| 摘要 |
<p>A pressure sensing probe having an elongated housing with an elastic diaphragm located at one end of the housing. The outer face of the diaphragm is substantially flush with the outer wall surface of the housing. An interior cavity is formed in the housing with at least a portion of the inner face of the diaphragm being in communication with the interior cavity. Also in communication with the interior cavity are a fluid supply port containing a flow-restricting supply orifice, a fluid output pressure port, and a fluid exhaust port containing a flow-restricting exhaust nozzle, each of which are formed in the walls of said housing. The diaphragm is normally biased inwardly by a biasing spring having its one end attached to an armature secured to the inner face of the diaphragm. The other end of the biasing spring is attached to an armature stem guide fixedly secured within the cavity of the housing which maintains the spring in constant tension. The armature also has a stem that passes downwardly within the biasing spring and through the armature stem guide. The lower end of the armature stem acts as a flapper which when the armature stem is raised and lowered varies the flow of fluid through the exhaust nozzle positioned beneath the flapper to control the amount of fluid passing outwardly through the fluid exhaust port. A fluid supply regulator is connected to the fluid supply port and a fluid exhaust regulator is connected to the fluid exhaust port in order to control the pressure of the fluid supplied through the orifice to the fluid cavity of the probe and to control the pressure of the fluid exhausted through the nozzle from the fluid cavity of the probe. The fluid output pressure port is also connected directly to each of the pressure regulators, thereby providing a pilot pressure for each of the regulators. The function of the probe is to reproduce exactly in fluid pressure the changes in the fluid pressure to which the sensing diaphragm is exposed. The probe output pressure reading will always be greater than the actual fluid pressure if the diaphragm is preset with an inward bias by the biasing spring. This probe biasing allows negative fluid pressures to be read out on the instrument as positive fluid pressures, thus enabling it to deal with negative heads of pressure.</p> |
