JP2004045424A - Mounting structure of pressure detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent fluctuation of an output characteristic or a temperature characteristic caused by distortion of a diaphragm by stress when a diaphragm type pressure detector is integrated into a conduit. <P>SOLUTION: In this mounting structure of the pressure detector, the pressure detector formed by fixing integrally a diaphragm base equipped with a diaphragm and a sensor base having a built-in sensor element operated by displacement of the diaphragm is inserted through a gasket into an insertion hole of a fixture body fixed on a pipe conduit or a mechanical device, and the pressure detector is pressed and fixed gastightly by a presser member inserted into the insertion hole from the upper side. In the structure, the presser member abuts on the body part upper face of the diaphragm base and the gasket abuts on the body part lower face thereof respectively, and a shallow groove is formed in a ring shape on the inside position of the abutting part with the presser member on the body part upper face and a shallow groove is formed in a ring shape on the inside position of the abutting part with the gasket on the body part lower face, and distortion generated by pressing by the presser member is absorbed by both shallow grooves. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to an improvement in a mounting structure of a pressure detector mainly using a sensor chip (pressure-sensitive element), and is mainly used in a strongly corrosive gas supply system in a semiconductor manufacturing facility. is there.

For detecting the fluid pressure in a pipeline, a diaphragm-type pressure detector using a sensor chip (pressure-sensitive element) or a strain gauge has been widely used.
9 and 10 show an example of the structure of a diaphragm-type pressure detector, which has been disclosed by the present applicant as JP-A-10-82707 (Patent Document 1) and JP-A-11-212593 (Patent Document 2). Is what you are doing. That is, in FIGS. 9 and 10, 1 is a sensor base, 2 is a sensor chip (pressure sensing element), 3 is a diaphragm, 4 is a diaphragm base, 5 is a pressure transmission medium (silicon oil), and 6 is a seal. Ball, 7 is a lead pin, 8 is a weld, 10 is a fluid pressure, and when the fluid pressure 10 is applied to the sensor chip 2 via the diaphragm 3 and the pressure transmitting medium 5, a semiconductor pressure transducer forming the sensor chip 2 A voltage signal proportional to the pressure is output to the outside through the lead pin 7.

11 and 12 show an example of a structure for attaching the diaphragm type pressure detector shown in FIGS. 9 and 10 to a pipe or the like, and FIG. 13 is an enlarged sectional view of a portion A in FIG. FIG.
11 to 13, reference numeral 11 denotes a fixture body, 12 and 13 denote holding members, 14 denotes bearings, 15 and 16 denote fixtures, and 17 denotes a metal gasket, and a pressing force applied to the pressing members 12 and 13. Thus, the airtightness between the diaphragm base 4 and the fixture main body 11 is maintained via the metal gasket 17.

The diaphragm type pressure detector having the structure shown in FIGS. 9 and 10 can reduce the so-called dead space in a state where it is attached to a pipe or the like, and is advantageous only in improving the gas exchangeability. In addition, a desired passive film can be formed relatively easily on the gas contact surface of the diaphragm 3 to a uniform thickness without unevenness, and excellent practical utility can be achieved.
However, the diaphragm type pressure detector still has many problems to be solved, and the biggest problem is the fluctuation of measured values caused by stress distortion of the diaphragm 3 when the diaphragm type pressure detector is attached to a pipeline or the like. Is a point.

That is, in order to increase the pressure detection sensitivity, the thickness of the diaphragm 3 is selected to be as thin as about 0.05 to 0.06 mm. As a result, when the contact surface of the gasket 17 is brought into contact with the lower surface 4f of the main body of the diaphragm base 4 in the form shown in FIG. 11, the stress distortion generated in the diaphragm 3 when tightening with the fixing bolt 15 becomes inevitable. Thus, the stress applied to the sensor element 2 via the silicon oil 5 changes greatly.
For example, according to a test using a pressure detector having a thickness of the diaphragm 3 of 0.05 to 0.06 mm, an inner diameter of about 10 mm, and a detection pressure of several Torr to 7 kgf / cm ² abs, the pressure P applied to the diaphragm 3 there the case of a high pressure of about P _S = 7kgf / cm ² abs, even when assembled with the pressure detector to the pressure detector fixture main body 11, as compared with the case where the pressure detector is under a free state There is no significant difference between the output V _S (mv) and the temperature characteristic STC (% FS / ° C.).

