FR2755736A1 - HYDRAULIC RELEASE DEVICE WITH ANNULAR PISTON PROVIDED WITH A SEAL - Google Patents

Abstract

Hydraulic release device for a friction clutch. It comprises a pressure box (3) with a pressure chamber (8) in a ring of a circle housing an annular piston (9) urged by pressurized fluid to slide axially. The sealing of the annular piston in the pressure chamber (9) is ensured by a reinforced seal (12) provided by a connection by the form on the annular piston (9). According to the invention, the seal (12) has a frame member (13) in the form of a roof having two axially distant edges, and directed towards the annular piston (9).

Description

The present invention relates to a device for

  hydraulic clutch for a friction clutch of a vehicle

  cule, comprising a declutching system having a housing

  pressure locked in position on the gearbox, the bol-

  pressure tier being mounted concentrically with a drive shaft connecting the internal combustion engine to a pinion gearbox, to produce a pressure chamber in the form of a ring, with in a longitudinal bore of the pressure housing, a guide sleeve radially spaced both from the wall of the bore and from

  the drive shaft, sleeve on which is guided in

  axial smoothing a piston axially delimiting the

  pressure, and to seal the pressure chamber

  There is a reinforced seal on the side of the pressure chamber, a seal whose lips seal a sealing gap forming a sealed sliding surface between the wall of the longitudinal bore and the annular piston as well as between the guide sleeve and the annular piston. Technological background of the invention

  According to the state of the art constituted by the do-

  cument DE-41 30 525 Al, there is known a declutching device with a grooved ring comprising a reinforcing element in

  form of support ring coming against the front face of the pis-

  your ring finger. This construction allows the annular piston, as part of its radial guide clearance, to execute a

  eccentric movement with respect to the longitudinal axis of the arrangement

  declutching device. The friction connection between the face

  front of the annular piston and the armature element can

  due to the fact that in the event of a radial offset of the annular piston,

  the seal also shifts in an uncontrolled manner

  sant to a strong stress, annoying of the joint in particular

  tie sealing lips. In the event of high pressure in the system, this displacement of the seal causes a greater

  wear of the seal lips leading to a malfunction

  failure or failure of the seal due to this

heavy wear.

  Another annular piston seal is described in utility model DE-18 40 727, the frame of which is adapted to an annular piston with a stepped front face. The

  joint is provided with a central part forming a front surface

  flat plate on the side of the pressure chamber, followed by a V-shaped cavity to each time form a sealing lip; this cavity rests against a rod or a wall hole. Due to the curved reinforcement element, we come to different wall thicknesses for the joint which then expands differently depending on the pressure generated in the system, risking separating the reinforcement

vulcanized on the joint.

  OBJECT OF THE INVENTION The object of the present invention is to improve the tightness of a declutching system according to the state of the art by associating the seal with the annular piston precisely, in connection with a reinforcing element to obtain effective reduction of joint stress and thus

longer service life.

  Characteristics of the invention To this end, the invention relates to a device

  hydraulic declutching device of the type defined above, characteristic

  in that the seal has on its front face turned towards the annular piston, a roof-shaped reinforcement element, having two edges axially spaced and turned in the

direction of the annular piston.

  The roof-shaped reinforcement element which continues with axially spaced edges which pass coaxially to the longitudinal bore. The frame element in

  the roof shape advantageously ensures a reduction in

  joint expansion teeth and thus stresses

  citing the seal at the attachment surface of

  the armature which increases the time of use, that is to say

say the life of the seal.

  The structure according to the invention further provides that the reinforcing element bears exclusively against the annular piston by axially spaced edges; this gives the seal a more efficient attachment to the annular piston. The realization of the frame according to the invention

  can be obtained by guiding the seal on the annealed piston

  the milk prohibiting at the same time any eccentric movement of the annular piston which would have an annoying effect on the seal due to the increase in wear of the seal. According to a preferred embodiment of the invention, the roof-shaped reinforcing element has an apex placed in the middle of the joint. There is thus a line of force or force transmission, straight for the seal on the annular piston. In addition, the segments of the frame which form a roof structure meet. This shaping also reinforces the requirement for effective centering of the joint. Thanks to the roof-shaped frame, the annular piston is also surrounded peripherally by the frame element to achieve optimum support for the seal.

  on the annular piston. By calculation, we were able to define the

  their optimum of angle a, between 10 and 45 per ratio * -

  bearing in the transverse median plane of the joint, angle at which the segments forming the roof shape are provided

on the frame.

