DE112013004551B4 - Rotating cover-tight slave cylinder - Google Patents

Abstract

Rotating cover-tight slave cylinder (1) of a release device for the actuation of a clutch of a motor vehicle with a stationary hydraulic feed / stator (2) of a hydraulic medium to a pressure chamber (3) of the rotating slave cylinder (rotor) (1), in which one is operatively connected to the clutch stationary disengaging piston (4) can be moved axially along an axis of rotation (A) by pressurizing the hydraulic medium, the disengaging piston actuating a plate spring of the clutch and a compensation device integrated in the rotating slave cylinder (1), which centrifugal forces acting on the disengaging piston (4) acting hydraulic medium and thus prevents an undesired disengagement of the disengaging piston (4), characterized in that the compensation device has one or more centrifugal masses (5) which can be brought into operative connection with the disengaging piston (4) and act on the latter with a speed-dependent counterforce n that the centrifugal masses (5) are accommodated in a radially freely movable manner and cause an axial counterforce on the disengaging piston (4) of the slave cylinder (1) via a ramp (5.1) and that the hydraulic medium in the pressure chamber (3) of the slave cylinder (1) Acting pressure with an axial force F acts on the surface of the release piston and via the ramp (5.1) of the centrifugal mass (5) the force (F) of the centrifugal mass (5) upon contact with the slope (4.1) of the release piston (4) into a radial one and disassembling an axial component, the axial component counteracting the force (F).

Description

The invention relates to a rotating cover-fixed slave cylinder according to the preamble of the first claim.

In hydraulically actuated disengaging devices, axial vibrations from the crankshaft, which are transmitted to the disengaging device, can lead to pressure fluctuations in the fluid system. In order to avoid this, concepts have been developed which provide for assembly / integration of the release device on the clutch cover (cover-releaser). For example, in the case of a clutch release mechanism, the concentric slave cylinder and the clutch cover are combined to form a functional unit with an internally closed power flow. The connection to the clutch cover is usually made via a roller bearing (cover bearing), which is provided in addition to a release bearing. As a result, the slave cylinder does not rotate with the clutch cover.

However, here too, the vibrations originating from the crankshaft can be transmitted to the clutch and thus to the release bearing, for example, which rests on a plate spring, and thus also to the slave cylinder. In addition, the rolling bearings used represent a high cost factor and take up a considerable amount of space.

For this reason, other known solutions provide cover-fixed disengagement devices that do not use both a cover bearing and a disengagement bearing. In these disengaging devices, the concentric slave cylinder is fastened to the clutch cover of the clutch in such a way that it rotates with it. However, this means that to realize the supply of pressure fluid from a stationary fluid supply device (also referred to as a stator) to the rotating slave cylinder (also referred to as a rotor), a rotary feedthrough must be provided. What is important here is a corresponding radial and axial mounting of the stator on the rotor with a functional design of the bearing points in order to ensure safe operating behavior for the seals and thus for the overall system, as well as the use of appropriate seals for the rotating union.

Because the hydraulic supply is at a standstill, the hydraulic medium is fed into the rotating releaser via the rotating union. If the pressure is sufficiently high, the release piston is moved in the axial direction against the plate spring tongues of the plate spring of the clutch.

Since the pressure in the system is the same everywhere, this also affects the seals of the rotating union. The release systems are designed as standard with pressures of up to 40 bar. These high pressures in connection with the high sliding speeds require structurally very complex seals, which has a negative effect on the costs and the space required.

A pressure transmission integrated into the hydraulic path between the master cylinder and slave cylinder, by means of which the pressure of the master cylinder is reduced from 40 bar to 5 bar, for example, ensures that when the hydraulic supply is at a standstill, the hydraulic medium is conducted at a reduced pressure into the rotating clutch release via the rotating union, whereby inexpensive seals can be used for the rotating union.

