| 摘要 |
713,045. Controllers. MOORHEAD, J. April 24, 1952, No. 10295/52. Class 38(3) [Also in Group XXV] A garage door is operated by an electric motor 5 adapted to be started by a switch 20, movement of the door being arranged to drive a rotary controller 14 which incorporates means for stopping the motor when the door is either fully open or fully closed, and also means for ensuring reversed operation of the motor when the latter is again started. The controller comprises two circular contacts 15, 16 formed integrally with respective substantially semi-circular, aligned contacts 15A, 16A, and a contact formed by two abutting discs 17, 18 each having a peripheral cut-off portion to provide straight edges 17A, 18A. The contacts are rotatable with a spindle 13 made from insulating material, the discs 17, 18, which constitute a limit switch, and which are electrically connected to contact 16, being rotatable relatively to each other to provide a circuit-breaking gap of variable length, and being secured to the spindle by a set screw 19. The switch 20 is connected to a ground plate set in the approaches to the garage, and is adapted to be successively opened and closed by the successive passing of a car wheel, over the ground plate. A second control switch 23 is provided either within or without the garage. The electrical mains are connected at 22 to the circuit and the latter comprises a junction box 21. A conductor A leads to the limit switch 17, 18, conductors B and E lead to the contacts 16 and 15 respectively, and conductors C and D to diametrically opposed points so as to be contacted in turn by the contacts 15A and 16A. The arrangement is such that, when the door is closed, switches 20, 23 and 17, 18 are open. The front wheels of a car approaching the garage depress the ground plate to close switch 20, when the motor starts in the door-opening direction: Switch 20 is opened by the back wheels of the car, but switch 17, 18 has in the meantime closed to maintain the motor in operation. When the door is fully open switch 17, 18 opens to stop the motor, the contacts 15A, 16A now having reversed their original positions so that the motor will next drive in the reverse direction to close the door, when required. |
