JP2019056666A - Pressure change measuring device - Google Patents

Abstract

To provide a pressure change measuring device which enables a precise measurement by stabilizing the pressure and/or temperature in a pressure chamber as a basis for differential pressure measurement.SOLUTION: A pressure change measuring device (1) comprises: a circuit board (3) having an opening (4); a sensor (5) having a first pressure passage hole (8), which is disposed so as to cover the opening of the circuit board; a first cavity (6) disposed at the sensor side of the circuit board, which is composed so as to form a first pressure chamber enclosing the sensor; a second cavity (7) having a second pressure passage hole (9), which is dispose at the opposite side of the sensor on the circuit board and is composed so as to form a second pressure chamber covering the opening.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pressure change measuring device.

  Conventionally, as a device for measuring a change in pressure of a measurement target, a pressure chamber (inner chamber), a differential pressure sensor (diaphragm, etc.) for detecting a differential pressure between the pressure in the pressure chamber and the pressure of the measurement target, and the measurement target A pressure change measuring device having a pressure passage hole through which a pressure transmission medium can flow into and out of a pressure chamber is known (for example, Patent Document 1).

  FIG. 5 is a block diagram showing a pressure change measuring device 51 according to the prior art. The pressure change measuring device 51 includes a circuit board 53 connected to the wiring 52, a sensor (diaphragm) 55 disposed so as to cover the opening 54 of the circuit board, and a pressure chamber disposed on the circuit board and surrounding the sensor. And a cavity 56 to be formed. The diaphragm 55 is provided with a pressure sensing gauge resistor, and a part of the diaphragm 55 is provided with a pressure passage hole 57.

  In such a pressure change measuring device, the pressure passage hole 57 has a very small structure, and restricts the flow of the pressure transmission medium to the inside of the pressure chamber surrounded by the cavity 56. Further, the pressure Pc in the pressure chamber varies depending on the inflow / outflow amount of the pressure transmission medium. For this reason, the pressure Pc in the pressure chamber follows the change in the pressure (= external pressure) Pa to be measured with a delay. Therefore, by measuring the pressure difference (Pa−Pc) between the pressure Pc in the pressure chamber and the pressure Pa of the measurement object, it is possible to detect a change in pressure of the measurement object.

JP-A-2-52229

  The above-described pressure change measuring device is a differential pressure sensor in which the diaphragm membrane is thinned to increase sensitivity. Therefore, when the outside air temperature Ta changes or when external light (visible light, infrared light, etc.) enters, heat is transmitted through the opening on the opening side of the circuit board or the board, and the pressure surrounded by the cavity The internal temperature Tc of the chamber changes. When the internal temperature Tc of the pressure chamber changes, the pressure Pc in the pressure chamber changes according to the gas equation of state (Pc × Vc / Tc = constant value). Since the differential pressure sensor measures the differential pressure with the external pressure Pa using the pressure Pc in the pressure chamber as a reference, a change in the outside air temperature Ta or light from the outside becomes disturbance (noise), and the reference pressure Pc is If it changes, a measurement error occurs. As described above, in the conventional pressure change measuring device, the pressure in the pressure chamber, which is a reference for the differential pressure measurement, easily changes due to the influence of the outside air temperature or incident light, and it is difficult to measure with high accuracy. was there.

  It is known that the measurement error due to this disturbance particularly depends on the change amount and change speed of the internal temperature Tc of the pressure chamber, and the error is smaller when the change amount is smaller and when the change speed is smaller. That is, it is necessary to keep the internal temperature Tc of the pressure chamber as stable as possible, and it is necessary to reduce the amount of change and the change rate of the internal temperature Tc of the pressure chamber with respect to a sudden change in the outside air temperature Ta. On the opening side of the circuit board, heat from the outside is easily transferred to the inside of the cavity through the opening, and the internal temperature Tc of the pressure chamber is likely to change.

  The present invention has been made in view of the above circumstances, and provides a pressure change measuring device capable of highly accurate measurement by stabilizing the pressure Pc and / or the temperature Tc in the pressure chamber, which is a reference for differential pressure measurement. The purpose is to provide.

  In order to solve the above-described problem, a pressure change measuring device according to one aspect of the present invention includes a circuit board having an opening, and is arranged to cover the opening of the circuit board, and has a first pressure passage hole. A sensor, a first cavity disposed on the sensor side of the circuit board and configured to form a first pressure chamber surrounding the sensor; and disposed on an opposite side of the circuit board to the sensor, the opening portion A second cavity configured to form a second pressure chamber to be covered and having a second pressure passage hole.

