Emergency bypass for brake pressure control

Claim 2

A pressure modulating valve comprising a housing having an inlet port and an outlet port, a bore extending between said inlet port and said outlet port, a differential area piston slidably disposed in said bore, said differential area piston maintaining increases in outlet port pressure less than increases in inlet port pressure under normal operating conditions when said inlet port pressure exceeds a predetermined pressure, and solenoid means on said housing having coil means and core means for rendering said pressure modulating valve inoperable under abnormal operating conditions.

Claim 3

A pressure modulating valve as defined in claim 1 wherein said solenoid means includes means to block movement of said differential area piston under said abnormal operating conditions.

Claim 4

A pressure modulating valve as defined in claim 1 including valve means operable by said differential area piston to hydraulically isolate said inlet port from said outlet port under normal operating conditions when said inlet port pressure exceeds said predetermined pressure, and said solenoid means prevents operation of said valve means under said abnormal operating conditions.

Claim 5

A pressure modulating valve as defined in claim 1 including eLectrical connector means for electrically connecting said solenoid means to a warning switch for actuation of said coil means under said abnormal operating conditions, and said solenoid means rendering said pressure modulating valve inoperable only when said coil means is actuated.

Claim 6

In a motor vehicle dual hydraulic brake system, the combination of a first brake circuit, a second brake circuit, a warning switch for actuating an alarm device in response to a predetermined pressure differential between said first and second circuits, a pressure modulating valve in said first circuit, said pressure modulating valve including a housing having an inlet port and an outlet port, means in said housing for maintaining increases in outlet port pressure less than increases in inlet port pressure when said inlet port pressure exceeds a predetermined pressure, said warning switch being disposed forwardly of the fire wall of said motor vehicle and said pressure modulating valve being disposed remote from said warning switch and rearwardly of said fire wall of said motor vehicle, with emergency control means operable by said warning switch for rendering said pressure modulating valve inoperable in the event of a fluid pressure failure in said second circuit.

Claim 7

In a motor vehicle dual hydraulic brake system, the combination of a first brake circuit, a second brake circuit, a warning switch for actuating an alarm device in response to a predetermined pressure differential between said first and second circuits, a pressure modulating valve in said first circuit, said pressure modulating valve including a housing having an inlet port and an outlet port, means in said housing for maintaining increases in outlet port pressure less than increases in inlet port pressure when said inlet port pressure exceeds a predetermined pressure, said warning switch being disposed forwardly of the fire wall of said motor vehicle and said pressure modulating valve being disposed remote from said warning switch and rearwardly of said fire wall of said motor vehicle, with emergency control means operable by said warning switch for rendering said pressure modulating valve inoperable in the event of a fluid pressure failure in said second circuit.

Claim 8

A combination as defined in claim 5 wherein said emergency control includes a solenoid on said housing, said solenoid having a coil and a movable core, means electrically connecting said warning switch and said coil so that said warning switch completes an electrical circuit through said coil to energize said coil in response to said predetermined pressure differential, and said solenoid rendering said pressure modulating valve inoperable when said coil is energized.

Claim 9

A combination as defined in claim 6 wherein said movable core includes stop means for blocking movement of said differential area piston when said solenoid is energized.

Claim 10

A combination as defined in claim 6 including a first valve element in said bore, a second valve element carried by said differential area piston for engaging said first valve element to hydraulically isolate said inlet port from said outlet port and maintain increases in outlet port pressure less than increases in inlet port pressure, and said first valve element is moved by said solenoid to a position remote from said second valve element when said solenoid is energized.

Claim 11

A combination as defined in claim 5 wherein said warning switch includes two outlet ports for supplying brake fluid to the front wheel brakes of said motor vehicle, and said pressure modulating valve is disposed adjacent the rear axle of said motor vehicle and includes two outlet ports for supplying brake fluid to the rear wheel brakes of said motor vehicle.

Claim 12

A pressure modulating valve comprising a housing having an inlet port and an outlet port, a bore extending between said inlet port and said outlet port, a differential area piston slidably disposed in said bore, said differential area piston being spring biased to a first position in said bore, said differential area piston moving from said first position and maintaining increases in outlet port pressure less than increases in inlet port pressure under normal operating conditions when said inlet port pressure exceeds a predetermined pressure, and stop means for blocking said movement of said differential area piston for rendering said pressure modulating valve inoperable under abnormal operating conditions.

Claim 13

A pressure modulating valve comprising a housing having an inlet port and an outlet port, a bore extending between said inlet port and said outlet port, a differential area piston slidably disposed in said bore, said differential area piston being spring biased to a first position in said bore, said differential area piston moving from said first position and maintaining increases in outlet port pressure less than increases in inlet port pressure under normal operating conditions when said inlet port pressure exceeds a predetermined pressure, and stop means for blocking said movement of said differential area piston for rendering said pressure modulating valve inoperable under abnormal operating conditions.

Claim 14

In a motor vehicle dual hydraulic brake system, the combination of a first brake circuit, a second brake circuit, a warning switch for actuating an alarm device in response to a predetermined pressure differential between said first and second circuits, a pressure modulating valve in said first circuit, said pressure modulating valve including a housing having an inlet port and an outlet port, differential area piston means in said housing, said differential area piston means being spring biased to a first position and being movable from said first position for maintaining increases in outlet port pressure less than increases in inlet port pressure when said inlet port pressure exceeds a predetermined pressure, said warning switch being disposed forwardly of the fire wall of said motor vehicle and said pressure modulating valve being disposed remote from said warning switch and rearwardly of said fire wall of said motor vehicle, with emergency control means operable by said warning switch for blocking said movement of said differential area piston and rendering said pressure modulating valve inoperable in the event of a fluid pressure failure in said second circuit.

Claim 15

In a motor vehicle dual hydraulic brake system, the combination of a first brake circuit, a second brake circuit, a warning switch for actuating an alarm device in response to a predetermined pressure differential between said first and second circuits, a pressure modulating valve in said first circuit, said pressure modulating valve including a housing having an inlet port and an outlet port, differential area piston means in said housing, said differential area piston means being spring biased to a first position and being movable from said first position for maintaining increases in outlet port pressure less than increases in inlet port pressure when said inlet port pressure exceeds a predetermined pressure, said warning switch being disposed forwardly of the fire wall of said motor vehicle and said pressure modulating valve being disposed remote from said warning switch and rearwardly of said fire wall of said motor vehicle, with emergency control means operable by said warning switch for blocking said movement of said differential area piston and rendering said pressure modulating valve inoperable in the event of a fluid pressure failure in said second circuit.