FR2757234A1 - MASTER CYLINDER FOR FRICTION CLUTCH OR HYDRAULIC VEHICLE BRAKE - Google Patents

Abstract

Master cylinder (1) for a hydraulically operated friction clutch comprising a housing (2) housing an axially sliding piston (8). The piston (8) is connected by a rod (12) to an actuating means. The piston (9) defines with the housing (2) a pressure chamber (10) connected directly to a pressure outlet (4) and indirectly to a breather connection (3). The cylinder (1) comprises a primary seal (16), the radially outer sealing lip (18a) of which penetrates into a peripheral groove (19a) of the housing (2); the width or depth of the groove exceeds the wall thickness of the lip (18a). The lip makes it possible, independently of the pressure prevailing in the pressure chamber, to ensure the sealing of this pressure chamber (10) or fluid communication between the connection (3) and the pressure chamber (10).

Description

Field of the Invention The present invention relates to a master cylinder

  for a friction clutch with hydraulic control or vehicle brake comprising a housing accommodating in axial sliding a piston and U-shaped seals, with lips comprising a primary seal and a secondary seal ensuring the seal,

  the piston being connected by a piston rod to a foot pedal

  particularly manually and the piston forms on the front side, a pressure chamber of variable volume with the

  housing, this chamber communicating directly with a branch

  pressure and indirectly with a sniffer connection. Technological background We know a master cylinder corresponding to the type defined above according to document DE-A-37 38 741. For

  perform volume compensation between the pressure chamber

  sion and a fluid reservoir, the piston has a non-return valve. The non-return valve provided frontally on the piston and going into the pressure chamber is connected by a blind bore and a transverse bore of the piston as well as by a sniffer connection from the housing to a liquid reservoir; it opens automatically as soon as the pressure in the breather connection is higher than the pressure in the pressure chamber. The non-return valve allows automatic compensation of the fluid under

  pressure as a function of leaks in the pressure chamber.

  This known non-return valve influences the axial length of the

  piston and thus that of the master cylinder. The check valve

  The known tower also has an awkward influence on the construction

  tion and manufacturing and assembly work which

  globally increases the manufacturing cost of this master

lindre known.

  The object of the present invention is to create a master

  tre-cylinder optimized by its size and its parts, of-

  frant an easy construction and less expensive than

known master cylinders.

  Disclosure of the invention This problem is solved according to the invention by a master cylinder characterized in that a sealing lip, radial outside of the primary seal, enters the mounting position in a peripheral groove of the housing, the width and the depth of the groove exceeding the wall thickness or a longitudinal extension of the sealing lip and the sealing lip allows the establishment of a pressure in the pressure chamber ensuring the sealing of the pressure chamber or communication between the pressure chamber and

the sniffer connection.

  This problem is also solved by a master

  cylinder of the type defined above, characterized by a lip

  external seal of the primary seal is applied

  frontally against the seal support or a U-shaped lip seal placed in the seal support with a support provided

  on the housing, on the opposite side, offset radially with respect to

  port at the free end, the sealing lip allowing, depending on a pressure being established in the pressure chamber, to seal the pressure chamber or to allow the communication of the fluid between the chamber of

  pressure and sniffer connection.

  A master cylinder according to the invention such as

  finish above thus includes a primary seal placed in a seal holder and whose sealing lip, radially

  outside penetrates in the mounted state in a peripheral groove

  that of the case. The width of the groove exceeds the thickness

  of the lip wall. The sealing lip, radially ex-

  of the primary seal is conducted in the neutral position

  as well as by actuating the master cylinder against the

  outer king of the peripheral groove of the case. The pa-

  inner king of the peripheral groove so enters

  a U-shaped interval, rotated over a very wide range

  of 90, which exists between the inner lip and the outer lip of the primary seal. Advantageously, the lip

