RU2034254C1 - Semiconducting pressure gauge - Google Patents

Abstract

FIELD: measuring equipment. SUBSTANCE: semiconducting pressure gauge has housing 1 with prechamber 2 and separating diaphragm 3. Passage 4 connects prechamber 2 with measuring chamber 5 covered with diaphragm 6 having rigid center 7 whereto semiconducting diaphragm 8, coupled with an external measuring device via leads 9, is secured. Rigid center 7 is pressed to the wall of measuring chamber 5. Flexible diaphragm 6 is torus-like. Inserts 10, made of a material exhibiting a small change in volume as a function of temperature, is inserted in housing 1 and decreases volume of the working fluid. EFFECT: enhanced accuracy. cl, dwg

Description

 The invention relates to measuring technique, namely to high-precision pressure measurement using miniature semiconductor pressure transducers, protected from pressure overload.

 Closest to the invention is an overload protected semiconductor pressure transducer, comprising a housing filled with a working fluid with a prechamber located therein with a separation membrane, a measuring chamber in communication with the prechamber and a closed elastic membrane with a semiconductor sensitive element located on its rigid center.

 However, this device has a measurement error associated with the imperfection of the elastic properties of the separation and elastic membranes, as well as in connection with a change in the volume of the working fluid with temperature.

 The technical result obtained from the invention is to reduce the error introduced by the liquid overload protection device.

 The essence of the invention lies in the fact that in the semiconductor pressure transducer the elastic membrane is installed in a prestressed state, while the rigid center of the elastic membrane is pressed against the housing with an initial force exceeding the force created by the working fluid at the maximum measured pressure.

 The elastic membrane can be made with a toroidal surface.

 An inserted insert made of a material with a temperature coefficient of expansion lower than that of the material of which the housing is made can be installed in the measuring chamber.

 In FIG. 1 shows a diagram of a semiconductor pressure transmitter; in FIG. 2 the same with the insert; in FIG. 3 structural design of the Converter; in FIG. 4 constructive solution of its measuring unit.

The semiconductor pressure transducer comprises a housing 1 with a pre-chamber 2, in which the working fluid is separated from the measured medium by a separation membrane 3. Channel 4 connects the pre-chamber 2 with the measuring chamber 5, closed by an elastic membrane 6 with a rigid center 7, on which a semiconductor membrane 8 is connected, connected by current leads 9 with measuring equipment (not shown). The rigid center 7 is pressed against the wall of the measuring chamber 5 with some initial force F _about .

Work transducer (FIG. 1) is that the measured pressure P _and the pressure P creates a working fluid, which membrane 8 deforms and modifies the parameters of its strain-sensing elements. When exceeding the measured pressure P _{and the} preset value P _of the force acting on the elastic membrane 6, the force F is equalized _on pressing its center to the housing 1. Further the pressure increase _{P, and} as a result in the displacement of the elastic membrane 6, and the separation membrane 3. After as the pressure reaches a certain value of P _and = P _cr , the separation membrane 3 lies on the body, blocking the channel 4, and with a further increase in pressure P _{and the} pressure of the working fluid P does not change, which protects the semiconductor membrane 8 from destruction.

The pressure of the working fluid P is less than the measured pressure P _and by a certain value Δ P = P _and -P. The value of Δ P depends on the stiffness K of the separation membrane 3 and the displacement δ of its center: Δ P = K x δ The displacement is determined by the change Δ V of the volume of the measuring chamber 5, arising due to the deformation of the elastic membrane 6 under the influence of pressure R. Change in the volume of the measuring liquid filled with liquid cameras 5 with a fixed center 7 is approximately 4 times smaller than with a moving center. This allows to reduce the measurement error associated with the elastic imperfections of the membranes 3 and 6.

In the case of the elastic membrane 6 to the toroidal corrugations (FIG. 2) the change in volume of the measuring chamber 5 _and the pressure P is further reduced (with a fixed hard center 7).

 The temperature error is reduced when the volume of the measuring chamber 5 is minimized due to the insert 10 inserted into the housing 1 (Fig. 2), since the insert 10, while the total volume of the pre-chamber 2, channel 4 and measuring chamber 5 remains unchanged, reduces the volume of the working fluid.

 Thus, the use of the invention in liquid protection devices of miniature semiconductor pressure transmitters can improve measurement accuracy.

Claims (3)

 1. SEMICONDUCTOR PRESSURE TRANSDUCER, overload protected, comprising a housing filled with working fluid with a prechamber located therein with a separation membrane, a measuring chamber in communication with the prechamber and a closed elastic membrane with a semiconductor sensitive element located on its rigid center, characterized in that the elastic membrane is installed in a prestressed state, while the rigid center of the elastic membrane is pressed against the body with an initial force exceeding force generated by hydraulic fluid at the maximum measured pressure.  2. The Converter according to claim 1, characterized in that in it the elastic membrane is made with a toroidal surface.  3. The Converter according to claim 2, characterized in that it contains an inserted insert made of a material with a temperature coefficient of expansion lower than that of the material from which the housing is made.

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