JPH0621569B2 - Rotational force transmission device for motorcycle drive system and balancer shaft - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a V-type engine having a common crank pin for a set of V-shaped cylinders and having a included angle of less than 90 °, in which a crankshaft is connected to a balancer shaft and a drive system. The present invention relates to a power transmission device.

Conventionally, in a V-type engine with a cylinder included angle of 90 °,
The crankpin was shared by one set of cylinders arranged in a V shape, and the balance weight attached to the crank eliminated the residual unbalanced inertial force primary term of the reciprocating mass of the piston, etc.
In the case of a compact engine with a cylinder included angle of 90 ° or less, the balance weight formed on the crank cannot eliminate the primary term of the residual unbalanced inertial force, resulting in engine vibration. Was transmitted to the motorcycle body and the riding comfort was poor.

A motorcycle engine equipped with a balancer has been conceived to overcome the above-mentioned difficulties, but the present invention provides a balancer equipped with such a balancer, in which the length of the crankshaft is shortened to reduce the lateral side of the vehicle body. In an attempt to shorten the width and make the engine compact, the balancer shaft is rotatably mounted in front of the crankshaft in parallel with it, and the gear arranged at one end of the crankshaft meshes with the gear of the drive system. The gear is fixed to the balancer shaft and is meshed with the gear. The rotation of the crankshaft is transmitted to the drive system and the balancer shaft by one gear fixed to the crankshaft.

An embodiment of the present invention shown in the drawings will be described below.

Reference numeral 1 is a motorcycle, in which the crankshaft 4 of a 4-cylinder V-type 4-cycle gasoline engine 3 is oriented in the width direction of the vehicle body, and the cylinder 6 is a V-type with a front-back angle of 70 °. The engine 3 is mounted on the frame 2 of the wheeled vehicle 1.

Then, the four cylinder V type four cycle gasoline engine 3
In the cylinder sets 6a and 6b and the cylinder sets 6c and 6d arranged in a V-shape in the front and rear, the crank pins 5a and 5b are common, and the front cylinders 6a and 6c are the rear cylinders 6b and 6d.
Each is slightly offset to the right.

In the crankcase 7, a balancer 8 is rotatably supported in front of the crankshaft 4 in parallel therewith, and the gears 11 and 12 having the same pitch circle and the same number of teeth are meshed with each other. 4 and the right end of the shaft 9 of the balancer 8 are integrally fitted to the balancer 8 respectively.
The balance weights 10a and 10b of the crank pins 5a and 5b are
The balance weight is installed on the same vertical plane as
The gears 11, 10a, 10b have an angular relationship such that the first-order term of the residual unbalanced inertial force of the reciprocating mass in the engine 3 is eliminated.
Twelve meshed.

The gear 12 is attached to the balancer shaft 9 by a nut 19, and the gear 11 is also a drive gear for the drive system as described later.

Further, sprockets 13a and 13b are integrally formed substantially at the center of the crankshaft 4, and cam sprockets 16 are attached to cam shafts 15a and 15b that are rotatably supported by the front cylinder head 14a and the rear cylinder head 14b, respectively.
a and 16b are fitted together, and a cam chain 17 is attached to each of the sprockets 13b and 13a and the cam sprockets 16a and 16b.
a and 17b are bridged, and the rotation of the crankshaft 4 is transmitted to the camshafts 15a and 15b via the sprockets 13b and 13a, the cam chains 17a and 17b, and the cam sprockets 16a and 16b. Is driven to open and close.

Furthermore, an AC generator 18 is arranged at the left end of the crankshaft 4.

Further, the gear 11 fitted to the right end of the crankshaft 4 also serves as a drive gear of the drive system, and the main shaft 20 and the countershaft 21 are rotatably supported in the rear of the crankshaft 4 in parallel therewith. The input gear 23 of the clutch 22 pivotally mounted on the main shaft 20 is meshed with the gear 11.

