JP2013181951A - Differential pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make peel-off of a junction of a sensor chip hardly occur.SOLUTION: A differential pressure sensor 200 is provided with a sensor chip 3 joined onto a wall surface 1-1a of a partition wall 1-1 positioned on the side of a first space 1-2, so that one face 3-1a of a sensor diaphragm 3-1 faces a first pressure-receiving diaphragm 2-1 and so that a communication passage 3-3 linking to the other face 3-1b of the sensor diaphragm 3-1 communicates with a penetration passage 1-4 of the partition wall 1-1. In the differential pressure sensor 200, the sealing pressure of a first pressure transmitting medium 5-1 sealed in a first sealing chamber 6-1 is made higher than that of a second pressure transmitting medium 5-2 sealed in a second sealing chamber 6-2. Thus, damage due to a back pressure is reduced and peel-off of junctions 4-1, 4-2 is hard to occur.

Description

  The present invention relates to a sealed liquid sealing type differential pressure sensor in which a pressure transmission medium is sealed as a sealed liquid.

  Conventionally, there are various types of differential pressure sensors. Among them, there is a sealed liquid sealing type differential pressure sensor in which a pressure transmission medium is sealed as a sealed liquid (for example, see Patent Document 1). . In this sealed liquid-sealed differential pressure sensor, an incompressible fluid such as silicone oil is used as a pressure transmission medium. FIG. 3 shows a cross-sectional view of a main part of an example of a conventional sealed liquid sealing type differential pressure sensor.

  In FIG. 3, reference numeral 1 denotes a metal body, which has a first space 1-2 and a second space 1-3 partitioned by a partition wall 1-1 as internal spaces. The partition wall 1-1 is provided with a through passage 1-4 that communicates the first space 1-2 and the second space 1-3. A first metal diaphragm (first pressure receiving diaphragm) 2-1 is provided in the opening 1-2a of the first space 1-2, and the opening 1-3a of the second space 1-3 is provided in the opening 1-3a. Is provided with a second metal diaphragm (second pressure receiving diaphragm) 2-2.

  Reference numeral 3 denotes a sensor chip, which is composed of a sensor diaphragm 3-1 and a pedestal 3-2. The sensor diaphragm 3-1 is made of silicon or the like, and the pedestal 3-2 is made of silicon or glass. The center portion of the sensor diaphragm 3-1 is thin, and a recess 3-1c is formed on the other surface 3-1b with respect to the one surface 3-1a, and the other of which the recess 3-1c is formed. One end surface 3-2a of the pedestal 3-2 is joined to the surface 3-1c side. The pedestal 3-2 has a cylindrical shape, and the communication passage 3- connected to the other surface 3-1b of the sensor diaphragm 3-1 by the hollow portion 3-2c and the concave portion 3-1c of the sensor diaphragm 3-1. 3 is formed.

  The sensor chip 3 has a communication passage 3-3 that communicates with the other surface 3-1b of the sensor diaphragm 3-1, such that one surface 3-1a of the sensor diaphragm 3-1 faces the first pressure receiving diaphragm 2-1. It is joined to the wall surface 1-1a of the partition wall 1-1 located on the first space 1-2 side so as to communicate with the through passage 1-4 of the partition wall 1-1. That is, the other end surface 3-2b of the pedestal 3-2 is connected to the wall surface 1- 1 of the partition wall 1-1 so that the hollow portion 3-2c of the pedestal 3-2 communicates with the through passage 1-4 of the partition wall 1-1. It is made to join to 1a. Hereinafter, a joint portion between the pedestal 3-2 and the partition wall 1-1 is referred to as a first joint portion 4-1, and a joint portion between the pedestal 3-2 and the sensor diaphragm 3-1 is referred to as a second joint portion 4-2. To do.

  The body 1 is sealed with a first pressure transmission medium 5-1 using the first space 1-2 as the first enclosure chamber 6-1. In addition, the communication path 3-3 that communicates with the second space 1-3, the through passage 1-4 of the partition wall 1-1, and the other surface 3-1b of the sensor diaphragm 3-1 is defined as a second enclosure chamber 6-2. The second pressure transmission medium 5-2 is sealed. The sealing of the first pressure transmission medium 5-1 into the first enclosure chamber 6-1 and the sealing of the second pressure transmission medium 5-2 into the second enclosure chamber 6-2 are as follows. Both are performed under the same conditions (under atmospheric pressure), and the sealing pressures of the first pressure transmission medium 5-1 and the second pressure transmission medium 5-2 are equal.

