JPH10153509A - Pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a pressure sensor, in which the stress to a diaphragm due to tightening force is relaxed, and in which offset drift is reduced. SOLUTION: A ring-shaped groove 42 is formed on the bottom part 8 of a recessed part 6 on the outer-diameter side of a diaphragm 10, and a wall thickness is made thin in an axial direction. A groove bottom face 430 is formed to be flat in the radial direction, and the wall thickness in the axial direction of a groove bottom part 43 is constant in the radial direction. The groove may be formed in such a way that the wall thickness in the axial direction of the groove bottom part becomes gradually thick toward the outside-diameter side from the inside-diameter side. In addition, a rib which is extended to the radial direction may be formed on the groove bottom part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a pressure sensor.

[0002]

2. Description of the Related Art A conventional pressure sensor 100 is shown in FIG.

[0003] A metal case 1 as a support member, and a screw portion 4 to be screwed into the mounting portion 3 of the counterpart member 2.
And a tightening portion 5 for tightening when screwing the screw portion 4. A recess 6 is formed in the fastening portion 5 as a sensor main body storage portion.

A pressure introducing hole 7 as a through hole is formed along the axis of the case 1. One end of the pressure introducing hole 7 opens at the center of the tip of the screw portion 4, and the other end opens at the center of the bottom 8 of the recess 6.

A step 9 is provided around the opening of the pressure introducing hole 7 at the center of the bottom 8 of the recess 6, and a flange 11 at the opening edge of a metal diaphragm 10 having a substantially U-shaped cross section is provided.
Are fitted into the step 9. The diaphragm 10 has a flange 11
The part is fixed to the case 1 by welding the entire circumference.

As shown in FIG. 11A, an upper portion 12 of the diaphragm 10 is formed to be thin, and a lower surface of the upper portion 12 forms a pressure-sensitive surface 13 facing the pressure introducing hole 7.
A strain gauge 15 is provided on the upper surface 14 of the device via an insulating layer.

As shown in FIG. 11A, a strain gauge 15 provided on the upper surface 14 of the diaphragm 10 has a first gauge 151 and a second gauge 152 on the inner diameter side and a third gauge 153 on the outer diameter side. And a fourth gauge 154, and the four gauges 151, 152, 153, and 154 are shown in FIG.
A bridge circuit 16 as shown in FIG.

The pressure-sensitive surface 13 receives the pressure of the fluid introduced into the pressure introducing hole 7, and the deformation of the pressure-sensitive surface 13 due to the pressure is taken out as a change in the output of the strain gauge 15.

On the outer diameter side of the upper surface 14 of the diaphragm 10, a substantially annular circuit board 17 is provided so as to be substantially flush with the upper surface 14. The outer periphery of the circuit board 17 is fixed to a step 18 provided on the inner periphery of the recess 6. Electronic components (not shown) such as an amplifier for amplifying the output of the strain gauge 15 are mounted on the lower surface of the circuit board 17, and wiring is provided on the upper surface of the circuit board 17.

[0010] Between the circuit board 17 and the bottom surface of the concave portion 6,
The potting agent 19 is filled to protect the electronic components.

A metal plate 20 in the form of a lid is provided above the circuit board 17. The outer periphery of the plate 20 is disposed on the step 21 on the inner periphery of the case 1.

A through capacitor 22 is provided on the plate 20, and an output from the circuit board 17 is taken out via the through capacitor 22.

A lid-like connector portion 23 is mounted on the upper portion of the plate 20. The connector portion 23 is provided on the caulking portion 24 provided on the inner diameter side of the end face of the case 1 with the connector portion 23.
By fitting the outer peripheral flange 25 and caulking,
Fixed.

An O-ring 26 is mounted between the outer edge of the plate 20 and the flange 25 on the outer periphery of the connector 23.

The connector portion 23 is made of resin, and has a substantially rectangular parallelepiped connector 27 at the top. A pin 28 for taking out an output from the circuit board 17 is connected to a connector pin 29 of the connector 27 via a feedthrough capacitor 22. Then, the pressure sensor 100
The output is taken out.

Although there is a disadvantage in terms of cost, once the connector pins 29 and 28 are connected by a flexible circuit, workability in connecting the connector 27 and the circuit board 17 is improved. (Soldering work) and assemblability can also be improved.