However, when the pressure P applied to the diaphragm 3 is low, for example, the pressure P ₀ = ₀ kgf / cm ² abs, the output V ₀ is 5.2 mv (the output before the assembly, the output after the assembly is 16.66 mv) by the assembly of the pressure detector. 21.86 mv) or more, and the value of the temperature characteristic ZTC (% FS / ° C.) also greatly fluctuates as 0.162 to 0.719. That is, from the point of output, the variation of the measured value is too large, and the temperature characteristic also has a large fluctuation outside the range that can be compensated, and there is a problem in practical use as a pressure detector.

On the other hand, the outer peripheral edge of the diaphragm base 4 is configured as shown in FIG. 10, and as shown in FIG. 13, the outer peripheral surface 4d of the main body of the diaphragm base 4 and the inner peripheral surface 17d of the metal gasket 17 are not formed. When tightened and fixed as a contact state, the output fluctuation amount ΔV ₀ before and after assembling at a pressure P ₀ = ₀ kgf / cm ² abs can be reduced to ± 3.5 mv or less. Similarly, the value of the temperature characteristic ZTC (% FS / ° C.) is also in the range of 0.052 to 0.259, and even if the pressure detector is attached to an actual pipeline or the like, it can be sufficiently performed by a predetermined calibration operation. It can respond to practical use.

In the pressure detector mounting structure of FIGS. 12 and 13, the output fluctuation amount ΔV ₀ before and after assembling is reduced by the lower surface 4 c of the flange 4 a provided on the diaphragm base 4 and the diaphragm base 4. The gasket 17 is disposed between the outer peripheral surface 4d of the thick (about 2 mm) main body 4b, and the inner peripheral surface 17d of the gasket 17 is not in contact with the outer peripheral surface 4d of the main body 4b. Therefore, even if a downward pressing force is applied to the gasket 17 via the sensor base 1 and the diaphragm base 4 by the sensor pressing member 13, all the upward and downward reaction forces of the gasket 17 are applied to the diaphragm base 4. Because the diaphragm 3 received by the flange portion 4a and formed integrally with the main body portion 4b of the diaphragm base 4 hardly receives strain stress at the time of tightening. That.

However, the smaller the output fluctuation ΔV ₀ and the temperature characteristic ZTC (% FS / ° C.) before and after assembling the pressure detector, it is more advantageous. Even in the case of assembling the structure as shown in FIG. The disadvantage is that the quantity ΔV ₀ is too large.
JP-A-10-82707 Japanese Patent Application Laid-Open No. H11-211593

The present invention relates to a case where the diaphragm type pressure detector having the configuration as shown in FIGS. 9 to 13 disclosed in the above-mentioned JP-A-10-82707 and JP-A-11-212593 is actually applied to a pipe line or the like. It is said that the above-mentioned problem, that is, the variation in the stress and strain of the diaphragm caused when the pressure detector is incorporated into the pressure detector mounting body causes large fluctuations in the output and temperature characteristics, thereby lowering the measurement accuracy of the pressure measurement device. In order to solve the problem, by improving the mounting structure of the pressure detector to the pressure detector mounting body, even when the pressure detector is fixed to the mounting body, the output and temperature The pressure detector can be applied to piping, etc., with little difference from the output and temperature characteristics under the free condition, and without increasing the dead space of the fluid passage. That way, it is an primary object of the invention.

According to the first aspect of the present invention, a pressure detector formed by combining and fixing a diaphragm base having a diaphragm and a sensor base having a built-in sensor element operated by displacement of the diaphragm base is attached to a pipeline or a mechanical device. A pressure detector mounting structure in which a gasket is inserted into the insertion hole of the mounting body, and the pressure detector is air-tightly pressed and fixed by a holding member inserted into the insertion hole from above. At the same time, the pressing member 12 is brought into contact with the upper surface 4e of the main body portion opposite to the diaphragm side of the diaphragm base 4, and the gasket 17 is brought into contact with the lower surface 4f of the main body portion which is the diaphragm side of the diaphragm base 4, respectively. A shallow groove 18a is formed in a ring shape at a position inside the contact portion of the upper surface 4e of the main body portion with the pressing member 12, and a groove on the lower surface 4f of the main body portion is formed. A shallow groove 18b is formed in a ring shape at a position inside the contact portion with the socket 17 so as to be opposed to each other in the vertical direction. Further, the depth dimensions of the shallow grooves 18a and 18b are made equal and both shallow grooves 18a and 18b are made equal. The sum of the depths of the grooves 18a and 18b is set to 1/4 to 2/3 of the thickness of the diaphragm base 4, and the shallow grooves 18a and 18b absorb the strain caused by the pressing by the pressing member 12. This is the basic configuration of the invention.

