| 摘要 |
PURPOSE:To keep vacuum pressure in a vaccum system to a constant level, by using a pressure sensor. CONSTITUTION:When the vacuum pressure in a vacuum pipe 2 is higher than a set value, the voltage outputted from the sensor 10 is increased, and when the vacuum pressure is low, the voltage outputted from the sensor 10 is reduced. In accordance with the output voltage from the sensor 10, pulse width is modulated. During the period that the modulated wave is kept at the ''1'' level, air is guided to the vacuum pipe 2. When the modulated wave is kept at ''0'' level, a diaphragm room is made negative pressure status by the vacuum pipe. The diaphragm room is rapidly controlled so as to be retured to the set up degree of vacuum. Since the pressure sensor part can be separated from the diaphragm room, the pressure can be measured precisely. |
