JP2022118829A - pressure sensor - Google Patents

Abstract

To provide a pressure sensor that can reduce bolting shift without increasing the size of a base body.SOLUTION: A pressure sensor comprises: a base body 41 that is superimposed on a fitting seat for a sensor with a seal member therebetween and fastened with bolts for fitting 43; a sensor chip 42 that is bonded to an outer end part 41a of the base body 41; a pressure receiving chamber that is formed such that a barrier diaphragm provided on an inner end part of the base body 41 becomes part of a wall, and is partitioned from fluid to be measured; and a pressure guide path that is formed inside the base body 41 to extend from the pressure receiving chamber to the sensor chip 42. On the outer end part 41a of the base body 41, a bearing surface 44 is formed which receives fastening forces from the bolts for fitting 43, and grooves 61 are formed which constitute the boundary between the bearing surface 44 and a bonding part 56 to which the sensor chip 42 is bonded.SELECTED DRAWING: Figure 3

Description

The present invention relates to a pressure sensor comprising a base body bolted to a sensor mounting seat and a sensor chip adhered to the base body.

Conventionally, when measuring the flow rate of a fluid to be measured, the pressure of the fluid to be measured is sometimes detected by a pressure sensor, as described in Patent Document 1, for example. As a pressure sensor for detecting this pressure, there is one configured as shown in FIG. 6, for example. A pressure sensor 1 shown in FIG. 6 includes a base body 4 fastened to a sensor mounting seat 2 with a plurality of mounting bolts 3 , and a sensor chip 5 adhered to the outer end of the base body 4 .

The sensor mounting seat 2 has a primary side pressure guiding port 2a and a secondary side pressure guiding port 2b through which the pressure of the fluid 6 to be measured is introduced.
The base body 4 includes a primary pressure receiving chamber 8 whose wall is a part of a primary pressure barrier diaphragm 7 facing the primary pressure guiding port 2a, and a secondary pressure barrier diaphragm 9 facing the secondary pressure guiding port 2b. A secondary pressure receiving chamber 10 that forms a part of the wall, a primary pressure guiding path 11 extending from the primary pressure receiving chamber 8 to the sensor chip 5, and a secondary pressure guiding path extending from the secondary pressure receiving chamber 10 to the sensor chip 5. It has roads 12 and so on. The primary pressure receiving chamber 8, the secondary pressure receiving chamber 10, the primary pressure conduit 11, and the secondary pressure conduit 12 are filled with a liquid 13 for pressure transmission.

The base body 4 is fastened to the sensor mounting seat 2 with a plurality of mounting bolts 3 with metal O-rings 14 and 15 sandwiched between the base body 4 and the sensor mounting seat 2 . The metal O-rings 14 and 15 exhibit high sealing performance even under severe conditions such as high temperature and high pressure, and maintain sealing performance even in an ultra-high vacuum. In addition, since attachment and detachment are easier than connecting means such as welding, maintenance and replacement of the pressure sensor 1 can be easily performed.

JP 2019-128168 A

In the conventional pressure sensor 1 shown in FIG. 6, the mounting bolt 3 is tightened so that the metal O-rings 14 and 15 are sandwiched between the sensor mounting seat 2 and the base body 4 and plastically deformed. When the base body 4 is fastened to the sensor mounting seat 2 with the mounting bolts 3 in this manner, a large stress is generated around the metal O-rings 14 and 15, and the base body 4 is deformed. The deformation of the base body 4 also extends to the bonding portion 16 to which the sensor chip 5 is bonded. If the sensor chip 5 is highly sensitive, it will be affected by the distortion of the bonding portion 16, so that the sensor output will shift to the high pressure side or the low pressure side according to the tightening force of the mounting bolt 3. FIG. Hereinafter, such a sensor output shift is simply referred to as "volting shift".

Increasing the thickness of the base body 4 is effective in reducing the bolting shift. However, if the base body 4 is formed thick, the pressure sensor 1 becomes large and may interfere with peripheral devices.
In recent years, there has been a growing need for higher precision and smaller size in differential pressure mass flow controllers for the semiconductor market. there is

SUMMARY OF THE INVENTION An object of the present invention is to provide a pressure sensor capable of reducing the bolting shift without increasing the size of the base body.

