Abstract A valve operator includes an electric motor moving the valve in one direction and working against a spring which moves the valve in the other direction. The energizing circuit for the motor includes an on-off switch and a temperature-dependent semiconductor. The semiconductor is connected to provide graduated energization of the motor during one of the valve movements. In one embodiment the semiconductor is in parallel with the switch and has a positive temperature coefficient. In another embodiment the semiconductor is in series with the switch and has a negative temperature coefficient. In the latter embodiment a second switch is in parallel with the semiconductor and this switch is normally open, but is closed after the motor is energized and upon its moving the valve to the fully open position.
In an apparatus comprising a valve actuated by an electric motor working against a spring and an energizing circuit connected to said motor with a switch in said circuit in series with the motor so that when said switch is actuated to the closed position, after being open, said motor is energized to move the valve in one direction and when said switch is actuated to the open position, after being closed, said valve is moved in the other direction by the spring the improvement comprising: means connected in said circuit for retarding the valve movement upon the opening of said switch, said means comprising a temperature-dependent semiconductor having a positive temperature coefficient connected in parallel with said switch whereby when the switch is closed the semiconductor carries little current due to the switch forming a short circuit across it and the semiconductor develops a relatively low resistance and when the switch is thereafter opened the semiconductor increases in temperature and resistance from its initially low resistance as a consequence of the current flow through it.
Claim 2
Dependent Claim
176 words
In an apparatus comprising a valve actuated by an electric motor working against a spring and an energizing circuit connected to said motor with a switch in said circuit in series with the motor so that when said switch is actuated to the closed position, after being open, said motor is energized to move the valve in one direction and when said switch is actuated to the open position, after being closed, said valve is moved in the other direction by the spring the improvement comprising: means connected in said circuit for retarding the valve movement upon the opening of said switch, said means comprising a temperature-dependent semiconductor having a positive temperature coefficient connected in parallel with said switch whereby when the switch is closed the semiconductor carries little current due to the switch forming a short circuit across it and the semiconductor develops a relatively low resistance and when the switch is thereafter opened the semiconductor increases in temperature and resistance from its initially low resistance as a consequence of the current flow through it.