JPH06251671A - Pressure sensor structure - Google Patents

Abstract

PURPOSE:To give a good assembly property and improve the function and production yield by installing a pressure reception unit which senses the pressure of a pressure liquid, a sensor unit which is a sensor block, and a signal processing unit. CONSTITUTION:A pressure sensor has a pressure reception unit A which senses the pressure of a pressure liquid and a plunger 23 which operates corresponding to the pressure the unit A senses and a differential type sensor part 18 composed of two fixed electrodes 26, 30, and a movable electrode 28 is installed wherein the movable electrode is insulated and held between the electrodes 26, 30 and moves by pushing up the plunger 23. Moreover, a sensor unit B and a signal processing unit C are installed wherein the sensor unit B has a reference part 20 composed of mutually separated fixed electrodes 32, 34 and the signal processing unit C processes the electrostatic capacity of the differential sensor part 18 and a reference part 20 and sends out a desired signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure sensor structure for detecting the pressure of a fluid (gas or the like) and outputting a signal according to the pressure.

[0002]

2. Description of the Related Art As a conventional pressure sensor of this type, there is a technology disclosed in Japanese Patent Laid-Open No. 59-171826.
This disclosed technology attempts to compensate the temperature by matching the temperature coefficients of the housing, the diaphragm, and the spacer. The diaphragm supporting the movable electrode by soldering is fixed to the housing made of a metal material by soldering. The annular spacer made of a plastic material is fixed to the housing with screws, and the iron plate as a fixed electrode is fixed with screws so as to face the movable electrode.

As a conventional pressure sensor of this type, there is a technique disclosed in Japanese Utility Model Laid-Open No. 63-20039. This disclosed technique has a sensor structure in which a connecting body that pushes the movable electrode is provided in the center of the diaphragm, and a lead wire is taken out from the movable electrode.

[0004]

However, in the case of the technique disclosed in JP-A-59-171826, since the movable electrode is soldered to the diaphragm, the material of the diaphragm is limited, Is limited. In addition, special equipment for soldering is required for production, resulting in poor mass productivity. In terms of performance, since it is composed of a pair of movable and fixed electrodes, deterioration of sensor linearity due to parasitic capacitance is unavoidable, and in order to obtain this linearity, microcomputer correction for one product is required. It is necessary and cannot be used for applications that require a system. Also,
Since the humidity cannot be corrected, there is a problem that it cannot be used for industrial purposes.

In the case of the technique disclosed in Japanese Utility Model Laid-Open No. 63-20039, there is a problem similar to the technique disclosed in the above document, and the lead wire is taken out from the movable electrode. Therefore, the assemblability was poor, and when a negative pressure was applied, excessive stress was applied to the central part of the diaphragm, resulting in performance change or destruction.

The present invention has been made by paying attention to the above-mentioned problems, and the first object thereof is that it is excellent in assemblability and can be individually inspected, and therefore the performance yield is also good. In addition, it is possible to correct the absolute value of the characteristic by circuit processing and eliminate the need for complicated processing such as origin correction during use, and to provide a pressure sensor structure having sensor linearity that is not easily affected by temperature and humidity. Especially.

A second object of the present invention is that one-way assembly is possible, mass productivity is excellent, automation is possible, and no special construction method is required, so investment can be suppressed. An object is to provide an inexpensive pressure sensor structure.

A third object of the present invention is that the stopper shape for the diaphragm can be accurately set to improve the pressure resistance, and the output performance can be varied by exchanging the diaphragm. It is to provide a pressure sensor structure that can be used for various purposes (pressure specifications).

A fourth object of the present invention is to ensure the performances of the differential type sensor section and the reference section only by the thickness accuracy of the insulating film, requiring no special material and being inexpensive. It is to provide a pressure sensor structure that can be configured.

A fifth object of the present invention is to provide a pressure sensor structure which improves the sensor linearity.

