DE10352941A1 - Pressure cylinder for hydraulic actuator, has piston sleeve enclosing dampening unit and moving axially against seating part formed against piston rod so that unit absorbs pressure pulsations introduced via pressure chamber - Google Patents

Abstract

The cylinder has an inner cylinder (42) with a hydraulic pressure chamber (28) into which a piston (22a) moves. The piston has a sleeve that encloses a dampening unit (52a) made of elastomer. The dampening unit rests on an insert (54). The sleeve moves axially against a seating part (56) formed against a piston rod and connected to the insert so that the dampening unit absorbs pressure pulsations introduced via the chamber.

Description

The The invention relates to a pressure medium cylinder for a hydraulic actuator to operate a vehicle clutch.

hydraulic Clutch actuation systems on Vehicles have the unwanted Feature on that of the internal combustion engine of the vehicle triggered Axial vibrations over the Friction clutch and its diaphragm spring on the clutch release bearing and transmit the associated disengagement devices become. These axial vibrations settle in a hydraulic pressure chamber, the one by a donor and a slave cylinder with an in between arranged hydraulic line is limited, and can be a unpleasant tingling in the foot of a Driver at the touch of the clutch pedal.

On the one hand, the pressure pulsations can already be damped by the use of an elastic pressure line, for example a steel-rubber composite, which is elastic in limits. In applications where this measure alone is insufficient, additional, designed as so-called Kribbelfilter attenuators can be integrated in the hydraulic actuation system. However, these entail an increased cost and an additional space requirement. For example, the DE 100 49 220 A1 an attenuator disposed in a hydraulic pressure line for a clutch actuation system and comprising a cylindrical housing having diaphragms arranged on the front side and capable of oscillating during pressure pulsations of the hydraulic fluid. Thus, in the event of a sudden increase in pressure as a result of the bulging of the membranes, an additional volume can temporarily set in and thus the pressure pulsation can be alleviated.

Steel-rubber lines are increasingly being made easier to produce and cheaper, completely replaced a plastic manufactured pressure lines, which at a Compressive load due to a clutch actuation one compared to the aforementioned conductivity type lower elasticity and thus a lower Have volume. When replacing or replacing but not only the pressure lines, but also the same replaced pressure medium cylinder replaced or replaced. As with the hydraulic actuation system co-operating arrangement of clutch, clutch release and clutch pedal Fixed in the vehicle, on the one hand changes the damping behavior and on the other hand, the separation and the Einkuppelpunkt the clutch, what for the driver by a changed Foot and foot Beinhaltung makes noticeable, due to the acting leg lever ratios to Part of a greater effort and at least getting used to it require.

The The object of the invention is starting from it, a device for effective damping of pressure pulsations in a hydraulic clutch actuator to create which, without adaptation of the cooperating with this, in the vehicle permanently installed mechanical coupling organs, carried out can.

The Invention solves the task with a pressure cylinder, in the piston a Dämpfungslement according to the claim 1 is arranged.

By the integration of the damping element unnecessary in a pressure cylinder additional Measures in the form of a separate, within the hydraulic Actuator, to be arranged Attenuator. The damping element can over the selection of its shape and hardness targeted to a desired operating characteristic which makes it both soft and hard can be adjusted. The arrangement outside the pressure chamber allowed doing a big one Variety in its material selection. On a resistance of the attenuator across from the hydraulic fluid needs now no consideration.

According to claim 2 is the damping element advantageously designed as an elastomeric part.

In An embodiment of the invention according to claim 3 comprises the damping element a frictionally engaged arranged to the wall area and / or the receiving arrangement Feather.

The Invention will become apparent from the following description and the figures exemplified. Show it:

1 a schematic representation of a hydraulic actuator for a motor vehicle clutch,

2 a schematic representation of a pressure medium cylinder with an elastomeric part arranged in a jacketed piston as a damping element,

3 a piston with a frictionally arranged on this plate spring as a damping element,

4 an arrangement of a damping element in a mantelless executed piston.

According to 1 is schematically a hy draulic actuating device 10 for actuating a motor vehicle clutch 12 shown which on a chassis 14 a motor vehicle is arranged and wherein a master cylinder 16 with a piston 18 and a slave cylinder 20 with a piston 22 are arranged, with each other via plug-in couplings 24 with one with a fluid 25 filled hydraulic line 26 are connected and a common pressure room 28 form. The piston 18 of the master cylinder 16 can by a pedal 30 be pressed, whereupon the Kol ben 22 the slave cylinder 20 shifts and a clutch fork 32 for disengaging the clutch 12 on one as an internal combustion engine 34 trained drive unit controls. The coupling 12 is the input side with the output shaft of the engine 34 and output side with a manual transmission 36 connected.

