Trailer detection control for vehicle central tire inflation system

Claim 1

A tow vehicle and trailer selectively attached to and detached from each other, the vehicle and trailer each including rotatably mounted tire assemblies having tire chambers, and an on-board tire pressure control system comprising: an air source mounted on the vehicle and providing pressurized air at a pressure greater than normally maximum tire chamber pressure; a wheel valve including an outlet port continuously communicating with a tire chamber of at least one of the trailer tire assemblies, an inlet port and a valving means movable between positions blocking and unblocking air communication between the ports in response to an absence and a presence of pressurized air at the inlet port; first conduit means mounted on the vehicle and having a predetermined volume for passage of air therethrough; first valve means mounted on the vehicle for allowing and blocking flow of the air source pressurized air to a first end of the first conduit means in response to receiving open and closed signals, respectively; second conduit means mounted on the trailer and having a predetermined volume for passage of air therethrough, and having a first end connected to the wheel valve inlet port; a disconnect valve including first and second parts respectively affixed to a second end of the first and second conduit means, the first and second parts operative when connected together to fluidly interconnect the volumes of the first and second conduit means, and when disconnected, the first part operative to block the second end of the first conduit means; sensing means providing pressure signals representive of air pressure in the first conduit means; a control circuit including means operative to activate a pressure check mode of the tire chamber pressure including applying a momentary open signal to the first valve means to effect the presence of a predetermined pressure level of pressurized air at the wheel valve inlet port to effect movement of the valving means to the unblocking position and thereby allowing air pressure in the first and second conduit means to equalize with the tire chamber pressure, activating inflation or deflation modes respectively in response to a pressure signal from the sensing means indicating a tire chamber pressure less than or greater than a preselected tire pressure, the inflation mode for connecting the air source with the tire chamber to increase tire chamber pressure and the deflation mode for connecting the tire chamber to a vent to decrease tire chamber pressure; and the control circuit further including inflation and deflation mode prevention means, said prevention means including means for applying a timed open signal to the first valve means for a predetermined time period sufficient to effect a first manifold pressure in the first conduit means when both of the first and second parts of the disconnect valve are connected and to effect a second manifold pressure when the first and second parts of the disconnect valve are disconnected wherein the first manifold pressure is different from the second manifold pressure, and stop means for preventing the activation of inflation and deflation modes for the trailer tire chamber in response to the pressure signal from the sensing means indicating the presence of the second pressure in the manifold.