FR2459164A1 - DOUBLE-LINE DOUBLE LINE MASTER CYLINDER - Google Patents

Abstract

THE INVENTION RELATES TO A DOUBLE IN-LINE MASTER CYLINDER. IT RELATES TO A DOUBLE INLINE MASTER CYLINDER HAVING A PRIMARY PISTON 32 AND A SECONDARY PISTON 70. ACCORDING TO THE INVENTION, THE PRIMARY PISTON HAS A PRIMARY SEAL 34 AND A SECONDARY SEAL 36 FOR SEALING, AND THE SECONDARY SEAL IS LUBRICATED. BY FLUID COMING THROUGH A PASSAGE 56 SHAPED IN THE PRIMARY PISTON, FROM FLUID TANK 20. IN THIS WAY THE PRIMARY PISTON CANNOT SCRATCH THE MASTER CYLINDER BORE SURFACE. APPLICATION TO MOTOR VEHICLE BRAKING CIRCUITS.

Description

The present invention relates to a master

  double cylinder in line of small size.

  The current trend towards realizing

  Small and light automotive vehicles required efforts to reduce the size and weight of many vehicle components. For example, there have been proposed small in-line master cylinders of small size, having a length and so

  reduced weight, but generally requiring

  the secondary seal of the primary piston. The classic in-line dual master cylinder shown in the US patent

  No. 3,147,596 to an assembly comprising a primary piston

  mayor carrying a primary seal under pressure and a secondary seal that is not subject to pressure. The latter is important because it prevents

  leakage of brake fluid to the outside of the master

  cylinder when the primary seal which is under

  leakage or oozing. So,

  these double master cylinders in line of low

  not having a secondary piston seal

  primary education are not desirable because they can

  experience brake fluid leakage to the outside

  which can finally empty the tank and

  void the introduction of air into the braking circuit

  swims so well that the possibilities of circuit failure

braking are increased.

  The invention relates to a small in-line double master cylinder, whose length and

  weight is low compared to the double master cylinder

  conventional type of line described in the aforementioned patent, but which preserves the secondary seal of the

primary piston.

  The in-line dual master cylinder comprises a housing having a bore, a fluid reservoir having first and second sealed compartments, and a primary piston and a secondary piston disposed in a housing.

  bore and delineating primary and secondary chambers

  condensate containing fluid. The primary and secondary pistons are movable in the bore and ensure the application of a pressure to the fluids of the

  primary chamber and the secondary chamber

  tively. The primary piston has a rod having an orifice for communicating between the first compartment of the reservoir and the primary chamber. The

  secondary piston has a stem having a hole

  both the communication between the second compartment of the tank and the secondary chamber. The primary piston

  carries a first and a second joint at a distance of

  external riphery and sustainable cooperation

  with the wall of the bore on which they slide.

  Passages formed in the primary piston provide communication between the first chamber of the reservoir and the portion of the outer periphery of the primary piston which is between the first and

the second seal.

  Other features and advantages of the invention will be better understood when reading the

  following description of examples of realization

  and with reference to the accompanying drawing in which the single figure is a longitudinal section of a master cylinder

double line according to the invention.

  An advantageous embodiment of master

  In-line double cylinder according to the invention is generally referred to as 10 and includes a housing 12 having a reservoir 14 and a bore 16. The reservoir 14 is

  divided by a partition 18 into two separate compartments

  20, 22. Holes 24 and 26 are formed in the casing 12 and respectively connect the compartments and 22 to the bore 16. Exit holes 28, 30

  formed in the housing 12 and intersect the

  16. A cover not shown is placed at the

  upper part of the tank 14.

