JP2020187047A - Pressure sensor - Google Patents

Abstract

To provide a pressure sensor which can reduce influence of heat on a sensor element.SOLUTION: The present invention includes a body 3, which contains a closed space 18 and includes a sensor element 15 in the closed space 18, the sensor element obtaining a signal according to a detected pressure. The present invention also includes: a lower-pressure side pressure guiding pipe 25 and a higher-pressure side pressure guiding pipe 26, which support the sensor element 15 and function as a part of a pressure guiding path for transmitting a pressure to the sensor element 15. The closed space 18 is in a vacuum state, or is filled with an inert gas, or is filled with air.SELECTED DRAWING: Figure 1

Description

The present invention relates to a pressure sensor.

Technology related to differential pressure transmitters has been developed. Examples of the above-mentioned technique include the technique described in Patent Document 1.

JP 2015-194343

For example, in a pressure sensor that detects pressure, such as the differential pressure transmitter described in Patent Document 1, it is required to suppress the influence of heat on the sensor element (or sensor chip).

An object of the present invention is to provide a pressure sensor capable of suppressing the influence of heat on a sensor element.

In order to achieve this object, the pressure sensor according to the present invention has a body having a closed space inside and a sensor element for obtaining a signal corresponding to the detected pressure is arranged in the closed space, and the sensor element. It comprises a pressure guiding pipe that supports and functions as part of a pressure guiding path that transmits pressure to the sensor element, and the closed space is in a vacuum state, filled with an inert gas, or in air. It is in a state of being satisfied.

In the present invention, in the pressure sensor, the sensor element may be arranged apart from the boundary of the closed space.

In the present invention, in the pressure sensor, the sensor element may be arranged so that a part of the sensor element is in contact with the boundary of the closed space.

According to the present invention, in the pressure sensor, the pressure guiding pipe transmits a first pressure guiding pipe and a second pressure guiding pipe that functions as a part of a first pressure guiding path for transmitting the first pressure. A second pressure guiding pipe that functions as a part of the pressure guiding path 2 is included, and the sensor element obtains a signal corresponding to a differential pressure between the first pressure and the second pressure. There may be.

According to the present invention, it is possible to suppress the influence of heat on the sensor element.

It is sectional drawing which shows the schematic structure of the differential pressure transmitter equipped with the pressure sensor which concerns on this invention. It is sectional drawing which shows the main part enlarged. It is sectional drawing which shows the other embodiment. It is sectional drawing which shows the other embodiment. It is sectional drawing which shows the other embodiment.

(First Embodiment)
Hereinafter, an embodiment of the pressure sensor according to the present invention will be described in detail with reference to FIGS. 1 and 2. In this embodiment, an example of mounting the pressure sensor according to the present invention on the differential pressure transmitter will be described.

The differential pressure transmitter 1 shown in FIG. 1 includes a body 3 for accommodating the pressure sensor 2 according to the present invention, and a cylindrical cover 4. The body 3 is fixed to the cover 4 in a state where the central portion is fitted to one end portion (lower end portion in FIG. 1) of the cover 4. Therefore, one end of the cylindrical cover 4 is closed by the body 3. The body 3 and the cover 4 are made of a metal material such as stainless steel.

The body 3 has a low-pressure side liquid contact portion 5 located on the left side in FIG. 1 and a high-pressure side liquid contact portion 6 located on the right side in FIG. The low-pressure side liquid contact portion 5 is provided with a low-pressure side pressure receiving chamber 8 so that the low-pressure side barrier diaphragm 7 becomes a part of the wall. The high-pressure side liquid contact portion 6 is provided with a high-pressure side pressure receiving chamber 10 so that the high-pressure side barrier diaphragm 9 becomes a part of the wall. The low pressure side barrier diaphragm 7 and the high pressure side barrier diaphragm 9 are pushed and displaced by the pressure of the fluid to be measured (not shown).

