GB2303899A

GB2303899A - Clutch disc assembly with wedges between torsion damping springs

Info

Publication number: GB2303899A
Application number: GB9615514A
Authority: GB
Inventors: Helmuth Weissenberger; Reinhold Weidinger
Original assignee: Fichtel and Sachs AG
Current assignee: ZF Sachs AG
Priority date: 1995-08-02
Filing date: 1996-07-24
Publication date: 1997-03-05
Anticipated expiration: 2016-07-24
Also published as: ES2147057A1; GB9615514D0; FR2737546B1; GB2303899B; FR2737546A1; DE19528319C1; ES2147057B1

Description

1 2303899 CLUTCH DISC ASSEMBLY WITH WEDGES BETWEEN TORSION DAMPLNIG

SPRINGS The invention relates to a clutch disc assembly.

A known clutch disc assembly disclosed in W092/00470 employs a hub fitted onto a transmission shaft for rotation therewith which carries a pair of cover plates which are secured together and serve as torque output elements. A carrier plate supporting ffiction linings which serves as a torque input element extends between the cover plates. Helical springs are coupled between the cover plates and the carrier plate and are compressed under loading and relative rotation between the cover plates and the carrier plate to dampen torsional vibration. In this construction there are two axially adjacent sets of springs and the individual sets of springs are loaded by separate drive elements. Apart from the many individual parts required to drive the springs there are in addition problems with increasing frictional forces at higher speeds.

An objective of the present invention is to create an improve assembly which avoids the disadvantages of the prior art.

According to the invention there is provided a clutch disc assembly for a friction clutch; said assembly comprising a hub for fitting onto a transmission shaft for rotation therewith which defines an axis of rotation, cover plates which are secured to the hub and axially spaced apart to function as torque output elements, a torque input element between the cover plates which is provided with friction linings and at least two sets of helical springs between the input element and the output elements which are compressed under the torque loading and relative rotation of the output elements and input element, the springs being arranged axially adjacent to one another in pairs with the springs of each set being loaded simultaneously by drive elements, characterised in that the sets of springs are connected in series with the springs of each set being separated by axial wedges each one of which loads two adjacent helical springs and at least one rotatably mounted support disc is disposed axially between the cover plates which is penetrated by the wedges in corresponding openings and radially outer edges of the openings serve to support and guide the wedges.

With the arrangement of the two sets of helical springs in series and axially arranged wedges which load the two adjacent helical springs and the provision of the support disc which secures the wedges radially outwards it is possible to keep friction in the system at a very low level even at high speeds.

The support disc can be centred on the hub in particular on a web of the hub resulting in correct guiding about the axis of rotation.

The cover plates serving as the output elements may have annular regions extending perpendicular to the axis of rotation and secured, as by rivets, on the web of the hub. Although rivets are preferred other securing means are possible e.g. welding. At a radial distance from the web the cover plates are curved in opposite directions away from one another like a pot. Radial outer walls adjoin the curved regions or sections of the cover plates. The helical springs of each set are then arranged between the radial wall and the curved section of one cover plate on one side and the support disc on the other. In this way the springs can be guided accurately by both cover plates radially inwards and in the axial direction without producing undesired ffiction.

3 A friction lining carrier plate serving as the input element is concentric to the axis of rotation and is optionally assembled to further cover lates resulting in a symmetrical P 0 input element with a U-shaped or T-shaped cross section with walls extending parallel to and a short distance from the inner surface of the radial walls of the cover plates remote from the hub. The input element can thus be guided in an vial direction by the radial walls of the cover plates and closes off the space occupied by the helical springs radially outwards.

According to a fimher feature of the invention axial tabs project out from the input element conveniently from curved regions of the further cover plates merging axial and radial wall regions. These tabs form a centring alignment relative to the outer edges or rims of the radial walls of the cover plates. By means of this simple construction without additional individual parts radial guidance between the input element and the output elements is ensured.

The ends of the helical springs opposite the associated wedge are preferably supported by two spacing parts extending parallel to the axis of rotation which he closely on top of one another in the radial sense. The planer interface between the spacing parts extends approximately through the centres of the end faces of the helical springs. The radially outermost spacing part is secured to the input element as, for example, to the further cover plates and the radially inner most spacing part is secured to the radial walls of the cover plates acting as the output elements. The spacing parts thus extend axially over the entire extent of the end faces of the helical springs and always control simultaneously the axially adjacent helical springs. A preferred securing means is for the 4 radially outermost spacing part to be welded to the further cover plates of the input element and for the radially innermost spacing part to be locked in the radially walls of the cover plates. The welding of the outer spacing part saves space particularly in axial direction, and no substantial projections are created. The other inner spacing part can penetrate openings in the cover plates with narrower projections and are additionally riveted or welded from the outside.