In order to achieve this object, the pressure sensor according to the present invention includes a base which is superimposed on a sensor mounting seat having a pressure guide port through which the pressure of a fluid to be measured is transmitted, via a sealing member, and fastened with a mounting bolt. a body; a sensor chip adhered to an outer end of the base body opposite to the sensor mounting seat; a pressure receiving chamber separated from the fluid to be measured by forming a barrier diaphragm that receives the pressure of the fluid as a part of the wall; and a pressure receiving chamber formed inside the base body to extend from the pressure receiving chamber to the sensor chip. and a pressure guide passage filled with a liquid for transmitting pressure, and a bearing surface that receives fastening force from the mounting bolt is formed on the outer end of the base body, and the bearing surface and a groove forming a boundary with the bonding portion to which the sensor chip is bonded.

In the pressure sensor according to the present invention, the mounting bolts are arranged on one side and the other side of the base body at predetermined intervals in a direction perpendicular to the direction in which the two side portions are arranged. a first groove extending along the plurality of mounting bolts provided on the one side of the base body, and a first groove provided on the other side of the base body. and second grooves extending along the plurality of mounting bolts.

In the pressure sensor according to the present invention, the groove may be formed so as to extend from one end face to the other end face of the base body.

According to the invention, the groove in the base body interrupts the transmission path of the force transmitted on the surface of the base body. For this reason, it becomes difficult for force to be transmitted from the mounting bolt side to the bonding portion of the base body to which the sensor chip is bonded, so that the bonding portion is less likely to be distorted and the bolting shift is reduced. In order to suppress the distortion of the bonding portion in this way, it is not necessary to increase the thickness of the base body.
Therefore, it is possible to provide a pressure sensor capable of reducing the bolting shift without increasing the size of the base body.

FIG. 1 is a cross-sectional view of a mass flow controller equipped with pressure sensors according to the present invention. FIG. 2 is a cross-sectional view of the essential parts of the pressure sensor according to the first embodiment. FIG. 3 is a plan view of the base body and sensor chip. FIG. 4 is a perspective view of the base body and sensor chip. FIG. 5 is a plan view of the base body and sensor chip showing a modification of the groove. FIG. 6 is a cross-sectional view of part of a conventional pressure sensor.

An embodiment of a pressure sensor according to the present invention will be described in detail below with reference to FIGS. 1 to 5. FIG. This embodiment shows an example of applying the present invention to a pressure sensor used to measure the flow rate of a fluid to be measured.

A pressure sensor 21 shown in FIG. 1 is attached to a laminar flow element 23 of a differential pressure type mass flow controller 22 . The differential pressure mass flow controller 22 includes a passage forming member 25 that forms a fluid passage 24, a valve 26 that adjusts the flow rate of the fluid, and a laminar flow element 23 that allows the fluid to flow as a laminar flow. A pressure sensor 21 according to the present invention is attached to the laminar flow element 23 to detect the pressure of the fluid on the upstream side and the pressure of the fluid on the downstream side within the laminar flow element.

The pressure sensor 21 is attached to the sensor mounting seat 31 of the laminar flow element 23, as shown in FIG. The sensor mounting seat 31 has a primary pressure guide port 32 communicating with the upstream side of the laminar flow element 23 and a secondary pressure guide port 33 communicating with the downstream side of the laminar flow element 23 . ing. The pressure of the fluid to be measured 34 flowing upstream in the laminar flow element 23 is transmitted to the primary side pressure guide port 32 . The pressure of the fluid to be measured 34 flowing downstream in the laminar flow element 23 is transmitted to the secondary pressure guide port 33 .

Two metal O-rings 35 and 36 and a spacer 37 are provided between the sensor mounting seat 31 and the pressure sensor 21 . The metal O-rings 35 and 36 are made of annular pipes made of a metal material, and are arranged so as to be positioned concentrically with respect to the primary side pressure guide port 32 and the secondary side pressure guide port 33, respectively. ing. In this embodiment, the metal O-rings 35, 36 correspond to the "sealing member" of the present invention. Spacers 37 are provided so as to close gaps formed outside the metal O-rings 35 and 36 .