The mounting of this type of pressure sensor 100 by screws is usually performed by a tightening portion 5 with a controlled tightening torque.
Can be attached by tightening. When the tightening torque is tightened below the standard value, the material of the case 1 of the pressure sensor 100 expands with respect to the load pressure, and a gap is generated between the material and the mating member mounting portion 3. O-ring 3 in this gap
0 is bitten, and the O-ring 30 is broken by repeated pulsating pressure loads, and leakage occurs. For this reason,
In particular, the high-pressure measurement pressure sensor is tightened with a high tightening torque so as not to cause leakage due to such a seal failure at the time of high-pressure measurement.

[0018]

However, since the case 1 is tightened with a high tightening torque, a large tightening stress is generated in the case 1 and the pressure sensor 1
There is a problem that each of the components 00 is affected.

For example, 500 kg · f / cm ² (49M
The axial force F generated when the pressure sensor for Pa) (screw M18 × 1.5) is mounted with the specified torque (T = 10 kg · fm) is from T = 0.2 Fd (d: nominal screw diameter). F = T / 0.2d = 10 × 10 ² /0.2×1.8=2780 kg · f Therefore, the stress S from the mounting portion 3 is: S = F / A = 2780 / 144.5 = 19.2 kg F / mm ² , and very large stress is applied to the case seating surface 31. As a result, the stress deforms the pressure sensor case 1 and further deforms the diaphragm 10 to affect the strain gauge 15 disposed on the diaphragm 10, thereby causing offset drift.

The present invention has been made to solve the above-mentioned problems of the prior art, and its object is to
An object of the present invention is to alleviate the stress on the diaphragm due to the tightening force and reduce the offset drift.

[0021]

In order to achieve the above object, according to the present invention, a hollow sensor main body storage portion and a bottom portion of the sensor main body storage portion are pressed against the mounting portion of a counterpart member by opposing pressure contact. A fixing means for fixing the sensor body, a through-hole opening at the bottom of the sensor main body storage portion, and mounted on the bottom of the sensor main body storage portion facing the through hole, a pressure-sensitive surface is provided on the opening side, A diaphragm provided with a strain gauge on the opposite side of the pressure-sensitive surface, wherein the pressure of the fluid introduced into the through-hole is sensed by the pressure-sensitive surface, and deformation of the pressure-sensitive surface due to the pressure is detected by the strain gauge. In the pressure sensor for detecting a change in output, a thin portion having a small axial thickness is provided on the bottom of the sensor main body storage portion on the outer diameter side of the diaphragm.

According to this configuration, when the pressure sensor is fixed to the mounting portion of the counterpart member, the bottom of the sensor main body storage portion on the pressure receiving side of the seat receives a load from the mounting portion of the counterpart member. At the bottom of the part, on the outer diameter side from the diaphragm, a thin part with a thin wall in the axial direction is provided, so even if the tightening part is tightened with high torque, the deformation of the thin part with reduced rigidity will cause the mounting of the counterpart Since the stress due to the load from the part is absorbed, the effect of the stress at the time of tightening does not propagate to the diaphragm. Therefore, the deformation of the diaphragm at the time of no load can be suppressed, and the offset drift of the pressure sensor can be reduced.

Further, the thin portion is an annular groove surrounding the diaphragm.

According to this, the thin portion can be easily formed by cutting or forging. Therefore, the offset drift of the pressure sensor can be easily reduced.

Further, a hollow sensor main body storage portion, fixing means for fixing the sensor main body storage portion to the mounting portion of the counterpart member by pressing the bottom portion thereof in opposition to each other, and a through-hole opening at the bottom of the sensor main body storage portion. A hole and a diaphragm mounted on the bottom of the sensor main body storage portion facing the through hole, a pressure-sensitive surface is provided on the opening side, and a strain gauge is provided on the opposite side of the pressure-sensitive surface. A pressure sensor that detects the pressure of the fluid introduced into the through-hole by the pressure-sensitive surface, and detects a deformation of the pressure-sensitive surface due to the pressure as a change in output of the strain gauge. A pressure sensor, wherein an annular groove is provided around a mounting portion of the pressure sensor.

According to this, it is possible to prevent the stress at the time of fixing the pressure sensor from being transmitted to the diaphragm by the annular groove.

Also, a screw portion as fixing means for screwing the sensor main body housing portion into the mounting portion of the counterpart member, and a screw portion provided on the head side of the screw portion for tightening when screwing the screw portion. It is also preferable that a supporting member having a fastening portion is provided, and the hollow sensor main body housing portion is provided in the fastening portion of the supporting member.

