JPH0534550U - Pressure sensor - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a pressure sensor with reduced number of parts and easy to manufacture. [Structure] A metal diaphragm 16 and a circuit board 17 are arranged in a case 11 having a pressure introducing port 18. The metal diaphragm 16 is fixed to the case 1 via the stand 12. At this time, the respective joints are welded with an electron beam. In the stand 12, one mounting portion and the other mounting portion are connected by a thin tubular connecting portion, and a communication hole penetrates inside. The pressure introducing port 18 is electrically connected to the metal diaphragm 16 via the communication hole of the stand 12. The circuit board 17 is positioned substantially on the same plane as the metal diaphragm 16, and the two are directly connected. With the above configuration, it is possible to eliminate the components such as the O-ring, the backup ring, the stop ring, and the flexible circuit which are conventionally required.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a pressure sensor, for example, a pressure sensor used for measuring the pressure of liquid, gas and the like.

[0002]

[Prior art and its problems]

 Conventionally, a pressure sensor as shown in FIG. 4 has been known as a pressure sensor which detects an acting pressure and outputs an electric signal corresponding to the pressure.

That is, in the pressure sensor shown in FIG. 4, the metal diaphragm 26 and the circuit board 27 are arranged in the case 21 having the pressure introducing port 28, and when the pressure is introduced from the pressure introducing port 28, The pressure is converted into an electric signal by the sensor formed on the metal diaphragm 26, the electric signal generated in the sensor is amplified by the circuit board 27, and then the electric signal is output to the outside. ing.

In FIG. 3, the case 21 has a void therein and a pressure introducing port 28 for connecting the inside void and the outside is formed, and the inside void of the case 21 is made of metal. The diaphragm 26 and the circuit board 27 are arranged.

The metal diaphragm 26 is disposed in the inner space of the case 1 so as to face the pressure introducing port 28, and has a central portion formed thin to form a pressure receiving portion. Displacement is possible in the axial direction according to the pressure introduced from 28.

A strain gauge (not shown), which is a sensor, is formed in a film shape on the pressure receiving portion of the metal diaphragm 26. When the pressure receiving portion of the metal diaphragm 26 is displaced, the resistance value inside the strain gauge changes. By doing so, the displacement amount of the pressure receiving portion of the metal diaphragm 26 is converted as the variation amount of the resistance value of the strain gauge.

The metal diaphragm 26 is fixed by being caulked by a part of the case 1 in a state where the upper end peripheral portion of the metal diaphragm 26 is pressed by the annular stop ring 31. At this time, in order to prevent internal stress from remaining in the metal diaphragm 26 due to the caulking force, an annular backup ring 30 and an O-ring 33 are provided between the bottom surface of the metal diaphragm 26 and the case 21. Then, when a caulking force exceeding the design value is applied to the metal diaphragm 26, the extra caulking force is absorbed by the backup ring 30 and the O ring 33.

The strain gauge formed on the metal diaphragm 26 is electrically connected to the circuit board 27 arranged above the metal diaphragm 26 via the flexible circuit 32. An amplifier circuit is built on this circuit board 27, and an electric signal sent through the flexible circuit 32, that is, a signal generated by a change in the resistance value of the strain gauge on the metal diaphragm 26 is It is adapted to be amplified by the circuit board 27.

A terminal 40 is connected to the circuit board 27, and the electric signal amplified by the circuit board 27 is output to the outside of the case 21 via the terminal 40.

Reference numeral 33 is an O-ring, and the O-ring 33 seals between the metal diaphragm 26 and the case 21. A potting agent 29 is filled in the space between the circuit board 27 and the metal diaphragm 26.

With this configuration, when pressure is introduced from the pressure inlet port 28, the pressure sensor causes the metal diaphragm 26 to be displaced by the action of the pressure, and the resistance value of the sensor on the metal diaphragm 26. Will change.

Then, due to the change in the resistance value of the sensor, the introduced pressure is converted into an electric signal, and this electric signal is guided to the circuit board 27 via the flexible circuit 32. Further, the electric signal sent from the flexible circuit 32 is amplified by the circuit board 27 and then output to the outside via the terminal 40.

However, such a conventional pressure sensor is complicated because the number of parts in the case is large, and assembly of parts in the case is troublesome, which is a problem.

The present invention solves the above problems, and an object of the present invention is to provide a pressure sensor that can reduce the number of parts in a case and can be easily manufactured.

