JPS61155829A - Pressure gauge - Google Patents

Abstract

PURPOSE:To eliminate a span shift by fuse-welding different kinds of materials at necessary temperatures, measuring a generated difference in strain and generating reference strain for the span of strain of necessary strain, and dividing resistance variation of a strain gauge due to measurement pressure by utilizing the reference strain. CONSTITUTION:A span reference strain mechanism 2 consists of the 1st, the 2nd, and the 3rd substrates 21, 22, and 23 and the 1st and the 2nd strain gauges 24 and 25, and the substrate 21 is divided into the 1st and the 2nd areas 212 and 213 by an insulating groove 211. The substrates 22 and 23 are fuse-welded to the areas 212 and 212 at necessary temperatures t1 and t2, and gauges 24 and 25 are arranged in the areas 212 and 213 respectively. Further, a pressure receiving mechanism 3 is applied with measurement pressure PS and the 3rd strain gauge 32 fitted to a diaphragm part 31 is fitted to a base 1 through the 4th substrate 33. Then, a subtracting circuit operates the difference between outputs of the gauges 24 and 25 and a dividing circuit divides the output of the gauge 32 by the output of the subtracting circuit, thus obtaining a pressure gauge which is not affected by temperature variation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pressure gauge using a strain gauge that does not undergo span shift due to temperature changes.

[Prior art]

Generally, it is difficult to create a standard for strain span that is independent of temperature. For example, as shown in FIG. 1, when an object made of 1m and 2a of different materials fused together is heated, distortion occurs. In this case, as shown in FIG. 2, the relationship between degree and strain changes to lj =a. The distortion formula is as follows. However, when t=1 (1, no distortion occurs).

-2=(αl-(fz) (t-to)g, : temperature t
Strain at K α1: Coefficient of expansion of 1 m of material α2: Coefficient of expansion of 2 m of material to: Strain greater than the fusion temperature of materials 1a and 2 m is used as a standard for the span of strain K.
must know the measured value at temperature t.

Therefore, temperature-dependent strain is inappropriate as a criterion for strain span.

[Purpose of the invention]

An object of the present invention is to create a reference strain of a strain span that is not subject to temperature disturbance, and to utilize this strain to provide a pressure gauge using a strain gauge without span shift.

[Structure of the invention]

To achieve this purpose, the ninth substrate is divided into a first region and a second region by a force insulating groove, and the second substrate and the second substrate are surface-bonded to the first region at a required temperature. a third substrate made of the same material as the second substrate and surface-bonded to the region at a required temperature; a first strain gauge disposed in the first region; and a second strain gauge disposed in the second region. With span reference strain mechanism.

a pressure receiving mechanism comprising a diaphragm section to which measurement pressure is applied and a third strain gauge attached to a cough diaphragm section KIII; a subtraction circuit for calculating a difference in output between the first strain gauge and the second strain gauge; , and a division circuit that divides the output of the third strain gauge by the output of the subtraction circuit.

Examples will be described below.

〔Example〕

Figures 3, 4, and 5 are explanatory diagrams of the main part configuration of an embodiment of the present invention. Figure 3 is a front view, and Figures 4 and 5 are detailed views of the main parts of Figure 3. be.

In the figure, 1 is a base, and 2 is a span reference strain mechanism mounted on the base. The span reference strain mechanism 2 includes a first substrate 21. Second substrate 22. The third substrate 23° consists of a first strain gauge 24 and a second strain gauge 25. The first substrate 21 is
In this case, it is divided into a first region 212 and a second region 213 by a glass-like insulation groove 211K.

The second substrate 22 is surface-bonded to the first region 212 at a required temperature t0. The third substrate 23 is surface-bonded to a second region 213 made of the same material as the second substrate 22 at a required temperature t2. The first strain gauge 24 is arranged in the first region 212K. The second strain gauge 25 is arranged in the second region 213. 3 is a pressure receiving mechanism attached to the pace IK. The pressure receiving mechanism 3 is used to apply measuring pressure, and in this case, a diaphragm portion 31 made of silicon and a diaphragm portion 3 are connected to each other.
1 attached to the third strain gauge 32. The diaphragm portion 31 is attached to the PACE IK, which is a subtraction circuit that calculates the difference in output between the first strain gauge 24 and the second strain gauge 25, which are made of silicon in this case. 5 is a division circuit that divides the output of the third strain gauge 32 by the output of the subtraction circuit.

