JP7422249B2 - flow rate detection device - Google Patents

Description

The present disclosure relates to a flow rate detection device.

BACKGROUND ART Inventions related to detection devices such as humidity detection devices have been known from the past (see Patent Document 1 below). The detection device described in Patent Document 1 includes a semiconductor substrate, a detection section, an electrostatic discharge (ESD) protection circuit, and a dummy pattern (summary, etc.). The detection section is provided above the semiconductor substrate and outputs a signal according to a physical quantity. The ESD protection circuit includes a MOS transistor on the semiconductor substrate. The dummy pattern is formed on the semiconductor substrate using the same material as the gate electrode included in the ESD protection circuit.

In the detection device of Patent Document 1, the dummy pattern is formed in a region other than the humidity detection section, the temperature detection section, the heating section, the ESD protection circuit, and the pad, and is connected to the signal line connected to the humidity detection section and the temperature detection section. (paragraphs 0087 to 0088, FIG. 12, etc.). By providing a dummy pattern, the arrangement density, which is the ratio of the area of the gate electrode and dummy pattern to the area of the sensor chip, is approximately 10% or more, which stabilizes the development process, improves pattern processing accuracy, and improves yield. (paragraphs 0095 and 0097, FIG. 15).

In addition, in the detection device of Patent Document 1, since the ESD protection circuit is connected to the pad as the input terminal or output terminal of the sensor chip, the ESD protection circuit is applied to the sensor chip during manufacturing, etc., and enters the inside through the pad. Allows ESD surge to escape to ground. This suppresses electrostatic damage to internal circuits such as the humidity detection section, temperature detection section, and heating section. In particular, it is possible to prevent dielectric breakdown of the humidity sensitive film and modification of the material of the humidity sensitive film due to ESD surge being applied to the humidity sensitive film of the humidity detection unit (paragraph 0120).

Japanese Patent Application Publication No. 2020-085503

Unlike the above-mentioned conventional humidity detection device, the flow rate detection device has a problem in that charged dust contained in the gas is adsorbed by the detection section that detects the flow rate of the gas. The present disclosure provides a flow rate detection device that can suppress charged dust contained in gas from being adsorbed by a detection unit.

One aspect of the present disclosure includes a detection unit that detects the flow rate of gas, wiring connected to the detection unit, and a protective film that covers the detection unit and the wiring and is exposed to the gas flow path. The flow rate detection device further includes a charge removal wiring connected to ground and covered with the protective film, wherein the distance from the flow path to the charge removal wire is equal to the distance from the flow path to the wire. This is a flow rate detection device characterized by the following.

According to the above-described aspect of the present disclosure, it is possible to provide a flow rate detection device that can suppress charged dust contained in gas from being adsorbed by the detection section.

FIG. 1 is a system diagram showing an embodiment of a flow rate detection device according to the present disclosure. FIG. 2 is a schematic cross-sectional view of the physical quantity detection device shown in FIG. 1. FIG. 3 is a schematic plan view of the detection section shown in FIG. 2. FIG. 4 is a schematic cross-sectional view of the detection unit along line IV-IV in FIG. 3. FIG. 5 is a schematic cross-sectional view showing a first modification of the detection section shown in FIG. 4. FIG. FIG. 5 is a schematic cross-sectional view showing a second modification of the detection section shown in FIG. 4. FIG.

Hereinafter, embodiments of a flow rate detection device according to the present disclosure will be described with reference to the drawings.

FIG. 1 is a system diagram showing an embodiment of a flow rate detection device according to the present disclosure. A physical quantity detection device 100 shown in FIG. 1 is an embodiment of a flow rate detection device according to the present disclosure, and is used, for example, in an electronic fuel injection type internal combustion engine control system 1. The internal combustion engine control system 1 includes, for example, an internal combustion engine 10, a physical quantity detection device 100, a throttle valve 25, a throttle angle sensor 26, an idle air control valve 27, an oxygen sensor 28, and a control device 4. There is.

For example, the physical quantity detection device 100 is inserted into the main passage 22 through a mounting hole provided in the passage wall of the intake body, which is the main passage 22, and is used while being fixed to the passage wall of the main passage 22. The physical quantity detection device 100 detects a physical quantity of intake air, which is the gas to be measured 2 taken in through the air cleaner 21 and flows through the main passage 22 , and outputs it to the control device 4 .

