FR2521509A1 - BRAKE FORCE REGULATOR FOR A HYDRAULIC BRAKE SYSTEM FOR A VEHICLE - Google Patents

Abstract

INVENTION RELATING TO THE BRAKING OF VEHICLES. AN EQUALIZING PISTON 52 IS PROVIDED BETWEEN TWO OUTPUT CHAMBERS 30, 42 EACH CONNECTED TO AN RZI OR RZII BRAKE CYLINDER OF A REAR WHEEL. A FIRST INLET CHAMBER 26 IS PROVIDED IN A MIDDLE REGION OF THIS PISTON, CONNECTED TO A FIRST MAIN CYLINDER HZI AND, BY A FIRST VALVE 86, 88, TO THE FIRST OUTLET CHAMBER 30. THE SAID VALVE IS PROVIDED IN A FIRST PISTON AT GRADIN 64 LOCATED INSIDE PISTON 52; IT CLOSES WHEN THE PRESSURE IN THE FIRST CHAMBER 30 EXCEEDS A DETERMINED QUANTITY. A SECOND INPUT CHAMBER 38 IS CONNECTED TO A SECOND HZII MAIN CYLINDER AND, BY A SECOND VALVE 104, 106, CONTROLLED FOLLOWING THE SLOWING DOWN OF THE VEHICLE, TO THE SECOND OUTLET CHAMBER 42. APPLICATION TO THE SIMBRATION OF REGULATORS AND REGULATORS. .

Description

The present invention concerning braking

  vehicles, is more specifically related to a

  brake force regulator for a hydraulic brake installation for a vehicle having a casing body and wherein: a first inlet chamber and a second inlet chamber and a first outlet chamber and a second outlet chamber are established respectively for a first brake circuit and a second brake circuit; the two exit chambers are separated from each other by an equalizing piston; between the first inlet and outlet chambers there is arranged a stepped piston which delimits by its largest front side the first outlet chamber and is biased by a spring in the direction of a decrease of this outlet chamber; in addition, between the first entrance and

  outlet there is arranged a valve controlled by the posi-

  tion of the pressure sensitive stepped piston, relative to

  to the equalizing piston; and between the second entrance and exit rooms there

  another controlled valve is arranged.

  Brake force regulators of this kind are provided especially for diagonally shared vehicle brake installations, in which the two brake circuits are each connected with a front wheel and the rear wheel opposite it diagonally.

  such brake installations for vehicles the regular

  The force of the brake force has the effect of reducing the increase

  pressure on the rear wheel brakes by

  increased pressure on the front wheel brakes, as soon as the pressure on the rear wheel brakes reaches a specified value and

  possibly the vehicle experiences a slowdown

  completed. In a known brake force regulator of the kind described (German Patent Publication No. 28 20 768),

  the stepped piston is axially disposed at the end of the piston

  The two pistons are hollow and contain

  each valve body and a spring which urges the corresponding valve body towards

  a valve seat formed in the piston concerned.

  -The two valve bodies each have an extension

  axially extending outwardly In the position of rest, the valve body arranged in the

  step piston is supported by its extension on the piston

  In the rest position the two valves are kept open, so that the first inlet chamber is connected through the piston

  step in the first exit chamber and that the denial

  my entrance chamber is connected through the piston of equal

  second chamber of exit In addition, the second

  x input chamber is connected to the second exit chamber through channels that bypass the

  valve arranged in the equalizing piston and which

  hold a valve controlled following the slowdown.

  The valve depending on the slowing down is constituted by a ball that can move in a hole made in

  the body envelopes and shifted in the axial direction by

  two pistons and a valve seat which is

  in a plug closing this piercing.

  With this known brake force regulator,

  when during braking the pressure in the first

  outlet chamber exceeds a certain value, the piston

  your-stepped moves contrary to the strength of the res-

  aort which solicits him in the direction of the piston of equali-

  sation by deviating and tending to increase the

  volume of the first outlet chamber

  lisation follows the step piston and thereby maintains

  the pressure balance between the two exit chambers.

  As a result of the displacement of the equalizing piston, the piston

  your tone in it closes, so the pressure

  sion can still ascend to the second chamber of

  under the condition that the valve depends on

  When the stepped piston continues to move, the valve that is

  it then closes as well and subsequently the

  in both outlet chambers can still rise in a reduced ratio compared to the pressure in the two inlet chambers, which depends on the ratio of

  surfaces of both sides of the stepped piston.

