| 摘要 |
An ambient pressure sensor generates an electrical signal which varies in response to changes in ambient pressure level. The sensor includes a sealed bellows or aneroid which varies in length as the ambient pressure varies. A fluid motor including a piston slidably mounted within the housing carries a tube which extends to a position adjacent one end of the aneroid. The end of the tube defines a valve seat which cooperates with a valve member carried on the end of the aneroid to control communication of atmospheric pressure through the tube and into the power chamber defined between the piston and the end of the housing. The power chamber is connected with a vacuum source, so the atmospheric pressure communicated through the tube varies the pressure level in the power chamber as a function of ambient atmospheric pressure, since the aneroid controls communication through the tube. Consequently, the piston and tube move relative to the housing as the ambient pressure changes. A potentiometer includes a wiper which is carried by the tube. The wiper is moved along a resistance within the potentiometer, to thereby generate an electrical signal which varies depending upon the position of the tube. |