  The shape (capacitance) of the first cavity and the shape (capacitance) of the second cavity may be substantially equal, and the first cavity and the second cavity may be arranged symmetrically across the circuit board.

  The material of the first cavity and the material of the second cavity may be substantially equal, and the first cavity and the second cavity may be arranged symmetrically across the circuit board.

  The second cavity may be made of a material having a light shielding property and low thermal conductivity.

  A portion of the circuit board may be thin.

  The second pressure passage hole may be covered with a sound absorbing material or a humectant.

  Two or more second pressure passage holes may be provided.

  The second pressure passage hole may have a mesh shape provided on one surface of the second cavity.

  According to the pressure change measuring device and the pressure change measuring method according to each aspect of the present invention, it is possible to stabilize the pressure Pc and / or the temperature Tc in the pressure chamber which is a reference for differential pressure measurement. Thereby, it is possible to provide a pressure change measuring apparatus and a pressure change measuring method capable of measuring pressure changes with high accuracy.

It is a lineblock diagram showing the pressure change measuring device concerning a 1st embodiment of the present invention. It is a block diagram which shows the pressure change measuring apparatus which concerns on 2nd Embodiment of this invention. It is a block diagram which shows the pressure change measuring apparatus which concerns on 3rd Embodiment of this invention. It is a block diagram which shows the pressure change measuring apparatus which concerns on 4th Embodiment of this invention. It is a block diagram which shows the pressure change measuring apparatus which concerns on a prior art.

  Hereinafter, a pressure change measuring device according to an embodiment of the present invention will be described in detail with reference to the drawings.

(First embodiment)
First, the configuration of the pressure change measuring device according to the first embodiment of the present invention will be described. FIG. 1 is a configuration diagram showing a pressure change measuring apparatus 1 according to the first embodiment of the present invention. The pressure change measuring device 1 includes a circuit board 3 connected to the wiring 2, a sensor 5 arranged so as to cover the opening 4 of the circuit board, and a first pressure chamber arranged on the sensor side of the circuit board and surrounding the sensor. And a second cavity 7 that is disposed on the opposite side (opening side) of the circuit board from the sensor and forms a second pressure chamber that covers the opening 4 of the circuit board.

  The sensor 5 detects a differential pressure (Pa−Pc) between the pressure Pc inside the first pressure chamber surrounded by the first cavity 6 and the external pressure (= pressure Pa to be measured). The sensor 5 may include, for example, a cantilever configured to be deformed according to a differential pressure between the internal pressure of the first pressure chamber and the external pressure. A first pressure passage hole 8 is provided in a part of the sensor 5, and the pressure transmission medium passes through the first pressure passage hole 8 to the inside of the first pressure chamber surrounded by the first cavity 6 and the second pressure passage medium. It is possible to flow into and out of the second pressure chamber surrounded by the cavity 7. The first pressure passage hole 8 has a very small structure and restricts the flow of the pressure transmission medium into the first pressure chamber surrounded by the first cavity 6.

  A second pressure passage hole 9 is provided in a part of the second cavity 7, and the pressure transmission medium flows between the inside and the outside of the second pressure chamber through the second pressure passage hole 9. it can. Here, the size (area) of the second pressure passage hole 9 is preferably equal to or larger than the size (area) of the first pressure passage hole 8. With such a configuration, the pressure Pa2 inside the second pressure chamber is substantially the same as the external pressure Pa (Pa2≈Pa).

  That is, the pressure transmission medium flows in and out between the outside and the inside of the second pressure chamber through the second pressure passage hole 9, and further, the inside of the second pressure chamber and the first portion through the first pressure passage hole 8. It flows in and out between the inside of the pressure chamber. The pressure Pc inside the first pressure chamber varies depending on the inflow / outflow amount of the pressure transmission medium. The pressure Pc in the pressure chamber follows the change in the pressure (= external pressure) Pa to be measured with a delay. Therefore, by measuring the pressure difference (Pa−Pc) between the pressure Pc in the pressure chamber and the pressure Pa of the measurement object, it is possible to detect a change in pressure of the measurement object.

  Thus, the pressure change measuring apparatus according to the first embodiment of the present invention is characterized in that a cavity (second cavity 7) is also provided on the side (opening side) opposite to the sensor of the circuit board. By providing the second cavity 7, heat transfer from the outside of the opening side of the circuit board to the inside of the first pressure chamber is insulated via the opening 4 and the circuit board 3, and the opening side of the circuit board The light (visible light, infrared rays, etc.) from the outside to the inside of the first pressure chamber can be shielded. Therefore, the temperature Tc inside the first pressure chamber is stabilized.

