Automotive Hydraulic Brake System

Abstract

An automotive hydraulic brake system is provided which exhibits an excellent pressure reduction performance to a low μ road while restraining an intake resistance of a fluid pump. For providing the hydraulic brake system, a gate-in valve is connected to an intake passage that connects a master cylinder to an intake side of the fluid pump. The gate-in valve selectively opens and closes the intake passage in accordance with a mutual relation between a master cylinder pressure and a pressure produced at an intake side of the fluid pump.

What is claimed is: 
     
         1 . A hydraulic brake system comprising:
 an intake passage connecting a master cylinder to an intake side of a fluid pump;   a discharge passage connecting a discharge side of the fluid pump to the master cylinder;   a first passage branched from the discharge passage and connected to a wheel cylinder;   a pressure reduction passage connected to a reservoir that reserves therein a pressure-reduced brake fluid from the wheel cylinder;   an outlet passage connecting the reservoir to the intake passage; and   a gate-in valve installed in the intake passage and closed when applied with a master cylinder pressure from the master cylinder, the gate-in valve selectively opening and closing the intake passage when the master cylinder pressure is applied to the gate-in valve and the fluid pump is in operation,   wherein when the master cylinder pressure is applied to the gate-in valve, the fluid pump takes therein a brake fluid through the gate-in valve that is carrying out the opening/closing operation.   
     
     
         2 . A hydraulic brake system comprising:
 a fluid pump driven by an electric motor; and   a housing that houses therein the fluid pump,   wherein the housing comprises:
 a master cylinder port connected to a master cylinder that is arranged outside the housing; 
 an intake passage connecting the master cylinder port to an intake side of the fluid pump; 
 a discharge passage connecting a discharge side of the fluid pump to the master cylinder port; 
 a first passage branched from the discharged passage; 
 a wheel cylinder port connecting the first passage to a wheel cylinder that is arranged outside of the housing; 
 a pressure reduction passage through which a brake fluid in the wheel cylinder is led into a reservoir through the wheel cylinder port; and 
 an outlet passage connecting the reservoir to the intake passage, 
   wherein the intake passage is provided with a pressure valve that carries out an open/close operation in accordance with a pressure difference between a pressure appearing at an upstream portion of the intake passage and a pressure appearing at a downstream portion of the intake passage with respect to the pressure valve,   wherein the pressure valve is set to carry out the open/close operation when the master cylinder pressure is applied thereto and the fluid pump is in operation, and   wherein the fluid pump is set to suck therein the brake fluid through the pressure valve.   
     
     
         3 . A hydraulic brake system as claimed in  claim 2 , further comprising a check valve that is installed in the outlet passage at a position between a first point where the intake passage is connected to the outlet passage and a second point where the pressure reduction passage is connected to the outlet passage and arranged to suppress a flow of the brake fluid in a direction from the first point toward the reservoir while permitting a reversed flow of the brake fluid. 
     
     
         4 . A hydraulic brake system as claimed in  claim 2 , further comprising an electromagnetic valve that is installed in the intake passage at a position between a first position where the intake passage is connected to the gate-in valve and a second position where the intake passage is connected to the outlet passage and arranged to selectively open and close the intake passage. 
     
     
         5 . A hydraulic brake system as claimed in  claim 2 , further comprising an electromagnetic valve that is installed in the outlet passage at a position between a first point where the intake passage is connected to the outlet passage and a second point where the pressure reduction passage is connected to the outlet passage and arranged to selectively open and close the outlet passage.