CLUTCH DAMPER ASSEMBLY

Abstract

A damper assembly for a clutch, the damper assembly being configured to transfer torque from a driven plate of the clutch to an output shaft of the clutch, a torque transfer plate of the damper assembly including at least one surface coating configured to alter the acoustic properties of the torque transfer plate.

Claims

1. A clutch comprising: a driven plate; an output shaft; and a damper assembly, configured to transfer torque from the driven plate to the output shaft, including a torque transfer plate having an acoustic coating on at least one non-frictional surface of the torque transfer plate.

2. The clutch of claim 1 wherein the acoustic coating is on at least a portion of an axially facing face of the torque transfer plate.

3. The clutch of claim 2 wherein the acoustic coating is polytetrafluoroethylene.

4. The clutch of claim 2 wherein the acoustic coating is on at least a portion of a radially facing surface of the torque transfer plate.

5. The clutch of claim 1 wherein the acoustic coating is on at least a portion of a radially facing surface of the torque transfer plate.

6. The clutch of claim 5 wherein the acoustic coating is polytetrafluoroethylene.

7. The clutch of claim 1 wherein the torque transfer plate includes a central opening having teeth projecting radially inward therefrom, with the acoustic coating on at least a portion of the radially inward facing surfaces of the teeth.

8. The clutch of claim 7 wherein the output shaft extends through the central opening and includes radially outward extending teeth that selectively contact either the radially inward projecting teeth of the central opening or the acoustic coating.

9. The clutch of claim 1 wherein the acoustic coating covers the entire torque transfer plate.

10. The clutch of claim 9 wherein the acoustic coating is polytetrafluoroethylene.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] For a better understanding of the present disclosure, 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:

[0018] FIG. 1 shows a schematic exploded view of particular components of a clutch; and

[0019] FIG. 2 shows a schematic partial front view of the clutch.

DETAILED DESCRIPTION

[0020] FIGS. 1 and 2 show a simplified exploded view of a clutch assembly 100 for a vehicle, the clutch assembly 100 allowing for the selective engagement and disengagement of an output shaft of a motor of the vehicle from a transmission of the vehicle, and/or another component of the drivetrain of the vehicle. The clutch may be any appropriate type of clutch configured for use on a vehicle, such a car, a van, a truck, a motor bike, a marine vessel or an aircraft. In particular, the clutch may be a single-mass flywheel clutch for use on a vehicle having a relatively small internal combustion engine. However, in another arrangement, the clutch may be a duel mass flywheel clutch, such as one used on commercial vehicles and/or vehicles with diesel engines. The engine and transmission may be conventional, if so desired, and so will not be shown herein.

[0021] The clutch assembly 100 may include a driven plate assembly 104 comprising a driven plate 101 and friction member 103, the driven plate assembly being configured to transfer torque from the engine to the clutch when the driven plate assembly is brought into engagement with a flywheel of the engine.

[0022] The clutch assembly 100 may include a damper assembly 102, which has first and second disc members 105, 107, respectively, which are rigidly secured to the driven plate assembly 104 in an assembled configuration. The first and second disc members 105, 107 cooperate to form a housing for a set of damper springs 109, a torque transfer plate 111 and an output shaft (hub member) 113 of the clutch 100. Each of the first and second disc members 105, 107 and the torque transfer plate 111 include a plurality of recesses (cut-outs) 106, that are each configured to receive and hold a respective damper spring of the damper spring set 109. When the damper assembly 102 is assembled to the driven plate assembly 104, the torque is transmitted directly from the driven plate assembly 104 to the first and second disc members 105, 107, through the damper spring set 109 to the torque transfer plate 111 and then the output shaft 113. In this manner, fluctuations in the torque output from the engine are damped by the damper assembly 102, which reduces the torque fluctuation seen by the output shaft 113 of the clutch assembly 100.

[0023] One will note, then, that the torque transfer plate 111 does not transfer the torque through surface friction between adjacent components pressed together axially. Thus, the axially facing surfaces (faces) 130 of the torque transfer plate 111 are non-frictional surfaces (i.e., there is no torque transferred via these faces 130 through frictional contact with an axially facing surface of another component in the clutch assembly 100 pressed against one of these faces 130. Accordingly, no frictional surface material for transferring torque is needed or employed on these faces 130. Additionally, teeth 116 that extend radially inward from a central opening 114 (discussed below), and mate with teeth 118 from the output shaft 113 (discussed below) are non-frictional surfaces in that the torque transfer is not through frictional contact but through normal (directionally speaking) contact between the surfaces.

[0024] FIG. 2, in view of FIG. 1, shows a view of the rotational coupling between the torque transfer plate 111 and the output shaft 113 of the clutch assembly 100. The torque transfer plate 111 includes a central opening 114 that axially receives the output shaft 113. The first and second disc members 105 support the output shaft 113 in the opening 114 of the torque transfer plate 111 such that there is a radial clearance between the outer diameter 120 of the output shaft 113 and the inner diameter 114 of the opening of the torque transfer plate 111. However, in one or more other arrangements, the output shaft 113 may be supported in any appropriate manner by one or more appropriate components of the clutch assembly 100.