  Further, since the second pressure passage hole 9 is provided in a part of the second cavity 7, the pressure Pa2 inside the second pressure chamber surrounded by the second cavity 7 is substantially the same as the external pressure Pa. It has become. Thereby, highly accurate pressure change measurement is enabled.

  Note that the shape of the first cavity 6 and the shape of the second cavity 7 may be the same or different. Further, the capacity of the first pressure chamber surrounded by the first cavity 6 and the capacity of the second pressure chamber surrounded by the second cavity 7 may be the same or different. The material of the first cavity 6 and the material of the second cavity 7 may be the same or different.

  When the shape and material of the first cavity 6 and the second cavity 7 are substantially the same, the first cavity 6 and the second cavity 7 are arranged symmetrically with the circuit board 3 in between, whereby the inside of the first pressure chamber And the temperature Ta2 inside the second pressure chamber can be made substantially equal (Tc≈Ta2). That is, even if the external temperature Ta changes, the temperature environment around the sensor 5 can be made uniform.

  The 1st cavity 6 and / or the 2nd cavity 7 may be comprised from the material which has light-shielding property with respect to visible light, near infrared rays, far infrared rays, etc. The 1st cavity 6 and / or the 2nd cavity 7 may be comprised from materials, such as a plastic with low heat conductivity. With such a configuration, heat from the outside to the inside of the pressure chamber can be further blocked, and the temperature environment around the sensor 5 can be made uniform.

  The first cavity 6 and / or the second cavity 7 may have a material / structure for insulating sound. With such a configuration, disturbance (sound noise) from the outside to the inside of the pressure chamber can be reduced, and the environment around the sensor 5 can be further stabilized.

(Second Embodiment)
Next, the configuration of the pressure change measuring device according to the second embodiment of the present invention will be described. FIG. 2 is a configuration diagram showing a pressure change measuring device 21 according to the second embodiment of the present invention. The difference from the pressure change measuring device 1 according to the first embodiment shown in FIG. 1 is that the pressure change measuring device 21 according to the second embodiment is provided with grooves 10 and 11 in a part of the substrate. Other configurations are the same as those of the pressure change measuring apparatus 1 according to the first embodiment shown in FIG.

  In the example shown in FIG. 2, grooves 10 and 11 are provided on the sensor side surface of the substrate 3 outside the first cavity 6 and the second cavity 7. By providing the grooves 10 and 11 in a part of the substrate 3 in this way, the thermal resistance of this part can be increased, and the heat conduction transmitted from the outside to the pressure chamber through the substrate can be suppressed. That is, with such a configuration, in the pressure change measuring device 21 according to the second embodiment, heat from the outside to the inside of the pressure chamber can be further blocked, and the temperature environment around the sensor 5 can be made uniform. it can.

  The position of the groove may not be on the sensor side surface of the substrate 3, but may be inside the first cavity 6 and the second cavity 7. Further, the number of grooves is not limited to two. Further, it is not necessary to provide a groove on the substrate, and the same effect can be obtained if a part of the substrate is thin. Here, a flexible substrate may be used as the substrate 3.

(Third embodiment)
Next, the configuration of the pressure change measuring device according to the third embodiment of the present invention will be described. FIG. 3A is a configuration diagram showing a pressure change measuring device 31 according to the third embodiment of the present invention, and FIG. 3B shows a pressure change measuring device 32 according to the third embodiment of the present invention. FIG. The difference from the pressure change measuring device 1 according to the first embodiment shown in FIG. 1 is that in the pressure change measuring devices 31 and 32 according to the third embodiment, a sound absorbing material and / or so as to cover the second pressure passage hole 9 is used. The heat insulating material 12 is provided. Other configurations are the same as those of the pressure change measuring apparatus 1 according to the first embodiment shown in FIG.

  In the pressure change measuring device 31 shown in FIG. 3A, the sound absorbing material and / or the heat insulating material 12 covers the second pressure passage hole 9 outside the second cavity 7. Further, in the pressure change measuring device 32 shown in FIG. 3B, the sound absorbing material and / or the heat insulating material 12 covers the second pressure passage hole 9 inside the second cavity 7. Here, the sound absorbing material and / or the heat insulating material 12 is a material having air permeability.