The support disc can also have corresponding openings in the region of the spacing parts by means of which the peripheral freedom of movement of the spacing parts is ensured.

According to a further feature of the invention a friction device is provided axially between the annular regions of the cover plates and the support disc and radially between the web of the hub and the helical springs which permits friction clamping between the cover plates and the support disc. In this way the friction device is activated by the support disc according to a specific angle of rotation of the clutch disc assembly and only when the prestressing force of the wedge of the loading helical springs exceeds the force of the friction device.

The friction device preferably comprises at least one axial forceproducing spring which is supported on one of the cover plates and loads the support disc in the direction of the other cover plate for frictional clamping. To obtain precisely maintained frictional forces friction rings with a defined frictional value can be inserted between the individual parts.

It is also possible to connect more than two different sets of helical springs in series. If three sets of helical springs are used then two sets of wedges are necessary. In such a design a first support disc can be provided for the first set of wedges and the second set of wedges interacts with two further supports discs which are arranged symmetrically on both sides of the first support disc. In this way without using a large amount of axial space it is possible to alleviate the centrifugal force from each set of wedges independently.

Embodiments of the invention will now be explained in more detail in the following description and the accompanying drawings wherein:

Figure I is a part-sectional end view of part of a clutch disc assembly constructed in accordance with the invention; Figure 2 is a sectional view of the clutch disc assembly represented in Figure 1, the view being taken along the line B-B of Figure 1; Figure 3 is a sectional view of the clutch disc assembly represented in Figure 1, the view being taken along the fines C-C of Figure 1; Figure 4 is a part-section representation depicting part of a modified form of a clutch disc assembly constructed in accordance with the invention, and Figure 5 depicts an arrangement of several support discs in the embodiment relating to Figure 4.

A clutch disc assembly according to Figures I to 3 comprises a hub 2 which is rotationally locked on a transmission shaft (not shown) and extends concentrically relative to an axis of rotation 3. The hub 2 has a radially outwardly projecting web 19 6 onto which two cover plates 4 and 5 are secured by rivets 2 1. The component parts 2,4,5 can be considered as the output of the clutch disc assembly 1. The two cover plates 4 and 5 rest with their annular regions 20 on the side of the web 19 of the hub 2 and have curved sections 23 at a radial distance form the web 19 which are directed away from one another. The curved sections 23 give the cover plates 4 and 5 a pot-like shape. The curved sections 23 adjoin radial walls 22. Sets of helical springs 6 and 7 are arranged in the cavity defined between the curved sections 23, Two further cover plates 25 and 26 are firmly secured to a lining carrier 24. The lining carrier 24 runs radially outwards and carries the fiction linings 18. The two further cover plates 25 and 26 are almost L-shaped each with one wall which runs parallel to the axis of rotation and at a distance from the lining carrier 24 turns into a radially inwardly projecting wall 27. The two walls 27 are close to the inner surfaces of the walls 22 of the cover plates 3 and 4. The further cover plates 25,26 and the carrier 24 can be considered as the input of the clutch disc assembly.

As shown in particular in Figures 2 and 3 a pair of two identical helical springs 6,7 each belonging to a set of springs arranged in circumferential series are arranged adjacent to one another axially, They are driven, as shown in particular in Figure 3 by spacing parts 16, 17 which extend parallel to the axis of rotation 3 and lie closely on top of one another radially. The interface between the spacing parts 16,17 runs through the centres of the end faces of the helical springs 6,7. The radially outer spacing part 16 is anchored securely to the walls 27 of the cover plates or input elements 25,26 and the radial inner spacing part 17 is anchored firmly on the walls 22 of the cover plates or output elements 7 4, 5. The spacing parts 16 and 17 can be secured in diffierent ways. In the present case the connection is designed so that the spacing parts 16, 17 extend into corresponding openings of the input or output elements 25, 26,45 with projections. The spacing parts 16 are welded to the elements 25,26 and the spacing parts 17 are additionally secured by riveting. The riveting of spacing parts 16 would also be possible, but such a connection must not result in undue enlargement of the width of the walls 27 in both axial directions as otherwise thus would produce uncontrollable friction with the inner surface of the walls 22.