If the pressure is sufficiently high, the release piston is moved in the axial direction against the plate spring tongues of the clutch. This requires a larger hydraulically effective area of the release piston. Since the slave cylinder also rotates, the hydraulic medium is also set into a rotating movement and the centrifugal force acting on the hydraulic medium increases the pressure with increasing diameter or radius as a function of the speed. There is therefore a risk that the release piston will disengage in the direction of the release bearing without actuating the clutch pedal.

From the DE 38 27 946 A1 a hydraulically operated release device according to the preamble of claim 1 is known. Another state of the art is in KR 10-2008-0095979 A as well as in the JP H02-017226 A described.

The object of the invention is to develop a cover-tight slave cylinder with which an unwanted disengagement of the disengaging piston is prevented even at high speeds.

This object is achieved with the characterizing features of the first claim.

Advantageous refinements result from the subclaims.

The rotating cover-fixed slave cylinder of a disengaging device for actuating a clutch of a motor vehicle has a stationary hydraulic supply / stator of a hydraulic medium to a pressure chamber of the rotating slave cylinder (rotor) in which a disengaging piston that is operatively connected to the clutch along the axis of rotation ( A ) can be moved axially by pressurization of the hydraulic medium, a compensation device being integrated in the rotating slave cylinder according to the invention, which centrifugal forces of the piston Hydraulic medium compensated and thus prevents an undesired disengagement of the piston.

This is particularly intended for applications such as a pressure intensifier arranged between the master cylinder and slave cylinder that measures the pressure of e.g. 40 bar on the master cylinder side reduced to 5 bar on the slave cylinder side, which inevitably means that the hydraulically acting surface has to be enlarged and thus an undesired disengagement of the release piston when the clutch pedal is not actuated must be prevented.

For this purpose, the compensation device has one or more centrifugal masses which can be brought into operative connection with the disengaging piston and act on the latter with a speed-dependent counterforce.

The centrifugal masses are accommodated in a radially free manner and each cause an axial counterforce on the disengaging piston of the slave cylinder via a ramp. For this purpose, the centrifugal masses are accommodated in a centrifugal mass holder so that they can move freely and radially.

The centrifugal mass holder is advantageously fastened to the rotor by means of snap hooks, the centrifugal masses being axially fixed uniformly over the circumference in T-shaped guide rails and arranged to be radially displaceable.

Cut-outs are provided in the centrifugal mass holder through which the release piston, which acts against the diaphragm spring of the clutch, engages. In order to ensure a uniform contact pressure on the plate spring tongues despite the cutouts, a pressure plate is attached to the release piston, which act on the plate spring of the clutch in the axial direction.

The pressure caused by the hydraulic medium in the pressure chamber of the slave cylinder acts with an axial force F _FL the force of the centrifugal mass is applied to the surface of the release piston and through the ramp of the centrifugal masses F _FM upon contact with the ramp of the release piston broken down into a radial and an axial component, the axial component of the force F _FL counteracts, so that the release piston does not perform an undesired release movement.

If the clutch pedal is now actuated, an additional release force acts due to the pressure provided by the pressure intensifier F _A in the axial direction, whereby the release piston moves in the axial direction against the plate spring of the clutch and at the same time presses the centrifugal masses radially inwards towards the center of rotation of the slave cylinder via the ramps.

The invention is explained in more detail below on the basis of exemplary embodiments and associated drawings.

• 1 einen Längsschnitt durch einen rotierenden deckelfesten Nehmerzylinder,
• 2 die Prinzipdarstellung eine Fliehmassenhalterung mit Fliehmassen.
• 3 eine dreidimensionale Darstellung der am Rotor befestigten Fliehmassenhalterung mit den Fliehmassen und eine Druckplatte, die am Ausrückkolben mittels Schnapphaken befestigbar ist.

Show it:

• 1 a longitudinal section through a rotating cover-fixed slave cylinder,
• 2 the basic representation of a centrifugal mass holder with centrifugal masses.
• 3 a three-dimensional representation of the centrifugal mass holder attached to the rotor with the centrifugal masses and a pressure plate which can be attached to the release piston by means of snap hooks.

