FR2565919A1 - BRAKE FORCE HYDRAULIC AMPLIFIER - Google Patents

Abstract

HYDRAULIC BRAKE FORCE AMPLIFIER FOR MOTOR VEHICLES INCLUDING A TANDEM MASTER CYLINDER TO EACH OF THE TWO OUTPUTS TO WHICH IS CONNECTED ONE OF THE TWO FRONT WHEEL BRAKE CYCLINDERS, INCLUDING A BRAKE FORCE AMPLIFIER PREVENT A PUMP SUPPLIED '' HYDRAULIC PRESSURE AGENT ON AN INTAKE TANK, AND INCLUDING A BRAKE VALVE CONTROLLED BY THE BRAKE PEDAL SO THAT A REGULATED PRESSURE PRODUCED BY THE PUMP IS DIRECTLY APPLIED, ON THE ONE HAND, TO THE PRIMARY MASTER PISTON OF THE MASTER CYLINDER AND, ON THE OTHER HAND, TO THE TWO REAR WHEEL BRAKE CYLINDERS, CHARACTERIZED IN THAT IN THE HYDRAULIC BRAKE LINES 23, 24 LEADING TO EACH OF THE TWO WHEEL BRAKE CYLINDERS 21, 22, A DISTRIBUTOR 25 INCLUDING MORE THAN TWO TRACKS AND AT LEAST TWO POSITIONS, THE DISTRIBUTOR BEING CONNECTED, THROUGH A HYDRAULIC CONTROL LINE (RESPECTIVELY 26 AND 27) TO THE OUTPUT (RESPECTIVELY 13 E T 14) OF THE MASTER CYLINDER 11 LEADING TO THE FRONT WHEEL BRAKE CYLINDER (RESPECTIVELY 15 AND 14) WHICH MATCHES IT DIAGONALLY AND BEING OPEN WHEN THE CORRESPONDING FRONT WHEEL BRAKE CIRCUIT (RESPECTIVELY II AND I) IS INTACT, AND CLOSED IN CASE OF PRESSURE LOWERING IN THE CORRESPONDING FRONT WHEEL BRAKE CIRCUIT (II AND I RESPECTIVELY).

Description

25659 19

  The present invention relates to a hydraulic amplifier

  braking force for motor vehicles comprising a master

  tandem cylinder to each of the two outlets to which one is connected

  two front wheel brake cylinders, comprising an amplifier

  braking force supplied by a pump taking hydraulic pressure agent from an intake tank, and comprising a braking valve controlled by the brake pedal so that a regulated pressure produced by the pump is directly applied, on the one hand, to the primary master piston of the master cylinder and, on the other

  part, to the two rear wheel brake cylinders.

  For safety reasons, in hy-

  braking force hydraulics of the type indicated above, it is desirable, in the event of a failure of a braking circuit of the front wheels, to prevent braking by means of the rear wheel brake cylinder arranged diagonally relative to this circuit, in order to maintain a relative braking balance of the vehicle and to prevent it from slipping. In such a three-circuit brake system, it is therefore important that the rear wheel brake cylinder placed diagonally to a front wheel brake cylinder is put out of action safely in the event of a fault, for example the brake system of the cylinder

front wheel brake affected.

  For this purpose, it is known (German patent application 31 50

  218) to provide a two-way valve; however, this posed some

  some problems related to the lowering of the wheel cylinder pressure.

  The present invention therefore aims to provide an amplifi-

  hydraulic brake force cator for a motor vehicle as indicated above in which, in the event of one of the two brake circuits of the front wheels failing, the rear wheel brake cylinder which corresponds to it diagonally is put safely off without causing problems of lowering

  the wheel cylinder pressure. The operation of the amplifier

  hydraulic braking force for motor vehicles must be reliable and optimal separation between the braking circuit

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  dynamics to which the regulated pressure is applied and the two circuits

  static brake cues to which the pressure is applied

  The master cylinder must be carried out.

  To solve this problem, it is provided, in accordance with the present invention, that in hydraulic brake lines

  leading to each of the two rear wheel brake cylinders is im-

  planted a distributor with more than two lanes and comprising at

  at least two positions, said distributor being connected, via

  diary of a hydraulic control line, at the end of May

  tre-cylinder leading to the front wheel brake cylinder placed diagonally and being open when the corresponding front wheel brake circuit is intact and closed in the event of a pressure drop in

  the corresponding front wheel brake system.

