FR2631395A1 - HYDRAULIC CYLINDER, PARTICULARLY FOR ACTUATING A CLUTCH OF A MOTOR VEHICLE - Google Patents

Abstract

The invention relates to a master cylinder for actuating a hydraulic clutch of a motor vehicle. The cylinder housing 1 and the piston 2 of the master cylinder are made of plastic. The master cylinder is distinguished by the fact that only one guide element 3 is provided for guiding the piston 2. This guide element is sleeve-shaped and is combined with the other components to form a unit positioned at the inside the cylinder housing 1 by means of two compression springs 10, 12. The positioning is carried out at the same time as the mounting of the master cylinder on the vehicle apron. The invention makes it possible to reduce the length of the piston to the minimum possible for the injection molding technique, the stroke remaining the same.

Description

The present invention relates to a hydraulic cylinder, in particular

for actuation of a

  hydraulic clutch of a motor vehicle,

  killed from a plastic cylinder boot and

a plastic piston.

  We know a master cylinder, in particular

  link, for actuation of a hydraulic clutch

  motor vehicle, by the patent application al-

  German P 33 31 834.4, including a case of material

  re plastic and fitted with a flange housing a sliding piston inside a bore by means of an actuating rod and made watertight with respect to

  this bore by a sealing device, and com-

  taking a valve device actuated by the pis-

  ton, this valve device connecting a

  compensation to a pressure chamber by a

  pick closed by actuation of the val-

  ve in the released position of the master cylinder.

  The previously mentioned German patent application proposes to surround the surface of the shell of the shoemaker with a metal sleeve inside the seal area of the

  piston and make the metal flange, the su-

  anchor to the housing and press it, by the

  chon, against a stop on the housing.

  The object of the present invention is: To improve the known designs and to

  reduce the cost. These are, in particular,

  improve the conditions of production in great se-

  series of plastic hydraulic cylinders.

  The object of the invention is to largely avoid the

  metal posing. On the other hand, the components in ma-

  plastic should be used in larger

number than so far.

  The assembly of the interior components of the cy-

  hydraulic liner must be simplified, in particular

  bind for mass production. The invention

  should allow all components to be mounted if possible

  by inserting them from one side only inside

  laughing of the open cylinder case. The use of threaded fittings should be largely avoided. The

  assembly time must be reduced.

  The manufacture of plastic bodies

  that in the form of tubes, sleeves or cylinders

  dres requires a taper of the interior space in order to be able to perfectly remove the tool from the injection molded part. This conicity can have, in particular in the case where the overall axial lengths are large, an unfavorable effect

on the operation of the cylinder.

  In addition, the accumulation of plastic material

  that presents the risk of deformations not desired during solidification. Practice shows that

  cracks and warping can occur.

  The object of the present invention must provide

  nen a precautionary measure to exclude the adverse effects of aspects of the technique

  previously mentioned on the structure

  ture and operation of a hydraulic cylinder

than.

  In this context, one of the objects of the pre-

  sente invention is to create the necessary conditions

  res to reduce the length. the piston to the minimum possible for the injection molding technique,

the race remaining the same.

  With regard to the design known from the German patent application mentioned at the beginning, the object of the present invention must make it possible to achieve that the piston is no longer guided on

  two parts, as described by this patent application

vet, but only on a part.

  Indeed, the guidance on two parts pre-

  feels the disadvantage of not being able to guarantee a regular displacement of the piston. When the piston

  OS is guided on two parts, it appears components

  health of forces which are no longer directed along the axis of the piston. These force components create disturbances during operation and a

premature wear.

  Compared to the technique known in the form of the German patent application mentioned above, the invention aims to avoid the

  metal flange 41 and metal cup 36

  presented in this German patent application.

  In accordance with the present invention, these objects are achieved in that it is intended, for the

  guiding of the piston, in essence a guiding element

  ge made of plastic, which is positioned inside the cylinder case by at least one

compression spring.

  In another embodiment of the

  vention is provided for a unit made up of the

  guide and other components, such as

  seals and a disc comprising hydraulic channels

  preferably arranged in the radial direction,

  arranged inside the cylinder case and po-

  sitioned by at least one compression spring.

  In a compact design, the boot maker

  cylinder has a smaller radius area, zo-

  ne of the pressure chamber, inside the-

  which hydraulic pressure is established in the -

  case of the displacement in front of the piston and an area of larger radius, area of the unit, inside

  which the components of the unit, including the

  guide guides are arranged coaxially with one another

compared to others.

  The assembly is facilitated in particular in that a first compression spring is provided.

  inside the unit area and a second res-

  compression spell outside the hydraulic cylinder

  lique, and in that these two compression springs

  are configured and arranged so that they position-

bring unity.

  In a preferred embodiment, there is provided a hydraulic cylinder mounted on a motor vehicle, the assembly of which is determined by the

  following mounting procedure: first phase of installation

  stage: preload, without play, of the components of the unit including the guide element inside the cylinder case by means of the first compression spring, second phase of assembly: tightening of the components of the unit, including including guide element

  by the second compression spring and by a

  sheet metal shovel, while simultaneously mounting the cylinder

  dre hydraulic on the apron of the motor vehicle.

  In addition, a pressure reduction body is provided, with a metallic thread, fixed to the cylinder housing, in particular by the acoustic method,

  - that is to say by ultrasonic radiation.

  A particularly simple assembly of the master-

  cylinder is permitted due to the fact that a

  shovel which is configured as a valve cup and which fulfills the function of non-return valve

relative to the tank.

  In order to easily fix the piston rod inside the piston, it is planned to arrange it inside the piston where it is held by a

rubber element.

