CN120720117A - Engine with a motor - Google Patents

Abstract

The present invention provides an engine. A balancer can be compactly arranged at a position other than the front of the engine, making the engine more compact. An engine is provided, wherein a cam chain (67, 68) is provided on the side of the engine, and a cam chain drive sprocket (65, 66) driving the cam chain (67, 68) is driven by a cam chain drive gear (64) coaxially arranged on the side of the engine. The cam chain drive gear (64) is driven by an idle driven gear (63), and the idle driven gear (63) is driven by an idle driving gear (62) meshing with a predetermined gear (61) provided on a crankshaft (10). In the engine, a balancer (80) is coaxially arranged with the idle driving gear (62).

Description

Engine with a motor

Technical Field

The present invention relates to an engine.

Background

An engine configured by an internal combustion engine having a balancer for suppressing vibration is known. In such an engine, there is a structure in which a water pump shaft is fitted and fixed to one end portion of a front balance shaft (for example, refer to patent document 1).

Prior art literature

Patent literature

Patent document 1 Japanese patent application laid-open No. 2009-162202

Disclosure of Invention

Problems to be solved by the invention

When the balancer is disposed, there is a case where the balancer is provided with an auxiliary machine coaxially driven by the same driving source, but it is difficult to dispose the balancer compactly except for a portion having a high degree of freedom such as the front of the engine.

The present invention has been made in view of the above-described circumstances, and an object thereof is to compactly arrange a balancer even in a portion other than the front of an engine and to make the engine compact.

Means for solving the problems

The present invention provides an engine, a cam chain is arranged at the side of the engine, a cam chain driving sprocket for driving the cam chain is driven by a cam chain driving gear 64 coaxially arranged at the side of the engine, the cam chain driving gear is driven by an idle driven gear, the idle driven gear is driven by an idle driving gear meshed with a prescribed gear arranged at a crankshaft, and a balancer is coaxially arranged with the idle driving gear.

Effects of the invention

According to the present invention, the balancer can be compactly disposed even in a portion other than the front of the engine, and the engine can be compactly formed.

Drawings

Fig. 1 is a perspective view of an engine according to an embodiment of the present invention.

Fig. 2 is a cross-sectional view of the engine taken through the face of the crankshaft, main shaft and front cylinder.

Fig. 3 is a view showing the peripheral configuration of the idle gear support shaft and the cam chain drive shaft.

Fig. 4 is a perspective view showing a section of the crankshaft together with an idler gear support shaft and the like.

Fig. 5 is a perspective view showing a section of the idler gear support shaft together with a crankshaft or the like.

Fig. 6 is a perspective view showing the idler gear support shaft together with the peripheral configuration.

Fig. 7 is a view showing the cam chain drive shaft together with the peripheral configuration.

Description of the reference numerals

1, An engine (internal combustion engine);

10, a crankshaft;

10c, crank arm;

10d, crank pin;

10e, balancing the crankshaft;

11, a crank case;

12F, 12R are cylinders;

13, a valve driving mechanism;

17a, connecting rod big end;

21, a main shaft;

31 an idler gear support shaft;

31h, an oil supply hole;

33. 34, a bearing;

41 primary drive gear;

51, clutch mechanism;

timing gear 61;

an idler drive gear 62;

62s, a delay gear (backlash absorbing mechanism);

63, idling the driven gear;

64 cam chain drive gear;

A first cam chain drive sprocket 65;

a second cam chain drive sprocket 66;

67 a first cam chain;

a second cam chain 68;

71 balancer driving gear;

72 balancer driven gear;

80, balancer.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description, the directions of the front, rear, left, right, up and down are the same as the directions with respect to the vehicle body unless otherwise specified. Note that reference numeral "FR" shown in each figure indicates the front of the vehicle body, reference numeral "UP" indicates the upper part of the vehicle body, and reference numeral "LH" indicates the left part of the vehicle body.

Embodiment(s)

Fig. 1 is a perspective view of an engine 1 according to an embodiment of the present invention. The engine 1 shown in fig. 1 shows a state in which a crankcase cover 2 covering the engine 1 from the right side is detached.