  In accordance with the present invention, a valve, to which the braking pressure of the front wheel braking circuit placed diagonally is applied, is therefore installed in the braking line leading to each rear wheel brake cylinder. The valve is normally in the open position for the pressure agent

  can be applied without obstacle to the rear wheel brake cylinder

  laugh. Only if the pressure drops, for example due to

  a leak in the braking circuit which corresponds to it in diag-

  the distributor closes and prevents any further braking

  at the corresponding rear wheel brake cylinder.

  In accordance with an advantageous embodiment, the distribution

  stopper comprises a piston-drawer biased towards one of its positions

  extreme conditions by the pressure of the control line and a

  ve which cooperates with the piston-drawer and which is open when the

  piston-drawer is in the extreme position, said valve being implanted

  ted between the inlet and outlet reserved for the regulated pressure. Suitably, the displacement stroke of the piston-drawer is such that a volume is generated in the branch leading to the rear wheel brake cylinder so that the pressure agent contained

  in the rear wheel brake cylinder concerned can loosen

  dre and therefore remove the braking force.

  An advantageous structural embodiment is characterized

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  in that the valve is located on the front side of the piston-drawer

  opposite the command input, which provides a construct-

  Particularly compact and space-saving.

  Another embodiment is designed so that the valve consists of a valve ball resting on the front side of the piston valve by means of a thin rod, the valve ball being placed in a chamber connected to the pressure regulated, and that the valve seat is placed on the side of the valve ball opposite said chamber. This embodiment also makes it possible to save space without compromising operating safety. In this latter embodiment, it is advantageous that

  the valve ball is slightly preloaded by a direct spring

valve seat.

  So that at the start of braking the piston-slide adopts

  the position necessary for the application of pressure to the cylinders

  dres rear wheel brake, it is, according to another embodiment, subjected to a slight elastic stress in the opening direction of the valve so that the piston-drawer occupies the valve opening position when the brake pedal is not pressed.

  The rear wheel brake cylinder can be removed

  cooked with a particularly high degree of safety if the

  There is a third position and a fourth path in the

  which the rear wheel brake cylinder is connected to the reservoir

  of admission and that it adopts when the connection between the master-cylin-

  dre and the corresponding rear wheel brake cylinder is inter-

  broken. In a first phase of the valve movement, the connection between the regulated pressure and the corresponding rear wheel brake cylinder is therefore interrupted and, consequently, a connection between the rear wheel brake cylinder concerned and the reservoir

  inlet is open so the pressure agent can detach

  apply tension to eliminate the braking effect.

  To achieve the third position and the fourth flies,

  a return valve is, in accordance with a structural embodiment

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  advantageous, implanted on the piston-drawer next to or behind the first valve and opens after the closure of the first valve to connect the outlet to the return outlet leading to the intake tank. The arrangement can be provided so that the return valve also has a valve ball which, by means of a rod fixed to the piston-drawer, is normally pushed against the valve seat

  opposite the piston-drawer.

  Another embodiment is arranged so that the return valve also includes a valve ball which, by means of a spring opposite the control input and housed in a cavity & of the

  piston-drawer, is pushed against the valve seat and can be lifted

  lifting of said valve seat by a pusher which is secured to the bot-

  and which, from the side of the control input, engages in an axial bore of the piston-drawer if the latter continues to move towards the control input after closing the

first valve.

  In addition, it is possible to obtain complete braking stop of the rear wheel brake cylinder in the event of a failure of the front wheel braking circuit which corresponds to it diagonally

  in that the distributor has a third position and a qua-

  third way in which the rear wheel brake cylinder

  respondant is connected to a non-return valve, said distributor a-

  opting for the third position after the link between the master-

  cylinder and the rear wheel brake cylinder was interrupted,

  after which the non-return valve is open to balance the pressure.

  between the rear wheel brake cylinder and the corresponding front wheel brake cylinder. In this case, the cylinder

  rear wheel brake is not slackened towards the rear

  intake manifold, but in the direction of the wheel brake system

  defective front. The valves are not simply turned off

  cooked, but they regulate the pressure of the rear wheel relative to that of the front wheel which corresponds to it diagonally. While the non-return valve can be installed outside the dispenser

  as a separate component, it is nevertheless preferable that it be

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integrated in the dispenser.

