Sensor module, gas sensor, control device, control method and control program

Abstract

To provide a technique capable of appropriately identifying a percentage content of at least one kind of gas included in a mixture gas without being influenced by an aging deterioration of a temperature sensor.SOLUTION: A sensor module (1) includes: a heater (H1); a first temperature sensor (Th1) configured to measure a first temperature of a mixture gas at a heatable first location; a second temperature sensor (Th2) configured to measure a second temperature (T0) of the mixture gas at a second location not to be heated; and a control device (100). The control device (100) calculates the first temperature when the first temperature sensor (Th1) is heated, according to an electrical resistance of the first temperature sensor (Th1) when not heated and an electrical resistance of the first temperature sensor (Th1) when heated, a temperature resistance factor of the first temperature sensor (Th1) calculated according to the electrical resistance of the first temperature sensor (Th1) when not heated and the second temperature calculated according to an electrical resistance of the second temperature sensor (Th2).SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present disclosure relates to a sensor module, a gas sensor, a control device, a control method, and a control program for specifying the content rate of at least one type of gas contained in a mixed gas.

Background Art

[0002] Conventionally, a sensor for specifying the content rate of at least one type of gas contained in a mixed gas is known. For example, Japanese Unexamined Patent Application Publication No. 2022-183481 (Patent Document 1) discloses a gas sensor that specifies the content rate of a gas contained in a mixed gas by utilizing the fact that a temperature sensor made of platinum is heated by a heater.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

[0004] In the correction method using a compensation sensor, since the compensation sensor has the same configuration as the temperature sensor, it is assumed that the degree of deterioration of the temperature sensor and the compensation sensor is the same, and a method is adopted in which the detection result of the temperature sensor is corrected using the degree of change in the detection result of the compensation sensor. However, there are individual differences in the characteristics of each of the compensation sensor and the temperature sensor, so the degree of deterioration may differ for each individual, and it is not possible to suppress the influence of the secular deterioration of the temperature sensor, and there is a risk that the content rate of at least one type of gas contained in the mixed gas cannot be specified appropriately.

[0005] The present disclosure has been made in view of the problems of the prior art as described above, and provides a technique for appropriately specifying the content rate of at least one type of gas contained in a mixed gas without being affected by the secular deterioration of a temperature sensor.

[0006] The sensor module of the present disclosure is a sensor module that specifies the content rate of at least one type of gas contained in a mixed gas, and includes a heat conduction type heater that generates heat in response to supplied power, and is disposed at a first position that can be heated by the heater, and measures the first temperature of the mixed gas at the first position by changing the electrical resistance in response to a temperature change. A first temperature sensor, a second temperature sensor disposed at a second position not heated by the heater, and measuring the second temperature of the mixed gas at the second position by changing the electrical resistance in response to a temperature change, and a control device. The control device calculates the temperature resistance coefficient of the first temperature sensor based on the electrical resistance of the first temperature sensor when not heated by the heater, calculates the second temperature based on the electrical resistance of the second temperature sensor, and calculates the electrical resistance of the first temperature sensor when not heated by the heater, the electrical resistance of the first temperature sensor when heated by the heater, the temperature resistance coefficient of the first temperature sensor, and the second temperature. Based on this, the first temperature when the first temperature sensor is heated by the heater is calculated.

[0007] The control device of the present disclosure is a control device that controls a gas sensor that specifies the content rate of at least one type of gas contained in a mixed gas. The gas sensor includes a heat conduction type heater that generates heat in response to supplied power, a first temperature sensor that is disposed at a first position that can be heated by the heater and measures the first temperature of the mixed gas at the first position by changing its electrical resistance in response to a temperature change, and a second temperature sensor that is disposed at a second position that is not heated by the heater and measures the second temperature of the mixed gas at the second position by changing its electrical resistance in response to a temperature change. The control device includes a gas sensor interface that acquires the electrical resistance of the first temperature sensor and the electrical resistance of the second temperature sensor, a temperature resistance coefficient of the first temperature sensor calculated using the electrical resistance of the first temperature sensor when not heated by the heater, a second temperature calculated using the electrical resistance of the second temperature sensor, the electrical resistance of the first temperature sensor when not heated by the heater, and an arithmetic device that calculates the first temperature when the first temperature sensor is heated by the heater based on the electrical resistance of the first temperature sensor when heated by the heater.