Further, the output portion (not shown) of the clutch 22 is directly connected to the main shaft 20, the main shaft gear group 24 is spline-fitted or fitted to the main shaft 20, and the counter shaft gear group 25 is splined to the counter shaft 21. The main shaft gear group 24 is selectively engaged with any gear of the counter shaft gear group 25 by a shift fork (not shown) so that a predetermined reduction ratio is achieved. The counter shaft 21 and the drive sprocket 26 integrated with the counter shaft 21 are rotationally driven.

Furthermore, the final driven sprocket 28 is integrally fitted to the rear wheel 27, and the drive sprocket is
A drive chain 29 is provided between the 26 and the final driven sprocket 28.

Moreover, the crankcase 7 has a split surface that passes through the crankshaft 4, the main shaft 20 and the countershaft 21, and is vertically divided into two parts.
It is divided and connected to each other with bolts 31.

The crankshaft 4 and the balancer shaft 9 are respectively provided with a plurality of bearing portions 34a, which are provided on the split surface of the crankcase 7.
It is supported by 34b, 38a, 38b and a pair of bearings 35a, 35b. The bearings 38a, 38b in the center are ribs 3 from the front of the case.
It is reinforced by extending 9a and 39b.

The balancer shaft 9 has one bearing portion 35a inside the one bearing portion 35a.
A protrusion 36 having a larger diameter is formed, and after the balancer shaft 9 is placed on the bearing portion 35a, the bearing portion 35a is formed between the balancer shaft 9 and the protrusion 36.
A nut 37 is screwed from the outside of the balancer shaft 9 so as to hold the balancer shaft 9, and the balancer shaft 9 is attached to the bearing portion 35a so that the movement in the axial direction is restricted. The protrusion 36 may be a bulge or a flange that supports another member such as a gear.

Further, side covers 32, 33 are detachably fitted on both sides of the crankcase 7.

Since the illustrated embodiment is configured as described above, the output of the engine 3 is from the drive gear 11 integrated with the crankshaft 4 to the input gear 23 of the clutch 22, the clutch 22, the main shaft 20, the main shaft gear group 24. , The counter shaft gear group 25, the counter shaft 21, the drive sprocket 26, and the drive chain 29 to the final driven sprocket 28, and the rear wheel 27 is driven.

Further, as a result of setting the cylinder included angle to 70 °, even if the crank weight 30 formed integrally with the crank shaft 4 cannot eliminate the first-order term of the residual unbalanced inertial force of the reciprocating mass in the engine 3, The balancer 8 connected to the crankshaft 4 can eliminate the first-order term of the residual unbalanced inertial force, and the riding comfort can be improved.

In addition, since the rear wheel 27 is driven by the drive chain 29, the drive chain 29 functions as a damper (or a cushioning member), and the residual unbalanced inertial force after the second term also affects the riding comfort. Have contributed. Needless to say, the drive chain 29 is not limited to the drive chain 29 as long as it has a damper function.

Furthermore, the cylinders 6 are arranged in the front and rear in a V shape to reduce the dimension in the width direction, and the cylinder included angle is set to 70 °.
The width and front-rear length of the motorcycle 3 can be shortened to make the engine 3 compact, and thus the motorcycle 1 can be made compact and lightweight.

Further, since the rotational force is transmitted from the crankshaft 4 to the drive system and the balancer shaft 9 by one gear 11 without disposing two gears individually on the crankshaft,
Therefore, the length of the crankshaft 4 can be shortened and the width of the vehicle body can be shortened.

Furthermore, since the balancer 8 is located below the front cylinders 6a and 6c and in front of the crankshaft 4, the front-rear length of the engine 3 does not change even if the balancer 8 is attached.

In addition, the sprockets 13a, 1
3b is integrally formed, and the cam sprockets 16a, 16b and the cam chains 17a, 17b of the front cylinders 6a, 6c and the rear cylinders 6b, 6d are arranged substantially in the center in the width direction of the engine 3, so that the appearance of the engine 3 is left and right. It is not emphasized that there is a discrepancy between the front and back, and the noise can be suppressed as much as possible by moving the cam chain, which is a noise source, inward.