[0011]

In order to achieve the above first object, the present invention provides a pressure receiving unit for detecting the pressure of a pressure fluid, and a fixed electrode and a pressure receiving unit that moves according to the pressure detected by the pressure receiving unit. In addition, a sensor unit having a differential sensor unit composed of a movable electrode insulated and held between fixed electrodes and a reference unit composed of fixed electrodes separated from each other, and a capacitance of the differential sensor unit and the reference unit are processed. And a signal processing unit for outputting a desired signal. Further, the pressure receiving unit may be provided with a metal bellows in the pressure receiving portion, or the reference portion of the sensor unit may be formed of an element having a fixed capacitance such as a capacitor.

In order to achieve the above second object, the present invention provides a pressure sensor structure according to claim 1, wherein the pressure receiving unit has a base for accommodating the sensor unit, and the sensor unit is a signal processing unit. The sensor unit is housed in the base of the pressure receiving unit, and the signal processing unit is housed in the electrode holder of the sensor unit.

In order to achieve the above third object, the present invention provides a pressure sensor structure according to claim 1, wherein the pressure receiving unit has a diaphragm detachably accommodated in the base, and the diaphragm is provided. It is characterized in that it has a flat surface perpendicular to the displacement direction, and a stopper portion is provided at a portion facing the flat surface of this diaphragm.

In order to achieve the above-mentioned fourth object, the present invention provides, in the pressure sensor structure according to claim 1, a member for insulating and holding a movable electrode in a differential type sensor section of a sensor unit, and a reference section. The member for separating the two fixed electrodes from each other is made of an insulating film.

In order to achieve the above fifth object, the present invention is characterized in that, in the pressure sensor structure according to claim 1, the differential type sensor portion of the sensor unit is of a variable area type. .

[0016]

According to the structure of claim 1, the pressure receiving unit that receives pressure, the sensor unit that determines the performance, and the signal processing unit are included in the unit unit, so that the assembling is excellent and the performance yield can be obtained because they can be individually inspected. Also, since the reference unit is built in and the absolute value of the characteristic can be corrected by circuit processing, complicated processing such as origin correction during use becomes unnecessary. Also. Since the sensor unit employs the differential type sensor structure, the sensor linearity is hardly affected by temperature and humidity.

Further, according to the second aspect of the invention, each unit can be assembled in one direction, which is excellent in mass productivity and can be automated. In addition, a special construction method is not required, investment can be suppressed, and an inexpensive sensor structure can be provided.

According to the third aspect of the invention, in the pressure receiving unit, the diaphragm has the flat surface perpendicular to the displacement direction, and the stopper shape can be set accurately, so that the pressure resistance performance can be improved. Also, since the output performance can be changed by replacing the diaphragm, it can be used for many applications (pressure specifications).

Further, according to the structure of claim 4, since the performance of the differential type sensor section and the reference section can be secured only by the thickness accuracy of the insulating film, no special material is required and the cost can be reduced.

According to the structure of claim 5, the linearity of the sensor is further improved.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical sectional view of a pressure sensor structure according to the present invention, and FIG. 2 is a perspective view of the pressure sensor structure in an exploded state. The pressure sensor structure according to the present invention is roughly divided into a pressure receiving unit A which is a pressure receiving block, a sensor unit B which is a sensor block, and a signal processing unit C which is a signal processing block.

The pressure receiving unit A comprises a base 1, an O-ring 2, a diaphragm 3 and a diaphragm retainer 4. The base 1 has a circular accommodating portion 5 in a plan view, and a bottom portion 5a of the accommodating portion 5 has a plurality of concentric stopper portions (negative pressure stoppers) 6a centered on the center of the bottom portion 5a. , 6b, 6c and an O-ring fitting groove portion 7 which is located outside the stopper portion 6c and is concentric therewith. Further, a concave portion 8 is formed on the bottom surface portion 5a in the radial direction from the center thereof, and the concave portion 8 is formed.
Communicates with the connecting pipe portion 9 formed on the peripheral surface of the base 1 so as to project therefrom, and these constitute the inflow port 10.

