Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Reexamination Certificate
1999-10-28
2001-07-03
Butler, Douglas C. (Department: 3613)
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
C303S113100, C303S901000, C303S116100
Reexamination Certificate
active
06254200
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates in general to electronically controlled vehicular brake systems. In particular, this invention is concerned with a hydraulic control unit for a vehicular brake system having a control valve that controls fluid from a master cylinder to an inlet of a pump.
Electronically controlled vehicular brake systems may include anti-lock, traction control, and vehicle stability control functions. During various braking functions, such as vehicle stability control (VSC), a pump is activated to provide high-pressure fluid to a wheel brake. For certain events, the pump draws fluid from a master cylinder. A normally closed supply valve is positioned in a hydraulic connection between the master cylinder and an inlet to the pump. During a various braking events, the supply valve is opened so that the pump draws fluid from the master cylinder.
During a vehicle stability control event, a driver may have applied the brake pedal, thereby pressurizing fluid in master cylinder. The VSC supply valve must be able to open under such relatively high-pressure situations so that fluid can be drawn to the pump and supplied to wheel brakes.
SUMMARY OF THE INVENTION
This invention relates to electronically control vehicular brake systems and a control valve for such systems. The present control valve is particularly adapted for a supply valve in a brake system having a vehicle stability control function. The control valve opens as desired under both high master cylinder pressure conditions and low master cylinder pressure conditions.
In a preferred embodiment, a hydraulic control unit of a vehicular brake system includes a housing having a bore formed therein. A normally closed solenoid valve is retained in the bore of the housing. The solenoid valve includes a primary valve and a pilot valve, wherein a cross section of the primary valve is greater that a cross section of the pilot valve. A spring cooperates with the pilot valve so that the pilot valve is open when the primary valve is open.
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patent: 4782862 (1988-11-01), Nguyen
patent: 5810330 (1998-09-01), Eith et al.
patent: 5865213 (1999-02-01), Scheffel et al.
patent: 5882090 (1999-03-01), Ganzel
patent: 34 22 214 C2 (1984-12-01), None
patent: 44 41 150 A1 (1996-05-01), None
patent: 219118 (2000-08-01), None
Butler Douglas C.
Kelsey-Hayes Company
MacMillian Sobanski & Todd, LLC
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