  The different objects and characteristics of the invention

  will now be detailed in the description which follows, made

  by way of nonlimiting example, with reference to the appended figures which represent:

  - Figure 1, a block diagram of a hydraulic amplifier

  braking force diagram for a motor vehicle in accordance with the

  vention comprising three braking circuits,

  - Figure 2, an axial section of a first embodiment

  sation of a distributor in accordance with the invention,

  - Figure 3, an axial section of a second embodiment

  sation of a distributor in accordance with the invention,

  - Figure 4, an axial section of a third embodiment of

  reading of a distributor in accordance with the invention,

  - Figure 5, an axial section of a fourth embodiment of

  reading of a dispenser according to the invention.

  In accordance with FIG. 1, the brake pedal 20 of a vehicle

  cule automobile acts, via a linkage 48, on the brake valve 19 located in a brake force amplifier 16 and on the primary master piston of a master cylinder in

  tandem 11 integrated in the brake force amplifier 16. The amplifier

  braking force factor 16 is supplied by a connected pump 18

  an intake tank 17 and can also be mounted, so that

  re usual, in parallel with an accumulator.

  At the primary output 13 of the tandem master cylinder 11 is connected a braking circuit II acting on the brake cylinder 15

  left front wheel, while a braking circuit I drives

  to the brake cylinder 14 of the right front wheel is connected to the

secondary output 12.

  To apply pressure to the primary master piston housed in the tandem master cylinder 11, the brake valve 19 delivers a regulated pressure GD coming from the pump 18, said regulated pressure GD being also available at the outlet 49 and being guided by the via a braking line 50, to the

braking 111 of the rear wheels.

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  Two brake lines 23 and 24 start from the brake line 50 of the rear wheels and lead to the brake cylinders of the rear wheels.

  rear wheels 21, 22. According to the present invention, devices

  distributors 25 are connected to said braking lines 23, 24 and each have an inlet 30 for the regulated pressure GD and an outlet 31 for transmitting the regulated pressure to the cylinders

  rear wheel brake 21, 22 when the distributors 25 are or

  green. In addition, there is provided on each distributor 25 a control input 32 which, via the hydraulic lines of

  command 26 and 27 shown in phantom, is linked to the con-

  brake line of the front wheel brake circuits Il and I which corresponds to it diagonally, so that the braking pressure of the front wheel brake circuit which corresponds diagonally to the

  distributor 25 is available at its control input 32.

  If the braking system is fitted with a safety device

  control of the wheel braking slip, SO closing valves are put into circuit in supply lines leading to the

  wheel brake cylinders 14, 15, 21 and 22, said iron valves

  SO procedure being normally open and being closed by the device

  check the braking slip of the wheels when applying

  rition of a wheel slip. In addition, SG opening valves lead wheel brake cylinders 14, 15, 21, 22 to the intake tank 17 to allow the pressure agent to be evacuated in the event of wheel slip control. brake cylinders

wheel 14, 15, 21, 22.

  It is essential that the distributors 25 in accordance with the

  be connected in the upstream brake lines

  SO closing valves for wheel slip control.

  The internal structure of a dispenser 25 described so far

  this will now be described with reference to Figure 2; in this mode

  embodiment, the distributor 25 has three channels and two positions

  tions for which not only the two extreme positions, but also any intermediate positions adopted to lower the pressure are occupied as a function of the prevailing pressure

7 2565919

  in the front brake cylinder in case of failure.

  Inside the distributor 25 designed in the form of a

  block is provided a cylindrical bore 51 in which is housed a

  tone-drawer 28 axially sliding. Sealing cups 52 seal the pressure chambers 53 and 54 one by

  relative to each other, said pressure chambers 53 and 54 being so-

  killed at opposite ends of the piston-drawer 28. An annular clearance formed between the two sealing cups 52 communicates with

  the atmosphere through a bore 56.

  By means of a helical compression spring 38 bearing on the bottom of the cylindrical bore 51 shown in the figure

  2, the piston-drawer 28 is biased to the left where it is in bu-

  tee against a closing plug 57 of the cylindrical bore 51, containing a valve 29. Inside the closing plug 57 is provided a chamber 35 open towards the piston-drawer 28, a radial bore 58 starting from said chamber 35 and leading to entrance 30 of

distributor 25.