[0008] The control method of the present disclosure is a control method for controlling a gas sensor that specifies the content rate of at least one type of gas contained in a mixed gas. The gas sensor includes a heat conduction type heater that generates heat in response to supplied power, a first temperature sensor that is disposed at a first position that can be heated by the heater and measures the first temperature of the mixed gas at the first position by changing its electrical resistance in response to a temperature change, and a second temperature sensor that is disposed at a second position that is not heated by the heater and measures the second temperature of the mixed gas at the second position by changing its electrical resistance in response to a temperature change. The control method includes, as processes executed by a computer, a step of calculating a temperature-resistance coefficient of the first temperature sensor based on the electrical resistance of the first temperature sensor when the heater is not heating, a step of calculating the second temperature based on the electrical resistance of the second temperature sensor, and a step of calculating the first temperature when the first temperature sensor is heated by the heater based on the electrical resistance of the first temperature sensor when the heater is not heating, the electrical resistance of the first temperature sensor when the heater is heating, the temperature-resistance coefficient of the first temperature sensor, and the second temperature.

[0009] The control program of the present disclosure is a control program for controlling a gas sensor that specifies the content rate of at least one type of gas contained in a mixed gas. The gas sensor includes a heat conduction type heater that generates heat in response to supplied power, a first temperature sensor that is disposed at a first position that can be heated by the heater and measures the first temperature of the mixed gas at the first position by changing its electrical resistance in response to a temperature change, and a second temperature sensor that is disposed at a second position that is not heated by the heater and measures the second temperature of the mixed gas at the second position by changing its electrical resistance in response to a temperature change. The control program causes a computer to execute a step of calculating a temperature resistance coefficient of the first temperature sensor based on the electrical resistance of the first temperature sensor when the first temperature sensor is not heated by the heater, and a step of calculating the second temperature based on the electrical resistance of the second temperature sensor, and calculating the first temperature when the first temperature sensor is heated by the heater based on the electrical resistance of the first temperature sensor when the first temperature sensor is not heated by the heater, the electrical resistance of the first temperature sensor when the first temperature sensor is heated by the heater, the temperature resistance coefficient of the first temperature sensor, and the second temperature.

Brief Description of the Drawings

[0010]

Figure 1

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Figure 11

Figure 12

[0011] [Detailed Description] [Embodiment 1] Embodiment 1 of the present disclosure will be described in detail with reference to the drawings. Note that the same or corresponding parts in the drawings are denoted by the same reference numerals and their descriptions will not be repeated.

[0012] [Configuration of Sensor Module] With reference to FIGS. 1 to 6, the configuration of the sensor module 1 according to Embodiment 1 will be described. FIG. 1 is a diagram for explaining the configuration of the sensor module 1 according to Embodiment 1. As shown in FIG. 1, the sensor module 1 according to Embodiment 1 includes a gas sensor 10 and a control device 100. The gas sensor 10 includes a heater H1, a temperature sensor Th1, and a temperature sensor Th2. Note that the temperature sensor Th1 may correspond to the "first temperature sensor" in the present disclosure. The temperature sensor Th2 may correspond to the "second temperature sensor" in the present disclosure.

[0013] The gas sensor 10 is a chip-type gas sensor that has a micro heater using MEMS (Micro Electro Mechanical Systems) technology and detects a gas to be detected such as hydrogen. The heater H1 is a heat conduction type heater that generates heat according to the supplied power. The temperature sensors Th1 and Th2 are installed in the same mixed gas and are configured to be able to detect the temperature of the mixed gas. Hereinafter, the gas in the space where the temperature sensors Th1 and Th2 are installed may be referred to as the "atmosphere".

[0014] Hereinafter, with reference to FIG. 2, the appearance of the gas sensor 10 will be described. FIG. 2 is a diagram for explaining an external perspective view of the gas sensor 10 according to Embodiment 1. The gas sensor 10 has a silicon substrate Sb1, a thin film layer 19, and a thin film layer 11. The thin film layer 19 is provided on the silicon substrate Sb1. The thin film layer 11 is provided on the thin film layer 19. In FIG. 2 and the following description, the normal direction of the thin film layer 11 is defined as the Z-axis direction, and the directions orthogonal thereto (in-plane directions of the thin film layer 11) are defined as the X-axis and Y-axis directions.

