CN107882628B

CN107882628B - Cam chain guide device for internal combustion engine

Info

Publication number: CN107882628B
Application number: CN201710887986.2A
Authority: CN
Inventors: 内田博之; 原田诚
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 2016-09-30
Filing date: 2017-09-27
Publication date: 2021-01-12
Anticipated expiration: 2037-09-27
Also published as: JP6438925B2; BR102017020198A2; JP2018053883A; CN107882628A

Abstract

A cam chain guide device for an internal combustion engine (1) includes a drive sprocket (59), a driven sprocket (53), a cam chain (54) that passes around the sprockets, a guide roller (55), a cam chain tensioner (8), and a sub-guide roller (56). The driven sprocket (53) receives a rotational force from the crankshaft (21) through the cam chain (54) and rotates the camshaft (51). The guide roller (55) guides the cam chain on an inner peripheral side of the cam chain. The cam chain tensioner (8) presses the cam chain from the outer peripheral side by a tension roller (82) to apply tension to the cam chain. The sub guide roller (56) cooperates with the tension roller (82) to press the cam chain therebetween in directions opposite to each other. The diameter of the guide roller (55) is equal to the diameter of the driven sprocket (53). The above arrangement prevents the cam chain from swinging between the driven sprocket and the guide roller.

Description

Cam chain guide device for internal combustion engine

Technical Field

The invention relates to a cam chain guide device for an internal combustion engine, which can prevent a cam chain from swinging.

Background

For example, the following patent document 1 discloses a cam chain guide device for an internal combustion engine. The cam chain guide includes a cam chain tensioner and a secondary guide roller. The cam chain tensioner has a tension roller that presses a cam chain that passes around a drive sprocket on a crankshaft and a driven sprocket on a camshaft. The tension roller applies a tension to the outer peripheral side of an extension of the cam chain from the drive sprocket to the driven sprocket. The cam chain guide device further includes a sub-guide roller for guiding the cam chain so as to cooperate with the tension roller to press the cam chain therebetween in directions opposite to each other. In the cam chain guide device, a guide roller is further provided between the tension roller and the driven sprocket to guide the cam chain at an inner periphery of the cam chain.

In the cam chain guide device disclosed in patent document 1, the swing or vibration of the cam chain between the guide roller and the sub guide roller can be effectively suppressed by the tension of the cam chain applied by the cam chain tensioner. However, since there is a difference in the width in the diameter direction of the driven sprocket and the guide roller, there is a risk that the cam chain swings or vibrates between the driven sprocket and the guide roller.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 5009834 (FIGS. 2 to 4)

Disclosure of Invention

Technical problem

The present invention has been made in view of the above-mentioned prior art, and an object of the present invention is to provide a cam chain guide device for an internal combustion engine, which is capable of preventing the swing or vibration of a cam chain between a driven sprocket and a guide roller, the cam chain guide device including a guide roller disposed on an inner peripheral side of the cam chain between the driven sprocket and a drive sprocket and a tension roller disposed to cooperate with a sub-guide roller to press the cam chain therebetween in directions opposite to each other.

Solution to the problem

In order to solve the problem, the present invention provides a cam chain guide device for an internal combustion engine, including: a crankshaft of the engine; a camshaft of the valve train; a driven sprocket receiving a rotational force from the crankshaft through an endless cam chain and the driven sprocket on the camshaft to rotate the crankshaft; a guide roller provided inside a path of the endless cam chain to guide the cam chain; a cam chain tensioner provided on the crankshaft side with respect to the guide roller and having a tension roller to press the cam chain from outside a path of the cam chain to apply a tension to the cam chain; and a sub guide roller provided on an opposite side of the tension roller with respect to the cam chain and cooperating with the tension roller to guide the cam chain so as to press the cam chain in a direction opposite to a direction in which the tension roller presses the cam chain; wherein a diameter of the guide roller is equal to a diameter of the driven sprocket.

With this configuration, by making the driven sprocket and the guide roller have equal diameters, the movement or vibration of the cam chain becomes small, and the swing of the cam chain can be prevented. The above-described movement of the cam chain is in a direction orthogonal to the advancing direction of the cam chain between the driven sprocket and the guide roller in an imaginary plane including the driven sprocket plane and orthogonal to the camshaft.

