| 摘要 |
PURPOSE:To prevent a driver from biting, by decreasing torque of a pulse motor when it actuates a valve body to be moved to its full opening or full closing position. CONSTITUTION:An expansion valve 1 receives in the bottom part of its bellows 9 the low pressure acting after adiabatic expansion when a room is cooled while the high pressure acting before the adiabatic expansion when the room is heated. The expansion valve 1, if it is given a full closing signal, generates a locked condition in a valve body 8 by driving a pulse motor 10. Here a frequency corresponding to small torque is only enough for the frequency for driving the pulse motor 10 even in its valve closing direction because internal pressure of the bellows 9 decreases to a level lower than the pressure when the pulse motor is stopped. The expansion valve 1 can reduce vibration and noise while prevent also a driver 19 from biting into a bush 23 because the torque of the pulse motor is decreased when it actuates the valve body to its full closing locked position. |
