WO2010035030A9

WO2010035030A9 - Actuation system

Info

Publication number: WO2010035030A9
Application number: PCT/GB2009/051240
Authority: WO
Inventors: Jonathan C. Wheals
Original assignee: Ricardo Uk Limited
Priority date: 2008-09-24
Filing date: 2009-09-23
Publication date: 2010-07-15
Also published as: GB0817503D0; WO2010035030A3; WO2010035030A2

Abstract

The actuation mechanism (100) includes an actuator beam (102), a reaction element (106) or driver intended to act on the actuator beam, and an output member movable to apply or release an actuating force in response to operation of the actuator beam. The actuator beam (102) lis a spring element and the actuation mechanism is configured to provide relative movement between the driver and the spring element, in order to change the flexed shape of the spring element. Changes in the flexed shape of the spring element result in a change in the actuating force to be applied through the output member.

Description

Actuation System

The present invention relates to an actuation system, particularly, but not exclusively, to an actuation system for actuating clutches or transmission brakes in vehicles.

Clutch actuation systems are known in which a rigid lever of fixed length is arranged to pivot about a fulcrum in order to apply or release force through a thrust bearing, so as to open or close the clutch.

US7, 124,871 describes a known system in which the lever is used to apply an actuating force to the clutch. A first end of the lever is arranged to act on a thrust bearing and a second end of the lever is attached to a grounded energy store, in the form of a spring. In use, the position of the fulcrum is movable so as to change the actuating force. In particular, movement of the fulcrum in the direction of the thrust bearing increases the actuating force, in order to close the clutch. The system is also applicable to transmission brakes.

It is an object of the invention to provide an alternative or improvement to the system described above.

According to one aspect of the invention, there is provided an actuation mechanism for controlling an auxiliary device, for example a clutch or brake, the actuation mechanism including an actuator beam, a reaction element or driver intended to act on the actuator beam, and an output member movable to apply or release an actuating force in response to operation of the actuator beam, wherein the actuator beam is in the form of a spring element and the actuation mechanism is configured to provide relative movement between the driver and the spring element, in order to change the flexed shape of the spring element.

Changes in the flexed shape of the spring element will result in a change in the actuating force to be applied through the output member. The spring element is preferably of known shape and force characteristic, whereby relative movement between the driver and the spring element beam can be used to bring about a predetermined change in the flexed shape of the spring element. This affords controlled modulation of the actuating force, unlike the rigid lever systems described in US7,124,871.

Moreover, the use of an actuator beam in the form of a spring element, as opposed to a rigid lever, obviates the need for the energy store used in the systems described in US7, 124,871, and so provided a simplified assembly.

The spring element can be designed for specific applications. In clutch applications, the spring element can be designed to overcome the disadvantageous non-linear nature of pressure plate diaphragm springs and/or non- linear clutch loads associated with dry clutches, for example.

The spring element may include localised work hardening and/or areas of surface treatment (e.g. areas of nitride treatment), which are intended to influence the force characteristic of the spring element, e.g. to provide non-homogeneous spring characteristics.

The auxiliary device is preferably a clutch in a vehicle, in which case the output member is preferably a thrust bearing or similar device arranged for movement in a first direction to close the clutch and a second direction to open the clutch. In other embodiments, the auxiliary device may be a transmission brake in a vehicle or a more general force-return device, such as a piston, in automotive and/or non-automotive applications.

The output member may form part of the auxiliary device.

The spring element preferably has a second end arranged for cooperation with a grounded element, e.g. part of a transmission casing, clutch housing or other adjacent grounded surface. In such embodiments, the driver is intended for contact with the spring element to provide a reaction against the bias of the spring element, and is preferably movable relative to the spring element, in order to change the flexed shape of the spring element, and thereby change the output force from the spring element to the output member.

In other embodiments, the second end of the spring element may be coupled (directly or indirectly) with an actuator intended to push or pull the second end of the spring element. In such embodiments, the driver is also intended for contact with the spring element, but is preferably fixed relative to the spring element, e.g. mounted on a grounded element such as a transmission casing, clutch housing or other adjacent grounded surface. In such embodiments, the driver provides a grounded reaction to the movement of the spring element (when in contact therewith), to bring about a change in the flexed shape of the spring element and, hence, change the output force experienced by the output member.