  In addition, a helical compression spring 37 is housed

  into chamber 35 and pushes a valve ball 33 provided at the end

  half turned towards the piston-drawer 28. A thin rod 34 extending from the ball 33 to the piston-drawer 28 keeps the ball 33 raised from its valve seat 36 in the normal position shown in FIG. 2. The valve seat 36 is between ball 33 and the front side

left of the piston-drawer 28.

  Annular recesses 28 'provided at the end of the pis-

  ton-drawer 28, which in Figure 2 is the left end at this point form the pressure chamber 54 which is adjacent to the inlet

side 31 of the distributor 25.

  The pressure chamber 53 provided on the opposite side of the pis-

  your drawer 28 is connected to the input of cotvmande 32 provided on the device

tributary 25.

  The operating mode of the distributor 25 in accordance with Figures 1 and 2 is as follows: Due to the existence of the helical compression spring! L dal 38, the distributor 25 is normally in the open position as shown in Figure 2 and inlet 30, through the open valve 29, is connected to outlet 31. The braking circuits being intact, if braking is effected by actuation of the brake pedal 20,

  the braking pressure is simultaneously established in the three circuits

  braking circuits I, 11 and Ill. A substantially equal pressure is therefore established in the pressure chambers 53, 54 of the distributor

  of Figure 2 and the piston-drawer 28 retains the position indicated

  shown in Figure 2. Minor and usual pressure differences-

  the between the pressure chambers 53, 54 can be taken in

  account by a corresponding dimensioning of the compression springs

  helical sion 37, 38 so that the braking circuits

  being intact, the piston-drawer 28 still occupies the open position

shown in Figure 2.

  We will now assume that a leak occurs in the

  left braking system of the front wheels II and causes the

  braking pressure that previously prevailed there, causing

  thus a drop in pressure in the pressure chamber 53 of the device

  regulator 25 so that the regulated pressure GD still acting from the opposite side via the inlet 30 displaces the

  piston-drawer 28 of figure 2 to the right until the bil-

  the valve 33 rests tightly, under the action of the spring 37, on its valve seat 36 and closes the valve 29. At this time, the pressure agent can no longer flow towards the cylinder

corresponding rear wheel 21.

  The displacement stroke of the piston-drawer 28 is therefore chosen

  so that when moving to the right (Figure 2), the

  The light established in the pressure chamber 54 allows the pressure agent located in the rear wheel brake cylinder 21 to relax sufficiently to allow braking to stop. In other words, the pressure inside the rear wheel brake cylinder 21 moves the piston-drawer 28 to the right after the closure of the valve 29 until an expansion occurs

  or, as the case may be, braking stop.

  The reference figures assigned to the parts of the figures

  1 and 2 will be taken up in the following examples of embodiments

9 2565 9 19

  tion. In accordance with FIG. 3, it is provided, in addition to the first-

  re valve 29, a return valve 39 which connects the pressure chamber 54 to a return outlet 40 also shown in FIG. 1, said return outlet 40 leading to the intake tank via a pipe 59 shown in broken lines in Figure 1. The valve 39 also includes a valve ball 41 cooperating with a valve seat 42 located on the side of the ball 41

  opposite the piston-drawer 28. The valve ball 41 is connected to the piston

  ton-drawer 28 via a rod 43.

  In this case, the mode of operation during the first phase of a failure of a front wheel brake circuit I or II is analogous to the operation of the embodiment according to FIG. 2. However, after the closing of the first valve 29, the piston-drawer 28 can still move slightly towards

  the pressure chamber 53 by lifting the rod 34 of the valve ball

  ve 33, after which a stop 60 of the rod 43 engages with a con

  corresponding corresponding stop 61 of the piston-drawer 28 and, if the piston

  laugh 28 continues to move to the right (Figure 3), the valve ball 41 which is normally pushed by a spring 62 against its

  valve seat 42 lifts off from valve seat 42. Therefore,

  te a flow connection between the pressure chamber 54 and the return outlet 40 connected to the inlet reservoir of the pressure chamber 54, by means of a chamber 63 surrounding the rod 43 and the ball 41 and in which is also housed the spring of

  helical compression 62 and via a hy-

  hydraulic 64 extending the valve seat 42. The pressure agent

  contained in the rear wheel brake cylinder 21 or 22 which

  responds diagonally to the defective braking system can therefore

  relax in the intake tank 17.