  If the first brake circuit of the vehicle brake system, associated with the known brake force regulator, fails to operate, the equalizing piston operates without participation of the stepped piston, in contrast to the spring urging the stepped piston ; consequently it appears a pressure limitation

  in the second exit chamber only for a

  for which we must already expect a blocking of the rear wheel connected to the second brake circuit On the other hand, if the second brake circuit does not work, the valve contained in the step piston closes prematurely because the equalization piston no longer follows in this case the piston As a result the pressure in the first outlet chamber is prematurely reduced

  in the first exit chamber relative to the pres-

  in the first entrance chamber, which is also

  undesirable, because of this braking of the rear wheel associated with the first brake circuit still

  intact is lower than in the normal state of both

  The invention has the object, in a regulator of

  brake force of the kind described in the introduction, of

  the effect of the failure of a brake circuit on the

  pressure in the outlet chamber of the other brake circuit and establish a brake force regulator in a simpler form and in a

save space.

  This result is obtained according to the invention

  thanks to the fact that the step piston is arranged,

  jointly with the requesting and sponsoring

  pressure-sensitive poppet in the equalizing piston and that the pressure sensitive valve is controlled by the stepped piston regardless of the position of the piston

  of equalization relative to the envelope body.

  Thus the brake force regulator according to the invention contains only a pressure sensitive valve and this is arranged together with the stepped piston from which it is controlled, inside the equalizing piston, saving The effect of this valve is independent of everything

  movement of the equalizing piston relative to the body

  develops; as a result, this pressure-dependent valve operates the switching, as long as the first brake circuit

  is intact, still for the same pressure, as the second

  the braking circuit is also intact or not.

  The second brake circuit contains only the additional valve ordered; therefore it is excluded that after closing of this valve the pressure in the

  second exit chamber still stands without reduction.

  The equalizing piston is usefully disposed between two equal springs supported in the casing body

  and having a flat characteristic.

  A preferred embodiment of the invention is established on the characteristic of the force regulator

  known brake of this kind, namely that the additional valve

  is ordered according to the slowdown A

  In this respect, according to the invention, it is

  be the two entry and exit chambers and following the

  m axis as that of the equalizing piston and while still

  to move independently of him, a second piston

  step, which has, at its smallest front-end

  the second inlet chamber, a valve seat of the valve depending on the retardation and which takes, in the idle state, a stop position in which the

  second entrance room has its smallest volume.

  As a result, the additional advantage is obtained that the valve depends on the retardation and is arranged

  in the second brake circuit does not work

  me pressure relief valve but as a pressure reducing valve and so far it can be

  compared to the pressure sensitive valve that

  due to the first brake circuit After closing the two valves the equalization piston would actually cause equalization of pressure between the two outlet chambers also when only the pressure-dependent valve was only established as a pressure-reducing valve and on the other hand the dependent valve

  slowing down as a pressure limiting valve

  if we; the construction of the two valves in the form of

  However, the pressure reducing valve has the advantage

  after the two valves have been closed, it is possible

  to have a pressure equalization between the two

  exit chambers without displacement of the equalizing piston

  or with very little movement of it.

  The invention will be better explained and understood by the following description of two embodiments, given by way of nonlimiting reference to the accompanying diagrammatic drawings, among which:

  FIG. 1 is an axial section of a regulator

  of brake force according to the invention and FIG. 2, an axial section of a regulator of

  modified brake force compared to that of Figure 1.

  The brake force regulator shown on

  FIG. 1 comprises a steel casing body 10

  the single rectangular cross section, comprising a graded drilling whose axis is referred to in the following as the longitudinal axis 12 The regulator of

  brake force is provided so that it can be fixed in a

  motor vehicle so that the longitudinal axis 12 is

  in a vertical longitudinal plane of the vehicle, about 30 degrees to the horizontal, and arranged so that the end of the casing body on the left in FIG. 1 is placed in front of and higher than the rear end, right For the corresponding attachment there is provided a bolt, not shown, which passes through a hole

  transverse 14 in the envelope body 10.

  The stepped bore is machined along the longitudinal axis 12 from the front in the casing body 10 and is constituted by a threaded portion before 18,

  closed by a screw cap 16, by a cylindrical part

  20-degree front connector, whose diameter is only

  slightly smaller than the inner diameter of

  the threaded portion 18, and a cylindrical portion

  no 22 of average diameter and a rear cylindrical part

24 of small diameter.