  In this sealed liquid sealing type differential pressure sensor 100, the pressure P1 received by the first pressure receiving diaphragm 2-1 is one surface 3 of the sensor diaphragm 3-1 via the first pressure transmission medium 5-1. The pressure P2 received by the second pressure receiving diaphragm 2-2 is transmitted to the other surface 3-1b of the sensor diaphragm 3-1 via the second pressure transmitting medium 5-2. As a result, the sensor diaphragm 3-1 bends according to the pressure difference between the pressures P1 and P2, and a signal according to the pressure difference is output from the sensor diaphragm 3-1. The sensor diaphragm 3-1 is formed with a strain resistance gauge whose resistance value changes according to a pressure change as a configuration for outputting a signal according to the pressure difference.

  For example, when the first pressure receiving diaphragm 2-1 side that receives the pressure P1 is the high pressure side and the second pressure receiving diaphragm 2-2 side that receives the pressure P1 is the low pressure side, the differential pressure sensor 100 has a high pressure on the low pressure side. When pressure (back pressure) higher than the side is applied, it has a weak point that it is fragile.

  That is, in this differential pressure sensor 100, when a higher pressure is applied to the high pressure side than to the low pressure side, the first joint portion 4-1 of the sensor chip 3 (the joint between the base 3-2 and the partition wall 1-1). Part (high-pressure side / low-pressure side boundary part)) and the second joint part 4-2 (joint part (high-pressure side / low-pressure side boundary part) between the pedestal 3-2 and the sensor diaphragm 3-1) are pressed. Therefore, the pressure resistance is high, but when a pressure (reverse pressure) higher than the high pressure side is applied to the low pressure side, a force is applied in the direction in which the joints 4-1 and 4-2 of the sensor chip 3 are peeled off. Therefore, it becomes fragile.

  For this reason, normally, the first pressure receiving diaphragm 2-1 side that receives the pressure P1 is used as the high pressure side, and the second pressure receiving diaphragm 2-2 side that receives the pressure P2 is used as the low pressure side.

JP-A-1-241193 (Patent No. 2595749)

  However, in the differential pressure sensor 100 having such a structure, the height relationship between the pressure P1 and the pressure P2 can be reversed or the height relationship between the pressure P1 and the pressure P2 is not reversed. The 2-1 side may be erroneously selected as the low pressure side and the second pressure receiving diaphragm 2-2 side as the high pressure side. If only the high pressure side and the low pressure side are determined, peeling of the joint portion of the sensor chip may occur. The weakness of being easy to occur cannot be resolved.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a differential pressure sensor in which peeling of a joint portion of a sensor chip hardly occurs.

  In order to achieve such an object, the present invention provides a body having a first space and a second space partitioned by a partition wall having a through passage, and a first provided in an opening of the first space. Pressure sensing diaphragm, a second pressure sensing diaphragm provided in the opening of the second space, and a sensor diaphragm that outputs a signal corresponding to a pressure difference received on one surface and the other surface, and one of the sensor diaphragms The sensor is joined to the wall surface of the partition located on the first space side so that the surface of the diaphragm faces the first pressure receiving diaphragm and the communication path communicating with the other surface of the sensor diaphragm is communicated with the through-passage of the partition A chip, a first pressure transmission medium that is sealed in the first space and transmits the pressure received by the first pressure receiving diaphragm to one surface of the sensor diaphragm, and the second space and the partition wall A differential pressure sensor including a second pressure transmission medium that is sealed in a communication path that communicates with the passage and the other surface of the sensor diaphragm, and that transmits the pressure received by the second pressure receiving diaphragm to the other surface of the sensor diaphragm. The sealing pressure of the first pressure transmission medium is higher than the sealing pressure of the second pressure transmission medium.