  sealing of the primary seal allows depending on the pressure

  sion established in the pressure chamber or a diff-

  pressure ference, to seal the pressure chamber or to allow fluid communication between the pressure chamber and the breather connection. The radially outer sealing lip of the primary seal performs two functions. When the master cylinder is actuated, the axial displacement of the piston creates a pressure build-up in the pressure chamber and the sealing lip ensures effective sealing. At the end of the clutch operation, when the piston returns to the end-of-travel position, the sealing lip allows, for example, liquid to arrive in the pressure chamber, as soon as the tank pressure

  is higher than the pressure in the pressure chamber

  to compensate for leaks. The invention thus transmits to the primary seal usually placed in the master cylinder, the role of non-return valve, which results in the desired reduction in the number of parts. The primary seal surrounding the piston performs two functions; it in no way influences the axial length of the piston and makes it possible to optimize the overall dimensions. The invention further promotes mounting this

  which generally gives a master cylinder of advantageous cost.

  The realization of the peripheral groove in the housing, with a groove width greater than the thickness

  of the sealing lip wall, allows the exhaust

  dial of the sealing lip in relation to the outer wall

  when the liquid from the reservoir arrives in the direction of the pressure chamber. The inner wall of the peripheral groove thus fulfills the role of a lip guide which may be necessary in the event of an abrupt return of the piston, for example if the foot slides off the accelerator pedal resulting in a sudden depression

  in the pressure chamber, which can trigger a displacement

  uncontrolled sealing lip influencing

  tightness when the master cylinder is actuated later

  laughingly. According to a development of the invention, there is a primary seal whose axial length of the outer lip

  exceeds the length of the inner lip. This construct-

  tion allows to have an outer sealing lip, radia-

  Lely elastic, advantageously flexible and which during the establishment of the pressure participates effectively in

  sealing by applying tightly against the

  outer king of the peripheral groove and in case of

  pressure, caused by a pressure drop between the tank and the pressure chamber, this lip moves radially practically without resistance and thus allows

  the arrival of pressurized fluid in the pressure chamber

  if we. In case of depression or pressure difference, the

  radially outer lip of the primary seal is supported

  be the inner wall of the peripheral groove or against the extensions integral with the inner wall and

  axially projecting from the inner wall.

  In the outer wall as well as between the pro-

  lengths associated with the inner wall there are radial slots distributed at the periphery, through which

  when the sealing lip is lifted from its watertight support

  che, allows the passage of fluid for re-aspiration. The split area of the outer wall has on one side a

  ramp shape which establishes a conical profile going di-

  minuant along a cone from the free end di-

  rection of the bottom of the groove. In the assembled state, a front segment of the sealing support, elastically deformable

  leans against this ramp to achieve better water resistance

  and create a radial component acting on the

primary seal.

  As a means of creating a flow-promoting inlet or a fluid connection between the pressure chamber and the suction branch, before reaching the end position of the piston, the inner wall of the axial groove is provided with the side turned towards the piston, at least one longitudinal groove widening conically in the direction of the seal support, and reaching into the pressure chamber. This means allows compensation

  fluid on a piston stroke segment, extended, al-

  lant from the tank to the pressure chamber.

  According to another advantageous development of

  the invention, the pressure chamber has a groove lon-

  gitudinal extending from the inner wall to the bottom of the

  side of the front face of the pressure chamber. The reason

  longitudinal connection thus communicates with a pressure connection. This means a further improvement in the

  behavior for additional suction filling

  shut up or to suppress the strangulation. As an alternative arrangement of the primary seal, the invention provides that the outer sealing lip is applied practically over the entire axial length, in the normal state as well as in the pressurized state against the outer wall of the peripheral groove . For this, the seal

  primary can be provided directly on the piston. This my-

  The seal does not require any separation of the parts in the housing. In addition, the interior static seal

  can be shortened using this method.