  The different objects and characteristics of

  the invention will now be detailed in the description

  description which follows, made by way of nonlimiting example, with reference to the appended figure which represents:

  A hydraulic cylinder in axial section.

  The cylinder housing 1 and the piston 2 are made of plastic. A sleeve-shaped guide element 3 for guiding the piston is arranged inside the case. This element of

  guide is also made of plastic. The box

  cylinder tier has a smaller radius area and a larger radius area. The area of smaller radius essentially forms through the pressure chamber 4. The pressure builds up inside the chamber 4 when the piston 2 moves to the left. Hydraulic fluid is transmitted through the

connection 5 to the slave cylinder.

  Inside the cy-

  liner of larger radius is housed a unit of

different components.

  This unit includes the following components

  vantes, arranged coaxially with respect to

  others: a valve cup 6, a disc shaped

  ring and corrugated core 7 provided with channels 8 arranged in the radial direction, a seal 9, and a guide element 3. The components of the unit are subjected to the pressure exerted by the compression spring 10

  which is also arranged coaxially and which trans-

  brings its strength to unity by a profiled ring 11.

  A second compression spring is located

  outside the cylinder and identified by the number

  reference fre 12. The compression spring 12 exerts a force on the sheet metal cup 13 which acts, for its part, through the shoulder 14 of the guide element 3, on the components of the unit. The unit is therefore maintained as a whole by the two

compression springs 10, 12.

  The assembly of the maltre-cylinder on the vghi-

  cule automobile is as follows.

  First, the components of the unit, including the guide element, are prestressed, without play, inside the cylinder housing by means of the first compression spring 10. Then, the components of the unit, including the guide element, are tightened on the one hand by means of the spring 12 and the cup in t6le 13, while mounting

  simultaneously, on the other hand, the hydraulic cylinder

  on the apron of the motor vehicle.

  The operating mode of the master cylinder

  dre is as follows: When the foot exerts a force on the

  rod 15, the piston 2 moves to the left.

  Before this shift to the left, the hy-

  hydraulics is passed from the reservoir not shown in the figure, by the hydraulic fluid connection 16, the line 21 and, by the radial channels 8 provided inside the corrugated disc 7, by the slots 17 of the piston inside the room of

pressure 4.

  If the piston moves to the left, its left edge 18 moves beyond the channels 8 arranged in the radial direction inside the corrugated disc 7. Under the effect of the pressure established inside the room 4, lips

  of the cup 6 are in tight contact

che with the piston body.

  Thus, the cup 6 has a valve function. It closes the connection between the tank and the pressure chamber 4 at the start of the elevation of

pressure.

  When the piston 2 continues to move to the left, the pressure rises inside the pressure chamber 4. The hydraulic fluid is

  transmitted, by link 5, to the receiver, for example-

  ple to a slave cylinder. The link 5 is formed by a link body or a reduction body of

  pressure 20. This body 20 is provided with a metal thread.

  for the hydraulic line to be connected. This body 20 is fixed to the cylinder case of plastic material by the acoustic method, that is to say by ultrasonic radiation. Piston rod

  is held inside the piston by an element

rubber 19.

Claims (8)

  1. Hydraulic cylinder, in particular master cylinder for the actuation of a hydraulic clutch of a motor vehicle, composed of a plastic cylinder block and a plastic piston, characterized in that it is provided , for guiding the piston, essentially a guide element made of plastic,   which is positioned inside the cy-   line with at least one compression spring.   2. Hydraulic cylinder according to the claim   tion 1, characterized in that a unit constituted by the guide element (3) and other components,   such as seals (6, 9) and a disc (7) comprising   ning hydraulic channels (8) preferably arranged   in the radial direction, is arranged inside the cylinder housing (1) and is positioned by   at least one compression spring (10).   3. Hydraulic cylinder according to which one   conch of claims 1 or 2, characterized in   that the cylinder housing (1) has a zone of smaller radius, zone of the pressure chamber, inside which a hydraulic pressure is established in the case of the displacement in front of the piston (2) and a zone of larger radius, area of the unit, within which the components   (6, 7, 9) of the unit, including the guide element   ge (3) are arranged coaxially with respect to each other to others.   4. Hydraulic cylinder according to which one   conch or more of the preceding claims,   characterized in that a first spring is provided   compression (10) inside the area of the u   nity and a second compression spring (12) outside the hydraulic cylinder, and in that these two compression springs are configured and   arranged so that they position the unit.   5. Hydraulic cylinder according to one   conch or more of the preceding claims,   when mounted on a motor vehicle,   laughed at in that its assembly is deter-   undermined by the following mounting procedure: first   assembly phase: prestressing, without play, of the   components (6, 7, 9) of the unit including the guide element (3) inside the cylinder housing (1)   by means of the first compression spring (10),   second assembly phase: tightening of the components (6, 7, 9) of the unit, including the guide element (3) by the second compression spring (12) and by a sheet metal cup (13), all by simultaneously mounting the hydraulic cylinder on the bulkhead of the motor vehicle.   6. Hydraulic cylinder according to which one   conch or more of the preceding claims,   characterized in that a connecting body (20) has   the metallic let is fixed to the cylinder case (1),   in particular by the acoustic method, that is to say say by ultrasonic radiation.   7. Hydraulic cylinder according to which one   conch or more of the preceding claims,   characterized in that a cup (6) is provided which is configured as a valve cup and which fulfills the function of non-return valve by compared to the tank.   8. Hydraulic cylinder according to which one   conch or more of the foregoing claims,   characterized in that the piston rod (15) is   arranged inside the piston where it is now   bare by a rubber element (19).