The engine 1 is a V-type engine mounted on a motorcycle, and may be referred to as an internal combustion engine or a power unit. The engine 1 includes a crankcase 11 rotatably supporting a crankshaft 10, a front cylinder (also referred to as a first cylinder group) 12F extending forward and upward from an upper portion of the crankcase 11, and a rear cylinder (also referred to as a second cylinder group) 12R extending rearward and upward from an upper portion of the crankcase 11.

Each of the cylinders 12F and 12R includes a cylinder block 12a, a cylinder head 12b connected to an upper surface of the cylinder block 12a, and a cylinder head cover, not shown, that blocks the upper surface of the cylinder head 12b, and a valve train 13 is disposed between the cylinder head 12b and the cylinder head cover.

The crankcase 11 is a hollow case for supporting the crankshaft 10 and a peripheral structure, and is divided into left and right. However, the shape and structure of the crankcase 11 may be changed as appropriate according to the specifications of the engine 1, etc.

The crankshaft 10 is rotatably supported in the crankcase 11 in the vehicle width direction. A main shaft 21 is rotatably supported below and rearward of the crankshaft 10 in the crankcase 11, and a counter shaft 22 is rotatably supported below the crankshaft 10 and the main shaft 21. An idler gear support shaft 31 is rotatably supported by the crankcase 11 above and rearward of the crankshaft 10, and a cam chain drive shaft 32 is rotatably supported by the crankcase 11 above and rightward of the idler gear support shaft 31. The crankshaft 10, the main shaft 21, the counter shaft 22, the idler gear support shaft 31, and the cam chain drive shaft 32 are parallel to each other.

Fig. 2 is a cross-sectional view of the engine 1 taken through the crankshaft 10, the main shaft 21, and the front cylinder. The crankshaft 10 includes left and right journals 10a rotatably supported by the crankcase 11 and a crank 10b disposed between the left and right journals 10a and accommodated in the crank chamber 14. The crank 10b includes a crank arm 10c integrated with the journal 10a and a crank pin 10d connecting the crank arm 10c to each other.

The crank arm 10c is integrally provided with a crankshaft counterweight 10e on the opposite side of the crank pin 10d from the axial center of the crankshaft 10.

A cylinder block 12a above the crank chamber 14 is provided with a cylinder bore 15, and a piston 16 is provided in the cylinder bore 15. The piston 16 is coupled to the crankshaft 10 via a connecting rod 17.

The engine 1 of this configuration is configured such that the front and rear cylinders are different in phase, and the connecting rod large end portions 17a of the front and rear cylinders adjacent to each other on the crank pin 10d are adjacent to each other with the crank arm 10c interposed therebetween.

The right end portion (one) of the crankshaft 10 protrudes to the right of the crankcase 11, and a primary drive gear 41 is provided at the end portion. The primary drive gear 41 meshes with a primary driven gear 42 provided on the main shaft 21.

A transmission chamber 18 is provided at the rear of the crankcase 11, and a continuously engaged gear transmission 19 is accommodated in the transmission chamber 18. The transmission chamber 18 and the crank chamber 14 are partitioned by a partition wall 11 w.

The gear transmission 19 includes a main shaft 21 provided parallel to the crankshaft 10, a counter shaft 22 provided parallel to the main shaft 21, and a gear train group 19g provided to the main shaft 21 and the counter shaft 22. The counter shaft 22 functions as an output shaft of the engine 1, and drives rear wheels as drive wheels via a power transmission mechanism (e.g., a chain transmission mechanism).

A clutch mechanism 51 capable of shutting off power transmission between the crankshaft 10 and the power transmission mechanism is provided at the right end of the main shaft 21. The clutch mechanism 51 includes a clutch outer race 53 coupled to the primary driven gear 42 via a damper mechanism 52, a clutch inner race 54 fixed to the main shaft 21, and a friction plate 55 provided between the clutch outer race 53 and the clutch inner race 54. The clutch mechanism 51 is covered by the crankcase cover 2 from the vehicle width direction outer side. The crankcase cover 2 may also be referred to as a clutch cover.

As shown in fig. 2, a primary drive gear 41, a timing gear 61, and a balancer drive gear 71 are disposed at the right end of the crankshaft 10. These gears 41, 61, 71 are disposed in a space that is left free between the crankcase 11 and the crankcase cover 2.