The physical quantity detection device 100 protrudes in the radial direction of the main passage 22 from the passage wall of the main passage 22 toward the center line 22 a of the main passage 22 along the main flow direction of the gas to be measured 2 flowing through the main passage 22 . That is, the protruding direction of the physical quantity detection device 100 in the main passage 22 is, for example, a direction perpendicular to the center line 22a of the main passage 22.

Below, an orthogonal coordinate system consisting of an X axis parallel to the protruding direction of the physical quantity detection device 100 in the main passage 22, a Y axis parallel to the center line 22a of the main passage 22, and a Z axis perpendicular to the X axis and the Y axis will be described. Each part of the physical quantity detection device 100 may be explained using the following.

The throttle valve 25 is built in, for example, a throttle body 23 disposed upstream of the intake manifold 24 in the flow direction of the gas to be measured 2 . The control device 4 changes the opening degree of the throttle valve 25 based on the operation amount of the accelerator pedal, for example, and controls the flow rate of intake air as the gas to be measured 2 flowing into the combustion chamber in the cylinder 11 of the internal combustion engine 10. do. The throttle angle sensor 26 measures the opening degree of the throttle valve 25 and outputs it to the control device 4 . Idle air control valve 27 controls the amount of air that bypasses throttle valve 25.

The internal combustion engine 10 includes, for example, a cylinder 11, a piston 12, a spark plug 13, a fuel injection valve 14, an intake valve 15, an exhaust valve 16, and a rotation angle sensor 17. Intake air taken in through the air cleaner 21 based on the operation of the piston 12 of the internal combustion engine 10 flows through the main passage 22, and its flow rate is controlled by the throttle valve 25 in the throttle body 23. The intake air that has passed through the throttle body 23 passes through an intake manifold 24, further passes through a fuel injection valve 14 provided at an intake port, and flows into a combustion chamber within the cylinder 11 via an intake valve 15.

The control device 4 controls the fuel injection valve 14 based on the physical quantity of the intake air as the gas to be measured 2 inputted from the physical quantity detection device 100 to inject fuel into the intake air. As a result, the intake air that has passed through the intake manifold 24 is mixed with the fuel injected from the fuel injection valve 14, and is guided into the combustion chamber in the form of an air-fuel mixture. The control device 4 explosively burns the air-fuel mixture in the combustion chamber by spark ignition from the spark plug 13, and causes the internal combustion engine 10 to generate mechanical energy.

The rotation angle sensor 17 detects information regarding the positions and states of the piston 12, the intake valve 15, and the exhaust valve 16, as well as the rotational speed of the internal combustion engine 10, and outputs the information to the control device 4. Gas generated by combustion is discharged from the combustion chamber of the cylinder 11 to the exhaust pipe via the exhaust valve 16, and is discharged as exhaust gas 3 to the outside of the vehicle from the exhaust pipe. The oxygen sensor 28 is provided in the exhaust pipe, measures the oxygen concentration of the exhaust gas 3 flowing through the exhaust pipe, and outputs the measured oxygen concentration to the control device 4 .

The control device 4 controls each part of the internal combustion engine control system 1 based on the physical quantities of the intake air as the gas to be measured 2 flowing through the main passage 22 detected by the physical quantity detection device 100, such as flow rate, temperature, humidity, pressure, etc. control. Specifically, when the control device 4 controls the opening degree of the throttle valve 25 based on the operation amount of the accelerator pedal, the flow rate of intake air as the gas to be measured 2 flowing through the main passage 22 changes. The control device 4 controls the amount of fuel injected from the fuel injection valve 14 based on the flow rate of the gas to be measured 2 detected by the physical quantity detection device 100, for example. Thereby, the mechanical energy generated by the internal combustion engine 10 is controlled.

The control device 4 calculates the fuel injection amount and ignition timing based on the physical quantity of intake air, which is the output of the physical quantity detection device 100, and the rotation speed of the internal combustion engine 10, which is measured based on the output of the rotation angle sensor 17. do. Based on these calculation results, the control device 4 controls the amount of fuel injected by the fuel injection valve 14 and the ignition timing of the spark plug 13.

In reality, the control device 4 further determines the fuel level based on the temperature of the gas to be measured 2, the changing state of the opening degree of the throttle valve 25, the changing state of the rotational speed of the internal combustion engine 10, and the state of the air-fuel ratio of the exhaust gas 3. The supply amount and ignition timing are precisely controlled. The control device 4 further controls the amount of air bypassing the throttle valve 25 using the idle air control valve 27 when the internal combustion engine 10 is in an idling operating state, and controls the rotational speed of the internal combustion engine 10 in the idling operating state.

