JPS6348841Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a crankshaft device in which an inertia ring is freely attachable and detachable to the crankshaft system of an internal combustion engine to suppress torsional vibration and rotational fluctuation of the crankshaft.

In an automobile engine, in order to reduce rotational fluctuations caused by engine torque fluctuations in the low rotational speed range such as when idling, and to suppress vibrations and maintain smooth rotation, a A flywheel 2 is attached to the end. The larger the mass of the flywheel 2, the more effective it is in reducing engine rotational fluctuations, but if the inertial mass of the flywheel 2 is increased, the flywheel will be driven more effectively in the high engine speed range where there is less rotational fluctuation. The problem is that a large amount of power is spent on this, leading to deterioration in acceleration response and fuel efficiency.

In order to eliminate such problems, for example, the second
A variable inertia flywheel as shown in Fig. 3 has been proposed (Utility Application No. 109615/1983).

In the figure, reference numeral 3 denotes an inertia ring having a predetermined mass, which is rotatably installed around the crankshaft 1 via a bearing 4, and a plurality of centrifugal clutches 5 are arranged around the outer periphery of the inertia ring 3. will be established.

The centrifugal clutch 5 consists of a brake shoe 9 that rotates in synchronization with the flywheel 2 and a spring 10 that biases the brake shoe 9 inward and presses it against the inertia ring 3. When the brake lever 9 is released, the spring 10 is compressed by the action of centrifugal force, the brake shoe 9 is opened outward, and the inertia ring 3 is released from the crankshaft 1, leaving it in a free state.

By doing this, it is possible to improve the acceleration response in the high speed range, and to suppress rotational fluctuations that are particularly significant in the low speed range.

However, in the case of such a variable inertia flywheel, although it is possible to suppress rotational fluctuations in the low speed range, no countermeasures are taken against torsional vibration of the crankshaft 1. When the torsional vibration matches the natural frequency of the crankshaft 1 at the normal rotation speed of the crankshaft 1, the torsional amplitude increases and the vibration becomes intense.

In particular, in this case, the torsional angle amplitude of the crankshaft 1 is maximum at a position opposite to the flywheel 2 with respect to the engine body, that is, at the front side of the engine where the crank pulley 8 and the like are installed.

The present invention aims to solve these problems.

To this end, the present invention includes a crank pulley that is attached to the crankshaft on the opposite side of the engine body from the flywheel, an inertia ring that is rotatably installed on the shaft of the crank pulley via a bearing, and Centrifugal clutch means is provided outside the inertia ring to connect the inertia ring to the crank pulley in a low rotation range of the crankshaft, and to disconnect the inertia ring and the crank pulley in a high rotation range of the crankshaft. The rotational inertia mass of the end of the crankshaft on the crank pulley side, where the torsional angle amplitude is large, is increased in the low speed range.

Embodiments of the present invention will be described below based on the drawings.

As shown in FIGS. 4 and 5, a rotatable disk-shaped inertia ring 12 is installed on the outer periphery of the shaft portion 8A of the crank pulley 8 via a bearing 11.

A plurality of brake shoes 13 are attached to the annular portion 8B of the crank pulley 8 via springs 14, and the brake shoes 13 are located inside the annular portion 8B and press the outer periphery of the inertia ring 12.

In this way, the centrifugal force of the brake shoe 13 caused by the rotation of the crank pulley 8 is applied to the spring 1.
4 constitutes a centrifugal clutch means 15 that connects the inertia ring 12 and the crank pulley 8 with the brake shoe 13 when the force is smaller than the force that urges the brake shoe 13 inward.

In this case, the brake shoe 13 is
2, the moment of inertia of the crankshaft 1 increases by the mass of the inertia ring 12. vice versa,
When the centrifugal action is strengthened, the brake shoe 13 separates from the inertia ring 12 and leaves the inertia ring 12 free to rotate from the crankshaft 1 via the bearing 11, so the moment of inertia of the crankshaft 1 becomes smaller.

Next, the effect will be explained.

In the low engine speed range, the inertia ring 12
The brake shoe 13 is activated by the biasing force of the spring 14.
As a result, the inertia ring 12 rotates integrally with the crank pulley 8.

Therefore, since the inertial mass of the crankshaft 1 on the front side of the engine is increased by the mass of the inertia ring 12, resonance of torsional vibration of the crankshaft 1 that tends to occur in this low speed rotation range can be avoided, and at the same time, the engine It is also possible to suppress rotational fluctuations on the front side.

When the engine speed enters a high speed range, the centrifugal action of the inertia ring 12 increases, and the brake shoe 1
3 is an inertia ring 1 which overcomes the biasing force of a spring 14.
2, the inertia ring 12 is free to rotate outside the bearing 11.

Generally, as the speed range changes from a low speed range to a high speed range, the torsional vibration of the crankshaft 1 approaches the natural frequency that causes resonance. However, since the inertia ring 12 is released from the crankshaft 1, The vibration mode of the shaft 1 changes and moves far away from the resonance point of torsional vibration.

Therefore, it is possible to reduce the torsional amplitude and torsional vibration even in the high-speed range, and also to avoid deterioration of acceleration response, reducing the stress burden on the crankshaft 1 over the entire engine rotation range, and thus reducing the engine speed. fuel efficiency can be increased.

As explained above, according to the present invention, the moment of inertia of the crankshaft is made variable so that it deviates from the torsional natural frequency in each rotation range according to the rotation speed of the crankshaft, so This has the effect of suppressing torsional vibration, preventing rotational fluctuations in the low speed range, and avoiding breakage of the crankshaft.

[Brief explanation of drawings]

Figure 1 is a sectional view showing the main parts of the engine, Figure 2 is a sectional view of a conventional variable inertia flywheel,
3 is a cross-sectional view taken along the line A-A in FIG. 2, FIG. 4 is a cross-sectional view showing an embodiment of the present invention, and FIG. 5 is a cross-sectional view taken along the line A-A in FIG. 4. 1...Crankshaft, 2...Flywheel, 8
... Crank pulley, 8A ... Shaft part, 8B ... Annular part, 11 ... Bearing, 12 ... Inertia ring, 13 ... Brake shoe, 14 ... Spring, 1
5...Centrifugal clutch means.

Claims (1)

[Scope of utility model registration request] A crank pulley is attached to the crankshaft on the opposite side of the engine body from the flywheel, an inertia ring is rotatably installed on the shaft of the crank pulley via a bearing, and the inertia ring is located outside the inertia ring. A crankshaft comprising centrifugal clutch means that connects an inertia ring to the crank pulley in a low rotation range of the crankshaft, and disconnects the inertia ring and the crank pulley in a high rotation range of the crankshaft. Device.