JPS6061637A - Composite function type differential pressure sensor - Google Patents

Abstract

PURPOSE:To obtain a differential pressure signal free from statical pressure and temperature effects, by correcting an output signal from a differential pressure detecting means by an output signal from statical pressure detecting means and temperature detecting means. CONSTITUTION:When pressures P, P+DELTAP are applied on to both sides of a thinned portion 11 of a sensor substrate 10 respectively, a group of differential pressure detecting semiconductor gauge resistances 111 detects a differential pressure DELTAP and its signal is applied to an A/D convertor 20. On the other hand, a statical pressure detecting semiconductor gauge resistance 131 of a thinned part 13 detects the statical pressure P and further, a temperature detecting semiconductor gauge resistance 141 of a thinned part 14 detects the temperature and each signal is applied to the A/D convertor 20. The A/D convertor 20 delivers these signals to CPU30 after A/D conversion to perform the required computation and thus, effects of the statical pressure P is eliminated from CPU30 and further, a differential signal proportional only to the differential pressure DELTAP with correction of effects by temperature T is issued.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a multifunction type differential pressure sensor, and particularly to a multifunction type differential pressure sensor suitable for obtaining a temperature-compensated differential pressure signal free from static pressure effects. It relates to a differential pressure sensor.

[Background of the invention]

There are many examples of differential pressure sensors that detect differential pressure and temperature. FIG. 1 is a longitudinal cross-sectional view showing an example of the basic structure of a currently used differential pressure transmitter. A semiconductor gauge resistor group 111 sensitive to differential pressure Δp is formed on the thin wall portion 11 of the silicon diaphragm 1, and a semiconductor gauge resistor 121 sensitive to temperature is formed on the fixed thick wall portion 12 by a diffusion method. These gauge resistors are made insensitive to high static pressure P, and are connected to an external circuit via a lead wire group 4 from a pressure-tight airtight terminal 3 provided in the housing 2, respectively. Therefore, a differential pressure Δp% can be obtained from the semiconductor gauge resistor group 111, a signal proportional to the temperature T can be obtained from the semiconductor gauge resistor 121, and a temperature-compensated differential pressure signal can be obtained from the external circuit.

However, the static pressure P applied to both sides of the recon diaphragm 1 of the differential pressure transmitter is usually as high as 100 atmospheres or more, which may cause irregularities in the amount of contraction of the liquid filled in the chambers 5 and 5' on both sides, and deformation of the housing 2. Since the silicon diaphragm 1 is deformed, the resistance 11σ of the semicircular gauge resistance group 111 changes accordingly. Therefore, the static pressure signal is superimposed on the differential pressure signal, making it impossible to obtain an accurate differential pressure signal. In other words, it is affected by static pressure, resulting in an error. In order to prevent this static pressure error, it is necessary to ensure that the liquid fillers in the chambers 5 and 5' are exactly aligned, and the housing 2f must be made of a material with high rigidity so that it will not be deformed by the static pressure P. However, this was a major constraint in design and manufacturing, and was an obstacle to miniaturization and cost reduction of differential pressure transmitters.

[Object of the Invention] The present invention has been made in view of the above, and its object is to be able to generate an accurate differential pressure signal that is free from static pressure effects and is temperature compensated, and to An object of the present invention is to provide a multifunctional differential pressure sensor that can be made smaller.

[Summary of the invention]

A feature of the present invention is that a differential pressure detection means for detecting differential pressure, a static pressure detection means for detecting static pressure, a temperature detection means for detecting temperature, and output signals from each of the above detection means are extracted from one housing. A means is provided to correct the output signal from the differential pressure detecting means by the output signals from the static pressure detecting means and the temperature detecting means to obtain a differential pressure (No. 6) that is free from static pressure and temperature effects. The point is that the configuration does not include calculation means.

[Embodiments of the invention]

The present invention will be explained in detail below using the embodiments shown in FIGS. 2 to 4.

