JPH0264429A - Measuring device of differential pressure - Google Patents

Abstract

PURPOSE:To enhance the sensitivity to a change in static pressure and thereby to enable accurate compensation of the static pressure by dividing fixed electrodes in a pair into two fixed electrodes of an equal area respectively, by calculating a static pressure signal on the basis of a prescribed operation formula and by using this signal. CONSTITUTION:When a measuring pressure is applied from the right and left of a main body 1, a measuring diaphragm 2 is displaced by a differential pres sure of the measuring pressure. Electrostatic capacities of the fixed electrodes and the diaphragm is changed differentially by this displacement and an electric signal output corresponding to the differential pressure is obtained. The fixed electrodes in a pair are parted therein into two fixed electrodes 61, 62, and 63, 64, having an equal area respectively. When the respective electrostatic capacities thereof are represented by CH1, CH2, CL1, CL2 and the static pressure signal by S, the operation formula of the static pressure signal is S=(CH1XCH2XCL1XCL2)/{(CH1+CH2)(CL1+CL2)}. According to this method, the sensitivity of the signal S to the static pressure is doubled, and thus the static pressure can be compensated accurately by using this signal.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a differential pressure measuring device that increases the sensitivity of the differential pressure measuring device to changes in static pressure and can accurately compensate for static pressure. .

<Prior Art> FIG. 4 is an explanatory diagram of the configuration of an imported example that has been commonly used in the past.

In the figure, 1 is a block-shaped main body made of metal.

11 is an internal chamber provided in the main body 1.

Reference numeral 2 denotes a measuring diaphragm which divides the internal chamber 11 into two measuring chambers 12 and 13 and functions as a moving electrode.

31.32 is the internal chamber 11 facing the measuring diaphragm.
These are fixed electrodes that are respectively provided on the walls of the walls through insulating materials 33 and 34.

41 is a metal ring for fixing the measurement diaphragm 2.

42 is a metal ring for connecting the main body 1.

43 is a ring-shaped housing into which the main body 1 and the like are inserted and fixed.

Reference numerals 51 and 52 denote wave-shaped seal diaphragms that are provided on both sides of the main body 1 and constitute the main body 1 and seal chambers 53 and 54.

55 and 56 are wave-shaped pack-up nests provided on the side surface of the main body 1 facing the seal diaphragms 51 and 52.

Reference numeral 14.15 denotes a communication hole that communicates the seal chamber 53.54 with the measurement point 12°13.

Reference numerals 101 and 102 are incompressible sealed liquids filled in two chambers each consisting of a measurement chamber 12.13, a communication hole 1415, and a seal chamber 53.54. In this case, silicone oil is used.

In the above configuration, when measuring pressures P, , P2 are applied from the left and right sides of the main body 1 in the figure, the measuring diaphragm 2 is displaced by the differential pressure of the measuring pressures P+P2. Measuring diaphragm 2
By the displacement of the fixed voltage fl! The capacitance between 31 and 32 and the measuring diaphragm 2 changes differentially, and an electrical signal output corresponding to the differential pressure is obtained.

<Problems to be Solved by the Invention> However, in such devices, static pressure is detected in order to compensate for static pressure errors.

As shown in Fig. 5, the measuring diaphragm 2 and the fixed electrode 3
If the capacitance with 1.32 is CH, CL, CH= (εA)/(d+x) CL=(εA>/(d-x) ε; dielectric constant A; area d of fixed electrode 31.32 : Measuring diaphragm 2 and fixed g 1m 31 .

32; the displacement signal S of the measuring diaphragm 2 is S= (CHXCL)/(CHICL)=(εA)/
(2d) This is the series capacitance of CH and CL and represents the capacitance between the fixed electrodes.

Further, since A and d are constant, the signal S becomes a function of the dielectric constant ε, and static pressure can be detected.

However, generally the fill liquid used is 101.10
In case of No. 2, since the change in dielectric constant with respect to static pressure is small, it is difficult to accurately detect static pressure.

That is, ε=ε. (1+α) ε0; Reference permittivity α: Change due to static pressure Then, α is small.

The present invention solves this problem.

An object of the present invention is to provide a differential pressure measuring device that is highly sensitive to changes in static pressure and can accurately compensate for static pressure.

Means for Solving the Problems> To achieve this object, the present invention includes a measuring diaphragm, a capacitor arranged opposite to the measuring diaphragm with the measuring diaphragm in between, and connecting the measuring diaphragm and a static capacitor to the measuring diaphragm. A differential pressure measuring device comprising a pair of fixed electrodes constituting electrodes and a sealed liquid filling a space between the fixed electrodes and the measuring diaphragm, wherein each of the pair of fixed electrodes is connected to two fixed electrodes. Equal area f,',
Let I\electronic capacitance be CHI and CH2.

CL + , CL2 and the static pressure signal is S, the calculation formula for the static pressure signal is S = (CH+
C1,.

XCl-2) / I (CH, +C
H2) (CLl しCL2)) A differential pressure measuring device is configured.

Effects> In the above configuration, when measurement pressure is applied from the left and right sides of the main body, the measurement diaphragm is displaced by the differential pressure between the measurement pressures. By displacing the 2N constant diaphragm, the capacitance between the fixed electrode and the measuring diaphragm changes differentially, and an electrical signal output corresponding to the differential pressure is obtained.

Thus, a pair of fixed electrodes each have an equal area of 2111, and each capacitance is CH.

