Fluid-pressure and analogous brake systems – Multiple fluid-receiving devices – Multiple motors
Patent
1982-05-03
1985-01-01
Stoner, Jr., Bruce H.
Fluid-pressure and analogous brake systems
Multiple fluid-receiving devices
Multiple motors
188349, B60T 1300
Patent
active
044913710
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a hydraulic pressure control valve for an automobile brake mechanism, and more particularly to a hydraulic pressure control valve which is disposed in an automobile braking system between its master cylinder and brake units to regulate a braking force for brakes of front and rear wheels. This invention is especially applicable for the rear brake units which is not equipped with a y-seal subject to hydraulic pressures from both sides thereof, unlike in the prior art, but are capable of partly restoring a braking force by inhibiting a plunger from moving in a direction in which to cut off a brake liquid upon failure of a liquid passage leading to each brake unit of either the front or rear wheels.
BACKGROUND OF THE INVENTION
In an automobile speed control mechanism, a braking force is usually converted by a hydraulic braking system into a hydraulic pressure of a brake liquid for transmission to each brake unit. With the hydraulic braking system, a force applied thereto from a brake pedal during braking is converted by a master cylinder into hydraulic pressure, which is further converted to hydraulic pressure suitable for the braking force of each of front and rear wheels and then transmitted to a wheel cylinder of each wheel to actuate its brake unit, thus braking the wheel.
For reducing the speed of an automobile, a large braking force is needed; in addition, its deceleration is limited by a value dependent upon an adhesion coefficient between tires and the ground. It is required that the braking force for the front and rear wheels be properly distributed by selecting a maximum oil pressure on a rear wheel brake smaller than on a front wheel brake. It is well-known in the art that an ideal distribution of the braking force for the front and rear wheels is such that the front brake gradually works with an increase in the braking force therefor, that is, the individual braking forces for the front and rear wheels bear such a relation as is represented by a quadratic curve. But the braking forces for the front and rear wheels are usually fixed, or bear a constant relation to each other, and a variety of hydraulic pressure control valves are employed for achieving such an ideal distribution of the braking force.
With such hydraulic pressure control valves, an input oil pressure from the master cylinder is usually transmitted, as it is, to the brake unit of, for example, the front wheel, whereas, to the brake unit of the rear wheel, the input oil pressure is applied after being reduced by a reciprocating motion of a plunger. These prior art valves are defective as discussed below. FIGS. 1(a) and (b) are a cross-sectional view of a conventional hydraulic pressure control valve and an enlarged view of one portion. As shown in FIG. 1, a valve proper 7 has formed therein brake liquid inlet ports 1 and 3 and outlet ports 2 and 4. A liquid passage from the inlet port 1 to the outlet port 2 constitutes a first hydraulic pressure passage leading to each brake unit of the front wheel, for instance, and a liquid passage from the inlet port 3 to the outlet port 4 constitutes a second hydraulic pressure passage leading to the brake unit of the front wheel, for example. In the central portion of the valve proper 7 is made a stepped hole 12a, in which a stepped plunger 5 is provided so that it may freely reciprocate. One end 5a of the plunger 5 partly extends into the first hydraulic pressure passage separated by a y-seal 6 from the second hydraulic pressure passage.
The other end 5b of the plunger 5 lies in the second hydraulic pressure passage, and a valve flange 5c of a larger diameter than that of the other end 5b is formed between the one end 5a and the other end 5b of the plunger. Further, a spring receiving flange 5d is formed in contact with the valve flange 5c, defining therebetween a circular space 5e. A spring 7a is supported by the spring receiving flange 5d and, by a plug 12 threadably engaged with the valve proper, the spring 7a is urged toward the firs
REFERENCES:
patent: 4311345 (1982-06-01), Schopper
Kadota Shinkichi
Yamase Tsuyoshi
Oberley Alvin
Rhythm Motor Parts Manufacturing Company Limited
Stoner Jr. Bruce H.
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