  A primary piston 32 can move in the bore 16. It carries a primary seal 34 and a

  secondary seal 36 intended to cooperate in an

  with the annular wall of the bore 16 along which they slide. The primary piston 32 has annular surfaces 38, 40, 42, 44 adjacent the primary and secondary seals 34, 36. A cavity 46 is formed in the front portion of the primary piston 32 and an annular groove 48 is formed in the cavity 46. Passages 50, 52 are formed in the front portion of the primary piston 32 and intersect the cavity 46. A blind bore 54 penetrates to the rear portion of the primary piston 32 from the inner end surface 47 of the cavity 46. passage 56 is formed in the rear portion of the primary piston 32 between the bore 54 which it intersects and the annular surface 42. A rod 58 has a first end screwed into the bore 54 so that it moves with the primary piston 32. A seal 60 is placed between the rod 58 and the wall of the bore 54. The rod 58 has a longitudinal passage 62 which passes through it and a transverse hole 64 which intersects the passage 62. An annular shoulder 66 is delimited at the end.

  free of the rod 58. An elastic ring 68 is placed

  in a groove in the open end of the

  wise 16 so that it limits the displacement of the piston

primary 32 to the left.

  A secondary piston 70 can move in the bore 16. This secondary piston 70 carries a sealing member 72 intended to cooperate sealingly with the annular wall of the bore 16 along which it slides. A cavity 74 is formed in the front portion of the secondary piston 70 and an annular groove 76 is formed in the cavity 74. A blind hole 78 is disposed in the rear portion

  of the secondary piston 70 from the surface of the

  internal cavity 75 of the cavity 74. A cavity 80 and passages 82, 84 are formed in the rear portion of the secondary piston 70. A rod 86 has a first end screwed into the bore 78 so that it moves with the secondary piston 70. A seal 88 is placed between the rod 86 and the wall of the bore 78. The rod 86 has a longitudinal passage 90 which passes through it and a transverse hole 92 which intersects the passage 90. An annular shoulder 94 is delimited at free end of the rod 86. A screw 96 is screwed to the bottom of the casing 12 and its end penetrates into the bore 16 so that it prevents a greater displacement to the left of the secondary piston

  70. A seal 98 is placed between the screw 96 and the housing

tier 12.

  A guide member 100 is intended to telescopically accommodate the rod 58. This member 100 has a central cavity 102, an end wall 104 pierced with a hole 105, an annular shoulder 106 and an annular flange 108. carries a sealing member 110 which cooperates sealingly with the outer peripheral surface of the rod 58 along

  from which he can slide. A cup 112 of ethanol

  The gap is placed close to the annular flange 108 of the guide member 100. The outer periphery of the cup 112 has an annular lip 114 intended to cooperate sealingly with the annular wall of the bore 16 on which it can slide. The guiding member 1.00 is housed in a central hole 116 of the cup 112 with which it co-operates with

  waterproof. A return spring 118 is surrounded and

  awarded by the guide member 100 and the primary piston

  mayor 32 and it normally pushes the primary piston 32 and the rod 58 to the left in the figure so well

  that the primary piston 32 cooperates with the elastic ring

  68, the spring also normally pushing the sealing cup 112 and the guide member 100 to the right in the figure, in cooperation with the secondary piston 70. A first end of the return spring 118 cooperates with a plate 120 of detention

  placed near the cup 112 while the other end

  spring 118 is housed in the annular groove 48 formed in the primary piston 32. A guide member 122 is intended to house

  telescopically the rod 86. This organ 122 has a

  central cavity 124, an end wall 126 pierced with a hole 127, an annular shoulder 128 and a flange

  annular 130. the organ 122 carries a body 132 of

  which co-operates tightly with the surface

  outer riphenic rod 86 and can slide along this surface. A sealing cup 134 is placed near the annular flange 130 of the guide member 122. The outer periphery of this cup

  134 has an annular lip 136 for cooperating with

  leak tightly with the annular wall of the

  16. The guide member 122 is housed in a hole

  central 138 of the cup 134 with which it cooperates

  father tightly. A support plate 140 is housed in the closed end of the bore 16. A return spring 142 is surrounded and compressed between the guide member 122 and the secondary piston 70 and it normally pushes the secondary piston 70 and the rod 86 to the left in the figure so that the piston cooperates with the guide member 100; the spring

  also normally pushes the cup 134 of

  stillness and the guide member 122 to the right on

  the figure, in cooperation with the support plate 140.

