Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Reexamination Certificate
1999-08-02
2001-03-20
Schwartz, Christopher P. (Department: 3613)
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
C303S052000
Reexamination Certificate
active
06203119
ABSTRACT:
This invention relates to a brake system having a primary actuator responsive to an operator to effect a first brake application and a secondary actuator responsive to dynamic forces experience by a vehicle to effect a second brake application and attenuate the dynamic forces.
BACKGROUND OF THE INVENTION
In brake systems, it is common to use a hydraulic booster for supplying a master cylinder with an input force to effect a brake application such as disclosed in U.S. Pat. No. 5,120,115. When a traction control function is added to this type hydraulic booster in a manner as disclosed in U.S. Pat. No. 4,815,793, the total length may become an issue in a vehicle where under the hood space is limited. In order to reduce the overall length of this type hydraulic brake booster, it has been disclosed in U.S. Pat. No. 4,843,819 to use parallel boost pistons, which are connected to a master cylinder. However, when under the hood space is critical, a brake booster of the type disclosed in U.S. Pat. No. 4,514,981 has been used to control the supply of pressurized fluid to effect a brake application. These hydraulic brake boosters have satisfied many of the operational requirements of vehicle braking systems but space requirements and safety parameters continually limit the availability of current available brake boosters.
SUMMARY OF THE INVENTION
The present invention defines a hydraulic brake booster, which combines a reduction in the physical dimensions, and structure through which the speed of application can maintain the operational demands of a vehicle within an acceptable safety specification.
The hydraulic brake booster has a control apparatus through which pressurized fluid is supplied to wheel brakes by a primary actuation system acting in response to an operational input from an operator for effecting a first brake application and by a secondary actuation system means acting in response to a dynamic input derived from the operation of a vehicle for independently effecting a second brake application. The control apparatus has a housing with a first cylindrical member located in a first bore and a second cylindrical member located in a second bore. The first cylindrical member and a first valve seat member define a first chamber within the first bore while the second cylindrical member and a second valve seat member define a second chamber within the second bore. The first and second chambers are connected to a source of pressurized fluid. First valve means are located in the first chamber and second valve means are located in the second chamber. A first plunger means is resiliently positioned in the first bore and with the first valve seat member define a first brake chamber in the first bore. The first brake chamber is connected to a first portion of the brake system for the vehicle. A second plunger means is resiliently positioned in the second bore and with the second valve seat define a second brake chamber in the second bore. The second brake chamber is connected to a second portion of the brake system for the vehicle. The first plunger means includes a first stem through which the first brake chamber is connected with a reservoir while the second plunger means includes a second stem through which the second brake chamber is connected with the reservoir. An input means is connected to the first and second plunger means and is responsive to an input force for respectively moving the first and second stems into engagement with the first and second valve means to initially terminate communication between the first and second brake chambers and the reservoir. The input force acts on and further moves the first valve means with respect to the first valve seat member and the second valve means with respect to the second valve seat to allow metered pressurized fluid communication between the first chamber and the first portion of said brake system by way of the first brake chamber and between the second chamber and the second portion of the brake system by way of the second brake chamber to effect a brake application as the primary brake system of the vehicle. Many of the components in the primary brake system are also used in the secondary actuation system which is characterized by actuation means for independently moving the first and second valve seat members with respect to the first and second valve means in response to a dynamic input signal to initially interrupt communication through the first and second stems to the reservoir and thereafter initiating communication of metered pressurized fluid from the first and second chambers to the first and second portions of the brake system by way of the first and second brake chambers to effect a second brake application and attenuate a dynamic operation of the vehicle.
An advantage of the present invention resides in structure through which a valve seat is moved to effect a secondary actuation of a hydraulic brake booster and attenuate a dynamic condition experienced by a vehicle.
A further advantage of this invention resides in a parallel bore hydraulic brake booster having mutually exclusive primary and secondary actuation of control valves to selectively effect the actuation of wheel brakes of a vehicle.
A further advantage of this invention resides in a control having first and second valves rough which primary and secondary linkages respectively respond a manual input and a hydraulic input derived from a dynamic condition to effect a brake application in a vehicle.
REFERENCES:
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patent: 3927915 (1975-12-01), Adachi
patent: 4357055 (1982-11-01), Leiber et al.
patent: 4405183 (1983-09-01), Resch
patent: 4604870 (1986-08-01), Bach et al.
patent: 4653814 (1987-03-01), Burgdorf
patent: 4964676 (1990-10-01), Resch
patent: 5112115 (1992-05-01), Willmann et al.
patent: 5142865 (1992-09-01), Sakakihara et al.
Kosarski, Jr. Raymon
Mackiewicz John E.
McClain Richard Becker
Towers Kenneth Scott
Comstock Warren
McCormick Jr. Leo H.
Robert Bosch Corporation
Schwartz Christopher P.
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