Gas sensor, gas detection device, gas detection method and electric equipment

Abstract

The invention provides a gas sensor, a gas detection device, a gas detection method, and a device including the gas sensor and the gas detection device, wherein the gas detection performance can be improved and the deviation of the output characteristics of each gas sensor can be suppressed. A gas detection device (10) is provided with: a gas sensor (1) having a heat-sensitive resistance element (2), a lead part (22b) connected to the heat-sensitive resistance element (2) in a state in which the lead part (22b) is welded to the heat-sensitive resistance element (2) without inclusions, and a porous gas molecule-adsorbing material (3) that adsorbs gas molecules from the heat-sensitive resistance element (2) in the state in which the lead part (22b) is welded to the heat-sensitive resistance element (2); a porous gas molecule adsorption material (3) which is thermally coupled to the thermal resistance element (2) and desorbs specified gas molecules by heating; and a power supply unit that supplies power to the heat-sensitive resistance element (2) and heats the heat-sensitive resistance element (2).

Description

[0001] This application is filed on July 26, 2018, with application number

[0002] CN201880051078.2, divisional application of the patent application with the invention name of "Gas sensor, gas detection device, gas detection method and device including gas sensor and gas detection device". Technical Field

[0003] The present invention relates to a gas sensor capable of detecting gas molecules, a gas detection device, a gas detection method and a device comprising the gas sensor and the gas detection device. Background Art

[0004] Conventionally, humidity sensors or gas sensors have been used as gas detection devices to detect humidity or a specific gas, for example, in home appliances or office automation (OA) equipment, food storage equipment, medical equipment, and transportation equipment such as automobiles.

[0005] Such a gas detection device needs to improve the gas detection sensitivity at low temperatures or the gas selectivity of selecting a gas to be detected.

[0006] Furthermore, there is known a humidity sensor including a humidity sensing resistor element formed by surrounding a metal resistor wire with type A zeolite, for example, molecular sieve 5A (see Patent Documents 1 and 2).

[0007] In order to make the gas sensor resistant to siloxane gas for a long time and improve the gas selectivity, a sensor has been proposed in which a filter including zeolite, activated alumina, etc. is provided on a cover that accommodates the sensor body (see Patent Document 3).

[0008] Furthermore, a humidity sensor using a sensor element including a sensor chip or a humidity sensor using a humidity-sensitive thin film formed by polymerizing a monomer has been proposed (see Patent Documents 4 and 5). In addition, a hydrogen sensor has been proposed that uses palladium as a hydrogen absorbing material and detects hydrogen by causing the solid palladium to undergo a chemical reaction as a hydrogenation reaction to absorb hydrogen (see Patent Document 6).

[0009] Prior art literature

[0010] Patent Literature

[0011] Patent Document 1: Japanese Patent Laid-Open No. 2-85753

[0012] Patent Document 2: Japanese Patent Laid-Open No. 3-220448

[0013] Patent Document 3: Japanese Patent Application Publication No. 2013-242269

[0014] Patent Document 4: Utility Model Registration No. 3173006

[0015] Patent Document 5: Japanese Patent Application Publication No. 2003-262600

[0016] Patent Document 6: WO2014 / 189119 Summary of the invention

[0017] Problems to be solved by the invention

[0018] However, the above-mentioned conventional humidity sensors are based on the following principle: the humidity is detected by detecting the change in the resistance value corresponding to the water vapor content in the environment. Moreover, the humidity sensors shown in Patent Documents 1 and 2 are energized to the metal resistance wire, and the metal resistance wire is adjusted to a high temperature in a range of 300°C to 500°C, which has the following problems: the energy used to heat the metal resistance wire is large, the power consumption becomes large, and the life is also short.

[0019] In addition, the gas sensor disclosed in Patent Document 3 is particularly provided with filters such as zeolite, activated alumina and activated carbon, and the humidity sensors disclosed in Patent Documents 4 and 5 have the problem of low gas detection sensitivity at low temperatures. Furthermore, in Patent Document 6, since the detection principle is based on chemical reaction, inert gases such as helium cannot be detected because no chemical reaction occurs.

[0020] The present invention is made in view of the above-mentioned problems, and its object is to provide a gas sensor, a gas detection device, a gas detection method and a device including the gas sensor and the gas detection device, which can improve the gas detection performance and suppress the deviation of the output characteristics of each gas sensor.

[0021] Technical means of solving problems

[0022] The gas sensor according to technical solution 1 is characterized in that it includes: a thermally sensitive resistor element having at least a pair of electrodes; a lead portion connected to the thermally sensitive resistor element in a state of being fused to the thermally sensitive resistor element without inclusions; and a porous gas molecule adsorption material that is thermally coupled to the thermally sensitive resistor element and desorbs specified gas molecules by heating.

[0023] As a porous gas molecule adsorbing material, zeolite or porous metal complex can be used. As zeolite, for example, molecular sieve of type A zeolite can be suitably used. Porous metal complex is a new material of coordinated polymer or organic-metal framework obtained by utilizing metal complex.

[0024] The gas sensor according to Technical Solution 2 is characterized in that: in the gas sensor according to Technical Solution 1, the thermal conductivity of the lead part is 5W / m·k~25W / m·k, the cross-sectional area is 0.001mm2~0.03mm2, and it is formed of a material that can be welded.

[0025] According to the invention, the heat capacity is reduced, thereby realizing a gas sensor with high sensitivity and excellent thermal responsiveness.