  To apply precise pressure to the outer sealing lip, which in the event of possible depression

  in the pressure chamber must allow the complete arrival

  ment of pressurized liquid by a radial escape from the sealing lip, offset inwards, the outer wall is provided with supply grooves. These supply grooves are provided axially with a distribution

  peripheral and starting from the sniffer connection, these

  nures are continuously decreasing towards the peripheral groove. All feed grooves

  open into a peripheral groove made in the

  outer king at an axial distance from the free end of

the sealing lip.

  The master cylinder comprises a primary seal, the radially outer sealing lip of which is aligned

  vertically, presses by the front face against the support

  seal port or against a U-shaped lip seal placed in the

  joint support. The radially outer sealing lip

  of the primary seal allows the liquid to pass from the

  serve in the pressure chamber by lifting off the sealing surface of the seal support or the U-seal. To guarantee a predetermined mounting position of the primary seal and to have an unimpeded lifting of the sealing lip, the housing is provided with a seal support provided with radial offset with respect to

  the free end of the sealing lip. The invention

  globe thus a partial arrangement or an annular support, with radial grooves or slots made possible by a fluid passage without obstacle. The seal support or the U-seal are sealed relative to the housing by a round seal placed in a peripheral groove. To create communication between

  breather connection and radial sealing lip-

  outer seal of the primary seal, the seal holder is

  provided with practically peripheral fluid channels, i.e.

  say that on the front face of the side opposite the primary seal

  mayor, on the piston side and in the area of the receiving cavity

before the primary seal.

  A contact surface or sealing surface determined between the sealing lip and the seal support improves the seal and for this the seal support or the

  sealing lip has a perimeter sealing bead

  spherical whose sealing surface may vary depending

  applied pressure conditions. Alternatively, the sup-

  seal port may also include a sealing bead. According to another development of the invention, the seal support is provided with a separate rendered seal receiving the annular seal, in particular the round seal to ensure

  the seal support in relation to the housing. This-

  it is preferably glued or fixed by ultrasonic welding to the U-shaped joint connected to the joint support allows by

  example of using materials that suit advantageously-

  to achieve an optimal seal. The shaping and the realization of the U-joint are advantageously designed

  so that the sealing area of the radiating sealing lip

  outside the primary seal applies exclusively

  against the front face of the U-joint. This means or combination

  sound with the mouth of the fluid channel near the free end of the sealing lip made in one

  very elastic sealing material, and for low de-

  pressure ensures that even in the pressure chamber or

  for a pressure which in the tank only exceeds slightly

  Rely that in the pressure chamber, one can have a liquid arrival compensating for the leaks. Summary description of the drawings

  The present invention will be described below in

  using four exemplary embodiments shown diagrammatically

  tick in the accompanying drawings in which:

  - Figure 1 is a longitudinal section of a master-

cylinder according to the invention,

  - Figure 2 shows a primary seal according to the invention pla-

  cé in a seal support, - Figure 3 shows a detail in front view of the seal support according to Figure 2,

  - Figure 4 shows a sectional view of the primary seal, se-

ready,

  FIG. 5 is a longitudinal section of the master housing

  tre-cylinder of FIG. 1, FIG. 6 is a view along X of FIG. 5, FIG. 7 shows an enlarged view of the detail Y of FIG. 5, FIG. 8 shows the detail Z of the Figure 5 on an enlarged scale, - Figure 9 shows a variant of the detail Y of Figure 5, - Figure 10 shows an alternative embodiment of the detail Z of Figure 5, - Figure 11 shows an alternative embodiment of the joint

  primary in Figure 1, including the sealing lip, radia-

  Lement to the outside is applied in a leaktight manner in a U-shaped joint of the joint support, - Figure 12 shows a joint which corresponds very largely to that of Figure 1, with however the primary seal housed in the joint support unlike in Figure 9, - Figure 13 shows a master cylinder whose structure corresponds to that of the master cylinder of Figure 12 with

  only a difference of the fluid channels in the sup-

seal port.