The diaphragm 3 is made of metal and is in the shape of a plate having a mounting portion 3b on the peripheral portion of the surface portion 3a as shown in FIGS. 3 to 5, and a plunger receiving portion 11 is formed in the central portion thereof. On the surface portion 3a of the diaphragm 3, there are projecting portions 12a, 12b, 12c, 12d protruding downward (in FIG. 5) in an annular shape around the plunger receiving portion 11,
A projecting portion 13 that is located outside the projecting portion 12d and is convex upward is formed, and the upper surface side of the surface portion 3a is a flat surface excluding the projecting portion 13.

The diaphragm retainer 4 is the base 1
Is formed into a circular shape in a plan view so that it can be inserted into the circular accommodating portion 5, and a bottom outer surface thereof is a flat stopper portion (positive pressure stopper) 14, and a hole portion 15 is formed at the center of the stopper portion 14. Is formed.

The O-ring 2 is fitted in the O-ring fitting groove portion 7 of the housing portion 5 of the base 1, and the diaphragm 3 and the diaphragm retainer 4 are housed therein.
The diaphragm retainer 4 presses the mounting portion 3b on the peripheral portion of the diaphragm 3 to fix the diaphragm 3, and the diaphragm 3 includes a bottom face portion 5a of the accommodating portion 5 and a stopper portion 14 of the diaphragm retainer 4. This diaphragm chamber 16 is located in the defining diaphragm chamber 16.
The pressure receiving side of is communicated with the inflow port 10.

The sensor unit B includes an electrode holder 1
7, a differential sensor unit 18, a spacer 19, a reference unit 20, and an electrode retainer 21. A holding hole 22 is formed in the center of the electrode holder 17, and a plunger 23 as a movable body is movably held in the holding hole 22. An electrode receiving portion 24 is formed on the bottom of the electrode holder 17, and a plurality of terminal insertion grooves 25 are formed on the inner peripheral surface of the electrode holder 17.

The differential sensor section 18 includes one fixed electrode 26 having a disk shape, one insulating film 27 having a ring shape, a movable electrode 28 having a disk shape, and the other insulating film 2 having a ring shape.
9 and the other fixed electrode 30 having a disk shape, and the fixed electrodes 26, 30 and the movable electrode 28 are provided with terminal portions 26a, 30a, 28a, respectively. A hole 31 is formed in the center of one of the fixed electrodes 26, and the movable electrode 28 has a holding portion 28b at its periphery and a movable portion 28c at the center, which is movable with the holding portion 28b. A plurality of slits 28d are formed in the circumferential direction between the movable portion 28c and the portion 28c.
c is retained.

The reference portion 20 is provided with one fixed electrode 32 having a disc shape, an insulating film 33 having an annular shape, and the other fixed electrode 34 having a disc shape.
Terminal portions 32a and 34a are formed on the reference numerals 2 and 34, respectively.

The electrode retainer 21 has a retainer 3 at the bottom thereof.
5 and a signal processing unit accommodating portion 36 at the upper part thereof, and a plurality of terminal holes 37 are formed in the peripheral portion of the signal processing unit accommodating portion 36.

In the electrode holder 17, one fixed electrode 26, one insulating film 27, movable electrode 28, the other insulating film 29, and the other fixed electrode 30 of the differential sensor section 18 are provided. Are stacked in this order, and the movable electrode 28 has its pressing portion 28b sandwiched from above and below by insulating films 27 and 29, and the terminal portions 26a, 30a and 28a are the inner peripheral surface portions of the electrode holder 17. Is inserted in the terminal insertion groove 25 of.

In the electrode holder 17, a spacer 19, a fixed electrode 32 of the reference unit 20, an insulating film 33, and a fixed electrode 34 of the other side are housed in the electrode holder 17 so as to overlap with each other. Fixed electrode 32,
The terminal portions 32 a and 34 a of 34 are inserted into the terminal insertion grooves 25 of the inner peripheral surface portion of the electrode holder 17. Then, in the electrode holder 17, the electrode holder 2 is stacked on the differential sensor unit 18, the spacer 19 and the reference unit 20.
The first holding portion 35 is inserted, and the terminal portions 26a, 30a, 28a, 32a, 34a project from the terminal hole 37 of the electrode holding member 21 toward the signal processing unit accommodating portion 36.