In a preferred embodiment of the present invention, the inter-axis distance between the axis of the cam shaft and the axis of the shaft of the guide roller and the inter-axis distance between the axis of the shaft of the guide roller and the shaft of the sub-guide roller are equal to each other.

With this configuration, since the inter-axis distance from the axis of the cam shaft to the axis of the guide roller shaft and the inter-axis distance from the axis of the guide roller shaft to the axis of the sub-guide roller shaft of the sub-guide roller are equal to each other, so that the elongation of the cam chain between the driven sprocket and the guide roller and the elongation of the cam chain between the guide roller and the sub-guide roller are equal to each other, it is possible to suppress the bias of the deflection of the cam chain.

In a preferred embodiment of the present invention, the cam chain tensioner comprises an oil-locked tensioner lifter provided in a bearing wall of the crankcase, and a push rod slidably inserted into the tensioner lifter; the tension roller is supported by a tension lever pivotally supported in the crankcase so as to be pressed against the cam chain by the push rod; the oil reservoir is provided in a bearing wall facing the cam chain chamber; the oil guide rib is arranged in the crank case, protrudes from the bearing wall facing the cam chain cavity, and the lower end part of the oil guide rib extends to the area above the oil storage part when viewed from the axial direction of the crank shaft; the oil locking tensioner lifter is communicatively connected to the oil reservoir.

With the above configuration, the oil-pressure-locking tensioner lifter is connected to the oil reservoir, the oil reservoir is disposed in the bearing wall, the bearing wall faces the cam chain chamber, the push rod is inserted into the oil-pressure-locking tensioner lifter, the oil guide rib is provided to supply oil to the oil reservoir, the oil guide rib is disposed to protrude from the bearing wall, and the bearing wall faces the cam chain chamber. Therefore, oil shortage of the oil-pressure-locking tensioner lifter is prevented, the tension roller reliably operates, and the effect of suppressing the cam chain swing by the guide roller is ensured.

The invention has the advantages of

The cam chain guide device for an internal combustion engine according to the present invention reduces the movement of the cam chain by making the driven sprocket and the guide roller have the same diameter, and can prevent the swing of the cam chain in the direction orthogonal to the advancing direction of the cam chain between the driven sprocket and the guide roller in the imaginary plane including the driven sprocket plane and orthogonal to the camshaft.

Drawings

Fig. 1 is a left side view of an internal combustion engine including a cam chain guide device for an internal combustion engine related to an embodiment of the invention, in which a part of the engine is sectioned and a part of the rear is omitted in the drawing;

FIG. 2 is a cross-sectional view of the internal combustion engine viewed generally along the arrowed line II-II in FIG. 1; and

fig. 3 is a sectional view showing the configuration of the cam chain tensioner as viewed along the line III-III in fig. 1.

Detailed Description

A cam chain guide device of an internal combustion engine according to an embodiment of the present invention will be described with reference to fig. 1 to 3.

In the description of the present specification, directions such as front, rear, left, right, up and down are consistent with those of a vehicle (for example, a motorcycle) in a state where an internal combustion engine related to an embodiment is mounted on the vehicle, which is not shown.

In the posture shown in fig. 1, the left side in the drawing is the vehicle front, the upper side in the drawing is the vehicle upper side, the right side in the drawing is the vehicle rear, and the near side in the drawing is the vehicle left side.

In the figure, an arrow FR shows the vehicle front, an arrow LH shows the vehicle left, an arrow RH shows the vehicle right, and an arrow UP shows the vehicle upper.

Fig. 1 is a left side view of an internal combustion engine 1 including a cam chain guide device for an internal combustion engine related to an embodiment of the invention, in which a part of the internal combustion engine 1 is sectioned and a part of the rear is omitted from the drawing. The internal combustion engine 1 is an air-cooled single cylinder-4 stroke cycle SOHC internal combustion engine.

The internal combustion engine 1 is mounted on a motorcycle, not shown, with its crankshaft 21 oriented in the vehicle width direction, i.e., the left-right direction of the vehicle as a motorcycle on which the engine 1 is mounted.

