JPH0886332A - Crank balancer driving device for engine - Google Patents

Abstract

PURPOSE: To provide a crank balancer driving device for an engine which can reduce tooth noises of gears without increasing a cost. CONSTITUTION: In a crank balancer device 30 for an engine, a balancer driven gear 29 of a balancer shaft 26 is interlockingly rotated by means of a balancer drive gear 24 of a crank shaft 15, for eliminating vibration at the operation of the engine. One of the balancer drive gear 24 and the balancer driven gear 29 is divided into an inner flange 31 fixed to the shaft 26 and a doughnut-like outer flange 32 rotatably arranged thereon in a relative manner. A limiter device 33 is arranged on a portion of sliding surfaces of the flanges. The device 33 rotates the flanges integrally at the stable rotation of the engine. Rotation of the crank shaft 15 is transmitted to the balancer shaft 26. When excessive torque is applied to the outer flange 32, the rotation of the crank shaft 15 is not transmitted to the balancer shaft 26.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crank balancer driving device for an engine.

[0002]

2. Description of the Related Art For example, in a single-cylinder or two-cylinder (especially narrow-angle V-type two-cylinder) four-cycle engine used for a motorcycle, primary vibration is likely to occur due to reciprocating motion of a piston. Therefore, some engines have a crank balancer for removing this primary vibration.

As shown in FIG. 7, the crank balancer 1
Is formed by fixing a balancer weight 2 in the shape of, for example, a fan, which corresponds to the total mass of a piston, connecting rod, etc., to a balancer shaft 3, and a balancer driven gear 4 provided on this balancer shaft 3 to a crankshaft 5
The balancer drive gear 6 and the like provided in the engine were interlocked to rotate to remove vibrations during engine operation.

When the engine is idling, the acceleration / deceleration is rapidly performed due to the fluctuation of the rotation, and the balancer drive gear 6 and the balancer driven gear 4 may generate a rattling noise.

Therefore, as shown in FIG. 7, an inner flange 7 having a balancer driven gear 4 fixed to the balancer shaft 3 and a donut-shaped outer flange 8 rotatably provided on the inner flange 7. And a damper device 9 such as a plurality of springs 9a and rubber 9b is provided on the sliding contact surfaces of both flanges 7 and 8, and both flanges 7 and 8 are integrally rotated by the damper device 9 during stable rotation of the engine. Further, the damper device 9 absorbs the rotational fluctuation during idling.

Further, although not shown, there is a balancer driven gear provided with a scissors gear.

[0007]

However, a damper device such as a spring or rubber is not sufficient to absorb the fluctuation in rotation at the time of engine idling, and the structure is complicated and costly.

Further, in the scissors gear, there are drawbacks that the cost is high and that a beating noise is generated when the force for pinching the teeth is increased.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an engine crank balancer driving device which is inexpensive and has a simple structure to reduce the rattling noise between gears. And

[0010]

In order to solve the above-mentioned problems, an engine crank balancer drive device according to the present invention is provided with a balancer drive gear or the like provided on a crankshaft as described in claim 1. The balancer driven gear provided on the balancer shaft is interlocked to rotate,
In a crank balancer drive device for an engine that eliminates vibrations during engine operation, one of the balancer drive gear and the balancer driven gear is fixed to the shaft, and an inner flange fixed to the inner flange is relatively rotatable. It is divided into a donut-shaped outer flange provided, and a limiter device is provided at one place of the sliding contact surface of both flanges, and this limiter device integrally rotates both flanges during stable rotation of the engine. The rotation of the crankshaft is transmitted to the balancer shaft, while the rotation of the crankshaft is not transmitted to the balancer shaft when an excessive torque is applied to the outer flange.

[0011]

According to the present invention having the above-described structure, the crank balancer drive of the engine for removing the vibration during engine operation by interlocking the balancer drive gear provided on the crankshaft with the balancer driven gear provided on the balancer shaft. Any one of the balancer drive gear and the balancer driven gear of the device is divided into an inner flange fixed to the shaft and a donut-shaped outer flange rotatably provided on the inner flange. A limiter device is provided at one place on the sliding contact surfaces of both flanges, and the limiter device integrally rotates both flanges when the engine is stably rotating, and transmits the rotation of the crankshaft to the balancer shaft. If excessive torque is applied to the outer flange, Since the rotation of the crankshaft is not transmitted to the balancer shaft, when the torque of the crankshaft is excessively applied to the gear, the outer flange idles, which does not cost much, and the gears have a simple structure. Toothing noise can be reduced.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a partial sectional view showing an example of an engine to which the present invention is applied.