[0015] The temperature sensor Th1 includes an element E1 made of platinum and is disposed on the thin film layer 11. Similarly, the temperature sensor Th2 includes an element E2 made of platinum and is disposed on the thin film layer 11.

[0016] FIG. 3 is a cross-sectional view of the gas sensor 10 taken along the line A-A shown in FIG. 2. FIG. 3 shows the silicon substrate Sb1, the thin film layers 11 and 19, the element E1 functioning as the temperature sensor Th1, and the heater H1. Note that the silicon substrate Sb1 may correspond to the "support substrate" in the present disclosure. Also, the thin film layer 11 may correspond to the "specific layer" in the present disclosure.

[0017] An open cavity Cv1 is formed on the back surface of the silicon substrate Sb1. The thickness D0 in the Z-axis direction between the thin film layer 19 and the thin film layer 11 is, for example, about 2.4 μm. The base materials of the thin film layers 11 and 19 contain silicon dioxide (SiO2).

[0018] A heater H1 is provided in the thin film layer 11. The heater H1 has a metal oxide Mh1 and a metal Ph1. The metal Ph1 is composed of platinum. An element E1 is provided as a temperature sensor Th1 on the thin film layer 11. The element E1 has a metal oxide M1 and a metal P1 provided on the metal oxide M1. The metal P1 is composed of platinum. The metal oxide M1 functions as a barrier film between the thin film layer 11 and the metal P1, and contains at least one of titanium oxide (TiO2), chromium oxide (Cr2O3), tantalum pentoxide (Ta2O5), and an oxygen-deficient metal oxide.

[0019] In the heat conduction type temperature sensor Th1 configured as described above, the heater H1 generates heat according to the electric power supplied from the control device 100 (hereinafter also referred to as "heater electric power"), and the thin film layer 11 is heated. The element E1 provided on the thin film layer 11 is exposed in the mixed gas. Direct heat exchange occurs between the element E1 and the mixed gas. The control device 100 specifies the temperature of the mixed gas around the element E1 by acquiring the electric resistance of the element E1. Thereby, the element E1 functions as a temperature sensor Th1. Hereinafter, the electric resistance of the element E1 is also referred to as "the electric resistance of the temperature sensor Th1".

[0020] The temperature sensor Th1 is arranged at a position where it can be heated by the heater H1. In the example of Embodiment 1, the temperature sensor Th1 is arranged at a position overlapping the heater H1 when viewed in plan with respect to the Z-axis. The position where the temperature sensor Th1 is arranged may correspond to the "first position" in the present disclosure. The temperature of the mixed gas detected by the temperature sensor Th1 may correspond to the "first temperature" in the present disclosure. Hereinafter, the temperature of the mixed gas around the temperature sensor Th1 detected based on the electric resistance of the temperature sensor Th1 is simply referred to as the "detection value of the temperature sensor Th1".

[0021] FIG. 4 is a cross-sectional view of the gas sensor 10 taken along the line B-B shown in FIG. 2. FIG. 4 shows a silicon substrate Sb1, thin film layers 11 and 19, and an element E2 that functions as a temperature sensor Th2. The element E2 has a metal oxide M2 and a metal P2 provided on the metal oxide M2. The metal oxide M2 has the same configuration as the metal oxide M1 and functions as a barrier film between the thin film layer 11 and the metal P2. The metal P2 is made of platinum, similarly to the metal P1.

[0022] The element E2 provided on the thin film layer 11 is exposed to the air-fuel mixture. Direct heat exchange occurs between the element E2 and the air-fuel mixture. The control device 100 detects the temperature of the element E2 as the temperature of the air-fuel mixture by acquiring the electrical resistance of the element E2. Thereby, the element E2 functions as a temperature sensor Th2. Hereinafter, the electrical resistance of the element E2 is also referred to as the "electrical resistance of the temperature sensor Th2".