[0015]

[Means for solving problems]

 In order to solve the above-mentioned problems, this invention arranges a metal diaphragm and a circuit board in a case having a pressure introducing port, detects the pressure introduced from the pressure introducing port, Further, in the pressure sensor which is adapted to output to the outside as an electric signal, a means is adopted in which the metal diaphragm is welded to the case with its pressure receiving portion facing the pressure inlet of the case. Is. In addition, a metal diaphragm and a circuit board are arranged in a case having a pressure introducing port to detect the pressure introduced from the pressure introducing port, and further to output it as an electric signal to the outside. The sensor employs a means in which the metal diaphragm is fixed to the case via a stand. Further, the stand is connected by a thin-walled connecting portion having a tubular shape between one mounting portion for mounting the metal diaphragm and the other mounting portion for mounting the metal diaphragm, and the inside of the stand is A communication hole for aligning the axis with the connecting portion is penetrated, one opening of the communication hole on the side of the mounting portion is on the metal diaphragm side, and the other opening of the communication hole on the side of the mounting portion is on the pressure introducing side. It is fixed to the case in a state where it is opened to the mouth side, whereby the pressure introducing port is adapted to be electrically connected to the metal diaphragm side through the communication hole of the stand. Further, the metal diaphragm and the stand and the stand and the case are welded by irradiating them with an electron beam, and the metal diaphragm and the circuit board are connected by wire bonding. It is a method adopted.

[0016]

[Action]

 By adopting the above means, this invention can fix the metal diaphragm to the case without using a caulking means. This makes it possible to eliminate the parts that were conventionally required to fix the metal diaphragm to the case, such as the O-ring, backup ring, and stop ring.

Further, in the stand, since the attaching portion for attaching the metal diaphragm and the attaching portion for attaching to the case are connected by the thin connecting portion, the metal diaphragm and the stand, or the stand and Even when different metals are used for the case and the case is joined, the stand connection part absorbs the thermal stress caused by the difference in the linear expansion coefficient peculiar to each material. This suppresses the thermal stress generated on the surface of the metal diaphragm in particular, and does not affect the pressure measurement.

[0018]

【Example】

 Embodiments of the present invention shown in the drawings will be described below. FIG. 1 is a diagram showing a first embodiment of the present invention. That is, in the pressure sensor shown in FIG. 1, the metal diaphragm 6 and the circuit board 7 are arranged in the case 1 having the pressure introducing port 8, and when the pressure is introduced from the pressure introducing port 8, the pressure is detected as an electric signal. Further, this electric signal is amplified by the circuit board 7 and then outputted to the outside. The metal diaphragm 6 is welded and fixed directly to the case 1.

In FIG. 1, the case 1 is made of metal, has a void inside, and is formed with a pressure introducing port 8 for connecting the inside void to the outside. The metal diaphragm 6 and the circuit board 7 are arranged in the inner space of the space 1.

The central portion of the metal diaphragm 6 is formed thin so as to form a pressure receiving portion. In the inner space of the case 1, the pressure receiving portion faces the pressure introducing port 8 and faces the pressure introducing port 8. By being arranged, the pressure receiving portion is displaced in the axial direction according to the pressure force introduced from the pressure introducing port 8.

At this time, the bottom surface of the metal diaphragm 6 is joined to the bottom portion of the inner space of the case 1, and the joint portion between the two is welded and fixed by, for example, irradiating an electron beam. To do so.

Although not shown, a strain gauge, which is a sensor, is formed in a film shape on the pressure receiving portion of the metal diaphragm 6, and when the pressure receiving portion of the metal diaphragm 6 is displaced, the strain gauge is changed to the metal diaphragm 6. With this, the internal resistance value changes due to the displacement, and the displacement amount of the pressure receiving portion of the metal diaphragm 6 is converted as the change amount of the resistance value of the strain gauge.

An annular circuit board 7 is disposed between the case 1 and the metal diaphragm 6 at a position substantially flush with the upper end surface of the metal diaphragm 6. Then, the circuit on the circuit board 7 and the strain gauge on the metal diaphragm 6 are directly connected by means such as wire bonding.

An amplifier circuit is built on the circuit board 7, and an electric signal obtained by changing the resistance value of the strain gauge on the metal diaphragm 6 is amplified by the circuit on the circuit board 7. It is supposed to be done.

A terminal 10 is further connected to the circuit board 7, and the electric signal amplified by the circuit board 7 is output to the outside of the case 1 via the terminal 10. In addition, 9 is a potting agent.

Next, the operation of the above will be described. With this pressure sensor configured as described above, when pressure is introduced from the pressure introducing port 8, the pressure acts on the pressure receiving portion of the metal diaphragm 6, and this pressure receiving portion causes a large amount of the introduced pressure. It will be displaced accordingly. When the metal diaphragm 6 is displaced in this way, the resistance value of the strain gauge on the metal diaphragm 6 changes, and the introduction of pressure is detected as an electric signal. Then, this electric signal is guided to the circuit board 7, amplified, and then output to the outside through the terminal 10.

Since the metal diaphragm 6 is directly welded to the case 1, parts such as an O-ring, a backup ring, and a stop ring, which are conventionally required to fix the metal diaphragm, can be eliminated. become able to.

