FR2647073A1 - PRESSURE MODULATOR FOR ANTI-LOCKING OR ANTI-SKATING SYSTEM - Google Patents

Abstract

Pressure modulator for anti-lock brakes or anti-skid system, comprising a pressure chamber 4 placed between a wheel brake cylinder RZ and a brake control cylinder HZ, and the volume of which can be varied by using a piston 10 actuated by a stretched flexible member 8 which passes over two drums, one of which 7 to be driven in rotation by a motor M and the other 9 is integral with the rod 11 of the piston. A clutch 1 controlled by an electronic unit ABV, ASR is interposed between the motor M and the drum 7.

Description

The invention relates to a pressure modulator for

  braking systems protected against blocking, or anti

  locking, and / or hydraulically driven anti-skid or anti-skid protection systems in motor vehicles, at least one piston being in cooperative connection, using a flexible tensioned member which is guided by a drum reversal of direction, with a shaft and a friction coupling which can be electromagnetically excited, and the piston rod can be controlled according to the torque transferred

by coupling.

  We know from DE-A-350286 (in the name of the applicant) a modulator

  of this type for anti-brake systems

  blocking (ABV). In this case, in the event of blockage, a pressure relief piston is separated from the pressure chamber by a chain which is wound on a shaft, the piston rod being able to be controlled according to the torque transmitted by the coupling to friction. This results in a reduction of the pressure prevailing in the

  braking, which prevents the wheels from locking.

  Such pressure modulators have worked well when installed in an ABV. However, it has been found that the flexible tensioned member must meet high requirements, because the

  forces that are applied and the accelerations are very high.

  In practice, the flexible tensioned member is executed in the form of a flyer chain with contiguous steel meshes. Tests have shown that plastic fabric bands or ropes are not satisfactory for the high demands and tear. It would therefore be advantageous to be able to reduce the tensile forces which are applied, so that the flexible tensioned member can be

  constructed of lighter material and smaller dimensions.

  In addition to anti-lock braking systems,

  also in modern motor vehicles

  skating in which, if a drive wheel threatens to get carried away, it is braked. For this purpose, it is necessary to apply, in the braking circuit of this wheel, a hydraulic pressure which is for example communicated by a pump, an accumulator or additional pressure sources (Druckblatt FAB, Publ. Nr RB

  43 603 DA) and requires significant costs.

  It is therefore the aim of the present invention to develop a pressure modulator of the type mentioned in the introduction which, for a simple construction and a small footprint, can be used both for anti-lock braking installations and for anti-skid systems, or for a combination of the two systems, which can reduce the forces acting on

the flexible stretched organ.

  This object is achieved by the fact that respectively the movable piston in opposition to the biasing force of a spring carries, on its end opposite to the pressure chamber, another direction reversing drum, on which the flexible stretched organ. According to advantageous methods, there are provided several pistons which can be moved each by means of a respective flexible tensioned member and direction reversing drums, by a friction coupling which can be electromagnetically excited, the friction couplings being arranged on a common shaft driven by a motor, the flexible tensioned member and the other direction reversing drum are arranged in such a way that the piston can be moved away from the pressure chamber or towards this if there are several pistons, guiding the tensioned organs

  flexible using the other direction reversing drum is effected

  killed in different ways, so that some pistons can be moved away from the pressure chamber and that the other pistons can be moved towards the pressure chamber; the path traveled by the piston, or the speed of the piston, is continuously captured by a path measurement system and is taken to an electronic monitoring or evaluation unit (ABV, ASR). Advantageously, the path measurement system is a voice coil, into which an iron core connected to the piston is immersed, the spring or springs is, or are, arranged so

concentric around the piston.

  Thanks to the arrangement of another direction reversing drum at the end of the piston opposite the pressure volume, not only the traction forces which are applied are halved (principle of the hoist) but it is also possible use the pressure modulator for anti-lock braking systems as well as for anti-skid systems or for a combination of the two systems. For this purpose, the other direction reversing drum must simply be arranged in such a way that the piston is moved in one case away from the pressure chamber and in the other case in the direction of this chamber, this which simply requires different guidance from the traction member

  flexible using the other direction reversing drum.

  We will now explain the invention using the embodiments and the appended drawing in which: FIGS. 1A and 1B schematically represent, in front and side view, a pressure modulator according to the invention, intended for

  anti-lock braking systems.

  FIGS. 2A and 2B schematically represent, in front and side view, a pressure modulator according to the invention intended for

anti-skid systems.

  Figure 3 schematically shows a top view of several pressure modulators according to the invention intended for a combination

  an anti-lock braking system and an anti-lock system

  skating. Figure 4 schematically shows the side view of the

  pressure modulators according to the invention of Figure 3.

  FIG. 5 represents a pressure modulator according to the invention in front view, comprising a spring arranged so

concentric around the piston.

  Figure 6 shows a pressure modulator according to the Figure in front view. In Figures 1A and 1B, 1 designates the friction coupling, the drive disc of which is driven by means of a shaft 2 by a motor (not shown). In a normal braking process, the pressure from the master cylinder HZ is sent by the open valve 3 into the pressure chamber 4 and reaches the wheel brake cylinder RZ. If the electronics then detect a risk of blockage, the friction coupling 1 is electromagnetically excited, its output disc 5 is attracted and

  applies, by the shaft 6, the torque to the reversing drum 7.