The sensor unit B configured as described above is accommodated in the accommodating portion 5 of the base 1 of the pressure receiving unit A, and one end (lower end) of the plunger 23 is accommodated.
Is in contact with the plunger receiving portion 11 of the diaphragm 3, and the other end (upper end) of the plunger 23 is in contact with the movable portion 28c of the movable electrode 28 from below.

The signal processing unit C has a substrate 38 having a shape that can be fitted in the signal processing unit accommodating portion 36, and the substrate 38 has the gate array 103 and the pulse output circuit 104 shown in FIG. 6 incorporated therein. ing.

The signal processing unit C is housed in the signal processing block housing portion 36 of the electrode retainer 21, and the terminal portions 26a, 30a, 28a, 32a, 34 are housed therein.
a is connected to the corresponding connection portion of the substrate 38.
A cover 39 is covered over the electrode retainer 21, the cover 39 is fixed to the base 1 by a screw 40, and lead wires 41, 4 connected to the substrate 38 are connected.
2, 43 are led out of the cover 39. in this case,
The lead wires 41, 42, and 43 are the electrode retainer 21 and the cover 39.
Is sandwiched between the protrusions 44 and 45 provided on the
The lead wires 41, 42, 43 have a large pull-out strength.

In the sensor unit B, the differential sensor portion 18 composed of the two fixed electrodes 26, 30 and the movable electrode 28 has a capacitance C1 between one fixed electrode 26 and the movable electrode 28. It has a capacitance C2 between the other fixed electrode 30 and the movable electrode 28. The reference unit 20 including the two fixed electrodes 32 and 34 has a reference electrostatic capacitance CR.

Inside the gate array 103, signals of oscillation frequencies f1, f2, fr which are connected to the differential type sensor unit 18 and the reference unit 20 and are determined by the capacitances D1, C2, CR and resistors not shown. Output C respectively
There are R oscillation circuits 103a, 103b, and 103c, and in response to these signals, in one cycle of the reference oscillation signal from the CR oscillation circuit 103c, the oscillation frequency f1 in the first half cycle and the second half cycle There is a frequency measurement circuit 103d that generates a pulse signal in accordance with the frequency difference of f2 at. The pulse output circuit 104 is the gate array 1
Signal processing such as amplification and level adjustment is performed on the pulse signal output from 03.

A sensor unit B is attached to the pressure receiving unit A.
By gradually pressing in, the sensor is fixed at a position where an appropriate output is obtained. The pressure receiving unit A and the sensor unit B are fixed to each other by press fitting and filling with an adhesive so as to prevent dimensional change with time. The adhesive is filled in a groove formed in the circumferential direction between the base 1 and the sensor unit B when assembled, so that only a necessary portion is fixed.
The base 1 is provided with two small holes (not shown), one for filling the adhesive and one for venting the air.

Next, the operation of the pressure sensor structure constructed as above will be described. The diaphragm chamber 1
When the pressure on the pressure receiving side of 6 is zero, the differential sensor unit 18
Since the movable electrode 28 in is not displaced, the capacitance C1
And C2 are equal. Therefore, the oscillation frequencies f1 and f2 are also equal, and the CR oscillation circuit 103c
Since the frequency difference between the oscillation frequency f1 in the first half cycle and the frequency f2 in the second half cycle of the reference oscillation signal from 1 is zero, no pulse signal is output from the gate array 103.

When a pressure fluid (eg, gas) is introduced from the inlet 10 to the pressure receiving side of the diaphragm chamber 16, the diaphragm 3 is displaced upward in FIG. Due to the upward displacement of the diaphragm 3, the movable portion 28c of the movable electrode 28 is pushed through the plunger 23 and displaced upward in FIG. 1, and the electrostatic capacitances C1 and C2 have different values. Therefore, the oscillation frequency f1 in the first half cycle of the reference oscillation signal from the CR oscillation circuit 103c and the second half 1 /
Since a frequency difference of f2 occurs in two cycles, the gate array 103 outputs the number of pulse signals proportional to the frequency difference, that is, the pressure to be detected.

