Differential pressure sensor

Abstract

To prevent the formation of a region in which pressure transmission material is not introduced.SOLUTION: A communication passage formed of a first passage 106a, a second passage 106b, and a connection path 106c, and an introduction path 108 are nonlinear. For example, the connection path 106c as a component of the communication passage is nonlinear. For example, the connection path 106c may meander in a zigzag manner. For example, the connection path 106c meanders in a plane parallel to a surface of a diaphragm layer 101.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a differential pressure sensor. [Background technology]

[0002] A known industrial differential pressure sensor is a diaphragm parallel arrangement type differential pressure sensor that uses a sensor chip with a structure in which two diaphragms are arranged side by side in a planar direction, and two chambers (diaphragm chambers) formed directly above each diaphragm are spatially connected to each other by a connecting path (see Patent Document 1). In this type of differential pressure sensor, the two diaphragm chambers and the connecting path are filled with a pressure transmitting material such as oil in order to transmit the pressure applied to one diaphragm to the other diaphragm.

[0003] To introduce oil into the diaphragm chamber and connecting passage as described above, oil is applied to the oil inlet of the oil inlet passage that connects to the connecting passage, and the entire sensor chip is evacuated, allowing oil to be introduced from the oil inlet passage into the connecting passage and the two diaphragm chambers and sealed therein. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-159597 Summary of the Invention [Problem to be solved by the invention]

[0005] However, near the edge of the end of the diaphragm chamber, the gap can become very small due to vacuuming, creating an area where oil cannot be introduced. If the gap is small, the piping resistance increases, preventing air bubbles from escaping and preventing oil from entering. If the area where oil has been introduced is sealed in this state, there is a concern that air bubbles will get into the sealed area (oil-filled space), preventing pressure from being transmitted correctly.

[0006] The present invention has been made to solve the above problems, and has an object to prevent the formation of a region where no pressure transmitting material is introduced. [Means for solving the problem]

[0007] The differential pressure sensor according to the present invention comprises displaceable diaphragms provided at two locations on the diaphragm layer and receiving the pressure of the fluid to be measured; a strain measuring unit provided near the peripheral edge of each diaphragm and measuring the distortion of the diaphragm; a first component bonded to one surface of the diaphragm layer; a second component bonded to the other surface of the diaphragm layer; two diaphragm chambers formed in the first component on the side where the diaphragm displaces when pressure is applied to each diaphragm; a communication passage formed in the first component and connecting the two diaphragm chambers; an introduction passage connecting the communication passage to the outside of the first component; and two pressure introduction passages formed in the second component and introducing the pressure of the fluid to each of the diaphragms provided at two locations, wherein the communication passage or introduction passage is non-linear, or the pipe diameter of at least a portion of the communication passage or introduction passage is smaller than the surrounding area.

[0008] In one configuration example of the above differential pressure sensor, the communication passage includes two passages connected to the two diaphragm chambers, respectively, and a connecting passage extending in a direction parallel to the surface of the diaphragm layer connecting the two passages, and the introduction passage is connected to the connecting passage, which is non-linear.

[0009] In one configuration example of the differential pressure sensor, the connection path is serpentine.

[0010] In one configuration example of the differential pressure sensor, the connection path meanders in a plane parallel to the surface of the diaphragm layer.

[0011] In one configuration example of the differential pressure sensor, the two diaphragm chambers are configured from concave surfaces formed in the first component. [Effects of the Invention]

[0012] As described above, according to the present invention, the communication passage or introduction passage is non-linear, so that it is possible to prevent the formation of an area into which the pressure transmitting material is not introduced. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1(a) is a cross-sectional view showing the configuration of a differential pressure sensor according to an embodiment of the present invention, and FIG. 1(b) is a plan view showing a partial configuration. [Figure 2] FIG. 2 is a plan view showing a partial configuration of another differential pressure sensor according to an embodiment of the present invention. [Figure 3] FIG. 3(a) is a cross-sectional view showing the configuration of another differential pressure sensor according to an embodiment of the present invention, and FIG. 3(b) is a plan view showing a partial configuration. [Figure 4] FIG. 4 is a plan view showing a partial configuration of another differential pressure sensor according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] A differential pressure sensor according to an embodiment of the present invention will now be described with reference to Figure 1. This differential pressure sensor includes a first diaphragm 101a, a second diaphragm 101b, a first component 103, a second component 104, a first diaphragm chamber 105a, a second diaphragm chamber 105b, a first passage 106a, a second passage 106b, a connection passage 106c, an introduction passage 108, a first pressure introduction passage 109a, and a second pressure introduction passage 109b.