According to this, it is possible to integrally provide the sensor main body storage portion and the screw portion as the fixing means as the support member.

[0029] It is also preferable that the fixing means includes a flange provided in the sensor main body accommodating portion, and fastening means for fastening the flange to an attachment portion of the counterpart member.

According to this, since the fastening means fastens the flange portion to the mounting portion of the counterpart member, it is possible to reduce the bending stress generated when the sensor is fixed to the sensor main body storage portion.

The thickness of the bottom of the groove in the axial direction is gradually increased from the inner diameter side to the outer diameter side.

According to this structure, since the bottom of the groove is thinner on the inner diameter side, the stress at the time of tightening is absorbed by the deformation on the inner diameter side whose rigidity is reduced, and
The influence of this stress does not propagate to the diaphragm, and the offset drift of the pressure sensor can be reduced. Furthermore, since the bottom of the groove is thicker on the outer diameter side, the rigidity of the case is increased, and deformation of the case due to stress at the time of tightening is suppressed. Therefore, components such as a circuit board housed in the sensor body housing section are not damaged by the deformation of the case.

If the thickness of the bottom of the groove is gradually increased from the inner diameter side to the outer diameter side, the cutting tool can be given an angle when cutting the groove with a lathe, thereby reducing cutting resistance. , The blade has good durability, and the workability is high.

Further, the angle formed between the bottom surface of the groove and the surface of the bottom portion to be pressed against the mounting portion of the counterpart member is 10 ° to 50 °.

Here, the surface to be pressed against corresponds to the bearing surface of the screw portion or the flange portion, and the surface to be pressed against directly receives the load from the mounting portion of the counterpart member.

By providing the bottom of the groove with an inclination, the axial thickness of the bottom of the groove can be gradually increased from the inner diameter side to the outer diameter side. In this case, if the angle formed between the bottom surface of the groove and the surface of the tightening portion to be pressed against is reduced, the rigidity of the case is reduced, so that the deformation of the diaphragm at no load is suppressed, and the offset drift is reduced. The deformation of the case may damage components such as a circuit board provided in the sensor body storage section in the case. Also, increasing the angle between the bottom surface of the groove and the surface to be pressed against increases the rigidity of the case on the outer diameter side,
Although there is no risk of damaging components such as a circuit board provided in the sensor main body storage section, offset drift is increased. Therefore, it is desirable to select the angle between the bottom surface of the groove and the surface to be pressed against in the range of 10 ° to 50 °.

Further, the present invention is characterized in that the groove has a concave cross section.

In this manner, local stress concentration due to the cross-sectional shape of the groove can be reduced, and the groove can be easily formed by forging.

The groove is provided with a rib extending in a radial direction.

In this case, the rigidity of the case is increased, and the deformation of the case due to the stress at the time of tightening is suppressed. Therefore, components such as a circuit board housed in the sensor body housing section are not damaged by the deformation of the case.

It is desirable that ribs extending from the vicinity of the bottom surface on the inner diameter side of the groove to the side surface on the outer diameter side be equally arranged in the circumferential direction.
The shape and arrangement of the ribs are not limited to those described above.

[0042]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the illustrated embodiment.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
It is sectional drawing which shows schematic structure around the case 41 of the pressure sensor PS1 which concerns on 1st Embodiment.

Regarding the structure of the plate and the connector,
The description will be omitted because it is the same as the conventional example, and the surroundings of the case 41 and the diaphragm 10 will be described.

The same reference numerals are used for the same configuration as the conventional example.

Similarly to the conventional example, the pressure sensor PS1 according to the present embodiment also has a structure in which the tightening portion 5 of the case 41 as a support member and the screw portion 4 as fixing means are integrally formed. , The screw portion 4 is screwed into the mounting portion 3 of the counterpart member 2.

In this embodiment, an annular groove 42 is provided in the bottom 8 of the concave portion 6 on the outer diameter side of the diaphragm 10. The groove bottom 43 has a constant thickness in the radial direction,
0 is formed flat in the radial direction.

As described above, by providing the groove 42 in the bottom 8 of the recess 6, the bottom 8 of the recess 6 becomes thin and the rigidity is reduced. Therefore, when the stress at the time of tightening is applied to the case seating surface 31, the thin groove bottom portion 43 bends,
This stress can be absorbed and the stress on the diaphragm 10 can be reduced. That is, it is possible to reduce the occurrence of offset drift due to the deflection of the diaphragm 10 due to the stress at the time of tightening.

