FR2601313A1 - BRAKING SYSTEM FOR MOTOR VEHICLE WITH SLIDING AND TRACTION CONTROL - Google Patents

Abstract

A BRAKE SYSTEM FOR A FRONT-DRIVE OR REAR-DRIVE VEHICLE CONSISTS OF A BRAKE PRESSURE GENERATOR 1 WHICH IS ASSISTED BY AN AUXILIARY FORCE AND TO WHICH A FRONT WHEEL AND A REAR WHEEL ARE CONNECTED THROUGH TWO SEPARATE CIRCUITS HYDRAULICALLY I, II. THIS SYSTEM IS EQUIPPED WITH AN AUXILIARY PRESSURE SUPPLY SYSTEM 19 WHICH IS SWITCHED ON ONLY DURING THE REGULATION PHASES OR WHEN THE BRAKES ARE ACTIVATED. PROVIDED FOR VALVE ARRANGEMENTS INCLUDING MULTI-WAY VALVES 9 TO 12, 42, 43 WHICH ARE OPEN IN THE REST POSITION AND THROUGH WHICH THE BRAKING PRESSURE GENERATOR 1 AND OR THE AUXILIARY PRESSURE SUPPLY SYSTEM 19 ARE CONNECTED AT WHEEL BRAKES 5 TO 8. DURING THE TRACTION SLIP REGULATION PHASE, THE PRESSURE AGENT PATHS TO THE NON-DRIVE WHEELS ARE CLOSED BY MULTI-WAY VALVES 13, 14 AND, RESPECTIVELY 40, 41.

Description

1 - 2601313

  The present invention relates to a slip and traction control braking system for a driving axle and a non-driving axle, comprising a brake pressure generator which is assisted by an auxiliary force and to which the brakes of a front wheels and one of the rear wheels are connected by means of two hydraulically separated circuits, a hydraulic auxiliary pressure supply system, valve arrangements through which, during the regulation phases, the pressure agent supply to the wheel brakes 10 can be interrupted and pressure agent from the auxiliary pressure supply system can be introduced in a controlled manner into the wheel brakes, outlet valves which, after being switched to open position, connect the pressure agent path leading to the two wheel brakes to a pressure compensation tank, open multi-way valves

  in the rest position, which can be switched to the closed position and installed on the press brake connection paths of the rear wheel brakes, and wheel sensors and electronic circuits intended to detect the rotational behavior of the wheels and to produce brake pressure control signals.

  A braking system of this type is described in German patent application 34 07 538. To reduce the use of means, this system comprises only two hydraulically separated braking circuits, to which one of the front wheels and, respectively, rear are connected, preferably diagonally. In addition to the pair of inlet / outlet valves necessary for regulating the braking and traction slip, there is provided, on the path of pressure agent leading to the non-driving wheel, another control valve 30 multidirectional which is normally switched to the open position and which, despite the limitation to two hydraulically separated circuits, makes it possible to achieve largely independent braking slip regulation at the front and rear wheels. If it is a front-wheel drive vehicle and if, therefore, the additional sup35 valve is installed on the rear wheel link, it is

2 2- 2601313

  possible, using this valve or, respectively, after closing the pressure agent path leading to the rear wheel, to introduce pressure of any level in a regulated manner into the front axle brake, without thereby affecting the running stability of the rear wheel connected to the same braking circuit. It is also possible to reduce the pressure at the front wheel in the presence of a constant rear wheel brake pressure. Furthermore, this additional valve makes it possible, with the assistance of the auxiliary pressure source, to regulate the traction slip, since, after the closure of this additional valve, braking pressure only reaches the drive wheel. In the braking system according to German patent application 34 07 538, the auxiliary pressure is taken, in the form of a regulated pressure, during the braking slip regulation phase, from the pressure generator. braking which is designed in the form of a master cylinder

  fitted with a hydraulic brake force amplifier. During the traction slip regulation phase, switching takes place using a three-way / two-position directional control valve to establish a direct connection with the hydraulic accumulator of the hydraulic pressure source. .

  To reduce the use of means for manufacturing a braking system with regulation of the braking and traction slip and to guarantee high operating safety, it has also already been proposed to design the braking pressure generator under the form of a master cylinder connected to a vacuum brake force amplifier located upstream, and to equip this device with a hydraulic auxiliary pressure supply system which is only switched on during the regulation phase

  slip (German patent application P 35 27 190.6).