The internal combustion engine 1 constitutes a so-called power unit in which a transmission 3 is disposed in a rear portion of a crankcase 2. The crankcase 2 rotatably supports a crankshaft 21 therein.

As shown in fig. 1, the cylinder block 4 and the cylinder head 5 are continuously overlapped and integrally fastened to each other obliquely above the crank case 2. The cylinder head cover 6 covers the cylinder head 5 from the top, and the cylinder block 4, the cylinder head 5, and the cylinder head cover 6 are arranged to project upward from the crank case 2 to be slightly inclined forward.

Fig. 2 is a sectional view of the internal combustion engine, as viewed generally along the arrowed line II-II in fig. 1.

As shown in fig. 2, the crank case 2 is divided into a left crank case portion 2L and a right crank case portion 2R, and the crankshaft 21 is rotatably supported by a left bearing wall 22L of the left crank case portion 2L and a right bearing wall 22R of the crank case portion 2R via main bearings 23.

For the crankshaft 21, left and right crank webs 21w are provided in the crank chamber 20. The crank chamber 20 is disposed between the left bearing wall 22L and the right bearing wall 22R, the left and right crank webs 21w are engaged with each other by the crank pin 21p, the left crank part 21L and the right crank part 21R are projected to the left and right outer sides of the left bearing wall 22L and the right bearing wall 22R, and the left housing cover 7L and the right housing cover 7R cover the outer sides of the left crank part 21L and the right crank part 21R.

A main shaft 31 and a counter shaft 32 of the transmission 3 are rotatably supported by the crank case 2 so as to be parallel to the crankshaft 21, and a speed change gear set 30g of a normal engagement type is arranged on the main shaft 31 and the counter shaft 32.

A speed change clutch device 35 including a main driven gear 34 is attached to the right end of the main shaft 31, the main driven gear 34 meshing with the main drive gear 33. A main drive gear 33 is fittingly attached to the right end of the right crankshaft portion 21R, and the rotation of the crankshaft 21 is transmitted to a main driven gear 34.

The transmission clutch device 35 is connected/disconnected according to a shift operation, and changes a combination of gears transmitting rotation in the speed change gear group 30g between the main shaft 31 and the counter shaft 32 by a not-shown shift mechanism to perform shifting.

After the gear change, the rotation of the counter shaft 32 is transmitted from the output sprocket 36 to the rear wheel, which is a driving wheel of the motorcycle not shown, through the driving chain 37, and the output sprocket 36 is fittingly attached to the left end of the counter shaft 32.

A drive sprocket 59 of the valve drive system or valve train 50 is fittingly attached to the left crankshaft section 21L near the main bearing 23.

On the other hand, the valve train 50 is disposed in the cylinder head 5, the camshaft 51 is pivotably supported by the upper surface of the cylinder head 5 so as to be sandwiched by the camshaft holder 52 so as to be parallel to the crankshaft 21, i.e., oriented in the width direction of the vehicle, and the driven sprocket 53 is fittingly attached to the left end of the camshaft 51, the diameter of the driven sprocket 53 being 2 times the diameter of the drive sprocket 59 of the valve drive system.

The cam chain 54 is stretched between the driven sprocket 53 and the driving sprocket 59, and the cam chain 54 is a continuous endless transmission chain. The driven sprocket 53 is fittingly attached to the camshaft 51, the driving sprocket 59 is fittingly attached to the crankshaft 21, and the rotation of the crankshaft 21 is transmitted to the camshaft 51 with the rotation speed reduced to half.

Cam chain chambers

2c, 4c, and 5c are formed in respective left portions of the crank case 2, the cylinder block 4, and the cylinder head 5. The

cam chain chambers

2c, 4c, and 5c communicate with each other, and the cam chain 54 is provided to extend through the

cam chain chambers

2c, 4c, and 5c.

The cam chain chamber 2c of the crank case 2 is formed between the left bearing wall 22L of the left crank case 2L and the separator member 26. The separator member 26 is attached so as to block the circular opening portion 25, and has a circular outer periphery. A circular opening portion 25 opens in the outer wall 2a on the left outer side of the left bearing wall 22L.

The separator member 26 is arranged to separate the inside and outside of the cam chain chamber 2c from each other in the vehicle width direction of the cam chain chamber 2c.