[0015] The first diaphragm 101a and the second diaphragm 101b are provided at two locations on the diaphragm layer 101. Each of the first diaphragm 101a and the second diaphragm 101b is displaceable and receives the pressure of the fluid to be measured. A strain measuring unit 102 that measures the strain of the first diaphragm 101a and the second diaphragm 101b is provided near the peripheral edge of each of the first diaphragm 101a and the second diaphragm 101b.

[0016] Each diaphragm has strain measuring units 102 at multiple locations. The strain measuring units 102 can be composed of, for example, piezo-resistive elements. The piezo-resistive elements formed at multiple locations form a bridge circuit. When stress is generated in each diaphragm while a constant current is flowing, this bridge circuit functions as a differential pressure detection unit that outputs a change in the resistance value of each piezo-resistive element due to the generated stress as a change in voltage. Each node of this bridge circuit is connected to an electrode (not shown) via a wiring pattern formed on the surface of the diaphragm layer 101 in an area (not shown).

[0017] First passage 106a is connected to first diaphragm chamber 105a, and second passage 106b is connected to second diaphragm chamber 105b. First passage 106a and second passage 106b are connected by connection path 106c that extends in a direction parallel to the surface of diaphragm layer 101. First passage 106a, second passage 106b, and connection path 106c are formed in first component 103. First passage 106a, second passage 106b, and connection path 106c form a communication path that connects first diaphragm chamber 105a and second diaphragm chamber 105b.

[0018] The first component 103 is bonded to one surface of the diaphragm layer 101. The first component 103 may be composed of, for example, a first substrate 106 and a second substrate 107. In each of the first diaphragm 101a and the second diaphragm 101b, two chambers, a first diaphragm chamber 105a and a second diaphragm chamber 105b, are formed in the first component 103 (first substrate 106) on the side where the first diaphragm 101a and the second diaphragm 101b are displaced when pressure is applied. The first diaphragm 101a and the second diaphragm chamber 105b may be formed from a concave surface formed in the first component 103. The first substrate 106 and the second substrate 107 may be made of, for example, single crystal silicon.

[0019] Furthermore, first passage 106a and second passage 106b are formed to penetrate first substrate 106 in the thickness direction. Furthermore, connection passage 106c can be formed by a groove formed in the bonding surface of first substrate 106 to second substrate 107. Furthermore, introduction passage 108 is formed to penetrate second substrate 107 in the thickness direction. Introduction passage 108 connects the communicating passage to the outside of first component 103. Furthermore, a recess 111 is formed in the surface of second substrate 107, and introduction passage 108 is connected to recess 111. After the two first diaphragm chambers 105a, second diaphragm chamber 105b, the communicating passage, and introduction passage 108 are filled with a pressure transmission material such as silicone oil, recess 111 is sealed with sealing member 112. When the differential pressure sensor according to the embodiment is completed, the two diaphragm chambers, first diaphragm chamber 105a, second diaphragm chamber 105b, communication passage, and introduction passage 108 are filled with a pressure transmission material.

[0020] The second component 104 is bonded to the other surface of the diaphragm layer 101. Two pressure introduction paths, a first pressure introduction path 109a and a second pressure introduction path 109b, are formed in the second component 104. The second component 104 is also bonded onto a base 110 made of glass or the like. The base 110 is formed with a first through-hole 110a connected to the first pressure introduction path 109a and a second through-hole 110b connected to the second pressure introduction path 109b. The first through-hole 110a and the first pressure introduction path 109a introduce the pressure of the fluid to be measured into the first diaphragm chamber 105a. The second through-hole 110b and the second pressure introduction path 109b introduce the pressure of the fluid to be measured into the second diaphragm chamber 105b.

[0021] Furthermore, in the differential pressure sensor according to the embodiment, at least one of the communication path and the introduction path 108 is non-linear. For example, the connection path 106c constituting the communication path is non-linear. For example, the connection path 106c may be zigzag-shaped as shown in FIG. 1(b). Alternatively, the connection path 106c may be curved-shaped as shown in FIG. 2. For example, the connection path 106c is curved in a plane parallel to the surface of the diaphragm layer 101.

