WO2005042997A1

WO2005042997A1 - Retaining actuator for a mechanical device and controllable friction clutch provided with said actuator

Info

Publication number: WO2005042997A1
Application number: PCT/AT2004/000377
Authority: WO
Inventors: Gert Krammer
Original assignee: Magna Steyr Fahrzeugtechnik Ag & Co Kg
Priority date: 2003-10-31
Filing date: 2004-10-29
Publication date: 2005-05-12
Also published as: AT7580U1

Abstract

A mechanical device, more particularly a controllable friction clutch, comprising a retaining actuator consisting of a primary part (10), a secondary part (11) with a secondary shaft and secondary disks with a pressure plate (12) and a spring (18), in addition an actuator (1) with a radial cam. In order that the actuator can maintain each position without any external force, the radial cam (23, 24) and/or the body (21, 22) has a number of discontinuities (40; 59; 70; 83) that form a quantity of local minima (41) corresponding to the retaining positions of the actuator (1). The discontinuities (40) of the radial cam (23, 24) are mountains (40) and valleys (41), wherein the restoring forces in the valleys (41) are smaller than those in the adjacent mountains (40).

Description

HOLDING ACTUATOR FOR A MECHANICAL DEVICE AND CONTROLLABLE FRICTION CLUTCH WITH SUCH A

The invention relates to a holding actuator for a mechanical device, which has a motor and at least one transmission member, which converts a rotational movement into a translational movement / force by means of a control cam and a body interacting therewith, which translational force against the force of a spring on the mechanical device acts. The mechanical device can be a window lifter, a seat adjustment or any auxiliary mechanism in a motor vehicle, in particular a controllable friction clutch, which essentially consists of a primary part with a primary shaft and primary plates, a secondary part with a secondary shaft and secondary plates and a pressure plate, which is the primary - Presses and secondary plates against the force of a spring or several springs in a frictional connection, and wherein the actuator exerts a translatory force on the pressure plate. On adjustment mechanisms, especially on controllable clutches in the

Powertrain for motor vehicles has special requirements. Among other things, they must be able to be fixed after the setting has been made - in the case of a clutch in particular to a specific torque to be transmitted - that is to say to maintain their position even when subjected to force. In certain situations, clutches must also be able to be controlled or switched quickly.

There are generally three ways to hold a force setting

Possibilities: - First: The transmission mechanism is self-locking, such as a high-gear worm gear. However, this significantly reduces efficiency and requires a larger, more powerful motor. Fast adjustment requires additional measures. - Second: The motor remains energized in the respective position, a holding current. Although it is smaller, it must be set very precisely. - Third: An additional brake, which increases the construction work considerably and has to be controlled specifically.

So all three options are unsatisfactory, regardless of the type or design of the servomotor.

It is therefore the object to be achieved by the invention to propose an actuator which allows the position that has been approached to be held under load in the simplest possible manner without the above disadvantages. According to the invention, this is achieved in that the control curve or the body has a number of discontinuities which, in the course of the restoring force exerted by the at least one spring and depending on the position of the actuator, bring about a number of local minima to which holding positions correspond. Where, according to the prior art, external forces paid for with electric current have to be used for holding, the restoring forces of the springs already present in the mechanical device itself are used for holding according to the flash of thought on which the invention is based. In terms of energy, these restoring forces have a potential, the value of which varies depending on the actuator position. The potential is a minimum in the initial position (especially when the clutch is fully open). The further the adjustment against spring force has taken place (the more closed the clutch), the higher the potential. Depending on the direction of action of the spring, the conditions can also be reversed.

When using a control curve somewhere in the actuator, this has an essentially constant course between the maximum and the minimum according to the prior art. This is where the invention comes in. If small local minima - intermediate minima, so to speak - are created in between, the actuator holds its position even in these intermediate positions without external force. Operating forces are then necessary in order to overcome the mountains adjoining the intermediate minimum. They don't have to be high. As long as there are only enough such intermediate minima, there are enough possible stopping positions and vibrations with larger positioning movements can also be avoided by appropriate selection of the speed of the servomotor.

There are various ways to implement this basic idea. One is to give the body rolling on the control curve a polygonal contour (claim 2). If an existing actuator after the State of the art already provides a body rolling on a control curve, it only needs to be polygonalized.

Another way is to provide the control curve with discontinuities that form mountains and valleys, the restoring forces in the valleys being smaller than on the neighboring mountains (claim 3). In this case, the body can simply slide on the control curve. But a rolling body is also possible. There is great freedom in the choice of the shape of these valleys according to the kinematic and specific requirements.

Finally, as a middle path, the control curve and the body may also have discontinuities, the control curve may have stair-shaped discontinuities and the body rolling on the control curve may have a polygonal contour (claim 4). Then the distances and contours on the two interacting parts must be coordinated and the height of the mountains can be adjusted by rounding off the edges.