In addition, a state in which the separator member 26 is separated and the opening portion 25 of a circular shape is seen is shown in fig. 1.

In addition, in the present embodiment, the opening center 25a of the circular opening portion 25 is arranged at a position eccentric to the axis 21a of the crankshaft 21, as shown in fig. 1.

Therefore, the distance from the axis 21a of the crankshaft 21 to the inner periphery 25b of the circular opening portion 25 is varied, and therefore it is not necessary to position the member to be mounted on the inner side of the circular opening portion 25 in the vehicle width direction, that is, the sub guide roller 56 described below, for example, in a constant range around the crankshaft 21, and the degree of freedom of layout within the crankcase 2 is improved.

The left crankshaft portion 21L penetrates the separator member 26 in an oil-tight manner, the alternator 10 is disposed on the left side of the separator member 26, and the alternator 10 is covered by the left housing cover 7L.

The separator member 26 is fastened to a boss 28 of the left bearing wall 22L by an attachment bolt 27, and the inner stator 10a of the alternator 10 is attached to the outer surface of the separator member 26, and the outer rotor 10b of the alternator 10 is attached to the left end portion of the left crankshaft portion 21L, the outer rotor 10b surrounding the inner stator 10 a.

As shown in fig. 1, in the cam chain chamber 4c of the cylinder 4, a guide roller 55 having the same diameter as the driven sprocket 53 is rotatably supported (refer to fig. 2). The guide roller 55 is disposed in a rotation path of the cam chain 54, and operates to guide the rotating cam chain 54 to push the cam chain 54 from an inner peripheral side of the cam chain 54 to an outer peripheral side thereof. When the cam chain 54 rotates, the guide rollers 55 guide the cam chain 54 in the deflecting movement on the front and rear sides of the cam chain 54.

In the present embodiment, the guide roller 55 is rotatably supported by the guide roller shaft 57. The guide roller shaft 57 is screwed from the outer wall 4a of the cylinder block 4 (refer to fig. 2) toward the inside of the cam chain chamber 4c.

In the present specification and claims, "equal diameter" means that the radial direction distance r53 of the driven sprocket 53 and the radial direction distance r55 of the guide roller 55 are equal to each other. The radial direction distance r53 is the distance from the rotation center 53c of the driven sprocket 53 to the pin center 54p of the cam chain 54, and the cam chain 54 wraps around and contacts the driven sprocket 53. The radial direction distance r55 is a distance from the rotation center of the guide roller 55 to the pin center 54p of the cam chain 54, and the cam chain 54 is pressed toward and in contact with the guide roller 55. "equal diameter" means a distance within manufacturing tolerances.

In the illustration of fig. 1, crankshaft 21 rotates in counterclockwise direction R. Therefore, the front side of the cam chain 54 extending between the driven sprocket 53 and the drive sprocket 59 is the side pulled downward by the drive sprocket 59, i.e., the "tight side", and the rear side of the cam chain 54 is the side transmitted upward by the drive sprocket 59, i.e., the "loose side".

As shown in fig. 1, in the cam chain chamber 2c of the crank case 2, the sub guide roller 56 is configured to be rotatably supported by the left bearing wall 22L at a position obliquely upward with respect to the front portion of the drive sprocket 59, and is provided to press the front extension portion of the cam chain 54 inward or rearward from the outer peripheral side of the cam chain 54 to guide the deflecting motion of the cam chain 54.

In addition, as shown in fig. 2, the sub guide roller 56 is supported by the outer periphery of one of the bosses 28A. A boss 28 is protrudingly formed on the left bearing wall 22L to fasten the separator member 26.

The one boss 28A supports the secondary guide roller shaft 58 of the secondary guide roller 56.

In addition, as shown in fig. 1, the inter-axis distance d1 and the inter-axis distance d2 are set equal to each other. The inter-axis distance d1 is a distance between the axis 51a of the camshaft 51 and the axis 57a of the guide roller shaft 57, and the inter-axis distance d2 is a distance between the axis 57a of the guide roller shaft 57 and the axis 58a of the sub-guide roller shaft 58 of the sub-guide roller.

Further, behind the drive sprocket 59 in the cam chain chamber 2c, the tension lever 80 of the cam chain tensioner 8 is swingably supported by the pivot bolt 81 at an intermediate portion of the tension lever 80 in a swingable manner.