As shown in particular in Fig. 1 there are two sets of helical springs 6, 7 are provided which are connected in series. Wedges 9 are arranged between the end faces of the adjacent helical springs 6 or 7 which are at opposite ends to the spacing parts 16 and 17. The wedges 9 transfer the force loading from one helical spring to the next. The springs 6,7 are free floating in a peripheral direction and are supported in the radial direction to alleviate the centrifugal force. The support is provided by a support disc 11 which according to Figs 1 and 3 extends between the pairs of helical springs 6, 7 in the radial direction. It is shown in Fig. 3 that the spacing parts 16,17 penetrate the support disc 11 in correspondingly large openings 15. The support disc 11 is guided circum&renfially on the outer surface of the web 19 of the hub 2 and has openings 13 which are penetrated by the wedges 9 whereby each wedge 9 can be supported radially on an edge 14 of the associated opening 13. By means of the arrangement of the support disc 11 axially between the sets of springs 6,7 the wedges 9 are supported in the region 8 of the centre of gravity and without a risk of tilting. The wedges 9 have curved recess 32 which mate with the inner diameters of the springs 6,7 As shown in Figures. 2 and 3 the support disc 11 in its radially inner region, ie. wdally between the annular regions 20 of the cover plates 4 and 5 is held by a fliction device. This friction device comprises at least one spring 29 which is supported on one annular region 20 and produces a clamping force between the support disc 11 and the annular regions 20. In the present case a pressing ring 30 is also provided which is rotationally-locked with the annular region 20 and is mounted to be axially displaceable. Such an arrangement is known from conventional clutch disc assemblies. Furthermore, several friction rings 31 are stacked together with the disc 11 directly between the pressing ring 30 and the other opposite annular region 20 to ensure a precisely defined friction force. Axial guidance between the input elements 25,26 and the output elements 4,5 is provided by the walls 27 of the elements 25 and 26 and the inner surface of the walls 22 of the elements 4 and 5 and radial guidance is achieved by axial tongues or tabs 28 of the elements 25 and 26 running parallel to the axis of rotation 3 which extend axially outwardly of the walls 27. These tabs 28 overlie the radially outer rims or edge surfaces of the walls 22.

The operation of the clutch disc assembly 1 according to Figures 1 to 3 is as follows:

With the torque loading of the clutch disc assembly 1 via the ffiction linings 18 and a secured hub 2 the torque is transferred to the spacing parts 16 via the two cover plates 25 and 26 firrnly connected to the lining carrier 24. The spacing parts 16 direct the 9 torque further to the helical springs 6 or 7 depending on the direction of rotation. Assuming the torque is anticlockwise in Fig. I first the helical springs 7 are loaded which transfers the torque via the wedges 9 to the helical springs 6 and the latter via the spacing parts 17 to the output elements 4, 5 and the hub 2. Together with the relative movement of the wedges 9 the support disc I I also rotates relative to the output elements 4, 5, whereby the fiiction device comprising parts 29, 30, 31 can be activated. The ftictional force of the fiiction device is overcome only when the prestressing of the helical springs 7 exceeds a predetermined value. The friction device is effective in connection with the support disc I I in both directions of rotation. The wedges 9 are supported radiafly in the openings 13 of the support disc I I and the curved recesses 32 in the wedges 9 support the springs 6,7 in a radial direction against centrifugal force.

A variant is shown in Fig. 4 and 5 in which altogether three sets of helical springs 6, 7, 8 are driven in series. For this modified design the two wedges 9 and 10 are provided for each set of helical springs 6-8. Both wedges 9 and 10 are identical in design and their function corresponds to the description of Figs. I to 3. The drive of each set of helical springs 6 to 8 is performed in the manner described by the spacing parts 16 and 17. The already described support disc 11 is provided for the centrifugal force support of the first set of wedges 9 which is arranged centraUy in the output elements 4, 5. To support the wedges 10 two additional support discs 12 are provided which are arranged symmetricafly to the support disc I I with one support disc 12 on either side of the support disc 11. The support discs 12 have openings 33 in the region of the openings 13 of support disc I I which are larger in size and only serve for the passage of an associated wedge 9 which is supported on the support disc 11 by the edge 14 and can move freely in the openings 33 of the support discs 12. The wedges 10 are supported radially in corresponding openings 13 whereby in these regions the support disc I I also has larger windows for the entry of the wedges 10. The operation of this modified design is otherwise similar to the operation of the assembly I according to Figs. I to 3. The input of force is performed via one of the end helical springs 6,8 and is conveyed by a first wedge 9, the middle helical springs 7, a second wedge 10 and the other end spring 8,6. Also in this arrangement the support discs 11, 12 are provided with a fitiction device for damping torsion vibrations.