  According to another characteristic, in order to reduce the stress on the joint, it is provided that all the passages of the reinforcing element between the segments and the edges must be rounded and thus reduce the gradients of expansion of the joints on the attachment surface of the reinforcing element which also has a positive effect

on the joint directive.

  According to another development of the invention, the front face of the annular piston facing the reinforcing element is of convex shape. This embodiment promotes optimum centering of the frame member of the seal as well as a surface support, desired for the frame member against the annular piston; this also compensates for the manufacturing tolerances between the cooperating parts, the reinforcing element and the annular piston. The domed shaping of the front face on the side of the annular piston constitutes an interesting compromise compared to the wish consisting in making the front face exactly identical to the shape of the roof of the reinforcing element since this would not be possible.

  only with very complicated manufacturing and measuring means

  ques. Alternatively, a domed front face of the annular piston

  this surface can be conical and thus have practically a shape adapted to the shape of the roof of the frame. A preferred embodiment of the invention provides for the edge of the armature located radially at

  outside, an axial extension towards the piston an-

  nular. At the free end, the edge is provided with an elastic retaining spout which hangs in the mounting position

  of the seal in a cavity of the annular piston. The rete beak

  bare provided on the side of the end of the edge, thus constitutes a radial undercut ensuring effective fixing by a form connection between the reinforcing element and the

  annular piston. By an appropriate form and / or- a dimen-

  adequate siting of the cavity in the annular piston and of the retaining spout, it is thus possible to have an axial clearance of

  reinforcement and limited axial mobility of the joint compared to

  port to the annular piston. To fix the axial clearance which in

  certain circumstances is necessary for the

  clutch, the width of the peripheral groove in the annular piston exceeds the length of the retaining spout. In addition, the edge provided with the retaining spout is spread radially

  limited compared to the annular piston which allows

  place the gasket including the armature relative to the annular piston. According to another characteristic of the invention, the reinforcing element, that is to say the roof-shaped edges

  are surrounded by a sealant on the side of the chamber

  pressure. This means increases the surface area for attaching the sealing material to the reinforcement element, while also avoiding any unfavorable contact between the reinforcement element and the guide sleeve or the guide hole in the

pressure box.

  As another means, the invention provides a form of seal whose sealing lips are asymmetrical and have different lengths. This embodiment allows equal stress, that is to say frictional forces which correspond for all the sealing lips separated from one another in the assembled state. In addition, the two

  sealing lips have a rounded sealing edge, bom-

  open in an unassembled state. As a result of this embodiment, the frontal area each time outside of each sealing lip lifts relative to the bearing surface of the sealing lip, in the assembled state. This property avoids

  that the joint does not twist and thus promotes the tightness

read by the seal.

  The structure of the seal according to the invention further comprises a V-shaped cavity between the sealing lips from which the front faces of the lips face radially outward, coming from

  protruding into the range of the edge areas.

Summary description of the drawings

  An exemplary embodiment of the invention is shown

  shown in the drawings and will be described below. Thus: - Figure 1 shows a hydraulic declutching device integrated into a seal according to the invention, - Figure 2 shows on an enlarged scale, the detail "Z" of Figure 1, - Figure 3 is a detail drawing of the seal according to the invention hung on an annular piston, - Figure 4 shows a seal section showing the

  stress distribution in the assembled state.

Detailed description of the drawings

  Figure 1 shows a hy- clutch release

  hydraulics of known construction, in assembled state. The system

  clutch 1 attached by flange to the body of the gearbox

  braids 2 mainly includes a pressure box 3 in-

  concentrically rotating the drive shaft 4 connecting a gearbox geared in the gearbox 2 and an internal combustion engine not shown in Figure 1. A radial distance from the drive shaft 4 and a longitudinal bore 5 of the pressure unit 3, there is a guide sleeve 6 fixed in position by an annular flange 7 between

  gearbox 2 and pressure unit 3. One

  pressure bre 8 in the form of a circular ring is provided

  be the longitudinal bore 5 and the guide sleeve 6.