The tension roller 82 is rotatably supported on a distal end of one arm of the tension lever 80 extending upward, and the other arm of the tension lever 80 extends downward, a free end thereof forming an abutment end 80 a.

The push rod 84 of the oil lock type tensioner lifter 83 abuts the abutment end 80a of the tension lever 80 and is pressed to function as the abutment end 80a, so that the tension roller 82 at the distal end of the upwardly extending arm presses the rear side rotating portion of the cam chain 54 from the outer peripheral side of the cam chain 54.

Therefore, the tension roller 82 of the cam chain tensioner 8 presses the cam chain 54 from the outer periphery of the cam chain 54 at a position slightly downstream of the crankshaft 21 and upstream of the guide roller 55 with respect to the traveling direction of the cam chain 54, thereby applying an appropriate tension to the cam chain 54.

The sub guide roller 56 is provided on the opposite side of the tension roller 82 with respect to the cam chain 54 (on the front side of the cam chain 54) and cooperates with the tension roller 82 to guide the cam chain 54 so as to press the cam chain 54 in the direction opposite to the direction in which the tension roller 82 presses the cam chain 54.

An oil pressure locking type tensioner lifter 83 is formed below the drive sprocket 59. The drive sprocket 59 is fixedly attached to the crankshaft 21, and the crankshaft 21 is rotatably supported by the left crankcase 2L.

Fig. 3 is a sectional view showing the configuration of the cam chain tensioner 8 as viewed along the line III-III in fig. 1.

Referring to fig. 1 and 3, fig. 3 shows a cross section taken on the line III-III of fig. 1, the left bearing wall 22L of the left crankcase 2L has a peripheral wall 24 connected thereto and extending to the left. A guide hole 85 for the oil pressure locking type tensioner lifter 83 extends through the peripheral wall 24 in an area below the crankshaft 21. The guide hole 85 extends from inside the space inside the peripheral wall 24 to outside the peripheral wall 24. The guide hole 85 in the oil pressure locking type tensioner lifter 83 extends obliquely so that the lower portion of the guide hole 85 is located on the front side. The guide hole 85 penetrates inside and outside the cam chain chamber 2c.

A part of the guide hole 85 of the oil pressure locking type tensioner lifter 83 in the upper portion of the peripheral wall 24 communicates with the oil reservoir 86 formed in the left bearing wall 22L, and the lower half of the guide hole 85 is formed in the guide pipe portion 87 extending obliquely downward from the peripheral wall 24.

The oil reservoir 86 is a recessed portion having an open upper portion. The left bearing wall 22L forms the right side wall of the oil reservoir 86, and lacks the left side wall thereof. Alternatively, the side wall panel 88 is attached to form the left side wall.

The upper opening of the guide hole 85 faces the oil reservoir 86. In other words, the oil pressure locking type tensioner lifter 83 is connected to the oil reservoir 86.

The oil pressure locking type tensioner lifter 83 has a push rod 84 inserted into a guide hole 85 from an upper opening and slidably supported in the guide hole 85.

The push rod 84 is a cylindrical member having an outer diameter slightly smaller than the inner diameter of the guide hole 85. Circular holes 84a are formed at a plurality of desired positions of the tubular wall of the push rod 84, and oil can be supplied from the oil reservoir 86 to the inside of the cylindrical push rod 84 through the circular holes 84 a.

A head member 89 made of rubber is fittingly attached to the upper end opening of the push rod 84.

A control valve 90 is disposed in the lower end opening of the push rod 84.

The control valve 90 has a valve seat 90a fitted in a slightly inner portion of the lower end opening of the push rod 84. The valve seat 90a has a bottom cylindrical shape in which a circular hole is bored, and the ball 90b is loosely fitted in the bottom cylindrical shape of the valve seat 90a so as to open and close the circular hole of the valve seat 90 a. A bonnet 90c fits in the opening of the valve seat 90a to prevent the ball 90b from falling out. The bonnet 90c has a bottom cylindrical shape with a circular hole drilled in the bottom wall of the bonnet 90 c.

The tension bolt 91 is screwed into the lower end of the guide tube portion 87, and closes the lower end opening of the guide hole 85.

