| 摘要 |
An improved position control apparatus is disclosed to control a motor-driven door operator to halt movement of a door at an open position and a closed position. The position control apparatus includes a control screw means in the form of a threaded shaft extension of the motor shaft or a threaded rod coupled to the motor shaft which is rotated when the motor is energized. A travel nut is threadedly engaged with the control screw means and is constrained against rotational motion so as to reciprocate along the control screw means. Position detection means, such as switches, are disposed near the control screw means for actuation by the travel nut to control the motor as the door approaches the open position and the closed position. In another embodiment, a toggle switch is mounted on the travel nut, and the switches are replaced by stops for actuation of the toggle switch to control the motor. An improved obstruction detector apparatus is also provided to control the motor if an obstruction is encountered as the door moves between the open position and the closed position. The obstruction detector apparatus includes a safety switch which is actuable by rotation of the motor casing due to reaction torque, if an obstruction is encountered as the door moves in one direction, and a lever that is actuable by rotation of the motor casing, if an obstruction is encountered as the door moves in an opposite direction, to actuate the safety switch.
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