Multiple-stage collision avoidance braking system and method

An automatic braking collision avoidance system, for a commercial vehicle air brake system, having a front brake circuit and a rear brake circuit, comprising:

• a collision warning device providing a signal representing closure time with a foregoing vehicle or object, including an impending collision warning signal and an imminent collision warning signal;
• a rear air pressure reservoir, and a front air pressure reservoir, where the pressure in said rear and front reservoirs is each maintained at the same pressure;
• an actuation apparatus element being electrically connected to said collision warning device for reacting to an impending collision warning signal and to an imminent collision warning signal;
• at least one connection element in a pneumatic pressure line between said rear air pressure reservoir and said rear service brake circuit, wherein said connection element operates as a valve;
• at least one connection element in a pneumatic pressure line between said front air pressure reservoir and said front service brake circuit, wherein said connection element operates as a valve;
• wherein when an impending collision warning signal is detected, said actuation apparatus first controls said rear air service brake pressure to pressurize said rear brake circuit such that when said rear brake pressure reaches a first threshold, said actuation apparatus controls said front air service brake pressure to pressurize said front brakes;
• wherein when the pressure at said rear brakes and the pressure at said front brakes each reach its predetermined target pressure, further pressure increases are ceased and the target pressures are maintained.

A method of automatic braking, collision avoidance for vehicle air brake systems, including the steps of:

• receiving a collision indication signal;
• pressurizing the rear brakes with a first higher pressure when said collision indication signal is detected;
• pressurizing the front brakes when the pressure at the rear brakes has risen to a first threshold value which is less than said first higher pressure, said pressurizing maintaining a pressure differential between a higher rear brake pressure and a lower front brake pressure;
• and
• maintaining an higher air pressure of at the rear brakes and a lower air pressure at the front brakes at said pressure differential, to slow or stop the vehicle.