Braking device having an automatic fluid pressure regulating function

A braking device having a function of automatically regulating a pressure of a fluid in a wheel cylinder for applying brake to a wheel of a vehicle, comprising:

• a high-pressure hydraulic system including a hydraulic pressure source, and a fluid passage connected to said hydraulic pressure source;
• a wheel-cylinder hydraulic system including said wheel cylinder, and a fluid passage connected to said wheel cylinder;
• a low-pressure hydraulic system including a reservoir and a fluid passage connected to said reservoir;
• a solenoid-operated directional control valve device for fluid communication of said wheel-cylinder hydraulic system selectively with said high-pressure hydraulic system or said low-pressure hydraulic system;
• an electric control device connected to said directional control valve device for controlling the directional control valve device to thereby control the fluid pressure in said wheel cylinder;
• and
• a variable flow restrictor valve device disposed in said fluid passage of said wheel-cylinder hydraulic system, for decreasing a rate of flow of the fluid through said fluid passage of said wheel-cylinder hydraulic system, with an increase in a pressure difference between said high-pressure and wheel-cylinder hydraulic systems, and with an increase in a pressure in said wheel-cylinder hydraulic system.

A braking device having a function of automatically regulating a pressure of fluid in a wheel cylinder for applying brake to a wheel of a vehicle, comprising:

• a high-pressure hydraulic system including a hydraulic pressure source, and a fluid passage connected to said hydraulic pressure source;
• a wheel-cylinder hydraulic system including said wheel cylinder, and a fluid passage connected to said wheel cylinder;
• a low-pressure hydraulic system including a reservoir and a fluid passage connected to said reservoir;
• a solenoid-operated directional control valve device for fluid communication of said wheel-cylinder hydraulic system selectively with said high-pressure hydraulic system or said low-pressure hydraulic system;
• an electric control device connected to said directional control valve device for controlling the directional control valve device to thereby control the fluid pressure in said wheel cylinder;
• a first pilot-operated variable flow restrictor valve disposed in said fluid passage of said high-pressure hydraulic system and having opposite pressure-receiving surfaces which receive as respective pilot pressures a pressure in said high-pressure hydraulic system and the pressure in said wheel-cylinder hydraulic system, in opposite directions, so that a rate of fluid flow through said first pilot-operated variable flow restrictor valve and thus through said fluid passage of said high-pressure hydraulic system decreases with the increase in said pressure difference between said high-pressure and wheel-cylinder hydraulic systems;
• and
• a second pilot-operated variable flow restrictor valve disposed in said fluid passage of said wheel-cylinder hydraulic system, and receiving as a pilot pressure the pressure in said wheel-cylinder hydraulic system, so that a rate of fluid flow through said second pilot-operated variable flow restrictor valve and thus through said fluid passage of said wheel cylinder hydraulic system decreases with the increase in the pressure in said wheel-cylinder hydraulic system.

A braking device having a function of automatically regulating a pressure of a fluid in a wheel cylinder for applying brake to a wheel of a vehicle, comprising:

• a high-pressure hydraulic system including a hydraulic pressure source, and a fluid passage connected to said hydraulic pressure source;
• a wheel-cylinder hydraulic system including said wheel cylinder, and a fluid passage connected to said wheel-cylinder;
• a low-pressure hydraulic system including a reservoir and a fluid passage connected to said reservoir;
• a solenoid-operated directional control valve device for fluid communication of said wheel-cylinder hydraulic system selectively with said high-pressure hydraulic system or said low-pressure hydraulic system;
• an electric control device connected to said directional control valve device for controlling the directional control valve device to thereby control the fluid pressure in said wheel cylinder;
• and
• variable flow restrictor means disposed in at least one of said fluid passage of said high-pressure hydraulic system and said fluid passage of said wheel-cylinder hydraulic system for decreasing a rate of flow of the fluid through at least one of said fluid passage of the high-pressure hydraulic system and said fluid passage of the wheel-cylinder hydraulic system with an increase in a pressure difference between said high-pressure and wheel-cylinder hydraulic systems, and with an increase in a pressure in said wheel-cylinder hydraulic system.