HYDRAULIC PRESSURE MODULATOR FOR USE IN ADAPTIVE BRAKING SYSTEMS

• US 3,669,403 A
• Filed: 10/20/1969
• Issued: 06/13/1972
• Est. Priority Date: 03/13/1968
• Status: Expired due to Term

• Current Assignee: Siemens-Bendix Automotive Electronics LP
• Original Assignee: Michael Slavin, Ralph W. Carp
• Inventors: Slavin, Michael, Carp, Ralph W.
• Primary Examiner(s): Blix, Trygve M.
• Assistant Examiner(s): Kunin, Stephen G.
• Application Number:
  US04/867,840
• Time in Patent Office: 967 Days
• Field of Search: 188/181A,181C,181T 137/47,82,462,487.5,513.3 251/61,25,30,61.5 303/21,6,61
• US Class Current: 251/30.01
• CPC Class Codes: B60T 8/17633 based on analogue circuits or digital circuits comprised of discrete electronic elements
• CPC Class Codes: B60T 8/1764 Regulation during travel on surface with different coefficients of friction, e.g. between left and right sides, mu-split or between front and rear
• CPC Class Codes: B60T 8/425 using a vacuum

Abstract

A vacuum actuated hydraulic pressure modulator for use in an adaptive braking system for automobiles, trucks and the like, which is interposed in the vehicle hydraulic brake line between the master cylinder and the wheel cylinders to be controlled in response to error signals generated in an adaptive braking system control channel includes a diaphragm and a cooperating displacement rod within the modulator body which are positioned in accordance with the volumetric rate of air admitted to one side of the diaphragm by a solenoid valve which opens in response to an error signal generated by the adaptive braking system control channel when the vehicle wheels attain a certain dynamic condition. The displacement rod cooperates with a ball valve to normally allow free communication between the master cylinder and wheel cylinder; however, when the air is admitted through the solenoid valve in response to the error signal the displacement rod is displaced so as to isolate the wheel cylinders from the master cylinder and additionally to rapidly attenuate the hydraulic pressure at the wheel cylinders. In response to the decreasing brake pressure at the wheel cylinders, the wheel begins to accelerate to its vehicle speed. At another dynamic wheel condition, the error signal is extinguished thereby closing the solenoid valve. The modulated diaphragm and displacement rod are now repositioned so as to slowly increase the braking pressure, the rate of pressure increase being determined by the amount of air leakage across the modulator diaphragm. If wheel acceleration, in spite of the increasing brake pressure, increases to a third reference level, a modulator bypass valve is opened in response to a second control channel error signal so as to pneumatically shut the aforementioned diaphragm causing the displacement rod and diaphragm to be repositioned more rapidly, thus increasing the brake pressure at a more rapid rate, which rate is determined by the size of the bypass valve.

Claims

1. In a modulating means incluDing a flexible diaphragm means for dividing a first interior portion of said modulating means into first and second expansible chambers, means for normally urging said diaphragm means to expand said first chamber and contract said second chamber;

first valve means having at least two ports and cooperating with said diaphragm means for allowing communication between said two ports when said first chamber is expanded and for interrupting communication between said two ports when said second chamber is expanded;

a first chamber port for communicating said first chamber to sink for fluid;

valve means actuable for communicating said second chamber with a source of said fluid at a relatively high pressure to thereby cause said second chamber to expand;

an improvement comprising;

additional valve means independently actuable for providing, when actuated, substantially free communication between said first and second chambers for expanding said first chamber.

2. Modulating means as recited in claim 1 wherein said additional valve means includes leaky means providing at least continuous restricted communication for said fluid between said first and second expansible chambers.

3. Modulating means as recited in claim 1 with additionally means providing restricted communication between said first and second expansible chambers.

4. Modulating means as recited in claim 1 wherein said additional valve means comprises an electrical solenoid valve responsive to first and second electrical signals.

5. Modulating means as recited in claim 4 wherein said third valve means is opened to provide substantially free communication between said first and second expansible chambers when responsive to said first electrical signal and closed in response to said second electrical signal whereby only restricted communication between said first and second expansible chambers is provided by said restricted communication means.

6. Modulating means as recited in claim 1 wherein said fluid at relatively high pressure is atmospheric air and wherein said sink is a source of vacuum.