FIG. 2 is a longitudinal cross-sectional view showing an embodiment of the basic structure of the multifunction type differential pressure sensor of the present invention, and shows the case of a semiconductor gauge type differential pressure transmitter. In Figure 2, 10 is a Senna substrate (silicon diaphragm) made of silicon single crystal.
The fixed thick portion 12 of the sensor board 10 is hermetically fixed to the housing 2 as shown. Reference numeral 3 denotes a glass pressure-resistant and airtight terminal provided on the housing 2, which reads signals from each gauge resistor provided on the sensor board 1O, which will be described later. 4 It is taken out to the outside through fc. Seal diaphragms 6.6' are airtightly fixed to both sides of the housing 2 at their outer peripheries.
Within the range of 5°5′ divided into two parts by the sensor board 10, there is a
1.1 human fluids such as oil are the size of a publication. Reference numeral 7.7' denotes a flange that sandwiches the housing 2 for applying differential pressure Δp and static pressure P to the sensor board 10.

The central part of the sensor substrate 1o is a thin walled part 11, and there is a pressure difference between the filled liquid in the chambers 5.5' on both sides, that is, a differential pressure Δ.
A semiconductor gauge resistor for differential pressure detection that converts the deformation into an electric signal is formed by gold diffusion on the thin part 11, and a thin film lead terminal 111a is further deposited by vapor deposition. It is. In addition, as shown in the figure, a part of the outer peripheral fixed thick part 12 of the sensor board 1o is processed into a groove shape from the fixed side to form a thin part 13, and the static pressure (absolute pressure) is detected on the upper surface of the thin part 13. The semiconductor gauge resistor 131 for use is formed by diffusion, and the thin film lead terminal 1
31a was deposited. In this case, the space 132 is filled with vacuum or air at atmospheric pressure to prevent the filled liquid from entering, so the gauge resistor 131 measures the filled liquid Ω pressure (÷ static pressure) in the chamber 5'. . In addition, the other part of the outer periphery fixed thick part] 2 of the sensor board 1o is processed from the outer periphery as shown in the figure to form a thin part 14, and a semiconductor gauge resistor 141 for temperature detection is placed on the upper surface of the thin part 14 by diffusion. Then, thin film lead terminals 141a are deposited. The reason why the wall portion 14 is made thin is to reduce the heat capacity and to prevent the housing 2 from being affected by deformation due to static movement, and also because the space 142 is communicated with the chamber 5'. When the thin portion 14 bends under the static pressure P and the differential pressure Δp, no deformation occurs.

Note that when forming a gauge resistor by diffusing boron, which is a p-type impurity, into a silicon single crystal plate with a (100) plane, the gauge resistor is formed along the <100> axis where the piezoresistance coefficient is almost zero. By arranging them, even if a slight deformation is transmitted, it will not appear as an electric signal, so the semiconductor gauge resistor 141 for temperature detection is formed in this way.

The casing 2 to which the sensor substrate 10 is fixed is made of a material such as glass having a coefficient of thermal expansion close to that of silicon.

FIG. 3 is a configuration diagram showing an embodiment of the detection signal processing flow of the multifunctional differential pressure sensor of the present invention.

A pressure P is applied to both sides of the thin wall portion 110 of the sensor substrate 10, respectively.
IP+ΔP), the differential pressure detection semiconductor gauge resistor group 111 detects the differential pressure ΔP, and the signal is sent to the lead terminal 1.
11a, and input to the A-D converter 20 via the lead wire 4a. On the other hand, semiconductor gauge resistor 1 for static pressure detection in thin wall portion 13
31t, the static pressure P is detected, and the [semiconductor gauge grinding resistor 141 for crystallinity detection in the thin wall portion 14] detects the temperature T.
and convert these signals into A-111 CI) U 3
0, the CPU 30 performs the necessary calculations, and the CPU
30, the influence of static pressure P is removed, and the temperature becomes r.
A differential pressure signal that is accurately proportional to only the differential pressure ΔP corrected for the influence of Reference numeral 40 denotes a memory that stores data and calculation programs necessary for calculations by the CPU 30.

- The above-mentioned differential pressure signal is displayed on the display device it, 50, and is also transmitted to others after being converted to D-A/& by the I)-A converter 60. In addition, by providing a separate switching device 1 value, in addition to the differential pressure 1 which is exactly proportional only to the differential pressure ΔP, the static pressure P
It goes without saying that it is possible to display and transmit a signal proportional to temperature T or temperature T. Furthermore, disturbance correction of the differential pressure signal may be performed.

According to the embodiment of the present invention described above, (1) It is possible to obtain an output proportional to the differential pressure -P in which the static pressure error caused by the deformation of the housing 2 due to the static pressure P is completely corrected.