The engine 11 is mainly composed of a crankcase 12, a cylinder 13 and a cylinder head 14. The crankshaft 1 is in the crankcase 12.
5 are arranged and supported in the crankcase 12 by a pair of bearings 16. The crankshaft 15 is divided into, for example, left and right parts, and is connected and integrated by a crankpin 17. A large end portion of a connecting rod 18 is connected to the crank pin 17, and the connecting rod 18 is connected.
A piston 20 is connected to a small end of the piston via a piston pin 19. And this piston 20 is the cylinder 13
The reciprocating stroke is transmitted to the crankshaft 15 via the connecting rod 18 to rotate the crankshaft 15.

The left end of the crankshaft 15 in the drawing projects into the magneto chamber 21, and the magneto 22 is attached to the end thereof.
Is provided. The magneto chamber 21 is covered with a magneto cover 23.

On the other hand, a balancer drive gear 24 is fixed to the crankshaft 15 so as to rotate integrally with the crankshaft 15 on the right end side in the figure.

FIG. 2 is a sectional view taken along the line II-II of FIG. As shown in FIGS. 1 and 2, a crank balancer 25 is arranged below the crankshaft 15 in the drawings. Balancer shaft 2 of crank balancer 25
6 is a crankcase 12 with a pair of bearings 27.
It is supported in parallel with the crankshaft 15. Also,
A fan-shaped balancer weight 28 corresponding to the total mass of the piston 20, the connecting rod 18, etc. is fixed to the left end of the balancer shaft 26 in the figure, while the balancer driven gear 2 is attached to the right end of the balancer shaft 26.
9 is provided, and the balancer driven gear 29 and the balancer drive gear 24 are operatively connected to form a crank balancer drive device 30. The balancer driven gear 29 and the balancer drive gear 24 may be operatively connected by a chain.

As shown in FIG. 2, the balancer driven gear 29 is an inner flange 3 fixed to the balancer shaft 26.
1 and a donut-shaped outer flange 32 rotatably provided on the inner flange 31. Further, a limiter device 33 is provided at one place of the sliding contact surfaces of the flanges 31 and 32. This limiter device 3
3 is a pin accommodating portion 34 provided on the outer peripheral surface of the inner flange 31 and a concave portion 35 provided on the inner peripheral surface of the outer flange 32.
And a limiter pin 36 provided in the pin housing 34
And the limiter pin 36 to the recess 35 of the outer flange 32.
It is composed of a spring 37 which is pressed toward.

In this limiter device 33, for example, the limiter pin 36 has the outer flange 3 when the engine 11 is rotating stably.
The flanges 31 and 32 are integrally rotated by engaging with the recess 35 of the second shaft, and the rotation of the crankshaft 15 is transmitted to the balancer shaft 26. Further, when the engine 11 is idling, sudden acceleration / deceleration occurs due to fluctuations in rotation, and the outer flange 32
When excessive torque is applied from the balancer drive gear 24, the limiter pin 36 is disengaged from the recess 35 of the outer flange 32, and the rotation of the crankshaft 15 is not transmitted to the balancer shaft 26. The outer flange 32, from which the limiter pin 36 is disengaged from the recess 35, makes one revolution around the outer circumference of the inner flange 31, and then engages with the inner flange 31 again by the limiter pin 36.

As shown in FIGS. 3 (a) and 3 (b), the shape of the recess 35 of the outer flange 32 may be changed, and the shape shown in FIG.
As shown in (a) and (b), by changing the shape of the limiter pin 36, the torque limit at which the limiter pin 36 is disengaged from the recess 35 of the outer flange 32 can be set. Although not shown in detail, the torque limit at which the limiter pin 36 comes off can be set by changing the strength of the spring 37 that presses the limiter pin 36 toward the recess 35 of the outer flange 32.