The fuel supply amount and ignition timing, which are the main control variables of the internal combustion engine 10, are both calculated using the output of the physical quantity detection device 100 as a main parameter. Therefore, improving the measurement accuracy, suppressing changes over time, and improving the reliability of the physical quantity detection device 100 are important for improving the control accuracy and ensuring reliability of the vehicle.

Particularly in recent years, there has been a very high demand for fuel efficiency of vehicles, and also a very high demand for exhaust gas purification. In order to meet these demands, it is extremely important to improve the detection accuracy of the physical quantity of intake air detected by the physical quantity detection device 100. It is also important that the physical quantity detection device 100 maintains high reliability.

A vehicle equipped with the physical quantity detection device 100 is used in an environment with large changes in temperature and humidity. It is desirable for the physical quantity detection device 100 to take into account measures such as changes in temperature and humidity in the environment in which it is used, as well as measures against dust and pollutants.

Further, the physical quantity detection device 100 is attached to an intake pipe that is affected by heat generated from the internal combustion engine. Therefore, heat generated by the internal combustion engine is transmitted to the physical quantity detection device 100 via the intake pipe. Since the physical quantity detection device 100 detects the flow rate of the gas to be measured 2 by performing heat transfer with the gas to be measured 2, it is important to suppress the influence of heat from the outside as much as possible.

FIG. 2 is a schematic cross-sectional view of the physical quantity detection device 100 shown in FIG. The physical quantity detection device 100 includes a housing 110 and a cover (not shown). Housing 110 is manufactured, for example, by injection molding a synthetic resin material. The cover is, for example, a plate-shaped member made of metal or synthetic resin. For the cover, for example, a molded product made of a synthetic resin material can be used. The housing 110 and the cover constitute a casing of the physical quantity detection device 100 disposed within the main passage 22. The housing 110 includes, for example, a flange 111, a connector 112, and a measuring section 113.

The flange 111 has, for example, a through hole into which a fixing screw is inserted. The physical quantity detection device 100 can be installed in the main passage by inserting the measuring part 113 of the housing 110 into the mounting hole of the main passage 22 and screwing the fixing screw inserted into the through hole of the flange 111 into the screw hole of the main passage 22. It is fixed to the passage wall of 22.

The connector 112 protrudes from the flange 111, is disposed outside the main passage 22 that is the intake body, and is connected to external equipment. Inside the connector 112, a plurality of external terminals and correction terminals (not shown) are provided. The external terminals include, for example, output terminals for physical quantities such as flow rate and temperature, which are measurement results of the physical quantity detection device 100, and power terminals for supplying DC power to operate the physical quantity detection device 100.

External terminals of the connector 112 are connected to the chip package 150 via a lead frame 154, for example. The chip package 150 includes a lead frame 154, a resin sealing section 155 that partially seals the lead frame 154, and a detection section 151 that detects the flow rate of gas. The detection unit 151 is, for example, a thermal flow sensor. Details of the detection unit 151 will be described later.

The chip package 150 has a configuration in which the detection section 151 and the electronic component are integrally sealed with a resin sealing section 155 molded by transfer molding of thermosetting resin, for example. The chip package 150 drives the detection section 151 by, for example, an electronic component such as an LSI connected to the detection section 151. The detection unit 151 is exposed, for example, at the center of the bottom of a groove provided at the tip of the chip package 150. The groove of the chip package 150 is provided along the flow direction of the gas 2 to be measured.

The measuring portion 113 extends from a flange 111 fixed to a passage wall of the main passage 22 toward the center line 22a of the main passage 22 so as to protrude in the radial direction of the main passage 22 perpendicular to the center line 22a. The measurement unit 113 has a flat rectangular shape that is generally a rectangular parallelepiped. The measurement section 113 has a length in the protruding direction of the measurement section 113 in the main passage 22 (X-axis direction), and a width in the flow direction of the gas to be measured 2 in the main passage 22 (Y-axis direction). There is.

