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US4783128: Brake pressure control unit with hydraulic power booster including antilocking and propulsion regulation
9 Claims, No Drawings
A brake pressure control unit operable by a hydraulic brake power booster and functionally corresponding to a tandem master cylinder for two statically pressurizable brake circuits has two casing bores spaced laterally apart. In one of the bores, the primary output pressure space bounded by the primary piston and floating piston is accommodated, and in the second bore, a piston which is also a floating piston, bounds the secondary output pressure space by a piston flange. The floating piston bounding the primary output pressure space on one side has the effect of building up, in the end control pressure spaces of the first and second bores, the control pressure acting on the second floating piston. This pressure leads to a displacement of the second floating piston in the sense of a pressure build-up in the secondary pressure space. The second floating piston is connected to a double-acting hydraulic cylinder, which is likewise accommodated in the second casing bore. By alternative pressurization and relief of working spaces of the hydraulic cylinder taking place via electrically controllable valves, antilocking and propulsion regulation functions are made possible in the brake circuit connected to the secondary output pressure space. The primary piston of the brake pressure control unit has an annular piston and a plunger piston, having annular seals which impart reciprocal sealing and also sealing from the primary piston bore. By these annular seals, axially extending, coaxially arranged separating spaces are bounded, these spaces imparting an effective media separation between the hydraulic booster circuit and the primary brake circuit.
- 1. Brake pressure control unit for a hydraulic dual circuit brake system of a road vehicle which is equipped with a hydraulic brake power booster which comprises a constantly supercharged hydraulic pressure accumulator and a brake valve connected to said accumulator, said accumulator inputting into a drive pressure space of the brake pressure control unit when said brake system is operated a pressure which is proportional to an operating force and acts directly on a drive surface of a primary piston, said pressure imparting a longitudinal displacement on said primary piston and a longitudinal displacement on a secondary piston in the sense of a brake pressure build-up in a primary output pressure space and in a secondary output pressure space of the brake pressure control unit, respectively, said vehicle having a static brake circuit connected to each of said primary and secondary output pressure spaces, said primary piston comprising an annular piston sealed from a bore of a casing, and a plunger piston arranged displaceably in a central bore of said annular piston and sealed from said annular piston, said plunger piston having a radial driving flange against which said annular piston is supportable by its end face toward the primary output pressure space, said annular piston and said plunger piston being pressurizable by said drive pressure inputtable into said drive pressure space and jointly displaceable in the sense of said brake pressure build-up, said plunger piston remaining displaceable by pedal power alone during a failure of an auxiliary pressure source, said control unit comprising:a first annular seal of said annular piston on the piston side, a flange facing the drive pressure space on which said first seal is arranged;a second annular seal fixed to said casing and arranged on the end section facing the primary output pressure space of the casing bore guiding said annular piston,said first and second annular seals forming an outer separating space in the shape of an annular gap;a third annular seal arranged at an inner bore of said drive flange of said annular piston; anda fourth annular seal arranged at said plunger piston and offset in the direction of said primary output pressure space,said third and fourth annular seals sealing said annular piston and said plunger piston from each other.
U.S. Patent Documents
Foreign Patent Documents
|Document Number||Assignees||Inventors||Issue/Pub Date|
|DE3347618||DAIMLER BENZ AG||Jul 1985|
|DE3417018||TEVES GMBH ALFRED||Nov 1985|