The crankcase cover 2 includes a cylindrical portion 2t, and the cylindrical portion 2t protrudes inward of the engine so as to surround the periphery of the pipe 3 connected to the crankshaft 10. The space between the tubular portion 2t and the tube 3 is sealed by a sealing member 4, and an opening of the tubular portion 2t on the outer side in the vehicle width direction is closed by a cover 5.

Fig. 3 is a diagram showing the peripheral configuration of the idle gear support shaft 31 and the cam chain drive shaft 32.

The engine 1 employs a half cam gear system in which gears and cam chains are used in combination to drive the valve train 13 of the front and rear cylinders.

In the engine 1, rotation of the crankshaft 10 is transmitted to an idler drive gear 62 provided on the idler support shaft 31 via a timing gear 61 fixed to the crankshaft 10. Then, the rotation of the idler drive gear 62 is transmitted to a cam chain drive gear 64 provided on the cam chain drive shaft 32 via an idler driven gear 63 provided on the idler support shaft 31.

As shown in fig. 3, a first cam chain drive sprocket 65 for the rear cylinder and a second cam chain drive sprocket 66 for the front cylinder are fixed to the cam chain drive shaft 32. The valve train 13 of the rear cylinder (camshaft of the valve train 13) is driven by a first cam chain 67 wound around a first cam chain drive sprocket 65, and the valve train 13 of the front cylinder (camshaft of the valve train 13) is driven by a second cam chain 68 wound around a second cam chain drive sprocket 66. As shown in fig. 1 and 3, the structure for realizing the half cam gear system is concentrated on the right side of the engine.

Fig. 4 is a perspective view showing a cross section of the crankshaft 10 together with the idler gear support shaft 31 and the like. Fig. 5 is a perspective view showing a section of the idler gear support shaft 31 together with the crankshaft 10 and the like. Fig. 6 is a perspective view showing the idler gear support shaft 31 together with the peripheral structure.

As shown in fig. 4, a balancer drive gear 71 is fixed to the crankshaft 10 on the far right side (engine outside) of the crankshaft 10, a timing gear 61 is fixed to the balancer drive gear 71 on the inner side (engine inside) in the crankshaft direction, and a primary drive gear 41 is fixed to the timing gear 61 on the inner side (engine inside) in the crankshaft direction.

The number of teeth and the diameter of these gears 71, 61, 41 are appropriately set according to the specifications of the engine 1, and in the present embodiment, the primary drive gear 41 is formed as a gear having the largest diameter. Since the balancer drive gear 71 drives a balancer 80 described later to suppress one-time vibration of the engine 1, the balancer drive gear 71 drives the balancer 80 at the same rotational speed as the crankshaft 10 with a gear ratio of 1:1 between the balancer drive gear 71 and the crankshaft 10.

The timing gear 61 is a gear that decelerates the rotation of the crankshaft 10 to 1/2 and transmits to the valve train 13 (camshaft of the valve train 13). Therefore, the timing gear 61 is formed to be smaller in diameter than the balancer drive gear 71.

As shown in fig. 5, the idler gear support shaft 31 is a hollow shape with a bottom, which is separated from the crankcase 11, and is fixed to the crankcase 11 by a fastening member 31k inserted from the outside in the vehicle width direction in a state where the idler gear support shaft 31 is brought into contact with the crankcase 11 at the bottom. The fastening member 31k of the present embodiment is a single bolt. The structure of fixing the idler gear support shaft 31 to the crankcase 11 may be appropriately changed.

Two bearings 31a and 31b each constituted by a needle bearing are adjacently disposed on the idler gear support shaft 31. An idler driven gear 63 and an idler drive gear 62 that mesh with the timing gear 61 are mounted on the outer peripheral surface of the bearing 31a on the inner side in the crankshaft direction (corresponding to the inner side of the engine). Therefore, the idler driven gear 63 and the idler drive gear 62 are rotatable relative to the idler support shaft 31. These gears 63, 62 are rotated synchronously by being fixed to each other.

An idler gear 62s having the same diameter as the idler gear 62 is fitted to the idler gear 62 so as to be rotatable relative to each other. The intermediate gear 62s is engaged with the timing gear 61, and is biased in the opposite direction of the rotation direction of the timing gear 61 by the elastic member, absorbing backlash between the timing gear 61 and the idle drive gear 62. The intermediate wheel 62s is also called a scissor gear, and is an example of the "backlash absorbing mechanism" of the present disclosure.