  -The present invention therefore aims to provide a braking system with slip regulation which can be achieved with low implementation of means, which allows to perform, on the brake pressure of the front and rear wheels, regulation largely independent and sufficient for all the cases encountered in practice, and which, with at most reduced implementation of

- 3 2 2 601313

  additional means, allows to regulate the traction slip

  in front or rear wheel drive vehicles.

  It turned out that this object could be achieved in a surprisingly simple and technically advanced manner by a braking system of the type indicated above, the refinement of which resides in that the auxiliary pressure supply system is essentially constituted a hydraulic pump, which can be started during regulation and / or when the brakes are actuated, an auxiliary pressure regulating valve, and a multidirectionally controlled valve which is located on the pressure agent circuit connecting the discharge side to the suction side of the pump, which is open in the rest position and which can be switched to the closed position during the traction slip regulation phase, and in that the arrangements of valves include multi-way valves which are open in the rest position, which can be switched to the closed position, which are located on the pressure agent paths leading from the generator brake pressure and the auxiliary pressure supply system to the wheel brakes, and with which the auxiliary pressure supply system can be connected to the wheel brakes, instead of the

  brake pressure generator, during regulation phases.

  Despite a comparatively very limited use of components, this system has three regulation channels and is suitable, without additional components - apart from an extension of the electronic regulator - also for regulating the braking slip of a front-wheel drive vehicle. As described in detail below, its use in rear-wheel drive vehicles requires only two additional valves to regulate traction slip. According to an advantageous embodiment of the invention, the valve arrangements, which are located on each of the two hydraulically separated circuits and arranged in the pressure agent paths leading from the brake pressure generator and from the supply system in auxiliary pressure to the wheel brakes, comprise at least one multi-way valve. open in position

4 - 2601313

  rest. According to the invention, these valves make it possible to hydraulically connect the brake pressure generator and the auxiliary pressure supply system in parallel with the wheel brakes. In contrast, in another embodiment, the multi-way valves of the valve arrangements, which are located on the pressure agent paths leading from the brake pressure generator and the auxiliary pressure supply system to the brakes of wheels and which are open in the rest position, are located one behind the other on the pressure paths which lead from the brake pressure generator to the wheel brakes, the auxiliary pressure supply system being hydraulically connected, to through check valves arranged between these two multi-way valves, to the agent path

  pressure which connects the brake pressure generator to the wheel brakes.

  If it is a rear pmpilsi: n vehicle, it is possible, as indicated above, to regulate with the same braking system both the braking slip and the traction slip, if a multi-way valve open in rest position is also located on each of the

  pressure agent connection leading to the front wheel brakes; during the traction slip regulation phases, the supply of pressure agent to the non-driving front wheel is interrupted by these additional valves.

  Suitably, in a two-brake system

  circuits of the type indicated above, the wheels of the vehicle are connected diagonally to the two hydraulic braking circuits.

  The various objects and characteristics of the invention will now be detailed in the description which follows, given by way of nonlimiting example, with reference to the appended figures

  which represent: - Figure 1, in simplified and partially schematic form, the main components of a braking system according to the invention, intended for front-wheel drive vehicles, - Figure 2, in the same form of representation as the

- 5- 2601313

  FIG. 1, a braking system for vehicles with rear pulsin, FIG. 3, in the same form of representation, another embodiment also intended for vehicles with rear propulsion. The braking system according to Figure 1 consists of

  a brake pressure generator 1 which, for its part, consists of a tandem master cylinder 2 and a vacuum amplifier 3 mounted upstream. The braking force is exerted on the brake pressure generator 1 by means of a brake pedal 4.

  It is a brake pressure generator with two hydraulically separated brake circuits I, II. The brakes of a front wheel VL are respectively connected diagonally to the braking circuits I and II; VR and a rear wheel HR; HL. On each of the pressure agent paths leading from the brake pressure generator 1 to the wheel brakes 5, 6; 7, 8 are installed two multi-way valves 9, 10 and, respectively, 11, 12

  which, normally, that is to say in the rest position, are open.

  In addition, on each of the pressure agent paths leading to the rear wheels HR, HL is installed a multi-way valve 13 and, respectively, 14 which, in the rest position, also allows the hydraulic agent to pass. On the other hand, the front driving wheels VL, VR are connected directly to the second multi-way valve and, respectively, 12 located on the pressure agent path 25 leading from the brake pressure generator 1 to the brakes

wheels 5, 6; 7, 8.

