1、控制原理:将超声波发射机和接收机分设在巷道两边。当无车(或人)通过时,发射机发射的超声波信号,接收机正常收到,中间继电器不动作。当人或车通过时,挡住了超声波信号,接收机收不到信号,中间继电器动作,接通延时电路,再经延时继电器接通交流接触器使电机正转开门;人或车通过后,经8～12秒的延时,延时继电器释放,电机反转关门。 1, the control principle: the ultrasonic transmitter and receiver are located on both sides of the roadway. When no car (or people) passed, the transmitter ultrasonic signal transmitted, the receiver received normally, the middle relay does not move. When people or vehicles through, blocking the ultrasonic signal, the receiver does not receive the signal, the middle relay action, connected to the delay circuit, and then by the delay relay connected to the AC contactor to open the door to the motor; people or vehicles through , After 8 ~ 12 seconds of delay, the release of delay relay, motor reversal closed.