Furthermore, the measurement section 113 has a thickness in the direction (Z-axis direction) perpendicular to the protruding direction (X-axis direction) and the flow direction (Y-axis direction) of the gas to be measured 2 . In this way, since the measuring section 113 has a flat shape along the main flow direction of the gas to be measured 2, fluid resistance to the gas to be measured 2 can be reduced. The measurement unit 113 has a sub-passage inlet 114 on the upstream side, and a sub-passage outlet 115 on the downstream side.

The sub-passage inlet 114 and the sub-passage outlet 115 are provided at the distal end of the measuring section 113 on the distal side of the center in the protruding direction (X-axis direction) of the measuring section 113. Thereby, the gas to be measured 2 near the center of the main passage 22, which is away from the inner wall surface of the main passage 22, can be taken in from the sub passage entrance 114. Therefore, the physical quantity detection device 100 can suppress a decrease in measurement accuracy due to the influence of heat of the internal combustion engine 10.

The sub-passage inlet 114 and the sub-passage outlet 115 are, for example, the inlet and outlet of the sub-passage 130 formed between the housing 110 and the cover. The sub passage 130 is provided in a spiral shape so that the gas to be measured 2 taken in from the sub passage inlet 114 is rotated by 360 degrees and discharged from the sub passage outlet 115. A portion of the chip package 150 excluding the tip is accommodated in the circuit chamber 116 of the housing 110, and the tip of the chip package 150 projects into the sub passage 130. As a result, the groove at the tip of the chip package 150 is arranged at the top of the spiral sub-path 130, approximately parallel to the centerline 22a of the main passage 22.

Furthermore, the measurement unit 113 of the housing 110 includes an intake air temperature sensor 120 that is provided to protrude toward the upstream side (Y-axis negative direction) of the flow direction of the gas to be measured 2 . The intake air temperature sensor 120 detects the temperature of the gas to be measured 2 flowing through the main passage 22 and outputs a signal corresponding to the detected temperature to the output terminal of the connector 112.

FIG. 3 is a schematic plan view of the detection unit 151 shown in FIG. 2. FIG. 4 is a schematic cross-sectional view of the detection unit 151 taken along line IV-IV in FIG. 3. As described above, the detection unit 151 is, for example, a thermal flow sensor, and includes a pair of temperature detection units 151a arranged apart from each other in the direction in which the gas to be measured 2 flows (Y-axis direction), and It has a heating part 151b arranged between the detection parts 151a. Further, the detection unit 151 further includes, for example, a heating temperature detection unit 151c arranged between a pair of temperature detection units 151a and heating unit 151b.

The pair of temperature detecting portions 151a and heating portions 151b are formed, for example, by wiring that meanders back and forth along the direction (X-axis direction) orthogonal to the flow direction (Y-axis direction) of the gas to be measured 2. ing. Further, the heating temperature detecting section 151c is provided, for example, around the heating section 151b so as to surround the heating section 151b on three sides, and is arranged between the pair of temperature detecting sections 151a and the heating section 151b. The material of the temperature detection section 151a, the heating section 151b, and the heating temperature detection section 151c may be, for example, a semiconductor material such as polycrystalline silicon or single crystal silicon doped with impurities, or a material such as platinum, molybdenum, tungsten, or a nickel alloy. Metal materials can be used.

For example, a plurality of wires 151d are connected to the detection unit 151 that detects the flow rate of the gas to be measured 2. More specifically, in the pair of temperature detecting sections 151a of the detecting section 151, wiring 151d is connected to both ends of one temperature detecting section 151a and to both ends of the other temperature detecting section 151a, respectively. Furthermore, a wiring 151d is also connected to one end of the heating temperature detection section 151c. Each wiring 151d extends, for example, along the flow direction of the gas to be measured 2 (Y-axis direction). Further, one end and the other end of the heating section 151b are each connected to a terminal 151e, for example. As the material for the wiring 151d, for example, the same material as the temperature detection section 151a, heating section 151b, and heating temperature detection section 151c can be used.

Further, the detection unit 151 includes, for example, a substrate 160 and a protective film 170 formed on the surface of the substrate 160, as shown in FIG. As the material of the substrate 160, for example, a material with high thermal conductivity such as a semiconductor such as silicon or a ceramic can be used.