A balancer driven gear 72 that meshes with the balancer drive gear 71 is attached to the outer peripheral surface of the bearing 31b on the outer side (corresponding to the outer side of the engine) of the idler gear support shaft 31 in the crankshaft direction.

A balancer 80 is integrally provided on the balancer driven gear 72. As shown in fig. 6, the balancer 80 is formed by forming a part of the balancer driven gear 72 into a fan-shaped thick portion that bulges to the right side of the engine (corresponding to the outer side in the crankshaft direction). The balancer 80 rotates (reverses) at the same rotational speed in synchronization with the crankshaft 10, thereby functioning as a primary balancer that suppresses primary vibration of the engine 1. By adjusting the shape and weight of the balancer 80, the vibration suppressing effect can be appropriately adjusted.

In addition, the construction of the balancer 80 is not limited to the above construction. For example, the balancer 80 may be made of a different component from the idler drive gear 62, and the balancer 80 and the idler drive gear 62 may be integrally connected to each other. Further, vibrations other than the primary vibration may be suppressed by adjusting the number of teeth of the gears of the balancer drive system, adjusting the balancer 80, or the like.

As shown in fig. 5, a plurality of oil supply holes 31h are provided in the idler gear support shaft 31. Lubricating oil is supplied into the idler gear support shaft 31, and the supplied lubricating oil is supplied to the bearings 31a and 31b and the gears 62 and 63 through the oil supply holes 31h.

As shown in fig. 3, a cam chain drive gear 64 is provided at the right end portion of the cam chain drive shaft 32, and the cam chain drive gear 64 is engaged with an idler driven gear 63 provided on the idler gear support shaft 31. The cam chain drive shaft 32 is provided with a second cam chain drive sprocket 66 for a front cylinder on the vehicle width direction inner side (corresponding to the engine inner side) of the cam chain drive gear 64, and a first cam chain drive sprocket 65 for a rear cylinder on the vehicle width direction inner side (corresponding to the engine inner side) of the second cam chain drive sprocket 66.

Fig. 7 is a view showing the cam chain drive shaft 32 together with the peripheral configuration.

As shown in fig. 7, the cam chain drive shaft 32, the cam chain drive gear 64, the first cam chain drive sprocket 65, and the second cam chain drive sprocket 66 are integrally manufactured.

Bearings 33 and 34 composed of rolling bearings are press-fitted to both ends of the cam chain drive shaft 32, and a first cam chain drive sprocket 65 is integrally formed on the cam chain drive shaft 32 at the outer periphery of the portion of the crank case 11 side where the bearing 33 is press-fitted. The cam chain drive gear 64 is integrally formed on the cam chain drive shaft 32 on the outer periphery of the portion of the crankcase cover 2 side in which the bearing 34 is pressed. The first cam chain drive sprocket 65, the second cam chain drive sprocket 66 and the cam chain drive gear 64 are coaxially disposed.

In this configuration, the cam chain drive shaft 32, the cam chain drive gear 64, the first cam chain drive sprocket 65, and the second cam chain drive sprocket 66 are integrally manufactured, so that the number of components can be reduced. Further, since the first cam chain drive sprocket 65 is provided by the portion pressed into the bearing 33, the first cam chain drive sprocket 65 can be disposed closer to the vehicle width direction inner side (engine inner side).

In this configuration, as shown in fig. 3, 5, and the like, the first cam chain drive sprocket 65 is disposed at a position overlapping the crankshaft counterweight 10e or the connecting rod large end portion 17a in the up-down direction perpendicular to the crankshaft direction. Thus, the first cam chain drive sprocket 65 and the first cam chain 67 can be disposed closer to the inside in the left-right direction of the engine 1. Therefore, the engine 1 can be made compact in the left-right direction (crankshaft direction).