C+-12, CL+, CL2, and the static pressure signal is S, the calculation formula for the static pressure signal is 5-(CH,XCH2XC
L, I XCL2 ) / ((CHt
+CH2) (CI-, +CI-2)), the static pressure can be accurately compensated based on this quiet pressure signal.

Hereinafter, a detailed explanation will be given based on examples.

<Example> FIG. 1 is an explanatory diagram of the main part of an embodiment of the present invention.

In the figure, the same symbols as in FIG. 4 represent the same functions.

Hereinafter, only the differences from FIG. 4 will be explained.

61, 62 and 63, 64, as shown in FIG. 2, each have two fixed electrodes having the same area instead of a pair of fixed electrodes.

In the above configuration, when measurement pressure is applied from the left and right sides of the main body 1, the measurement diaphragm 2 is displaced by the differential pressure between the measurement pressures. By the displacement of the measuring diaphragm 2, the fixed type trj! The capacitance between 31 and 32 and the measuring diaphragm 2 changes differentially, and an electrical signal output corresponding to the differential pressure is obtained.

Therefore, when a pair of fixed electrodes are respectively two fixed electrodes 61, 62, 63, and 64 of equal area, each capacitance is CHI, CH2, CLI, and Cl2, and the static pressure signal is S. The calculation formula for the static pressure signal is S= (CH7XC
H2XCLI XCl2 )/((CHI +CH2)
(CLI +Cl-2)), the static pressure can be accurately compensated based on this static pressure signal.

Now, as shown in Figure 3, CHI, CH2, CLCl,
2.

C1-I, = (εA+)/(d+x)CH2=(
ε A+)/(d+x) CH3= (εA+)/(d-x)CHa”
(εA+)/(dx) A + “l” A/2 (1) Differential pressure signal ΔP Since the displacement X of the measuring diaphragm 2, which is a moving electrode, is proportional to the differential pressure, if the displacement A pressure signal is obtained.

ΔP= (CLI +CL2 CHI CH2)/
(CLI +CL2 +CHI±CH2)-[(2ε
A+/(d x)) (2εA+/(d+x)
))]/ [+2εAI/ (d+x))+ +2ε
Since d is constant, it can be used as a differential pressure signal.

(2) Static pressure signal S.

The dielectric constant ε of the filled liquid changes when static pressure is applied.

ε=εo(1+α) ε. ; Reference permittivity α; Change due to static pressure S, = (CH+ X CH2X CL, X CL
2 )/((CHI +CL+)(CH2+CL
2)) = (ε'A,' / (d-1-x)(d-x))
2/[(εA+ / (d 1x) i +(εA+
/ (a-X) l]2 (εA + / 2 d) 2 (A+/2di fε. (1+α)) (εOA 1
/ 2 d ) 2 (1 + 2 a ) where (εo
A+/2d)' is constant.

As a result, since the fixed electrodes 31 and 32 were divided, the capacitance of each was halved, but the static pressure signal S had twice the sensitivity to static pressure compared to the static pressure signal S of the conventional example. It has become.

Using this static pressure signal S1, sensitivity to changes in static pressure can be increased and static pressure can be compensated accurately.

<Effects of the Invention> As explained above, the present invention includes one measurement diaphragm and a pair of electrodes arranged opposite to the measurement diaphragm with the measurement diaphragm in between and forming a capacitance electrode with the measurement diaphragm. In a differential pressure measuring device comprising a fixed electrode and a sealed liquid filling a space between the fixed electrode and the measuring diaphragm, each of the pair of fixed electrodes is formed into two fixed electrodes of equal area. , each capacitance is CH1, CH2゜Cl,, Cl
2, and when the static pressure signal is S, the calculation formula for the static pressure signal is S-(CH+X CH2X CI-XCL2)/
A differential pressure measuring device was constructed, characterized in that I (CH, +CH2) (CL+ 10 CL, 2)).

As a result, since the fixed electrodes were divided, each capacitance was halved, but the static pressure signal has twice the sensitivity to static pressure compared to the static pressure signal of the conventional example.

Using this static pressure signal, it is possible to increase the sensitivity to changes in static pressure and accurately compensate for static pressure.

Therefore, according to the present invention, it is possible to realize a differential pressure measuring device that can increase the sensitivity of the differential pressure measuring device to changes in static pressure and can accurately compensate for static pressure.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the main part configuration of an embodiment of the present invention, Fig. 2 is an explanatory diagram of the main part of Fig. 1, Fig. 3 is an explanatory diagram of the operation of Fig. 1, and Fig. 4 is a conventionally commonly used FIG. 5 is a diagram illustrating the operation of FIG. 4. 1... Main body, 101, 102... Filled liquid, 11...
・Inner room, 12.13...Measurement room, 14.15...
Communication hole, 2...Measuring diaphragm, 33.34...
Insulator, 41.42...Ring, 43...Housing, 51.52...Seal diaphragm, 53.54
... Seal chamber, 55.56 ... Bank up nest, 61,62°63.64 ... Fixed electrode.

Claims (1)

[Scope of Claims] A measuring diaphragm, a pair of fixed electrodes arranged opposite to the measuring diaphragm with the measuring diaphragm in between and forming a capacitance electrode with the measuring diaphragm, and the fixed electrodes In a differential pressure measuring device comprising a sealed liquid filled in a space between the measuring diaphragm and the measuring diaphragm, the pair of fixed electrodes are each two fixed electrodes of equal area, and each capacitance is CH_1, CH_2, CL_1
, CL_2, and the static pressure signal is S, the calculation formula for the static pressure signal is S=(CH_1×CH_2×CL_1×CL_
2)/{(CH_1+CH_2)(CL_1+CL_2
)}.