The low-pressure side pressure receiving chamber 8 is connected to the pressure sensor 2 via a first pressure guiding path 11 formed in the body 3 and the cover 4. The high-pressure side pressure receiving chamber 10 is connected to the pressure sensor 2 via a second pressure guiding path 12 formed in the body 3 and the cover 4. The first pressure guiding path 11 and the second pressure guiding path 12 are each filled with a pressure transmission medium 13.

The pressure sensor 2 has a housing 14 that fits in the hollow portion 4a of the cover 4, and a sensor element 15 housed in the housing 14. The housing 14 is composed of a sensor header 16 formed in a bottomed cylindrical shape and a lid 17 that closes an opening of the sensor header 16. The sensor header 16 and the lid 17 are also made of a metal material such as stainless steel. A closed space 18 closed by a lid 17 is formed in the sensor header 16. The sensor header 16 is fitted to the body 3 and the cover 4 with the bottom portion 16a facing the body 3, and is fixed to the body 3 and the cover 4 so as to be liquid-tight. The lid 17 is fitted into the opening 16b of the sensor header 16 and fixed so as to be airtight.

The sensor header 16 includes a third pressure guiding path 21 connected to the first pressure guiding path 11 described above and a fourth pressure guiding path 22 connected to the second pressure guiding path 12 described above. It is formed. In this embodiment, since the first pressure guiding path 11 is formed in the fitting portion between the cover 4 and the sensor header 16, the third pressure guiding path 21 is from the outer peripheral surface of the sensor header 16. It is formed so as to extend toward the axial center of the sensor header 16. Further, in this embodiment, since the second pressure guiding path 12 is formed between the bottom portion 16a of the sensor header 16 and the body 3, the fourth pressure guiding path 22 is the bottom portion of the sensor header 16. It extends in the axial direction in 16a. The third pressure guiding path 21 and the fourth pressure guiding path 22 are filled with the pressure transmission medium 13.

The first pressure guiding path 11 and the third pressure guiding path 21 constitute a low pressure side pressure guiding path 23 for transmitting pressure from the low pressure side liquid contact portion 5 by the pressure transmission medium 13. On the other hand, the second pressure guiding path 12 and the fourth pressure guiding path 22 form a high pressure side pressure guiding path 24 for transmitting pressure from the high pressure side liquid contact portion 6 by the pressure transmission medium 13.

At the bottom 16a of the sensor header 16 and at the center in the radial direction, a low pressure side pressure guiding pipe 25 and a high pressure side pressure guiding pipe 26 are provided so as to extend in the axial direction of the sensor header 16, respectively. The low pressure side pressure guiding pipe 25 and the high pressure side pressure guiding pipe 26 are each made of a metal material such as stainless steel. The low pressure side pressure guiding pipe 25 and the high pressure side pressure guiding pipe 26 function as a part of the pressure guiding path for transmitting the pressure to the pressure sensor 2. The low-pressure side pressure guiding pipe 25 has one end connected to the third pressure guiding path 21 and the other end facing the closed space 18. The high-pressure side pressure guiding pipe 26 has one end connected to the fourth pressure guiding path 22 and the other end facing the closed space 18. The low pressure side pressure guiding pipe 25 is filled with the pressure transmission medium 13 and pressure is transmitted from the low pressure side pressure guiding passage 23. The high pressure side pressure guiding pipe 26 is filled with the pressure transmission medium 13 and pressure is transmitted from the high pressure side pressure guiding path 24. As shown in FIG. 2, the low-pressure side pressure guiding pipe 25 and the high-pressure side pressure guiding pipe 26 are respectively adhered to the sensor header 16 by an adhesive 27.