As described above, in the engine 1 of the present embodiment, the crankshaft 10 is provided, the connecting rod large end portions 17a of the front and rear cylinders adjacent to each other on the crank pin 10d of the crankshaft 10 are adjacent to each other with the crank arm 10c interposed therebetween, and the cam chains 67, 68 are provided on one of the front and rear cylinders 12F, 12R on the engine side. The cam chain drive sprockets 65 and 66 that drive the cam chains 67 and 68 are driven by a cam chain drive gear 64 coaxially arranged on the engine side. The cam chain drive gear 64 is driven by the idler driven gear 63, and the idler driven gear 63 is driven by the idler drive gear 62 that meshes with the drive gear of the crankshaft 10.

As shown in fig. 3,5, and the like, in the present embodiment, the first cam chain drive sprocket 65 of the cam chain drive sprockets 65, 66 is disposed at a position overlapping the crankshaft counterweight 10e or the connecting rod large end portion 17a in the engine vertical direction perpendicular to the crankshaft direction, so that the first cam chain drive sprocket 65 and the first cam chain 67 can be disposed close to the left and right inner sides of the engine 1, and the engine 1 can be made compact in the width direction.

As shown in fig. 3 and 5, the idler drive gear 62 and the idler driven gear 63 rotate synchronously, and the idler drive gear 62 and the idler driven gear 63 rotate relative to the idler gear support shaft 31 that supports these gears 62, 63, and the idler gear support shaft 31 is fixed to the crankcase 11 of the engine 1.

According to this configuration, since there is no need to provide a bearing between the idler gear support shaft 31 and the crankcase 11, the circumference of the idler gear support shaft 31 can be miniaturized.

The idler gear 62 is provided with a counter wheel 62s functioning as a backlash absorbing mechanism. According to this structure, the backlash absorbing mechanism can be compactly provided.

The idler gear support shaft 31 is hollow with a bottom, the idler gear support shaft 31 is fixed to the crankcase 11 with the bottom portion thereof abutting against the crankcase 11, and the idler gear support shaft 31 includes an oil supply hole 31h for supplying oil from inside to the idler drive gear 62 and the idler driven gear 63. According to this structure, the lubrication structure of the gear provided on the idler gear support shaft 31 can be compactly provided.

Further, an oil supply hole 31h may be provided for supplying oil to at least one of the idler driving gear 62 and the idler driven gear 63.

As shown in fig. 1, the idler gear support shaft 31 is disposed between the crankshaft 10 and the main shaft 21 provided parallel to the crankshaft 10 in a side view of the engine. According to this structure, the space between the crankshaft 10 and the main shaft 21 can be effectively utilized, and the idler gear support shaft 31 can be compactly arranged.

As shown in fig. 5, the engine is provided with a primary drive gear 41 for transmitting the rotation of the crankshaft 10 to the main shaft 21, and the primary drive gear 41 is disposed on the engine inner side of the idle driven gear 63. According to this configuration, the primary drive gear 41 can be disposed closer to the engine inside, so that the torque applied to the crankshaft 10 can be reduced, and the circumference of the crankshaft 10 can be made compact.

The first cam chain drive sprocket 65, the second cam chain drive sprocket 66, and the cam chain drive gear 64 are coaxial and are provided as an integral member, the bearings 33 and 34 are press-fitted at both ends of the integral member, and the first cam chain drive sprocket 65 is formed on the outer periphery of the portion of the integral member on the crankcase 11 side where the bearing 33 is press-fitted. According to this structure, the components having the cam chain drive sprockets 65, 66 and the cam chain drive gear 64 can be easily formed compactly in the axial direction, which is advantageous in shortening the width of the engine 1.

As shown in fig. 3, the engine 1 of the present embodiment is provided with cam chains 67 and 68 on the engine side, and cam chain drive sprockets 65 and 66 for driving the cam chains 67 and 68 are driven by a cam chain drive gear 64 coaxially arranged on the engine side. The cam chain drive gear 64 is driven by an idler driven gear 63, and the idler driven gear 63 is driven by an idler drive gear 62 that meshes with a timing gear 61 (a predetermined gear) provided to the crankshaft 10. The balancer 80 is disposed coaxially with the idler drive gear 62.

According to this configuration, the balancer 80 can be compactly disposed even in a portion other than a portion having a high degree of freedom in front of the engine, and the engine 1 can be compactly configured.