The protective film 170 is, for example, a plurality of electrically insulating thin films formed on the surface of the substrate 160, such as silicon dioxide or silicon nitride. The protective film 170 includes, for example, an oxide film formed on the surface of the substrate 160, an oxide film formed on the oxide film and covering the temperature detecting section 151a, the heating section 151b, and the heating temperature detecting section 151c, and It includes a nitride film formed on an oxide film and an oxide film formed on the nitride film. The protective film 170 has a thickness of, for example, about 2 μm, which provides a sufficient thermal insulation effect. Further, the surface of the protective film 170 opposite to the surface facing the substrate 160 is exposed to the sub passage 130 which is a flow path for the gas to be measured 2 .

The substrate 160 has, for example, a cavity 161. The cavity 161 is formed, for example, by removing a part of the substrate 160 by etching from the back side of the substrate 160 that is opposite to the front surface of the substrate 160 on which the protective film 170 is formed. A part of the back surface of the protective film 170 facing the substrate 160 is exposed by the cavity 161, and a diaphragm 171 is formed by the protective film 170 at one end of the cavity 161. The temperature detection section 151a, the heating section 151b, the heating temperature detection section 151c, and the wiring 151d are provided on the diaphragm 171 of the protective film 170, for example.

As shown in FIG. 4, the physical quantity detection device 100 further includes a charge removal wiring 180 connected to the ground and covered with a protective film 170. As for the material of the charge removal wiring 180, for example, similarly to the wiring 151d, a semiconductor material such as polycrystalline silicon or single crystal silicon doped with impurities, or a metal material such as platinum, molybdenum, tungsten, or nickel alloy is used. be able to. The impedance of the charge removal wiring 180 is, for example, lower than the impedance of the wiring 151d. The charge removal wiring 180 is formed, for example, on the oxide film constituting the protective film 170 together with a pair of temperature detection parts 151a, heating parts 151b, and heating temperature detection parts 151c, and is further formed on the oxide film constituting the protective film 170. covered by a film, a nitride film, and an oxide film.

The distance d1 from the sub-passage 130, which is a flow path for the gas to be measured 2, to the charge removal wiring 180 is set to be equal to or less than the distance d2 from the sub-passage 130 to the wiring 151d. In the example shown in FIG. 4, the distance d1 from the sub-path 130 to the charge removal wiring 180 is equal to the distance d2 from the temperature detection section 151a and the heating section 151b to the sub-path 130. That is, in the example shown in FIG. 4, the distance d1 from the sub-path 130 to the charge removal wiring 180 is equal to the distance d2 from the sub-path 130 to each wiring 151d shown in FIG.

As shown in FIG. 3, the charge removal wiring 180 is arranged, for example, along the wiring 151d connected to the detection unit 151, on both sides of the wiring 151d. More specifically, the wiring 151d connected to one end and the other end of each temperature detection part 151a of the detection part 151 respectively extends along the flow direction of the gas to be measured 2 (Y-axis direction). . Then, on both sides of each wiring 151d in a direction (X-axis direction) that intersects the flow direction of the gas to be measured 2, which is the width direction of each wiring 151d, charge removal wiring 180 is connected to each wiring 151d along each wiring 151d. extending in parallel.

Further, a wiring 151d connected to one end of the heating temperature detection section 151c of the detection section 151 also extends along the flow direction of the gas to be measured 2 (Y-axis direction). Then, on both sides of the wiring 151d in a direction (X-axis direction) that intersects the flow direction of the gas to be measured 2, which is the width direction of the wiring 151d, charge removal wiring 180 is provided along and parallel to the wiring 151d. It is extending.

Furthermore, the charge removal wiring 180 is arranged so as to surround each temperature detection part 151a of the pair of temperature detection parts 151a and the wiring 151d extending from each temperature detection part 151a. More specifically, the charge removal wiring 180 surrounds each temperature detection section 151a from all sides, and extends along each temperature detection section 151a on both sides of each detection section 151 extending from each temperature detection section 151a. It is located.

Hereinafter, the operation of the physical quantity detection device 100 of this embodiment will be explained.

As described above, the physical quantity detection device 100 is used while being fixed to the passage wall of the intake body, which is the main passage 22, for example. The physical quantity detection device 100 takes, for example, intake air, which is the gas to be measured 2 taken in through the air cleaner 21 and flows through the main passage 22, into the sub passage 130 from the sub passage entrance 114 provided in the measurement section 113 of the housing 110. The gas to be measured 2 taken into the sub-pathway 130 flows along the detection section 151 shown in FIG.

