FR2594395A1 - SLIDING CONTROL BRAKE SYSTEM - Google Patents

Abstract

Slip-regulated braking system, characterized in that it comprises a pressure regulating and monitoring valve 23 comprising three control chambers 22, 51, 54 and three pistons 24, 52, 56 cooperating with these control chambers, the first control chamber 22 being connected, via a pressure liquid path 48, to one of the pressure chambers 8, the second control chamber 51 being connected, via another pressure liquid path 50, to the other pressure chamber 9 of the master cylinder 2, and the third control chamber 54, designed as a valve chamber, being connected, on the one hand, to the reservoir for supplying pressure liquid and, on the other hand, to the pressure line 40 of the pump 26, the first piston 24 entering both the first control chamber 22 and the second control chamber 51 and cooperating with the second piston 52 which engages in the second and third e control chambers 51 and, respectively, 65. (CF DRAWING IN BOPI)

Description

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  The present invention relates to a braking system with

  sliding regulation, essentially comprising an amplifier actuated by a pedal and associated with a master cylinder to which the

  wheel brakes are connected through lines of

  pressure, a hydraulic pressure supply system

  auxiliary with a hydraulic pump and a fuel tank

  thought of pressure and supply of pressure liquid as well

  wheel sensors and electronic circuits for determining the

  the rotational behavior of the wheels and to produce

  electric brake pressure control gears, which are used to control electromagnetically actuated pressure liquid inlet and outlet valves located on the liquid lines of

  pressure to regulate slippage.

  In a two-circuit braking system of this type,

  According to German Patent Application No. 35 02 451.8, there is provided a control valve which, as a function of the pressure prevailing in a maltrc-cylinder working chamber, regulates the pressure prevailing in the pressure liquid path leading from the pump to the two brake lines, with anti-return valves being located in the pressure liquid path connecting the brake lines and the

  pump. In addition, this braking system is also equipped with a

  Differential pressure switch which is implanted on the electronic circuit and which makes it possible to detect and analyze the presence of a differential pressure. Through special pressure lines, this differential pressure switch is connected both to the pressure liquid line, leading to the

  pump to the brake lines, and to a malfunctioning working chamber

  master cylinder. The present invention aims to simplify the braking system and to implement, instead of several switches,

  valves and pipes, a single unit of relatively simple design

  and particularly high efficiency to monitor and regulate

the pressure of the pump.

  This object is achieved by means of a regulation and pressure monitoring valve comprising three control chambers and

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  three pistons cooperating with these control chambers, the first control chamber being connected, via a pressure liquid path, to one of the pressure chambers, the second

  control room being connected, via another

  jet of pressure liquid, to the other pressure chamber of the master cylinder, and the third control chamber, designed in the form

  valve chamber, being connected, on the one hand, to the feed tank

  pressure liquid and secondly to the pressure line of the pump, the first piston penetrating both into the first control chamber and the second control chamber and cooperating with the second piston which s' engages in the second and third control chambers, the second piston being applied, via a valve element, for example a ball of

  valve, against the valve seat of the third piston which is housed

  smoothing between two stops in the third control chamber and which comprises a longitudinal bore connecting the valve seat to the part of the third control chamber which communicates with the

pressure line of the pump.

  Preferably, the regulation and monitoring valve of

  pressure consists of several coaxial pistons arranged behind each other.

  others, one of which has an actuating ramp which co-

  operates with a probe of a differential pressure switch connected to the electronic circuit, this probe being maintained and guided

in the box of the valve.

  Advantageously, the first piston of the control valve

  pressure control is biased by a spring which, when the brakes are in the relaxed position, pushes the first piston against the second piston and, via

  the valve element, i.e. the valve ball, pushes the

  piston against the valve seat provided on the third piston,

  thus bringing the valve to the closed position.

  Conveniently, the first and second pistons of the pressure regulating and monitoring valve are designed as plungers, and the third piston comprising the longitudinal bore and the valve seat is held and guided by

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  sealingly in the cylindrical portion of the third control chamber. Ue shoulder or stop, provided in the third chamber

  the valve chamber, limit the travel of the third

  piston in case of pressure drop in the other two chambers.

  control elements and thus enable the valve element or the

  the valve to take off from the valve seat, so that the liquid from

  The pressure supplied by the pump can flow back into the

  pressure liquid through the longitudinal bore, the

  valve chamber and return pipe.

