GB2220464A

GB2220464A - Lock-up clutch

Info

Publication number: GB2220464A
Application number: GB8816090A
Authority: GB
Inventors: David Parsons
Original assignee: Automotive Products PLC
Current assignee: Automotive Products PLC
Priority date: 1988-07-06
Filing date: 1988-07-06
Publication date: 1990-01-10
Also published as: GB8816090D0

Abstract

A torque transmitting arrangement, for example an hydraulic torque converter of a vehicle transmission assembly, incorporates a direct coupling or lock-up clutch and comprises a fluid coupling (1) including torque input means to an impeller (2) and torque output means from a turbine (7). The lock-up clutch (17) comprises a clutch friction plate (19) including a friction member (20) which is engageable directly or indirectly with one of the torque input means and the torque output means. The clutch further comprises a first linking element such as a triangular weight (23) pivotally connected to the other of the torque input means and the torque output means by a stub (22), and a second linking element (25) pivotally connected to the clutch friction plate (19) by a stub (26) and to the first linking element (23). For a modification, the clutch directly engages the housing (3) and the stub (26) is mounted on the turbine (7). The linking elements and weights are stated to provide damping by two means. <IMAGE>

Description

TORQUE TRANSMITTING ARRANGEMENT The present invention relates to a torque transmitting arrangement incorporating a direct coupling clutch and more particularly, but not exclusively, relates to a fluid coupling such as an hydraulic torque converter of a vehicle transmission assembly which includes a direct coupling clutch.

Direct coupling clutches are known, for example from United States Patent No. 4,693,348 in which a direct coupling clutch includes a piston slidably mounted on a turbine hub in an axial direction for engaging with and disengaging from a front cover of a fluid coupling and a unitary assembled damper device provided between the turbine hub and the piston. The damper device includes a driven plate consisting of two annular guide plates positioned concentrically with each other, an annular drive plate interposed between the guide plates and being slidable with respect to the guide plates in the circumferential direction and two sets of coil springs arranged in double rows along two concentric circles between the guide plates and being compressed by relative rotation of the drive and driven plates.While this known direct coupling clutch includes a damping device the damping effect operates in stages depending on the intensity of torsional vibration and is not progressive and is not variable with the rotational speed of the vehicle engine.

It is an object of the present invention to provide a torque transmitting arrangement incorporating a direct coupling clutch, which clutch incorporates means for absorbing or compensating for torsional fluctuations which is variable in its effect depending on the rotational speed of the engine.

According to the present invention there is provided a torque transmitting arrangement incorporating a direct coupling clutch, which arrangement comprises a fluid coupling including 'torque input means to an impeller and torque output means from a turbine, and a direct coupling clutch comprising a clutch friction plate including a friction member which is engageable directly or indirectly with one of the torque input means and the torque output means, a first linking element pivotally connected to the other of the torque input means and the torque output means, and a second linking element pivotally connected to the clutch friction plate and to the first linking element.

In one embodiment of the invention, the friction member is engageable with a clutch receiving plate secured to the turbine. The first linking means is preferably pivotally connected to a housing which is rotatable with the impeller. The first linking means may have a greater mass than the second linking means. The pivotal mounting of the first linking means may be located radially inwardly of the pivotal mounting of the second linking means.

In another embodiment of the invention, the friction member is engageable with a housing which is rotatable with the impeller. The first linking means may be pivotally connected to the turbine. The second linking means may have a greater mass than the first linking means. The pivotal mounting of the second linking means is located radially inwardly of the pivotal mounting of the first linking means.

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 diagrammatic cross-sectional view of part of one embodiment of a torque transmitting arrangement including a direct coupling clutch according to the present invention; Figure 2 is a diagrammatic transverse cross-sectional view taken along the line II-II shown in Figure 1; and Figure 3 is a diagrammatic cross-sectional view of part of a second embodiment of a torque transmitting arrangement including a direct coupling clutch according to the present invention.

The torque transmitting arrangement shown in Figures 1 and 2 includes a fluid coupling 1 comprising impeller vanes 2 secured to a rotatable housing 3, stator vanes 4 which are linked to a stationary member 5 by way of a sprag clutch 6 which allows the stator vanes 4 to free wheel during conditions of over-run, that is when the road wheels of a vehicle incorporating the torque transmitting arrangement would otherwise be driving the engine, and a turbine or driven vanes 7 which transmit torque to torque output means in the form of an output shaft 8 by way of a splined drive 9.

The rotatable housing 3 is connected for rotation with torque input means in the form of a crankshaft 10 by way of a flex plate 12. The flex plate 12 carries a starter ring gear 13 and is secured to the housing 3 by way of bolts 14 and to the crankshaft by way of bolts 15. Output shaft 8 is rotatably supported in housing 3 by means of a bearing 16.

A direct coupling clutch 17 operates to connect the input drive to housing 3 directly to the turbine 7 and thus to the output shaft and is used generally at higher engine speeds to avoid the power loss inevitably associated with the fluid coupling 1. The direct coupling clutch comprises a clutch receiving member 18 secured to the turbine 7 and rotatable therewith and a clutch friction plate 19 provided with an annular friction member 20 engageable with the clutch receiving member 18. The clutch friction plate 19 is mounted on the output shaft 8 by way of a bearing 27 which permits the clutch friction plate to rotate relative to the shaft 8 and to slide axially along the shaft 8 when the friction member 20 is moved into or out of engagement with the clutch receiving plate 18 by the application of fluid pressure along a control duct 21 provided internally of the output shaft 8.