  This chamber is axially limited by the annular flange 7 and by an annular piston 9. To slide the annular piston 9 axially in the direction of the arrow to actuate a friction clutch not shown in FIG. 1,

  a pressurized fluid is introduced into the pressure chamber

  8 through the supply line 10. At its end

  mite opposite to the pressure chamber 8, the annular piston 9 is provided with a declutching bearing 11 connected to the declutching means of the friction clutch. To make the pressure chamber 8 sealed, the annular piston 9 has a

  seal 12 in the form of a groove seal fixed in a solid

  preferably by vulcanization on an element

of reinforcement 13.

  To explain the structure of the joint 12 according to the invention, FIG. 2 shows on an enlarged scale the detail "z" in FIG. 1. This enlarged drawing shows the roof-shaped structure of the reinforcing element 13 formed by the segments 14, 15 continuing with an edge 16, 17 each time coaxial with the longitudinal bore 5. The frame element 13 in the form of a roof penetrates through its top 33 into the joint 12. The edge 16 which is located on the side pressure box 3 and has an axial length greater than that of the edge

  17, includes a retaining spout 18. This retaining spout 18 reacts

  read by stamping without removing material or by punch-

  swims in the edge 18 hooks into a cavity 19 of the annular piston 9 and thanks to a part undercut or to a radial overlap 30, 31 corresponding to the reference "y" as well as an axial clearance between "x", comes against a shoulder 20 of the cavity 9 by fixing the seal on the piston

  annular 9 by a form connection.

  A front face 21 of the annular piston 9 is reduced to adapt with radial play in the shape of the roof of the reinforcing element 13. The front face 21 is of convex shape so that the reinforcing element 13 bears against the annular piston by relatively large contact surfaces 22, 23. The seal 12 is provided with sealing lips 24, 25 of asymmetrical shape and between which there is a cavity 33 with a V-shaped section. The sealing lip 24 directed radially outwards towards the

  pressure box 3 is larger than the lip

  sealing glass 25 to arrive at identical friction conditions. The differences between the sealing lips thus compensate for the differences in diameter of the

  lips and so the effects of pressure that differ so

  if. The two sealing lips 24, 25 have an edge

  sealing 26, 27 of convex shape that an adaptation

  optimal tion or optimum support of the sealing lips 24, against the wall of the longitudinal bore 5 or of the envelope surface of the guide sleeve 6. The shape of the sealing edges means that in the assembled state, there remains a edge zone 28, 29, i.e. one end of the edge

  seal 26, 27 is spaced from the wall of the long hole

  tudinal 5 or the envelope surface of the guide sleeve 6.

  The overlap 30, 31 explains the difference in dimension existing between the sealing edges 26, 27 in the assembled state

and in the unassembled state.

  Figure 3 shows the seal 12 in the unassembled state explaining other details in particular the element

  of reinforcement 13. This one has strongly ar-

  rounded at the level of the roof area, that is to say at the top 32 where the segments 14, 15 meet as well as between the bottom 16, 17 and the segments 14, 15. This shape given to the element reinforcement 13 significantly reduces

  expansion radii and thus the stress on the joint; this-

  the advantageously affects reliability and thus the life of the seal according to the invention. The structure of the joint also shows that the segments 14, 15 in the form of

  roof, each making an angle "a" of 10 to 45 relative to

  port to the longitudinal axis 12 come to take by the top 32 in the middle in the joint 12 which establishes an application

  the force of the annular piston along a straight line.

  To increase the attachment surfaces, the sealing material surrounds the reinforcing element 13 on the side of the

  pressure chamber starting at edge 17 with seg-

  elements 14, 15 up to part of the edge 16.

  FIG. 4 explains the tension conditions which are established in the joint in the operating position for a maximum operating pressure. There is a relatively low, regular voltage distribution at the segments 14, 15 which gives a roof shape shown

  by a very largely constant gray tint. The distribution

  tion of the tension has a positive influence on the reinforcing element 13. In addition, the practically concordant tension states according to FIG. 4 for the sealing lips 24, 25 show that they ensure optimum sealing and the same friction conditions are established at the level

sealing edges 26, 27.

  Finally, it should be noted that the sealing edges 26, 27 form in the assembled state, an edge region 28, 29 and these edges are aligned radially, at a distance from the respective bearing surface of the lips.

sealing 24, 25.