[0026] The gas sensor according to Technical Solution 3 is characterized in that: in the gas sensor according to Technical Solution 1 or 2, the thermally sensitive resistor element is formed by forming a thin film element layer on a substrate, and the thickness of the substrate is 10 μm to 100 μm.

[0027] According to the invention, the total thickness of the sensor is reduced and the heat capacity is reduced, thereby realizing a gas sensor with high sensitivity and excellent thermal responsiveness.

[0028] The gas sensor according to Technical Solution 4 is characterized in that: in the gas sensor according to any one of Technical Solutions 1 to 3, the porous gas molecule adsorption material is formed by film formation on the surface of the thermal resistor element, and the thickness of the film-formed porous gas molecule adsorption material is 1μm to 5μm.

[0029] According to the invention, the heat capacity is reduced, thereby realizing a gas sensor with high sensitivity and excellent thermal responsiveness.

[0030] The gas sensor according to technical solution 5 is characterized in that: in the gas sensor according to any one of technical solutions 1 to 4, the lead part is formed in a foil-like lead frame shape.

[0031] According to the invention, the total thickness of the sensor is reduced and the heat capacity is reduced, thereby realizing a gas sensor with high sensitivity and excellent thermal responsiveness.

[0032] The gas sensor according to Technical Solution 6 is characterized in that: in the gas sensor according to any one of Technical Solutions 1 to 5, the heat-sensitive resistor element is a thermistor.

[0033] By using a thermistor, the thermal runaway phenomenon unique to thermistors can be utilized, thereby making the gas sensor highly sensitive.

[0034] The gas sensor according to Technical Solution 7 is characterized in that: in the gas sensor according to any one of Technical Solutions 1 to 6, it includes a heating and / or cooling element that maintains the gas sensor at a certain temperature.

[0035] The heating and / or cooling element includes an element having a single heating or cooling function, or an element having both heating and cooling functions instead of a single heating or cooling function. For example, a thermoelectric element such as a heater or a Peltier element can be applied.

[0036] By keeping the gas sensor at a constant temperature, various temperature-related interference factors can be reduced, thereby making the gas sensor highly sensitive.

[0037] The gas sensor according to Technical Solution 8 is characterized in that: in the gas sensor according to Technical Solution 7, the heating and / or cooling element is a thermoelectric element.

[0038] The gas detection device according to Technical Solution 9 is characterized in that it includes: a gas sensor according to any one of Technical Solutions 1 to 6; and a heating and / or cooling device to maintain the gas sensor at a certain temperature.

[0039] As the heating and / or cooling device, for example, a temperature regulator including a thermoelectric element can be applied. However, the heating and / or cooling device is not limited to a specific device.

[0040] According to the invention, the gas sensor is kept at a constant temperature, thereby reducing various interference factors related to temperature, thereby making the gas sensor highly sensitive.

[0041] The gas detection method according to technical solution 10 is a gas detection method of a gas sensor, and the gas sensor includes: a thermally sensitive resistor element having at least a pair of electrodes; a lead portion, connected to the thermally sensitive resistor element in a state of being fused to the thermally sensitive resistor element without inclusions; and a porous gas molecule adsorption material, thermally coupled to the thermally sensitive resistor element, and desorbing specified gas molecules by heating. The gas detection method is characterized in that it includes: a step of maintaining the gas sensor at a certain temperature; a heating step of setting the porous gas molecule adsorption material to a heated state; and a detection step of detecting a specified gas by a change in the output of the thermally sensitive resistor element caused by the heating.

[0042] The gas detection method according to Technical Solution 11 is characterized in that: in the gas detection method according to Technical Solution 10, in order to detect a specified gas, the output of a reference gas is measured in advance.

[0043] The gas detection method according to Technical Solution 12 is characterized in that: in the gas detection method according to Technical Solution 11, in the detection step, the concentration of the specified gas is detected by comparing the result of measuring the output of the gas used as a reference in advance with the measurement result of the output of the specified gas.

[0044] The gas detection method according to technical solution 13 is characterized in that: in the gas detection method according to any one of technical solutions 10 to 12, in the heating step, overpower is supplied to the thermally sensitive resistor element to put the thermally sensitive resistor element into a thermal runaway state.

[0045] The gas detection method according to Technical Solution 14 is characterized in that: in the gas detection method according to Technical Solution 13, the certain temperature is below 10°C.

[0046] By lowering the temperature of the gas sensor, the sensor becomes more sensitive and can detect trace amounts of gas.

[0047] The device including a gas sensor according to Technical Solution 15 is characterized in that it includes a gas sensor according to any one of Technical Solutions 1 to 8.

[0048] The device including the gas sensor can be installed in various devices for detecting gas molecules and humidity, such as medical equipment, automobiles, home appliances, OA equipment, food storage equipment, etc. The device to be used is not particularly limited.

[0049] The device including a gas detection device according to Technical Solution 16 is characterized in that it includes the gas detection device according to Technical Solution 9.

[0050] The device including the gas detection device can be installed in various devices for detecting gas molecules and humidity, such as medical equipment, automobiles, home appliances or OA equipment, food storage equipment, etc. The device used is not particularly limited.

[0051] Effects of the Invention

[0052] According to the present invention, a gas sensor, a gas detection device, a gas detection method, and a device including the gas sensor and the gas detection device can be provided, which can improve gas detection performance and suppress deviations in output characteristics of each gas sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 It is a cross-sectional view showing a gas sensor according to a first embodiment of the present invention.

[0054] Figure 2 is along Figure 1 Cross-sectional view of line XX in .