In conventional flow rate detection devices, for example, when gas flows along the detection section, the detection section that detects the flow rate of the gas may be charged with static electricity. When the detection section is charged with static electricity, the charged dust contained in the gas is attracted to the detection section by the electrostatic force, which may reduce the accuracy of flow rate detection by the detection section. Further, if electrostatic discharge occurs in the signal wiring connected to the detection section, the protective film covering the signal wiring is damaged and the signal wiring is exposed, and there is a risk that the signal wiring may be disconnected due to corrosion, for example.

In contrast, the physical quantity detection device 100, which is an embodiment of the flow rate detection device according to the present disclosure, has the following configuration. The physical quantity detection device 100 includes a detection section 151 that detects the flow rate of the gas to be measured 2, a wiring 151d connected to the detection section 151, and a wire that covers the detection section 151 and the wiring 151d and is exposed to the flow path of the gas to be measured 2. A protective film 170 is provided. The physical quantity detection device 100 further includes a charge removal wiring 180 connected to the ground and covered with a protective film 170. The distance d1 from the sub-passage 130, which is a flow path for the gas to be measured 2, to the charge removal wiring 180 is less than or equal to the distance d2 from the sub-passage 130 to the wiring 151d.

With such a configuration, charges can be released to the ground by the charge removal wiring 180, and charging of the protective film 170 covering the detection unit 151, the wiring 151d, etc. can be suppressed. As a result, as shown in FIG. 4, it is possible to reduce the electrostatic force that attracts the dust D contained in the gas to be measured 2, increase the amount of dust D passing through the detection section 151, and improve the stain resistance of the detection section 151. can be improved. Therefore, according to the physical quantity detection device 100 according to an embodiment of the flow rate detection device of the present disclosure, variation in the characteristics of the detection unit 151 can be suppressed.

Furthermore, since the charge removal wiring 180 is connected to the ground, even if electrostatic discharge ESD occurs, as shown in FIG. ESD occurs. This prevents electrostatic discharge ESD to the temperature detection section 151a and the wiring 151d, prevents part of the temperature detection section 151a and the wiring 151d from being exposed from the protective film 170 and corrodes, and detects the detection section 151. In addition to preventing variations in characteristics, it is possible to suppress disconnection of the temperature detection section 151a and the wiring 151d. Note that even if, for example, electrostatic discharge ESD occurs on the charge removal wiring 180 and a pinhole PH is formed in the protective film 170 and a part of the charge removal wiring 180 is exposed from the protective film 170, the detection unit 151 cannot detect the static electricity. It has no negative effect on the characteristics.

Further, in the physical quantity detection device 100 according to an embodiment of the flow rate detection device of the present disclosure, the detection unit 151 includes a pair of temperature detection units 151a arranged apart from each other in the direction in which the gas to be measured 2 flows; The heating section 151b is arranged between the temperature detection sections 151a. Moreover, the wiring 151d extends along the direction in which the gas to be measured 2 flows from the pair of temperature detection parts 151a. With such a configuration, when the gas to be measured 2 passes through the detection section 151, the gas heated by the heating section 151b is directed to the temperature detection section 151a on the downstream side of the gas to be measured 2, of the pair of temperature detection sections 151a. Moving. This causes a difference in the temperatures detected by the pair of temperature detection sections 151a. The detection unit 151 can detect the flow rate of the gas to be measured 2 based on the temperature difference detected by the pair of temperature detection units 151a.

Further, in the physical quantity detection device 100 according to an embodiment of the flow rate detection device of the present disclosure, the charge removal wiring 180 is arranged on both sides of each wiring 151d along each wiring 151d. With such a configuration, charging of each wiring 151d can be more effectively prevented, and the stain resistance of the detection section 151 can be further improved. Further, each wiring 151d extending from each temperature detection part 151a along the flow direction of the gas to be measured 2 is more reliably protected from electrostatic discharge ESD by the charge removal wiring 180 arranged on both sides of each wiring 151d. can be protected.

Furthermore, in the physical quantity detection device 100 according to an embodiment of the flow rate detection device of the present disclosure, the charge removal wiring 180 connects each temperature detection portion 151a of the pair of temperature detection portions 151a and the wiring 151d extending from the temperature detection portion 151a. arranged to surround. With such a configuration, it is possible to more effectively prevent each temperature detection section 151a and each wiring 151d from being charged, and further improve the stain resistance of the detection section 151. Further, each temperature detection section 151a and each wiring 151d extending from each temperature detection section 151a can be more reliably protected from electrostatic discharge ESD by the charge removal wiring 180 arranged around them.