The sensor element 15 is connected to the other end of the low pressure side pressure guiding pipe 25 and the other end of the high pressure side pressure guiding pipe 26. In the sensor element 15, the pressure of the low pressure side liquid contact portion 5 is transmitted through the low pressure side pressure guiding path 23 and the low pressure side pressure guiding pipe 25, and the pressure of the high pressure side liquid contact portion 6 is transmitted to the high pressure side pressure guiding path. It is transmitted via the 24 and the high pressure side pressure guiding pipe 26. In this embodiment, one of the low pressure side pressure guiding pipe 25 and the high pressure side pressure guiding pipe 26 has the "first pressure guiding that transmits the first pressure" according to the invention of claim 4. Corresponding to the "first pressure guiding pipe that functions as a part of the path", the other pipe functions as a part of the "second pressure guiding path that transmits the second pressure" according to the invention of claim 4. It corresponds to the "second pressure guiding pipe".

Although not shown, a sensor diaphragm is provided inside the sensor element 15 to which the pressure of the low-pressure side wetted portion 5 and the pressure of the high-pressure side wetted portion 6 are applied. The sensor element 15 converts the displacement of the sensor diaphragm into an electric signal, and outputs a signal corresponding to the pressure difference between the pressure of the low-pressure side wetted portion 5 and the pressure of the high-pressure side wetted portion 6. The material that forms the sensor element 15 including this sensor diaphragm is silicon.

The sensor element 15 is housed in a closed space 18 in the sensor header 16 and is supported by the sensor header 16 via the low pressure side pressure guiding pipe 25 and the high pressure side pressure guiding pipe 26. The sensor element 15 according to this embodiment is positioned at the center of the closed space 18 so as to be separated from the bottom wall 18a (see FIG. 2) and the side wall 18b of the closed space 18, and is separated from the low pressure side pressure guiding pipe 25 and the high pressure. It is supported by the sensor header 16 only via the side pressure guiding pipe 26. In this embodiment, the bottom wall 18a and the side wall 18b correspond to the "boundary of the closed space" in the invention according to claim 2.

In addition to the sensor element 15, the closed space 18 accommodates a support member 31, a flexible wiring board 32, and the like. The support member 31 fixes one end of the flexible wiring board 32 to the sensor header 16. One end of the flexible wiring board 32 is electrically connected to an output terminal (not shown) of the sensor element 15 via a bonding wire (not shown). An external output pin 33 is electrically connected to the other end of the flexible wiring board 32. The external output pin 33 is supported by the lid 17 in a state of penetrating the lid 17.

The closed space 18 is sealed with a predetermined atmosphere in a state where the sensor element 15 and the flexible wiring board 32 are housed. The lid 17 is formed with a through hole 34 for discharging air when the inside of the closed space 18 has a predetermined atmosphere. The through hole 34 is closed by the sealing material 35 after the inside of the closed space 18 has a predetermined atmosphere. In this embodiment, the predetermined atmosphere means that the inside of the closed space 18 is in a vacuum state, a state of being filled with nitrogen gas or other inert gas, or a state of being filled with air. In sealing the closed space 18, the sealing material 35 is welded to the lid 17 by resistance welding or laser welding, or the lid 17 having no through hole 34 is resistance welded to the sensor header 16. Can be done by welding. Further, even if a seal structure having an O-ring or the like is provided between the lid 17 having no through hole 34 and the sensor header 16, or the lid 17 is adhered to the sensor header 16 with an adhesive, the closed space 18 is formed. Can be sealed.

The body 3 and the cover 4 of the differential pressure transmitter 1 according to this embodiment may be heated by the heat of the fluid to be measured, the heat of the usage environment, or the like. This heat is directly transmitted to the housing 14 of the pressure sensor 2 and also indirectly transmitted through the pressure transmission medium 13. However, in the pressure sensor 2, since the sensor element 15 is supported by the low pressure side pressure guiding pipe 25 and the high pressure side pressure guiding pipe 26 in the housing 14 (sensor header 16), the heat of the housing 14 and the heat of the pressure transfer medium 13 are transferred. It is transmitted to the sensor element 15 via the low pressure side pressure guiding pipe 25 and the high pressure side pressure guiding pipe 26. Therefore, according to this embodiment, it is possible to provide a pressure sensor capable of suppressing the influence of heat on the sensor element.