[0055] Figure 3 This is a wiring diagram for characteristic detection of the gas detection device according to the first embodiment of the present invention.

[0056] Figure 4 It is a block diagram showing the structure of a gas detection device according to a first embodiment of the present invention.

[0057] Figure 5 It is a diagram schematically showing a configuration example of a measuring method of the gas detection device according to the first embodiment of the present invention.

[0058] Figure 6 Graphs for explaining output characteristics of a gas sensor and showing voltage applied to the sensor with respect to hydrogen concentration at 5°C.

[0059] Figure 7 2 is a graph showing the sensor temperature with respect to the hydrogen concentration at 5° C. similarly.

[0060] Figure 8 3 is a graph showing the sensor output with respect to the hydrogen concentration at 5° C.

[0061] Fig. 9 is with Figure 6 The corresponding figure is a curve graph in which the range of the time axis is changed.

[0062] Fig.10 is with Figure 8 The corresponding figure is a curve graph in which the range of the time axis is changed.

[0063] Fig.11 It is a cross-sectional view showing a gas sensor according to a second embodiment of the present invention.

[0064] Fig.12 This is a wiring diagram for characteristic detection of a gas detection device according to a third embodiment of the present invention.

[0065] Fig.13 The third embodiment of the present invention is a thermally sensitive resistor element. Figure 2 Quite a cross-section.

[0066] Explanation of symbols

[0067] 1: Gas sensor

[0068] 2: Thermal resistance element for detection

[0069] 2a: Compensation thermal resistor element

[0070] 3: Gas molecule adsorption component [gas molecule adsorption material]

[0071] 3a: Materials with different adsorption properties

[0072] 4: Base component

[0073] 5: External shell

[0074] 8: Heating and / or cooling elements

[0075] 10: Gas detection device

[0076] 10a: Detection circuit part

[0077] 12: Microcomputer

[0078] 17: Power circuit

[0079] 18: Heating and / or cooling device (temperature control unit)

[0080] 21: Substrate

[0081] 22: Conductive layer

[0082] 22b: Lead wire

[0083] 23: Thin film component layer

[0084] 24: Protective insulation layer

[0085] 42: Conductive terminal

[0086] 51: Ventilation

[0087] Te: Thermoelectric element DETAILED DESCRIPTION

[0088] Below, refer to Figures 1 to 10 Next, a gas sensor, a gas detection device, and a gas detection method according to a first embodiment of the present invention will be described. Figure 1 and Figure 2 is a cross-sectional view showing a gas sensor. Figure 3 This is the wiring diagram for characteristic detection of gas detection devices. Figure 4 This is a block diagram showing the structure of a gas detection device. Figure 5 This is a schematic diagram showing an example of the structure of a gas detection device measuring method. Figures 6 to 10 It is a graph used to illustrate the output characteristics of the gas sensor.

[0089] like Figure 1 and Figure 2 As shown, the gas sensor 1 includes a thermal resistor element 2, a gas molecule adsorbing material 3, a base member 4 and an outer casing 5. The gas sensor 1 is a sensor for detecting water vapor gas (water molecules) or hydrogen in the environment. In addition, in each of the drawings, the scale of each component is appropriately changed in order to make each component a recognizable size.

[0090] The thermal resistor element 2 is a thin film thermistor and a detection thermal resistor element, and includes a substrate 21 , a conductive layer 22 formed on the substrate 21 , a thin film element layer 23 , and a protective insulating layer 24 .

[0091] The substrate 21 is roughly rectangular in shape and is formed using insulating ceramics such as aluminum oxide, aluminum nitride, and zirconium oxide or semiconductor materials such as silicon and germanium. An insulating thin film is formed on one surface of the substrate 21 by sputtering. Specifically, the substrate 21 is made of aluminum oxide material and is formed extremely thin, with a thickness of 10 μm to 100 μm.

[0092] By using such an extremely thin substrate 21 for the heat-sensitive resistor element 2 , it is possible to realize a gas sensor 1 having a small heat capacity, high sensitivity, and excellent thermal responsiveness.

[0093] The conductive layer 22 constitutes a wiring pattern and is formed on the substrate 21. The conductive layer 22 is formed by forming a metal thin film by sputtering, and as its metal material, noble metals such as platinum (Pt), gold (Au), silver (Ag), palladium (Pd) or their alloys, such as Ag-Pd alloy, etc. can be applied. In addition, at both ends of the substrate 21, electrode portions 22a electrically connected to the conductive layer 22 are formed integrally with the conductive layer 22.

[0094] The thin film element layer 23 is a thermistor composition and includes an oxide semiconductor having a negative temperature coefficient. The thin film element layer 23 is formed on the conductive layer 22 by sputtering or the like and is electrically connected to the conductive layer 22 .

[0095] The thin film element layer 23 includes, for example, two or more elements selected from transition metal elements such as manganese (Mn), nickel (Ni), cobalt (Co), and iron (Fe). The protective insulating layer 24 is formed in a manner covering the thin film element layer 23 and the conductive layer 22. The protective insulating layer 24 is a protective glass layer formed of borosilicate glass.