[0023] The temperature sensor Th2 is arranged at a position that is not heated by the heater H1. In the example of Embodiment 1, the temperature sensor Th1 is arranged at a position shifted from the position overlapping the heater H1 when viewed in plan on the Z-axis. The position where the temperature sensor Th2 is arranged may correspond to the "second position" in the present disclosure. The temperature of the air-fuel mixture detected by the temperature sensor Th2 may correspond to the "second temperature" in the present disclosure. Hereinafter, the temperature of the air-fuel mixture around the temperature sensor Th2 detected based on the electrical resistance of the temperature sensor Th2 is simply referred to as the "detection value of the temperature sensor Th2".

[0024] The temperature of the air-fuel mixture detected by the temperature sensors Th1 and Th2 changes according to the thermal conductivity of the gas present in the air-fuel mixture where the temperature sensors Th1 and Th2 are disposed. Here, with reference to FIGS. 5 and 6, the thermal conductivity of each of a plurality of types of gases will be described. Hydrogen, air, and nitrogen have different thermal conductivities from each other. FIG. 5 is a diagram showing an example of the thermal conductivity of each of a plurality of types of gases. As shown in FIG. 5, when the temperature in the air-fuel mixture containing each gas is 0° C., the thermal conductivity of hydrogen is the highest, and then, in descending order of thermal conductivity, air and nitrogen are listed. The air is standard air, for example, the air at the time of shipment of the temperature sensors Th1 and Th2.

[0025] Furthermore, for each of hydrogen, air, and nitrogen, the thermal conductivity of each gas changes according to the temperature change of the air-fuel mixture. FIG. 6 is a diagram showing an example of the thermal conductivity with respect to the temperature in each of a plurality of types of gases. In the graph shown in FIG. 6, for simplicity of illustration, the thermal conductivity of hydrogen is converted to 1 / 10.

[0026] As shown in FIG. 6, as the temperature in the air-fuel mixture changes between 200K and 800K, the thermal conductivity of each gas changes. Specifically, the higher the temperature in the air-fuel mixture, the higher the thermal conductivity of each gas. Furthermore, the thermal conductivity with respect to the temperature in the air-fuel mixture is the highest for hydrogen, and then in descending order, air and nitrogen. Thus, since the thermal conductivity differs according to the type of gas present in the air-fuel mixture where the temperature sensor Th1 is disposed, the temperature of the air-fuel mixture around the temperature sensors Th1 and Th2 differs according to the type (thermal conductivity) of the gas present in the air-fuel mixture.

[0027] For example, the thermal conductivity of hydrogen is higher than the thermal conductivity of each of air and nitrogen. For this reason, if the atmosphere around the temperature sensors Th1 and Th2 is composed only of hydrogen, heat from the heater H1 more easily escapes into the atmosphere around the temperature sensors Th1 and Th2 than when the atmosphere is composed only of air or when the atmosphere is composed only of nitrogen, and the temperature of the air-fuel mixture detected by the temperature sensor Th1 becomes lower.

[0028] In contrast, the thermal conductivity of each of air and nitrogen is smaller than that of hydrogen. Therefore, when the atmosphere is composed only of air, the heat of the temperature sensor Th1 is less likely to escape into the surrounding atmosphere than when the atmosphere is composed only of hydrogen, and the temperature of the air-fuel mixture detected by the temperature sensor Th1 becomes higher. Similarly, when the atmosphere is composed only of nitrogen, the heat of the temperature sensor Th1 is less likely to escape into the surrounding atmosphere than when the atmosphere is composed only of hydrogen, and the temperature of the air-fuel mixture detected by the temperature sensor Th1 becomes higher.

[0029] That is, the temperature of the temperature sensor Th1 changes according to the type (thermal conductivity) of the gas present in the air-fuel mixture in which the temperature sensor Th1 is disposed, and the electrical resistance of the platinum constituting the element E1 changes according to the temperature of the temperature sensor Th1. Utilizing such a phenomenon, the control device 100 can acquire the electrical resistance of the platinum of the element E1 and detect the content rate of a specific gas present in the air-fuel mixture based on the acquired electrical resistance.