2 shows a trained as a slave cylinder pressure cylinder 20a which essentially consists of a two-part plastic housing with an outer one 38 and an inner housing part arranged therein by means of a latching connection 40 exists, which both have a common inner cylinder 42 for receiving an axially slidable piston 22a provide. The piston 22a has a trained as a deep-drawn, one-sided with a bottom 44 executed metallic piston skirt sleeve 46 on that a wall area 48 of the piston 22a forms. This wall area 48 and the inner cylinder 42 define a variable with the hydraulic fluid 25 filled pressure room 28 , which is opposite the moving piston 22a with a ring lip seal 50 sealed against the environment. Inside the piston skirt sleeve 46 is one on the piston bottom 44 applied damping element 52a made of an elastomer, which in turn on its opposite side to a plastic insert 54 comes to the plant. The insert part 54 is from the piston skirt sleeve 46 axially slidably received and can within a certain margin against the action of the damping element 52 move axially and thus the distance to the piston crown 44 shorten.

With the piston 22a is about a running as a ball socket on the insert receiving arrangement 56 pivotally a piston rod 58 with a Kugelkalot te 60 connected, the piston rod 58 at the other end according to 1 with the clutch fork 32 and further disengagement means of the clutch 12 is in active connection. The slave cylinder 20a is above a laterally projecting from this fluid connection 62 with the in 1 illustrated master cylinder 16 in fluid communication and also has a side also on the housing part 38 arranged flange 64 for receiving a bleeder valve, not shown in the drawing.

When acting on the pressure chamber 28 initiated pressure pulsation or one via the piston rod 58 initiated vibration will be with the fluid 25 in contact piston skirt sleeve 46 opposite to the piston rod 58 connected to the insert 54 trained recording arrangement 56 axially displaced, the vibrations of the elastomeric part 52 be absorbed and are damped as a result of internal friction. That means that over the fluid 25 or via the piston rod 58 introduced pulsations are effectively suppressed in the transition to the other of the two elements.

This in 2 by way of example on a slave cylinder 20a executed damping element 52 can of course also alternatively or additionally to a master cylinder 16 will be realized.

The in 3 shown pressure cylinder 20b is identical to the example just explained, but instead of the elastomer part, it has one between the insert part 54 and the piston crown 44 frictionally arranged as Dämpfungsele element 52b acting plate spring 66 on, which is compressed at a pressure pulsation and the piston head 44 and / or on the insert 54 Friction works to make their attenuation.

The in 4 only partially shown pressure cylinder 20c includes a piston 22c , which is executed in contrast to the previous embodiments without piston skirt sleeve and its body 68 from a cylindrical plastic tube with a partition 70 consists. On the piston 22c is at the to the pressure room 28 directed side an open conical recess 72 incorporated, in which a compression spring 74 is inserted, which the piston 22c biased towards an end position. The damping element 52c is here shaped as a disc-shaped elastomer part and between an inner part 76 with a recording arrangement 56c for the piston rod 58c and the partition 70 stored. To the function of the cylinder 20c Reference is made to the above statements.

10

hydraul. actuator

12

Motor vehicle clutch

14

chassis

16

Master cylinder

18

piston

20

slave cylinder

22

piston

24

plug-in coupling

25

hydraulic fluid

26

hydraulic line

28

pressure chamber

30

pedal

32

clutch fork

34

internal combustion engine

36

manual transmission

38

outer housing part

40

inner housing part

42

inner cylinder

44

ground

46

Piston shaft sleeve

48

wall region

50

Ring lip seal

52

damping element

54

insert

56

up assembly

58

piston rod

60

spherical cap

62

fluid port

64

flange

66

Belleville spring

68

body

70

partition wall

72

recess

74

compression spring

76

inner part

Claims (3)

Pressure medium cylinder for a hydraulic actuating device for actuating a clutch of a motor vehicle, comprising - a housing ( 38 . 40 ) with an inner cylinder ( 42 ), - one in the inner cylinder ( 42 ) axially displaceable piston ( 22a -C) with a wall area ( 48 ), which has a variable hydraulic pressure chamber ( 28 ) and - the piston ( 22a -C) a reception order ( 56 ) for pivotally receiving a piston rod ( 58 ), which one via the piston ( 22a C) absorb force introduced or a force on the piston ( 22a C), characterized in that in the power transmission path between the wall region ( 48 ) and the reception order ( 56 ) a damping element ( 52a C), wel ches a relative movement of the wall region ( 48 ) to the reception order ( 56 ) and dampens pressure pulsations occurring in the hydraulic actuator. Pressure medium cylinder according to claim 1, characterized in that the Dämpfungslement ( 52a , c) is designed as an elastomeric part. Pressure medium cylinder according to claim 1, characterized in that the damping element ( 52b ) a friction fit to the wall area ( 48 ) and / or the reception order ( 56 ) arranged spring ( 66 ).