Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Reexamination Certificate
1999-03-10
2001-11-20
Oberleitner, Robert J (Department: 3613)
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
C303S116100
Reexamination Certificate
active
06318816
ABSTRACT:
This application is based on and claims priority under 35 U.S.C. §119 with respect to Japanese Application No. 10(1998)-57884 filed on Mar. 10, 1998, the entire content of which is incorporated herein by reference.
FIELD OF THE INVENTION
The present invention generally relates to a braking system. More particularly, the present invention pertains to a vehicle brake apparatus.
BACKGROUND OF THE INVENTION
Unexamined Published Japanese Patent Applications (Kokai) Nos. 58-39551 and 63-64858 disclose known vehicle brake apparatus that include a brake pedal, a wheel cylinder, a pressure source and a master cylinder. When the pressure source is in the normal condition, the pressure source supplies hydraulic braking pressure to the wheel cylinder in response to operation of the brake pedal. On the other hand, if the pressure source cannot supply hydraulic braking pressure to the wheel cylinder, for example if the pressure source is broken, the master cylinder supplies hydraulic braking pressure to the wheel cylinder. These known apparatus are further defined by an electromagnetic valve which includes a solenoid. The electromagnetic valve is disposed between the master cylinder and the wheel cylinder. The electromagnetic valve is constructed to establish, when the solenoid is deenergized, communication between the master cylinder and the wheel cylinder. When the solenoid is energized, communication between the master cylinder and the wheel cylinder is prevented. As a result, when the pressure source supplies hydraulic braking pressure to the wheel cylinder, the solenoid of the electromagnetic valve is energized to cut off communication between the master cylinder and the wheel cylinder.
However, in the above-described brake apparatus, if the brake pedal is operated for a long period of time to maintain a standstill condition of the vehicle, the solenoid of the electromagnetic valve is also continuously energized for a long period of time. Thus, the electromagnetic valve must be constructed to handle the electricity and so the electromagnetic valve become expensive.
It is possible to address this drawback by constructing the electromagnetic valve so that communication between the master cylinder and the wheel cylinder is prevented when the solenoid is deenergized and to establish communication between the master cylinder and the wheel cylinder when the solenoid is energized. However, the disadvantage here is that communication between the master cylinder and the wheel cylinder cannot be established if the electromagnetic valve is broken and the master cylinder cannot supply hydraulic braking pressure to the wheel cylinder.
In light of the foregoing, a need exists for a vehicle brake apparatus that is not as susceptible to the same disadvantages and drawbacks as those described above.
SUMMARY OF THE INVENTION
In accordance with one aspect of the present invention, a vehicle brake apparatus includes a brake pedal, a wheel brake cylinder operatively mounted on a wheel for applying a braking force to the wheel in proportion to a hydraulic braking pressure, a pressure source for pressurizing brake fluid to generate a hydraulic braking pressure and supply the hydraulic braking pressure to the wheel brake cylinder, and an auxiliary pressure source for pressurizing brake fluid in response to operation of the brake pedal to generate a hydraulic braking pressure and supply the hydraulic braking pressure to the wheel brake cylinder when the pressure source is non-operational. A mechanical valve is operatively mounted between the wheel brake cylinder and the auxiliary pressure source. A first passage is connected between the auxiliary pressure source and the mechanical valve and a second passage is connected between the mechanical valve and the wheel brake cylinder. The mechanical valve permits brake fluid communication between the first and the second passages when the pressure in the first passage is less than a predetermined pressure, and permits brake fluid to flow from the first passage to the second passage when the pressure of the first passage is more than the predetermined pressure.
According to another aspect of the invention, a vehicle brake apparatus includes a brake pedal, a wheel brake cylinder adapted to be operatively mounted on a wheel for applying a braking force to the wheel, a pressure source for pressurizing brake fluid to generate a hydraulic braking pressure and supply the hydraulic braking pressure to the wheel brake cylinder, and an auxiliary pressure source for pressurizing brake fluid in response to operation of the brake pedal to generate a hydraulic braking pressure and supply the hydraulic braking pressure to the wheel brake cylinder when the pressure source is non-operational. A mechanical valve is operatively mounted between the wheel brake cylinder and the auxiliary pressure source, and a first passage connects the auxiliary pressure source to the mechanical valve while a second passage connects the mechanical valve to the wheel brake cylinder. The mechanical valve is designed to permit communication between the first passage and the second passage when a pressure differential between the first passage and the second passage is more than a predetermined pressure, and permits brake fluid flow from the first passage to the second passage when a pressure differential between the first passage and the second passage is less than the predetermined pressure.
REFERENCES:
patent: 4957330 (1990-09-01), Morikawa et al.
patent: 5358320 (1994-10-01), Fuchida
patent: 5664849 (1997-09-01), Burgdorf et al.
patent: 5961188 (1999-10-01), Sawada
patent: 58-39551 (1983-03-01), None
patent: 63-64858 (1988-03-01), None
Aizawa Hiroaki
Kusano Akihito
Toda Hiroshi
Aisin Seiki Kabushiki Kaisha
Burns Doane , Swecker, Mathis LLP
Oberleitner Robert J
Torres Melanie
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