NOMENCLATURE

  1 Clutch release system 2 Gearbox 3 Pressure box 4 Drive shaft Longitudinal drilling 6 Guide sleeve 7 Ring flange 8 Pressure chamber 9 Annular piston Supply line 1il Release bearing 12 Seal 13 Reinforcement element 14 Segment Segment 16 Edge 17 Edge 18 Retaining spout 19 Cavity Shoulder 21 Front face 22 Contact surface 23 Contact surface 24 Sealing lip Sealing lip 26 Sealing edge 27 Sealing edge 28 Edge area 29 Edge area Overlap 31 Overlap 32 Top 33 Cavity a Angle made by the segments x Axial clearance y Radial overlap

R E V E N D I CATIONS

  1) Hydraulic declutching device for a friction clutch of a vehicle, comprising a declutching system (1) having a pressure box (3) locked in position on the gearbox (2), the pressure box (3 ) being mounted concentrically with a drive shaft (4) connecting

  the internal combustion engine has a low-speed gearbox

  gnon, to produce a pressure chamber (8) in the form of a circular ring, with in a longitudinal bore (5) of the

  pressure box (3), a guide sleeve (6) spaced apart

  both the hole wall and the shaft

  drive (4), sleeve on which is guided in sliding

  axially an annular piston (9) axially delimiting the pressure chamber (8), and to ensure the tightness of the pressure chamber (8), there is provided an armored seal (12) on the side of the pressure chamber, seal whose lips (24,

  ) seal a tight sealing interval

  mant a sealed sliding surface between the wall of the

  longitudinal bore (5) and the annular piston (9) as well as between the guide sleeve (6) and the annular piston (9), characterized in that the seal (12) has on its front face facing the annular piston (9), a reinforcing element (13) in the form of a roof, having two edges (16, 17) spaced apart axially and turned

  in the direction of the annular piston (9).

  2) Hydraulic release device according to the claim

tion 1, characterized in that

  a top (12) of the reinforcing element (13) is placed in the middle

place of the joint.

  3) Hydraulic release device according to the claim

  tion 1, characterized in that 1! the reinforcing element (13) bears against a front face

  (21) of the annular piston (9) by the segments (14, 15) giving

nant the form of roof.

  4) Hydraulic declutching device according to claim 2, characterized in that the segments (14, 15) form an angle (a) between 10 and

    relative to a transverse plane of the joint 12.

   ) Hydraulic declutching device according to claim 1, characterized in that the junctions between the segments (14, 15) as well as between the

  edges (16, 17) and the segments (14, 15) are rounded.

  6) Hydraulic declutching device according to the claim

  tion 1, characterized in that the front face (21) of the annular piston (9) facing the reinforcing element (13) is of convex shape to ensure centering.

  7) Hydraulic declutching device according to the claim

tion 1, characterized in that

  the front face (21) of the annular piston (9) is conical.

  8) Hydraulic release device according to the claim

tion 1, characterized in that

  the edge (16) of the reinforcing element (13) facing the box

  pressure tier (3) and which is radially

  the outside is extended axially on the side of the annealed piston

  and has a retaining spout (18), elastic hooking in the mounting position of the frame (13) in

  a cavity (19) of the annular piston (9).

  9) Hydraulic release device according to the claim

tion 8, characterized in that

  the reinforcing element (13) is held on the annular piston

area (9) with axial play.

   ) Hydraulic release device according to the claim

  tion 1, characterized in that the reinforcing element (13) is surrounded by the material

  seal on the pressure chamber side.

  11) Hydraulic release device according to the claim

tion 1, characterized by

  sealing lips (24, 25) arranged asymmetrically

  stick, the sealing lip (24) radially on the outside being thicker than the sealing lip (25) radially

inside.

  12) Hydraulic release device according to the claim

  tion 11, characterized in that the sealing lips (24, 25) have a sealing edge

  (26, 27) curved, rounded in the unassembled state.

  13) Hydraulic release device according to the claim

  tion 12, characterized in that the sealing edges (26, 27) form in the assembled state, an edge area (28, 29) and these edges are aligned radially, at a distance from the bearing surface respective of

sealing lips (24, 25).

  14) Hydraulic release device according to the claim

  tion 11, characterized by a cavity (32) with a cross-section (V) between the lips

  seal (24, 25) and from which the front faces

  respective tales of the sealing lips (24, 25) come

  projecting towards the edge zones (28, 29) located radially

lie outside.