  The middle region of the front cylindrical portion constitutes a first inlet chamber 26 which can

  be connected, via a cylinder connection

  28, to a first main cylinder Hz I, in-

  The region in front of the front cylindrical portion 20 forms a first outlet chamber 30 which can be connected via a brake connection 32 to a first wheel brake cylinder RZ I, also indicated by an arrow. only by an arrow and mounted on a rear wheel In the vicinity of the rear end of the cylindrical portion before 20 there is provided a chamber

  aeration 34 which is connected to the atmosphere via

  of a dust filter 36.

    the rear end of the rear cylindrical portion 24 is formed a second inlet chamber 38 which can be connected, via a second main cylinder connection 40, to a second cylinder

  the main Hz II, again indicated only by a

  In addition, the front end of the middle cylindrical part 22, together with the rear end of the front cylindrical part 20, forms a second chamber of

  output which can be connected via a

  x brake connection 44, to a second wheel cylinder Rz II, also indicated by an arrow, for the second

rear wheel of the vehicle.

  In the cylindrical part before two weak

  springs 46 and 48 are arranged, the front spring

  against the plug 16 and the rear spring against

  a perforated plate 50 disposed between the cylindrical parts

  20 and 22 between the two springs 46 and 48 there is arranged an equalizing piston 52 low prestressing

  The two springs 46 and 48 are, for example,

  in the form of cruciform leaf springs with

  riser force-path rising in a flat way; this means

  that, for axial deviations from the equalizing piston,

  52 arranged floating between the springs, these

  exert only very weak forces of recall, just-

  to bring it back after each brake application

  in its average position represented.

  The equalizing piston 52 comprises, on its surface

  this outer delimitation, three annular seals 54, 56 and 58, which separate the first inlet chamber 26 of the first outlet chamber 30 and the ventilation chamber 34 as well as these of the second chamber

  The equalizing piston 52 is hollow and

  a sheath 60 attached to its front end and

  The drilling 62 guides a first stepped piston 64 through its front portion in which it has its largest diameter. In the rear, closed rearward portion, the equalizing piston 52 is provided with a hole 66. which has a smaller diameter

  that the bore 62 and houses a corresponding rear portion

  Step piston 64 The step piston 64 is connected to

  sealed to the two holes 62 and 66 respectively.

  by one of the annular seals 68 and 70; furthermore, the sleeve 60 is sealingly connected to the equalizing piston 52 by an annular seal 80. The region of the bore 66 lying behind the annular seal 70 is connected to the atmosphere via the chamber

aeration 34 and the filter 36.

  Inside the equalizing piston 52 is disposed, around the first step piston 64, a spring

  of helical compression 82, conical at the front and cylindrical

  drique then, which is supported by its rear end on the equalizing piston 52 and by its end

  before on the step piston 64 and tends to maintain.

  this applied against a front wall 76 of the sleeve 60 A at the front end of the stepped piston 64 there is fixed an annular valve seat 86 in

  elastomer which together with a body of

  guided poppet 88 with possibility of axial sliding in the step piston 64, a valve or valve 86, 88

  pressure sensitive The valve body 88 is pre-

  constrained forward by a helical compression spring 90 disposed within the stepped piston 64 and

  has a protrusion before 92 which rests, in the position

  resting movement shown against the front end wall 84 and holding the valve body 88 lifted by

relative to the valve seat 86.

  In the middle cylindrical portion 82 and in the rear cylindrical portion 84 a second stepped piston 94 is provided and each has a sealed annular seal 96, 98. The front front side 100 of the second stepped piston 94 delimits, together with the equalizing piston 52, the second exit chamber

  42 The front-end 102, which has a smaller superstructure

  face that the frontal front tee 100, delimits the second inlet chamber 38; this rear end face 102 is fixed with an annular valve seat 104 made of elastomer which, together with a valve body 106, forms a valve 104 e which depends on the retardation. The valve body 106 is constituted, in the example according to figure

  1, by a ball that is guided so that it can be

  place axially in a cage 108 attached to the second piston

stepped tone 94.

  The second step piston 94 has an axial passage channel 110 which opens into the seat

  valve 104 and contains a rod 112

  against the perforated plate 50 and just do not touch

  the valve seat 104, when the second piston to

  din 94 is in its represented rest position, in which it bears against an annular shoulder 114 situated between the cylindrical portions 22 and 24 Par-

  both of the shoulder 114, a discharge bore 116 results in

tit on the outside.

  In the following description of the operating mode

  of the brake force regulator shown in

  Figure 1 it will first be admitted that the two cir-

  brakes Hz I-Rz I and Hz II-Rz II are in a normal state

  When the two main cylinders Hz I and Hz II (which are usually arranged in a common box) are actuated, the pressure sensitive valve 86, 88 and the valve 104, are applied. depending on the slowdown are both open The pressure is gradually increasing in

  entry chambers 26 and 28 is therefore

  without weakening at exit chambers 30 and 42.

