Hydraulic braking system for an automotive vehicle

A hydraulic braking system for an automotive vehicle, comprising;

• a master cylinder having a housing defining therein a bore, a first piston slidably disposed in said bore and moved in response to depression of a brake pedal, a second piston slidably disposed in said bore at the side of said first piston opposite to said brake pedal, said first piston and said second piston defining therebetween a first pressure chamber communicating with a first port and a second port formed on said housing, said second piston defining at the side thereof opposite to said first chamber a second chamber communicating with a third port and a fourth port formed on said housing, said first piston blocking the communication between said first port and said first pressure chamber, and said second piston blocking the communication between said third port and said second pressure chamber, respectively, with said brake pedal depressed;
• a reservoir for storing an amount of brake fluid, said reservoir communicating with said third port of said master cylinder;
• first valve means for opening or closing the communication between said first port of said master cylinder and said reservoir;
• a plurality of wheel cylinders operatively mounted on respective wheels for braking said wheels, said wheel cylinders being divided into a first group of wheel cylinders and a second group of wheel cylinders;
• first anti-lock braking control means for controlling the pressure supplied from said second port of said master cylinder to said first group of wheel cylinders, said first anti-lock braking control means including an inlet valve provided between said second port and said first group of wheel cylinders respectively, a first drain passage for communicating said first group of wheel cylinders with said reservoir through an outlet valve provided in said first drain passage, respectively, and a first pump provided between said second port and said first drain passage, said first pump sucking the brake fluid from said first drain passage and discharging the pumped brake fluid to said second port;
• second anti-lock braking control means for controlling the pressure supplied from said fourth port of said master cylinder to said second group of wheel cylinders;
• second valve means for opening or closing the communication between said first drain passage and said reservoir;
• and
• valve control means for actuating said first valve means and said second valve means in accordance with a mode selected from a first mode for opening said first valve means and closing said second valve means, and a second mode for closing said first valve means and opening said second valve means.

A hydraulic braking system for an automotive vehicle, comprising;

• a master cylinder having a housing defining therein a bore, a first piston slidably disposed in said bore and moved in response to depression of a brake pedal, a second piston slidably disposed in said bore at the side of said first piston opposite to said brake pedal, said first piston and said second piston defining therebetween a first pressure chamber communicating with a first port and a second port formed on said housing, said second piston defining at the side thereof opposite to said first chamber a second chamber communicating with a third port and a fourth port formed on said housing, said first piston blocking the communication between said first port and said first pressure chamber, and said second piston blocking the communication between said third port and said second pressure chamber, respectively, with said brake pedal depressed;
• a reservoir for storing an amount of brake fluid, said reservoir communicating with said third port of said master cylinder;
• a plurality of wheel cylinders operatively mounted on respective wheels for braking said wheels, said wheel cylinders being divided into a first group of wheel cylinders and a second group of wheel cylinders;
• first anti-lock braking control means for controlling the pressure supplied from said second port of said master cylinder to said first group of wheel cylinders, said first anti-lock braking control means including an inlet valve provided between said second port and said first group of wheel cylinders respectively, a first drain passage for communicating said first group of wheel cylinders with said reservoir through an outlet valve provided in said first drain passage, respectively, and a first pump provided between said second port and said first drain passage, said first pump sucking the brake fluid from said first drain passage and discharging the pumped brake fluid to said second port;
• second anti-lock braking control means for controlling the pressure supplied from said fourth port of said master cylinder to said second group of wheel cylinders;
• third valve means for selecting one of a first position for communicating said reservoir with said first port and blocking the communication between said reservoir and said first drain passage, and a second position for communicating said reservoir with said first drain passage and blocking the communication between said reservoir and said first port;
• and
• valve control means for actuating said third valve means in accordance with a mode selected from a first mode for selecting said first position, and a second mode for selecting said second position.

A hydraulic braking system for an automotive vehicle, comprising;

• a master cylinder having a housing defining therein a bore, a first piston slidably disposed in said bore and moved in response to depression of a brake pedal, a second piston slidably disposed in said bore at the side of said first piston opposite to said brake pedal, said first piston and said second piston defining therebetween a first pressure chamber communicating with a first port and a second port formed on said housing, said second piston defining at the side thereof opposite to said first chamber a second chamber communicating with a third port and a fourth port formed on said housing, said first piston defining at the side thereof opposite to said first chamber a reservoir chamber communicating with a fifth port formed on said housing and having a volume varied in response to depression of said brake pedal, said first piston blocking the communication between said first port and said first pressure chamber, and said second piston blocking the communication between said third port and said second pressure chamber, respectively, with said brake pedal depressed;
• a reservoir for storing an amount of brake fluid, said reservoir communicating with said third port of said master cylinder;
• a plurality of wheel cylinders operatively mounted on respective wheels for braking said wheels, said wheel cylinders being divided into a first group of wheel cylinders and a second group of wheel cylinders;
• first anti-lock braking control means for controlling the pressure supplied from said second port of said master cylinder to said first group of wheel cylinders, said first anti-lock braking control means including an inlet valve provided between said second port and said first group of wheel cylinders respectively, a first drain passage for communicating said first group of wheel cylinders with said reservoir through an outlet valve provided in said first drain passage, and a first pump provided between said second port and said drain passage, respectively;
• second anti-lock braking control means for controlling the pressure supplied from said fourth port of said master cylinder to said second group of wheel cylinders;
• fourth valve means for selecting one of a first position for communicating said reservoir with said first port and said fifth port and blocking the communication between said reservoir and said drain passage, and a second position for communicating said reservoir with said drain passage and blocking the communication between said reservoir and said first and fifth ports;
• and
• valve control means for actuating said fourth valve means in accordance with a mode selected from a first mode for selecting said first position, and a second mode for selecting said second position.