The sensor element 15 according to this embodiment is supported only by the low pressure side pressure guiding pipe 25 and the high pressure side pressure guiding pipe 26, and is separated from the bottom wall 18a and the side wall 18b of the closed space 18. Therefore, heat is more difficult to be transferred to the sensor element 15, and a pressure sensor having high heat resistance can be realized.

The closed space 18 according to this embodiment is sealed in a vacuum state. Therefore, since the temperature in the closed space 18 does not rise, the temperature of the pressure sensor 2 can be kept even lower.

In this embodiment, the pressure guiding path for guiding the pressure to the pressure sensor 2 is composed of the low pressure side pressure guiding path 23 and the high pressure side pressure guiding path 24. The pressure sensor 2 has a low pressure side pressure guiding pipe 25 connected to the low pressure side pressure guiding path 23 and a high pressure side pressure guiding pipe 26 connected to the high pressure side pressure guiding path 24. The differential pressure between the pressure transmitted by 25 and the pressure transmitted by the high pressure side pressure guiding pipe 26 is detected. Therefore, according to this embodiment, it is possible to provide a differential pressure sensor having high heat resistance.

(Second Embodiment)
The positions where the low-pressure side pressure guiding pipe 25 and the high-pressure side pressure guiding pipe 26 are connected to the sensor element 15 can be appropriately changed. The low-pressure side pressure guiding pipe 25 and the high-pressure side pressure guiding pipe 26 can be connected to positions such that the sensor element 15 is sandwiched between them, for example, as shown in FIG. In FIG. 3, the same or equivalent members as those described with reference to FIGS. 1 and 2 are designated by the same reference numerals, and detailed description thereof will be omitted as appropriate. FIG. 3 is drawn by omitting members such as a lid 17 that closes the closed space 18 and a flexible wiring board 32 housed in the closed space 18.

The sensor element 15 shown in FIG. 3 is housed in a closed space 18 of a housing 14 including a body 3 and a tubular cover 4. The low-voltage side pressure guiding pipe 25 extends from one side portion 15a of the sensor element 15 located on the left side in FIG. 3 toward one side and is bent in the middle, and the cover 4 is formed between the cover 4 and the sensor element 15. It extends in the axial direction (vertical direction in FIG. 3) and is connected to the low-voltage side pressure guiding path 23 in the body 3.

The high-pressure side pressure guiding pipe 26 extends from the other side portion 15b of the sensor element 15 located on the right side in FIG. 3 toward the other side and is bent in the middle, and the cover 4 is formed between the cover 4 and the sensor element 15. It extends in the axial direction and is connected to the high-pressure side pressure guiding path 24 in the body 3.
In this embodiment, the sensor element 15 is supported from both sides by the low pressure side pressure guiding pipe 25 and the high pressure side pressure guiding pipe 26. Therefore, the sensor element 15 can be supported more firmly than in the case where one side portion of the sensor element 15 is supported by the low-pressure side and high-pressure side pressure guiding pipes 26 as in the case of adopting the first embodiment. become.

(Third Embodiment)
The structure of the portion that extracts the detection signal from the sensor element 15 is not limited to the flexible wiring board 32, and can be appropriately changed. The detection signal of the sensor element 15 can be taken out by using the lead pin 41 as shown in FIG. 4, or can be taken out by using a printed circuit board, a lead wire, or the like, although not shown. In FIG. 4, the same or equivalent members as those described with reference to FIGS. 1 and 2 are designated by the same reference numerals, and detailed description thereof will be omitted as appropriate.

The lead pin 41 shown in FIG. 4 is provided upright on a relay plate 42 provided on the bottom wall 18a of the closed space 18, penetrates the lid 17, and is led out to the outside of the housing 14. The lead pin 41 is connected to the output terminal (not shown) of the sensor element 15 by a wiring (not shown) on the relay plate 42 and a bonding wire 43 or the like.