[0030] In the present embodiment, the control device 100 specifies the temperature of the temperature sensor Th1 based on the detected electrical resistance of the platinum, and detects the content rate of the specific gas based on the specified temperature of the temperature sensor Th1. Hereinafter, the electrical resistance of the platinum in the element E1 may be referred to as the "electrical resistance of the temperature sensor Th1".

[0031] Returning to FIG. 1, the control device 100 in the example of the present embodiment acquires the electrical resistance of the element E1 and specifies at least the content rate of hydrogen present in the atmosphere in which the temperature sensor Th1 is disposed. The control device 100 is an information processing device such as, for example, a notebook or desktop PC, a smartphone, a tablet terminal, an in-vehicle ECU (Engine Control Unit), or a PLC (Programmable Logic Controller) of production equipment.

[0032] The control device 100 mainly includes an arithmetic unit 101, a memory 102, a storage device 103, a communication device 104, a display interface 105, a peripheral device interface 106, a storage medium interface 107, and a gas sensor interface 108.

[0033] The arithmetic unit 101 is an arithmetic entity (computer) that executes various processes by executing various programs. The arithmetic unit 101 is composed of a processor such as a CPU (Central Processing Unit) or an MPU (Micro-Processing Unit), for example. Note that a processor, which is an example of the arithmetic unit 101, has a function of executing various processes by executing a program, but some or all of these functions may be implemented using a dedicated hardware circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array).

[0034] The "processor" is not limited to a narrow sense processor that executes processing in a stored program manner such as a CPU or an MPU, and may include a hardwired circuit such as an ASIC or an FPGA. Therefore, the "processor", which is an example of the arithmetic unit 101, can also be read as a processing circuitry whose processing is defined in advance by computer-readable code and / or a hardwired circuit. Note that the arithmetic unit 101 may be composed of one chip or a plurality of chips. Furthermore, some functions of the arithmetic unit 101 may be provided in a server device (for example, a cloud-type server device) not shown in the figure.

[0035] Memory 102 includes a volatile memory area (e.g., a working area) that temporarily stores program codes, work memories, etc. when the arithmetic unit 101 executes various programs. Examples of memory 102 include volatile memories such as DRAM (Dynamic Random Access Memory) and SRAM (Static Random Access Memory), or non-volatile memories such as ROM (Read Only Memory) and flash memory.

[0036] Storage device 103 stores various programs or various data executed by arithmetic unit 101. Storage device 103 may be one or more non-transitory computer readable media, or may be one or more computer readable storage media. Examples of storage device 103 include HDD (Hard Disk Drive) and SSD (Solid State Drive). In the control device 100 according to Embodiment 1, storage device 103 stores control program 120 and thermal conductivity data 130.

[0037] As described above, control program 120 defines a process of calculating the temperature (T) of the air-fuel mixture detected by temperature sensor Th1 when heated, based on the electrical resistance acquired by arithmetic unit 101 from temperature sensors Th1 and Th2, and a process for detecting the hydrogen content present in the air-fuel mixture. Thermal conductivity data 130 is data regarding the thermal conductivity of each of a plurality of types of gases contained in the air-fuel mixture, and includes data indicating the thermal conductivity with respect to temperature in each gas as shown in FIG. 5.

[0038] Communication device 104 transmits and receives data to and from an external device (not shown) via wired communication or wireless communication.

[0039] The display interface 105 is an interface for connecting the display 51. The display interface 105 realizes the input and output of data between the control device 100 and the display 51. For example, the display interface 105 outputs various image data to the display 51 according to the control of the arithmetic unit 101. The display 51 displays the image data acquired from the display interface 105.

[0040] The peripheral device interface 106 is an interface for connecting peripheral devices 60 such as a keyboard or a mouse. The peripheral device interface 106 realizes the input and output of data between the control device 100 and the peripheral device 60. For example, the peripheral device interface 106 acquires various data such as the control program 120 or the thermal conductivity data 130 input by the user using the peripheral device 60.

[0041] The storage medium interface 107 is an interface for connecting a storage medium 70 such as a removable disk or a USB (Universal Serial Bus) memory. The storage medium interface 107 reads out various data such as programs or data stored in the storage medium 70, or writes out various data to the storage medium 70. For example, the storage medium interface 107 reads out various data such as the control program 120 or the thermal conductivity data 130 stored in the storage medium 70 from the storage medium 70, or writes out various data such as the control program 120 or the thermal conductivity data 130 stored in the storage device 103 to the storage medium 70.