[0096] In addition, a metal lead portion 22b is joined and electrically connected to the electrode portion 22a by welding. Specifically, the lead portion 22b is formed of a material with low thermal conductivity such as constantan or Hastelloy (registered trademark), and its thermal conductivity is preferably 5W / m·k to 25W / m·k. The electrode portion 22a and the lead portion 22b are connected in a state of being fused by laser welding. Therefore, the mutual metals of the electrode portion 22a and the lead portion 22b are melted and joined. Therefore, between the electrode portion 22a and the lead portion 22b, there is no additional material such as a filler material (welding material) used during welding, that is, there is no inclusion, so the heat capacity can be reduced, the thermal time constant can be reduced, and the thermal responsiveness of the thermally sensitive resistor element 2 can be accelerated. Furthermore, the lead portion 22b can use a linear body with a circular cross section or a frame-shaped narrow plate-like body. The form of the lead portion 22b is not particularly limited. When the lead portion 22b is a linear body, it is preferably a foil-shaped body with a diameter of 30 μm to 100 μm and a narrow plate-shaped body. When it is a lead frame shape, it is preferably 80 μm to 200 μm in width and 10 μm to 60 μm in thickness. In addition, the cross-sectional area of ​​the lead portion 22b is preferably 0.001 mm2 to 0.03 mm2.

[0097] Thus, by selecting a material of the lead portion 22b that has a thermal conductivity of 5W / m·k to 25W / m·k and is weldable, and setting the cross-sectional area of ​​the lead portion 22b to 0.001mm2 to 0.03mm2, the heat capacity and heat dissipation of the thermally sensitive resistor element 2 can be reduced, thereby realizing a highly sensitive and thermally responsive gas sensor 1. In particular, if a foil is used for the lead portion, the effect is further improved.

[0098] In addition, the heat-sensitive resistor element is not limited to a thin film thermistor, and may include a thin film platinum resistor element. Furthermore, it may be a thermistor element including a metal wire such as a platinum wire and its alloy wire, or a semiconductor such as a metal oxide, silicide, or nitride.

[0099] The gas molecule adsorbent 3 is thermally coupled to the thus constructed thermal resistor element 2. Specifically, the gas molecule adsorbent 3 is formed in a film-like state on the surface of the thermal resistor element 2. More specifically, the gas molecule adsorbent 3 is maintained in a state of being formed on the surface of the protective insulating layer 24 and the surface on the other side (back side) of the substrate 21.

[0100] Therefore, the thermally sensitive resistor element 2 and the gas molecule adsorbent 3 are thermally coupled to the thin film element layer 23 via the protective insulating layer 24 and the substrate 21. That is, heat is mutually conducted between the thermally sensitive resistor element 2 and the gas molecule adsorbent 3.

[0101] The gas molecule adsorbent 3 is a porous adsorbent, for example, a molecular sieve 3A of type A zeolite (pore diameter 0.3 nm) is formed into a film on the surface of the thermal resistor element 2. When forming the gas molecule adsorbent 3, water and sodium silicate are added as Si sources, and water, aluminum hydroxide and sodium hydroxide are added as Al sources, and solutions are prepared respectively, and they are mixed and stirred to prepare a gel. Then, the support (thermal resistor element) that has been seeded in advance is put into an oil bath together with the gel, and hydrothermal synthesis is performed at 100°C for 4 hours to prepare a membrane.

[0102] The thickness of the gas molecule adsorbent 3 is 1 μm to 5 μm. In this way, an extremely thin functional film can be formed on the thermal resistor element 2, thereby realizing a gas sensor 1 with reduced heat capacity, high sensitivity, and excellent thermal responsiveness. In addition, the film forming method of the gas molecule adsorbent 3 is not particularly limited to a specific method.

[0103] In addition, as the gas molecule adsorbent 3, molecular sieve 4A, molecular sieve 5A, molecular sieve 13X, high silica type zeolite, silver zeolite substituted with metal ions, or porous metal complex can be used depending on the detection target gas.

[0104] The base member 4 is a metal member formed in a substantially disk shape, and a conductive terminal portion 42 is inserted through an insulating member 41. The lead portion 22b led out from the thermal resistor element 2 is electrically connected to the conductive terminal portion 42 by welding, soldering, etc. The insulating member 41 is made of an insulating material such as glass or resin.

[0105] In addition, when the base member 4 is made of an insulating material, it is not necessary to provide the insulating member 41. In addition, the conductive terminal portion 42 may also include a printed wiring board or the like.

[0106] The outer case 5 is a metal member having good thermal conductivity and formed in a substantially cylindrical shape, and has an opening at one end and a circular opening 52 provided with a vent 51 at the other end. One end of the outer case 5 is attached to the base member 4 to cover and protect the thermally sensitive resistor element 2.

[0107] The vent 51 includes a breathable member that can reduce the influence of external wind and allow gas to flow out / in, and is preferably made of a metal mesh, a non-woven fabric, a porous sponge, etc. The vent 51 is pressed into or adhered to the inner circumference of the outer shell 5. In addition, the vent 51 is not limited to the case where it is set in the outer shell 5. It can also be set in the base member 4, and a gap can be formed between the outer shell 5 and the base member 4 and the vent 51 can be set in the said part.

[0108] Furthermore, the outer casing 5 may be made of ceramic or resin material, etc. In such a case, metal plating or the like may be performed so that the inner wall surface of the outer casing 5 has a function of emitting infrared rays.

[0109] like Figure 3 As shown, the gas detection device 10 is constituted by connecting a power source (voltage source) E to a gas sensor 1. Specifically, a resistor 11 and a gas sensor 1 (thermal resistor element 2) are connected in series to the power source E, and an output terminal is connected between the resistor 11 and the thermal resistor element 2, so that the voltage at both ends of the thermal resistor element 2 is used as a voltage applied to the sensor and the output voltage Vout is detected. The resistor 11 is a resistor for overcurrent protection.