Put simply, the control curves can be on one level or on a cylinder jacket, depending on the kinematic requirements of the actuator and the space available. Then the control curve lies either in an axis-normal plane rotating about an axis (claim 5), whereby for the actuation of the scissor levers two ramp rings, as are often used to convert a rotary movement into a linearly acting large force, in particular in the axis-normal plane two against - offset control cams are provided (claim 6), or the control curve lies on a generated by a rotating about an axis generating surface, in particular a cylindrical surface (claim 7). The ramp rings with balls in between can be viewed as such an imaginary surface area. The idea of the invention can thus be applied to actuators of the most varied types; both in those with an engaging lever (claim 8) acting on the mechanical device (in particular the pressure plate of a friction clutch), as well as in those with a rotatable drum carrying the control cam as a transmission member without rotatable ramp rings (claim 9), or also with rotatable ones Ramp rings, the ramps themselves are designed as the control curves (claim 10). This means that the shape of the control curve or the body according to the invention can be used at actuators with several transmission elements at different points. In particular, the mechanical device is the pressure plate of a friction clutch (claim 11).

The invention is described and explained below with the aid of illustrations of an application example of the actuator according to the invention, namely a friction clutch. 1: a first embodiment, FIG. 2: a second embodiment, FIG. 3: detail A in FIG. 1, clearly showing the invention, likewise FIG. 4: detail B in FIG. 1, first variant 5: detail B in FIG. 1, second variant, FIG. 6: detail B in FIG. 1, third variant, FIG. 7: comparison of the potential curves.

In Fig. 1, the actuator is summarized with 1 and the clutch with 2. The actuator 1 is composed of a servomotor 4 controlled by a control unit 3, a transmission mechanism 5 (for example a reduction gear) and an actuator 6, with means a certain contact pressure or a certain torque to be transmitted is set on the clutch 2. The torque to be transmitted by the clutch 2 is determined by the control unit 3 from driving dynamics variables and is set accordingly via the current supply to the servomotor 4.

The clutch 2 itself, a multi-plate or multi-disc clutch, is only shown schematically because of the usual design. It consists of a primary part 10 with a primary shaft and primary plates and a secondary part 11 with a secondary part and secondary plates. The alternating lamellae of both parts 10, 11 can be pressed together by means of a pressure plate 12, on which an actuator 6 acts. The actuator 6 here consists of a first ramp ring 13 and a second ramp ring 14 with an intermediate roller body, for example balls, 15. With 16, 17, pressure bearings are indicated which support the ramp rings with respect to non-rotating parts or parts rotating at a different speed.

The ramp rings 13, 14, or, at least one of the two, have ramps which are not yet visible in FIG. 1 and whose gradient runs in the circumferential direction. These ramps represent control curves which are in an imaginary cylinder with the axis of the coupling as the axis and a generatrix 26 drawn in dashed lines. This generatrix generates an imaginary cylinder jacket which is unrolled into the image plane in the representations of FIGS. 4 to 6.

Compression springs 18 acting in the release direction are arranged between the plates of the clutch. To increase the transmitted torque, the pressure plate 12 presses the lamellae against the force of these springs 18. Instead of the springs between the plates of the clutch, te a single clutch spring can also be provided. Arms 19, 20 are located on the ramp rings 13, 14, at the ends of which bodies 21, 22 are arranged, which interact with control cams 23, 24 formed on the circumference of a control drum 25.

In the embodiment of FIG. 2, the actuator is designed differently. It consists of a rotating pressure ring 27 with a circumferential groove 28, a two-armed lever 30 which is fixed to the housing at a point 31 and at one end a shift fork with sliding blocks 29 engaging in the annular groove 28 and at the other end a body 32 which cooperates with a disc 34. The disc 34 is set in rotation by an electric motor 4 via a reduction gear 5. On the periphery of the disk 34, a control cam 33 is formed, in which the body 32 of the engagement lever 30 engages or on which it engages.

Fig. 3 shows the control drum 25 of Fig.l in front view. The control curves 23, 24 are designed according to the invention. For comparison, the steady course of the control curve 23 * according to the prior art is shown in broken lines. The control curve 23 according to the invention consists of successive mountains 40 and valleys 41. In one of the valleys 41, the body 21 cooperating with the control curve 23 rests, which can be a sliding body or a rolling body. The body 21 is pressed against the control cam 23 by the springs 18 (FIG. 1) of the clutch 2. It rests in a valley depression 41. To get out of it, it would have to climb over one of these two mountains 40 against the force of the coupling springs 18. It is thus held in this position by the clutch springs as long as no torque emanating from the servomotor 4 acts on the control drum 25. In Fig. 3, two control cams 23, 24 are arranged offset by 180 degrees to each other in order to be able to move the two scissor levers 19, 20 in opposite directions. The two control cams 23, 24 can also be offset from one another in the axial direction. Otherwise, the control drum 25 can be a disk, on the periphery of which the two control cams are formed. If one thinks away the left half of the picture in FIG. 3 and only looks at the control curve 23, one obtains a view in the axial direction of the control disk 34 of FIG. 2.

