JP3366242B2 - Mounting structure of pressure sensor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting structure of a pressure sensor used for an electric-air converter of a valve positioner or the like.

[0002]

2. Description of the Related Art A valve positioner used for automatic control of an automatic control valve is widely used in various plants such as petrochemical and chemical industries (Japanese Patent Laid-Open No. 4-185901).

FIG. 7 shows the basic structure of a valve positioner of this type. This valve positioner has an input signal IO
(For example, 4 mA to 20 mA) is converted into a voltage by the current-voltage conversion unit 2, this voltage is converted into torque by the torque motor 3, and then converted into an air pressure signal by the nozzle flapper mechanism mechanism 4 and taken out and amplified by the pilot relay 5. ,
By transmitting the output air pressure Pout to the actuator of the valve, the operating shaft of the valve is controlled to a position corresponding to the input signal I0. Also, the output air pressure P
The pressure sensor 6 converts out into an electric signal, and the electric signal is fed back to the current-voltage converter 2 to balance the nozzle flapper mechanism 4 with the force generated by the input signal I0.

As the pressure sensor 6, for example, one using a semiconductor pressure sensor is known (example: Syokai 59).
-135654, JP-B-58-47013, etc.). The supply of the output air pressure Pout to the pressure sensor 6 is
Usually done by tube.

FIG. 8 is a sectional view showing a conventional pressure sensor mounting structure. In the figure, reference numeral 10 denotes a printed wiring board which is attached to a bracket 11 together with the pressure sensor 6 with screws 12, and the printed wiring board 10 has screws 13
Is fixed to the air circuit forming member 15 via the stud 14.

The air circuit forming member 15 is composed of a case for accommodating the pressure sensor 6, and the air passage hole 16 is formed in the thickness thereof.
a, 16b are formed, and these air passage holes 16a, 1 are formed.
6b and the air introduction parts 17a and 17b of the pressure sensor 6 are connected by tubes 18a and 18b, respectively. One end of each tube 18a, 18b is fitted into a joint 19 and clamped and fixed by a ring-shaped clamp 20, and the joint 19 is fitted in the air passage holes 16a, 16b and fixed by an adhesive. On the other hand, the other end side is fitted into the air introducing portions 17a and 17b and clamped by a ring-shaped clamp 21. The output air pressure Pout is introduced to one of the air introducing portions 17a,
The other air introducing portion 17b is open to the outside of the air circuit forming member 15.

[0007]

As described above, in the conventional pressure sensor mounting structure, the pressure sensor 6 is attached to the bracket 11.
The printed circuit board 10 together with the printed circuit board 10, and the printed circuit board 10 is screwed to the air circuit forming member 15, and the air introducing portions 17a and 17b of the pressure sensor 6 and the air circuit forming member 1 are attached.
5 of the air passage holes 16a, 16b to the tubes 18a, 18
It was connected by b.

However, in such a mounting structure, since the tubes 18a and 18b are required, there is a problem that not only the number of parts is increased but also a piping space for the tubes 18a and 18a is required. In addition, each end of the tubes 18a and 18b is connected to the air introduction part 17
Since a and 17b are connected to the joint 19 and then clamped with clamps 20 and 21 in order to prevent disconnection and air leakage, the number of parts is further increased, and there is a problem that assembly work and maintenance are troublesome.

The present invention has been made in order to solve the above-mentioned conventional problems. The object of the present invention is to eliminate the need for tubes, clamps, etc., and to save space and reduce the number of parts. Another object of the present invention is to provide a pressure sensor mounting structure that can be manufactured at low cost and can be easily assembled and maintained.

[0010]

To achieve the above object, a first invention is to provide an air circuit forming member having an air passage hole, a pressure sensor having an air introducing portion, and a sealing member having a through hole. The pressure sensor is pressed through the seal member to the air circuit forming member, and the air passage hole is provided with a pressing member that communicates with the air introducing portion through the through hole. The air introducing portion of the pressure sensor is tapered. A taper is formed and press-fitted into the through hole of the seal member by the pressing member.

