Automotive brake control system

Claim 1

A brake control system for a motor vehicle, comprising a master cylinder with a brake pedal, wheel cylinders, a fluid pressure network interconnecting said master cylinder and said wheel cylinders, a fluid pressure control unit for controlling fluid pressure leading to at least one of said wheel cylinders, said fluid pressure control unit including a housing having formed therein a cavity which forms a part of said fluid pressure network associated with said at least one wheel cylinder and accommodate therein a valve for controlling said fluid pressure leading to said at least one wheel cylinder, a diaphragm assembly having a chamber and a diaphragm dividing said chamber into first and second subchambers, said second subchamber being communicating with the intake manifold of the engine, a plunger extending from said diaphragm through said first subchamber and connected to said valve and a compression sPring mounted in said second subchamber for biasing said diaphragm member toward a position in which said valve assumes its open position; a pneumatic control unit including an air chamber section, a pressure regulating section and a diaphragm operating section, said air chamber section including an air chamber vented from the atmosphere, an air valve mounted in said air chamber, said air chamber section having an opening which is defined by an annular valve seat on which said air valve is selectively seated, and a compression spring biasing said air valve to said annular valve seat for normally keeping said opening closed by said air valve, said pressure regulating section including a pressure regulating chamber communicating with said opening and with said first subchamber, a diaphragm member which defines said pressure regulating chamber and which has an opening, an annular valve seat mounted on the inner surface of said second diaphragm member, a compression spring mounted in said pressure regulating chamber and biasing said diaphragm member away from said opening, and a suction valve mounted in said pressure regulating chamber and connected rigidly to said air valve through a connecting rod, said suction valve being selectively seated on said annular valve seat against the action of the compression spring in said pressure regulating chamber, said diaphragm operating section including a vacuum chamber separated from said pressure regulating chamber by said diaphragm member of the pressure regulating section, a diaphragm chamber defined by an inner and outer diaphragm members, said outer diaphragm member being larger in working area than said inner diaphragm member, said inner diaphragm member separating said diaphragm chamber and said outer diaphragm member being exposed to the atmosphere, a connecting member rigidly connecting said inner and outer diaphragm members to said diaphragm member of said pressure regulating section, a conduit communicating with said air chamber and said diaphragm chamber, a first passage communicating with said diaphragm chamber and said intake manifold, a second passage communicating with said vacuum chamber and selectively with said first passage; a solenoid valve for controlling the communication between said first and second passages, said second passage being isolated from said first passage when said solenoid valve is deenergized whereby said inner and outer diaphragms and said diaphragm of said pressure regulating section are normally biased toward said suction valve, said suction valve being pressed upon said air valve when said second passage is permitted to communicate with said first passage with said solenoid valve energized whereby said pressure regulating chamber is caused to communicate with said intake manifold and the vacuum in said intake manifold is drawn into said first subchamber for moving said diaphragm member to a position in which said valve in said housing is urged to permit fluid communication in said housing; an electric control means electrically connected to said solenoid valve for energizing the same when actuated; and sensing means for sensing the revolution speeds of said at least one driving wheel and generating pulses the repetition rate of which is corresponding to the revolution speed of said at least one wheel, said electric control means being actuated when the angular wheel deceleration as detected from said revolution speed exceeds a predetermined level.