Note that such a groove 42 can be easily manufactured by cutting or forging.

(Second Embodiment) FIG. 2 shows a second embodiment of the present invention.
It is sectional drawing which shows schematic structure around the case 51 of the pressure sensor PS2 which concerns on 2nd Embodiment.

Portions having the same configuration as the conventional example and the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In this embodiment, an annular groove 52 is formed in the bottom 8 of the recess 6 so that the groove bottom 53 becomes gradually thicker from the inner diameter side to the outer diameter side.

As described in the first embodiment, the occurrence of offset drift can be reduced by providing the radially flat groove 42 at the bottom 8 of the recess 6. However, depending on the thickness of the groove bottom 43, the rigidity is insufficient, and deformation of the case 41 due to stress applied to the case 41 from the mounting portion 3 due to the tightening torque, twisting of the case 41 due to the tightening torque, and the like occur. There is a possibility that troubles such as breaking of 17 may occur.

In the pressure sensor PS2 according to the present embodiment,
When the stress at the time of tightening is applied to the case seating surface 31,
In particular, only the thin inner diameter portion 531 of the groove bottom 53 bends to absorb the stress, so that the influence of the stress on the diaphragm 10 can be reduced as in the pressure sensor according to the first embodiment. In addition, in the pressure sensor according to the present embodiment, since the groove bottom portion 53 is formed gradually thicker from the inner diameter side to the outer diameter side, the rigidity of the case 51 is increased by the thick outer diameter portion 532. The shape of the circuit board 17 is maintained, and the circuit board 17 does not crack.
That is, in the pressure sensor PS2 according to the present embodiment, it is possible to reduce the offset drift by reducing the stress applied to the diaphragm 10 and increase the rigidity of the case 51.

FIG. 3 shows the relationship between the angle α formed by the bottom surface 530 of the groove bottom 53 and the seat surface 31 orthogonal to the axis, the stress applied to the diaphragm 10 and the elongation of the circuit board 17.
The results of the analysis are shown.

As can be seen from FIG. 3, the stress (■) applied to the vicinity of the strain gauge portions (153, 154) outside the upper surface 14 of the diaphragm and the stress applied to the vicinity of the strain gauge portions (151, 152) inside the upper surface 14 of the diaphragm. (□)
In both cases, when the angle α of the groove bottom 53 becomes 50 ° or less, the stress is less than that without the groove, and thus the offset drift is reduced. Further, as the angle α of the groove bottom 53 increases, the elongation (△) of the circuit board 17 decreases,
The rigidity of the case 51 is high. Actually, if the angle α of the groove bottom 53 is 10 ° or more, the deformation of the circuit board 17 can be dealt with, and the circuit board 17 is not damaged in this region.

Such a groove 52 can be formed by cutting and forging as in the first embodiment.
If an angle is set to 3, the cutting tool can be given an angle during cutting with a lathe, reducing cutting resistance,
The blade has good durability and high workability.

Therefore, the angle α of the groove bottom 53 is 10 ° to 5 °.
It can be set as appropriate from the 0 ° region.
Taking into account the balance of rigidity, workability, influence on the diaphragm, etc., it is desirable that the angle is about 20 ° to 30 °. However, the angle α of the groove bottom 53 is not limited to this.

FIG. 4 shows that the angle α of the groove bottom 53 of the pressure sensor PS2 in this embodiment is 0 °, 15 °, 30 °,
Tightening torque of 45 ° was changed (horizontal axis (kgf
m)) is a graph of an experimental result in which a relationship between output fluctuation (vertical axis (% FS)) with respect to m)) is obtained. Note that the round plot is data of the pressure sensor 100 according to the related art without a groove.

According to the experimental results, in the pressure sensor (PS2) having the groove formed, the output fluctuation was up to about -0.2 (% FS) with respect to the tightening torque up to 10 (kgfm). On the other hand, the conventional pressure sensor 1
In the case of 00, it was confirmed that the output fluctuated to about -0.35 (% FS), and the effect of the groove formation was confirmed.

FIG. 5 shows the case where the angle α of the groove bottom 53 is set to 30 ° and the axial thickness (thickness of the thinnest portion) of the inner diameter portion 531 is 50 (%) +/− 7 of the case without the groove.
(%) The output fluctuation (vertical axis (%) with respect to the tightening torque (horizontal axis (kgf · m)) of the sample set to a thickness of (%)
It is a graph figure of the experimental result which calculated | required the relationship of (FS)).