[0110] In the gas sensor 1 of the present embodiment as described above, a metal lead portion 22b is joined to the electrode portion 22a of the thermal resistor element 2 by welding, but a gas sensor in which a metal lead portion is joined to the electrode portion by welding is used as a gas sensor of a comparative example, and an attempt is made to compare the output characteristics of the gas sensor 1 of the present embodiment and the gas sensor of the comparative example.

[0111] As a result, it was found that the output characteristics of the gas sensors of the comparative example had large deviations compared to the gas sensor 1 of the present embodiment. This is considered to be due to the presence of inclusions as a filler material (weld material) between the electrode portion and the lead portion in the gas sensor of the comparative example, which easily caused a deviation in the amount of the inclusions, thus affecting the deviation in the output characteristics.

[0112] Therefore, in the gas sensor 1 of the present embodiment, since there are no foreign substances as in the gas sensor of the comparative example, it is possible to suppress variations in the output characteristics of the gas sensors 1 and improve reliability.

[0113] Then, if Figure 4 As shown, in the present embodiment, the gas detection device 10 is controlled by a microcomputer (hereinafter referred to as a "microcomputer") 12 as a control mechanism. In general, the microcomputer 12 includes a central processing unit (CPU) 13 having a calculation unit and a control unit, a read-only memory (ROM) 14 and a random access memory (RAM) 15 as a storage mechanism, and an input / output control mechanism 16. In addition, a power supply circuit 17 is connected to the input / output control mechanism 16. In addition, a power supply circuit 17 is connected to the power supply circuit 17. Figure 3 The circuit shown.

[0114] The power circuit 17 includes the power source E and has a function of supplying and controlling power to the thermally sensitive resistor element 2 by applying the voltage of the power source E to the thermally sensitive resistor element 2. Specifically, the power supplied from the power source E in the power circuit 17 is controlled by a program stored in a storage device of the microcomputer 12. In addition, the output voltage Vout is input to the microcomputer 12 and is output as a detection output after being processed by calculation.

[0115] Furthermore, in the present embodiment, the power supply from the power source E is performed by, for example, a power supply unit including the microcomputer 12 or the power circuit 17. The power supply unit only needs to have a function of supplying power to the gas sensor 1, specifically, a function of supplying power from the power source E to the thermal resistor element 2, and is not particularly limited to a specific member or part.

[0116] Then, in Figure 5 1 shows a configuration example of a gas detection device 10 including a thermoelectric element Te as a temperature adjustment element for maintaining the gas sensor 1 at a certain temperature. In the configuration example, a temperature control unit 18 with a built-in thermoelectric element Te is shown as a heating and / or cooling device for maintaining the gas sensor 1 at a certain temperature. Specifically, the gas detection device 10 includes a thermoelectric element Te. Figure 4 The microcomputer 12 or the detection circuit unit 10a of the power supply circuit 17, and the temperature control unit 18 are shown.

[0117] The detection circuit unit 10 a houses circuit components in a housing, has a display screen 10 p provided on the front surface side, and is connected to the gas sensor 1 via electric wires.

[0118] The temperature control unit 18 is a temperature regulator capable of cooling and heating control, and has a built-in Peltier element as a thermoelectric element Te, and can set the temperature within a range of -20°C to +80°C.

[0119] Furthermore, a mounting member 18a of the gas sensor 1 made of a material with good thermal conductivity such as copper is disposed on a plate (not shown) on the upper surface of the temperature control unit 18. The mounting member 18a has an insertion hole 18b for the gas sensor 1 and a flow hole 18c through which ambient gas can flow.

[0120] The gas sensor 1 is inserted into the insertion hole 18 b , and in the inserted state, gas flows out and in from the vent 51 of the gas sensor 1 through the flow hole 18 c , thereby enabling gas detection.

[0121] Furthermore, the gas detection device 10 includes a heating and / or cooling device, specifically a thermoelectric element Te, for maintaining the gas sensor 1 at a constant temperature. As the thermoelectric element, a Peltier element can be applied, and as the heating element, a heater can be applied. In addition, the constant temperature is preferably an accuracy of ±0.1°C.

[0122] By lowering the temperature of the gas sensor 1, the sensor becomes more sensitive, for example, it can detect trace amounts of gas below 1 ppm. On the other hand, if the temperature of the gas sensor 1 is increased, the gas sensor 1 becomes less sensitive and is more likely to detect high-concentration gas.

[0123] Next, refer to Figure 3 , Figure 4 and Figures 5 to 10 The operation of the gas detection device 10 is described below. In this embodiment, the case where the detection target gas is hydrogen (H2) is shown. For example, the gas detection device is used in a hydrogen station or a fuel cell vehicle in an environment where a predetermined amount of hydrogen (H2) may exist.

[0124] First, the porous gas molecule adsorbent 3 is described. The gas molecule adsorbent 3 is a molecular sieve 3A of type A zeolite (pore diameter 0.3 nm). The gas molecule adsorbent 3 produces a molecular sieving effect and only adsorbs molecules whose molecular diameter is smaller than the pore diameter. Therefore, hydrogen (H2), helium (He), water vapor (water molecules) (H2O) and ammonia (NH3) in the environment are adsorbed, but nitrogen (N2) and oxygen (O2) are not adsorbed. Therefore, the gas can be selectively detected according to the size of the molecule, thereby improving the selectivity of the gas to be detected.