(2) When the ambient temperature T changes, the characteristics of the gauge resistors 111 and 131 that detect differential pressure ΔP and static pressure P change, but since temperature compensation can be performed using the output of the semiconductor gauge resistor 141 for temperature detection, the temperature In addition to an output that is exactly proportional to only the unaffected differential pressure ΔP, it is possible to obtain an output that is proportional to the static pressure P.

(3) Each semiconductor gauge resistor 111, 131, 141 can be formed by the same semiconductor process, and the thin wall processing of the sensor substrate 10 uses semiconductor microfabrication technology! 1 can be easily performed, and the differential pressure sensor can be made smaller.

FIG. 4 is a sectional view of a main part showing another embodiment of the present invention.

In FIG. 2, differential pressure ΔP and static pressure P.

Although hand gauge resistors were used to detect the temperature 'P, in FIG. 4 these are replaced by capacitance sensors. In FIG. 4, 100 is a sensor substrate made of an elastic material such as silicon single crystal, 101, 10
Reference numeral 2 denotes a fixing plate made of virex glass having a coefficient of thermal expansion close to that of silicon that holds the sensor substrate 100, and the fixing plates 101 and 102 each hold the sensor substrate 1.
Thin film deposited electrodes 1011 and 1021 and lead wires 1012 and 1022 from these are embedded in opposing positions on both sides of the thin wall portion 100″1 for differential pressure detection of 00, and between the thin wall portion 1001 and the electrodes 1011 and 1021. , there are pressure guiding ports 1013 provided on the fixed plates 101 and 102, respectively.
1023, the pressure P, (P+ΔP) is derived. Further, a thin wall portion 1002 for detecting static pressure (absolute pressure) is formed on the right side of the sensor board 100, and pressure introduced from a pressure guiding port 1013 is applied to one side of the thin wall portion 1002, and the other side is heated. One side is vacuum ('-!i or atmospheric pressure).

A thin film deposition electrode 1024 and a lead wire 1025 from the thin film electrode 1024 are embedded in a portion of the fixed plate 102 facing the thin plate 1002. 1003 is a lead wire connected to the sensor board 100. Therefore, lead wires 1003 and 101
A capacitance change occurs between lead wires 1003 and 1022 in response to differential pressure ΔP, and a capacitance change occurs in response to static pressure P between lead wires 1003 and 1025. =&Fζ,
Since the dielectric constant of the liquid sealed between the electrodes 1011 and 1021 and the thin part 1001 changes depending on the temperature, this can be used to generate a temperature signal 't (4I).
With the configuration shown in FIG. 4, -C can also obtain the same effect as in the case of FIG. 2.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to obtain an accurate differential pressure signal that is free from static pressure effects and is temperature compensated, and moreover, it is possible to achieve miniaturization.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view showing an example of the principle structure of a conventional differential pressure transmitter, and FIG. FIG. 3 is a configuration diagram showing one embodiment of the detection signal processing flow of the multifunctional barley pressure sensor of the present invention, and FIG. 4 is a new music diagram of the main part showing another embodiment of the present invention. 2...Housing, 5.5'...M, 6.6'...7-
Diaphragm, 7.7'...Flange, 10...
Sensor board, 11, 13. 14... Thin wall part, 12...
・Fixed thick part, 111... 1-piece gauge resistance group for differential pressure detection, 131... Semiconductor gauge for static pressure detection, 141
...Temperature 1st figure 2nd mouth 3rd hardness 4th figure 1gume

Claims (1)

[Claims] 1. Differential pressure detection means for detecting differential pressure in one housing. A static pressure detection means for detecting static pressure, a temperature detection means for detecting temperature, and a means for extracting output signals from each of the detection means are provided, and the output signal from the differential pressure detection means is transmitted to the static pressure detection means. and a correction calculation means for correcting the output signal from the temperature detection means to obtain a differential pressure signal free from static pressure and temperature effects. 2. Each of the above-mentioned detection means is a group of semiconductor gauge resistors for differential pressure detection formed on the upper surface inside the central part of a diaphragm made of a silicon single crystal whose thick outer peripheral part is fixed to a housing described by F+iJ, respectively. A semiconductor gauge resistor for static pressure detection is formed on the upper surface of a thin wall part formed by processing the inner part of the thick wall part into a groove shape from the fixed side, and a shaped gauge resistor is formed by processing another part of the outer thick wall part from the outer periphery. A multifunctional differential pressure sensor according to claim 1.