Ultrasonic Brake Wear Sensors

Abstract

Brake wear sensors for the brake disc stacks commonly used in aircraft brake systems are disclosed. An ultrasonic transducer is employed to transmit signals to a reflective surface and to receive the reflected signals in return. The time that elapses between the transmission of the ultrasonic signal and the reception of its reflection correlates with the separation between the transducer and the reflective surface. The reflective surface is operatively connected to a pressure plate of the associated brake disc stack such that, as the stack wears, the reflective surface is displaced along with the pressure plate. That displacement correlates with brake wear. In one embodiment, the ultrasonic brake wear detector is an independent unit mounted to the brake housing, while another embodiment includes the detector as an integral portion of a brake actuator connected to such housing. A third embodiment for use with brake disc stacks exhibiting substantial wear before requiring service employs either twin cylinders, one with a piston and the other a wear pin, or a single cylinder housing a wear pin operatively fixed to the brake disc stack.

Dependencies are inferred from the claim text.