Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Patent
1995-06-16
1996-12-31
Butler, Douglas C.
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
303 14, 3031161, 3031191, 3031134, 3031141, B60T 832, B60T 848, B60T 860, B60T 1312
Patent
active
055887180
DESCRIPTION:
BRIEF SUMMARY
The invention is based on a vehicle brake system as set forth hereinafter.
A hydraulic power-assisted brake system integrated in a wheel brake is known from the publication EP 0 025 714 A1. This has a power source with a reservoir, with a pump and with a pressure accumulator and an electrically controllable brake pressure setting valve, with an electromagnet and a brake pedal with an electrical sensor, and the system has an anti-lock control unit for controlling the brake pressure setting valve. An electrical converter which acts on the brake pressure setting valve can be adjusted by actuating the brake pedal. If the danger of wheel lock occurs when a brake pressure is set by actuation of the brake pedal, by means of the brake pressure setting valve, the anti-lock control unit drives the brake pressure setting valve against what is specified by the converter in order to reduce the brake pressure until such time as the danger of wheel lock is obviated. In the case of a failure of an electrical current supply to the pump and/or to the electrical converter and/or even to the anti-lock control unit, the relevant wheel brake fails. If the remaining wheel brakes of the same vehicle are connected to the same electricity supply, a failure of the electrical current supply causes a complete failure of the vehicle hydraulic brake system.
Vehicle hydraulic brake systems are known from the publications EP 0 265 623 A2, DE 40 29 793 A1, DE 31 31 856 A1, U.S. Pat. No. 4,462,642 and U.S. Pat. No. 4,902,075 which normally operate as electrically controllable power-assisted brake systems but which can be operated by muscle force in the case of a failure of power assistance by using, in each case, a twin-circuit emergency brake pressure generator which is, for example, configured as a normal main brake cylinder and which can be actuated by means of a brake pedal, with the support, for example, of a vacuum-operated servo brake, as is revealed in DE 40 29 793 A1. In accordance with EP 0 265 623 A2, electrically operating sensors intended for the electrical control of brake pressures are configured, for example, as a pedal force sensor (which is mechanically coupled to the brake pedal) or as a pressure sensor (which is connected to the emergency brake pressure generator). So-called displacement simulators are connected to the emergency brake pressure generators so that the driver experiences brake pedal displacements of comfortable length during power-assisted brake operation. In accordance with EP 0 265 623 A2 or DE 31 31 856 A1, for example, these displacement simulators can be switched on and off by valves and include cylinders, simulator pistons and simulator springs.
A vehicle hydraulic brake system with a main brake cylinder, which is known from the publication DE 41 02 496 A1, is further developed in order to generate wheel brake cylinder pressures with the aid of at least one pump and at least one change-over valve arrangement which can be controlled electrically. The electrical control takes place on the basis of signals which are proportional to the forces exerted on the brake pedal. Apart from the force or pressure sensors quoted for this purpose, DE 41 02 946 A1 mentions resistive and inductive displacement pick-ups and the measurement of a pedal actuation displacement. In a vehicle brake system operating with power assistance and using magnetic valves, EP 0 389 993 A1 reveals setting the brake pressure as a specified ratio of the brake pedal stroke. A brake pedal stroke detector provided for this purpose is represented as a potentiometer with a resistance track curved around the pivoting axis of the brake pedal.
Electrically controllable valves for the setting and/or relay of brake pressures and for shutting off the emergency brake pressure generators, and arranged between such power sources, the emergency brake pressure generators and the wheel brakes, can be configured in various ways as 2/2-way valves, 3/2-way valves, 3/3-way valves and 4/4-way valves, as revealed in EP 0 265 623 A2 and DE 31 24 755 A1. In contr
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patent: 5031968 (1991-07-01), Takata
patent: 5443306 (1995-08-01), Broome
Gaillard Alain
Winner Hermann
Butler Douglas C.
Greigg Edwin E.
Greigg Ronald E.
Robert & Bosch GmbH
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