A second invention is the same as the first invention,
It is characterized in that an annular bead surrounding the air passage hole or the through hole is integrally provided on either one of the joint surfaces of the seal member and the air circuit forming member.

A third invention is characterized in that, in the above-mentioned first or second invention, a recess communicating with the air passage hole is formed on the surface of the air circuit forming member, and the seal member is fitted in the recess. And

According to a fourth aspect of the present invention, in the third aspect of the present invention, the recess of the air circuit forming member is formed into a recess having a taper that expands toward the pressure sensor, and the sealing member is formed into a spherical body. Characterize.

A fifth aspect of the invention is the same as the third aspect of the invention.
The recess of the air circuit forming member is formed in a circular shape with a constant hole diameter,
The seal member is formed in a truncated cone shape.

In the first aspect of the invention, the tube is not required because the air introduction portion of the pressure sensor is connected to the air passage hole of the air circuit forming member via the seal member. Further, when the pressure sensor is pressed against the air circuit forming member by the pressing member, a clamp is not required, and moreover, the air introducing portion is brought into close contact with the inner peripheral surface of the through hole to obtain good sealing performance. As the pressing member of the pressure sensor, a fixing member such as a bracket to which the pressure sensor is attached or a spring can be used. When the fixing member is used as the pressing member, the pressure sensor may be attached to the fixing member at a position where the air introducing portion is pressed against the seal member when the fixing member is fixed to the air circuit forming member. When a spring is used, the pressure sensor is attached to the fixing member, and this fixing member is attached to the air circuit forming member so as to be movable back and forth and urged toward the air circuit forming member by the spring, or fixed to the air circuit forming member. A member may be fixed, a pressure sensor may be movably attached to the fixed member, and a spring may urge the member toward the air circuit forming member.

In the second invention, when the pressure sensor is pressed against the air circuit forming member by the pressing member, the pressing force applied to the bead per unit area is large. At this time,
The bead elastically deforms and comes into close contact with the seal member or the air circuit forming member, thereby providing a good seal between the both members.

In the third invention, since the seal member is housed in the recess, it does not project to the surface of the air circuit forming member.

In the fourth invention, when the pressure sensor is pressed against the air circuit forming member by the pressing member, the sealing member is pressed against the tapered surface of the recess. At this time, the taper surface presses the seal member toward the center to elastically deform it. Therefore, the inner peripheral surface of the through hole is in close contact with the air introduction portion, and good sealing performance can be obtained. Since the seal member is formed into a spherical body, it can be easily and surely installed in the recess.

In the fifth aspect of the invention, since the sealing member is formed in a truncated cone shape, when it is press-fitted into the recess of the air circuit forming member, good sealing performance can be obtained.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below in detail based on the embodiments shown in the drawings. FIG. 1 is a sectional view showing a first embodiment of a pressure sensor mounting structure according to the present invention,
2 is a sectional view of the seal member, and FIG. 3 is a sectional view of the pressure sensor. In this embodiment, an example applied to a pressure sensor used in a valve positioner is shown. Further, the same components as those shown in the section of the prior art are denoted by the same reference numerals, and the description thereof will be appropriately omitted. In these figures, the pressure sensor 6 is attached to the bracket 11 together with the printed wiring board 10 by a plurality of screws 30. The bracket 11 is also attached to the air circuit forming member 15 by a plurality of screws 31 so that the air introducing portions 17a, 17a of the pressure sensor 6 are provided.
7b are pressed against the seal members 32, respectively. This pressing is performed by attaching the pressure sensor 6 to the bracket 11 at a height position where the air introducing portions 17a and 17b are pressed against the seal member 32 when the bracket 11 is fixed to the air circuit forming member 15.

Here, in the present embodiment, the example in which the bracket 11 is used as the pressing member of the pressure sensor 6 has been shown, but the present invention is not limited to this, and the bracket 11 or the pressure sensor 6 is used as the air circuit forming member using a spring. You may urge in 15 directions. When the bracket 11 is biased by a spring, the pressure sensor 6 is attached to the bracket 11, the bracket 11 is vertically movable with respect to the air circuit forming member 15, and the spring is biased toward the air circuit forming member 15. Good. When the pressure sensor 6 is directly biased, the bracket 11 is fixed to the air circuit forming member 15, the pressure sensor 6 is attached to the bracket 11 so as to be movable up and down, and the spring is biased toward the air circuit forming member 15. Good.