[0125] In general, the temperature changes due to the adsorption and desorption of molecules by the gas molecule adsorbent 3. Therefore, when the gas molecule is hydrogen (H2), the temperature changes when the gas molecule adsorbent 3 is heated to desorb hydrogen (H2).

[0126] Figures 6 to 10 Graph showing the measurement results for explaining the output characteristics of the gas sensor. The gas detection is a case where the concentration of a trace amount of hydrogen (H2) is detected, and the thermal runaway phenomenon of the heat-sensitive resistor element 2 is used.

[0127] As shown in the figure, the ambient temperature (temperature of the gas sensor 1) is kept fixed at 5°C by the thermoelectric element Te, and the voltage of the power supply E is fixed at 3.45V. The voltage (V) applied to the sensor, the temperature of the sensor (°C), and the sensor output (mV) are measured in an environment of 100% nitrogen (N2), 1ppm hydrogen (H2) based on nitrogen (N2), and 2ppm hydrogen (H2) based on nitrogen (N2). The horizontal axis shows the time (seconds), and the vertical axis shows the voltage (mV) output by the sensor. Furthermore, regarding the sensor output, the voltage difference obtained by comparing with the reference is shown with the voltage applied to the sensor when nitrogen (N2) is set to 100%. Therefore, in order to detect a specified gas (hydrogen), the output of the reference gas (nitrogen 100%) is measured in advance.

[0128] like Figure 4 As shown, in a state where the ambient temperature (temperature of the gas sensor 1) is fixed at 5°C, the power supply E of the power supply circuit 17 is set to a fixed voltage of 3.45V according to the output signal from the microcomputer 12 by driving the gas detection device 10 and applied to the thermal resistor element 2. The state is a state where power is supplied in a manner of heating the thermal resistor element 2. Furthermore, it is known that when overpower is supplied to the thermal resistor element 2 containing the thermistor composition, a thermal runaway phenomenon occurs.

[0129] like Figure 6 and Figure 7 As shown in FIG. 1 , when a voltage of 3.45 V is applied to the thermal resistor element 2 to supply power, the voltage applied to the sensor drops sharply after about 30 seconds (see FIG. 1 ). Figure 6 ), and the temperature of the sensor rises sharply (refer to Figure 7 ), and then shows a tendency to become a substantially constant value. The above-mentioned rapid change indicates that overpower is supplied to the thermal-sensitive resistor element 2 and the thermal-sensitive resistor element 2 is in a thermal runaway state.

[0130] Furthermore, in Figure 6 and Figure 7 In the graph, the difference between nitrogen (N2) 100%, hydrogen (H2) 1ppm, and hydrogen (H2) 2ppm is almost not shown, but this is because hydrogen (H2) is a very small amount and it is difficult to express it using the relationship with the curve. Figure 6 The voltage applied to the sensor in the range of 25 seconds to 35 seconds on the time axis is shown in FIG. Fig. 9 In addition, for clarity, Figure 8 The sensor output corresponding to the range of 20 seconds to 40 seconds on the time axis is shown in Fig.10 .

[0131] When a voltage of 3.45V is applied to the thermal resistor element 2 to supply power, the thermal resistor element 2 is energized and supplied with power, the thermal resistor element 2 is self-heated, and the gas molecule adsorbent 3 thermally coupled to the thermal resistor element 2 is heated. When the gas molecule adsorbent 3 is heated, the hydrogen (H2) adsorbed to the gas molecule adsorbent 3 is desorbed, and the temperature of the gas molecule adsorbent 3 changes according to the concentration. Therefore, the temperature of the thermal resistor element 2 (the temperature of the sensor) changes according to the concentration of hydrogen (H2), and the voltage applied to the sensor changes according to the concentration of hydrogen (H2) (refer to Fig. 9 ). In this way, the temperature of the sensor, the voltage applied to the sensor, and the sensor output change according to the concentration of hydrogen (H2), so the concentration of hydrogen (H2) can be detected.

[0132] Specifically, when power is supplied to the thermal resistor element 2, hydrogen (H2) adsorbed on the gas molecule adsorbing material 3 is desorbed and the temperature of the gas molecule adsorbing material 3 changes. The output corresponding to the concentration of hydrogen (H2) is calculated by the microcomputer 12 and can be output by the sensor (refer to Figure 8 ) pattern. A pattern of changes in sensor output corresponding to the concentration of hydrogen (H2) is pre-stored and saved in the storage mechanism of the microcomputer 12. The microcomputer 12 performs an operation of comparing the obtained sensor output pattern with the pre-stored and saved pattern, calculates the concentration of hydrogen (H2) as a detection output, and outputs it. In this way, the concentration of hydrogen (H2) can be detected.

[0133] In this way, by utilizing the thermal runaway phenomenon of the heat-sensitive resistor element 2 , a significant change in the sensor output can be obtained even when the concentration of hydrogen (H 2 ) is very small, thereby enabling detection of the concentration of hydrogen (H 2 ) which is very small.

[0134] The gas detection method includes: a step of maintaining the gas sensor 1 at a certain temperature; a heating step of setting the porous gas molecule adsorption material 3 to a heated state; and a detection step of detecting a specified gas by a change in the output of the thermal resistor element 2 caused by heating. In addition, in order to detect the specified gas, the output of the gas used as a reference is measured in advance. Furthermore, in the detection step, the result of the pre-measurement of the output of the gas used as a reference is compared with the measurement result of the output of the specified gas, thereby detecting the concentration of the specified gas. In addition, in the gas detection method, it also includes supplying overpower to the thermal resistor element 2 in the heating step to put the thermal resistor element 2 into a thermal runaway state, thereby supplying overpower to the thermal resistor element 2 to put the thermal resistor element 2 into a thermal runaway state.