The results of the output fluctuations of both samples are almost the same, and are sufficient as long as the axial thickness of the inner diameter portion 531 is about 50 (%) +/− 7 (%) of that without the groove. The effect was obtained, and the effect of groove formation was confirmed.

(Third Embodiment) FIG. 6A is a top view of a case in which a diaphragm of a pressure sensor PS3 according to a third embodiment is mounted (however, a circuit board is omitted). FIG. 6B is a cross-sectional view taken along line AA of FIG. 6A (however, a circuit board is omitted).

Portions having the same configuration as in the conventional example and the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

In the case 61 of the pressure sensor PS3 according to the present embodiment, an annular groove 62 is provided in the bottom 8 of the recess 6 and extends radially in the flat groove bottom 63 of the groove 62, and gradually extends in the outer radial direction. Thick ribs 64 having a triangular cross section are equally arranged in the circumferential direction.

By providing such a groove 62, when a stress at the time of tightening is applied to the case seat surface 31, the influence of the stress on the diaphragm 10 can be reduced, and the offset drift can be reduced. Further, since the ribs 64 are provided at the groove bottoms 63 of the grooves 62, the rigidity of the case 61 is enhanced, so that troubles such as breaking of the circuit board (not shown) 17 do not occur.

The angle β between the upper surface 641 of the rib 64 and the seat surface 31 perpendicular to the axis is equal to the groove bottom 5 in the second embodiment.
3 can be set appropriately from the range of 10 ° to 50 ° as in the case of the angle α, but in consideration of the balance of the rigidity of the case 61, workability, influence on the diaphragm, and the like, 20 ° to 3 °.
It is desirable to set the angle to about 0 °.

In this embodiment, the rib 64 having a triangular cross section is used.
Are arranged equally in the circumferential direction, but the shape, number and arrangement of the ribs are not limited thereto.

(Fourth Embodiment) FIG. 7 shows a fourth embodiment of the present invention.
It is a half sectional view showing the schematic structure of case 71 of pressure sensor PS4 concerning the embodiment.

Portions having the same configuration as the conventional example and the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

In the case 71 of the pressure sensor PS4 according to the present embodiment, a stepped groove 72 in which the groove bottom 723 becomes gradually thicker from the inner diameter side to the outer diameter side is provided in the bottom 8 of the concave portion 6. .

By providing such a stepped groove 72, when a stress at the time of tightening is applied to the case seating surface 31, the inner diameter portion 731 of the groove bottom portion 723 having a thin curved portion and having a concave curved cross section is deformed. To absorb the stress, and the diaphragm 10
And the offset drift can be reduced.

Further, the thick outer diameter portion 732 of the groove bottom portion 723 increases the rigidity of the case 71, so that the circuit board 17 does not crack.

In the present embodiment, the stepped groove 72 is
Although three steps parallel to 1 are formed, the number of steps, the shape of the steps, and the like are not limited to these.

(Fifth Embodiment) FIG. 8 shows a fifth embodiment of the present invention.
It is a half sectional view showing a schematic structure of case 81 of pressure sensor PS5 according to the embodiment.

Portions having the same configuration as the conventional example and the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In the case 81 of the pressure sensor PS5 according to the present embodiment, the cross-sectional shape of the concave portion 6 is configured as a groove 83 that connects the mounting portion 82 joining the diaphragm 10 to the fastening portion 5 with a concave curved cross section.

By providing the groove 83 having such a concave cross section, when a stress at the time of tightening is applied to the case seat surface 31, the concave cross section at the bottom of the groove 83 reduces local stress concentration, In addition, it is possible to improve workability when the groove 83 is formed by forging.

(Sixth Embodiment) FIG. 9 is a view showing pressure sensors PS6, PS7 and PS8 to which the present invention is applied, and is provided with fixing means different from the pressure sensors PS1 to PS5 described above. . However, the configuration of the diaphragm and groove of each pressure sensor in this embodiment is the same as that of the above-described pressure sensors PS1 to PS5. However, the shape and configuration of the case that covers the diaphragm are different depending on the application and purpose. Have been changed.

The pressure sensor PS6 shown in FIG. 9A has a disc-shaped flange portion 92 as a fixing means below the case 91, and a hexagon nut having another through hole having a size through the case 91. The flange portion 92 is pressed by a fixing tool 93 as a fastening means.