FIG. 4 shows a possible design of a control curve on an essentially cylindrical surface or in a section after a cylinder, rolled up in the plane of the drawing. The control curve can be the path of one of the two ramp rings 13, 14 of FIG. 1, or another control curve or link from a differently constructed actuator. The control curve 48 here is a continuous curve as in the prior art, to implement the principle according to the invention, the body 49 is polygonal, in the figure as an octagon, it could also be any higher number of sides, the corners 50 of the body 49 the mountains and the areas 51 of the body 49 correspond to the valleys in between.

In Fig. 5, it is the cam 58 that runs in mountains 59 and valleys 60 therebetween. A body 61, which can be a rolling body or a sliding body, cooperates with this control curve 58. In the event that the two ramp rings 13, 14 of FIG. 1 are involved, it is sufficient to execute the control curve only on one ramp ring 14 and to provide a continuously running or even an incline-free path 62 on the other ramp ring 13. The control curve 58 according to the invention could also on the other (13) of the two ramp rings. Such a control cam, which acts when rotating in the direction of the axis of rotation, can also be used in actuators of another type. Since the rolling or sliding body 61 is loaded by the spring 18 of the clutch, a single control cam 58 is then sufficient.

6 shows a further exemplary embodiment in which a control cam 68 is composed of mutually alternating planes 69 and ramps 70 and cooperates with a polygonal rolling body 71. Its polygon sides are as long as the planes 69 and the ramps 70. The angles of the polygon sides also match the angles between the planes 69 and the ramps 70, so that the corners 72 of the polygon at the intersections between plane 69 and ramp 70 when rolling off comes to rest.

7 illustrates the basic idea of the invention. The diagram on the left corresponds to the state of the art and the diagram on the right shows the concept on which the invention is based. In the diagram on the left, the path of the actuator is shown on the ordinate and the potential energy at rest in the restoring forces of the clutch is shown on the abscissa. The curve 80 runs continuously. The curve 81 in the diagram on the right consists of valleys 82 and mountains 83. It can be seen that the valleys 82 have local minima of the potential energy and therefore each valley 82 is a possible holding position of the actuator, in which it is held in its position without external forces is.

Claims

Claims 15

1. Holding actuator for a mechanical device, which has a motor and at least one transmission element, which converts a rotary into a translatory movement / force by means of a control cam and a body interacting with it, which translatory force against the force of a Spring (18) acts on the mechanical device, characterized in that the control cam (23, 24; 33; 58;

25 68) and / or the body (49; 71) have a number of discontinuities (40; 59; 70; 83) which a number in the course of the restoring forces depending on the position of the actuator and exerted by the force of the spring (18) local minima (41; 60; 82), which correspond to the holding positions of the actuator (1).

30 2. Holding actuator according to claim 1, characterized in that the body rolling on the control cam (48; 68) (49; 71) has a polygonal contour (50, 51).

35 3. Holding actuator according to claim 1, characterized in that the control curve (23, 24; 58; 68) has discontinuities (40; 59; 70; 83), the mountains (40; 59; 83) and valleys (41; 60; 82) form, the restoring forces in the valleys being smaller than on the neighboring mountains.

4. Holding actuator according to claim 1, characterized in that the control cam (68) has step-shaped discontinuities (69, 70) and the body (49; 71) rolling on the control cam (68) has a polygonal contour.

5. Holding actuator according to one of claims 1 to 4, characterized in that the control cam (33) lies in an axis-normal plane rotating about an axis.

6. Holding actuator according to claim 5, characterized in that in the axis-normal plane two mutually offset control cams

(23.24).

7. Holding actuator according to one of claims 1 to 4, characterized in that the control cam (48; 58; 68) lies in a lateral surface described by a rotating around an axis generating (26).

8. Holding actuator according to claim 5, characterized in that the actuator as a transmission member has a rotatable cam (34) with a control cam (33), and the cooperating body (32) is attached to an engagement lever (30) on the mechanical device (12) acts. (Fig.2)

9. Holding actuator according to claim 7, characterized in that the actuator as a transmission member has a rotatable drum (25) with at least one link, which forms the control curve (23, 24; 48; 58; 68) and which cooperates with it at least one body (21, 22) is each fastened to a lever (19, 20) which is firmly connected to one of two ramp rings (13, 14) which can be rotated relative to one another.

10. Holding actuator according to claim 7, characterized in that the actuator as a transmission member has a rotatable drum (25) with at least one link, and the cooperating with it at least one body (21, 22) each on a lever (19, 20) is fixed, which is fixedly connected to one of two mutually rotatable ramp rings (13, 14), and the ramps of the ring are designed as the control cams (48; 58; 68).

11. Controllable friction clutch with a holding actuator according to one of the preceding claims, wherein the friction clutch in

Essentially it consists of a primary part (10) with primary shaft and primary plates, a secondary part (11) with secondary shaft and secondary plates and a pressure plate (12) which presses the primary and secondary plates against the force of at least one spring (18) in a frictional connection.