Each air introduction portion 17a of the pressure sensor 6,
The taper 17b is formed such that the tip portion thereof is tapered gradually, and is press-fitted into the through hole 33 of the seal member 32.

The sealing member 32 is formed of a material having elasticity such as rubber or synthetic rubber into a cylindrical body, and has the through hole 33 at the center thereof.
Is fitted and inserted into a recess 34 formed so as to communicate with the air passage holes 16a and 16b (16b is not shown) on the inner bottom surface thereof. The through holes 33 have the same hole diameter D over the entire length. The hole diameter D is set to be larger than the diameter D1 of the tips of the air introducing portions 17a and 17b and smaller than the outer diameter D2 of the base (D1 <D <D2). Further, on the lower surface of the seal member 32, an annular bead 3 surrounding the through hole 33 is formed.
5 are integrally projected. The cross-sectional shape of the bead 35 is arbitrary, and this embodiment shows an example in which it is formed in a semicircular shape. Further, the seal member 32 is not limited to a cylindrical shape, and may be formed in a polygonal cylindrical body.

An example of the pressure sensor 6 is shown in FIG. In this embodiment, an example using a semiconductor pressure sensor is shown. The semiconductor pressure sensor 6 accommodates a sensor chip 42 via a carrier 41 in a cylindrical package 40 formed of a metal such as SUS316, and
An encapsulating liquid 43 such as silicone oil is enclosed and sealed with a pressure receiving diaphragm 44.

The package 40 has a back chamber 45 having a pressure-receiving diaphragm 44, one end of which is filled with the filling liquid 43.
And the other end is opened on the back surface of the package 40, and the enclosed liquid injection hole 4 for injecting the enclosed liquid 43 into the back chamber 45.
6 is formed, and its back side opening is sealed by the ball 47. On the surface side of the pressure receiving diaphragm 44,
The measured pressure P1 is introduced from the air introducing portion 17a.

The carrier 41 is made of a material having a linear expansion coefficient similar to that of the sensor chip 42, for example, Kovar, and is joined to the package 40 by welding or the like so that an electric signal from the sensor chip 42 can be externally supplied. A lead pin 49 that leads to is hermetically sealed by glass 50.

In the sensor chip 42, a gauge acting as a piezoresistive region is formed on the surface of a semiconductor substrate made of Si or the like by an impurity diffusion or ion implantation technique, and leads are formed by vapor deposition of Al to form one of the back surface. By removing the portion by etching, the thickness of 20 to
Strain element of about 100 μm, that is, diaphragm 42A
And is electrostatically bonded (anodic bonded) to the upper surface of the pedestal 48.

As for the pedestal 48, if the thermal strain at the time of joining the sensor chip 42 is transmitted to the sensor chip 42, the temperature characteristic of the pressure sensor 6 is deteriorated and a zero point shift is caused. It is formed of a material having an approximate linear expansion coefficient, such as Pyrex glass or ceramics. On the back surface side of the sensor chip 42, an inner chamber 52 partitioned from the back chamber 45 by the formation of the diaphragm 42A is formed.
The inner chamber 52 is open to the atmosphere via the air introducing portion 17b. Reference numeral 56 is a gold wire that electrically connects the gauge of the sensor chip 42 and the lead pin 49.

In such a semiconductor pressure sensor 6,
When the measured pressure P1 is introduced from one of the air introduction portions 17a to the surface of the pressure receiving diaphragm 44 and the atmospheric pressure P2 is introduced into the inner chamber 52, the pressure receiving diaphragm 44 is deformed according to the pressure difference, and the enclosed liquid 43 Strain generator 42 of sensor chip 42
Communicate to A. Therefore, the strain generating portion 42A is deformed to change the specific resistance of the gauge, and the measured pressure P1 or the differential pressure P1 is detected by detecting the output voltage accompanying the resistance change at this time.
-P2 can be measured. Then, this output voltage is fed back to the current-voltage converter 2 shown in FIG. 7 as a feedback signal and compared with the input signal I0. The pressure sensor 6 is not limited to the semiconductor pressure sensor and may be an electrostatic pressure sensor.