According to the first aspect of the present invention, the shallow grooves 18a and 18b are formed in opposing shapes on the inner surfaces of the upper surface and the lower surface of the main body of the diaphragm 4, and the strain generated when the pressure detector is tightened and fixed by the pressing member 12 is reduced. Since the structure is configured to absorb the light by the shallow grooves 18a and 18b, the stress distortion generated in the diaphragm 3 is further reduced, and the fluctuation amount of the measured value before and after the fastening is significantly reduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view of a pressure detector according to a first embodiment of the present invention, and FIG. 2 is a partially enlarged cross-sectional view illustrating a mounting structure of the pressure detector according to the first embodiment.
In the following description, the same members as those used in FIGS. 9 to 13 are denoted by the same reference numerals.

1 and 2, 1 is a sensor base, 2 is a sensor chip, 3 is a diaphragm, 4 is a diaphragm base, 5 is a pressure transmitting medium, 7 is a lead pin, 8 is a welded portion, 10 is a mounting body, 12 is a holding member, 14 is a bearing, 15 is a fixture, and 17 is a metal gasket.
The sensor base 1 is formed in a thick disk shape from stainless steel, a chip storage portion 1c is formed in the center of the lower surface, and an oil injection hole 1d and a lead pin insertion hole (not shown) are formed. .
In addition, a known diffusion type semiconductor pressure transducer is used for the sensor chip (pressure-sensitive element). That is, the sensor chip 2 has a diaphragm structure that deforms when subjected to pressure, in which four resistors are formed by the same manufacturing method as the IC, and four resistors connected in a bridge shape are formed. When the resistance value changes by pressurization, a voltage signal proportional to the pressure is output to the output terminal of the bridge.

The diaphragm 3 is formed integrally with the diaphragm base 4 and is formed using stainless steel to a thickness of about 50 μm and an inner diameter of about 10 mmφ. The thickness of the diaphragm 3 is appropriately changed according to the detection pressure range of the detector. In the pressure detector of the present embodiment for measuring an absolute pressure value of several torr to 7 kgf / cm ² , φ It is desirable to set the thickness of the diaphragm 3 of about 10 mm to about 50 μm.
In addition, it is also possible to form the diaphragm 3 separately from the diaphragm base 4 and integrate them by welding.
The gas contact surface of the diaphragm 3 is subjected to a so-called passivation film forming process by a known method, and the outer surface of the gas contact surface is made of approximately 100% chromium oxide having a thickness of about 200 °. A passivation film or a fluoridation passivation film having a thickness of about 1000 to 3000 ° or a mixed oxidation passivation film mainly composed of aluminum oxide and chromium oxide having a thickness of about 200 ° is formed.

The silicone oil 5 serving as the pressure transmitting medium transmits the pressure 10 applied to the diaphragm 3 to the sensor chip 2. Here, a silicone oil having a small temperature expansion coefficient and a small compression coefficient and being chemically stable is used.
The sealing ball 6 is for sealing the silicone oil 5 in the oil injection hole 1d, and here, a ball 6 made of bearing steel is used.
Since the configuration of the diaphragm type pressure detector itself is known, a detailed description thereof is omitted here.

In the diaphragm type pressure used in the present invention, as shown in FIG. 1, shallow grooves 18a and 18b for so-called strain relief are formed in a ring shape on the upper surface 4e and the lower surface 4f of the main body 4b of the diaphragm base 4. Have been.
That is, the shallow grooves 18a and 18b are formed in a ring shape at positions inside the contact portions of the pressing member 12 and the metal gasket 17, respectively. The cross-sectional shape of both shallow grooves 18a and 18b is V-shaped (inverted V-shaped) or U-shaped (inverted U-shaped), and the depth thereof is when the thickness of the diaphragm base 4 is 1.5 to 2.5 mm. , About 0.3 to 0.5 mm.