11

Claims

Claims

1. A clutch disc assembly for a friction clutch; said assembly comprising a hub for fitting onto a transmission shaft for rotation therewith which defines an axis of rotation, cover plates which are secured to the hub and axially spaced part to function as torque output elements, a torque input element between the cover plates which is provided with friction linings and at least two sets of helical springs interposed between the input element and the output elements which are compressed under the torque loading and relative rotation of the output elements and input element, the springs being arranged axially adjacent to one another in pairs with the springs of each set being loaded simultaneously by drive elements; characterised in that the sets of springs are connected in series with the springs (6-8) of each set being separated by axial wedges (9, 10) each one of which loads two adjacent helical springs and at least one rotatably mounted support disc (11, 12) is disposed axially between the cover plates (4,5) and the disc (11, 12) is penetrated by the wedges (9, 10) in corresponding openings (13) and radially outer edges (14) of the openings (13) serve to support and guide the wedges (9, 10).

2. A clutch disc assembly according to claim 1, wherein the support disc (11, 12) is centred on the hub (2).

3. A clutch disc assembly according to claim 1 or 2, wherein the cover plates (4,5) have annular regions (20) extending perpendicular to the axis of rotation (3) engaging on a peripheral web (19) of the hub (2) curved sections extending away from one another like a pot at a radial distance from the web (19) and outer radial walls (22) adjoining the curved sections (23) the sets helical springs (6-8) each being arranged between the radial 12 walls (22) and the curved section (23) of one of the cover plates on one side and the support disc (11) on the other.

4. A clutch disc assembly according to claim 3, wherein the input element is symmetrically concentric to the axis of rotation.

5. A clutch disc assembly according to claim 4, wherein the input element is composed of a carrier plate (24) supporting the ffiction linings (18) and two further cover plates (25,26) which combine to form an input element with a T or U-shaped cross-section.

6. A clutch disc assembly according to claim 5, wherein axial -tabs (28) project from the walls of the further cover plates (25,26) and form a centring alignment relative to the outer rims or edges of the radial walls (22) of the cover plates (4,5).

7. A clutch disc assembly according to claim 6, wherein the ends of the helical springs (6,S) opposite the wedges (9-11) are supported by spacing parts (16,17) acting as the drive elements, the spacing parts extending parallel to the axis of rotation (3) which lie closely adjacent radially, the planer interface between the spacing parts (16,17) being aligned with the centres of the end faces of the helical springs (6-8), the radially outermost spacing part (16) being secured to the walls (27) of the further cover plate (25,26) and the radially inner most spacing part (17) being secured to the radial walls (22) of the cover plates (4,5).

8. A clutch disc assembly according to claim 7, wherein the support disc (11) has openings (15) for accommodating the spacing parts (16,17).

13 9. A clutch disc assembly according to claim 7 or 8, wherein the outer spacing part is preferably welded to the walls (27) of the further cover plates (25,26) and the spacing part ( 17) is locked in the radial walls (22) of the cover plates (4, 5).

10. A clutch disc assembly according to any one of claims 3 to 9, and further comprising a ffiction device disposed axially between the annular regions (20) of the cover plates (4,5) and the support disc (11) and radially between the web (19) and the hub (2) and the helical springs (68) for friction clamping between the cover plates (4,5) and the support disc (11).

11. A clutch disc assembly according to claim 10, wherein the friction device includes at last one axial force-producing spring (29).

12. A clutch assembly disc according to any one of claims 3 to 11, wherein there are three sets of helical springs (6-8) arranged in pairs, the sets being arranged in series, a first support disc (11) is provided for the arrangement of first wedges (9) between the first and second set of springs (6,7) and two further supports discs (12) are provided on both sides of the first support disc (11) for the arrangement of second wedges (10) between the second and third set of springs (7,8).

13. A clutch disc assembly substantially as described with reference to, and as illustrated in, Figures 1 to 3 or Figures 1 to 3 as modified by Figures 4 and 5 of the accompanying drawings.