The rotating cover-tight slave cylinder 1 (Rotor) of a disengagement device for actuating a clutch, not shown, of a motor vehicle has according to 1 a stationary hydraulic supply (stator) 2 a hydraulic medium to a pressure chamber 3 of the rotating slave cylinder (rotor) 1 in which a release piston 4 along the axis of rotation A is axially movable by pressurizing the hydraulic medium.

In the rotating slave cylinder 1 are centrifugal masses 5 radially freely movable but axially fixed to a centrifugal mass holder 6 added. The centrifugal masses 5 point towards the release piston 4 ramps 5.1 on that in the form of bevels with an angle α are inclined radially outwards. The release piston 4 has a corresponding sloping surface 4.1 on. On the release piston 4 is a pressure plate in the direction of the plate spring of the clutch, not shown here 7 attached, which acts on a plate spring of the clutch (not shown) in the axial direction. To do this, the release piston engages 4 in some areas through recesses (not visible here) of the centrifugal mass holder 6 ,

Between the slave cylinder 1 and the hydraulic supply 2 is a rotating union 8th provided for the hydraulic medium. With the hydraulic supply at a standstill 2 and the rotating union 8th the hydraulic medium is fed into the rotating slave cylinder.

By means of a pressure intensifier indicated schematically and in a reduced manner above the hydraulic supply 10 one in a case 11 axially displaceable piston 12 with different pressure areas in the direction of the master cylinder side and the slave cylinder side, the pressure provided by the master cylinder (not shown) when the clutch pedal is actuated is reduced from approximately 40 bar to 5 bar and then fed to the slave cylinder. Due to the reduced operating pressure of the hydraulic medium, inexpensive conventional seals can now be used D can be used for the rotating union.

With the help of the centrifugal masses that move freely in the radial direction 5 will over their ramps 5.1 if this on the corresponding sloping surface 4.1 of the release piston 4 with a suitable centrifugal force come to rest on the release piston 4 generates a speed-dependent counterforce, which prevents the release piston from disengaging 4 prevented when the clutch pedal is not actuated.

In 2 is the centrifugal mass holder 6 shown, which has snap hooks 6.1 can be attached to the rotor. On the centrifugal mass holder 6 are the centrifugal masses 5 , These are evenly distributed over the circumference and are axail via T-shaped guide rails 6.2 held on the bracket and only allow movement in the radial direction. The centrifugal mass holder 6 includes clippings 6.3 , so that the release piston (not shown here) can actuate the diaphragm spring unhindered.

To actuate the disc spring, not shown, over the entire circumference, on the release piston 4 a printing plate 7 with the help of snap hooks 7.1 attached what from the representation in 3 can be seen. The release piston 4 through the cutouts 6.3 the centrifugal mass holder 6 reaches, points to the floppy hooks 7.1 corresponding recesses 4.2 on. The centrifugal masses 5 are, as indicated by the arrows, mounted radially outwards on the centrifugal mass holder.

Catches the clutch and thus the slave cylinder 1 to turn the centrifugal masses move 5 radially outwards. The influence of the rotary movement on the hydraulic medium, on the other hand, acts with a delay. Due to the friction between the walls of the slave cylinder 1 and the outer regions of the hydraulic medium are only gradually rotated. The outer areas then cause the inner areas to rotate with the inner friction of the hydraulic medium. This effect ensures that a counterforce can only be generated before the release piston unintentionally disengages.