Further, since the metal diaphragm 6 and the circuit board 7 are directly connected, there is no need to connect them using a flexible circuit as in the conventional case, and the number of parts in the case can be reduced. You can do it.

FIG. 2 shows a second embodiment of the present invention. In the pressure sensor shown in FIG. 2, the metal diaphragm 16 and the circuit board 17 are arranged in the case 11 having the pressure introducing port 18. When pressure is introduced from the pressure introducing port 18, the pressure sensor is formed on the metal diaphragm 16. The pressure introduced by the sensor is detected as an electric signal, and the electric signal is amplified by the circuit board 17 and then output to the outside. The metal diaphragm 16 is a stand. It is fixed to the case 11 via 12 and the sensor of the metal diaphragm 16 and the circuit board 17 are directly connected.

In FIG. 2, the case 11 is made of metal, has a void inside, and is formed with a pressure introducing port 18 for connecting the inside void to the outside. The metal diaphragm 16 and the circuit board 17 are arranged in the inner space of the.

The metal diaphragm 16 is arranged in the inner space of the case 11 so as to face the pressure introducing port 18, and the pressure receiving portion is formed by forming the central portion thin. The pressure receiving portion is configured to be displaced in the axial direction according to the pressure introduced from the pressure introducing port 18.

A strain gauge (not shown), which is a sensor, is formed in a film shape on the pressure receiving portion of the metal diaphragm 16. When the pressure receiving portion of the metal diaphragm 16 is displaced, the strain gauge is displaced together with the metal diaphragm 16. The internal resistance value of the strain gauge changes so that the displacement amount of the pressure receiving portion of the metal diaphragm 16 is converted into the change amount of the resistance value of the strain gauge.

As shown in FIG. 3, the metal diaphragm 16 is integrally fixed to the case 11 via the stand 12. In the stand 12, one mounting portion 15 for mounting the metal diaphragm 16 and the other mounting portion 13 for mounting on the case 11 are connected by a thin cylindrical connecting portion 14. A communication hole 12a is formed in each of the upper and lower end surfaces of the stand 12 so as to pass through the inside of the stand 12 in alignment with the axis of the connecting portion.

One mounting portion 15 of the stand 12 is formed in a disc shape so as to match the shape of the bottom portion of the metal diaphragm 16, and the upper end surface of the mounting portion 15 and the bottom surface of the metal die diaphragm 16 are connected to each other. After joining, the electron beam is irradiated from the outer peripheral side of this joining portion in the axial direction (direction A in FIG. 3) so that the two are welded and the metal diaphragm 16 is fixed to the stand 12. I have to.

The other mounting portion 13 of the stand 12 is formed in a disc shape so as to match a part of the bottom of the internal space of the case 11, and the mounting portion 13 is mounted on one part of the case 11. Then, the joint portion between the mounting portion 13 and the case 11 is irradiated with an electron beam from above (in the direction B in FIG. 3) to weld the two and fix the stand 12 to the case 11. I am trying to do it.

At this time, the opening of the communication hole 12a of the stand 12 on the side of the one mounting portion 15 is positioned so as to face the pressure receiving portion of the metal diaphragm 16, and the other mounting portion 13 of the communication hole 12a is positioned. The opening on the side is located so as to face the pressure introducing port 18 of the case 11 so that the pressure introducing port 18 is electrically connected to the pressure receiving part of the metal diaphragm 16 via the communication hole 12a of the stand 12. ..

An annular circuit board 17 is provided between the case 11 and the metal diaphragm 16 so as to be substantially flush with the upper end surface of the metal diaphragm 16. Then, the circuit on the circuit board 17 and the strain gauge on the metal diaphragm 16 are directly connected by means such as wire bonding.

An amplification circuit is built on the circuit board 17 so that an electric signal generated when the resistance value of the strain gauge on the metal diaphragm 16 changes is amplified by the circuit on the circuit board 17. It has become.

A terminal 20 is further connected to the circuit board 17, and the electric signal amplified by the circuit board 17 is output to the outside of the case 11 via the terminal 20.

A potting agent 19 is filled in a space surrounded by the circuit board 17, the metal diaphragm 16, the stand 12, and the case 11.

Next, the operation of the above will be described. With this pressure sensor configured as described above, when pressure is introduced from the pressure introducing port 18, the pressure acts on the pressure receiving portion of the metal diaphragm 16 through the communication hole 12a of the stand 12 and the metal diaphragm. 16 becomes displaced according to the magnitude of the pressure introduced. When the metal diaphragm 16 is thus displaced, the resistance value of the sensor on the metal diaphragm 16 changes, and the introduction of pressure is detected as an electric signal. Then, this electric signal is guided to the circuit board 17, the signal is amplified, and then outputted to the outside through the terminal 20.

