FR2551506A1 - - Google Patents

Abstract

THIS MASTER CYLINDER FOR A HYDRAULIC CONTROLLED CLUTCH INCLUDES A BODY2 IN PLASTIC MATERIAL WITH A BORE7 IN WHICH A PISTON4 IS PUSHED BY A PISTON ROD39 WITH SEALING IN RELATION TO THIS BORE. A VALVE18 SYSTEM ACTIVATED BY PISTON4 CONNECTS THE WORK CHAMBER7 AT REST TO A COMPENSATION DUCT16 AND SEPARATES IT FROM DUCT16 WHEN PISTON4 IS ACTIVATED. THE EXTERNAL SURFACE52 OF BODY2 IS FIRMLY HELD BY A POT-SHAPED SLEEVE36 AT THE PISTON GASKET31 AND THE FIXING FLANGE41 IS MADE OF METAL AND IS PLACED ON BODY2 AGAINST WHICH IT IS LOCKED BY THE SOCKET36.

Description

The present invention relates to a maler-cylinder, particularly for

  the hydraulic actuation of the clutch of a motor vehicle, comprising a body made of plastic material and provided with a flange, a piston movable in a bore by a control rod and sealingly associated with this bore and a valve system operable by the piston and connecting a compensation chamber to a pressure chamber, when the master cylinder is in position

  at rest, by a channel which can be closed when the valve system is actuated.

  A master cylinder of this type is described in British Patent Application 2,076,095. In order to avoid wear, expansion of the body and sealing defects during the operation of the master cylinder at the plastic body. and piston seals, a metal tube was inserted into the bore Such a

  The design requires a comparatively high accuracy of the dimensions of the parts involved, increases the assembly work and results in a comparatively complicated and expensive construction.

  A second metal tube surrounding said first metal tube at its protruding end of the body serves for axial attachment of the push rod, gasket and tube inserted into the body bore. The second tube, with its radially widening portion. outwardly, applies to the body flange and thus, when the master cylinder is mounted, is rigidly attached to the flange and to the integral wall of the vehicle, which is not shown in FIG. figure, by the fixing screws The second tube is a

  piece of metal sheet cut and shaped and it helps to simplify the master cylinder.

  The object of the present invention is to provide a master cylinder made of plastics material such that leaks can not occur even in the presence of high pressures. In addition, the master cylinder must allow for simple construction and easy mounting on the wall of the cylinder. fixing, actuating forces

  applied from the outside to the master cylinder to be transferred without damage to the body.

  This object is realized according to the present invention in that the peripheral surface of the body is securely surrounded by a metal sleeve at the piston seal and that the flange is made of metal, placed on the body and pushed by the sleeve against A thrust on the body When high pressures occur in the pressure chamber, the construction of the invention prevents inadmissible radial expansion of the plastic body at the piston seal, so that the piston seal fixed in the body still reliably applies to the piston, so that there can be no leakage As the forces acting on the flange during the operation of the may10-cylinder can be comparatively large, the invention provides to obtain a durable master cylinder that the flange is made of metal and is held on the body by positive engagement The flange, which consists of a piece of sheet metal The flange and the sleeve can, however, also be manufactured by pressure molding and sintering, or the like.

  by machining with removal of material.

  A method of attaching the flange to the body of the cylinder particularly easy and simple is obtained by substantially giving the flange a pot shape and mounting it on the body by a bayonet type engagement, the radially inner end. with the flange being clamped between the detents of the bayonet mount while the bottom of the bushing prevents the valve system and the piston seal 25 from escaping. In this arrangement, the bushing serves not only as a reinforcing element and fixing, but also constitutes the master cylinder cover The simple fixing of the

  Sheet metal flange provides a secure and rigid connection.

  To prevent the malter cylinder mounting position from changing during operation, it is advantageous that the flange is adapted to be locked to the body by means of a mechanism preventing torsion. consisting of a recess of the body in which engages a protrusion

of the bridle.