In this embodiment, the pressure sensor 6 is pressed against the air circuit forming member 15 by the bracket 11 and the tapered air introducing portions 17a and 17b are press-fitted into the through holes 33 of the seal member 32. ,
The air introduction portions 17a and 17b and the seal member 32 are in good contact with each other to obtain high sealing performance, and since the air introduction portions 17a and 17b are pressed against the seal member 32, there is no possibility of coming off. Therefore, the tubes 18a, 18b in the conventional mounting structure shown in FIG.
Does not require any joints 19 and clamps 20 and 21,
The number of parts can be reduced, which facilitates assembly work and maintenance. Further, since the tubes 18a and 18b are not used, it is not necessary to secure a piping space for the tubes, and space saving can be realized.

Further, since the annular bead 35 is integrally projected on the lower surface of the seal member 32 and the bead 35 is pressed against the inner bottom surface of the concave portion 34, the bracket 11 is fixed to the air circuit forming member 15 and the pressure sensor. When 6 is pressed against the seal member 32, the pressing force per unit area applied to the bead 35 is large, and the gap between the air passage hole 16a and the seal member 32 can be reliably sealed.

FIG. 4 is a sectional view of an air circuit forming member and a sealing member showing a second embodiment of the present invention. In this embodiment, instead of forming the beads on the seal member 32, the air passage holes 16 are formed on the surface of the air circuit forming member 15.
An annular bead 60 that surrounds a is projected integrally.

Even in such a structure, the pressing force applied to the bead 60 per unit area is large as in the above-described embodiment, and the gap between the air passage hole 16a and the seal member 32 can be reliably sealed. .

FIG. 5 is a sectional view of an air circuit forming member and a sealing member showing a third embodiment of the present invention. In this embodiment, a concave portion 62 having a taper communicating with the air passage hole 16a is formed on the surface of the air circuit forming member 15, the sealing member 32 is formed into a spherical body, and is fitted into the concave portion 62. There is.

In such a structure, when the bracket is fixed to the air circuit forming member 15 and the air introducing portion 17a of the pressure sensor is press-fitted into the through hole 33 of the seal member 32,
Since the seal member 32 is compressed by the tapered surface of the recess 62 and comes into close contact with the air introducing portion 17a, the space between the air introducing portion 17a and the through hole 33 can be more reliably sealed. Further, since the seal member 32 is brought into close contact with the tapered surface of the recess 62, the seal between the recess 62 and the seal member 32 is good, and the bead need not be provided. Further, since the recess 62 is tapered and the seal member 32 is formed into a spherical body, the seal member 32 can be stably installed in the recess 62.

FIG. 6 is a sectional view of an air circuit forming member and a sealing member showing a fourth embodiment of the present invention. In this embodiment, a circular recess 63 communicating with the air passage hole 16a is formed on the surface of the air circuit forming member 15, and the sealing member 32 is formed into a truncated cone shape. The hole diameter of the recess 63 is set to be larger than the outer diameter of the tip portion of the seal member 32 and smaller than the outer diameter of the base portion.

In such a structure, the seal member 3
When 2 is press-fitted into the recess 63, the seal member 32 can be compressed in the radial direction. Therefore, as in the third embodiment shown in FIG. 5, between the air introducing portion and the through hole 33 and the recess. It is possible to satisfactorily seal between 63 and the seal member 32.