In addition, the idler driven gear 63 and the idler driving gear 62 rotate synchronously and relatively to the idler gear support shaft 31 supporting these gears, and the balancer 80 relatively rotates to the idler gear support shaft 31 and rotates at a different rotational speed from the idler driving gear 62. According to this configuration, the balancer 80 can be disposed coaxially with the idler drive gear 62, and the rotational speed can be set independently in the cam chain drive system including the idler drive gear 62 and the balancer drive system, so that the degree of freedom in design of each drive system can be ensured.

Further, a balancer driven gear 72 driven by a balancer driving gear 71 provided on the crankshaft 10 is provided, and a balancer 80 is integrally provided on the balancer driven gear 72. According to this configuration, since the balancer drive gear 71 dedicated to the balancer is provided, the setting of the number of teeth can be changed in the balancer drive system and the cam chain drive system, and the degree of freedom of the gear ratio of each drive system can be improved. In addition, the balancer 80 is integrated with the balancer driven gear 72, and therefore, reduction in the number of parts and miniaturization are facilitated.

The balancer 80 is disposed on the outer side in the crankshaft direction, i.e., on the outer side of the engine with respect to the idler drive gear 62. According to this configuration, the cam chain drive system including the idler drive gear 62 can be disposed inside the engine, and the engine 1 can be made compact. When the specification of the balancer 80 is changed to a specification without the balancer 80, the layout inside the engine 1, for example, the layout of the cam chain driving system does not need to be changed significantly.

As shown in fig. 3 and 5, the balancer 80 and the clutch mechanism 51 overlap each other in a direction perpendicular to the crankshaft direction in a cross-sectional view in which the axis of the crankshaft 10 and the axis of the clutch mechanism 51 (corresponding to the axis of the main shaft 21) are cut off by a plane, and the clutch mechanism 51 is provided to cut off the power transmission from the crankshaft 10. According to this configuration, the balancer 80 can be disposed in the clutch mechanism 51 using the space left in the direction perpendicular to the crankshaft direction, and the balancer 80 can be disposed compactly.

The idler driven gear 63 is disposed on the outer side in the crank direction, i.e., the engine outer side, than the primary drive gear 41 provided in the crankshaft 10, and the balancer driven gear 72 is disposed on the outer side in the crank direction, i.e., the engine outer side, than the idler driven gear 63. According to this configuration, when the specification of the balancer 80 is changed and the specification of the balancer 80 is changed to be not changed, there is no need to greatly change the layout of the inside of the engine 1, for example, the layout of the drive system including the primary drive gear 41 and the layout of the drive system including the idler driven gear 63.

Other embodiments

The above-described embodiment merely shows one embodiment of the present invention, and can be arbitrarily modified and applied within a range not departing from the gist of the present invention.

For example, in the above embodiment, the case where the first cam chain drive sprocket 65 is disposed at a position overlapping the crankshaft counterweight 10e or the large end portion 17a in the up-down direction of the engine has been described, but the present invention is not limited to this, and the second cam chain drive sprocket 66 may be disposed at a position overlapping the crankshaft counterweight 10e or the large end portion 17a in the up-down direction of the engine. Further, both the first cam chain drive sprocket 65 and the second cam chain drive sprocket 66 may be disposed at positions overlapping the crankshaft counterweight 10e or the connecting rod large end portion 17a in the vertical direction of the engine.

In the above embodiment, the case where the balancer 80 is arranged coaxially with the idler drive gear 62 in the V-shaped engine 1 shown in fig. 1 and the like has been described, but the present invention is not limited to this, and the balancer 80 may be arranged coaxially with the idler drive gear 62 in an engine other than the V-shaped engine.

The present invention is described as being applied to the engine 1 mounted on the motorcycle, but the present invention is not limited to this, and may be applied to an engine mounted on a saddle-type vehicle other than the motorcycle, a vehicle other than the saddle-type vehicle, a moving body other than the vehicle, or the like.

[ Structure supported by the above embodiment ]

The above embodiment supports the following structure.

An engine according to an embodiment 1 is provided with a cam chain on the side of the engine, wherein a cam chain drive sprocket for driving the cam chain is driven by a cam chain drive gear coaxially arranged on the side of the engine, the cam chain drive gear is driven by an idler driven gear which is driven by an idler drive gear engaged with a predetermined gear provided on a crankshaft, and a balancer is arranged coaxially with the idler drive gear.

According to this configuration, the balancer can be compactly disposed, and the engine can be compactly configured.