In all embodiments, the driver preferably includes a roller arranged for contact with the spring element.

A rate-varying element may be provided, against which the spring element is intended to be deformed (e.g. arranged between the driver and the spring element and/or between the spring element and the output member), in order to bring about change in the output force characteristic. The rate-varying element preferably has a predetermined profile or resilient characteristic, in order to introduce specific loads.

The mechanism may include a plurality of drivers, each arranged for varying the force output from the beam. In one embodiment, the mechanism includes opposing drivers arranged to act on respective sides of the spring element (e.g. a first driver acting on one side of the beam and a second driver acting on the opposite side of the beam).

Each driver is preferably movable along an associated guide surface. In such embodiments, it may be preferred to replace the spring element with a rigid lever element of known profile.

The spring element or lever preferably defines first and second actuation zones, wherein the profile of the second actuation zone differs from the profile of the first actuation zone. In preferred embodiments, a first driver is arranged to act on the first actuation zone and a second driver is arranged to act on the second actuation zone. The second actuation zone preferably defines a less acute profile than the first actuation zone, so as to provide for fine adjustment of the output force experienced by the output member compared to the first actuation zone.

According to a further aspect of the invention, there is provided a method of operating a clutch or transmission brake using a spring element, a driver intended to act on the spring element, and an output member movable in response to movement of the spring element in order to apply or release an actuating force, and providing relative movement between the spring element and the driver, in order to change the actuating force to be applied through the output member to the clutch or transmission brake.

According to another aspect of the invention, there is provided an actuation mechanism including a spring element and a reaction element or driver intended to act on the spring element, and an output member movable to apply or release an actuating force in response to operation of the spring element, wherein the actuation mechanism is configured to provide for relative movement between the driver and the spring element, in order to change the flexed shape of the spring element.

Other aspects and preferred features of the invention will be readily apparent from the claims and following description of preferred embodiments, made by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a schematic cross-section through part of an actuation mechanism, which includes a movable reaction member for an actuator beam in the form of a spring element;

Figure 2 is a modified embodiment of the mechanism of Figure 1;

Figure 3 is a further modified embodiment of the mechanism of Figure 1;

Figure 4 is a schematic perspective view of further actuation mechanism; Figure 5 is a schematic cross-section through part of an actuation mechanism, which includes a fixed reaction member for an actuator beam in the form of a spring element;

Figure 6 is a modified embodiment of the mechanism of Figure 5; and

Figure 7 is a schematic illustration of an actuation mechanism using a plurality of movable drivers to act on a single actuator beam (spring element or rigid lever)

Referring firstly to Figure 1, an actuating mechanism for a clutch or transmission brake is indicated generally at 100.

The actuating mechanism 100 includes an actuator beam 102 in the form of a spring element of known shape and force characteristic, herein after referred to as the spring beam 102. The spring beam 102 is arranged for cooperation with a thrust bearing 104, in order to apply or release a force through the thrust bearing 104.

The thrust bearing 104 is arranged for reciprocal movement along a linear thrust axis T, for opening or closing the clutch or transmission brake. In preferred embodiments, the thrust axis T is defined by a shaft, wherein the thrust bearing 104 is arranged for reciprocal movement along said shaft.

The actuating mechanism 100 includes a driver 106 arranged for cooperation with the spring beam 102. In particular, the driver 106 is intended to act on the spring beam 102, in order to change the force applied through the thrust bearing 104.

In the embodiment of Figure 1, the spring beam 102 is supported between the thrust bearing 104 (see point C in Figure 1), the driver 106 (see point B in Figure 1) and a ground element 108 (see point A in Figure 1) which is fixed relative to the thrust axis T. As illustrated, the spring beam 102 is arranged in a flexed state, and so assumes a flexed shape which is different to its natural free shape.

The driver 106 is movable relative to the spring beam 102, wherein movement of the driver 106 brings about change in the flexed shape of the spring beam 102. It will be understood that a change in the flexed shape of the beam 102 will result in a change in the output force from the spring beam 102 to the thrust bearing 104, dependent upon the profile and force characteristics of the spring beam 102.