The depths of the shallow grooves 18a and 18b are substantially the same as shown in FIGS. 1 and 2, and are formed to be vertically opposed to each other, but the two shallow grooves 18a and 18b are not necessarily the same. It need not be a depth dimension. Similarly, the shallow grooves 18a and 18b do not necessarily have to be formed on a straight line, and the formation positions of both may be slightly shifted in the left-right direction from the positions shown in FIGS. is there.
When the thickness of the diaphragm base 4 is 1.5 mm and the depth of the groove is 0.3 mm, the ratio of the total depth of the groove to the thickness of the diaphragm base 4 is 0.3 × 2 / 1.5 = 2/5, and 0.5 × 2 / 1.5 = 2/3 if the depth of the groove is 0.5 mm.
Similarly, when the thickness of the diaphragm base 4 is 2.5 mm, the above values are 0.3 ×
2 / 2.5 ≒ 1/4 and 0.5 × 2 / 2.5 = 2/5.
That is, if the total depth of the grooves is a depth occupying about 1/4 to 2/3 of the thickness of the diaphragm base 4, the stress applied to the diaphragm is sufficiently absorbed as described later, In addition, the diaphragm base 4 can maintain necessary mechanical strength.

In FIG. 2, when the fixing device 15 is tightened, an upward / downward compressive force (upward / downward reaction) is applied to the outer portion of the main body 4 b of the diaphragm base 4 via the holding member 12 and the metal gasket 17. Force). In the event that the fixing device 15 is tightened, the upward / downward compressive force applied to the main body portion 4b of the diaphragm base 4 causes a strain force (for example, an upward / downward compressive force) on the diaphragm 3. Even when a component force is generated and applied to the diaphragm 3), this portion P is formed by the shallow grooves 18a and 18b provided in the main body upper surface 4e and the main body lower surface 4f of the diaphragm base 4 so as to face each other. Is thin, the displacement due to the strain force is absorbed in the vicinity of the thin portion P. As a result, the distortion force is not directly transmitted to the diaphragm 3, and as a result, distortion of the diaphragm 3 is prevented.

3 and 4 are a schematic cross-sectional view of a pressure detector according to an embodiment of the present invention related to the present invention, and a partially enlarged cross-sectional view showing a mounting structure thereof.
In this embodiment, a flange portion 1a and a flange portion 4a are formed above the sensor base 1 and the diaphragm base 4, respectively, and the outer peripheral portions are formed in a state where the both flange portions 1a and 4a face each other. Welded 8.
The diaphragm base 4 is formed of a ring-shaped main body 4b and a flange 4a, and the lower surface 4c of the flange 4a contacts the upper contact surface 17a of the gasket 17 as shown in FIG. It has a sealing surface. Therefore, the lower surface 4c of the flange 4a is finished to a highly accurate smooth surface.

Further, in the present embodiment, the diameter of the diaphragm base 4 is 13 mmφ, the diameter of the diaphragm pressure receiving surface is 11 mmφ, the thickness of the diaphragm 3 is 0.06 mm, the passive film is a chromium oxide film having a thickness of about 200 mm, and the total thickness is 4 mm and 7 lead pins (one of them is a ground electrode) are selected, and 1.5 mA DC is applied to an input circuit (not shown), and the pressure applied to the sensor element (sensor chip) changes. The four resistance values formed from the sensor chip change, and the output voltage V between the output terminals changes.

In the pressure detector used in the present embodiment, as shown in FIG. 3, shallow grooves 18c are respectively provided at a position closer to the inside of the upper surface 1b of the flange portion of the sensor base 1 and a position closer to the inside of the lower surface 4c of the flange portion of the diaphragm base 4. , 18d are formed, the cross-sectional shape of the former shallow groove 18c is formed in a dish shape, and the latter shallow groove 18d is formed in an inverted U-shaped (or inverted V-shaped).

In this embodiment, as shown in FIG. 4, a metal gasket 17 and a pressure detector are inserted into an insertion hole 11 a of a stainless-steel mounting body 11, and the fixing tool 16 interposes a pressing member 13. By pressing the flange upper surface 1 b of the sensor base 1, the pressure detector is airtightly attached via the metal gasket 17.

A cylindrical detector insertion hole 11a is formed in the upper center of the mounting body 11, and the bottom of the insertion hole 11a extends over two steps of a first step 19 and a second step 20. The peripheral wall surface 19 a of the first step portion 19 serves as a guide surface for the pressing member 13. Further, the peripheral wall surface 20a of the second step portion 20 is in contact with the outer peripheral surface 17c of the gasket 17, the horizontal plane 19b is in contact with the lower contact surface 17b of the gasket 17, and the peripheral wall surface 20a and the horizontal plane 20b are in engagement with each other. Is formed.
The inside of the horizontal surface 20b of the second step portion 20 is formed in a tapered portion 21, and a fluid passage 22 is formed in the center of the bottom surface of the insertion hole 11a.