  There is also provided a reservoir for the accumulation of a pressure agent or of pressure compensation 15 to which the two braking circuits I, II or, respectively, the working chambers 30 located -in the interior of the master cylinder in tandem 2 are connected from

  conventional way as long as the brakes are not applied. In addition, the brakes 5, 7 of the front drive wheels VL, VR are connected to the reservoir 15 through multidirectionally controlled valves 16, 17 closed in the rest position and through a return line 35 for pressure agent 18.

- 6 -

  Finally, the braking system according to the invention is also equipped with an auxiliary pressure supply system 19 which essentially consists of a hydraulic pump with electromotive drive 20, a pressure regulation valve braking 21, and a blocking valve, that is to say a multi-way valve 22 open in the rest position. The regulating valve 21 and the multi-way valve 22 are installed hydraulically one behind the other on the circuit of the hydraulic pump 20, which connects the discharge side of the pump to its suction side via supply lines. pressure agent 23, 24. Line 24 is also connected to compensation tank 15. A pressure relief valve 25 guarantees

  that the maximum admissible pressure is not exceeded.

  The pressure regulating valve 21 is connected to one of the two braking circuits, in this case to the braking circuit I of the tandem master cylinder 2, via the pressure agent line 26 shown. in a broken line, and includes inside a throttling point (not shown) with the aid of which the auxiliary pressure can be adjusted to a value as a function of the pressure of the roll cylinder which is transmitted via of line 26, this value being proportional to the pressure prevailing in the master cylinder 2 and therefore to the force exerted on the brake pedal 4. On the other hand, after the switching of the multi-way valve 22 and the closing of the circuit by means of the pressure agent lines, the auxiliary pressure prevailing

  in the supply system 19 quickly reaches the maximum value limited by the desurerirn valve 25.

  Through two non-return valves 27, 28 which isolate the two circuits from each other and which, when the auxiliary pressure supply system 19 is not in operation, prevent the agent

  pressure to flow towards the pump 20, the auxiliary pressure supply system 19 is connected to the two braking circuits I, II of the brake pressure generator 1, that is to say between the two valves 9 , 10; 11, 12 which are located one behind the other, which are open in the rest position and which

- 7 - 2601317

  link the cylinder 2 to the wheel brakes 5, 6; 7, 8 diagonally.

  In the rest position, that is to say when the brakes are not actuated, or in normal braking, that is to say unregulated, all the multi-way valves adopt the switching positions shown. In this case, all the valves are designed in the form of valves with two directicrrlle

  channels / two positions with electromagnetic control.

  Finally, to monitor the operation of the brakes, a pressure difference switch 29 is also provided which compares the pressure prevailing in the two braking circuits I, II and, respectively, in the brake chambers. working of the master cylinder in tandem 2 and also compares it to the auxiliary pressure of the auxiliary pressure supply system 19. With the aid of a switch 30 which is controlled according to the stroke and

  which can be actuated when an inclined ramp 32 of an intermediate piston 31 of the tandem master cylinder 2 cooperates with a pusher 33, a signal can also be produced when the advance of the piston is excessive and certain switching functions, for example exem20 pie a start-up of the hydraulic pump 20 of the auxiliary pressure supply system 19 can be carried out.

  Finally, there is also provided a switch 34 which is connected to the brake pedal, which can serve as a brake light switch, and with which the auxiliary pressure supply system 19 or, respectively, the pump can be turned on. works when the brakes are applied, possibly depending on other conditions or criteria, such as the presence of a slip regulation signal. In addition, the braking system according to the invention com30 takes an electronic regulator 35 at the inputs E1 to E4 from which signals on the rotation behavior of the wheels are sent, these signals being taken using wheel sensors, for example inductive transducers. After shaping and logical combination of these sensor signals using electronic circuits or microcomputers provided inside the regulator 35, signals

- 8 - 2 601313

  brake pressure control devices are produced and transmitted, through outputs A1 to An, to the various multidirectionally controlled valves 9 to 14, 17, 19 and 22 by means of electrical lines not shown. The regulator 35 can also receive the signals produced using the pressure difference switch 29, the switch 30 controlled according to the stroke, and the pedal switch 34. Appropriately, control outputs are also provided. on the electronic regulator 35 for the motor M of the hydraulic pump 20, for indicator lights (not shown) and for similar equipment.