  A first end of the cooldown spring 142

  father with a retaining plate 144 which is placed near the sealing cup 134, the other end of the spring 142 being housed in the annular groove 76

of the secondary piston 70.

  In the double in-line master cylinder, a primary chamber 146 is formed in the bore 16

  between the primary piston 32 and the cup 112 of

  and a secondary chamber 148 is formed in

  the bore 16 between the secondary piston 70 and the neck

  excavator 134 sealing. When the master cylinder is in the fully released position shown in the figure, the compartment 20 of the tank communicates with the primary chamber 146 through the hole 64 formed in the rod 58, and the compartment 22 of the tank

  communicates with Secondary Chamber 148 through

  median of the hole 92 of the stem 86 so that the di-

  latation and contraction of the fluid, due to varia-

  temperatures, can be compensated.

  We now consider the operation of the master cylinder according to the invention. The in-line dual master cylinder is controlled when a force F is applied to the left end of the primary piston 32 and moves the latter and the rod 58 to the right in the figure. This displacement to the right of the rod 58 causes the passage of the hole 64 beyond the sealing member 110 carried by the body 100 of

  guidance, so that communication between the

  20 tank and the primary chamber 146

  is interrupted. Moving to the right of the pis-

  your primary 32 also causes the compression of the

  118 and raises the fluid pressure of the chamber

  primary 146 so that the fluid is transmitted through the exit hole 28 to a first portion of a

  dual braking circuit (not shown). The pressure

  sion established in the fluid of the primary chamber 146 and the force applied by the compressed spring 118

  exert a force at the left end of the piston

  70 so that it moves to the right with the rod 86. This movement to the right of the rod 86 passes the hole 92 beyond the sealing member 132 carried by the guide member 122 if although the compartment 22 of the tank no longer communicates with the secondary chamber 148, approximately at the same time as the communication between the

  compartment 20 and the primary chamber 146 is

  broken. The displacement to the right of the piston

  70 raises the fluid pressure of the secondary chamber 148, and this fluid is transmitted through the exit hole to the other portion of the dual braking circuit (not shown), substantially at the same time as the pressurized fluid is transmitted. to the circuit connected to the exit hole 28. When the primary piston 32 continues to move to the right, the fluid pressure of the primary chamber 146 increases and exerts a force on the secondary piston 70 so that the latter moves to the right and raises and maintains

  a virtually equal pressure of the fluid in the chamber

secondary school 148.

  When the force F applied to the primary piston

  32 is removed, the recoil springs 118, 142 de-

  place the primary 32 and secondary piston 70 to the left until the primary piston 32 cooperates

  with the elastic ring 68. The displacement towards the left

  both pistons 32, 70 can create a depression in the chambers 146, 148. The pressure difference

  corresponding to this depression causes circula-

  fluid of the compartments 20, 22 of the reservoir to the bore 16 through the inlet holes 24, 26 and

  at the level of the annular lips 114, 136 of the

  shovels 112, 134, to the chambers 146, 148 of fluid so that any lack of fluid in these chambers is removed. When the double inline master cylinder returns to the fully free position shown, communication is again established between the tank compartments 20, 22 and the fluid chambers 146, 148 through the

holes 64 and 92.

  When the brake circuit connected to the exit hole 28 leaks, the force F which is applied causes the displacement of the primary piston 32 and the rod 58 to the right, with compression of the spring 118, but the displacement to the right of the primary piston 32 does not increase the pressure of the fluid in the primary chamber 146. The force applied by the compressed spring 118 causes the displacement of the secondary piston 70 and the rod 86 to the right so that the compartment 22 of the reservoir and the

