WO1992004557A1

WO1992004557A1 - Clamping element

Info

Publication number: WO1992004557A1
Application number: PCT/EP1991/001643
Authority: WO
Inventors: Peter Amborn; Klaus Greulich; Herbert Frielingsdorf; Joachim Altdorf; Wolfgang Hildebrandt
Original assignee: Peter Amborn; Klaus Greulich
Priority date: 1990-08-30
Filing date: 1991-08-30
Publication date: 1992-03-19
Also published as: DE4027369A1

Abstract

A rotary drive operated clamping or spreading element, for example for operating a friction brake in a locking differential, has a housing (1) with an essentially rotationally symmetrical periphery, at least one excentrically arranged plunger (8) that is excentrically arranged in the housing (1) and is movable in a parallel direction to its axis, a piston (5) movable in relation to the housing (1) or a jaw spreadable in relation thereto, a pressure chamber (13) delimitated by the housing (1) and piston or jaw and upon which the plunger (8) acts at least indirectly, and a cam plate (2) coaxially arranged in relation to the housing (1), that can be driven in relation thereto and that is provided with a frontal curved face that acts on the plunger (8).

Description

Clamping element

description

The invention relates to a clamping or expanding element which can be actuated by a rotary drive and which can generate axial adjusting forces, and possibly also radial adjusting forces. In both cases, it is suitable, for example, for actuating a friction brake in a limited slip differential. It can also be used for other applications, for example a self-regulating rotary adjustment in a camshaft drive. The relative movement of two parts to one another about an axis of rotation is required to generate the force.

In the preferred application mentioned above, one of the parts that can be rotated relative to one another can be connected in a rotationally fixed manner to the differential carrier or one of the axle shaft wheels and the other of the parts that can be rotated relative to one another with the other of the axle shaft wheels. If there is a speed difference between the axle sprockets, there is then a build-up of pressure that can be converted via a piston into an axial thrust effect on the axle sprockets to the outside or via jaws into a contact force directly acting on the axle sprockets, which in each case results in a braking effect of the axle sprockets against counter surfaces in the differential cage or can generate relative to each other. The invention has for its object to provide a clamping element which generates a pressure build-up which can be converted into spreading or actuating forces when there is a speed difference between two parts which can be rotated relative to one another. The solution consists in such a clamping element, which is characterized by a housing part with an essentially rotationally symmetrical housing, at least one plunger which can be displaced eccentrically in the housing part, at least one plunger arranged in the housing part, which is displaceable relative to this piston or which is expandable relative to this, one from the housing part and Piston or jaw limited pressure space, on which the plunger acts at least indirectly, and a cam disk arranged coaxially to the housing part and drivable relative to it, which acts on the plunger with an end-face cam surface. In the same way, a cam curve lying on a circumferential surface can also act on a radially displaceable plunger.

The clamping force generated here is pulsating with the frequency of the plunger actuation. The plunger, pressure chamber and piston or jaw act together as pressure boosters. The housing part and the cam disc can be separated from one another for assembly reasons and can only be held in contact with one another by further parts; however, it is also possible to axially secure the cam disk with respect to the housing part.

In a preferred development of the invention, a pressure medium reservoir connected to the pressure chamber via a throttle line on the one hand and a check valve open to the pressure chamber on the other hand is provided. This design can ensure that a End the relative rotational movement in a position with an inserted plunger and thus increased pressure in the pressure chamber, which can be reduced. If a relative rotation movement occurs again and the plunger kicks out, pressure medium can then be sucked into the pressure chamber in sufficient quantity again via the check valve. In a favorable embodiment, the reservoir mentioned is delimited by a piston which is spring-supported in the housing part and which supports an overflow from the pressure medium reservoir via the check valve into the pressure chamber.

The plunger preferably acts via a spring on an element delimiting the pressure chamber, in particular a corrugated pipe, in order to ensure security against excess pressure in the pressure chamber.

The piston can be guided directly coaxially in the housing part, but it is preferred to connect the two parts via a corrugated tube enclosing the pressure chamber.

A further embodiment is to provide an overflow channel controlled by the relative displacement of the piston relative to the housing part, which creates a connection from the pressure chamber to a further pressure medium reservoir. This can be used, for example, to limit the axial advance of the piston. However, it is preferred to design the overflow channel in such a way that the pressure chamber is relieved when the piston is externally adjusted. This can be the case in particular when used in a differential gear with helical gear wheels, the braking effect achieved by the tensioning element being reversed when the thrust is reversed, to ensure compatibility of the differential gear with an anti-lock braking system.

An exemplary embodiment of the invention is described in the figure below. For this purpose, the housing part 1 is shown, in which a longitudinal groove 12 is provided for securing against rotation with respect to the differential carrier (not shown in more detail). The housing part 1 of the tensioning element is connected in a rotationally fixed manner to an axial piston 5 via a corrugated tube 15. In an alternative embodiment, the axial piston 5 can in turn be secured against rotation in relation to the differential cage in the latter. A pressure chamber 13 is enclosed by the corrugated tube 15 between the housing 1 and the axial piston 5. The axial piston 5 is supported on one of the axle gear wheels 26. A cup-shaped cam disk 2 is connected to the other of the axle shaft gears 27 via a bracing (not shown in more detail), the cam cam end of which is indicated by a dashed line. Over the circumference, this cam disk 2 has at least one, in the illustration two front elevations and two depressions.