In the majority of cases, movement of the driver 106 in a first direction towards the thrust bearing 104 will result in an increase in the output force from the spring beam 102, whereas movement of the driver 106 in a second direction (opposite to said first direction) away from the thrust bearing 104 will result in a reduction in the output force from the spring beam 102, e.g. for closing or opening a clutch or transmission brake, respectively.

It will be understood that the spring beam 102 effectively replaces the rigid lever and energy store of the known actuating mechanisms described and illustrated in the prior art and so provides a more simple assembly. Moreover, the tuning of the spring beam 102 can be selected to provide predetermined output force modulation characteristic for a given travel of the driver 106.

The driver 106 is preferably reciprocal along a drive axis D, e.g. orthogonal to the thrust axis T. In Figure 1, the driver 106 is movable along a track or guide surface 110, which preferably defines the drive axis A. The guide surface 110 is preferably grounded relative to the spring beam 102.

In this embodiment, the driver 106 is arranged in direct contact with the spring beam 102. Hence, if the driver 106 moves along the grounded guided surface 110, the flexed profile of the spring beam will be altered, thereby changing the output force from the spring beam 102. As illustrated, it may be preferable for the grounded guide surface 110 to be integral with or connected to the ground element 106 for the spring beam 102.

The driver 106 preferably includes one or more rollers 112. In a simplified embodiment (not illustrated), a single roller is arranged in contact between the guide surface 110 and the spring beam 102. However, the driver 106 may take the form of a bogey having two rollers 112 for cooperation with the guide surface 110 and a third roller 112 for cooperation with the spring beam 102, e.g. as shown in Figures 1 to 3

(in which the two rollers 112 are in rolling contact with the guide surface 110 and the third roller 112 is in rolling contact with the spring beam 102).

The actuating mechanism 100 may include multiple spring beams 102 (e.g. arranged in a radial array), each having an associated driver 106. The multiple spring beams may be in the form of radial fingers extending from a single disk element.

A variant is shown in Figure 2, wherein a rate- varying element 114 (rigid or resilient) is arranged between the spring beam 102 and the thrust bearing 104. The rate-varying element 114 has a predetermined profile and resilient characteristic, such that, during movement of the driver 106, the spring beam 102 is deformed against the rate-varying element 114, in order to bring about predetermined change in output force characteristic. This may reduce the required length of the spring beam 102, resulting in a more radially compact assembly. The rate-varying element 114 (or an additional rate-varying element) may be arranged between the spring beam 102 and the driver 106.

An example of an alternatively configured spring beam 102 is illustrated in Figure 3, wherein the spring beam includes a convolution at its non-apply end (to the left as viewed in Figure 3), which reduces the required length of the spring beam 102, and so provides a more radially compact assembly. Multiple convolutions may be includes, as desired. In addition, a rigid or resilient rate varying element, e.g. of the kind shown in Figure 2, may be included between the spring beam 102 and the thrust bearing 104 and/or the spring beam 102 and the driver 106. Figure 4 shows a linear actuator 116 arranged in communication with the driver 106. The linear actuator 116 is configured for reciprocating the driver 106, as desired for operation of the clutch or transmission brake. In other embodiment, a rotary actuator may be employed to reciprocate the driver 106.

In the embodiment of Figure 5, the driver 106 is not movable. Instead, the driver 106 is mounted on a grounded element 118, which is fixed relative to the thrust bearing axis A.

As in the embodiment of Figures 1 to 4, the spring beam 102 is of known shape and force characteristic, and a first end of the spring beam 102 is arranged for cooperation with the thrust bearing 104. However, the second end of the spring beam 102 is coupled (directly or indirectly) with a reciprocating actuator 120 intended to push or pull the second end of the spring beam 102.

The driver 106 is arranged to act on the spring beam 102. In use, the driver 106 serves to vary the flexed shape of the spring beam 102 (and, hence, the output force experienced by the thrust bearing 104), as the spring beam 102 is pushed/pulled by the actuator 120. In the embodiment of Figure 5, the driver 106 includes a roller 112 arranged for contact with the spring beam 102.