  According to this invention, since the sealing pressure of the first pressure transmission medium is higher than the sealing pressure of the second pressure transmission medium, the sealing pressure of the first pressure transmission medium and the second pressure The pressure difference from the sealing pressure of the transmission medium always acts in the direction of pressing the joint portion of the sensor chip. That is, in the conventional differential pressure sensor, the sealing pressure of the first pressure transmission medium and the sealing pressure of the second pressure transmission medium are the same. The joint is received as it is. In contrast, in the present invention, since the sealing pressure of the first pressure transmission medium is higher than the sealing pressure of the second pressure transmission medium, the first pressure transmission medium is sealed. The differential pressure between the pressure and the sealing pressure of the second pressure transmission medium acts in the direction of reducing the reverse pressure. Thereby, the damage of a back pressure is reduced and it becomes difficult to produce peeling of the junction part of a sensor chip.

  In the present invention, the pressure difference (sealing pressure difference) between the sealing pressure of the first pressure transmission medium and the sealing pressure of the second pressure transmission medium is the maximum differential pressure that may be applied as a reverse pressure. It may be determined in relation to the bonding force of the bonding portion of the sensor chip. That is, when the maximum differential pressure is applied as a reverse pressure, the first pressure transmission medium and the second pressure transmission medium are sealed with a pressure difference that can withstand the bonding force of the bonding portion of the sensor chip. It is good to do.

  In the present invention, the sensor chip only needs to include a sensor diaphragm, and may not necessarily have a configuration including a sensor diaphragm and a pedestal. When the sensor chip is configured to include a sensor diaphragm and a pedestal, the joint portion of the sensor chip includes a joint portion between one end surface of the pedestal and the other surface side of the sensor diaphragm, the other end surface of the pedestal, and a partition wall. There are two places at the joint with the wall. When the sensor chip is configured only by the sensor diaphragm, the joint portion of the sensor chip is one place of the joint portion between the wall surface of the partition wall and the other surface side of the sensor diaphragm.

  According to the present invention, since the sealing pressure of the first pressure transmission medium is higher than the sealing pressure of the second pressure transmission medium, the sealing pressure of the first pressure transmission medium and the second pressure transmission medium The pressure difference with the sealing pressure of the pressure transmission medium always acts in the direction in which the sensor chip joint is pressed, reducing the damage caused by the reverse pressure and making it difficult for the sensor chip joint to peel off.

It is sectional drawing which shows the principal part of one Embodiment (Embodiment 1) of the differential pressure sensor which concerns on this invention. It is sectional drawing which shows the principal part of other embodiment (Embodiment 2) of the differential pressure sensor which concerns on this invention. It is sectional drawing which shows the principal part of an example of the conventional sealing liquid sealing type differential pressure sensor.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view showing the main part of an embodiment (Embodiment 1) of a differential pressure sensor according to the present invention. 3, the same reference numerals as those in FIG. 3 denote the same or equivalent components as those described with reference to FIG. 3, and the description thereof will be omitted.

  In the differential pressure sensor of the first embodiment, the sealing pressure of the first pressure transmission medium 5-1 sealed in the first sealing chamber 6-1 is sealed in the second sealing chamber 6-2. The sealing pressure of the stopped second pressure transmission medium 5-2 is set higher. A differential pressure sensor in which the sealing pressure of the first pressure transmission medium 5-1 is higher than the sealing pressure of the second pressure transmission medium 5-2 is distinguished from the differential pressure sensor 100 shown in FIG. For this reason, reference numeral 200 indicates.

  In the differential pressure sensor 200, the sealing pressure of the first pressure transmission medium 5-1 is higher than the sealing pressure of the second pressure transmission medium 5-2. The differential pressure between the sealing pressure of 1 and the sealing pressure of the second pressure transmission medium 5-2 always acts in the direction in which the joint portions 4-1 and 4-2 of the sensor chip 3 are pressed.

  That is, in the conventional differential pressure sensor 100, when the sealing pressure of the first pressure transmission medium 5-1 and the sealing pressure of the second pressure transmission medium 5-2 are the same, a reverse pressure is applied. The joints 4-1 and 4-2 of the sensor chip 3 receive the pressure as it is.

  In contrast, in the differential pressure sensor 200, the sealing pressure of the first pressure transmission medium 5-1 is higher than the sealing pressure of the second pressure transmission medium 5-2. The differential pressure between the sealing pressure of the first pressure transmission medium 5-1 and the sealing pressure of the second pressure transmission medium 5-2 acts in the direction of reducing the reverse pressure. Thereby, the damage of a reverse pressure is reduced and peeling of the joining parts 4-1 and 4-2 of the sensor chip 3 is difficult to occur.