(Structure 2) in the engine of structure 1, the idler driven gear rotates in synchronization with the idler driving gear, and the idler driven gear and the idler driving gear rotate relative to an idler gear support shaft that supports the idler driving gear and the idler driven gear, and the balancer rotates relative to the idler gear support shaft and rotates at a different rotational speed from the idler driving gear.

According to this configuration, the balancer can be arranged coaxially with the idler drive gear, and the rotational speed can be set independently in the cam chain drive system including the idler drive gear and the balancer drive system, so that the degree of freedom in design of each drive system can be ensured.

(Structure 3) in the engine of structure 1 or 2, the engine has a balancer driven gear that is driven by a balancer drive gear provided to the crankshaft, the balancer being integrally provided to the balancer driven gear.

According to this configuration, since the balancer drive gear dedicated to the balancer is provided, the setting of the number of teeth can be changed in the balancer drive system and the cam chain drive system, and the degree of freedom of the gear ratio of each drive system can be improved. In addition, the balancer is integrated with the balancer driven gear, so that the reduction in the number of parts and miniaturization are facilitated.

(Structure 4) in the engine of any one of structures 1 to 3, the balancer is arranged outside the engine with respect to the idler drive gear.

According to this configuration, the cam chain drive system including the idler drive gear can be disposed inside the engine, and the engine can be made compact. In addition, when the balancer is changed in specification to a specification without the balancer, the layout inside the engine does not need to be changed significantly.

(Configuration 5) in the engine according to any one of configurations 1 to 4, the engine includes a clutch mechanism that cuts off power transmission from the crankshaft, and the balancer and the clutch mechanism overlap in a direction perpendicular to a direction of the crankshaft in a cross-sectional view that cuts an axial center of the crankshaft and an axial center of the clutch mechanism in a plane.

According to this configuration, the balancer can be disposed in the clutch mechanism using the space left in the direction perpendicular to the crankshaft direction, and the balancer can be disposed compactly.

(Configuration 6) in the engine of configuration 3, the idler driven gear is disposed on the engine outer side of a primary drive gear provided on the crankshaft, and the balancer driven gear is disposed on the engine outer side of the idler driven gear.

According to this configuration, when the balancer is changed in specification and the balancer is changed to the specification without the balancer, the layout inside the engine does not need to be changed significantly.

Claims (6)

1. An engine, wherein,

A cam chain (67, 68) is provided on the side of the engine, cam chain drive sprockets (65, 66) for driving the cam chain (67, 68) are driven by a cam chain drive gear (64) coaxially arranged on the side of the engine, the cam chain drive gear (64) is driven by an idler driven gear (63), the idler driven gear (63) is driven by an idler drive gear (62) which meshes with a predetermined gear (61) provided on the crankshaft (10),

Wherein, the

A balancer (80) is disposed coaxially with the idler drive gear (62).

2. The engine of claim 1, wherein,

The idler driven gear (63) rotates in synchronization with the idler driving gear (62), and the idler driven gear (63) and the idler driving gear (62) rotate relative to an idler gear support shaft (31) supporting the idler driving gear (62) and the idler driven gear (63),

The balancer (80) rotates relative to the idler gear support shaft (31) and rotates at a different rotational speed from the idler drive gear (62).

3. The engine of claim 1, wherein,

The engine has a balancer driven gear (72), the balancer driven gear (72) is driven by a balancer driving gear (71) provided to the crankshaft (10),

The balancer (80) is integrally provided to the balancer driven gear (72).

4. The engine of claim 2, wherein,

The balancer (80) is disposed outside the engine with respect to the idler drive gear (62).

5. The engine of claim 2, wherein,

The engine is provided with a clutch mechanism (51) for cutting off the power transmission from the crankshaft (10),

In a cross-sectional view of the shaft center of the crankshaft (10) and the shaft center of the clutch mechanism (51) in a plane, the balancer (80) overlaps the clutch mechanism (51) in a direction perpendicular to the direction of the crankshaft (10).

6. The engine according to claim 3, wherein,

The idle driven gear (63) is disposed at a position outside the engine than a primary drive gear (41) provided on the crankshaft (10),

The balancer driven gear (72) is disposed on the outside of the engine from the idle driven gear (63).