US 4,418,966 AGranted

Pump-less hydraulic brake system for automobiles

AssigneeVolkswagenwerk Aktiengesellschaft

InventorPeter Hattwig

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Abstract

A pump-less hydraulic brake system has a pair of independent brake lines, each connected to diagonally opposed front and rear wheel brakes, and a control valve mechanism disposed in each brake line. Each control valve mechanism has an electrically connectable inlet valve and outlet valve, actuatable to one of three combinations: (1) in which brake line pressure is determined by the brake pedal-actuated master cylinder; (2) in which the braking pressure in the respective brake line drops, and (3) in which the braking pressure remains steady. A pair of rear brake inlet valves are also provided, and the valves are controlled as a function of the relative rpm or changes in deceleration of the vehicle wheels. The rear brake inlet valves are also independently controlled, to limit maximum braking pressure to the rear wheel brake, as a function of rear axle weight. No more than one vehicle wheel locks at a give time, and vehicle stability and maneuverability, in combination with relatively high braking pressures, are assured.

A pump-less hydraulic brake system for vehicles having a pair of front wheels and a pair of rear wheels, and a pair of front wheel brakes and a pair of rear wheel brakes associated therewith, comprising:

(a) master brake cylinder means for providing pressurized brake fluid;
(b) a pair of independent brake lines, each connected to receive pressurized fluid from said master cylinder means, wherein each brake line is connected to deliver fluid to one front wheel brake and has a portion to deliver fluid to a diagonally opposed rear wheel brake;
(c) a control valve means disposed in each of said brake lines, wherein each said control valve means has an electrically connectable inlet valve and an electrically connectable outlet valve, and said inlet and outlet valves in each said control valve means are actuatable to one of a first combination, in which the fluid pressure in the respective brake line follows the pressure predetermined by the master brake cylinder, a second combination, in which the fluid pressure in the respective brake line drops, and a third combination, in which the fluid pressure in the respective brake line remains at the pressure prevailing at the start of said third combination;
(d) a pair of electrically connectable rear brake inlet valves, one disposed in the portion of each brake line leading to its respective rear wheel brake, which when actuated limits the fluid pressure in the associated rear wheel brake to the pressure prevailing when actuated;
(e) means responsive to vehicle weight for controlling said rear brake inlet valves independent of other control commands to said rear brake inlet valves;
(f) sensor means associated with each wheel for detecting the respective wheel's rotational speed and angular deceleration;
and
(g) control circuit means for receiving signals from each said sensor means and for selectively actuating the inlet and outlet valves of said control valve means and said rear brake inlet valves as a function of one of the magnitude of said signals and the ratio of said signals, wherein at any single time only one of the two control valve means is actuatable to said second combination.

5 more elements

Facts

Application

06/352,169Filed 25 Feb 1982

Priority

DE 310937212 Mar 1981

Granted

6 Dec 1983

Term ends

Not estimatedThe source records don’t support an estimate.

Classification6 codes

B60T 8/346
Hydraulic systems: 2 Channel systems
B60T 8/266
Characterised by producing differential braking between front and rear wheels: using valves or actuators with external control means
B60T 8/42
Having a fluid pressure regulator responsive to a speed condition: having expanding chambers for controlling pressure , i.e. closed systems
Y10S 303/04
Electrical pressure sensor: pressure signal used in electrical speed controlled braking circuit

Abstract

Claims6