192 clutches and power-stop control – Clutches – Operators
Reexamination Certificate
2000-09-11
2002-08-20
Bonck, Rodney H. (Department: 3681)
192 clutches and power-stop control
Clutches
Operators
C192S090000
Reexamination Certificate
active
06435327
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a disengaging device for a clutch. Such disengaging devices are installed in many different ways in the driving trains of different assemblies to accomplish a disengaging movement. Such disengaging devices are especially employed as force converters in order to translate a manually exerted force, or a force exerted in a defined direction, into a force that is mechanically directed in a defined way. Such disengaging devices can release clutches of motor vehicles.
2. The Prior Art
Such a disengaging device is known from DE 38 06 642 A1. This disengaging device has an energy storage means which supplies energy in the disengaging process, and which stores energy in a reversed process. The forces required for such a disengagement process are thus reduced. Such a disengaging device is especially suited for mechanical devices that can be disengaged only against relatively high resetting forces.
Two springs arranged perpendicular to a disengaging piston act as the energy storage means for this known disengaging device. The springs interact with an antifriction bearing serving as the force-coupling element, which is guided on the disengaging piston along a substantially conical, curved track. Depending on the existing wear, an assembly supporting the curved track can be displaced along the disengaging piston. It is possible to take into account wear of the clutch or similar displacement movements that occurred over long periods of time. Such an assembly is displaced in proportion to the traveling distance of the disengaging piston.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a disengaging device for a clutch, with an energy storage means that supplies energy in the disengagement process, and stores energy in a reversed process. It is possible with this device to adapt the storage of energy to all kinds of different situations in a relatively simple way.
The invention proposes a disengaging device of the type specified above that increases the energy in the energy storage in dependence upon a force occurring in the disengaging device. This is accomplished by a hydraulically or pneumatically actuated punch having a variable active surface.
By varying the active surface in dependence on the distance of disengagement of the punch, the characteristic by which the punch increases the energy in the energy storage means as a result of the force occurring in the disengaging device, can be readily adapted to the given requirements. As compared to the solution as defined by the invention, it was found that attempts to adapt such a characteristic using plate springs, sets of springs, or individual springs, require substantially more difficult coordination, and also lead to relative instability with respect to the structure of the device, or to relatively large volumes of the structure of such a device.
The increase in energy can be made directly dependent upon the force occurring in the disengaging device if the punch is actuated by a disengaging hydraulic or pneumatic system that is prompted into action by the disengaging device. In such an arrangement, a change in pressure in the hydraulic or pneumatic system conditions an effect that is directly acting on the punch. Such an arrangement was found to be particularly advantageous for the area of the clutch where hydraulic or pneumatic systems are regularly employed between the disengaging device and the clutch. In particular, clutch wear leads to an increase in the pressure in the hydraulic or pneumatic system, which causes an effect acting on the punch and consequently a rise of the energy in the energy storage means.
In one embodiment of the invention, the punch can be sealed against a guide surface having a directional component pointing away from or in the direction of the punch. The consequence of such an arrangement is a variable active surface that is conditioned by the seal. The size of the active surface changes depending on the directional component of the guide surface that is pointing away from or in the direction of the punch. Depending on the position of the punch along its path of travel, the guide surface is consequently disposed either closer to or farther from the punch. Conditioned by the seal, the hydraulic or pneumatic pressure is therefore acting on a larger or, respectively, a smaller surface, the result being that the overall force acting on the punch is higher or lower accordingly.
In particular, the punch may be guided in a space which has a cross section that varies along the traveling path of the punch. Preferably, the variation in the cross section takes place symmetrically in relation to an axis of symmetry of the punch, so that the punch will be loaded as uniformly as possible.
The punch can be arranged in an annular gap whose radially inner wall and/or radially outer wall varies along the path of travel of the punch. With such an arrangement, the punch is formed ring-shaped. This offers the advantage of an especially compact design, particularly with substantially linear disengaging devices such as a hydraulic or pneumatic disengaging piston. If the wall varies along the path of travel of the punch, the direct result thereof is a variation in the width of the annular gap along the path of the punch, which results in a corresponding variation of the active surface.
In particular, it is advantageous if both the radially inner wall and the radially outer wall are varied along the path of travel of the punch. Such a variation can be selected so that the active surface of the punch changes symmetrically with respect to the punch, so that the punch is evenly loaded. Canting of the punch can thus be avoided with this design.
Sealing of the punch, so that it can be acted upon hydraulically or pneumatically, can be accomplished with a sealing ring that seals a gap located between the punch and the wall via a sealing lip. The sealing lip is capable of following a change in the width of the gap and in that way permits a variable active surface of the punch.
If a sealing ring with a U-shaped profile is used as the sealing element, the punch can be made inexpensively because it is possible to use a standard-type grooved ring.
The force acting on the punch or on the seal is distributed evenly if the sealing ring with a U-shaped profile abuts a wall with each of its legs. Especially in conjunction with such an application of the seal, it is advantageous if the walls abutted by each of the legs vary evenly, so that the ratios of the force acting on the sealing ring will be uniform as well.
If such a sealing ring is employed, it only needs to rest on a readjusting piston of the punch, so the disengaging device can be built in a relatively simple way.
Furthermore, the disengaging device may comprise means for measuring the distance traveled by the punch. Irrespective of the way in which the punch is actuated, this makes it possible to determine the force occurring in the disengaging device. This force may be the measure for any wear of the clutch, or a measure for similar purposes. It is thus possible to indirectly obtain information about any wear of the clutch at low cost, and to assure replacement of the clutch in due time.
Preferably, the holding means prevents the punch from traveling back into its starting position when the force is reduced. This assures that in spite of any reduction in the force, as it regularly occurs with such disengaging devices, the punch will remain in a position corresponding with the maximal force. To that extent, the punch provides an indication as to what the status of the clutch is at any time with respect to wear or similar conditions. Moreover, the holding means assures that a rise in energy in the energy storage can take place in a continuous way.
In particular, the holding means may comprise a hydraulic or pneumatic check valve. Instead, or in addition, there may also be a locking device. This locking device may comprise spring tongues that engage behind a stop means
Heidingsfeld Dietmar
Rohs Ulrich
Bonck Rodney H.
Collard & Roe P.C.
Rohs-Voigt Patentverwertungs-gesellschaft mbH
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