After a certain time, the complete hydraulic medium turns with it. Due to the centrifugal force acting on the hydraulic medium, the pressure increases exponentially with the diameter. This pressure acts on the surface of the release piston 4 and has an axial force F _FL resulting in the release piston 4 moved to disengage (see 1 ). Through the ramp 5.1 the centrifugal masses 5 becomes the force F _FM the centrifugal mass 5 when contacting the ramp-like slope 4.1 of the release piston 4 broken down into a radial and axial component. The axial component acts on the force F _FL against the piston in the disengaging direction when the clutch pedal is not actuated and prevents the piston from disengaging unintentionally 4 ,

If you now operate the clutch pedal, not shown, the balance of forces is released in favor of the disengagement process and it also acts accordingly 1 the release force F _A in the axial direction. This causes the release piston to move 4 in the axial direction against the disc spring, not shown, of the clutch and at the same time presses the centrifugal masses 5 radially inwards towards the center of rotation of the slave cylinder 1 ,

LIST OF REFERENCE NUMBERS

1

slave cylinder

2

stationary hydraulic supply

3

pressure chamber

4

release piston

4.1

sloping surface

4.2

recesses

5

centrifugal masses

5.1

ramps

6

Fliehmassenhalterung

6.1

snap hooks

6.2

guide rails

6.3

cutouts

7

printing plate

7.1

snap hooks

8th

Rotary union

10

Pressure booster

11

casing

12

piston

A

axis of rotation

D

seals

F _A

disengaging

F _FM

Force of the centrifugal mass 5

F _FL

Power of the piston 4 in the disengaging direction when the clutch pedal is not actuated

α

angle

Claims (7)

Rotating cover-tight slave cylinder (1) of a release device for actuating a Coupling of a motor vehicle with a stationary hydraulic supply / stator (2) of a hydraulic medium to a pressure chamber (3) of the rotating slave cylinder (rotor) (1), in which a disengaging piston (4), which is operatively connected to the clutch, passes along an axis of rotation (A) Pressurization of the hydraulic medium can be moved axially, the disengaging piston actuating a plate spring of the clutch and a compensation device being integrated in the rotating slave cylinder (1), which compensates centrifugal forces of the hydraulic medium acting on the disengaging piston (4) and thus an undesired disengaging movement of the disengaging piston (4 ), characterized in that the compensation device has one or more centrifugal masses (5) which can be brought into operative connection with the disengaging piston (4) and act on the latter with a speed-dependent counterforce, that the centrifugal masses (5) are accommodated in a radially free manner and via a ramp (5.1) e cause an axial counterforce on the release piston (4) of the slave cylinder (1) and that the pressure acting through the hydraulic medium in the pressure chamber (3) of the slave cylinder (1) acts with an axial force F _FL on the surface of the release piston and via the ramp ( 5.1) the centrifugal mass (5), the force (F _FM ) of the centrifugal mass (5) upon contact with the slope (4.1) of the release piston (4) is broken down into a radial and an axial component, the axial component of the force (F _FL ) counteracts. Slave cylinder after Claim 1 , characterized in that the centrifugal masses (5) are accommodated in a centrifugal mass holder (6) so as to be freely movable in a radial direction. Slave cylinder after Claim 2 , characterized in that the centrifugal mass holder (6) is attached to the slave cylinder (1) by means of snap hooks (6.1). Slave cylinder after Claim 2 or 3 , characterized in that the centrifugal masses (5) are axially fixed uniformly over the circumference in T-shaped guide rails (6.2) and arranged to be radially displaceable. Slave cylinder according to one of the Claims 1 to 4 , characterized in that the centrifugal mass holder (6) has cutouts (6.3) through which the release piston (4) extends. Slave cylinder according to one of the Claims 1 to 5 , characterized in that on the disengaging piston (4) a pressure plate (7) is fixed, which acts on a plate spring of the clutch in the axial direction. Slave cylinder according to one of the Claims 1 to 6 , characterized in that when a clutch pedal is actuated, an additional disengagement force (F _A ) acts in the axial direction and that the disengagement piston (4) moves in the axial direction against the plate spring of the clutch and at the same time the centrifugal masses (5) via the ramps (5.1 ) pushes radially inwards in the direction of the axis of rotation (A) of the slave cylinder (1).

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