  In this differential pressure sensor 200, the pressure difference (sealing pressure difference) between the sealing pressure of the first pressure transmission medium 5-1 and the sealing pressure of the second pressure transmission medium 5-2 is opposite. It is determined by the relationship between the maximum differential pressure that can be applied as a pressure and the bonding force of the bonding portions 4-1 and 4-2 of the sensor chip 3. That is, when the maximum differential pressure is applied as a reverse pressure, the pressure difference is such that the bonding force of the bonding portions 4-1 and 4-2 of the sensor chip 3 can withstand the first pressure transmission medium 5-1. The second pressure transmission medium 5-2 is sealed.

  Further, in this differential pressure sensor 200, the sensor chip 3 is composed of the sensor diaphragm 3-1 and the pedestal 3-2, but the pedestal 3-2 is omitted and the sensor diaphragm 3 is omitted as shown in FIG. -1 may be the sensor chip 3 and may be configured to be bonded to the wall surface 1-1a of the partition wall 1-1 (second embodiment). In the differential pressure sensor 300, the concave portion 3-1c of the sensor diaphragm 3-1 serves as a communication path 3-3 that communicates with the other surface 3-1b of the sensor diaphragm 3-1. Further, the sensor chip 3 has only one joint portion of the joint portion 4-1 between the other surface 3-1b side of the diaphragm 3-1 and the wall surface 1-1a of the partition wall 1-1.

  Further, in this differential pressure sensor 200, the sensor diaphragm 3-1 is of a type in which a strain resistance gauge whose resistance value changes according to a pressure change is formed, but may be a capacitance type sensor chip. A capacitance type sensor chip includes a substrate having a predetermined space (capacitance chamber), a diaphragm disposed in the space of the substrate, a fixed electrode formed on the substrate, and a movable electrode formed on the diaphragm. And. When the diaphragm is deformed by receiving pressure, the distance between the movable electrode and the fixed electrode changes, and the capacitance between them changes.

[Extension of the embodiment]
The present invention has been described above with reference to the embodiment. However, the present invention is not limited to the above embodiment. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the technical idea of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Body, 1-1 ... Partition, 1-1a ... Wall surface, 1-2 ... 1st space, 1-3 ... 2nd space, 1-4 ... Through-passage, 2-1 ... 1st pressure receiving diaphragm 2-2 ... second pressure receiving diaphragm, 3 ... sensor chip, 3-1 ... sensor diaphragm, 3-1a ... one surface, 3-1b ... other surface, 3-1c ... concave, 2-2 ... pedestal 3-3 ... Communication path, 4-1 ... first joint, 4-2 ... second joint, 5-1 ... first pressure transmission medium, 5-2 ... second pressure transmission Medium, 6-1 ... first enclosure chamber, 6-2 ... second enclosure chamber, 200,300 ... differential pressure sensor.

Claims (2)

A body having a first space and a second space partitioned by a partition wall having a through path;
A first pressure receiving diaphragm provided in an opening of the first space;
A second pressure receiving diaphragm provided in the opening of the second space;
A sensor diaphragm for outputting a signal corresponding to a pressure difference received on one surface and the other surface is provided, and one surface of the sensor diaphragm faces the first pressure receiving diaphragm and communicates with the other surface of the sensor diaphragm. A sensor chip joined to the wall surface of the partition wall located on the first space side so as to communicate the communication path with the through-passage of the partition wall;
A first pressure transmission medium sealed in the first space and transmitting the pressure received by the first pressure receiving diaphragm to one surface of the sensor diaphragm;
The second space, a through-passage of the partition wall, and a communication path that communicates with the other surface of the sensor diaphragm are sealed, and a pressure received by the second pressure receiving diaphragm is transmitted to the other surface of the sensor diaphragm. Two pressure transmission media,
The differential pressure sensor, wherein a sealing pressure of the first pressure transmission medium is higher than a sealing pressure of the second pressure transmission medium. The differential pressure sensor according to claim 1,
The sensor chip is
The sensor diaphragm and a cylindrical pedestal,
One end surface of the pedestal is joined to the other surface side of the sensor diaphragm,
The differential pressure sensor, wherein the other end surface of the pedestal is joined to the wall surface of the partition wall.

Images