Detailed description of the drawings

  According to FIG. 1, the reference 1 designates a house

  tre-cylinder in longitudinal section, comprising a housing preferably made of plastic. A sniffer connection 3 connected to a reservoir not shown in Figure 1, allows

  to supply master cylinder 1 with incoming hydraulic fluid

  by a connection 4 of a receiving cylinder not shown

  felt in Figure 1 of the hydraulic actuator.

  A radially stepped blind bore 5 is produced in the housing 2; the larger diameter range of this hole comprises a guide sleeve 6 with a sliding piston 8

  in the inner wall 7 of this sleeve. The mistletoe sleeve

  dage 6 is placed axially in front of a seal support 9 in the housing 2; this sleeve also guides the piston 8. The front face of the piston 8 defines with the housing 2, a

  pressure chamber 10 filled with fluid; during the coulis-

  sement axially of the piston 8, the fluid arrives in the direction of the arrow by the connection 4 in a receiving cylinder to actuate the friction clutch. When the piston 8

  is in neutral position, i.e. when the master-

  cylinder 1 is not actuated, piston 8 is applied con-

  be the end of travel stop 11 of the guide sleeve 6.

  The piston 8 comprises a sleeve 13 forming the piston body, made of sheet metal which comprises two half-shells 14a, 14b with each time cavities in the form of caps at the end opposite to the pressure chamber 10, designed to receive a head of the ball of a piston rod 12. The rod

  piston 12 is made in one piece of plastic material

  tick and makes the connection between the piston 8 and a device

  manually operated pedal not shown in the figure

  1 or an electric / hydraulic actuator.

  To seal the pressure chamber

  sion 10 on the piston side, there is provided a primary seal 16 housed in a front cavity 15 of the seal support 9. The primary seal 16 produced as a U-shaped lip seal comprises two lips 17, 18a to be offset radially. The sealing lip 17, radially on the inside, is applied with prestress against an envelope surface of the sleeve of the piston body in a leaktight manner. The sealing lip 18a radially on the outside comes to take in a peripheral groove 19a of the housing and thus applies in a sealed manner against the external wall 20 of the axial groove 19a. On the front side, the primary seal 16 is supported between the sealing lips 17, 18a, against axially projecting extensions 30 of the inner wall 21, between the sealing lips 17, 18a. The width or depth of the peripheral groove 19a exceeds the wall thickness of the

  sealing lips 18a. This embodiment allows a radial displacement of the sealing lip 18a in the groove

  device 19a. With the primary seal 16 is associated with axial offset, a secondary seal 22 introduced by the front face into the guide sleeve 6 and whose sealing lip 15 radially inside is also applied.

  with radial preload, tightly against the

piston shell surface 8.

  The sealing lip 18a and the peripheral groove

  rique 19a allow, thanks to their realization and their

  sition, a practically unobstructed flow of the fluid between the reservoir and the sniffer branch 3 in the pressure chamber 10, as soon as the pressure in the reservoir or in branch 3 is higher than that prevailing in

  the pressure chamber 10. For this, the fluid of the branch-

  Breather ment 3 can pass through a longitudinal groove 23 of the seal support 9 and a radial slot 24 of the outer wall 20 of the peripheral groove 19a and urge the sealing lip 18a through the radially outer face. Due to the pressure drop, the sealing lip 18a deforms in the direction of the inner wall 21 until it comes

  resting against the inner wall 21 or the extension 30.

  From the peripheral groove 19a, the fluid passes through windows

  your radials 25 made in the inner wall 21, in

  a longitudinal groove 26 of the housing 2. The long groove

  tudinal 26 decreases in a conical shape in par-

  both of the primary seal 16a in the direction of the

  pressure 10. Considering the position of the piston 8 represents

  tee in Figure 1, we arrive at a displacement of the piston 8 in the direction opposite to that of the arrow to connect the pressure chamber 10 to the longitudinal groove 6. If for example due to a leak, during the movement of the piston, a vacuum is established in the pressure chamber 10 or a pressure drop between the connection 3 and the pressure chamber 10, the chamber 10 is automatically filled with reservoir fluid thanks to the operation described above

  sealing lip 18. The housing 2 is provided with an

  be a longitudinal groove 42 extending from the bottom 43 to the length of the interior wall 21 while being connected to the

  connection 4. As an alternative or in addition to the longitu-

  dinal 26, a longitudinal groove 42 can be produced

in the housing 2.