[0025] The torque transfer plate 111 is rotationally coupled to the output shaft 113 by virtue of a plurality teeth that mesh with one another. For example, the torque transfer plate 111 may include a plurality of first teeth 116 that extend radially inward from the opening 114 of the torque transfer plate 111, and a plurality of second teeth 118 that extend radially outward from the outer diameter 120 of the output shaft 113. In some clutch arrangements (not shown), the teeth of the torque transfer plate 111 and the output shaft 113 are configured such that there is little backlash (play) between the teeth. However, the clutch shown in FIG. 2 comprises a substantial amount of backlash between the teeth 116 of the torque transfer plate 111 and the teeth 118 of the output shaft 113. The provision of such an amount of backlash enables the rotational interface between the torque transfer plate 111 and the output shaft 113 to function as a pre-damper stage of the clutch assembly 100, which acts to further reduce the transfer of torque fluctuations from the engine to the drivetrain.

[0026] However, with the introduction of increasingly strict efficiency and emissions requirements, it has become desirable to reduce the amount of friction between drivetrain components, which can lead to an increase in undesirable noises and acoustic phenomena, such as rattle. One way in which rattle can be reduced is to increase the amount of damping in the pre-damper stage of a clutch, i.e. by increasing the amount of backlash between the teeth 116 of the torque transfer plate 111 and the teeth 118 of the output shaft 113. However, this can lead to higher levels of impact loading within the pre-damper stage of a clutch assembly 100, e.g. as the teeth engage one another, which can increase the levels of clonk perceived by the user.

[0027] The present disclosure provides a clutch assembly 100 having improved noise vibration and harshness characteristics. In particular, the present disclosure provides the torque transfer plate 111 for the clutch assembly 100, the torque transfer plate 111 having improved acoustic properties, which result in a reduction in the audible noise, e.g. clonk, that can be heard while operating the clutch assembly 100.

[0028] The shape of the torque transfer plate 111 is a thin disc comprising cut-outs for the damper spring set 109. As a result of the inherent shape of the torque transfer plate 111, the torque transfer plate 111 has a natural frequency close to the operational frequencies encountered during its operation, which serves to amplify any impact sound inputs, resulting in undesirable audible sounds, such as clonk.

[0029] In order to alter the acoustic properties, e.g. the natural frequency of the torque transfer plate 111, the torque transfer plate 111 comprises a surface coating 122. For example, the torque transfer plate 111 may comprise a functional surface coating 122 configured to alter the acoustic properties of the torque transfer plate 111. In this manner, the acoustic response from the torque transfer plate 111 under impact sound inputs may be substantially different when compared to an un-coated torque transfer plate 111. Thus, the application of a surface coating 122 to a torque transfer plate 111 leads to a reduced level of undesirable audible sounds.

[0030] The surface coating 122 may be formed from any material having significant acoustic damping properties. In one arrangement, the surface coating 122 may be a polytetrafluoroethylene coating. The surface coating 122 may be applied using any appropriate coating process, such as vapor deposition, chemical and electrochemical techniques, spraying, roll-to-roll coating processes, and/or physical coating processes. Importantly, the surface coating 122 may be applied so as to not affect the design function of the torque transfer plate 111, i.e. its ability to transfer torque between the driven plate assembly and the output shaft of the clutch, e.g. by altering the shape and/or size of the torque transfer plate 111.

[0031] In one arrangement, the surface coating 122 may be applied over the entire outer surface of the torque transfer plate 111, e.g. over the axial end faces 130 and the radial outer 132 and inner 134 surfaces of the torque transfer plate 111. However, in some cases, it may be desirable to mask certain areas of the torque transfer plate 111 to prevent the surface coating 122 being applied to those areas. For example, the material of the torque transfer plate 111, and the output shaft 113, may be selected to optimize the interaction, e.g. contact mechanics, between the teeth 116 of the torque transfer plate 111 and the teeth 118 of the output shaft 113. In such circumstances, it may be desirable to not apply a surface coating 122 to the teeth 116 of the torque transfer plate 111, so as to not alter the interaction between the torque transfer plate 111 and the output shaft 113.

[0032] The present disclosure also provides a method of acoustically tuning a clutch component, such as the above mentioned torque transfer plate 111. For example, the method may comprise a step of determining the acoustic properties of the torque transfer plate 111, for example determining one or more resonant frequencies of the torque transfer plate 111. The method may comprise step of applying a surface coating 122 to the torque transfer plate 111 in order to adjust the determined acoustic properties.

[0033] It will be appreciated by those skilled in the art that although the disclosure has been described by way of example with reference to one or more arrangements, it is not limited to the disclosed arrangements and that alternative arrangements could be constructed without departing from the scope of the disclosure as defined by the appended claims.