The push rod 84 is inserted into the guide hole 85 from above, the push rod 84 including the control valve 90 is loaded at the lower end as described above, and the compression spring 92 is inserted into the guide hole 85 from below. Then, the lower end opening of the guide hole 85 is closed by the tension bolt 91, whereby the push rod 84 is pushed obliquely upward by the compression spring 92.

The head member 89 at the upper end of the push rod 84 abuts the abutment end 80a of the tension lever 80. Therefore, as shown in the side view of fig. 1, the push rod 84 pushed obliquely upward by the compression spring 92 swingably pushes the tension lever 80 counterclockwise about the pivot bolt 81. Therefore, the tension roller 82 at the other end of the tension lever 80 presses the rear side rotating portion of the cam chain 54, and a constant tension can be applied to the cam chain 54.

As described above, by connecting the oil reservoir 86 to the circular hole 84a of the inside of the push rod 84, the oil held in the oil reservoir 86 is supplied to the inside of the cylindrical push rod 84, and the oil fills the lower portion of the inside of the cylindrical push rod 84 and the inside of the oil chamber 85a, which is the portion of the guide hole 85 below the control valve 90 to which the compression spring 92 is loaded.

Therefore, although the push rod 84 is in a state of being pushed by the tensioner rod 80, the oil in the oil chamber 85a below the control valve 90 in the guide hole 85 presses the ball 90b to the circular hole of the valve seat 90a to hold the valve seat 90a in a closed state and prevent the push rod 84 from retracting (descending).

When the cam chain 54 is loosened, the push rod 84 is advanced by the urging force of the compression spring 92, swinging the tension lever 80, and pressing the tension roller 82 deeper against the cam chain 54 to maintain the tension.

At this time, the control valve 90 is opened, and the oil in the push rod 84 passes through the control valve 90 into the lower oil chamber 85a, so that the push rod 84 can advance.

The push rod 84, which has been advanced, cannot be retracted by closing the control valve 90, so the cam chain 54 is no longer slack and the proper tension can be constantly applied and maintained to the cam chain 54.

As shown in fig. 1, the oil guide rib 29 is arranged to project leftward from the left bearing wall 22L of the crankcase 2. The oil guide rib 29 is inclined downward to the rear in the region of the cam chain chamber 2c, below the sub guide roller 56 and the drive sprocket 59.

The lower end portion of the oil guide rib 29 extends to a region above the oil reservoir 86 as viewed in the crankshaft axial direction. The inclined oil guide ribs 29 receive oil droplets due to the rotation of the drive sprocket 59 and the sub guide roller 56, and due to the rotation of the cam chain 54 and the downward flow of oil along the surface of the left bearing wall 22L facing the cam chain chamber 2c. The inclined oil guide rib 29 then guides the oil downward to the rear, and the oil guided by the oil guide rib 29 and flowing downward to the lower end of the oil guide rib 29 is received by the oil reservoir 86. Therefore, the used oil can be effectively collected in the oil reservoir 86.

As described above, the cam chain guide device of the internal combustion engine 1 includes the driven sprocket 53, the guide roller 55, the cam chain tensioner 8, and the sub-guide roller 56. The driven sprocket 53 receives a rotational force from the crankshaft 21 through the endless cam chain 54 and rotates the camshaft 51. The guide roller 55 guides the cam chain 54 on the inner peripheral side of the cam chain 54. The cam chain tensioner 8 presses the cam chain 54 from the outer peripheral side of the cam chain 54 through the tension roller 82 to apply tension to the cam chain 54 in the cam chain extension between the crankshaft 21 and the guide roller 55. The sub guide roller 56 guides the cam chain 54 so as to press the cam chain 54 on the outer peripheral side of the cam chain 54 in the direction opposite to the direction in which the tension roller 82 presses the cam chain 54. In the above arrangement, the diameter of the guide roller 55 is equal to the diameter of the driven sprocket 53.

By making the driven sprocket 53 and the guide roller 55 have equal or same diameters, the movement of the cam chain 54 becomes smaller, and the swing of the cam chain 54 can be prevented. Here, the movement and swing of the cam chain 54 is a movement thereof in a direction orthogonal to the advancing direction of the cam chain between the driven sprocket 53 and the guide roller 55 on an imaginary plane P (refer to fig. 2) including the plane of the driven sprocket 53 and orthogonal to the central axis of the camshaft 51. Also, the cam chain 54 can be prevented from swinging.