  Figure 2 shows the primary seal 16 in the state

  assembled, on an enlarged scale. This figure makes clear

  Rement that the sealing lip 18a extends axially beyond the seal support 9. A cylindrical segment of the support

  seal 9 which surrounds the primary seal 16 at the level of the

  vity 15 presents externally a conical segment 27 which is supported in the assembled state, by a connection by the form against an outer wall 20 of corresponding shape of the housing 2

  having a ramp 28 (see Figure 7). The position and the dimen-

  the longitudinal groove 23 outside the

  seal support 9a appears in Figures 2 and 3.

  The detail drawing of the primary seal 16 according to FIG. 4 shows that the axial length of the sealing lip 18a significantly exceeds the length of the sealing lip 17 radially inside. In addition, the thickness of the wall of the sealing lip 18a is less than that of the sealing lip 17 which improves the desired elasticity of the sealing lip 18a, allowing a certain function of valve at a steering, as desired, in mounting position as has been

previously described.

  Figure 5 shows, in longitudinal section, the

  box 2 as a separate part. This achievement leaves

  the arrangement with peripheral distribution of the rai-

  longitudinal grooves 26 starting from the free end of the

  extensions 30 decreasing continuously up to the cham-

  compression bre 10. Between the extensions 30 provided axially projecting from the inner wall 21 and peripherally, there are each time radial slots 25 whose axial length corresponds to the axial length

  radial slots 24 made in the outer wall 20.

  Figure 6 shows the view in the direction X of Figure 5. This reveals in particular the peripheral distribution of the radial slots 24, 25 and thus the cavities provided in the housing 2 to arrive at a passage of fluid

  at the peripheral groove 19a. Next to the provision

  sition with symmetrical peripheral distribution of the radial slots 24, 25, Figure 6 also shows the arrangement

  symmetrical of the longitudinal grooves 26.

  FIG. 7 gives an enlarged view of the detail "Y" in FIG. 5. This figure clearly shows that the peripheral groove 19a reaches the wall of the

  housing 2 and that the radial slots 24, 25 of the outer wall

  wall 20 and between the extensions 30, extend each time over the entire axial length, wall segments of the peripheral groove 19a leaving the housing 2. The external wall 20 is further produced so as to end in the shape of a cone with the free end on the inner side to create a ramp 28 against which is applied by a shape connection, the front region of the seal support 9

in the assembled state.

  According to Figure 8, which shows on an enlarged scale the detail "Z", the peripheral groove 19a is shown in a different section from that of the detail "Y". The

  case 2 is cut in this case in the area of a flat slot

  diale 25. To create a favorable flow section of the peripheral groove 19a in the direction of the pressure chamber 10, the internal wall 21 is reduced to

  the thickness of the wall of the housing 2 and includes transi-

strongly rounded.

  Figures 9 and 10 show on an enlarged scale an alternative embodiment of the details "Y" and "Z" according to Figure 5. The housing 2 is provided with a peripheral groove 19b and the sealing lip 18 applies to the mounted

  against the outer wall 44 of this groove. To request

  ter the sealing lip 18, the wall ex-

  44 has feed holes 45 axially directed and distributed around the periphery. Starting from the start of the peripheral groove 19b, the supply bores 45

  continuously decrease to a peripheral groove 46.

  For a housing 2 provided with the supply holes 45 described above, it is advantageous to place the primary seal 16 without separate seal support 9 or to use a support

  of gasket 9 not having a flange surrounding the exterior

laughingly the primary seal 16.