  During a determined pressure increase, the vehicle undergoes a slowdown which causes the valve body 106 to travel upwards and forwards

  of ball, inside the cage 108 and the wall lamp

  be the valve seat 104, so that the valve 104,

  106 depending on the slowdown is closing The characteristic

  that spring 82 is selected such that the pressure increase thus far obtained in the outlet chamber 30 moves the step piston 64 rearward until the valve seat 86 bears against the body of the valve 88 and consequently closes the valve 86, 88 sensitive to pressure, if the vehicle is not loaded, substantially

  in that the valve 104, 106 depending on the

  If one of the two valves were to close before the other a displacement of the equalizing piston 52 emp 8 would then that in the two outlet chambers 30 and 42 there will not occur a pressure difference * When the pressure continues to grow in

  two inlet chambers 26 and 38, the valve 86, 88, de-

  during pressure, works in association with

  the first step piston 64 as a reduction valve

  pressure which would only increase the pressure in the outlet chamber 30 by an amount which would be reduced in relation to the increase in pressure

  in the entrance chamber 28, in the ratio of

  these acting front ends of the first step piston 64.

  In a similar way, the valve depends on the slowdown.

  104, 106 operates in conjunction with the second

  piston 94, as a reduction valve of

  pressure which allows the pressure to increase in the

  xth exit chamber 42 than an amount that is re-

  duit against the pressure in the second chamber

  input 38 in the ratio of the front surfaces

  100 and 102 of the second stepped piston 94.

  With a heavily loaded vehicle, the increase

  The pressure in the outlet chambers 30 and 42, for which the first stepped piston 64 is rearwardly shifted and closes the pressure sensitive valve 86, 88, still can not slow down the vehicle so much.

  that the valve 104, 106 depending on the slowdown will be

  As a result the pressure continues to croltre, the second main cylinder Hz II is transmitted without

  weakening at the exit chamber 42 and displacing it

  The result of the equalizing piston 52 forwards is to increase the pressure in the outlet chamber 30 by the same amount as in the outlet chamber 42.

  two wheel brake cylinders Rz I and Rz II are therefore

  pressure continues to grow until finally we reach a slowing down of the vehicle

  for which the valve 104, 106 depends on the slowing down

  It is closed and allows a further growth of the pressure in the outlet chamber 42 and, because of the mobility of the equalizing piston 52 also entering the outlet chamber 30, with a reduced growth rate compared to the continuation. of the growth of it the pressure in the entrance chambers 26 and 38 is

  If the first brake circuit Hz I-Rz I / fails

  lant, the equalizing piston 52 comes to each action

  of the brake in its front end position, fixed by the plug 16, so that the outlet chamber 42 absorbs more brake fluid and the

  driver becomes aware of the failure of the first

  baked by the lengthening of the running of the pedal

  The brake valve 104, 106 depending on the slowing down

  during the downturn resulting from the reorganization

  setting the angle of inclination of the longitudinal axis 12

  on the horizontal The second step piston 94 is de-

  however, when the pressure continues to grow faster in the inlet chamber 38 than with the first intact brake circuit I-RZ I and therefore the shaft 112 raises the valve body 106 relative to the valve seat 104, so that the pressure in the outlet chamber 42 is again equalized to that in

  the inlet chamber 38 and the rear wheel, corresponding to

  to the wheel brake cylinder Rz II, is therefore

  this more strongly braked than with the first circuit of

brake intact.

  If, on the other hand, the second Hz II-Rz II brake circuit fails, the equalizing piston 52 moves during each braking to come to its rear end position, to the right on the drawing, which is fixed by the perforated plate 50; the valve 86, 88 depending on the pressure, however, operates in a normal manner. The modified brake force regulator, which is shown in FIG. 2, differs from that according to the

  Figure 1 only by features of its region ar-

  which is to the right of the perforated plate 50.

  The cylinder portion 22 extends here further to the

  and from the rear a bushing 118 is sealingly secured in the casing body 10, the inner diameter of which is smaller than that of the cylinder portion 22 In the cylinder part 22 and in the sleeve 118 a stepped piston 120 is guided; this one concords, for the conformation and the dimensions,

  with the stepped piston 64 While the piston with

  din 64 according to Figure 2 shows, as in Figure 1, a connection, controlled by the valve 86, 88 depending on the pressure, between the first inlet chamber 26 and the first outlet chamber 30, the step piston 120 constitutes a link controlled by a dependent valve

  of the pressure 122, 124 between the second chamber of

  The valve 122, 124 includes an annular valve seat 122 and attached to the forward end of the stepped piston 120 and a valve body.

  valve 124, sliding axially, is guided in the pis-

  stepped tone 120 which is biased by a spring 126

  also disposed in the piston 120, towards the seat

  valve 122 and having a projection before 128.

