle-type vehicles provided outside the one side wall (21L),
A parabolic curved plate-shaped chain guide plate (65) covering the front and upper and lower sides of the drive chain sprocket (45) is inserted into the release rod (60) at the front portion and one side of the crankcase (21). Attached to the side wall (21L)
A sprocket cover (70) covering the drive chain sprocket (45) from the side is attached to one side wall (21L) of the crankcase (21) across the chain guide plate (65),
The sprocket cover (70) is provided with the clutch release drive mechanism (80),
A cylindrical collar member (66) inserted through the release rod (60) is interposed between the oil seal (63) and the chain guide plate (65) ,
The clutch release drive mechanism (80)
A camshaft (82) extending in a direction perpendicular to the release rod from a cam portion (82c) that acts in contact with an end of the release rod (60);
A clutch actuating lever (83) extending in a direction perpendicular to the camshaft (82) by fitting a base end to the other end of the camshaft (82),
The end of the clutch cable (85) that moves forward and backward by clutch operation is coupled to the tip of the clutch operating lever (83),
The camshaft (82) extends obliquely upward and rearward from the cam portion (82c) contacting the end of the release rod (60),
The clutch actuating lever (83) fitted at the base end to the upper end of the camshaft (82) extends obliquely upward from the camshaft (82), and the tip can swing left and right.
A starter motor (35) is disposed above the upper wall obliquely above and behind the crankshaft (30) in the crankcase (21),
The clutch cable (85) coupled to the tip of the clutch operating lever (83) is connected between the starter motor (35) and the upper wall (21Uu) above the transmission (40) of the crankcase (21). A straddle-type vehicle internal combustion engine characterized by passing through a space between them substantially horizontally .   The straddle-type vehicle internal combustion engine according to claim 1, wherein the collar member (66) is integrated with the chain guide plate (65).   The straddle-type vehicle internal combustion engine according to claim 2, wherein one end of the collar member (66) is welded to the chain guide plate (65).   The rod insertion hole (65h) through which the release rod (60) at the front part of the chain guide plate (65) is inserted is formed in a front end convex part (65a) protruding forward. A straddle-type vehicle internal combustion engine according to any one of claims 3 to 4.   5. The sprocket cover (70) is rotatably supported by the sprocket cover (70) so that the camshaft (82) overlaps the drive chain sprocket (45) in a side view. A straddle-type vehicle internal combustion engine according to claim 1. The clutch cable (85) comprises claims 1, characterized in that through the above the speed sensor attached to a wall (21Uu) over the upper transmission crankcase (21) (40) (90) The internal combustion engine for straddle-type vehicles according to claim 5 .

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