[0135] Furthermore, based on the results of measurements under various conditions, it was confirmed that there is a tendency for thermal runaway of the thermal-sensitive resistor element 2 to occur more easily when the ambient temperature (temperature of the gas sensor 1) is low (below 10°C), and there is a tendency for thermal runaway of the thermal-sensitive resistor element 2 to occur more easily when the heat capacity of the thermal-sensitive resistor element 2 is small.

[0136] As described above, according to this embodiment, the lead portion 22 b is connected to the thermally sensitive resistor element 2 by welding, so that the heat capacity is small and the thermal responsiveness is accelerated, and the variation in the output characteristics of each gas sensor 1 can be suppressed, thereby improving the reliability.

[0137] In addition, the gas molecule adsorbing material 3 is formed on the surface of the heat-sensitive resistor element 2 by film formation, so that the heat capacity can be reduced. In addition, the thickness of the substrate 21 is formed to be 10 μm to 100 μm, and the diameter and thickness of the lead part 22b are small, so that the heat capacity can be reduced and the high-speed responsiveness can be promoted.

[0138] Furthermore, by utilizing the thermal runaway phenomenon of the heat-sensitive resistor element 2, the concentration of a trace amount of hydrogen (H 2 ) gas can be detected.

[0139] Next, refer to Fig.11 A second embodiment of the present invention will be described. Fig.11 2 is a cross-sectional view showing a gas sensor. Note that the same reference numerals are used for the same or corresponding parts as those in the first embodiment, and duplicate descriptions thereof will be omitted.

[0140] like Fig.11 As shown, the gas sensor 1 of the present embodiment is a sensor for detecting the concentration of gas in the environment, and includes a pair of thermosensitive resistor elements. That is, the detection thermosensitive resistor element 2 and the compensation thermosensitive resistor element 2a are provided and covered by an outer casing 5. Film formation is performed on the surface of the substrate 21 of the detection thermosensitive resistor element 2 and the compensation thermosensitive resistor element 2a to form a gas molecule adsorption material 3 and a gas molecule adsorption material 3a. The detection thermosensitive resistor element 2 and the compensation thermosensitive resistor element 2a are basically of the same structure, but the structure of the gas molecule adsorption material 3a provided in the compensation thermosensitive resistor element 2a is different. The gas molecule adsorption material 3a is a material having an adsorption property different from that of the porous gas molecule adsorption material 3, and a molecular sieve 3A of inactivated type A zeolite is used.

[0141] The deactivated molecular sieve 3A hardly adsorbs molecules, but has the same physical properties and thermal properties as the molecular sieve 3A provided in the detection thermally sensitive resistor element 2 , and has substantially the same heat capacity.

[0142] Next, refer to Fig.12 and Fig.13A third embodiment of the present invention will be described. Fig.12 This is a wiring diagram for characteristic detection of a gas detection device. Fig.13 It is a cross-sectional view showing a thermally sensitive resistor element. It is to be noted that the same reference numerals are given to the same or corresponding parts as those in the first embodiment, and duplicate descriptions thereof will be omitted.

[0143] like Fig.12 As shown, a heating or cooling element 8 as a temperature regulating element is connected to the gas detection device 10, and the heating or cooling element 8 heats or cools the gas sensor 1, that is, the heat-sensitive resistor element 2 and the gas molecule adsorption material 3 to keep them at a certain temperature. The heating or cooling element 8 is temperature-controlled by a temperature regulating circuit 9, so that the heating / cooling mode can be set arbitrarily. Representative heating or cooling elements can use resistors and thermoelectric elements.

[0144] As described above, when the heat-sensitive resistor element 2 is self-heated to perform heating control, the resistance value of the heat-sensitive resistor element 2 changes according to the temperature, so it is sometimes difficult to control. In this case, the heating / cooling control can be effectively functioned.

[0145] Fig.13 is the same as in the first embodiment Figure 2 The gas molecule adsorbent 3 is formed as a film on the protective insulating layer 24, and a heating or cooling element 8 is provided on the back side of the substrate 21. As the heating or cooling element 8, a thermistor may be used.

[0146] In addition, the heating or cooling element 8 can be applied not only to an element having a single heating or cooling function, but also to an element having both heating or cooling functions. Therefore, it can be specifically referred to as a heating and / or cooling element.

[0147] The gas sensors and gas detection devices of the above-mentioned embodiments are not limited to the gas to be detected, and can detect hydrogen (H2), water vapor (water molecules) (H2O), helium (He) and ammonia (NH3), etc., and can be installed in various devices such as medical equipment, automobiles, home appliances or OA equipment, food storage equipment, etc. The devices used are not particularly limited.

[0148] Furthermore, the present invention is not limited to the configuration of the above-mentioned embodiments, and various modifications can be made within the scope of the main purpose of the invention. In addition, the above-mentioned embodiment is provided as an example and is not intended to limit the scope of the invention. The novel embodiment can be implemented in various other ways, and various omissions, substitutions, and changes can be made. The embodiment or its modification is included in the scope or main purpose of the invention, and is also included in the invention described in the claims and its equivalent scope.

[0149] For example, porous metal complexes can be used as porous gas molecule adsorption materials. Porous metal complexes are a new concept of material group that transcends the boundaries of organic compounds and inorganic compounds by utilizing metal complexes. "Coordination polymers (especially porous coordination polymers (PCP)) with usable nano-sized spaces or metal organic frameworks (MOF)" have attracted much attention as new materials.