Further, as shown in FIG. 5A, when the recess 35 is formed in the outer flange 32, the torque limit in the high speed rotation range of the engine 11 becomes large. On the other hand, FIG.
As shown in (b), when the recess 35 is formed in the inner flange 31, the torque limit in the low speed rotation range of the engine 11 becomes large.

As described above, the balancer driven gear 2
When the excessive torque of the crankshaft 15 is applied to 9, the limiter pin 36 is disengaged from the concave portion 35 of the outer flange 32 and the outer flange 32 idles, so that the balancer drive gear 24 and the balancer driven gear 29 do not generate a rattling noise.

Further, since the limiter device 33 is provided only at one place, the outer flange 32 with the limiter pin 36 disengaged from the concave portion 35 makes one rotation around the outer circumference of the inner flange 31, and then the limiter pin 36 again returns to the original position. Engages with the inner flange 31 and does not change the phase between the balancer weight 28 and the crankshaft 15.

Further, since the crank balancer 25 does not consume the output of the engine 11, the limit of torque transmitted to the crank balancer 25 can be set low by providing the limiter device 33. As a result, at least one of the balancer drive gear 24 and the balancer driven gear 29 can be made of plastic, for example, and the generation of rattling noise can be further reduced.

Furthermore, although the balancer driven gear 29 is provided with the limiter device 33 in the above-mentioned embodiment, the same effect can be obtained by providing the balancer drive gear 24 with the limiter device 33.

By the way, when the limiter device 33 is provided on the gear made of plastic, the strength of the limiter device 33 itself is a concern, but in this case, as shown in FIGS. 6 (a) and 6 (b), The strength can be secured by providing an insert member 38 made of a hard material such as metal on the inner peripheral surface of the flange 32.

The crank balancer 25 may be provided with a conventional spring damper or rubber damper in addition to the limiter device 33 described above.

[0028]

As described above, according to the crank balancer drive system for an engine of the present invention, the balancer driven gear provided on the balancer shaft is interlocked with the balancer drive gear provided on the crankshaft to rotate the engine. In a crank balancer drive device for an engine that eliminates vibration during operation, one of the balancer drive gear and the balancer driven gear is provided on an inner flange fixed to the shaft, and rotatable relative to the inner flange. The donut-shaped outer flange is divided into two parts, and a limiter device is provided at one place on the sliding contact surfaces of these flanges.
When the engine rotates stably, the both flanges are integrally rotated, and the rotation of the crankshaft is transmitted to the balancer shaft.On the other hand, when excessive torque is applied to the outer flange, the rotation of the crankshaft is transferred to the balancer shaft. Since it is configured to be in a non-transmission state,
When an excessive torque of the crankshaft is applied to the gear, the outer flange idles, the cost is not required, and the rattling noise between the gears can be reduced with a simple structure.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of an engine showing an embodiment of a crank balancer driving device for an engine according to the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

3A and 3B are views showing variations of the shape of the concave portion of the outer flange.

4A and 4B are views showing variations of the shape of the limiter pin.

5 (a) and 5 (b) are views showing variations of the arrangement position of the limiter device.

6A and 6B are views showing a state in which an insert member is provided on an inner peripheral surface of an outer flange.

FIG. 7 is a diagram showing a conventional crank balancer driving device.

[Explanation of symbols]

 11 engine 12 crankcase 15 crankshaft 24 balancer drive gear 25 crank balancer 26 balancer shaft 28 balancer weight 29 balancer driven gear 30 crank balancer drive device 31 inner flange 32 outer flange 33 limiter device 34 inner flange pin storage portion 35 outer flange recess 36 Limiter pin 37 Spring

Claims (1)

[Claims] 1. A crank balancer driving device for an engine, wherein a balancer driven gear provided on a balancer shaft is interlocked with a balancer drive gear provided on a crankshaft to remove vibration during engine operation. One of the balancer driven gears is divided into an inner flange fixed to the shaft and a donut-shaped outer flange rotatably provided on the inner flange, and the sliding contact surfaces of these two flanges are divided. In addition to providing a limiter device at one place, this limiter device integrally rotates both flanges during stable rotation of the engine, while transmitting the rotation of the crankshaft to the balancer shaft, while excessive torque is applied to the outer flange. If it is applied, the crankshaft rotation A crank balancer drive device for an engine, characterized in that it is configured to be in a non-transmitting state to a balancer shaft.