  The different objects and features of the invention are

  will now be detailed in the description which follows, made in

  As a non-limitative example, with reference to the appended figure which, in a simplified manner, represents, partly in section, in part

  purely schematic form, the main components of a system

  controlled sliding brake system according to the invention and

  of the regulating valve ensuring the monitoring of the pressure.

  In the embodiment shown, the braking system

  according to the invention comprises, as a brake pressure generator 1, a hydraulic unit consisting essentially of a tandem master cylinder 2 preceded by a vacuum amplifier 3. Via a rod 4, the force F exerted on the pedal

  brake 5 is transmitted in known manner to the amplifier

  pressure 3 and, from the latter, to the working pistons 6 and 7 of the

  tandem cylinder 2, after having been increased by the force

iary.

  When the brakes are in the relaxed position

  shown, the pressure chambers 8, 9 of the master cylinder

  with a pressure and feed compensation tank

  in pressure liquid 20 via central valves or

  green 10, 11, connecting channels 12, 13 provided inside the pistons 6, 7, and finally through annular chambers 14, bores 16, 17 and hydraulic lines 18, 19. At one of the two pressure chambers, in this case at the

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  pressure chamber 8, is connected the control input 21 and, via the latter, the first control chamber 22

  a regulating valve 23 ensuring the monitoring of the pressure.

  Through the pistons 24, 52 housed inside the val-

  23, the control pressure is transmitted to a spherical seat valve 25 which, on the one hand, is connected hydraulically

  on the pressure side of a hydraulic pump 26 and, on the other hand, is

  related to the pressure compensation tank 20. This pump is a

  hydraulic pump with electromotor drive (motor M). The conne-

  Electrical "m" and "Mass" (earth) are also symbolically represented. It should be noted that the piston 24 is also mounted sealingly with respect to its guide bore located in the

  casing of the regulating valve 23, by means of two rings of

  which, for the sake of clarity, are not represented

on the face.

  The two braking circuits I, II of the master cylinder 2

  are connected to two wheel brakes 31, 32; 33, 34 through val-

  hydraulically operated units 27, 28, which are open in the de-energized state.

  quoted, and through electromagnetically controlled valves, namely

  so-called inlet valves 29, 30 which are also open in posi-

  initial introduction. The parallel wheel brakes 31, 32 and, respectively, 33, 34 may, for example, as is the case here, be assigned to the wheels of an axle (rear wheels HR, HL, wheels

front VR, VL) or diagonals.

  The wheel brakes are connected to exit valves at

  electromagnetic control 35, 36 which are closed in the

  cited and which are connected to the pressure compensation tank 20

  via a hydraulic return line 37.

  Through non-return valves 38, 39 and a connecting line 40, the braking circuits I, II are connected to the

  auxiliary pressure supply system, that is to say at the pump

  26 and the control valve 23. The non-return valves 38, 39 open as soon as the auxiliary pressure exceeds a minimum value

  defined the instantaneous pressure in the braking circuits

  I, II between the inlet valves 29, 30 and the valves 27, 28. In addition, the auxiliary pressure has the effect of switching the valves 27, 28 in a second switching position o only a reduction of

  pressure towards the brake pressure generator 1 is

  possible core. For this purpose, corresponding non-return valves 41, 42 are connected in parallel with the valves 27, 28 or are structurally joined with these valves. These valves are designed under the

  form of hydraulically or electromagnetically controlled valves.

  The wheels of the vehicle are equipped with inductive sensors S1 to S4 which cooperate with a toothed disk rotated synchronously with the wheels and which produce electrical signals corresponding to the behavior in rotation of the wheels, that is to say at

  the speed of the wheels and its variations. Through the intermediary

  S1 to 54, these signals are transmitted to an electronic processing and signal combining circuit 44 which produces

  control of the brake pressure for temporary switching

  the inlet and outlet valves 29, 30, 35, 36 when

  blocking is detected, thus maintaining the pressure of

  constant braking, lowering and re-increasing it in good time.

  For this purpose, the magnets for actuating the inlet and

  output are excited via outputs A1 to A4. By way of

  simplification, the electrical connection lines provided between the connections A1 to A4 and the windings of the valves 29, 30, 34, 35

are not represented.