  Secondary Chamber 148 no longer communicate as

  previously written. The force F which is applied displaces

  this the primary piston 32 to the right until the inner end surface 47 of the cavity 46 abuts against the end wall 104 of the organ

  guidance. This cooperation by contact with

  tone 32 and the organ 100 causes the application

  Direct contact of the force F with the secondary piston 70 to the right so that the pressure of the fluid of the secondary chamber 148, transmitted through the exit hole 30 to the corresponding portion of the circuit, rises. When the circuit connected to the exit hole 30

  shows a leak, the force F which is applied de-

  places the primary piston 32 and the rod 58 to the right and causes compression of the spring 118 so that the communication between the reservoir compartment 20 and the primary chamber 146 is interrupted as previously described, and the fluid pressure of the primary chamber 146, transmitted through the exit hole 28 to the corresponding portion of the circuit, rises. This high pressure prevailing in the primary chamber 146

  and the force applied by the compressed spring 118

  note the application of a force to the secondary piston which moves to the right but, given the leakage, this displacement to the right of the piston 70 does not cause the increase of the pressure of the fluid of the secondary chamber 148. In Accordingly, the secondary piston 70 moves to the right until the inner end surface 75 of the cavity 74

  abut against the end wall 126 of the or-

  guide 122. This cooperation by contact of the piston 70 and the member 122 prevents any displacement

  further to the right of the piston 70 which

  then titrates a fixed end of the primary chamber 146 to the right, the primary piston 32 continuing to fix the pressure of the fluid in the primary chamber 146.

  An important characteristic of the master

  double cylinder in line 10 according to the invention is con-

  staggered by the passage 56 formed in the rear part

  of the primary piston 32, between the piercing 54 that it

  section and the annular surface 42. A function of this passage 56 is to allow the fluid of the compartment 20

  of the tank to constantly lubricate the annu-

  40 of the primary piston and thus prevent scoring of the annular wall of the bore 16 during displacement of the primary piston 32. Scoring of the bore 16 is undesirable because it can cause deterioration of the seals 34, 36 and leaks of fluid at these joints. Fluid leakage past the primary seal 34 may cause a brake failure, preventing a sufficient increase in fluid pressure in the primary chamber 146 by

  the primary piston 32 for the brakes to work.

  Fluid leakage beyond secondary seal 36

  can finally exhaust the fluid reserve of the com-

  part of the tank and may cause the introduction

  air duction in the braking circuit so that

  the possibilities of brake failure are increased.

  It appears that the bore 16 is not scratched by the

  annular surfaces 42, 44 of the primary piston because

  indicated in the figure, there is no sliding contact

  With the annular wall of the bore 16, another function of the passage 56 is to allow the return to the compartment 20 of the reservoir of the fluid which may have

  seeps or leaks beyond the primary seal 34.

  The invention therefore relates to a master cylinder

  in line, the length and weight of which are

  significantly lower than those of a typical in-line double master cylinder as described in the aforementioned U.S. Patent No. 3,147,596, the master cylinder according to the invention retaining the

  secondary safety seal placed on the primary piston

  mayor as well as the compensation of the dilation and the contraction of the fluid by setting in communication

  tank and pressurized chambers.

  Of course, various modifications can be made by those skilled in the art to the devices

  which have just been described as examples only

  non-limiting plies without departing from the scope of the invention.

Claims (3)

  1. Double master cylinder in line of small size, of the type which comprises a casing having   a bore, a fluid reservoir, primary pistons   may and secondary located in the bore and defining primary and secondary chambers in this bore, the primary and secondary pistons being movable in the bore so that they raise the   fluid pressure in the primary and secondary chambers   condenser, the primary piston having a primary seal at its periphery for sealingly engaging the wall of the bore along which it slides, the primary piston further comprising a   rod having a device for communicating with   the primary chamber and the fluid reservoir, the   said master cylinder being characterized in that the piston   your primary (32) has a secondary seal <36) remote from the primary seal (34), and the master cylinder comprises   a device (56) for lubricating the secondary seal   re (36), allowing communication between the region (42) of the seal and the communication device (62, 64) formed in the rod (58).   2. master cylinder according to claim 1, characterized in that the lubricating device comprises a passage (56) formed in the primary piston (32) and disposed between a blind hole (54) and the region (42) of the joint.   3. master cylinder according to claim 2, characterized in that the region (42) of the seal is delimited by an annular cavity of the primary piston,   disposed in the space between the primary seals Mayor and secondary.