(Fourth Embodiment)
As shown in FIG. 5, the sensor element 15 can be arranged close to the bottom wall 18a of the closed space 18 in addition to the low pressure side pressure guiding pipe 25 and the high pressure side pressure guiding pipe 26. In FIG. 5, the same or equivalent members as those described with reference to FIGS. 1 and 2 are designated by the same reference numerals, and detailed description thereof will be omitted as appropriate.

The sensor header 16 shown in FIG. 5 has a recess 51 that opens into the bottom wall 18a of the closed space 18. The low pressure side pressure guiding pipe 25 and the high pressure side pressure guiding pipe 26 are passed through the recess 51 to connect the sensor header 16 and the sensor element 15. The opening width of the recess 51 is narrower than the width of the sensor element 15. The sensor element 15 is fixed to the opening edge of the recess 51 by an adhesive 52. The adhesive 52 is applied to a plurality of portions of the sensor element 15. Therefore, a part of the sensor element 15 is arranged so as to be in contact with the boundary of the closed space 18, and is fixed to the sensor header 16 so that the heat transfer path made of the adhesive 52 is reduced as much as possible.

By adopting the form shown in FIG. 5, since the support of the sensor element 15 is stable, the work of bonding the bonding wire to the output terminal (not shown) of the sensor element 15 can be easily performed. Therefore, according to this embodiment, it is possible to provide a pressure sensor having excellent heat resistance and assembling property.

The embodiments of the present invention have been described in detail with reference to the accompanying drawings. However, the technical scope of the present invention is not limited to such examples. It is clear that a person having ordinary knowledge in the technical field of the present invention can come up with various modifications within the scope of the technical idea described in the claims, and these modifications Of course, also belongs to the technical scope of the present invention.

For example, each of the above-described embodiments has described an example in which the pressure sensor 2 according to the present invention is applied to a differential pressure sensor. However, the present invention is not bound by such limitations. The pressure sensor 2 according to the present invention can also be applied to an absolute pressure sensor. When the present invention is applied to an absolute pressure sensor, although not shown, one of the low pressure side pressure guiding pipe 25 and the high pressure side pressure guiding pipe 26 is connected via a pressure guiding path in the housing 14. Connect to a vacuum or atmospheric air chamber. The inside of the passage from the air chamber to the pressure sensor 2 via one of the above pipes is filled with vacuum or air. The other pipe is configured such that the pressure of the fluid to be measured is transmitted through the pressure transfer medium 13 and the barrier diaphragm.

1 ... differential pressure transmitter, 2 ... pressure sensor, 13 ... pressure transmission medium, 14 ... housing, 15 ... sensor element, 18 ... closed space, 23 ... low pressure side pressure guiding path, 24 ... high pressure side pressure guiding path, 25 ... Low pressure side pressure guiding pipe, 26 ... High pressure side pressure guiding pipe.

Claims (4)

A body having a closed space inside and a sensor element that obtains a signal corresponding to the detected pressure is arranged in the closed space.
A pressure guiding pipe that supports the sensor element and functions as a part of a pressure guiding path that transmits pressure to the sensor element.
With
A pressure sensor in which the closed space is in a vacuum state, a state filled with an inert gas, or a state filled with air. The pressure sensor according to claim 1, wherein the sensor element is arranged apart from the boundary of the closed space. The pressure sensor according to claim 1, wherein the sensor element is arranged so that a part of the sensor element is in contact with the boundary of the closed space. The pressure guiding pipe
A first pressure guiding pipe that functions as a part of the first pressure guiding path that transmits the first pressure,
A second pressure guiding pipe that functions as a part of the second pressure guiding path that transmits the second pressure,
Including
The pressure sensor according to any one of claims 1 to 3, wherein the sensor element obtains a signal corresponding to a differential pressure between the first pressure and the second pressure.

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