The distance d1 between the axis 51a of the cam shaft 51 and the axis 57a of the guide roller shaft 57 of the guide roller 55 is equal to the distance d2 between the axis 57a of the guide roller shaft 57 and the axis 58a of the sub guide roller shaft 58 of the sub guide roller 56. This arrangement means that the elongation of the cam chain 54 between the driven sprocket 53 and the guide roller 55 and the elongation of the cam chain 54 between the guide roller 55 and the sub-guide roller 56 are equal to each other, so that the bias of the mounting portion caused by the deflection of the cam chain 54 can be suppressed.

Further, a separator member 26 is arranged in the crank case 2, the crankshaft 21 is inserted into the separator member 26, the separator member 26 separates the inside and the outside of the cam chain chamber 2c in the vehicle width direction and has a circular shape, and an opening center 25a of the circular opening portion 25 of the crank case 2 is arranged at a position eccentric to the axis 21a of the crankshaft 21, the separator member 26 is attached to the crank case 2.

Therefore, it is possible to change the distance from the axis 21a of the crankshaft 21 to the inner periphery 25b of the circular opening portion 25, without providing a member, such as the sub guide roller 56, disposed inside the circular opening portion 25 in the vehicle width direction in a constant range around the crankshaft 21, and the degree of freedom of layout in the crankcase 2 is improved.

In addition, the cam chain tensioner 8 includes an oil-pressure-locking type tensioner lifter 83 disposed in the left bearing wall 22L of the crankcase 2, a push rod 84 is inserted into the oil-pressure-locking type tensioner lifter 83, a tension roller 82 is pivotably supported by a tension lever 80, and the tension lever 80 is pushed and swung by the push rod 84.

The oil guide rib 29 is disposed in the crankcase 2, the oil guide rib 29 is disposed so as to project from the left bearing wall 22L, the left bearing wall 22L faces the cam chain chamber 2c, the lower end of the oil guide rib 29 extends above the oil reservoir 86 as viewed in the axial direction of the crankshaft, the oil reservoir 86 is disposed in the left bearing wall 22L, the left bearing wall 22L faces the cam chain chamber 2c, and the oil-pressure-locking tensioner lifter 83 is connected to the oil reservoir 86.

Therefore, the oil is efficiently supplied to the oil reservoir 86 by the oil guide rib 29, the oil guide rib 29 is disposed to project from the left bearing wall 22L, and the left bearing wall 22L faces the cam chain chamber 2c, so that oil shortage of the oil-pressure-locking-type tensioner lifter 83 can be prevented, the tension roller 82 can reliably operate, and the effect of suppressing the swing of the cam chain 54 by the guide roller 55 can be secured.

As described above, although the embodiments according to the present invention have been described, aspects of the present invention are not limited to the above-described embodiments, but include embodiments implemented in various modes within the scope of the claims of the present invention. For example, the internal combustion engine is not limited to the type in the embodiment, and the vehicle is not limited to a motorcycle, but may also include a three-wheeled and four-wheeled off-road vehicle, and the like.

Further, although explanation is made in the case where the internal combustion engine is specified to have the left-right layout shown in the embodiment for convenience of explanation, the invention also includes an internal combustion engine having a different left-right layout.

A list of reference numbers 51a.. axis,

an internal combustion engine, 53.

A crankcase, 53c.

2a.. an outer wall, 54.. a cam chain,

2c.

2l.. left crankcase, 55.. guide roller,

2r.. right crankcase, 55c.. center of rotation,

a transmission, 56.

A cylinder, 57.

An outer wall, 57a.

4c. cam chain cavity, 58.

A cylinder head, 58a.

5c. a cam chain cavity, 80.. a tensioning lever,

a cylinder head cover, 82.

A left housing cover, 83.. an oil pressure locking tensioner lifter,

a cam chain tensioner,

an alternator, 84.

A crank chamber, 86.