Further, a gear 11, which connects the crankshaft 4 and the balancer shaft 9,
Since the 12 is arranged on one side of the engine 3, the assembling property and the maintainability are improved.

Since the balancer shaft 9 is attached to the one bearing portion 35a so that the movement in the axial direction is restricted, the balancer shaft 9 may simply be placed on the other bearing portion 35b.

Further, since the crankcase 7 is vertically divided into two parts, and at least the crankshaft and the balancer shaft 9 are supported by the bearing portion formed on the split surface, the crankcase 7 is divided into the left and right parts and supported. In comparison with the above, the balancer shaft 9 and the like can be stably supported during assembly, and the assemblability is significantly improved.

The movement of the balancer shaft 9 in the axial direction is determined by the one bearing portion 35.
The bearing part 3 is formed by the protrusion 36 and the nut 37 formed on the inside of a.
It is possible to surely regulate by a simple configuration of holding 5a, and it is not necessary to take measures for preventing movement by another member. Therefore, the balancer shaft 9 only needs to be mounted on the other bearing portion 35b, and no structure for preventing movement is required, so that the degree of freedom of design in the vicinity of the bearing portion can be increased.

Since the present invention has the above-described structure, the balancer can eliminate the first-order term of the residual unbalanced inertial force and improve the riding comfort, and in addition to the crankshaft, the drive system and the balancer can be used. Since the rotation force is transmitted to the shaft with a single gear, the length of the crankshaft can be shortened, which helps to make the engine more compact, which in turn reduces the width of the vehicle body. The size and weight can be reduced.

Further, since the gear that connects the crankshaft with the drive system and the balancer shaft and the gear that is fixed to the balancer shaft that meshes with the gear are arranged on one end side of the crankshaft and the balancer shaft, respectively, the engine can be easily assembled and maintainability is improved. Can be improved.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of a balancer for a motorcycle engine according to the present invention, FIG. 2 is an enlarged view of an essential part thereof, and FIG. 3 is a partially longitudinal side view thereof. 1 ... Motorcycle, 2 ... Frame, 3 ... 4-cylinder V-type 4-cycle gasoline engine, 4 ... Crankshaft, 5 ...
… Crank pin, 6 …… Cylinder, 7 …… Crank case, 8 …… Balancer, 9 …… Balancer shaft, 10 …… Balance weight, 11 …… Gear, 12 …… Gear, 13 …… Sprocket, 14 …… Cylinder head, 15 ... Cam shaft, 16
…… Cam sprocket, 17 …… Cam chain, 18 …… AC generator, 19 …… Nut, 20 …… Main shaft, 21 ……
Counter shaft, 22 …… clutch, 23 …… input gear,
24 …… Main shaft gear group, 25 …… Counter shaft gear group, 26 …… Drive sprocket, 27 …… Rear wheel, 28 …… Final driven sprocket, 29 ……
Drive chain, 30 …… Crank weight, 31 …… Bolt, 32 …… Side cover, 33 …… Side cover, 34 ……
Bearing, 35 ... Bearing, 36 ... Projection, 37 ... Nut,
38 …… Bearing part, 38 …… Rib.

Claims (1)

[Claims] 1. A crankshaft is oriented in the width direction, cylinders are arranged in a V-shape at a cylinder included angle of less than 90 ° in the front-rear direction, and a crankpin is common to a pair of cylinders arranged in the V-shape. In a motorcycle engine, a balancer shaft is rotatably mounted in front of the crankshaft in parallel with the crankshaft, and a gear arranged at one end of the crankshaft is meshed with a gear of a drive system and the balancer shaft is engaged. A rotational force transmission device for a drive system and a balancer shaft of an engine for a motorcycle, characterized by being engaged with a gear fixedly mounted on.