Valve module for an air braking system of a heavy vehicle

A valve module for a vehicle having a compressed air supply, a driver demand device for providing a driver demand pressure indicative of driver intent to apply brakes, one or more brake chambers, and a controller for controlling delivery of air flow through the valve module to the one or more brake chambers to control an autonomous braking event of the vehicle, the valve module comprising:

• a relay valve having a control port, a supply port, and a delivery port, wherein (i) the supply port of the relay valve is connectable in fluid communication with the compressed air supply, and (ii) the delivery port of the relay valve is connectable in fluid communication with the one or more brake chambers;
• a first solenoid valve having a first solenoid, at least one supply port, and a delivery port connected in fluid communication with the control port of the relay valve, wherein the first solenoid is responsive to a first electrical signal from the controller to deliver a first control pressure from the driver demand device through the first solenoid valve to the control port of the relay valve to control air flow from the supply port of the relay valve through the relay valve to the delivery port of the relay valve to control air flow to the one or more brake chambers;
• and
• a second solenoid valve having a second solenoid, at least one supply port, and a delivery port, wherein (i) the second solenoid is responsive to a second electrical signal from the controller to deliver a second control pressure to the first solenoid valve to combine with the first control pressure, and (ii) the combined first and second control pressures are applied to the control port of the relay valve to control air flow from the supply port of the relay valve through the relay valve to the delivery port of the relay valve to control air flow to the one or more brake chambers and thereby to control the autonomous braking event of the vehicle;
• wherein the first solenoid valve comprises an activatable 3/2 valve that, when activated in response to the first electrical signal from the controller, moves from a first position in which air is blocked from flowing through a first supply port of the first solenoid valve and air is allowed to exhaust from the control port of the relay valve through the first solenoid valve through the second solenoid valve to atmosphere to a second position in which air is allowed to flow from both the first and second supply ports of the first solenoid valve through the first solenoid valve to the control port of the relay valve.