A plurality of stubs 22 (four as shown in the drawings) project from an end wall of the housing 3 and a weight 23 is pivotally mounted on each stub 22 by way of a bush 24.

The linking elements in the .form of weights 23 are also slidable axially with respect to the stubs 22 to permit movement during engagement or disengagement of the direct clutch coupling. As. can be seen from Figure 2 the weights 23 are generally triangular in shape and are pivoted on the stubs 22 substantially at their apices. However, other configurations of weights can be employed if desired.

Linking elements 25 are pivotally mounted at one end thereof on weights 23 at a point remote from the bush 24.

The other end of linking elements 25 is pivotally mounted on a stub 26 which is provided on the clutch friction plate 19.

When the direct coupling clutch is engaged by the application of fluid pressure along control duct 21, torque is transmitted to the turbine 7 and thus to the output shaft 8 by way of the housing 3, stubs 22, weights 23, linking elements 25, stubs 26, clutch friction plate 19, annular friction member 20 and clutch receiving member 18.

Damping during engagement and disengagement of the direct coupling clutch, and when the clutch is engaged, is provided by two means. Because the weights 23 are mounted in hydraulic fluid in a relatively restricted space, hydraulic damping functions to resist movement of the weights relative to the housing 3. Additionally, as the rotational speed of the housing 3 increases, centrifugal force acts progressively on the weights 23 making it progressively more difficult to deflect the weights.

However, because the direct coupling to the clutch receiving member 18 passes through the weights 23, deflection of the weights will occur as the torsional forces vary, but the degree deflection is dependent on the rotational speed of the housing thus providing means for absorbing or compensating for torsional fluctuations which is variable in its effect depending on the rotational speed of the engine.

The torque transmitting arrangement shown in Figure 3 is similar to that shown in Figures 1 and 2 and the sane reference numerals are used to denote the same or similar parts.

In the embodiment shown in Figure 3 there is no separate clutch receiving member 18 and instead a clutch receiving surface 28 is formed on the internal surface of one end of the housing 3. Clutch friction plate 19 remains rotatably mounted on output shaft and is slidable axially along the shaft to move the friction member 20 into and out of engagement with the clutch receiving surface 28 by the application of fluid pressure along control duct 21. Stubs 22 project from clutch friction plate 19 instead of from housing 3 and a linking element in the form of a weight 23 is pivotally mounted on stub.22 by way of bush 24 so as to be slidable axially along stub 22.Linking element 25 is pivotally mounted on weight 23 at a point remote from bush 24 and the other end of linking member 25 is pivotally mounted on stub 26 which in this case is provided on turbine 7 rather than on clutch friction plate 19.

Thus in the embodiment shown in Figure 3 the clutch friction plate 19 is caused to rotate by rotation of the turbine 7 rather than by rotation of housing 3. However, the operation of the embodiment shown in Figure 3 is functionally equivalent to the operation of the embodiment shown in Figures 1 and 2.

The direct coupling clutch according to the present invention allows a large angle of deflection with a damping effect that is variable depending on the rotational speed of the clutch while at the same time the construction of the clutch remains relatively simple and is therefore economic to manufacture. The torsional stiffness of the torque transmitting arrangement is at its minimum when the clutch is engaged and increases with increasing engine speed. Thus the transmission can be designed to minimise shock loads when the clutch engages whilst avoiding excessive angular deflections at higher engine speeds.

While the elements 23 are described as weights, the mass of the elements 23 may be selected in dependence on the damping effect required. In some circumstances the elements 23 may have the same or similar mass as elements 25.

Claims

1. A torque transmitting arrangement incorporating a direct coupling clutch, which arrangement comprises a fluid coupling including torque input means to an impeller and torque output means from a turbine, and a direct coupling clutch comprising a clutch friction plate including a friction member which is engageable directly or indirectly with one of the torque input means and the torque output means, a first linking element pivotally connected to the other of the torque input means and the torque output means, and a second linking element pivotally connected to the clutch friction plate and to the first linking element.

2. A torque transmitting arrangement as claimed in claim 1, wherein the friction member is engageable with a clutch receiving plate secured to the turbine.

3. A torque transmitting arrangement as claimed in claim 2, wherein the first linking means is pivotally connected to a housing which is rotatable with the impeller.

4. A torque transmitting arrangement as claimed in claim 2 or 3, wherein the first linking means has a greater mass than the second linking means.

5. A torque transmitting arrangement as claimed in claim 2,3 or 4, wherein the pivotal mounting of the first linking means is located radially inwardly of the pivotal mounting of the second linking means.

6. A torque transmitting arrangement substantially as hereinbefore described with reference to, and as shown in, Figures 1 and 2 of the accompanying drawings.

7. A torque transmitting arrangement as claimed in claim 1, wherein the friction member is engageable with a housing which is rotatable with the impeller.

8. A torque transmitting arrangement as claimed in claim 7, wherein the first linking means is pivotally connected to the turbine.

9. A torque transmitting arrangement as claimed in claim 7 or 8, wherein the second linking means has a greater mass than the first linking means.

10. A torque transmitting arrangement as claimed in claim 7,8 or 9, wherein the pivotal mounting of the second linking means is located radially inwardly of the pivotal mounting of the first linking means.

11. A torque transmitting arrangement substantially as hereinbefore described with reference to, and as shown in, Figure 3 of the accompanying drawings.