The capacitances C1 and C2 change depending on the surrounding environment, that is, the temperature and the material composition of the pressure fluid whose pressure is measured. Therefore, the CR oscillation circuit 10
Although the oscillation frequencies f1 and f2 in 3a and 103b also change, the capacitance CR of the reference unit 102 also changes at the same time, so that measurement errors due to changes in the surrounding environment can be eliminated without providing a correction circuit or the like. You can

In the above embodiment, the pressure receiving unit A that receives pressure, the sensor unit B that determines the performance, and the signal processing unit C are united so that they are easy to assemble and individually inspected. Therefore, the performance yield is also good. In addition, each unit A, B, C can be assembled in one direction, which is excellent in mass productivity and can be automated. Also,
No special construction method is required, investment can be suppressed, and an inexpensive sensor structure can be provided.

Further, in the pressure receiving unit A, the diaphragm 3 has a flat surface perpendicular to the displacement direction, and the stopper shape (the stopper for positive pressure of the diaphragm retainer 4) can be set accurately, so that the pressure resistance is high. Performance can be improved. Also, since the output performance can be changed by replacing the diaphragm 3, it can be used for many purposes (pressure specifications).

Since the sensor unit B employs the differential sensor structure (differential sensor portion 18), the sensor linearity is hardly affected by temperature and humidity. Further, since the performance can be secured only by the thickness accuracy of the insulating films 27 and 29, no special material is required,
It can be constructed at low cost. Further, since the reference unit 102 is built in and the absolute value of the characteristic can be corrected by circuit processing, complicated processing such as origin correction during use becomes unnecessary.

In the above embodiment, the negative pressure stopper and the positive pressure stopper for preventing the deformation of the diaphragm due to overload are provided, but only one side may be provided.

Further, the reference portion 20 is arranged with a space provided therebetween by the spacer 19 in order to avoid mutual interference with the differential type sensor portion 18. Instead of this space, the reference portion 20 is provided. By the structure in which the ground electrode is provided between the section 20 and the differential sensor section 18,
You may raise the same effect.

In the differential type sensor section 18, the fixed electrodes 26, 30 and the movable electrode 28 have a structure in which only the effective areas face each other as much as possible to reduce the parasitic capacitance. A protrusion made of an insulator may be provided on a part of the fixed electrode 30 to prevent the fixed electrode 30 and the movable electrode 28 from coming into contact with each other and electrically short-circuiting when an overload is applied. Instead of the protrusions, the surface of the fixed electrode 30 or the movable electrode 28 may be coated with a film made of an insulator.

Further, by covering the entire housing with an external shield plate made of a metal body, it is possible to eliminate the fluctuation of the output due to the influence of the external electric field.

Further, as shown in FIG. 7, the fixed electrodes 26 and 30 of the differential type sensor section 18 are arranged vertically, and the movable electrode 28 is provided between these fixed electrodes 26 and 30 so as to be vertically movable.
It is also possible to move the movable electrode 28 by pushing up the plunger 23 to make the differential type sensor section 18 variable in area. In this case, the sensor linearity can be improved.

Further, the reference portion 20 of the sensor unit B may be composed of an element having a fixed capacitance such as a capacitor. Further, a metal bellows may be used instead of the diaphragm 3, or the metal diaphragm 3 may be fixed to the base 1.

[0050]

As described above, according to the present invention, the pressure receiving unit that detects the pressure of the pressure fluid, the fixed electrode and the movable unit that moves according to the pressure detected by the pressure receiving unit and is insulated and held between the fixed electrodes. A sensor unit having a differential sensor unit composed of electrodes and a reference unit composed of fixed electrodes separated from each other; and a signal processing unit for processing the capacitance of the differential sensor unit and the reference unit and outputting a desired signal. Since it is equipped with a pressure receiving unit that receives pressure, a unit that determines the performance of the sensor unit and a signal processing unit, it is easy to assemble, and since it can be individually inspected, the performance yield is also good. Since the reference unit is built in and the absolute value of the characteristic can be corrected by circuit processing, complicated processing such as origin correction during use can be performed. Is not required. Also. Since the sensor unit employs the differential type sensor structure, the sensor linearity is hardly affected by temperature and humidity.