The cam disk 2 acts directly on a plunger 8 arranged eccentrically in the housing 1. This slides directly in a socket 7, which is inserted into the housing 1. The plunger 8 acts via a compression spring 18 on a spring holder 6 which is connected directly to a corrugated tube 16 which is closed at the end. The corrugated tube 16 connects to the socket 7. When the axle shaft wheel 27 rotates relative to the differential cage 25, the plunger 8 is moved by the cam disk 2 into an oscillating movement offset, which has the compression spring 18, which has an essentially overload function, and the corrugated tube 16 as pulsation on the pressure chamber 13.

A further bushing 9 is inserted into the housing, diametrically opposite to the plunger 8, axially parallel, in which a further piston 10 is held, which is supported on a retaining ring 23 via a compression spring 19 and a disk 11. A check valve 20 is inserted into the bushing 9, which includes a reservoir 21 with the piston 10, the check valve opening from the reservoir 21 to the pressure chamber 13. A throttle channel 22 leads from the pressure chamber 13 along the valve body of the valve 20 and radially through the bushing 9. If the cam disk 2 comes to a standstill when the plunger 8 is pressed in and the pressure in the pressure chamber 13 is increased compared to the housing 1, the increased pressure builds up would mean an increased blocking effect, via the throttle duct 22. Upon subsequent renewed rotation of the cam disk 2 relative to the housing 1, the piston 10 pushed back against the force of the compression spring 19 when the pressure is equalized will open the check valve 20 and push the plunger 8 into a position partially pushed out of the housing 1 via the pressure chamber 13 and the corrugated tube 16 . The next time the plunger 8 is pressed in, a high pressure again arises in the pressure chamber 13, since the check valve 20 closes immediately.

A bolt 3 is clamped in the housing 1 by means of a nut 24, on which the axial piston 5 can be displaced. Furthermore, a disk body 4 is pressed onto this bolt 3 and is connected to the axial piston 5 via a further corrugated tube 14. In the bolt 3 is a Overflow channel 29 is provided, which releases the pressure chamber 13 with the contents of a relief reservoir 28 enclosed by the corrugated tube 14 between the disk 4 and the axial piston 5 when the axial piston 5 moves axially toward the housing 1. Such a displacement of the axial piston 5 inwards in the differential cage 25 can take place with helical gearwheels 26, 27 when reversing thrust, so that in this situation, even when cornering or wheel slip, ie speed difference between the axle gears, no braking effect can occur. However, the tensioning element according to the invention is also functional without the pressure relief chamber 28 formed from corrugated tube 14, disk 4 and axial piston 5 and which can be acted upon via the overflow duct 29. The axial piston 5 can be closed in the form of a disk without these parts for better sealing.

Reference list

1 housing part

2 cam disc

3 bolts

4 disc

5 axial pistons

6 pen holders

7 socket

8 plungers

9 socket

10 pistons

11 disc

12 longitudinal groove

13 pressure chamber

14 corrugated pipe

15 corrugated pipe

16 corrugated pipe

17 compression spring

18 compression spring

19 compression spring

20 check valve 21 pressure medium reservoir 22 throttle channel

23 circlip

24 mother

25 differential cage 26 axle shaft gear

27 axle shaft gear

28 Relief reservoir 29 Overflow channel

Claims

1. Rotatable drive actuated tensioning or expanding element, for example for actuating a friction brake in a limited slip differential, characterized by a housing part (1) with a substantially rotationally symmetrical housing circumference, at least one eccentrically displaceable plunger (8) arranged in the housing part (1), at least one arranged in the housing part (1), with respect to this displaceable piston (5) or with this expandable jaws, a pressure chamber (13) limited by the housing part (1) and piston or jaws, on which the plunger (8) acts at least indirectly, and one Cam disc (2) which is arranged coaxially to the housing part (1) and can be driven relative to the latter and which acts on the plunger (8) with an end-side cam surface.

2nd Clamping element according to claim 1, characterized by a first pressure medium reservoir (21) connected to the pressure chamber (13) via a throttle line (22) on the one hand and a check valve (20) opening towards the pressure chamber (13) on the other hand.

3. Clamping element according to claims 1 to 2, characterized by a second pressure medium reservoir (28) connected to the pressure chamber (13) by means of an overflow channel (20) controlled by the piston (5) or the jaws.

4. Clamping element according to claims 1 to 3, characterized in that the plunger (8) acts via a spring (18) on an elastic element which acts on the pressure chamber (13), in particular a corrugated tube (16).

5. Clamping element according to claims 1 to 4, characterized in that the first pressure medium reservoir (21) by a resiliently supported on the housing part (1) piston (10) is limited.

6. Clamping element according to claims 1 to 5, characterized in that a corrugated tube (15), which is connected to the housing part (1) and piston (5), limits the pressure space (13) on the circumference.

7. Clamping element according to claims 1 to 6, characterized in that the second pressure medium reservoir (21) by a between a disc (4) and the piston (5) fixed corrugated tube (14) is limited.