The gasket 17 has a ring shape, and the cross-sectional shape of the sheet portion is formed in a horizontally long rectangle with four chamfered rectangular corners.
The inner peripheral surface 17d of the gasket 17 is not in contact with the outer peripheral surface 4d of the main body 4b of the diaphragm base 4. The upper contact surface 17a of the gasket 17 contacts the lower surface 4c of the flange 4a of the diaphragm base 4. Further, the outer peripheral surface 17c of the gasket 17 is in contact with the peripheral wall surface 20a of the second step portion 20. That is, the fitting portion of the gasket 17 is formed by the flange lower surface 4c of the diaphragm base 4, the peripheral wall surface 20a of the second step portion 20, and the horizontal surface 20b, and the second step portion 20 of the detector insertion hole 11a is formed. The distance between the peripheral wall surface 20a and the outer peripheral surface 4d of the flange main body is set to be substantially the same as or slightly larger than the lateral width of the gasket 17.

In FIG. 4, the gasket 17 has an outer diameter of 14.7 mm, an inner diameter of 13.0 mm, a width of the sheet portion of 1.5 mm, a thickness (height) of the sheet portion of 0.9 mm, and a contact surface 17a of the sheet portion. -Each of the gaskets 17 is formed of SUS316L-P (w melt) as the material of the gasket 17.

The action of the shallow grooves 18c and 18d is the same as that of the first embodiment shown in FIG. 2, and the strain force generated by the upward / downward compressive force (reaction force) applied via the pressing member 13 is reduced. Absorption by the shallow grooves 18c and 18d and the thin portion P between them prevents direct application of strain to the diaphragm 3.

5 and 6 are a schematic cross-sectional view and a partially enlarged cross-sectional view showing a mounting structure of a pressure detector according to another embodiment of the present invention related to the present invention.
In this embodiment, the diaphragm 3 and the diaphragm base 4 are separately formed, and the two are integrated by providing a welded portion 23.
Further, in the present embodiment, a state in which the sealing surface 4g protrudes to a position below the diaphragm 3 on the lower surface side of the diaphragm base 4 (that is, a state in which the sealing surface 4g protrudes below the lower surface 4f of the main body portion of the diaphragm base 4). ), And shallow grooves 18g and 18h having a U-shaped (or V-shaped) cross section are formed facing each other at a height level substantially horizontal to the diaphragm mounting level above the projecting sealing surface 4g. I have.
Further, shallow grooves 18e and 18f each having a U-shaped (or V-shaped) cross section are formed near the inner side of the upper surface 1b of the flange portion of the sensor base 1 and at an intermediate position between the lower surface 4f of the main body portion of the diaphragm base 4.

In the present embodiment, the shallow grooves 18e and 18f also absorb the strain generated by the upward / downward pressing force applied to the diaphragm base 4 via the pressing member 13, and when the fixing tool 16 is tightened. The effect of the strain force directly applied to the diaphragm 3 is further reduced.

7 and 8 are a schematic cross-sectional view and a partially enlarged cross-sectional view illustrating a main part of a pressure detector according to still another embodiment of the present invention related to the present invention.
The structure of the pressure detector according to this embodiment and the mounting structure thereof are basically the same as those of the embodiment shown in FIGS. 5 and 6, but the outer periphery of the flange 1a of the disc-shaped sensor base 1. The part 24 and the outer peripheral part 25 of the diaphragm base 4 (the part outside the dotted line in FIGS. 7 and 8) are formed as hardened parts having high hardness.

Since the outer portions of the sensor base 1 and the diaphragm base 4 are made of a material of high hardness, the radial strain force itself caused by the compressive force applied upward and downward when tightened by the pressing member 13 becomes smaller, Since the strain force is absorbed by the grooves 18e to 18f, the distortion itself of the diaphragm 3 is further suppressed.
The configuration in which the cured portions 24 and 25 are formed can be applied to the pressure detector shown in FIGS. 3 and 4 as a matter of course.