In this configuration, the flange portion 92 is
3 and the pressure sensors PS1 to PS5
In this configuration, the rotation torque at the time of the direct tightening is not applied as in the case of the first embodiment, so that it is possible to suppress the generation of the bending stress and the rotation torque applied to the case 91. Therefore, the influence of the stress on the diaphragm 10 can be reduced, and the offset drift can be further reduced.

The pressure sensor PS7 shown in FIG. 9B is provided with a diamond-shaped flange portion 95 as a fixing means at the lower portion of the case 94, and is attached to a mating member by a bolt as a fastening means. Also in this configuration,
The effect of the stress on the diaphragm 10 can be reduced, and the offset drift can be further reduced.

In the pressure sensor PS8 shown in FIG. 9C, a disc-shaped flange 97 is provided at the lower part of the case 96, and the flange 97 is pressed by a diamond-shaped pressing member 98 which is a separate component. Also in this configuration, the influence of the stress on the diaphragm 10 can be reduced, and the offset drift can be further reduced.

[0084]

According to the present invention, when the pressure sensor is fixed to the mounting portion of the counterpart member, the axial thickness provided on the outer diameter side from the diaphragm at the bottom of the sensor main body storage portion becomes thinner. The portion or groove prevents the effect of stress during tightening from being transmitted to the diaphragm. Therefore, the deformation of the diaphragm at the time of no load can be suppressed, and the offset drift of the pressure sensor can be reduced.

According to the support member having the screw portion as the fixing means and the fastening portion provided with the hollow sensor main body storage portion, the sensor main body storage portion and the screw portion as the fixing means are integrally formed as the support member. It is possible to prepare.

Further, the fixing means includes a flange provided in the sensor main body storage portion, and a fastening means for fastening the flange to the mounting portion of the counterpart member. Since the fastening member is fastened to the mounting portion of the counterpart member, the bending stress generated when the sensor member is fixed to the sensor main body storage portion can be reduced.

A thin portion or a groove can be easily formed by cutting or forging.

By changing the thickness of the bottom of the groove, the stress at the time of tightening is not transmitted to the diaphragm, the rigidity of the case is increased, and the deformation of the case due to the stress at the time of tightening is suppressed. Therefore, it is possible to reduce offset drift and prevent damage to components such as a circuit board housed in the sensor body housing due to deformation of the case.

If the thickness of the bottom of the groove is gradually increased from the inner diameter side to the outer diameter side, the cutting tool can be angled when the groove is cut by the lathe, so that the cutting resistance is reduced. , The blade has good durability, and the workability is high.

By setting the angle of the bottom surface of the groove to a predetermined value, it is possible to reduce the offset drift and suppress the deformation of the case at the time of tightening in a well-balanced manner.

By making the cross section of the groove a concave cross section, local stress concentration due to the cross section of the groove can be reduced, and the groove can be easily formed by forging.

By providing the groove with a rib extending in the radial direction, the rigidity of the case is increased, and deformation of the case due to stress at the time of tightening is suppressed. Therefore, components such as a circuit board housed in the sensor body housing section are not damaged by the deformation of the case.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a schematic configuration around a case of a pressure sensor according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a schematic configuration around a case of a pressure sensor according to a second embodiment of the present invention.

FIG. 3 is a graph showing the result of FEM analysis of the relationship between the angle of the groove bottom and the stress applied to the diaphragm and the elongation of the circuit board of the pressure sensor according to the second embodiment of the present invention.

FIG. 4 is a graph showing the relationship between the tightening torque of the pressure sensor and the output fluctuation, wherein the sample has no groove and a plurality of samples in which the angle of the bottom surface of the groove is changed.

FIG. 5 is a graph showing the relationship between the tightening torque of the pressure sensor and output fluctuation. In the sample, the angle of the bottom surface of the groove was set to 30 °, and the thickness of the thinnest portion of the inner diameter portion was changed. Things.

FIG. 6A is a top view illustrating a schematic configuration of a case of a pressure sensor according to a third embodiment of the present invention. FIG. 6B is a sectional view taken along line AA of FIG.

FIG. 7 is a half sectional view showing a schematic configuration of a pressure sensor according to a fourth embodiment of the present invention.

FIG. 8 is a sectional view showing a schematic configuration of a pressure sensor according to a fifth embodiment of the present invention.