  Another advantage of the invention lies in the fact that the spring is located outside the body and that it rests one side on the body and the other door on a piston stop washer coming out of the body. Due to this arrangement, the overall axial length of the master cylinder body is reduced since, in a plunger construction where the piston seal is fixed on

255 1 506

  the body and forms the sliding surface and sealing of the piston, it is possible to remove the spring from the bore of the body so, according to the invention, that it surrounds the piston outside

from the body.

  To allow the use of the maltre-cylinder of the invention in various vehicles often having different clutch actuation strokes, it is favorable, to limit the stroke, that a cap can be attached to the end However, it is also possible to use a protruding bush inside the working chamber instead of this plug. When the spring is disposed inside the body, said sleeve can provide at the same time the guide of the spring.

  The various objects and features of the invention will now be detailed in the description which follows,

  By way of nonlimiting example, with reference to the appended figures, which represent FIG. 1, a longitudinal cross-sectional view of the malter cylinder according to the invention, FIG. 2 is a fragmentary sectional view of another embodiment of FIG. a master cylinder in the zone for fastening the flange FIG. 3, a plan view of the master cylinder of FIG. 2 in the direction of arrow X, and FIG. 4, a partial longitudinal sectional view of FIG. another embodiment in the area of the closed end of the bore

of the master cylinder.

  FIG. 1 shows a master cylinder 1 composed of a body 2 made of plastics material and comprising a bore 3 extending in the longitudinal direction of the body 2 and where is guided a piston 4 made of plastics material that can move axially ,

  which piston 4 leaves the open end 5 of the maltre-cylinder 1.

  The piston 4 has a blind bore 6 for receiving an actuating rod, not shown in the figure, which can be moved by a clutch pedal of the vehicle. In connection with the piston 4 and the body 2, said bore 3 forms a working chamber 7 which comprises at its closed end 8 a pressure outlet 9 establishing the hydraulic communication with a slave hydraulic cylinder adapted to actuate a clutch Said pressure outlet 9 is formed by a tubular connection integrated into the body 2, 40 relating to the cylindrical periphery of its end a thread used to connect the connecting pipe and and crossed by the

channel 11.

  The bore 3 comprises a small diameter portion 12 and a large diameter portion 13 The small diameter portion 12 forms the working chamber 7 and can be used to guide the end 14 of the piston 4 to the working chamber side The transition between the parts 13 and 14 is formed by a shoulder 15 in which a channel 16 which is connected to a feed tank, not shown in the figure, is opened by a connection pipe 17 molded by injection on the body 2 From the c 8 tee of the open end 5 of the master cylinder 1, the valve system 18 and the sealing device 19 are guided in the part 13 of

the bore 3.

  The valve system 18 is composed of an annular seal 21 prevulcanized on the end face of an annular disc 20, a spacer ring 22 placed after the annular disk 20 towards the open end 5 and A valve spring 23 The valve spring 23 concentrically surrounds the spacer ring 22 At the end of the spacer ring 22 and the valve spring 23 is a guide ring 24 which on the other side , is adjacent to the sealing device 19 and prevents the displacement of the valve system 18 towards the open end 5 This guide ring 24 comprises projections 25 of the same diameter directed towards the working chamber 7 whose radially outer periphery s' presses on the radially inner periphery of the valve spring 23 and thus serves as a guide to the valve spring 23 This guide ring 24

  is guided by the wall of the portion 13 of large diameter of the bore.

  At its end 14 of the c 8 tee of the working chamber, the pis30 ton 4 has a shoulder 15 on which rests the annular seal 21 In the rest position of the maltre-cylinder 1 illustrated in Figure 1, the surface d sealing of the annular seal 21 extends for a short distance in front of the shoulder 15, into which the channel 16 opens, so that there is hydraulic communication between the supply tank subjected to the atmospheric pressure and the This hydraulic communication goes from the channel 16 to the space 28 formed between the piston 4 and the bore 3.

  passing through the annular chamber 27 which is formed between the shoulder 15 and the sealing surface 26.