In the illustrated embodiment, an intermediate linkage 122 is provided between the actuator 120 and the spring beam 102. The spring beam 102 is preferably coupled to the linkage 122 by a pivotable connection 124. The linkage 122 preferably extends through two sets of guide rollers 126.

An adjustment mechanism (not shown) may be provided between the spring beam 102 and the thrust bearing 104, in order to account for free play (e.g. resulting from clutch wear). Such adjustment means may also be provided in the embodiments of Figures 1 to 4. In the case of embodiments using the bogey-type drivers of Figures 1 to 4, adjustment means (e.g. sprung ratchet ramps of known form, may be incorporated within the bogey, such that the bogey is able to expand (vertically as shown in Figure 1) and so take up wear. A variant is shown in Figure 6, wherein a rate- varying element 128 (rigid or resilient) is provided between the driver 106 and the spring beam 102. The rate-varying element 128 preferably has a predetermined profile or resilient characteristic, in order to introduce specific loads. The may reduce the required length of the spring beam 102, resulting in a radially compact assembly.

The embodiment of Figure 7 includes opposing drivers 108 arranged with respective side of a spring beam 102 of known shape and force characteristic. Each driver 106 has an associated guide surface 110 and is selectively reciprocal along its guide surface under the action of an associated actuator 116 (via a linkage 122).

The spring beam 102 in embodiments of the kind shown in Figure 7 may be replaced by a rigid lever element of known profile.

The spring beam or lever preferably defines first and second actuation zones, wherein the profile of the second actuation zone differs from the profile of the first actuation zone. In preferred embodiments, a first driver is arranged to act on the first actuation zone and a second driver is arranged to act on the second actuation zone. The second actuation zone preferably defines a less acute profile than the first actuation zone, so as to provide for fine adjustment of the output force experienced by the output member compared to the first actuation zone. This can be used to modulate clutch slip, for example.

It will be understood that the industrial application of the actuating mechanisms described above is not limited to clutches or transmission brakes in vehicles.

Claims

1. An actuation mechanism for controlling a clutch or brake, the actuation mechanism including an actuator beam, a reaction element or driver intended to act on the actuator beam, and an output member movable to apply or release an actuating force in response to operation of the actuator beam, wherein the actuator beam is a spring element and the actuation mechanism is configured to provide relative movement between the driver and the spring element, in order to change the flexed shape of the spring element, wherein changes in the flexed shape of the spring element result in a change in the actuating force to be applied through the output member.

2. An actuating mechanism according to claim 1 wherein the output member is arranged for reciprocal movement along a thrust axis.

3. An actuating mechanism according to claim 2 wherein the driver is reciprocal along a drive axis D orthogonal to the thrust axis T.

4. An actuation mechanism according to any of claims 1 to 3 wherein the driver includes a roller arranged for contact with the spring beam.

5. An actuation mechanism according to any preceding claim wherein the driver is movable along a grounded surface or track.

6. An actuating mechanism according to claim 5 wherein driver takes the form of a bogey having two rollers in contact with a track or guide surface and a third roller in contact with the spring beam.

7. An actuating mechanism according to claim 5 or claim 6 wherein the spring beam is simply supported between the output member and the ground element.

8. An actuation mechanism according to any preceding claim wherein the spring beam has a second end arranged for cooperation with a ground element, and the driver is movable relative to the spring beam, whereby movement of the driver relative to the spring beam brings about a change in the output force from the spring beam to the output member.

9. An actuation mechanism according to any of claims 1 to 4 wherein the second end of the spring beam is coupled (directly or indirectly) with an actuator intended to push or pull the second end of the spring beam, and the driver is fixed relative to the spring beam and serves to vary the flexed shape of the spring beam during movement of the actuator.

10. An actuation mechanism according to any preceding claim wherein a rate- varying element is provided, against which the spring beam is intended to be deformed, in order to bring about change in the output force characteristic.

11. An actuation mechanism according to any preceding claim wherein the output member forms part of the auxiliary device.