  The tensioned flexible member 8 is wound on the direction reversing drum 7, while, as it is guided on the other direction reversing drum 9, the piston 10 moves downward under the effect of the piston rod 11 in opposition to the spring 12, and therefore moves away from the pressure chamber 4, so that the volume of the pressure chamber 4 increases and that, consequently, the pressure decreases there. Valve 3 then closes, so that even an increase in pressure in the HZ master cylinder has no effect. A path measurement system 13 then continuously captures the path traveled by the piston 10 and transmits it to the system to the electronic ABV monitoring and evaluation unit which controls the torque to be applied using the intensity or the voltage of the current supplied to the coupling of

friction.

  In FIGS. 2A and 2B, the friction coupling is also designated by 1. Its drive disc is driven by means of a shaft 2 by a motor (not shown). When the electronics detect a danger of runaway (or slippage), the friction coupling 1 is electromagnetically excited, its output disc 5 is attracted and the torque is applied by the shaft 6 to the reversing drum of direction 7. The flexible stretched member 8 is wound on the direction reversing drum 7, so that, as it is guided on the other direction reversing drum 9, the piston 10 shifts under the effect of the piston rod 11 in opposition to the force of the spring 12, and consequently moves in the direction of the pressure chamber, where a pressure is established which is transmitted to the wheel brake cylinder RZ and which brakes the wheel that gets carried away. A valve 3 then blocks the pipe to the master cylinder HZ, normal actuation of the brakes from the master cylinder remaining possible at all times for safety reasons. A path measurement system 13 continuously captures the path traveled by the piston 10 and transmits it to the electronic monitoring and evaluation unit ASR which controls, using the amplitude or the current voltage supplied at the electromagnetic friction coupling, the torque to be transmitted. In Figures 3 and 4 is shown schematically a combination, consisting of an anti-lock braking installation and anti-skid systems, which comprises several pressure modulators. In this case, several friction couplings 1, to which the torque can be applied by means of a common shaft 2

  driven by a motor M, are arranged one behind the other.

  Each friction coupling can be electrically excited

  magnetically by ABV or ASR monitoring and evaluation electronics, and each of them can be moved by means of a member

  stretched hose 8 and direction reversing drums 7 or 9.

  In this case, the three pressure modulators shown in

  left in Figure 4 are applied to anti-installation

  blocking (ABV), the pistons 10 of which can deviate from the pressure chamber 4, while the two pressure modulators

  shown on the right in Figure are used as anti

  skating (ASR), whose pistons 10 can be moved in

  direction of the pressure chamber 4.

  As also shown in Figure 3, the pressure line coming from the master cylinder HZ is first brought to the pressure modulator controlled by the ASR electronics and, from its output, it reaches the pressure modulator. pressure controlled by electronics ABV, the output of which is then connected to the wheel brake cylinder RZ. In this way, the two functions ABV or ASR

  can be monitored and ordered in opposition.

  In Figure 4 is shown the structure of a motor vehicle with front wheel drive. In this case, there is no ASR control on the rear axle and, in the case of ABV, the brake pressure of the two rear wheels is controlled jointly, while the wheel brake cylinders front wheels can be respectively individually controlled as well by the control

ABV only with the ASR command.

  Figures 5 and 6 show a variant of the ABV pressure modulator, where a spring 12 is arranged concentrically around the piston 10. The operation corresponds to that of a

  pressure modulator as described in Figures 1A and 1B.

Claims (7)

Claims   1. Pressure modulator intended for braking installations protected against blocking, or anti-blocking, and / or adjustment systems against slipping, or anti-skating, hydraulically driven, in motor vehicles, in which at least one piston (10) is in cooperative connection, using a flexible tensioned member (8) which is guided by a direction reversing drum (7 '), with a shaft and a friction coupling (5) which can be electromagnetically excited, and the piston rod can be controlled according to the torque transferred by the coupling, characterized in that the movable piston (10) respectively in opposition to the biasing force of a spring (12) has 2 on its opposite end to the pressure chamber, another direction reversing drum (9), by which the tensioned member is guided flexible (8).   2. Pressure modulator according to claim 1, characterized in that several pistons (10) are provided which can be moved each using a respective flexible tensioned member and direction reversing drums (7, 9), by a friction coupling (1) which can be electromagnetically excited, the friction couplings (1) being arranged on a common shaft (2) driven by a motor (M).   3. Pressure modulator according to claim 1 or 2, characterized in that the flexible tensioned member (8) and the other direction reversing drum (9) are arranged so that the piston (10) can be moved away from the pressure chamber (4) or in the direction thereof.   4. Pressure modulator according to one of claims 1 to 3,   characterized in that, if there are several pistons (10), the guidance of the flexible tensioned members (8) by means of the other direction reversing drum (9) is effected in diffwo-diffu, entes, so that some pistons (10) can be moved away from the pressure chamber (4) and that the other pistons (11) can   be moved towards the pressure chamber (4).   5. Pressure modulator according to claim 2, characterized in that the path traveled by the piston (10), or the speed of the piston, is sensed continuously by a path measurement system (13) and is brought to a electronic monitoring or evaluation unit (ABV, ASR). 6. Pressure modulator according to claim 5, characterized in that the path measurement system (16) is a voice coil,   in which plunges an iron core connected to the piston.   7. Pressure modulator according to one of claims i to 6,   characterized in that the spring or springs (12) is, or are,   arranged concentrically around the piston.