  Figure 11 shows another example of implementation.

  tion of that of Figure 1 in which the primary seal

  36a is placed in the housing 2. The integrated sealing lip

  lower 37a is applied in a sealed manner against the envelope surface of the piston 8. The radially outer sealing lip 38a is on the other hand perpendicular to the piston 8 and bears in the end zone, in a sealed manner against a U-joint lip 35, by the front face; this seal is itself placed in the seal support 29a. The U-shaped lip seal 35 as a separate part is provided with a seal 34 applied in leaktight manner against the blind bore 5 of the housing 2. The primary seal 36a is positioned in the housing 2; the sealing lip 38a is applied against a support 32 spaced radially from the free end and extending axially from the housing 2. In order to stress the sealing lip 38a precisely in the event of depression in the pressure chamber 10, the support seal 29a is provided with a fluid channel 39 provided in the reception area of the U-shaped seal 35. A fluid channel 40 also provided in the housing 2 allows the fluid to continue to supply the pressure chamber 10 after the sealing lip 38a is raised relative to the U-shaped joint 35. FIG. 12 shows a primary seal 36b whose shape differs from that of the joint in FIG. 11; this joint

  primary is housed in a seal holder 29b. In a con-

  cordant, the radially inner sealing lip 37b is applied against the piston 8 and the radially outer sealing lip 38b is pressed frontally against the U-shaped joint 35 and on the opposite side, against the support 32. There are thus a concordance with the sealing zones according to FIG. 5 11. Between the U-shaped seal 35 and the seal support 29b there is provided a fluid channel 39 for urging the sealing lip 38b. FIG. 13 shows another variant of the seal support 29c directly receiving the seal 34

  in a peripheral groove 33; this seal ensures the sealing of the annular gap with respect to the housing 2. The realization

  and the arrangement of the sealing lips 37c,

  38c of the primary seal 36c correspond with the primary seal

  mayor of figure 12. A fluid channel 41 makes it possible to

  cite the sealing lip 38c; the route of this channel goes first frontally on the side facing the guide sleeve 6 then joins an axial segment turned towards the piston 8 and finally arrives in an outside area of the primary seal

  36c, peripherally against the sealing lip 38c.

NOMENCLATURE

  1 Master cylinder 2 Housing 3 Sniffer connection 4 Connection Blind drilling 6 Guide sleeve 7 Inner wall 8 Piston 9 Seal support Pressure chamber 11 Limit stop 12 Piston rod 13 Piston body sleeve 14a Half-shell 14b Half-shell Cavity 16a Primary seal 17 Sealing lips 18a Sealing lips 18b Sealing lip 19a Peripheral groove 19b Peripheral groove 20 Outer wall 21 Inner wall 22 Secondary seal 23 Longitudinal groove 24 Radial slot 25 Radial slot 26 Longitudinal groove 27 Segment 28 Ramp 29a Seal support 29b Seal support 29c Seal support Extension 31 Sealing rim 32 Support 33 Peripheral groove 34 Seal U-shaped lip seal 36a Primary seal 36b Primary seal 36c Primary seal 37a Lip sealing 37b Sealing lip 37c Sealing lip 38a Sealing lip 38b Sealing lip 38c L sealing channel 39 Fluid channel 40 Fluid channel 41 Fluid channel 42 Longitudinal groove 43 Bottom 44 Outer wall 45 Supply groove 46 Peripheral groove

Claims (16)