The pressure sensor 21 is adhered to a base body 41 superimposed on the sensor mounting seat 31 via metal O-rings 35 and 36, and to an outer end portion 41a of the base body 41 opposite to the sensor mounting seat 31. and a sensor chip 42 .
As shown in FIG. 3 , the base body 41 is rectangular in plan view and fastened to the sensor mounting seat 31 with a plurality of mounting bolts 43 . The mounting bolts 43 are attached to one side portion 41b and the other side portion 41c of the base body 41 in the lateral direction in a direction orthogonal to the direction in which these side portions 41b and 41c are arranged (the longitudinal direction of the base body 41 and They are provided at a plurality of positions arranged at predetermined intervals in the left-right direction in FIG.

The surface of the portion of the outer end 41a of the base body 41 corresponding to the mounting bolt 43 is formed flat so as to form a bearing surface 44 with which the head 43a of the mounting bolt 43 contacts.
The mounting bolt 43 is tightened so that the head portion 43 a presses the seat surface 44 toward the sensor mounting seat 31 . The seat surface 44 receives a fastening force from the mounting bolt 43 when the mounting bolt 43 is tightened. In FIG. 3, the broken position of FIG. 2 is indicated by line II-II.

At the inner end 41d of the base body 41 facing the sensor mounting seat 31 and at a position corresponding to the primary side pressure guide port 32, a primary side pressure receiving chamber 46 is formed, the wall of which is part of the barrier diaphragm 45. It is At the inner end portion 41 d of the base body 41 facing the sensor mounting seat 31 and corresponding to the secondary side pressure guide port 33 , a barrier diaphragm 47 is provided as a part of the wall of the secondary side pressure receiving port 41 d . A chamber 48 is formed.

The barrier diaphragms 45 and 47 are made of a metal material and are disc-shaped. there is Therefore, the barrier diaphragms 45 and 47 receive the pressure of the fluid 34 to be measured and partition the inside of the primary side pressure receiving chamber 46 and the inside of the secondary side pressure receiving chamber 48 from the fluid 34 to be measured.

The primary pressure receiving chamber 46 is connected to a primary pressure guiding path 51 formed inside the base body 41 . The secondary pressure receiving chamber 48 is connected to a secondary pressure guiding path 52 formed inside the base body 41 . The primary side pressure guiding path 51 and the secondary side pressure guiding path 52 are formed so as to penetrate the base body 41 from the inner end portion 41d to the outer end portion 41a, respectively, and are filled with a liquid 53 for pressure transmission. It is The liquid 53 is also filled in the primary side pressure receiving chamber 46 and the secondary side pressure receiving chamber 48 .

The primary side pressure guide path 51 communicates the primary side pressure receiving chamber 46 and a primary side pressure detection portion (not shown) of the sensor chip 42 . The secondary-side pressure guide path 52 communicates the secondary-side pressure receiving chamber 48 with a secondary-side pressure detecting portion (not shown) of the sensor chip 42 . Therefore, the pressure of the fluid 34 to be measured in the laminar flow element 23 is transmitted to the primary side pressure receiving chamber 46 and the secondary side pressure receiving chamber 48 via the barrier diaphragms 45 and 47, and the liquid 53 for pressure transmission is transmitted. Through the primary side pressure receiving chamber 46 and the secondary side pressure receiving chamber 48 , the pressure is transmitted to the sensor chip 42 via the primary side pressure guiding path 51 and the secondary side pressure guiding path 52 .

An outer end portion 41a of the base body 41 is provided with a relay substrate 54 and a connector 55 for electrically connecting the sensor chip 42 and an external detection circuit (not shown).
A groove 61 extending in the longitudinal direction of the base body 41 is formed in the outer end portion 41a of the base body 41, as shown in FIG. This groove 61 constitutes a boundary between the seat surface 44 and the bonding portion 56 to which the sensor chip 42 is bonded. The grooves 61 according to this embodiment include first grooves 61a extending along a plurality of mounting bolts 43 provided on one side portion 41b of the base body 41, and grooves 61a provided on the other side portion 41c of the base body 41. and second grooves 61 b extending along the plurality of mounting bolts 43 .

These first and second grooves 61a and 61b extend from one longitudinal end surface 41e of the base body 41 to the other longitudinal end surface 41f, as shown in FIG. In order to form the groove 61, it is necessary to satisfy the following conditions. This condition is that the tangent line L of the head 43a extending from the vertex of the sensor chip 42 crosses the groove 61 in plan view shown in FIG. Therefore, the groove 61 can be formed as shown in FIG.
The groove 61 shown in FIG. 5 extends from the vicinity of the one end surface 41e of the base body 41 to the vicinity of the other end surface 41f, and does not open at the one end surface 41e and the other end surface 41f.

