192 clutches and power-stop control – Clutches – Operators
Reexamination Certificate
1999-10-12
2001-06-05
Bonck, Rodney H. (Department: 3681)
192 clutches and power-stop control
Clutches
Operators
C192S03000R, C192S056320, C192S056420, C192S069800, C192S11400R
Reexamination Certificate
active
06241067
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a clutch with two elements which, for the purpose of positively engaging one another, are provided with opposed end toothings adapted to one another, the first element being rotatably mounted and axially supported, and the second element also being rotatably mounted and axially supported, with a blocking device for selectively blocking the axial movement of the second element. The second element can be axially blocked in a first position for the purpose of being non-rotatably engaged with the first element, and can be axially moved into a second position for the purpose of being separated from the first element and freely rotatable, depending upon the blocking device being actuated or non-actuated.
It is the object of the present invention to provide such a clutch having a simple design and particularly suitable for use in the driveline of a multi-axis motor vehicle which can optionally be operated by one driven axle or two driven axles, the clutch serving to connect or disconnect the second axle.
SUMMARY OF THE INVENTION
The present invention is embodied in and carried out by a clutch of the aforesaid type, wherein the blocking device comprises the following parts:
a cavity system of changing cross-section and variable volume, and filled with a magneto-rheological fluid;
a displacing member which can be moved between a first position and a second position, which delimits the cavity system and which is connected to the second element; and
an electro-magnet which can magnetize at least part of the magneto-rheological fluid for shape-setting purposes.
There are many possibilities for the practical application of the applicant's clutch, the operating principle being that a displacing element in the cavity system is used as an axial locking element in that the magneto-rheological fluid delimited by the displacing member in the cavity system is magnetized and thus given a fixed shape, i.e., rigidified. A displacement of the magneto-rheological fluid by the displacing member into parts of the cavity system which have a changing cross-section is thus prevented, so that the displacing member is prevented from moving axially. In an advantageous embodiment, magnetization of the electro-magnetic fluid can be reduced to a small volume percentage which is contained in cavity regions whose cross-sections and shapes differ considerably.
In a simply-designed embodiment, the cavity system can have two cylinder chambers which are connected to one another (blocking chamber-compensating chamber) which each accommodate corresponding pistons operating in opposite directions (blocking piston—compensating piston), with the two cylinder chambers being connected to one another by connecting channels operating as valves. Now, if the electro-rheological fluid in the valve and in regions directly adjoining the valve on both sides and having a deviating cross-section is solidified by energizing the electro-magnet, this process corresponds to locking a valve in a corresponding connection, as a result of which overflowing of the liquid from the blocking chamber into the compensating chamber and vice versa is prevented, with the pistons being fixed in their respective positions. Advantageous features of this system are that it is wear-free and cheap to produce.
Furthermore, it is proposed that pre-tensioned spring means move the second element at least indirectly into the engaged first position of the clutch when the blocking device is set to be non-effective. This is advantageous if the disengaged second position is assumed only rarely. In this context, it is possible for the compensating piston to be loaded backwardly by the pre-tensioned spring means, especially by plate springs. The second element is then moved directly by the blocking piston via the displaced fluid.
In addition, it is proposed that controllable disengaging means move the second element into the disengaged second position of the clutch when the blocking device is set to be non-effective, the advantage being that, with the blocking device being set to be ineffective, the elements are precisely separated from one another. Furthermore, it has to be ensured that, before the blocking device is actuated, the temporarily-controlled disengaging means move the second element into the disengaged second position of the clutch. The precisely separated elements can thus be locked against the force of the spring means; the disengaging means, preferably an electro-magnet, can be switched off again. According to an embodiment which is advantageous in design and functioning, the end toothings have inclined flanks which, when the blocking device is set to be non-effective, push the second element away from the first element into the disengaged second position by application of torque.
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Bonck Rodney H.
Francis Carten
GKN Viscodrive GmbH
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