  With such a configuration, in the pressure change measurement devices 31 and 32 according to the third embodiment, heat conduction between the outside and the second pressure chamber through the second pressure passage hole 9 (heat dissipation and heat transfer). Can be reduced. In addition, noise noise transmitted from the outside to the second pressure chamber through the second pressure passage hole 9 can be reduced. In this way, the environment around the sensor 5 can be further stabilized.

(Fourth embodiment)
Next, the configuration of the pressure change measuring device according to the fourth embodiment of the present invention will be described. FIG. 4A is a configuration diagram showing a pressure change measuring device 41 according to the fourth embodiment of the present invention, and FIG. 4B shows a pressure change measuring device 42 according to the fourth embodiment of the present invention. FIG. The difference from the pressure change measurement device 1 according to the first embodiment shown in FIG. 1 is that the pressure change measurement devices 41 and 42 according to the fourth embodiment differ in the form of the second pressure passage hole 9. Other configurations are the same as those of the pressure change measuring apparatus 1 according to the first embodiment shown in FIG.

  In the pressure change measuring device 41 shown in FIG. 4A, a second pressure passage hole 9 a is provided on the left side of the second cavity 7, and a second pressure passage hole 9 b is provided on the right side of the second cavity 7. As described above, by providing the second pressure passage holes 9a and 9b on the left and right sides of the second cavity 7, even if there is a pressure difference between the outside on the left side and the outside on the right side of the second cavity 7, The internal pressure Pa2 can be made substantially close to the external pressure Pa (Pa2≈Pa).

  In the pressure change measuring device 42 shown in FIG. 4B, a mesh-like second pressure passage hole 9 c is provided on the lower surface of the second cavity 7. With such a configuration, the pressure Pa2 inside the second pressure chamber can be made substantially close to the external pressure Pa (Pa2≈Pa).

  With such a configuration, in the pressure change measuring devices 41 and 42 according to the fourth embodiment, the pressure Pa2 inside the second pressure chamber surrounded by the second cavity 7 can be made substantially close to the external pressure Pa. Therefore, it is possible to measure the pressure change with higher accuracy.

  In the present specification, words indicating directions such as “front, back, top, bottom, right, left, vertical, horizontal, vertical, horizontal, row and column” are used to describe these directions in the apparatus of the present invention. I use it. Accordingly, these terms used to describe the specification of the present invention should be interpreted relatively in the device of the present invention.

  As used herein, terms such as “roughly”, “about”, “substantially” and the like mean that there is a reasonable range of variation within a range where the final result does not change significantly. Therefore, the term “substantially equal” includes the case of “perfectly equal”.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment and its modification. Additions, omissions, substitutions, and other modifications can be made without departing from the spirit of the present invention. Further, the present invention is not limited by the above description, and is limited only by the scope of the appended claims.

1, 21, 31, 32, 41, 42, 51 Pressure change measuring device 2, 52 Wiring 3, 53 Circuit board 4, 54 Opening 5 Sensor (cantilever)
6 First cavity 7 Second cavity
8 First pressure passage hole 9, 9a, 9b, 9c Second pressure passage hole 10, 11 Groove 12 Sound absorbing material / humectant 55 Sensor 56 Cavity 57 Pressure passage hole

Claims (8)

A circuit board having an opening;
A sensor disposed to cover the opening of the circuit board and having a first pressure passage hole;
A first cavity disposed on the sensor side of the circuit board and configured to form a first pressure chamber surrounding the sensor;
A second cavity disposed on the opposite side of the circuit board from the sensor and configured to form a second pressure chamber covering the opening, and having a second pressure passage hole;
A pressure change measuring device comprising: The shape (capacitance) of the first cavity and the shape (capacitance) of the second cavity are substantially equal, and the first cavity and the second cavity are arranged symmetrically across the circuit board. The pressure change measuring apparatus according to claim 1. The material of the first cavity and the material of the second cavity are substantially equal, and the first cavity and the second cavity are arranged symmetrically with the circuit board interposed therebetween. 2. The pressure change measuring apparatus according to 2. The pressure change measuring device according to any one of claims 1 to 3, wherein the second cavity is made of a material having light shielding properties and low thermal conductivity. The pressure change measuring device according to any one of claims 1 to 4, wherein a part of the circuit board is thin. The pressure change measuring device according to any one of claims 1 to 5, wherein the second pressure passage hole is covered with a sound absorbing material or a humectant. The pressure change measuring apparatus according to any one of claims 1 to 6, wherein two or more second pressure passage holes are provided. The pressure change measuring device according to any one of claims 1 to 6, wherein the second pressure passage hole has a mesh shape provided on one surface of the second cavity.

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