FIG. 9 is a sectional view illustrating a schematic configuration of a pressure sensor according to a sixth embodiment of the present invention.

FIG. 10 is a cross-sectional view illustrating a schematic configuration of an entire pressure sensor according to the related art.

FIG. 11A is a cross-sectional view illustrating a schematic configuration of a diaphragm of a pressure sensor according to a conventional technique. FIG.
(B) is a circuit diagram showing a bridge circuit of a strain gauge provided on a diaphragm of a pressure sensor according to the related art.

[Explanation of symbols]

1,41,51,61,71,81,91,94,96
Case 2 Counterpart member 3 Attachment part 4 Screw part 5 Tightening part 6 Concave part 7 Pressure introduction hole 8 Bottom part 10 Diaphragm 11 Flange 12 Upper part 13 Pressure sensing surface 14 Upper surface 15 Strain gauge 16 Bridge circuit 17 Circuit board 18 Step part 19 Potting agent 20 Plate 21 Step portion 22 Through capacitor 23 Connector portion 24 Caulking portion 25 Flange 26 O-ring 27 Connector 28 pin 29 Connector pin 30 O-ring 31 Seat 42, 52, 62, 72, 83 Groove 43, 53, 63, 723 Groove bottom 430, 530 Groove bottom surface 531 Inner diameter portion 532 Outer diameter portion 64 Rib 641 Rib upper surface 731 Inner diameter portion 732 Outer diameter portion 82 Mounting portion PS1, PS2, PS3, PS4, PS5 Pressure sensor PS6, PS7, PS8 Pressure sensor

Claims (9)

[Claims] 1. A hollow sensor main body storage portion, fixing means for fixing the sensor main body storage portion to a mounting portion of a counterpart member by pressing a bottom portion thereof in opposition to each other, and a through-hole opening at the bottom portion of the sensor main body storage portion. A hole, which is mounted on the bottom of the sensor main body storage portion facing the through hole, a pressure-sensitive surface is provided on the opening side, and a strain gauge is provided on the opposite side of the pressure-sensitive surface. A pressure sensor that senses the pressure of the fluid introduced into the through-hole by the pressure-sensitive surface and detects deformation of the pressure-sensitive surface due to the pressure as a change in the output of the strain gauge. A pressure sensor having a thin portion having a small thickness in an axial direction on an outer diameter side of a diaphragm. 2. The pressure sensor according to claim 1, wherein the thin portion is an annular groove surrounding the diaphragm. 3. A hollow sensor main body storage portion, fixing means for fixing the sensor main body storage portion to a mounting portion of a counterpart member by pressing a bottom portion of the sensor main body storage portion, and a through-hole opening at the bottom of the sensor main body storage portion. A hole, which is mounted on the bottom of the sensor main body storage portion facing the through hole, a pressure-sensitive surface is provided on the opening side, and a strain gauge is provided on the opposite side of the pressure-sensitive surface. A pressure sensor that detects a pressure of the fluid introduced into the through-hole by the pressure-sensitive surface and detects a deformation of the pressure-sensitive surface due to the pressure as a change in output of the strain gauge; and a diaphragm at a bottom of the sensor main body housing. A pressure sensor, wherein an annular groove is provided around a mounting portion of the pressure sensor. 4. A screw portion as fixing means for screwing the sensor main body housing portion into a mounting portion of a counterpart member, and a screw portion provided on the head side of the screw portion for tightening when screwing the screw portion. The pressure according to any one of claims 1 to 3, further comprising a support member having a fastening portion, wherein the hollow sensor main body housing portion is provided in the fastening portion of the support member. Sensor. 5. The fixing device according to claim 1, wherein the fixing unit includes a flange provided in the sensor main body storage unit, and a fastening unit for fastening the flange to an attachment portion of the counterpart member. 4. The pressure sensor according to claim 3. 6. The pressure according to claim 2, wherein the thickness of the bottom of the groove in the axial direction gradually increases from the inner diameter side to the outer diameter side. Sensor. 7. An angle formed between a bottom surface of the groove and a surface of the bottom portion to be brought into pressure contact with a mounting portion of a counterpart member on the bottom portion is 10 degrees.
7. The pressure sensor according to claim 6, wherein the angle is from 50 to 50 degrees. 8. The pressure sensor according to claim 2, wherein the groove has a concave cross section. 9. The pressure sensor according to claim 2, wherein a radially extending rib is provided in the groove.