  The embodiment of FIG. 4 differs from that of FIG. 3 only in that the two valves 29, 39 are no longer located side by side but axially one behind the other, the valve

  return 39 being housed in an axial cavity 44 made internally

  of the piston-drawer 28. A spring 45 housed in said cavity 44 pushes the valve ball 41 in the direction of the pressure chamber 53

2 2565919

  against its valve seat 42 provided at this location.

  A rod 43 extends, through an axial bore 47 of the pis-

  ton-drawer 28, from the bottom of the distributor 25 to a bore on

  the seat 42 of the valve ball 41.

  The operation is identical to that of the embodiment of FIG. 3, that is to say that in the event of a loss of pressure in the pressure chamber 53, the valve 29 closes at first, then the return valve 39 opens insofar as the valve stem 43 strikes the valve ball 41, thereby establishing a flow connection between the outlet 31 and the return outlet 40 via the cavity 44 when the valve ball 41 passes

  through a radial bore 65 formed in the piston-drawer 28.

  In accordance with FIG. 1, the return outlet 40 can be connected, not to the intake tank 17, but to the supply line.

  corresponding hydraulic control 26 and 27 through an an-

  ti-retour 46, which is represented by a dotted line 59 ′ in FIG. 1. In this case, during the opening of the return valve 39,

  the pressure remaining in the rear wheel brake cylinder

  respondent 21 or 22 is lowered through the non-return valve 46 to the brake circuits of the defective front wheels II and I. The

  non-return valve 46 must therefore be connected so as to open

  automatically if there is an overpressure in the brake cylinder of the corresponding rear wheels 21 or 22 and if the return valve 39

is open.

  FIG. 5 illustrates a solution similar to that of FIG.

  gure 2 in which the non-return valve 46 is however integrated in the distributor 25. For this purpose, a lateral bore 66 starts from

  the axial bore 51 containing the piston-drawer 28 immediately behind

  the pressure chamber 54, said bore leading to the valve

  check valve 46 adjacent to the control input 32.

  In this embodiment, the piston-drawer 28 also plays

  The role of the return valve 39 conforms to the embodiments.

  sation of Figures 3 and 4 in which, after closing the first valve 29, it is moved to the right (Figure 5)

  so that the pressure chamber 54 finally communicates with the a-

1 ES62565919

  lateral lesion 66, after which the pressure of the corresponding rear wheel brake cylinder 21 or 22 which has established itself at the outlet 31 can be lowered through the return valve 4b by

  via the control connection 32 towards the circuits

  diagonal braking circuits I! and 1 of the front wheels. Due to the load exerted on the slide piston 26 by the coil spring 38, the pressure prevailing during the lowering

  pressure from a rear wheel brake cylinder is always

  days slightly higher than the pressure of the braking system di-

corresponding front wheel gonal.

  In the embodiment of Figure 4, it is essential

  so that the two valves 29, 39 are coaxial and the return valve 39 is completely housed inside the piston-drawer 28

  so that its installation does not require any additional space.

  All the valves described have a common characteristic, namely that the regulated pressure supplied to the cylinders of

  rear wheel brake 21 and 22 cannot exceed the static pressure

  tick at the outputs 12, 13 of the tandem master cylinder, unless the helical compression spring 38 is only slightly dimensioned

  Consequently. In addition to their security function, distributors

  Teurs 25 therefore also play the role of regulators of the regulated pressure to adapt it to the static pressure of the brake cylinders of the front wheels 14, 15. Thanks to the use of distributors according to the invention, it is therefore no longer necessary to make a particular adjustment of the braking force amplifier 16 as a function of the

dynamically regulated pressure.