  The circuit 44 can be realized in known manner using

  of wired circuits or programmable electronic components,

  me microcomputers or micro-regulators.

  When producing pressure control signals

  the switching state of a different pressure switch

  The differential 43, which is part of the regulating valve 23 and, if appropriate, other signals are also analyzed. The signal input d is provided for this purpose. The start signal for starting the driving motor of the hydraulic pump 26,

  which only works during the regulation of the slide, is applied

  to the motor M via the connection m.

  The operating mode of the braking system is the following

  When the brakes are actuated, the force F exerted on the pedal and increased by the depression prevailing in the amplifier 3,

  is transmitted to the master cylinder pistons 6, 7. The central valves

  the 10, 11 are closed, so that in the pressure chambers 8, 9 and therefore in the braking circuits I, II, can be established a brake pressure that propagates to the wheel brakes 31, 32

  and, respectively, 33, 34 through the valves 27, 29 and, respectively,

ment, 28, 30.

  The pressure in chamber 8 is transmitted to the

  control 21 and the control chamber 22 of the control valve

  23, and increases the closing force, produced by the res-

  regulator fate 49, of the seat valve 25. Similarly, via the pressure line 50, the braking circuit

  It and, respectively, the pressure chamber 9 are connected to the second

  x control chamber 51 in which penetrate the two pistons

  24, 52. However, this has no effect because the hydraulic pump

that 26 does not work yet.

  When a blocking tendency is detected at one or more wheels by means of sensors S1 to S4 and circuit 44, slip control begins. The drive motor M of the pump 26 is turned on, so that an auxiliary pressure, proportional to the pressure prevailing in the control chambers 22, 51 and, respectively, in the pressure chambers 8, 9, and therefore to the force F exerted on the pedal, can then be established in the auxiliary pressure supply system and in the pipe

40 power supply.

  The auxiliary pressure causes the switching of the hydraulically operated valves 41, 42 and thus the closure of the braking circuits I, II (instead of being hydraulically actuated, the valves 41, 42 can also be electromagnetically). This prevents the master cylinder pistons 6, 7 from continuing to move in the direction of the force F exerted on the pedal, and the chambers of

  pressure 8, 9 to empty. Say that enough pressure is reached

  te, the auxiliary pressure supply system replaces the

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  brake pressure generator 1 through the con-

  feed pipe 40 and non-return valves 38, 39 which

  come then. Pressure liquid flows dynamically into the

  braking circuits I, II through the nonreturn valves 38, 39.

  The effective variation of the brake pressure in the wheel brakes 31 to 34 is determined by the inlet and outlet valves 29, 35, 36 which, via the lines A1 to A4, receive control signals brake pressure to regulate slippage. Anomalies of different types can be detected safely by comparing the pressure in the pressure chambers 8 and 9 of the master cylinder 2 and, respectively, in the

  lines 48, 50 leading to the pressure regulating valve

  23 with the instantaneous auxiliary pressure produced by the pump 26 and the control valve 23, while taking into account the operating state, that is to say normal braking or reaction of the slip control. When braking without slip control, pressure must be established in the pressure chambers

  8, 9, but not in the auxiliary pressure supply system.

  A failure of the braking circuit II, due for example to a leakage

  can be detected by means of the different pressure switch

  43. When the system is intact, the difference in

  is low or zero when slip control begins. In case of failure or malfunction of the pump 26 or the regulation valve 23, when a

  anomaly in the starting path of motor M or a similar defect

  In the pressure chamber 9 there is still a higher pressure

  than that prevailing in the pressure supply line

  auxiliary 40, even after the start of slip control.

  Anomalies can therefore be detected and reported by logically combining this state and others by means of the circuit 44. Depending on the type of fault, the circuit 44 automatically turns off the regulation of the slip completely or partially, that is to say only for certain wheel brakes, for effective braking

  remains possible via the braking circuit intact.