  In this embodiment, said sealing device 19 is

  composed of a plastic spacing sleeve 29, which is guided in the portion 13 of the bore and which carries at its end located on the side of the valve system 18 an axial recess 30 containing an annular seal 31, the latter pressing in a pressure-resistant manner against the peripheral surface 32 of the piston 4.

  Viewed in the direction of actuation maltre-cylinder 1, a radial groove 33 carrying an annular seal 34 is provided in the radially outer periphery of the spacer sleeve 29 in front of the axial recess 30 This ring seal 34 provides a sealing function against the wall of the portion 13 of the bore relative to the spacer sleeve 29 The sealing device 19 seals the working chamber 7 relative to the atmosphere.

  On the radially outer periphery in the region of the open end 5, the body 2 has a thread 35 on which is screwed a substantially pot-shaped sleeve 36.

  The bore 38 formed in the bottom 37 of the bushing 36 is traversed by the rod 39 of the piston 4. Due to the force applied by the valve spring 23, this bushing 36 is constantly bearing against the end surface 40 of the piston. bottom 37 facing the working chamber 7 Due to this sleeve 36, the valve system and the sealing device 18, 19 are held in a fixed position

in part 13 of the bore.

  The body 2 of the master cylinder 1 is held in a flange 41 made of metal sheet and centered on the body 2, which is firmly fixed by the sleeve 36 against the abutment surface 42 formed on the body 2 The centering surface 43 formed on the body 2 for centering the flange 41 is provided with a radially inwardly facing indentation 44, in which a corresponding projection 30 of the flange 41 engages. This flange 41 has bores 46 distributed over its periphery, these holes serving to receive fastening screws not shown in the figure, by

  which the master cylinder 1 can be fixed for example to the deck of a motor vehicle.

  At the end of the rod 39 integrated in the piston 4 and leaving the open end 5, the lock washer 48 is fixed using

  The spring 49 is supported on the lock washer 48 and the bushing 36, this spring serving to return the piston 4 to its initial position shown after each actuation of the master cylinder 1.

  A longitudinal groove 50 extending in the longitudinal direction of the master cylinder 1 is formed in the upper part (looking at the drawing) of the wall of the small diameter portion 12 This longitudinal groove 50 serves to ensure a correct supply of fluid at the return of the piston 4 This longitudinal groove 50 is necessary if the space 28 must be small to ensure proper guidance of the piston 4 in the portion 12 of small diameter However, it is also possible to replace the longitudinal groove 50 by slots distributed over the periphery of the end 14 of the piston 4 of the c 8 tee of the working chamber 7, these slots extending from the working chamber 7 to

the shoulder 51 of the piston 4.

  The fact that the piston 4 enters the valve system 19 and engages behind it its end 14 on the side of the working chamber 7 allows the piston 4 to actuate the valve system 18 to

using the shoulder 51.

  The cross-sectional views of the master cylinder constructions shown in FIGS. 2 to 4 differ slightly in the respective components of FIG. 1, so that the components corresponding to those of FIG.

  identical references To avoid repetition, only differences will be addressed.

  In FIGS. 2 and 3, the bushing 36 is a piece of metal cut and formed, surrounding the radially outer periphery 52 of the cylindrical end of the body 2 with a preload and resting by its bottom 37 on the surface. This bushing 36 comprises two diametrically opposite retaining arms 53, 54 which extend substantially in the direction of the closed end 8 of the cylinder-cylinder 1 30 and engage with them. end 57, 58 behind projections

  radially outwardly facing 55, 56 of the peripheral surface 52 of the body 2 Between the ends 57, 58 and the projections 55, 56 is clamped the radially inner portion of the flange 41 which is thus mounted rigidly on the body 2 through the bushing 36.