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Claims (12)

  1. Hydraulic brake force amplifier for vehicles   automotive vehicles comprising a tandem master cylinder to each of the two outlets to which one of the two front wheel brake cylinders is connected, comprising a braking force amplifier supplied by a pump taking hydraulic pressure agent from a intake tank, and comprising a brake valve controlled by the brake pedal so that a regulated pressure produced   by the pump is directly applied, on the one hand, to the master-pis-   primary tone of the master cylinder and, on the other hand, to the two rear wheel brake cylinders, characterized in that in the hydraulic brake lines (23, 24) leading to each of the two cylinders   wheel brake (21, 22), a distributor (25) is provided.   having more than two channels and at least two positions, said distributor   being connected, via a hy-   hydraulic (respectively 26 and 27) at the outlet (respectively 13 and 14) of the master cylinder (11) leading to the front wheel brake cylinder (respectively 15 and 14) which corresponds to it diagonally and being open when the braking circuit of the corresponding front wheel (respectively Il and I) is intact, and closed in the event of a pressure drop in the corresponding front wheel brake circuit (respectively II and I).   2. Motor vehicle brake in accordance with the claim   tion 1, characterized in that the distributor (25) comprises a nozzle   ton-drawer (28) urged by the pressure of the control line (26, 27) towards one of its extreme positions, and a valve (29) which   cooperates with the piston-drawer (28) and which is open when the piston   your drawer (28) is in the extreme position, the valve (29) being interca-   between the inlet (30) and the outlet (31) reserved for the regulated pressure.   3. Motor vehicle brake conforming to the claim   tion 2, characterized in that the valve (29) is located on the side   front of the piston-drawer (28) opposite the control input (32).   4. Motor vehicle brake in accordance with the claim   tion 3, characterized in that the valve (29) comprises a ball of   valve (33) resting on the front side of the piston-drawer (28) by the   through a rod (34), said valve ball (33) being placed in a chamber (35) connected to the regulated pressure, and in that the valve seat (36) is placed on the side of the ball valve   (33) opposite said chamber (35).   5. Motor vehicle brake in accordance with the claim   tion 4, characterized in that the valve ball (33) is loaded by   a spring (37) towards the valve seat (36).   6. Motor vehicle brake according to any one   as in claims 2 to 5, characterized in that the piston-slide   (28) is biased by a spring (36) in the opening direction of the valve so that the piston-drawer (28) (28) assumes the position   valve opening when the brake pedal (20) is not depressed cée.   7. Motor vehicle brake according to any one   as in the preceding claims, characterized in that the distribution   stopper (25) comprises a third position and a fourth track in which the rear wheel brake cylinder (21 and 22) is   connected to the intake tank (17) and which it adopts when the connection   sound between the master cylinder (11) and the wheel brake cylinder   corresponding rear (21 and 22) is interrupted.   8. Motor vehicle brake according to any one   that of claims 2 to 6 and in accordance with claim 7, charac-   terized in that a return valve (39) is installed on the piston-   drawer (28) next to or behind the first valve (29), said valve (39) opening after closing of said first valve (29) and   connecting the output (31) to the return output (40) leading to the re- intake manifold (17).   9. Motor vehicle brake in accordance with the claim   tion 8, characterized in that the return valve (39) also includes   a valve ball (41) which, by means of a rod (43) fixed to the piston-drawer (28), is normally pushed against the valve seat   opposite the piston-drawer (28). 14 2565919   10. Motor vehicle brake in accordance with the claim   tion 8, characterized in that the return valve (39) also comprises   a valve ball (41) which, using a spring (45) opposite   the control input (32) and housed in a cavity (44) of the piston-ti-   (28), is pushed against the valve seat (42) and, using   a rod (43) secured to the housing and protruding from the side of the   control port (32) in an axial bore (47) of the piston-drawer (28), can be lifted from the valve seat if the piston-drawer (28) continues to move towards the control input (32 )   after closing the first valve (29).   11. Motor vehicle brake according to any one   as in claims 1 to b6, characterized in that the distributor   (25) includes a third position and a fourth channel in the-   which the corresponding rear wheel brake cylinder (respec-   21 and 22) is connected to a non-return valve (46), said device   tributor adopting the third position after the connection between   the master cylinder (11) and the rear wheel brake cylinder (res-   pectively 21 and 22) has been interrupted, after which the anti-   return (46) is open to balance the pressure between the rear wheel brake cylinder (21, 22) and the wheel brake cylinder   before corresponding (respectively 15 and 14).   12. Motor vehicle brake in accordance with the claim   tion 11, characterized in that the non-return valve (46) is integrated in the dispenser (25).