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  The control valve, which provides pressure monitoring and which is generally designated 23, comprises a total of four chambers 22, 51, 53, 54 arranged coaxially with each other and isolated from each other by three pistons 24 , 52, 55. While the two pistons 24, 52 subjected to the pressure prevailing in the braking circuits I and II are of identical design, the valve piston 55 is provided with a longitudinal bore 56 that can be closed by a ball valve 57 which is disposed between the valve seat 45 and the piston 52. The outer peripheral surface of the valve piston 55 has a cooperating operating ramp 46

  with a feeler 47 which is housed in a transverse bore of the bot-

  valve and slidable against the force of a contact spring 58 of the differential pressure switch

  43. If the hydraulic pressure produced by pump 26 is higher than

  re at the pressure prevailing in the control chambers 22 and / or 51,

  the valve piston 55 moves to the right until it recovers

  placed against the shoulder 59. The valve ball 57 can then be

  glue valve seat 45, so that a portion of the pressure liquid supplied by the pump 26 can flow back, through

  the return line 60 in the reservoir 20 to lower the pressure

  if we. If, as indicated previously, the valve piston 55 moves

  this towards the first control chamber 22, the probe-47

  is moved simultaneously against the spring force of

  tact 58, so that the differential pressure switch 43 is

  closes and a corresponding signal is provided to circuit 44.

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Claims (6)

  1. Slip regulation brake system, comprising   essentially an amplifier powered by a pedal and as-   associated with a master cylinder to which the wheel brakes are connected by   intermediate pressure lines, a hy-   Auxiliary pressure supply hydraulics equipped with a pump   hydraulic system and a tank for pressure compensation and   pressure liquid, as well as wheel sensors and   electronic circuits to determine rotational behavior.   wheels and to produce electrical control signals   braking pressure, which are used to control   electromagnetic actuated pressure liquid outlet and outlet on the pressure liquid lines to regulate the sliding, characterized in that it comprises a control valve   and pressure monitoring (23) comprising three chambers of   (22, 51, 54) and three pistons (24, 52, 56) cooperating with these   control chambers, the first control chamber (22) being   connected, via a pressure liquid path (48), to one of the pressure chambers (8), the second control chamber (51) being connected via another path of liquid   pressure chamber (50) to the other pressure chamber (9) of the   dre (2), and the third control chamber (54), designed in the form of a valve chamber, being connected, on the one hand, to the reservoir for supplying pressure liquid and, on the other hand at the pressure line (40) of the pump (26), the first piston (24) penetrating both the first control chamber (22) and the second control chamber (51) and cooperating with the second piston (52) which engages in the second and third control chambers (51 and 65, respectively), said second piston being applied via a valve element, for example a valve ball (57) against the valve seat (45) of the third piston (55) which is slidably received between two ridges (59, 61) in the third control chamber (54) and which has a longitudinal bore (56) - 10 -   connecting the valve seat (45) to the portion of the third control chamber (54) which communicates with the pressure line (40) of the pump (26).   Braking system according to claim 1, characterized   characterized in that the pressure regulating and monitoring valve (23) comprises a plurality of coaxial pistons (24, 52, 55) arranged one behind the other, one of which (55) is provided with a ramp   actuator (46) which cooperates with a probe (47) of an interrupter   differential pressure sensor (43), said probe being maintained and guided in the box of the valve.   Braking system according to claims 1 and 2,   characterized in that the first piston (24) of the regulating valve   and pressure monitoring (23) is biased by a spring (49) which, when the brakes are in the relaxed position, pushes   the first piston (24) against the second piston (52) and, by the   of the valve element, that is, the valve ball (57), pushes said second piston (52) against the valve seat (45) provided on the third piston (55), thereby causing the valve (25) in closed position.   4. Braking system according to any of the   Claims 1 to 3, characterized in that the first and second pistons (24 and 52, respectively) of the pressure regulating and monitoring valve (23) are designed as pistons   divers, and in that the third piston (55) comprising the   longitudinally (56) and the valve seat (45) is held and guided in a sealed manner in the cylindrical portion of the third chamber control (54).   5. Braking system according to any of the   preceding claims, characterized in that the shoulder or butt (59) provided in the third control chamber (54) forming the valve chamber, limit the stroke of the third piston (55) in the event of pressure drop in the two other control chambers (22, 51) and thus allow the valve element or the ball of   valve (57) to disengage from the valve seat (45) so that the liquid   of pressure supplied by the pump (26) may flow back into the reservoir.   - It - 2594395 see liquid supply pressure (20) through the longitudinal bore (56), the valve chamber (54) and the return line (60).   6. Braking system according to any of the   preceding claims, characterized in that the differential pressure switch (43) actuated by the actuating ramp   (46) of the third piston (55) is part of the electronic circuit.