Power plants – Pressure fluid source and motor – Pulsator
Reexamination Certificate
2000-01-28
2001-08-21
Ryznic, John E. (Department: 3745)
Power plants
Pressure fluid source and motor
Pulsator
C303S114100
Reexamination Certificate
active
06276136
ABSTRACT:
This application is based on and claims priority under 35 U.S.C. §119 with respect to Japanese Application No. 11(1999)-19861 filed on Jan. 28, 1999, the entire content of which is incorporated herein by reference.
FIELD OF THE INVENTION
The present invention generally relates to a brake pressure apparatus for a vehicle. More particularly, the present invention pertains to a hydraulic pressure brake apparatus which provides braking forces to the respective wheels of an automotive vehicle.
BACKGROUND OF THE INVENTION
A conventional hydraulic pressure brake apparatus generally includes a brake pedal, a master cylinder having a cylinder body formed therein with a cylinder bore and a piston slidably fitted in the cylinder body in such a manner that the piston is moved during depression of the brake pedal and with a pressure chamber being defined in the cylinder bore at the front side of the piston, a plurality of wheel brakes in fluid communication with the pressure chamber to provide braking forces to the respective wheels when a fluid under pressure is applied to the wheel brakes as a result of the depression of the brake pedal, an accumulator for accumulating a high-pressure brake fluid, a first valve for establishing and interrupting fluid communication between the accumulator and the wheel brakes, and a second valve for establishing and interrupting fluid communication between the brake chamber of the master cylinder and the wheel brakes.
This conventional brake apparatus includes two brake operation modes, a normal brake operation mode and an automatic brake operation mode. The normal brake operation mode involves supplying braking pressure generated in the brake chamber of the master brake cylinder to the wheel brakes when the brake pedal is depressed. The automatic brake operation mode involves supplying pressure in the accumulator to the wheel brakes irrespective of operation of the brake pedal by establishing fluid communication between the accumulator and the wheel brakes and interrupting fluid communication between the brake chamber of the master cylinder and the wheel brakes.
In addition, if the brake pedal is depressed while the brake apparatus is in the automatic brake operation mode, the wheel brakes are brought into fluid communication with the pressure chamber by the second valve so that in addition to the pressure in the accumulator applied to each wheel brake, the master cylinder pressure is applied to each wheel brake.
However, in this conventional brake apparatus, to obtain a braking pressure in the wheel brakes when the brake pedal is depressed during the automatic brake operation mode which is substantially equivalent to the braking pressure in the wheel brakes when the brake apparatus is in the normal operation mode, the amount of brake pedal depression (i.e., the brake pedal stroke) is smaller than that in the normal operation mode. These two different amounts of brake pedal depression for obtaining two equivalent or substantially equal braking forces may not provide a good braking feeling.
In light of the foregoing, a need exists for a hydraulic pressure brake apparatus which is able to provide a good braking feeling without the foregoing drawback.
SUMMARY OF THE INVENTION
In light of the foregoing, one aspect of the invention involves a hydraulic brake apparatus that includes a pressure source, a regulator for regulating pressure in the pressure source to a regulated pressure corresponding to the operation force of the brake pedal to supply the regulated pressure to a power chamber during operation of the brake pedal, a booster and a master cylinder. The regulator includes a pressure increasing valve which establishes and interrupts a fluid communication between the pressure source and the power chamber and a pressure decreasing valve which establishes and interrupts a fluid communication between the power chamber and a reservoir. The booster ha a power piston operated by the regulated pressure in the power chamber, and the master cylinder is associated with at least one wheel brake and interlocked with the booster. A valve member applies the pressure in the pressure source to the power chamber irrespective of operation of the brake pedal. The valve member includes a first valve establishing and interrupting a fluid communication between the power chamber and the pressure decreasing valve and a second valve establishing and interrupting a fluid communication between the power chamber and the pressure source.
According to another aspect of the invention, a hydraulic pressure brake apparatus includes a pressure source, a regulator that regulates pressure in the pressure source to a regulated pressure corresponding to the operation force of a brake pedal to supply the regulated pressure to a power chamber during operation of the brake pedal, a booster and a master cylinder. The regulator includes a pressure increasing valve which alternatively establishes and interrupts fluid communication between the pressure source and the power chamber and a pressure decreasing valve which alternatively establishes and interrupts fluid communication between the power chamber and a reservoir. The booster includes a power piston operated by the regulated pressure in the power chamber, and the master cylinder is associated with at least one wheel brake and is interlocked with the booster. The master cylinder has a master cylinder piston adapted to be interlocked with the power piston, and a pressure chamber defined between the master cylinder piston and the power piston. A valve mechanism applies the pressure in the pressure source to the pressure chamber irrespective of operation of the brake pedal to operate the master cylinder piston. The valve mechanism includes a first valve alternatively establishing and interrupting fluid communication between the pressure chamber and the pressure decreasing valve and a second valve alternatively establishing and interrupting fluid communication between the pressure chamber and the pressure source.
REFERENCES:
patent: 3877756 (1975-04-01), Inada et al.
patent: 4305624 (1981-12-01), Belart et al.
patent: 4768842 (1988-09-01), Ogino et al.
patent: 4815793 (1989-03-01), Reinartz et al.
patent: 4832418 (1989-05-01), Mattusch
patent: 4914917 (1990-04-01), Schonlau
patent: 5531509 (1996-07-01), Kellner et al.
patent: 6183049 (2001-02-01), Oka et al.
Nishii Michiharu
Oishi Masaki
Yamamoto Hideki
Aisin Seiki Kabushiki Kaisha
Burns Doane , Swecker, Mathis LLP
Ryznic John E.
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