Since the joining portion between the stand 12 and the metal diaphragm 16 and the joining portion between the stand 12 and the case 11 are arranged to be welded by irradiating an electron beam, they are formed on the metal diaphragm 16 at the time of welding. The thermal effect on the strain gauge can be relatively suppressed.

At the same time, the welding by the electron beam enables the joining even if the stand 12, the metal diaphragm 16, and the case 11 are made of different kinds of metal, and at the same time, can sufficiently maintain the sealing property. It has become.

Further, even when the metal diaphragm 16 and the stand 12 or the stand 12 and the case 11 are made of different metals, the stress due to heat is suppressed after joining them.

That is, when the metal diaphragm 16 and the stand 12 or the stand 12 and the case 11 are made of different metals, heat is usually applied due to the difference in linear expansion coefficient between the two. Although stress is generated at this time, since the connecting portion 14 of the stand 12 is formed thin, the connecting portion 14 absorbs the stress due to heat.

In particular, when a stress due to heat is generated in the metal diaphragm 16, the pressure cannot be measured accurately, so the stress is absorbed by the deformation of the connecting portion 14 of the stand 12, and the stress is measured by the pressure. It is blocking the influence.

As described above, since the metal diaphragm 16 is fixed to the case 11 via the stand 12 by welding, the stop ring that is conventionally required when fixing the metal diaphragm to the case by caulking the metal diaphragm. , O-ring and back-up ring can be eliminated.

Further, since the metal diaphragm 16 and the circuit board 17 are arranged so as to be located at substantially the same height, the wires can be directly connected by wire bonding, and thus they are conventional connecting parts. The flexible circuit can be eliminated, which facilitates wiring work inside the case.

[0049]

[Effect of the device]

 As described above, according to the present invention, the metal diaphragm is fixed to the case directly or through the stand. Therefore, the O-ring and the backup ring that were conventionally required when fixing the metal diaphragm to the case were used. It is possible to eliminate the need for parts such as a stop ring and reduce the number of parts.

Further, since the metal diaphragm and the circuit board are directly connected to each other, it becomes possible to dispense with the flexible circuit which has conventionally connected the two.

With such a reduction in the number of parts, the structure inside the case is simplified, which has the effect of facilitating the manufacture of the pressure sensor.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a second embodiment of the present invention.

FIG. 3 is a diagram illustrating a main part of FIG.

FIG. 4 is a diagram showing a conventional example.

[Explanation of symbols]

 1,11,21 ………… Case 12 ………… Stand 13,15 ………… Mounting part 14 ………… Connecting part 12a ………… Communication hole 6,16,26 ………… Metal diaphragm 7, 17, 27 ...... Circuit board 8, 18, 28 ...... Pressure inlet 9, 19, 29 ...... Potting agent 10, 20, 40 ...... Terminal 30 ...... Backup Ring 31 ………… Stop ring 32 ………… Flexible circuit 33 ………… O ring

Claims (5)

[Scope of utility model registration request] 1. A metal diaphragm (6) (1) is provided in a case (1) (11) having pressure inlets (8) (18).
6) and the circuit boards (7) and (17) are arranged to detect the pressure introduced from the pressure inlets (8) and (18),
Further, in the pressure sensor which is designed to output to the outside as an electric signal, the metal diaphragm (6) (1
6) with the pressure receiving portion facing the pressure introducing ports (8) and (18) of the cases (1) and (11).
A pressure sensor characterized by being welded to (11). 2. A case (1) having a pressure inlet (18)
A metal diaphragm (16) and a circuit board (17) are arranged in 1) to detect the pressure introduced from the pressure inlet (18) and further output it as an electric signal to the outside. The pressure sensor according to claim 1, wherein the metal diaphragm (16) is fixed to the case (11) via a stand (12). 3. The stand (12) has one mounting portion (1) for mounting the metal diaphragm (16).
5) and a thin connecting portion (14) having a tubular shape between the other attaching portion (13) for attaching to the case (11).
And a communication hole (12a) for aligning the axis with the connection portion (14) penetrates through the inside of the connection hole (12a), and the opening on one side of the attachment portion (15) of the communication hole (12a) is connected to On the metal diaphragm (16) side, the communication hole (12
The opening on the side of the other mounting portion (13) of (a) is fixed to the case (11) with the opening on the side of the pressure introducing port (18), so that the pressure introducing port (18) can be fixed to the stand ( 3. The pressure sensor according to claim 2, wherein the pressure sensor is electrically connected to the metal diaphragm (16) side through the communication hole (12a) of 12). 4. The electron beam is radiated and welded between the metal diaphragm (16) and the stand (12) and between the stand (12) and the case (11). Pressure sensor. 5. The pressure sensor according to claim 1, wherein the metal diaphragm (6) (16) and the circuit board (7) (17) are connected by wire bonding.