A crankshaft, p.. an imaginary plane, which includes the driven sprocket, and is orthogonal to the camshaft 51,

an axis of rotation of the shaft, the axis of rotation of the shaft,

21l.. left crankshaft portion, r53.. radial direction distance,

22l.. left bearing wall, r55.. radial direction distance,

a peripheral wall, d1.. an inter-axis distance,

circular opening portion, d2

25a. the center of the opening,

25b.. inner periphery,

in another aspect, a separator member for use in a medical device,

28a. a boss,

an oil-guiding rib of the oil-guiding structure,

a drive sprocket for use in a chain drive,

a camshaft.

Claims

1. A cam chain guide device for an internal combustion engine, comprising:

a crankshaft (21) of the engine (1);

a camshaft (51) of the valve train;

a driven sprocket (53) mounted on the camshaft (51) and receiving a rotational force from the crankshaft (21) through an endless cam chain (54) to rotate the camshaft (51) supported on a cylinder head (5);

a guide roller (55) supported in the cylinder (4) and disposed inside a path of the endless cam chain (54) to guide the cam chain (54);

a cam chain tensioner (8) that is provided on one side of the crankshaft (21) with respect to the guide roller (55), and that has a tension roller (82) to press the cam chain (54) from outside the path of the cam chain (54) so as to apply tension to the cam chain (54); and

a sub-guide roller (56) that is provided on the opposite side of the tension roller (82) with respect to the cam chain (54) and that cooperates with the tension roller (82) to guide the cam chain (54) so as to press the cam chain (54) in a direction opposite to a direction in which the tension roller (82) presses the cam chain (54);

wherein the diameter of the guide roller (55) is equal to the diameter of the driven sprocket (53);

wherein a portion of the guide roller (55) protrudes from an upper surface of the cylinder block (4) to be positioned in the cylinder head (5);

wherein an inter-axis distance (d1) between an axis (51a) of the camshaft (51) and an axis (57a) of the shaft (57) of the guide roller (55) and an inter-axis distance (d2) between the axis (57a) of the shaft (57) of the guide roller (55) and an axis (58a) of the shaft (58) of the sub-guide roller (56) are equal to each other.

2. A cam chain guide device for an internal combustion engine, comprising:

a crankshaft (21) of the engine (1);

a camshaft (51) of the valve train;

wherein the cam chain (54) passes in cam chain chambers (5c, 4c) defined in the cylinder head (5) and the cylinder block (4) and having front and rear surfaces formed as continuous surfaces along an imaginary axis connecting an axial center (51a) of the camshaft (51) and an axial center (57a) of a shaft (57) of the guide roller (55) from an upper end surface of the cylinder head (5) to a lower end surface of the cylinder block (4);

3. The cam chain guide device for an internal combustion engine according to claim 2,

the cam chain tensioner (8) includes an oil pressure locking type tensioner lifter (83) provided in a bearing wall (22L) of a crankcase (2), and a push rod (84) slidably inserted into the tensioner lifter (83);

the tension roller (82) is supported by a tension lever (80) pivotally supported in the crank case (2) so as to be pressed against the cam chain (54) by the push rod (84);

the oil reservoir (86) is provided in a bearing wall (22L) facing the cam chain chamber (2 c);

an oil guide rib (29) is provided in the crankcase (2) so as to project from a bearing wall (22L) facing a cam chain chamber (2c), a lower end portion of the oil guide rib (29) extending to a region above the oil reservoir portion (86) as viewed in an axial direction of the crankshaft; and is

The oil pressure locking type tensioner lifter (83) is communicatively connected to the oil reservoir (86).

4. The cam chain guide device for an internal combustion engine according to claim 1 or 2,

the portion of the cam chain (54) that extends forward of the cam shaft (51) and above the contact position of the cam chain (54) with the guide roller (55) is substantially parallel to the portion of the cam chain (54) that extends rearward of the cam shaft (51) and above the contact position of the cam chain (54) with the guide roller (55); and is

At least a portion of the cam chain (54) extending forward of the cam shaft (51) and below a contact position of the cam chain (54) with the guide roller (55) and a portion of the cam chain (54) extending rearward of the cam shaft (51) and below a contact position of the cam chain (54) with the guide roller (55) are inclined so as to approach each other as the two portions below the contact position extend downward.