[0022] As described above, by making the communication hole non-linear and increasing the piping length, the vacuum conductance can be reduced compared to when the communication hole is linear. With this configuration, the vacuum conductance of the communication hole can be made even smaller than the vacuum conductance of the pressure introduction path.

[0023] Furthermore, by making the diameter of at least one portion of the communication passage or the introduction passage 108 smaller than the surrounding area, the vacuum conductance can be reduced. With this configuration, the vacuum conductance of the communication hole can be made even smaller than the vacuum conductance of the pressure introduction passage. For example, as shown in FIG. 3, the diameter of at least one portion of the introduction passage 108a can be made smaller than the surrounding area. In this case, the connection passage 106'c can be linear. Note that, even in this case, the connection passage 106'c can be non-linear. Furthermore, as shown in FIG. 4, the diameter of at least one portion of the connection passage 106d can be made smaller than the surrounding area. The other configurations are the same as those of the differential pressure sensor described using FIG. 1.

[0024] By creating a vacuum difference by making the pressure introduction path high conductance and the communication hole low conductance, a transitional period is created in which the diaphragm chamber side is in a lower vacuum state than the pressure introduction path side during evacuation when introducing the pressure transmission material. During this period, the diaphragm bends toward the pressure introduction path, widening the gap near the edge of the terminal end of the diaphragm chamber, allowing the pressure transmission material to penetrate into this region. After this, when the diaphragm chamber side also reaches a high vacuum state, the diaphragm becomes flat, allowing the pressure transmission material to be sealed in without any air bubbles being trapped near the edge. Thus, according to this embodiment, air bubbles are easily removed during evacuation when introducing the pressure transmission material, preventing the formation of a region where the pressure transmission material is not introduced.

[0025] As described above, according to the embodiment of the present invention, since the communication passage or introduction passage is non-linear, it is possible to prevent the formation of an area where the pressure transmitting material is not introduced.

[0026] It should be noted that the present invention is not limited to the embodiments described above, and it is clear that many modifications and combinations can be made by a person having ordinary knowledge in the art within the technical concept of the present invention. [Explanation of symbols]

[0027] 101...diaphragm layer, 101a...first diaphragm, 101b...second diaphragm, 102...strain measuring section, 103...first component, 104...second component, 105a...first diaphragm chamber, 105b...second diaphragm chamber, 106...first substrate, 106a...first passage, 106b...second passage, 106c...connection path, 107...second substrate, 108...introduction path, 109a...first pressure introduction path, 109b...second pressure introduction path, 110...base, 110a...first through hole, 110b...base, 111...recess, 112...sealing member.

Claims

1. a diaphragm provided at two locations on the diaphragm layer, the diaphragm being displaceable and receiving the pressure of the fluid to be measured; a strain measuring unit provided near a peripheral end of each of the diaphragms and configured to measure the strain of the diaphragm; a first component bonded to one surface of the diaphragm layer; a second component bonded to the other surface of the diaphragm layer; In each of the diaphragms, two diaphragm chambers are formed in the first part on the side where the diaphragm is displaced when pressure is applied; a communication passage formed in the first component and communicating the two diaphragm chambers; an introduction path connecting the communication path and the outside of the first component; two pressure introduction paths for introducing the pressure of the fluid to be measured to each of the diaphragms formed in the second component and provided at two locations; Equipped with The communication passage or the introduction passage is non-linear, or at least a part of the communication passage or the introduction passage has a smaller pipe diameter than the surrounding area.

2. 2. The differential pressure sensor according to claim 1, the communication passage includes two passages that are connected to the two diaphragm chambers, respectively, and a connecting path that connects the two passages and extends in a direction parallel to the surface of the diaphragm layer, the introduction path is connected to the connection path, A differential pressure sensor in which the connecting path is non-linear.

3. 3. The differential pressure sensor according to claim 2, The connecting path is a serpentine differential pressure sensor.

4. 4. The differential pressure sensor according to claim 3, The connecting path is a serpentine path in a plane parallel to the surface of the diaphragm layer.

5. The differential pressure sensor according to any one of claims 1 to 4, The two diaphragm chambers are formed from concave surfaces formed in the first component.

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