According to the test using the pressure detector and the mounting structure according to the embodiment of FIGS. 3 and 4, the output fluctuation amount ΔV ₀ before and after the assembly at the pressure P ₀ = ₀ kgf / cm ² · abs is about It becomes ± 1.0 mv or less, and the output fluctuation amount ΔV ₀ can be reduced by about 60 to 70% as compared with the conventional case.
Similarly, in the case of the embodiments of FIGS. 5 and 6, the output fluctuation amount ΔV ₀ can be reduced to about ± 1.0 mv or less.
In addition, it has been found that the output fluctuation amount ΔV ₀ can be further reduced in the case of the embodiment of FIGS. 7 and 8 than in the case of the third embodiment.

FIG. 2 is a schematic sectional view of the pressure detector according to the first embodiment of the present invention. It is a partial expanded sectional view showing the mounting structure of the pressure detector concerning a 1st embodiment. 1 is a schematic cross-sectional view of a pressure detector according to an embodiment of the present invention related to the present invention. FIG. 4 is a partially enlarged cross-sectional view illustrating a mounting structure of a pressure detector according to the embodiment of FIG. 3. FIG. 9 is a schematic cross-sectional view of a pressure detector according to another embodiment of the present invention related to the present invention. FIG. 6 is a partially enlarged sectional view showing a mounting structure of the pressure detector according to the embodiment of FIG. 5. FIG. 11 is a schematic cross-sectional view of a pressure detector according to still another embodiment of the present invention related to the present invention. FIG. 8 is a partially enlarged cross-sectional view illustrating a mounting structure of the pressure detector according to the embodiment of FIG. 7. It is a longitudinal section showing an example of the structure of the conventional pressure detector. It is a longitudinal cross-sectional view which shows the other example of the structure of the conventional pressure detector. FIG. 10 is a longitudinal sectional view showing a mounting structure of the conventional pressure detector according to FIG. 9. It is a longitudinal cross-sectional view which shows the mounting structure of the conventional pressure detector shown in FIG. It is an expanded sectional view of the A section of FIG.

Explanation of reference numerals

1 is a sensor base, 1a is a flange portion, 1b is a flange upper surface, 1c is a chip storage portion, 1d is an oil injection hole, 2 is a sensor chip, 3 is a diaphragm, 4 is a diaphragm base, 4a is a flange portion, and 4b is a main body. , 4c is a flange lower surface, 4d is a main body outer peripheral surface, 4e is a main body upper surface, 4f is a main body lower surface, 4g is a sealing surface, 5 is a pressure transmitting medium, 6 is a sealing ball, 7 is a lead pin, 8 is a welded part, 10 is a fluid pressure, 11 is a fixture body, 11a is an insertion hole, 12 and 13 are holding members, 14 is a bearing, 15 is a fixture, 17 is a metal gasket, 17a is an upper contact surface, 17b Is a lower contact surface, 17c is a gasket outer peripheral surface, 17d is a gasket inner peripheral surface, 18a and 18b are shallow grooves, 18c and 18d are shallow grooves, 18e and 18f are shallow grooves, 18g and 18h are shallow grooves, and 19 is a first groove. Step, 20 is the second step , 21 taper portion, 22 the fluid passage, 23 weld 24 cured portion (sensor-based), 25 cured portion (diaphragm base).

Claims (1)

A pressure detector formed by combining and fixing a diaphragm base having a diaphragm and a sensor base having a built-in sensor element actuated by the displacement of the diaphragm base, and an insertion hole of a fixture main body attached to a pipeline or a mechanical device. In the pressure detector mounting structure, the pressure detector is airtightly pressed and fixed by a pressing member inserted into the insertion hole from above with a gasket interposed therebetween. A holding member (12) is provided on the upper surface (4e) of the main body portion opposite to the diaphragm side of (4), and a gasket (17) is provided on a lower surface (4f) of the main body portion on the diaphragm side of the diaphragm base (4). Each of them is brought into contact with each other, and a shallow groove (18a) is formed in a ring shape at a position inside the contact portion of the main body upper surface (4e) with the pressing member (12). A shallow groove (18b) is formed in a ring shape at a position inside the contact portion with the gasket (17) on the lower surface (4f) of the body part so as to be opposed to each other in the vertical direction, and the shallow grooves (18a), ( The depth of the groove of 18b) is made equal, and the total depth of the grooves of both shallow grooves (18a) and (18b) is 1/4 to 2/3 of the thickness of the diaphragm base (4); A structure for mounting a pressure detector, wherein a strain generated by pressing by a holding member (12) is absorbed by both shallow grooves (18a) and (18b).

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