[0038]

As described above, according to the pressure sensor mounting structure of the present invention, the air introducing portion of the pressure sensor is directly connected to the air passage hole through the cylindrical seal member. The number of parts can be reduced without the need for assembling parts such as tubes and clamps. Therefore, the manufacturing cost can be reduced, and the assembling work and maintenance are easy. Further, according to the present invention, since the pressure sensor is pressed against the air circuit forming member by the pressing member, the air introducing portion and the seal member and the seal member and the air circuit forming member can be surely brought into close contact with each other, and good sealing performance is achieved. Can be obtained.

Further, according to the present invention, since the bead is provided on the seal member or the air circuit forming member, it is possible to more reliably seal between the seal member and the air circuit forming member.

Further, according to the present invention, since the seal member is configured to be housed in the recess provided in the air circuit forming member, the seal member does not project to the surface of the air circuit forming member, and the air passage hole is formed in the air passage forming member. It can be positioned reliably.

Further, according to the present invention, since the taper portion is formed in the concave portion and the sealing member is formed in the spherical shape or the truncated cone shape, the sealing member can be surely brought into close contact with the concave portion, and moreover, the sealing member. Since the air is compressed, the air introduction portion and the sealing member are also brought into close contact with each other, and the sealing performance can be further improved. Further, since the tube is unnecessary, it is not necessary to secure the space, and the size of the converter itself can be reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of a pressure sensor mounting structure according to the present invention.

FIG. 2 is a sectional view of a seal member. It is a top view of a seal member.

FIG. 3 is a sectional view of a semiconductor pressure sensor.

FIG. 4 is a cross-sectional view of an air circuit forming member and a sealing member showing a second embodiment of the present invention.

FIG. 5 is a cross-sectional view of an air circuit forming member and a sealing member showing a third embodiment of the present invention.

FIG. 6 is a cross-sectional view of an air circuit forming member and a sealing member showing a fourth embodiment of the present invention. It is sectional drawing which shows other embodiment of this invention.

FIG. 7 is a block diagram showing a basic configuration of a valve positioner.

FIG. 8 is a cross-sectional view showing a conventional pressure sensor mounting structure.

[Explanation of symbols]

6 ... Pressure sensor, 10 ... Printed wiring board, 11 ... Bracket, 16a, 16b ... Air circuit hole, 17a, 17b
... Air introduction part, 32 ... Seal member, 33 ... Through hole, 35
... beads, 60 ... beads, 62, 63 ... recesses.

Continuation of the front page (56) Reference JP-A-7-209119 (JP, A) JP-A-4-185901 (JP, A) Actually opened 63-72537 (JP, U) Actually opened 63-62740 (JP , U) Actual exploitation Sho 59-135654 (JP, U) Actual exploitation Sho 58-7963 (JP, U) Japanese Patent Publication Sho 58-47013 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB) Name) G01L 9/00 303 G01D 11/30 G01L 19/00 G12B 9/08

Claims (5)

(57) [Claims] 1. An air circuit forming member having an air passage hole, a pressure sensor having an air introducing portion, a tubular seal member having a through hole, and the pressure sensor forming the air circuit via the seal member. A pressing member for pressing the air passage hole and the air introducing portion to communicate with each other through the through hole, forming a taper on the air introducing portion of the pressure sensor, and pressing the through hole of the sealing member. A pressure sensor mounting structure characterized by being press-fitted by a member. 2. The pressure sensor mounting structure according to claim 1, wherein an annular bead that surrounds the air passage hole or the through hole is integrally provided on one of the joint surfaces of the seal member and the air circuit forming member. The pressure sensor mounting structure is characterized in that 3. The pressure sensor mounting structure according to claim 1, wherein a recess communicating with the air passage hole is formed on the surface of the air circuit forming member, and the seal member is fitted in the recess. The pressure sensor mounting structure. 4. The mounting structure for a pressure sensor according to claim 3, wherein the recess of the air circuit forming member is formed as a recess having a taper that expands toward the pressure sensor, and the sealing member is formed as a spherical body. Characteristic pressure sensor mounting structure. 5. The mounting structure for a pressure sensor according to claim 3 , wherein the recess of the air circuit forming member is formed in a circular shape having a constant hole diameter.
A mounting structure for a pressure sensor, characterized in that the sealing member is formed in a truncated cone shape.