The present invention relates to a torque transmitting arrangement which includes means for absorbing or compensating for torsional vibrations such as can arise in a vehicle transmission assembly.

Torque transmitting arrangements are known for example from U.K. Patent Application No. 2 152 187A in which two coaxial flywheel masses are rotatable relative to each other over a limited angle with damping means acting between the two flywheel masses. However the prior art construction is complex and prone to failure and it is desirable to provide a more simple arrangement.

It is an object of the present invention to provide a torque transmitting arrangement which incorporates a damping effect and which is simple in construction and effective in use.

According to the present invention there is provided a torque transmitting arrangement comprising two coaxially mounted flywheel masses which are connected together by a plurality of resilient members which permit limited angular movement of the flywheel masses relative to each other and which act as damping means.

Preferably, one of the flywheel masses is supported on the other of the flywheel masses by means of a journal bearing.

A thrust washer may be provided between the flywheel masses to maintain axial separation of the flywheel masses.

The resilient members may be made of rubber. The resilient members may be bonded to the outer periphery of one of the flywheel masses, or may be bonded to a carrier ring which is secured to one of the flywheel masses. The radially outer surfaces of the resilient members may be bonded to a retaining ring, which retaining ring may be secured to the other of the flywheel masses.

One of the flywheel masses may be provided with a face for receiving a friction disc of a friction clutch.

For a better understanding of the present invention and to show more clearly how it may be carried into effect reference will now be made, by way of example, to the accompanying drawings in which:

Figure 1 is a cross-sectional view of part of a vehicle transmission assembly incorporating one embodiment of a torque transmitting arrangement according to the present invention;

Figure 2 is a cross-sectional view taken along the line II-II in Figure 1;

Figure 3 is a cross-sectional view of part of a vehicle transmission assembly incorporating another embodiment of a torque transmitting arrangement according to the present invention; and

Figure 4 is a cross-sectional view taken along the line IV-IV in Figure 3.

Figures 1 and 2 show a flywheel which is divided into two flywheel masses 1 and 2. The flywheel mass 1 is fastened on a crankshaft (not shown) of an internal combustion engine (not shown) by way of bolts 3 and a friction clutch 4 is secured to the flywheel mass 2. The friction clutch 4 comprises a pressure plate 5 for urging a clutch disc 6, which is carried on an input shaft of a gear box (not shown), against the flywheel mass 2. The pressure plate 5 of the friction clutch 4 is urged against the flywheel mass 2 by a diaphragm spring 7 which is pivotally mounted on a clutch cover 8. The clutch cover 8 is secured to the flywheel mass 2. By actuation of the friction clutch 4, the flywheel mass 2 and thus also the flywheel mass 1 can be coupled to and uncoupled from the input shaft of the gearbox by way of the clutch disc 6.

The flywheel mass 1 comprises an annular plate which is secured in its radially inner region to the crankshaft by means of the bolts 3. A starter ring 9 is mounted around the periphery of flywheel mass 1. The flywheel mass 2 comprises an annular plate which is supported on an annular projection 10 formed on the flywheel mass 1 and is separated radially therefrom by a journal bearing 11. A thrust washer 12 is provided to maintain axial separation between the flywheel masses 1 and 2.

Bonded to the periphery of the flywheel mass 2 is a plurality (three as shown in the drawings) of resilient members or inserts 13, for example of rubber. The radially outer surfaces of the resilient inserts 13 are bonded to a retaining ring 14 which is secured to the flywheel mass 1 by means of screws 15.

The thrust washer 12 and journal bearing 11 permit the two flywheel masses 1 and 2 to rotate relative to each other.

However, relative rotation is controlled by the resilient inserts 13.

In operation, under no-load conditions with the clutch disengaged, there are no relative rotational forces of any significance between the flywheel masses 1 and 2 and the resilient inserts are substantially unstressed. Any small

forces are absorbed due to the resilient nature of the inserts 13. When the clutch is engaged and power is transmitted from flywheel mass 1 to flywheel mass 2 the relative rotational forces create a tendency for the two masses to rotate relative to each other. The resilient inserts become increasingly stresssed as relative rotation increases and eventually prevent further relative rotation, but at the same time the resilient nature of the inserts enables them to absorb small fluctuations in load. The effects are similar under conditions of over-run.

The torque transmitting arrangement shown in Figures 3 and 4 is similar to that shown in Figures 1 and 2 and the same reference numerals are used to denote the corresponding parts. The embodiment shown in Figures 3 and 4 will not be described in detail due to the similarity with the embodiment described above with reference to Figures 1 and 2. The difference between the two embodiments is that according to Figures 3 and 4 the resilient members or inserts 13 are not bonded directly to the periphery of the flywheel mass 2 but are bonded to a carrier ring 20 which is secured to the flywheel mass 2 by means of mounting bolts (not shown) for the clutch cover 8 which are received in threaded holes 21 in the flywheel mass 2. The operation of the embodiment shown in Figures 3 and 4 is identical to the operation of the embodiment shown in Figures 1 and 2.

The torque transmitting arrangement of the present invention provides a particularly simple and cost-effective torque transmitting arrangement.