Hydraulic braking system for an automotive vehicle having a pump and a damper

A hydraulic braking system for an automotive vehicle comprising:

• a master cylinder for generating a hydraulic braking pressure in response to operation of a manually-operated member;
• a power pressure source having a fluid pump for pressurizing a brake fluid and generating a hydraulic power pressure;
• a dynamic hydraulic pressure generator for regulating said hydraulic power pressure supplied from said power pressure source in response to operation of said manually-operated member and generating a regulated braking pressure, wherein said dynamic hydraulic power pressure generator comprises a hydraulic booster for actuating said master cylinder with said hydraulic power pressure supplied from said power pressure source in response to operation of said manually-operated member;
• a plurality of wheel brake cylinders for braking respective road wheels including driven wheels;
• a first changeover valve for selectively communicating at least said wheel brake cylinders for braking said driven wheel with one of said dynamic hydraulic pressure generator and said master cylinder;
• a second changeover valve disposed in a hydraulic circuit connecting said first changeover valve to said dynamic hydraulic pressure generator, and selectively placed in one of a first operating position where said first changeover valve is communicated with said dynamic hydraulic pressure generator, and a second operating positions where said first changeover valve is communicated with said power pressure source;
• a pressure sensor for detecting said hydraulic power pressure generated from said power pressure source;
• determination means for determining if said hydraulic power pressure detected by said pressure sensor exceeds a predetermined value;
• changeover means for repeatedly changing over said second changeover valve to be placed in one of said first operating positions and said second operating position of said power pressure changeover valve alternately when said determination means determines that said hydraulic power pressure exceeds said predetermined value;
• control valves disposed between said first changeover valve and each of said wheel brake cylinders for braking said driven wheels, said control valves controlling a hydraulic pressure in each of said wheel brake cylinders depending on a braking condition of said vehicle;
• and
• a damper disposed in a hydraulic circuit connecting said first changeover valve to said second changeover valve, said damper forming therein a space whose volume varies in response to a hydraulic pressure supplied thereinto.