Apparatus for monitoring elevator brakes

摘要

An apparatus for monitoring an elevator brake includes at least one sensor and a monitoring circuit. The elevator brake has a rotating brake drum upon which a pair of brake shoes are pressed during braking. The sensor is embedded in a carrier which is mounted on the brake shoe and extends into a brake lining on the shoe. The sensor has a pair of connecting wires each formed into a generally U-shaped loop extending toward the brake drum. The sensor can be a temperature dependent resistor wherein the temperatures in the brake lining, caused by excessive braking processes, can be detected electrically. The thickness of the brake lining decreases due to wear until the brake drum connects the loops upon braking, whereby the sensor is short-circuited which condition can be detected electrically. In the case of brake lining breaks, an infinite resistance occurs between the connecting wires which can likewise be detected electrically. The sensor is connected to the monitoring circuit which employs a plurality of amplifiers connected to different reference voltage sources to convert the sensor signal into output signals representing brake conditions.