In the above configuration, in order to manufacture the span reference strain mechanism 2, for example, the first strain gauge 24 and the third substrate 23tC'' second strain gauge 25 are formed in advance on the second substrate 22 by diffusion. The substrate 22 is fused to the first region 212 of the first substrate 21 by anodic bonding or the like.

Let us assume that the temperature in this case is heavy. Next, the third substrate 23 is fused to the second region 213 of the first substrate 21 by changing the temperature. The temperature in this case is assumed to be 1□.

The strain "tl" of the second substrate 22 is 1 = (α1-α,) (1-11) The distortion t2 of the third substrate 23 is 1 = (αl-α2) (t -11') α1; First substrate 21 Thermal expansion coefficient α2 of the second substrate 22, the thermal expansion coefficient of the third substrate 23, the first and second strain gauges 24. If the gauge factor of 25 is G, then the resistance change due to the strain described above is expressed by the following linear equations: Become.

When the above output is subtracted by the subtraction circuit 4, ΔRspan
=ΔRtl−ΔR12=GR(αl−α2)(tl−
1l)=GR&,, where '8p51°=(α1-α2)(12-11).

On the other hand, if the strain generated in the third strain gauge 32 due to the measurement pressure Pm is am, then the resistance change ΔRm of the third strain gauge 32 due to the measurement pressure car is 21m = GR also has a gauge factor of 01111 degrees, so it depends on the temperature. The sensitivity changes.

Considering ΔRm/ΔRspan as a pressure signal, ΔR
m/ΔR@span=aJ@span.

'5pan has no temperature coefficient. Then, Δ
The divided output of Rm/ΔRspan becomes a pressure signal without span shift.

As a result, a pressure gauge without span shift is obtained.

Note that in the above implementation, the second substrate 2 is attached to the first substrate 21.
2 and the third substrate 23 are fused together by anodic bonding or the like, but this is Kll! ! For example, it may be manufactured using vapor deposition or sputtering film growth.

Figure 7 (4) (B) shows an example of a plow K made by this method.

First, as shown in FIG. 7(4), the first strain gauge 24 and the second strain gauge 25 are formed at respective required positions on the first substrate 21 by diffusion. As shown in FIG. 7 φ), the second region 213 of the first substrate 21 is masked 2131.

A film is grown on the second substrate 22 in the first region 212 at a temperature t1.

Next, as shown in FIG. 7C, the first region 212 of the first substrate 21 is masked 2121, and the second region 213 is
A film is grown on the third substrate 23 at the temperature t2.

As described above, the span reference band mechanism 2 is manufactured.

[Function and effect of the invention]

As explained above, the present invention uses different materials.

They are heat-sealed at a required temperature tl+t2, and the difference in strain produced between them is taken to create a reference strain for a span of strain of a required magnitude. By using this reference strain and dividing the change in resistance of the strain gauge due to the measured pressure, a pressure needle that is not affected by temperature changes, that is, without span shift, is obtained.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the configuration of a conventional example commonly used, Fig. 2 is an explanatory diagram of Fig. 1, Fig. 3, Fig. 4, Fig. 5, and Fig. 6 are one embodiment of the present invention. This is an explanatory diagram of the configuration of the example. Figure 3 is a front view, Figures 4 and 5 are detailed views of the main parts of Figure 83, Figure 6 is an electrical circuit diagram, and Figure 7 (translation) 01) C) is It is a manufacturing explanatory drawing of another Example of this invention. l...Pace, 2...Span reference band mechanism, 21.
...First substrate, 211... Force insulation groove, 212...
First region, 213... Second region, 22... Second substrate, 23... Third substrate, 24... First strain gauge, 25
...Second strain gauge, 3...Pressure receiving mechanism. 31...Diaphragm part, 32...Third strain gauge,
33... Fourth board, 4... Subtraction circuit, 5... Division circuit. Figure 4, Figure 5, Figure 6, Figure 7 (A) (B) (C)

Claims (1)

[Claims] a first substrate divided into a first region and a second region by a force insulating groove; a second substrate surface-bonded to the first region at a predetermined temperature; and a second substrate surface-bonded to the second region at a predetermined temperature. A span reference strain mechanism includes a third substrate made of the same material as the second substrate, a first strain gauge disposed in the first region, and a second strain gauge disposed in the second region, and a measurement pressure is applied. a pressure receiving mechanism comprising a diaphragm portion and a third strain gauge attached to the diaphragm portion; a subtraction circuit for calculating a difference in output between the first strain gauge and the second strain gauge; A pressure gauge comprising a division circuit that divides the output by the output of the subtraction circuit.