  Fig. 3 illustrates the baluster mount device of

  FIG. 2 after pivoting 90 of the plane of the drawing. In order to allow the flange 41 to be passed over the projections 55, 56, circular notches 59, 60 are provided in the vertical plane of the drawing. simple and easy manufacturing.

  In FIG. 4, a cylindrical pivot 61 traversed by the channel 11 rises on the bottom of the closed end 8 and in the working chamber 7. On said cylindrical pivot o 6 the plug 62

  which is guided and maintained in the channel 11 by an extension 63.

  To allow the flow of fluid between the channel 11 and the working chamber 7, the plug 62 has for example a cross-sectional shape.

  The maltre-cylinder operating mode according to the invention is as follows.

  When actuating the piston 4 to the left, according to Figure 1, the annular seal 21 moves in the same way to the left until it abuts on the shoulder 15 and closes tightly. the channel 16 When the piston 4 continues to be actuated, its shoulder 51 rises from the sealing surface 26, and the pressurized fluid is sent in the channel 11 to the slave cylinder of a clutch not shown, the The pressure in the working chamber 7 can cause a radial expansion of the body 2 made of plastic material to prevent this expansion at the device.

  19 that could cause leaks, the metal sleeve 36 surrounds the end portion of the body 2.

  During the return stroke, the sequence of movements is reversed. Retraction of the play of the slave cylinder, for example due to wear of the linings, is effected by drawing fluid into the working chamber 7 via the channel 16. in most cases, this action does not occur before the piston 4 has disengaged the annular seal 21 of the shoulder 15 Si, despite any need for suction more t 8 t, the pressure below the pressure atmospheric reigning in the working chamber 7 automatically causes an opening of the valve system 18 in opposition to the force of the valve spring 23 For a predetermined valve spring 23, this action can be facilitated by increasing the

  section of the channel opening into the shoulder 15 The longitudinal groove 50 formed in the portion 12 of small diameter of the bore increases the flow section between the bore 3 and the piston 4.

  During the return stroke of the piston 4, the spring 49 guarantees a

  safe opening of the valve system 18.

Claims (4)

claims   1 Malter-cylinder, particularly for the hydraulic actuation of the clutch of a motor vehicle, comprising a body made of plastic material and provided with a flange, a piston being movable in a bore by a control rod and sealingly associated with this bore and a valve system operable by the piston and connecting a compensation chamber to a pressure chamber, when the master cylinder is in the rest position, by a channel which can be closed when the valve system is actuated, characterized in that the peripheral surface (52) of the body (2) is firmly held by a metal sleeve (36) at the piston seal (31) and that the flange (41) made of metal is placed on the body (2) and is locked by the sleeve (36) against   a stop (55, 56) on the body (2).   Master cylinder according to claim 1, characterized in that the bushing (36) is substantially pot-shaped and is connected to the body (2) by a balancer-type engagement (55, 56 and 57, 58 then that the radially inner end of the flange (41) is locked between the stops of the bayonet mount (55, 56 and 57, 58) and that the bottom (37) of the socket (36) maintains the valve (18), the sealing device (19) and the piston   (4) and prevents them from escaping.   Master cylinder according to claim 2, characterized in that the flange (41) is arranged to be fixed to the body (2) by means of a mechanism preventing rotation (44, 45). according to claim 2, comprising a spring bringing the piston back to its rest position, characterized in that the spring (49) is disposed outside the body (2) and on one side bears against the body ( 2) and the other side bears against   an end washer 8 t (48) of the piston (4) coming out of the body (2).   Malter-cylinder according to any one of the preceding claims, characterized in that a plug (62) can be attached to the closed end (8) of the bore (3).   A cylinder drum according to any one of the preceding claims, characterized in that a sleeve extending into the chamber of   work (7) is provided at the closed end (8) of the bore (3).