12. An actuation mechanism according to any preceding claim including a plurality of drivers, each arranged for varying the force output from the beam.

13. An actuation mechanism according to claim 12 wherein the mechanism includes opposing drivers arranged to act on respective sides of the spring beam.

14. An actuation mechanism according to claim 12 or claim 13 wherein the spring beam defines first and second actuation zones of different profiles, a first driver arranged to act on the first actuation zone and a second driver arranged to act on the second actuation zone, and wherein the second actuation zone defines a less acute profile than the first actuation zone, so as to provide for fine adjustment of the output force experienced by the output member compared to the first actuation zone.

15. A method of operating a clutch or transmission brake using a spring beam, a driver intended to act on the spring beam, and an output member movable in response to movement of the spring beam in order to apply or release an actuating force, and providing relative movement between the spring beam and the driver, in order to change the actuating force to be applied through the output member to the clutch or transmission brake.

16. A control assembly for a clutch or brake, the control assembly incorporating an actuation mechanism according to any of claims 1 to 14 for controlling said clutch or brake.

17. A vehicle incorporating a clutch or brake and an actuation mechanism according to any of claims 1 to 14 for controlling said clutch or brake.

18. An actuation mechanism including a spring element and a reaction element or driver intended to act on the spring element, and an output member movable to apply or release an actuating force in response to operation of the spring element, wherein the actuation mechanism is configured to provide for relative movement between the driver and the spring element, in order to change the flexed shape of the spring element.

19. An actuating mechanism according to claim 18 wherein the output member is arranged for reciprocal movement along a thrust axis.

20. An actuating mechanism according to claim 19 wherein the driver is reciprocal along a drive axis D orthogonal to the thrust axis T.

21. An actuation mechanism according to any of claims 18 to 20 wherein the driver includes a roller arranged for contact with the spring beam.

22. An actuation mechanism according to any of claims 18 to 21 wherein the driver is movable along a grounded surface or track.

23. An actuating mechanism according to claim 22 wherein driver takes the form of a bogey having two rollers in contact with a track or guide surface and a third roller in contact with the spring beam.

24. An actuating mechanism according to claim 22 or claim 23 wherein the spring beam is simply supported between the output member and the ground element

25. An actuation mechanism according to any of claims 18 to 24 wherein the spring beam has a second end arranged for cooperation with a ground element, and the driver is movable relative to the spring beam, whereby movement of the driver relative to the spring beam brings about a change in the output force from the spring beam to the output member.

26. An actuation mechanism according to any of claims 18 to 21 wherein the second end of the spring beam is coupled (directly or indirectly) with an actuator intended to push or pull the second end of the spring beam, and the driver is fixed relative to the spring beam and serves to vary the flexed shape of the spring beam during movement of the actuator.

27. An actuation mechanism according to any of claims 18 to 26 wherein a rate- varying element is provided, against which the spring beam is intended to be deformed, in order to bring about change in the output force characteristic.

28. An actuation mechanism according to any of claims 18 to 27 wherein the output member forms part of the auxiliary device.

29. An actuation mechanism according to any of claims 18 to 28 including a plurality of drivers, each arranged for varying the force output from the beam.

30. An actuation mechanism according to claim 29 wherein the mechanism includes opposing drivers arranged to act on respective sides of the spring beam.

31. An actuation mechanism according to claim 29 or claim 30 wherein the spring beam defines first and second actuation zones of different profiles, a first driver arranged to act on the first actuation zone and a second driver arranged to act on the second actuation zone, and wherein the second actuation zone defines a less acute profile than the first actuation zone, so as to provide for fine adjustment of the output force experienced by the output member compared to the first actuation zone.

32. A control assembly for a clutch or brake, the control assembly incorporating a spring element and a reaction element or driver intended to act on the spring element, wherein the control assembly is configured to provide for relative movement between the driver and the spring element, in order to change the flexed shape of the spring element, and the control assembly further including an output member movable to apply or release an actuating force for the clutch or brake in response to operation of the spring element.

33. A control assembly according to claim 32 wherein the spring element, driver and output member form part of an actuation mechanism in accordance with any of claims l to 14 or 18 to 31.