According to the present invention, in the pressure sensor structure according to claim 1, the pressure receiving unit has a base for accommodating the sensor unit, and the sensor unit has an electrode holder for accommodating the signal processing unit. Since the sensor unit is housed in the base, and the signal processing unit is housed in the electrode holder of this sensor unit, each unit can be assembled in one direction, which is excellent in mass productivity and can be automated. In addition, a special construction method is not required, investment can be suppressed, and an inexpensive sensor structure can be provided.

According to the present invention, in the pressure sensor structure according to claim 1, the pressure receiving unit has a diaphragm detachably accommodated in the base, and the diaphragm has a flat surface perpendicular to the displacement direction. Since the stopper part is provided at the part facing the flat surface of the diaphragm, in the pressure receiving unit, the diaphragm has a flat surface perpendicular to the displacement direction, and the stopper shape can be set accurately, so the pressure resistance performance is improved. it can. Also, since the output performance can be changed by replacing the diaphragm, it can be used for many applications (pressure specifications).

According to the present invention, in the pressure sensor structure according to claim 1, a member for insulating and holding the movable electrode in the differential sensor section of the sensor unit and a member for separating the two fixed electrodes of the reference section from each other are insulated. Since the film is used, the performance of the differential sensor unit and the reference unit can be ensured only by the thickness accuracy of the insulating film, so that no special material is required and the cost can be reduced.

Further, according to the present invention, in the pressure sensor structure according to the first aspect, since the differential type sensor portion of the sensor unit is the area variable type, the sensor linearity is further improved.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a pressure sensor structure according to the present invention.

FIG. 2 is a perspective view of the pressure sensor structure in an exploded state.

FIG. 3 is a plan view of a diaphragm.

FIG. 4 is a partial cross-sectional side view of the diaphragm.

FIG. 5 is a cross-sectional view of the diaphragm with a part thereof omitted.

FIG. 6 is a schematic block diagram of a pressure sensor structure according to the present invention.

FIG. 7 is a perspective view showing another embodiment of the differential sensor unit.

[Explanation of symbols]

 A pressure receiving unit B sensor unit C signal processing unit 18 differential sensor unit 20 reference unit 23 plunger (movable body) 26, 30, 32, 34 fixed electrode 28 movable electrode

Front page continuation (72) Inventor Yoshihiro Umeuchi 10 Ouron Co., Ltd.

Claims (7)

[Claims] 1. A differential sensor unit comprising a pressure receiving unit for detecting the pressure of a pressure fluid, a fixed electrode, and a movable electrode that moves in accordance with the pressure detected by the pressure receiving unit and is insulated and held between the fixed electrodes. A pressure sensor, comprising: a sensor unit having a reference portion composed of fixed electrodes separated from each other; and a signal processing unit for processing the capacitance of the differential sensor portion and the reference portion and outputting a desired signal. Construction. 2. The pressure receiving unit has a base for accommodating the sensor unit, the sensor unit has an electrode retainer for accommodating the signal processing unit, the sensor unit is accommodated at the base of the pressure receiving unit, and the electrode retainer for the sensor unit is accommodated. The pressure sensor structure according to claim 1, wherein the signal processing unit is housed in the pressure sensor unit. 3. The pressure receiving unit has a diaphragm detachably accommodated in a base, the diaphragm has a flat surface perpendicular to the displacement direction, and a stopper portion is provided at a portion facing the flat surface of the diaphragm. The pressure sensor structure according to claim 1, wherein: 4. The pressure sensor according to claim 1, wherein the member for insulating and holding the movable electrode in the differential type sensor portion of the sensor unit and the member for separating the fixed electrode of the reference portion from each other are made of an insulating film. Construction. 5. The pressure sensor structure according to claim 1, wherein the differential type sensor portion of the sensor unit is an area variable type. 6. The pressure sensor structure according to claim 1, wherein the pressure receiving unit has a metal bellows in the pressure receiving portion. 7. The pressure sensor structure according to claim 1, wherein the reference portion of the sensor unit is composed of an element having a fixed capacitance such as a capacitor.