  In the rest position represented projection 128 is

  against the perforated plate 50, so that it

  holds the valve body 124 spaced from the valve seat 122. At the rear end of the casing body 10 is

  mounted, resting on a bearing bolt 130, perpendicular to

  and at a certain distance from the longitudinal axis 12, a lever 132 at the end of which is hung a spring indicated by an arrow 134 The spring 134 is attached in a known manner to an axis of the corresponding vehicle so

  that the lever 132 shifts in the direction of the arrow

When the load increases In the lever 132, a set screw 136 is screwed substantially along the longitudinal axis 12 and is fixed by a locknut 138 The adjusting screw 136 is sealingly connected by means of a sheath 140 to the casing body 10 and to the sleeve 118 and is applied at its end to the rear end surface of the step piston 120. The lever 132 and hence also the adjusting screw 136 are represented

  in a position corresponding to a low load of

  vehicle. When, during braking, the pressure rises only moderately in the second inlet chamber 38 (in the same way as in the first inlet chamber 26), it is transmitted by the open valve 122, 124 to the second chamber If the pressure in the outlet chamber 42 exceeds a predetermined value by the adjustment of the spring 134, the stepped piston 120 is then moved to the right in FIG. 2, thus towards the rear, against resistance

  spring 134, by the differential force which is im-

  awarded, so that the valve seat 122 is pressed against the valve body 124 and the communication is interrupted between the second inlet chamber 38 and

  the second exit chamber 42 When the pressure

  continues to grow in the inlet chamber 38, the piston

  step 120 moves a little further forward,

  that the valve 122, 124 is temporarily open and that the pressure increases in the outlet chamber 42, as the pressure increases in the chamber 38, in a ratio corresponding to that of the front surfaces

acting on the step piston 120.

  But if the vehicle is more heavily loaded and therefore the spring 134 is more heavily loaded, it keeps the lever 132 in a position which

  rotated, relative to that shown, by a few

  clockwise

  the step piston 120 takes, if the brake is not ac-

  a starting position slightly shifted forwards with respect to the position shown, ie in FIG. 2 to the left. If braking is then applied and the pressure increases in the inlet chamber 38 and in the outlet chamber 42, all that is required is a slightly greater pressure increase to shift the step piston 120 rearward until the valve seat 122 reaches the valve body 124. thus closes, for a rather heavy load of the vehicle, only when a higher pressure is reached in the outlet chamber 42 The valve 122,

  124 is therefore a valve depending on the load of the vehicle.

  which replaces the valve 104, 106 depending on the

  vehicle and shown in Figure 1.

Claims (3)

  1 Brake force regulator for an actuator   hydraulic brake installation for vehicle comprising.   an envelope body (10) and wherein: a first inlet chamber and a second inlet chamber (26, 28) and a first sartie chamber and a second outlet chamber (30, 42) are respectively established for a first brake circuit and a second brake circuit (Hz I Rz I and Hz II Rz II);   the two exit chambers (30, 42) are separated   trimmed with each other by an equalizing piston (52); between the first inlet and outlet chambers (26, 30) there is arranged a stepped piston (64) which delimits the first outlet chamber (30) with its largest front end and is urged by a spring ( 82) in the direction of a decrease of this outlet chamber (30);   In addition, between the first chambers of   and outlet (26, 30) there is arranged a valve (86, 88) controlled by the position of the stepped piston (64)   pressure sensitive relative to the equalizing piston   tion (52); and between the second chambers of entry and   outlet (38, 42) another control valve is   (104, 106), said regulator being characterized in that the stepped piston (64) is arranged, together with the biasing spring (82) and the pressure sensitive valve (86, 88), in the piston equalization (52) and in that   that the pressure sensitive valve (86, 88) is controlled   from the step piston (64) regardless of the posi-   of the equalizing piston (52) relative to the body envelope (10).   Regulator according to claim 1, characterized   characterized in that the equalizing piston (52) is disposed between two equal springs (46, 48) supported in the body   casing (10) and having a flat characteristic.   3 controller according to claim 1 or 2, wherein the valve disposed between the two inlet and outlet chambers (38, 42) is a valve (104, 106) controlled dependent slowdown, characterized in that it comprises between the two inlet and outlet chambers (38, 42) and arranged along the same axis as that   of the equalizing piston (52) while being able to move   independently of it, a second stepped piston * (94) having, at its smallest frontal side (102) limiting the second inlet chamber (38), a seat of   valve (104) of the valve (104, 106) depending on the   slowed down and which, in the state of rest,   stop in which the second inlet chamber (38) has its smallest volume.