  The operating mode of the braking system in accordance with FIG. 1 is as follows: During normal unregulated braking, all the multi-way valves 9 to 14, 16, 17 and 22 remain in the rest position. The braking pressure, which is controlled by actuating the pedal 4 and which is amplified by a vacuum using the member 3, is transmitted to the wheel brakes 5 to 7 via the braking circuits hydraulically separated I, II and through the open multi-way valves 9, 10,

  13; 11, 12, 14. The auxiliary pressure supplied by the supply system 19 is not required, which explains - possibly except in special cases, such as the application of a very high force on the pedal or a very large displacement of the intermediate piston 31 - that the electric motor M of the hydraulic pump 25 remains stationary.

  However, if there appears to be a blocking tendency of which the electronic regulator 35 is informed by means of the signals from the wheel sensors 36 to 39, the regulation of the braking slip is triggered. The hydraulic pump 20 is started. At tra30 towards the pressure regulating valve 21, an auxiliary pressure proportional to the braking pressure of the braking circuit I is produced in the auxiliary pressure supply system 19 and transmitted to the two braking circuits I, II through the non-return valves 27, 28. Using the pairs of inlet / outlet valves 10, 16; 12, 17, the braking pressure of the two diagonals can

- 9 - 2 601313

  then be kept constant, decreased and, if necessary, increased, the pressure agent being supplied by the auxiliary pressure supply system 19. By switching the multi-way valves 9, 11 located on the agent path pressure leading from the cylinder 2 to the wheel brakes, the working piston cannot continue to move inside the cylinder 2 during each regulation phase. The multi-way valves 13, 14, through which the rear wheels are hydraulically connected, keep the braking pressure of the rear wheels constant while increasing

  or by decreasing that of the front wheels.

  The braking system according to FIG. 1 also makes it possible, without any other component being necessary - if not a corresponding extension of the electrical circuits of the regulator 35 -, to regulate the slip of traction. In fact, as soon as the sensors 37, 39 of the drive wheels signal a traction slip, the auxiliary pressure supply system 19 is switched on and the brakes 6, 8 of the rear non-drive wheels are hydraulically separated by switching the valves. multi-way two-way / two position 13, 14. Simultaneously, by switching the valves 9, 11, an interruption of the pressure agent from the auxiliary pressure supply system 19 through the master cylinder 2 is prevented. Using the pairs of inlet / outlet valves 10, 16; 12, 17, the drive wheels can be subjected to a braking pressure in a metered manner, which makes it possible to bring back

  traction slip at an optimal value.

  To produce the auxiliary pressure in the supply system 19, the hydraulic pump 20 is started and the pressure agent circuit which passes through the lines 23, 24 is closed 30 by switching the two-way two-way valve

channels / two positions 22.

  The embodiment of the braking system according to the invention and represented in FIG. 2 differs from that described with reference to FIG. 1 only by the installation of a valve 35 with several channels, open in the rest position , on the

- 2 - 601313

  pressure agent connection leading to the brakes 5, 7 of the front wheels.

  The presence of these additional valves 40, 41 then also makes it possible to use the braking system according to the invention for rear-wheel drive vehicles. In fact, during the traction shift regulation phase, the brakes 5, 7 of the non-driving front wheels VL, VR are hydraulically separated from the two circuits diagonally I, II using the valves 40, 41, of so that the braking pressure introduced during the traction slip regulation phase is only applied to the rear drive wheels HR, 10 HL.

  In this embodiment, the multi-way valves 13, 14 located on the connection paths leading to the rear wheels are not necessary to regulate the traction slip, but are subsequently necessary to regulate the braking slip in order to ability to vary brake pressure in front wheel brakes largely independent of that in rear wheel brakes, as previously described

  About the embodiment according to the invention 1.

  The braking system in accordance with FIG. 3 differs from the embodiments in accordance with FIGS. 1 and 2 by the difference in installation of the multi-way valves, with the aid of which the introduction of the auxiliary pressure coming from the system d supply 19 is controlled during the phases of regulation of the braking and traction slip. In the braking system according to FIG. 3, the multi-way valves 42, 43, which are open in the rest position, are mounted in series with the non-return valves 27, 28. The second valve located on the travel paths pressure agent leading from the maland-cylinder in tandem 2 to the wheel brakes, that is to say the valve 10 or, respectively, 12 in FIGS. 1 and 2, is eliminated in the hydraulic circuit conforming to FIG. 3 or, respectively, is replaced by the valve 42 or, respectively, 43. In the arrangement of the valves according to FIG. 3, the brake pressure generator 1 and the auxiliary pressure supply system 19 are hydraulically connected hy35, in a certain measurement, in parallel with the brakes of - ll - 2601313

wheels 5 to 7.