R E V E N D I C A T I O NS   1) Master cylinder for a friction clutch with hydraulic control or vehicle brake comprising a housing (2) axially sliding housing a piston (8) and U-shaped seals, with lips comprising a primary seal (16) and a seal secondary (22) sealing, the piston (8) being connected by a piston rod (12) to a pedal actuated in particular manually and the piston (8) forms on the front side, a volume pressure chamber variable (10) with the housing (2), this communicating chamber   directly with a pressure connection (4) and indirect-   with a sniffer connection (3), characterized in that a radial external sealing lip (18a, 18b) of the primary seal (16) penetrates in the mounting position in a peripheral groove (19a, 19b) of the housing (2), the width and the depth of the groove exceeding the wall thickness or a longitudinal extension of the sealing lip (18a,   18b) and the sealing lip (18a, 18b) allows the establishment   pressure in the pressure chamber (10) assu   the tightness of the pressure chamber (10) or a   munication between the pressure chamber (10) and the sniffer connection (3).   2) Master cylinder according to claim 1, characterized in that the sealing lip (18a, 18b) of the primary seal (16) has an axial length exceeding the axial length of the lip sealing (17).   3) Master cylinder according to claim 1, characterized in that during a suction of fluid in the pressure chamber (10), the sealing lip (18a, 18b) is guided against the inner wall (21) or against extensions (30) of the peripheral groove (19), these peripheral extensions, projecting and being integral with the inner wall (21). 4) Master cylinder according to claim 1, characterized in that the outer wall (20) and the extensions (30) provided between the latter and the inner wall (21) have radial slots (24, 25) distributed at the periphery in   the direction of the primary seal (16).    ) Master cylinder according to claim 4, characterized in that the outer wall (20) is in the form of a ramp at the free end, on the side of the groove, as a function of the axial length of the radial slots (24) and goes continuously decreasing   from its free end towards the bottom of the groove.   6) Master cylinder according to claim 4, characterized in that the inner wall (21) or the extension (30) has a longitudinal groove (26) continuously decreasing conically from the free end into the chamber pressure (10).   7) Master cylinder according to claim 4, characterized in that   the pressure chamber (10) has a longitudinal groove   nale (42) extending from a bottom (43) to the inner wall   lower (21) and thus with the connection (4).   8) Master cylinder according to claim 1, characterized in that an envelope surface of the seal support (9) comprises at least one longitudinal groove (23) corresponding to the slot radial (24).   9) Master cylinder according to claim 1, characterized in that the sealing lip (18b) is applied over the entire length, in the neutral state, with an envelope surface against the wall   outside (44) of the peripheral groove (19b).    ) Master cylinder according to claim 9, characterized in that   the outer wall (44) comprises, on a peripheral distribution, supply grooves (45) starting from the sniffer branch (3) and directed axially in the direction of the peripheral groove (19b).   11) Master cylinder according to claim 10, characterized in that the supply grooves (45) open into a peripheral groove (46) formed in the outer wall (44), of   axially spaced apart from the free end of the sealing lip (18b).   12) Master cylinder according to the preamble of claim 1, characterized by an outer radial sealing lip (38a-38c) of the seal   primer (36a-36c) is applied frontally against the support   seal port (29c) or a U-shaped lip seal (35) placed in the seal support (29a, 29b) with a support (32) provided on   the housing (2), on the opposite side, offset radially with respect to   port at the free end, the sealing lip (38a-38c) allowing, depending on a pressure being established in the   pressure chamber (10), ensuring the tightness of the chamber   pressure bre (10) or to allow the communication of the fluid between the pressure chamber (10) and the connection of sniffer (3).   13) Master cylinder according to claim 12, characterized in that   the annular support (32) is provided with radial channels (40) which repair tis on the outskirts.   14) Master cylinder according to claim 12, characterized in that   the seal support (29c) or a U-shaped lip seal (35)   in the joint support (29a, 29b) is sealed by   connection to the housing using a seal (34).   15) Master cylinder according to claim 12, characterized by a fluid channel (39, 41) provided in the seal support (29a-29c) this channel having a trace partially surrounding the outer contour of the U-seal (35) or the primary seal (36c).   16) Master cylinder according to claim 12, characterized in that the sealing lip (38c) has a bead   seal (31) applied against the seal support (29c).   17) Master cylinder according to claim 14, characterized in that   the seal (34) is placed in a U-shaped lip seal (35) tinct.   18) Master cylinder according to claim 12, characterized in that the sealing lip (38a, 38b) is applied so   watertight against the front face of the U-ring (35).   19) Master cylinder according to claim 12, characterized in that the primary seal (36c) is placed in the seal holder (29c).