1. Field of the Invention
The present invention pertains to a clutch disk, comprising a hub area and a plurality of friction lining elements carried by the hub area, following each other in the circumferential direction with respect to the rotational axis of the clutch disk, these elements providing at least part of the friction surface area, where the friction lining elements are designed to make frictional contact with the associated opposing friction surface of a flywheel, a pressure plate, or the like.
2. Description of the Related Art
In the clutch disks according to the state of the art, the friction linings are usually attached to a hub area, e.g., by way of a system of lining springs, in such a way that they can shift in the axial direction, as by way of the spring system, as the clutch is being engaged and disengaged. Other degrees of freedom for the movement of the friction linings are usually not available. This type of rigid connection of the friction linings to the hub area of a clutch disk, however, causes the problem that, as a result of local changes in, for example, the coefficient of friction or in the normal force prevailing between the friction linings and an opposing friction surface, frictional vibrations can be excited, which can lead to low-frequency noise, especially when relatively large masses are vibrating in phase with each other, to high-frequency noise (squeal), and even to the so-called xe2x80x9cgrabbingxe2x80x9d of the clutch.
It is the object of the present invention to improve a clutch disk of the general type in question in such a way that side effects produced by the frictional vibrations which occur during slipping of the clutch can be avoided as completely as possible.
This object is accomplished according to the invention by a clutch disk comprising a hub area and a plurality of friction lining elements supported on the hub area, which are arranged in sequence around the circumference relative to the rotational axis of the clutch disk, and which provide at least part of the friction surface area, where the friction lining elements are designed to make frictional contact with the associated opposing friction surface of a flywheel, a pressure plate, or the like.
It is also provided that at least one friction lining element is supported on the hub area in such a way that it can shift position in the circumferential direction relative to the rotational axis.
In the clutch disk according to the invention, therefore, the friction lining elements or at least one of the friction lining elements can move with an additional degree of freedom, namely, that of motion in the circumferential direction. It is therefore possible for the friction lining element to shift position slightly with respect to the hub area in response to local changes in the friction conditions between a friction lining element of this type and the opposing friction surface cooperating with it; that is, an otherwise spontaneously occurring shock is absorbed, and the danger that vibrations would be induced by such a shock is therefore almost completely eliminated.
As already indicated, it can be provided that the minimum of one friction lining element is designed so that it can shift position in the circumferential direction at least in response to a change in the sliding frictional interaction between its friction lining surface and the opposing friction surface which is or can be assigned to the element.
In order to ensure that at least one friction lining element can execute a defined movement relative to the hub area especially under the action of centrifugal force, it is also possible to provide according to the invention an additional guide device for circumferential movement, by means of which the minimum of one friction lining element is guided in the circumferential direction with respect to the hub area.
A design which is especially reliable in operation and simple to construct can be obtained by using a telescoping guide device as the circumferential movement guide device. As an alternative, it is possible for the circumferential movement guide device, which is in either the minimum of one friction lining element or in the hub area, to comprise at least one guide recess, into which a corresponding guide projection of the other assembly, i.e., of either the hub area or of the friction lining element, can movably engage in the circumferential direction. It is also possible for the circumferential movement guide device to comprise at least one guide area or part on which a radially outward side of the minimum of one friction lining element or a support element carrying it can be supported.
In an alternative design of the clutch disk according to the invention, the possibility of allowing at least one friction lining element to shift in the circumferential direction relative to the rotational axis can be obtained by allowing the minimum of one friction lining element to swivel relative to the hub area around a swivel axis which is essentially parallel to the rotational axis and a certain distance away from it in the radial direction.
To ensure that, after a brief change in the frictional relationships, the previous set of kinematic and positional relationships are restored, it is also preferable to provide a restoring device for exerting pretension on the minimum of one friction lining element, which acts to hold it in a home circumferential position relative to the hub area.
This restoring device can comprise, for example, at least one spring element, which can be designed as an integral part of the hub area or of a component attached to the hub. As an alternative, it is possible for the ends of the minimum of one restoring spring element to be supported relative to the hub area and the minimum of one friction lining element.
In another design variant of the clutch disk according to the invention, the restoring function mentioned can be realized by providing the minimum of one friction lining element with at least two friction lining element parts, which are free to move relative to each other and relative to the hub area in the circumferential direction, and by allowing the restoring device to act between the minimum of two friction lining elements parts. In addition, by taking advantage of the dimensional stability properties of elastomeric materials, a restoring force can be obtained very easily by providing the restoring device with at least one area of elastomeric material in an area between the hub area and the minimum of one friction lining element or the friction lining of said element. In addition, it is possible for the restoring device to comprise at least one area of elastomeric material acting between two friction lining parts of the minimum of one friction lining element.
To take into account local changes in the frictional conditions in particular, without thus producing effects on other frictionally cooperating areas, it is proposed that it be possible for the minimum of one friction lining element or for a group of friction lining elements to move in the circumferential direction essentially independently of other friction lining elements or groups of friction lining elements.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, and specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.