  For the operational safety of the braking system, this arrangement has advantages because, in the event of unregulated braking, only one and no longer two (or, respectively, two and no more than three) multi-way valves are located on pressure agent paths leading from master cylinder 2 to the brakes

wheels 5 to 8.

  The braking system according to FIG. 3 is also provided for a rear prnlsic, which explains that, as in example 10 of FIG. 2, an additional valve 40 and, respectively, 41, necessary to regulate the traction slip, is located on the hydraulic connection path leading to the non-driving wheels VL, VR. In addition, the operating mode of the braking systems 15 in accordance with FIGS. 2 and 3 is identical to that of the braking system according to FIG. 1. For the sake of simplification, the sensors and the electronic regulator have not been shown in the figures. 2 and 3.

- 12 -

Claims (7)

  1. A slip and traction control braking system for a driving axle and a non-driving axle, comprising a brake pressure generator which is assisted by an auxiliary force and to which the brakes of one of the front wheels and of one of the rear wheels are connected by means of two hydraulically separated circuits, a hydraulic system for supplying auxiliary pressure, valve arrangements. by means of which, during the regulation phases, the supply of the pressure brakes to the wheel brakes can be interrupted and pressure agent from the auxiliary pressure supply system can be introduced in a controlled manner into the wheel brakes, outlet valves which, after being switched to the open position, connect the pressure agent path leading to the two wheel brakes to a pressure compensation tank, valves in several open ways in the rest position, which can be switched to the closed position and installed on the press brake connection paths of the rear wheel brakes, and wheel sensors and electronic circuits intended to detect the rotational behavior of the wheels and to produce brake pressure control signals, characterized in that the auxiliary pressure supply system (19) consists essentially of a hydraulic pump (20), which can be started when regulating and / or when applying the brakes, an auxiliary pressure regulating valve (21), and a multi-way valve (22) which is installed on the circuit pressure agent connecting the discharge side to the suction side of the pump, which is open in the rest position and which can be switched to the closed position during the traction slip regulation phase, and in that the valve arrangements include multi-way valves (9 to 12, 42, 43) which are open at   rest position, which can be switched to the closed position, which are located on the pressure agent paths leading from the general - 13 - 22601313   brake pressure (1) and the auxiliary pressure supply system (19) to the wheel brakes (5 to 8), and with which the auxiliary pressure supply system (19) can be connected to the brake wheels, instead of the brake pressure generator (1), during the regulation phases. 2. Braking system according to claim 1, characterized in that the valve arrangements, which are located on each of the two hydraulically separated circuits (I, II) and arranged on the pressure agent paths leading from the pressure generator 10 braking (1) to the wheel brakes (5 to 8) and the auxiliary pressure supply system (19) to the wheel brakes (5 to 8), each comprise at least one multi-way valve (9 to   12; 42, 43) open in the rest position.   3. Braking system according to claim 2, carac15 terized in that the multi-way valves (9, 11i; 42, 43) of the valve arrangements, which are open in the rest position, allow the generator to be hydraulically connected. brake pressure (1) and the auxiliary pressure supply system   (19) in parallel with the wheel brakes (5 to 8).   4. Braking system according to claim 2, characterized in that the multi-way valves (9 to 12) of the valve arrangements, which are located on the pressure agent paths leading to the brake pressure generator (1 ) and the auxiliary pressure supply system (19) to the wheel brakes (5 to 8) and which are open in the rest position, are located one behind the other on the pressure agent paths which lead from the brake pressure generator (1) aux wheel brakes (5 to 8).   5. Braking system according to any one of re30 vendications 1 to 4, intended for rear-wheel drive vehicles, characterized in that, on the pressure agent connection paths leading to the front wheel brakes (5, 7), are installed valves with several additional channels (40, 41) which are closed in the rest position and which make it possible to interrupt the supply of the front wheel brakes (5, 7) with pressure agent during the -14 - 2601313 traction slip phase.   6. Braking system according to any one of claims 1 to 5, characterized in that the wheels of the vehicle (VL, HR; VR, HL) are connected diagonally to the two hydraulic circuits (I, II).   7. Braking system according to any one of claims 1 to 6, characterized in that the auxiliary pressure supply system (19) can be switched on when the brakes are actuated and produced during the phase brake slip regulation, an auxiliary pressure proportional to the force exerted on the pedal.