A groove 61 formed between the bonding portion 56 and the mounting bolt 43 blocks the transmission path of force transmitted on the surface of the outer end portion 41 a of the base body 41 . That is, when the mounting bolt 43 is tightened to such an extent that the metal O-rings 35 and 36 are plastically deformed, the center side of the outer end portion 41a of the base body 41 is pulled toward the outer edge side by the head portion 43a of the mounting bolt 43. Become. In the pressure sensor 21 according to this embodiment, since the outer end portion 41 a is provided with the groove 61 , force is less likely to be transmitted to the bonding portion 56 from the mounting bolt 43 side. Moreover, since the groove 61 can be formed away from the bonding portion 56 toward the mounting bolt 43 side, the area (pressure resistance) of the bonding portion 56 can be increased, and stress generation in the bonding portion 56 can be suppressed. becomes possible.
Therefore, the bonding portion 56 is less likely to be distorted, and the bolting shift is reduced. In order to suppress the distortion of the bonding portion 56 in this way, it is not necessary to increase the thickness of the base body 41 .
Therefore, according to this embodiment, it is possible to provide a pressure sensor capable of reducing the bolting shift without increasing the size of the base body 41 .

The mounting bolts 43 according to this embodiment are arranged on one side 41b and the other side 41c of the base body 41 at a plurality of positions arranged at predetermined intervals in a direction perpendicular to the direction in which these both sides are arranged. are provided respectively. The groove 61 includes a first groove 61a extending along a plurality of mounting bolts 43 provided on one side portion 41b of the base body 41 and a plurality of mounting bolts provided on the other side portion 41c of the base body 41. 43 and a second groove 61b extending along the groove 43. As shown in FIG.
Therefore, even though a plurality of mounting bolts 43 are used, the first and second grooves 61a and 61b can reliably prevent the bonding portion 56 from being distorted.

As shown in FIGS. 3 and 4, by forming the groove 61 extending from the one end surface 41e of the base body 41 to the other end surface 41f, the groove 61 can be easily formed by machining. Therefore, it is possible to easily manufacture the base body 41 having the groove 61 in the outer end portion 41a.

21 Pressure sensor 31 Mounting seat for sensor 32 Primary pressure guide port 33 Secondary pressure guide port 34 Fluid to be measured 35, 36 Metal O-ring (sealing member) 41 Base Body 41a Outer end 41b One side 41c Other side 41d Inner end 41e One end surface 41f Other end surface 42 Sensor chip 43 Mounting bolt 44 Seat Surfaces 45, 47 Barrier diaphragm 46 Primary pressure receiving chamber 48 Secondary pressure receiving chamber 51 Primary pressure guiding path 52 Secondary pressure guiding path 53 Liquid 56 Adhesive portion 61... groove, 61a... first groove, 61b... second groove.

Claims (3)

a base body overlaid on a sensor mounting seat having a pressure guide port through which the pressure of the fluid to be measured is transmitted via a sealing member and fastened with a mounting bolt;
a sensor chip adhered to an outer end of the base body opposite to the sensor mounting seat;
A barrier diaphragm, which is provided at an inner end portion of the base body facing the sensor mounting seat and receives the pressure of the fluid to be measured, is formed so as to form a part of the wall and is separated from the fluid to be measured. a pressure receiving chamber;
a pressure guide path formed inside the base body to extend from the pressure receiving chamber to the sensor chip and filled with a liquid for pressure transmission;
The outer end portion of the base body is formed with a seat surface that receives a fastening force from the mounting bolt, and a groove forming a boundary between the seat surface and an adhesive portion to which the sensor chip is adhered. A pressure sensor characterized in that is formed. The pressure sensor of claim 1, wherein
The mounting bolts are provided on one side and the other side of the base body at a plurality of positions arranged at predetermined intervals in a direction perpendicular to the direction in which the two side portions are arranged,
The groove is
a first groove extending along the plurality of mounting bolts provided on the one side of the base body;
and a second groove extending along the plurality of mounting bolts provided on the other side of the base body. The pressure sensor according to claim 1 or claim 2,
A pressure sensor, wherein the groove is formed so as to extend from one end face to the other end face of the base body.

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