Air brake pressure modulator

Claim 2

In a pneumatic brake system having antiskid means for sensing an impending wheel lock condition and the termination of said lock condition and an operator actuated control for delivering pneumatic pressure to the pressure actuated brake system associated with at least one wheel of a vehicle, a brake pressure modulator including a housing having inlet, outlet and exhaust ports adapted to communicate with said operator actuated control, said brake system and the atmosphere, respectively, valve means movable between a first position normally communicating said inlet port with said outlet port and isolating the latter from said exhaust port for delivering brake applying pressure to said outlet port and a second position communicating said outlet port with the exhaust port and isolating said inlet port to relieve brake applying pressure at said outlet port, actuator means to move said valve means in response to a signal of an impending wheel lock or termination of a wheel lock, additional valve means between said inlet port and said valve means and being movable by said valve means from an open to a closed position in response to movement of said valve means to said second position following a first signal of an impending wheel lock to isolAte said inlet port from said valve means, said additional valve means being maintained in said closed position in response to the presence of pressure in said inlet port, and metering valve means disposed between said inlet port and said outlet port, said metering valve means being movable from a closed to an open position by said first mentioned valve means when said additional valve means is in said closed position and in response to movement of said valve means to said first position upon termination of said wheel lock condition to communicate said inlet port and said outlet port for gradual increase of said brake applying pressure at said outlet port.

Claim 3

The combination set forth in claim 1 in which said housing forms a brake applying control chamber between said valve means and said additional valve means and in which said first named valve means and additional valve means are movable in response to said first signal of an impending wheel lock to isolate said brake applying control chamber from said outlet port and inlet port, and in which said first named valve means and said metering valve means are operative upon said termination of said wheel lock condition to communicate said brake applying control chamber with said outlet port for relatively rapid initial increase of brake applying pressure at said outlet and to communicate said brake applying control chamber through said metering valve means to said inlet port for a subsequently slower increase in brake applying pressure at said outlet port.

Claim 4

For use in a pneumatic brake system having means for sensing an impending wheel lock condition and the termination of said wheel lock condition, a brake pressure modulator including a housing having inlet, outlet and exhaust ports adapted to communicate with an operator controlled source of brake applying air pressure, with said brake system and with the atmosphere, respectively, said housing forming a brake applying control chamber between said inlet and said outlet ports and a brake release control chamber between said outlet port and exhaust port, first metering means between said inlet port and said brake applying control chamber, second metering means between said brake release control chamber and said exhaust port, valve means in said housing movable between a first position communicating said brake applying control chamber with said outlet port and closing the latter to said brake release chamber and a second position in which said outlet port is in communication with said brake release control chamber and is closed to said brake applying control chamber, actuator means to move said valve means from said first position to said second position in response to a signal of an impending wheel lock and from said second position to said first position upon termination of said signal, said valve means being movable to said second position for initial rapid decrease of brake applying pressure at said outlet port upon equalization of pressures in said outlet port and said brake release control chamber and subsequent gradual decrease of said brake applying pressure from said brake release control chamber through said second metering means to said exhaust port, said valve means being movable to said first position in response to the termination of said wheel lock condition for initial rapid increase of brake applying pressure at said outlet port upon communication of pressure in said brake applying control chamber with said outlet port and subsequent gradual increase in said brake applying pressure at said outlet port upon communication of the latter with said inlet port through said first metering valve means and said brake applying control chamber.

Claim 5

For use in a pneumatic brake system having means for sensing an impending wheel lock condition and the termination of said wheel lock condition, a brake pressure modulator including a housing having inlet, outlet and exhaust ports adapted to communicate with an operator controlled source of brake applying air pressure, with said brake system and with the atmosphere, respectively, said housing forming a brake applying control chamber between said inlet and said outlet ports and a brake release control chamber between said outlet port and exhaust port, first metering means between said inlet port and said brake applying control chamber, second metering means between said brake release control chamber and said exhaust port, valve means in said housing movable between a first position communicating said brake applying control chamber with said outlet port and closing the latter to said brake release chamber and a second position in which said outlet port is in communication with said brake release control chamber and is closed to said brake applying control chamber, actuator means to move said valve means from said first position to said second position in response to a signal of an impending wheel lock and from said second position to said first position upon termination of said signal, said valve means being movable to said second position for initial rapid decrease of brake applying pressure at said outlet port upon equalization of pressures in said outlet port and said brake release control chamber and subsequent gradual decrease of said brake applying pressure from said brake release control chamber through said second metering means to said exhaust port, said valve means being movable to said first position in response to the termination of said wheel lock condition for initial rapid increase of brake applying pressure at said outlet port upon communication of pressure in said brake applying control chamber with said outlet port and subsequent gradual increase in said brake applying pressure at said outlet port upon communication of the latter with said inlet port through said first metering valve means and said brake applying control chamber.

Claim 6

The combination set forth in claim 3 and further comprising additional valve means between said inlet port and said brake applying control chamber, said additional valve means normally being open and being movable to a closed position in response to movement of said first mentioned valve means to said second posItion to isolate said brake applying control chamber from said inlet, outlet and exhaust ports and maintain the pressure therein at a magnitude equal to the pressure at said inlet port when said signal of an impending wheel lock is received and until said first mentioned valve means is moved from said second position to said first position.

Claim 7

The combination set forth in claim 3 and further comprising additional valve means responsive to movement of said first named valve means to said second position and to brake applying air pressure at said inlet port to isolate the latter from said brake applying control chamber.

Claim 8

The combination set forth in claim 5 in which said first metering means includes a valve element movable with said first named valve means, said valve element being movable from a closed to an open position upon movement of said first named valve means from said second to said first position for restricted communication between said inlet port and said outlet port and for gradual increase in brake applying pressure.

Claim 9

The combination set forth in claim 3 in which said second metering means includes a resilient element forming an open passage between said brake release control chamber and said exhaust port and in which said resilient element deflects in response to pressure in said brake release control chamber to restrict the size of said passage.