In the physical quantity detection device 100 according to an embodiment of the flow rate detection device of the present disclosure, the detection unit 151 further includes a heating temperature detection unit 151c disposed between the heating unit 151b and the pair of temperature detection units 151a. . With this configuration, the temperature of the gas near the heating section 151b can be measured by the heating temperature detection section 151c, and the detection accuracy of the flow rate of the gas to be measured 2 by the detection section 151 can be further improved. Furthermore, the charge removal wiring 180 disposed along the wiring 151d extending from the heating temperature detection section 151c can prevent the wiring 151d from being charged and prevent electrostatic discharge ESD from occurring on the wiring 151d.

Further, in the physical quantity detection device 100 according to an embodiment of the flow rate detection device of the present disclosure, the impedance of the charge removal wiring 180 is lower than the impedance of the wiring 151d. With this configuration, charging of each wiring 151d can be more effectively prevented, and the stain resistance of the detection section 151 can be further improved. Moreover, each wiring 151d can be more reliably protected from electrostatic discharge ESD by the charge removal wiring 180.

As described above, according to the present embodiment, the physical quantity detection device 100 as a flow rate detection device capable of suppressing the charged dust D contained in the gas to be measured 2 from being adsorbed by the detection unit 151 is provided. can be provided. Note that the flow rate detection device according to the present disclosure is not limited to the above-described embodiments. Hereinafter, some modified examples of the physical quantity detection device 100 according to the above-described embodiment will be described.

FIG. 5 is a schematic cross-sectional view showing a first modification of the detection unit 151 shown in FIG. 4. In the physical quantity detection device 100 as a flow rate detection device of this modification, the distance d1 from the sub-passage 130, which is the flow path for the gas to be measured 2, to the charge removal wiring 180 is longer than the distance d2 from the sub-passage 130 to the wiring 151d. close. With such a configuration, it is possible to more reliably prevent the wiring 151d and the like from being charged, and to more reliably protect the wiring 151d and the like from electrostatic discharge ESD.

FIG. 6 is a schematic cross-sectional view showing a second modification of the detection unit 151 shown in FIG. 4. In the physical quantity detection device 100 as a flow rate detection device of this modification, the distance d1 from the sub-passage 130, which is the flow path for the gas to be measured 2, to the charge removal wiring 180 is longer than the distance d2 from the sub-passage 130 to the wiring 151d. close. Further, the charge removal wiring 180 covers at least a portion of the pair of temperature detection parts 151a, the heating part 151b, and the wiring 151d. With such a configuration, it is possible to more reliably prevent the wiring 151d and the like from being charged, and to more reliably protect the wiring 151d and the like from electrostatic discharge ESD.

Although the embodiment of the flow rate detection device according to the present disclosure has been described above in detail using the drawings, the specific configuration is not limited to this embodiment, and design changes may be made within the scope of the gist of the present disclosure. etc., they are included in the present disclosure.

2 Gas to be measured (gas)
100 Physical quantity detection device (flow rate detection device)
130 Sub-passage (flow path)
151 Detection section 151a Temperature detection section 151b Heating section 151c Heating temperature detection section 151d Wiring 170 Protective film 180 Charge removal wiring d1 Distance d2 Distance

Claims (4)

A flow rate detection device comprising: a detection unit that detects a gas flow rate; wiring connected to the detection unit; and a protective film that covers the detection unit and the wiring and is exposed to the gas flow path. hand,
further comprising a charge removal wiring connected to ground and covered with the protective film,
The distance from the flow path to the charge removal wiring is less than or equal to the distance from the flow path to the wiring,
The detection unit includes a pair of temperature detection units arranged apart from each other in the direction in which the gas flows, and a heating unit arranged between the pair of temperature detection units,
The wiring extends from the pair of temperature detection parts along the direction in which the gas flows,
A flow rate detection device characterized in that the charge removal wiring is arranged on both sides of the wiring along the wiring. 2. The flow rate detection device according to claim 1 , wherein the charge removal wiring is arranged to surround each temperature detection part of the pair of temperature detection parts and the wiring extending from the temperature detection part. The flow rate detection device according to claim 2 , wherein the detection section further includes a heating temperature detection section disposed between the heating section and the pair of temperature detection sections. The flow rate detection device according to claim 1, wherein the impedance of the charge removal wiring is lower than the impedance of the wiring.

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