[0042] The gas sensor interface 108 is an interface for connecting the gas sensor 10. The gas sensor interface 108 acquires the electrical resistances of the elements E1 and E2. Further, the gas sensor interface 108 supplies heater power to the temperature sensors Th1 and Th2 according to the control of the arithmetic unit 101. Note that the gas sensor interface 108 may be divided into different configurations as an interface for acquiring the electrical resistances of the elements E1 and E2 from the gas sensor 10 and an interface for supplying heater power to the gas sensor 10.

[0043] [Regarding the Aging Deterioration of Platinum] The electrical resistance of platinum is proportional to the temperature of platinum. Therefore, in a general temperature sensor using platinum, a graph showing the relationship between the electrical resistance of platinum and the temperature of platinum is predetermined based on the characteristics at the time of shipment of the temperature sensor, and the temperature of platinum can be directly obtained from the electrical resistance of platinum using the graph. However, since the characteristics of the temperature sensor change due to aging deterioration, if the graph showing the relationship between the electrical resistance of platinum and the temperature of platinum predetermined at the time of shipment of the temperature sensor is continuously used, an error may occur in the detection result.

[0044] To correct the influence of this error, it is conceivable to use the compensation sensor described above. However, even if a compensation sensor is used, there are individual differences, so the degree of deterioration of the temperature sensor and the compensation sensor is not necessarily the same, and there may be cases where the influence of the aging deterioration of the temperature sensor cannot be appropriately corrected. Instead of directly calculating the detection value of the temperature sensor Th1 from the electrical resistance of the element E1 composed of platinum, if the following formula is used, the detection value of the temperature sensor Th1 when it is heated can be specified based on the change amount of the electrical resistance of the element E1 before and after heating by the heater H1.

[0045] [Equation]

[0046] In the formula, "T" represents the detected value of the temperature sensor Th1 when the temperature sensor Th1 is being heated by the heater H1. "R" in the formula represents the electrical resistance of the temperature sensor Th1 when the temperature sensor Th1 is being heated by the heater H1. "R0" in the formula represents the electrical resistance of the temperature sensor Th1 when the temperature sensor Th1 is not being heated by the heater H1. "α" in the formula represents the temperature coefficient of resistance of the temperature sensor Th1. "T0" in the formula represents the detected value of the temperature sensor Th2.

[0047] The temperature coefficient of resistance α indicates the ratio of the change in the electrical resistance of the element E1 when the temperature of the element E1 increases by a predetermined temperature from a certain temperature. The temperature coefficient of resistance α of the element E1 can be measured at the time of shipment of the temperature sensor Th1 but changes due to aging deterioration. Therefore, when using the above formula, it is necessary to obtain the temperature coefficient of resistance α after aging deterioration when determining the value of the temperature coefficient of resistance α.

[0048] On the other hand, regarding the electrical resistance R and the electrical resistance R0, in the gas sensor 10, since the electrical resistance of the element E1 is acquired every time the measurement is made, the electrical resistance R and the electrical resistance R0 after being affected by aging deterioration can be acquired. There is no need to consider the influence of aging deterioration when determining the value of the electrical resistance R and the value of the electrical resistance R0 in the formula.

[0049] In a state where the heater H1 is not being heated, the temperature of the air-fuel mixture around the temperature sensors Th1 and Th2 arranged in the same atmosphere is substantially the same. Therefore, in the present embodiment, the temperature T0, which is the detected value of the temperature sensor Th2, is used as the detected value of the temperature sensor Th1 when it is not being heated. Thereby, the gas sensor 10 can acquire the temperature of the air-fuel mixture around the temperature sensor Th1 when it is not being heated by the heater H1 without being affected by the aging deterioration of the temperature sensor Th1.

[0050] Furthermore, the inventor of the present disclosure has found a method for calculating the temperature coefficient of resistance α after being affected by aging deterioration based on the electrical resistance R0. Hereinafter, based on FIGS. 7 and 8, a method for calculating the temperature coefficient of resistance α based on the electrical resistance R0 will be described.