Claims

1. A gas sensor, characterized in that: include: A thermally sensitive resistor element having at least one pair of electrodes; A lead portion connected to the thermally sensitive resistor element in a state of being fused to the thermally sensitive resistor element without inclusions; as well as The porous gas molecule adsorbing material is thermally coupled to the thermally sensitive resistor element and desorbs the specified gas molecules by heating.

2. A gas sensor, characterized in that: include: Insulation parts; A heat-sensitive resistor element having at least one pair of electrodes, wherein the heat-sensitive resistor element is a thermistor, and the heat-sensitive resistor element is formed by film formation on one surface of the insulating component; A lead portion connected to the thermally sensitive resistor element in a state of being fused to the thermally sensitive resistor element without inclusions; as well as A porous gas molecule adsorption material is formed as a film on the other side of the insulating component and is thermally coupled to the thermal resistor element via the insulating component. The porous gas molecule adsorption material includes pores and only adsorbs molecules whose molecular diameters are smaller than the diameters of the pores. The porous gas molecule adsorption material desorbs the adsorbed molecules of the specified gas by heating.

3. A gas sensor, characterized in that: include: A substrate, wherein the substrate is formed using an insulating material; A conductive layer, wherein the conductive layer is a metal thin film formed on one side of the substrate; A heat-sensitive resistor element having at least one pair of electrodes, wherein the heat-sensitive resistor element is a thermistor, and the heat-sensitive resistor element is formed by film formation on the one side of the substrate; a protective insulating layer, the protective insulating layer covering the conductive layer and the thermally sensitive resistor element so that the conductive layer and the thermally sensitive resistor element are located between the substrate and the protective insulating layer; and A porous gas molecule adsorption material is formed on the surface of the protective insulating layer and the other side of the substrate, and is thermally coupled to the thermal resistor element via the protective insulating layer and the substrate. The porous gas molecule adsorption material includes pores and only adsorbs molecules whose molecular diameters are smaller than the diameters of the pores. The porous gas molecule adsorption material desorbs the adsorbed molecules of the specified gas by heating.

4. A gas sensor, characterized in that: include: A substrate, wherein the substrate is formed using an insulating material; A conductive layer, wherein the conductive layer is a metal thin film formed on one side of the substrate; A heat-sensitive resistor element having at least one pair of electrodes, wherein the heat-sensitive resistor element is a thermistor, and the heat-sensitive resistor element is formed by film formation on the one side of the substrate; a protective insulating layer, the protective insulating layer covering the conductive layer so that the conductive layer and the thermally sensitive resistor element are located between the substrate and the protective insulating layer; A porous gas molecule adsorption material is formed on the surface of the protective insulating layer and is thermally coupled to the thermally sensitive resistor element via the protective insulating layer, wherein the porous gas molecule adsorption material includes pores and only adsorbs molecules whose molecular diameters are smaller than the diameters of the pores, and the porous gas molecule adsorption material desorbs the adsorbed molecules of the specified gas by heating; and A heating and / or cooling element is disposed on the other side of the substrate and is used to keep the porous gas molecule adsorbing material at a certain temperature.

5. The gas sensor according to any one of claims 1 to 4, characterized in that: The thermal conductivity of the lead portion is 5W / m·k to 25W / m·k, and the cross-sectional area is 0.001mm 2 ~0.03mm 2 , and is formed of a material that can be welded.

6. The gas sensor according to any one of claims 1 to 4, characterized in that: The insulating component has a thickness of 10 μm to 100 μm.

7. The gas sensor according to any one of claims 1 to 4, characterized in that: The thickness of the film-forming porous gas molecule adsorbing material is 1 μm to 5 μm.

8. The gas sensor according to any one of claims 1 to 4, characterized in that: The lead portion is formed in a foil-like lead frame shape.

9. The gas sensor according to any one of claims 1 to 4, characterized in that: The porous gas molecule adsorbing material is zeolite or a porous metal complex.

10. The gas sensor according to claim 4, characterized in that: The heating and / or cooling elements are thermoelectric elements.

11. A gas detection device, characterized in that: include: The gas sensor according to claim 1 or 2; as well as A heating and / or cooling device is used to maintain the gas sensor at a certain temperature.

12. A gas detection method for a gas sensor according to any one of claims 1 to 10, characterized in that: include: The step of maintaining the gas sensor at a certain temperature; a heating step of placing the porous gas molecule adsorbent in a heated state so that the porous gas molecule adsorbent desorbs the adsorbed molecules of the designated gas; as well as The detection step detects the specified gas by a change in the output of the thermally sensitive resistor element caused by the heating.

13. The gas detection method according to claim 12, characterized in that: In order to detect the specified gas, the output of a reference gas is measured in advance.

14. The gas detection method according to claim 12, characterized in that: In the detection step, the concentration of the designated gas is detected by comparing the result of measuring the output of the reference gas in advance with the result of measuring the output of the designated gas.

15. The gas detection method according to claim 12, characterized in that: In the heating step, overpower is supplied to the heat-sensitive resistance element to put the heat-sensitive resistance element into a thermal runaway state.

16. The gas detection method according to any one of claims 12 to 15, characterized in that: The certain temperature is below 10°C.

17. An electrical equipment, characterized in that: include: The gas sensor according to any one of claims 1 to 10; or The gas detection device according to claim 11.

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