[0051] FIG. 7 is a diagram showing the relationship between the annealing time, the specific resistance, and the temperature coefficient of resistance α in platinum. The annealing time shown on the horizontal axis means the integrated time during which the annealing treatment is performed on platinum. The specific resistance (Ω·m), which is the electrical resistance of platinum per unit cross-sectional area, is shown on the left vertical axis.

[0052] The black circles shown in FIG. 7 indicate the values of the temperature coefficient of resistance α of platinum. That is, as the annealing time increases, the temperature coefficient of resistance α of platinum increases. The white circles shown in FIG. 7 indicate the values of the specific resistance of platinum. That is, as the annealing time increases, the specific resistance of platinum decreases. As shown in FIG. 7, the change rate of the temperature coefficient of resistance α of platinum and the change rate of the specific resistance of platinum with respect to the degree of increase in the annealing time have a correlation.

[0053] FIG. 8 is a diagram showing the relationship between the specific resistance and the temperature coefficient of resistance α in FIG. 7. As shown in FIG. 8, the specific resistance and the temperature coefficient of resistance α have a proportional relationship. That is, if the specific resistance of the element E1 is calculated from the electrical resistance R0 of the element E1 when it is not heated, the temperature coefficient of resistance α of the element E1 after being affected by aging can be obtained from the specific resistance of the element E1.

[0054] In the storage device 103 in the first embodiment, the graph or relational expression in FIG. 8 showing the proportional relationship between the temperature coefficient of resistance α of the temperature sensor Th1 and the electrical resistance R0 of the temperature sensor Th1 when it is not heated by the heater H1 is stored in advance. The control device 100 can obtain the temperature coefficient of resistance α from the electrical resistance R0 using the graph or relational expression.

[0055] As a result, the gas sensor 10 of the present embodiment can acquire all the elements (R, R0, α, T0) for obtaining T in the above formula as the values after being affected by aging deterioration. That is, the gas sensor 10 of the present embodiment can calculate the detection value of the temperature sensor Th1 after the influence of aging deterioration is considered, and can appropriately specify the content rate of at least one kind of gas contained in the air-fuel mixture without being affected by the aging deterioration of the temperature sensor Th1.

[0056] [Processing procedure] FIG. 9 is a flowchart showing a processing procedure for calculating the detection value of the temperature sensor Th1. The processing in FIG. 9 is realized by the control program 120 being executed by the arithmetic unit 101.

[0057] The arithmetic unit 101 starts executing the flowchart shown in FIG. 9, for example, based on an instruction from the user. When the heater H1 is being driven at the start of executing the flowchart shown in FIG. 9, the arithmetic unit 101 stops the driving of the heater H1, and after a predetermined period has elapsed, executes the process of step S101.

[0058] The arithmetic unit 101 acquires the electrical resistance R0 of the element E1 when it is not heated (step S101). The arithmetic unit 101 calculates the temperature coefficient of resistance α of the element E1 based on the electrical resistance R0 of the element E1 using the relationship between the specific resistance of platinum and the temperature coefficient of resistance α shown in FIG. 8 (step S101). The arithmetic unit 101 acquires the temperature T0, which is the detection value of the temperature sensor Th2, from the electrical resistance of the element E2 (step S102).

[0059] The arithmetic unit 101 drives the heater H1 (step S103). The arithmetic unit 101 determines whether or not a predetermined period has elapsed (step S104). If the predetermined period has not elapsed (NO in step S104), the arithmetic unit 101 repeats the process of step S104. That is, the arithmetic unit 101 secures a period during which the element E1 is sufficiently heated by the heater H1.

[0060] When the specified period has elapsed (YES in step S104), the arithmetic unit 101 acquires the electrical resistance R of the element E1 when it is heated (step S105). The arithmetic unit 101 calculates the temperature T, which is the detected value of the temperature sensor Th1, using the above formula (step S106). As a result, the control device 100 can calculate the detected value of the temperature sensor Th1 after considering the influence of aging deterioration, and can appropriately specify the content rate of at least one type of gas contained in the mixed gas without being affected by the aging deterioration of the temperature sensor Th1.

[0061] [Embodiment 2] In Embodiment 1, an example in which the element E1 and the element E2 are arranged on the thin film layer 11 has been described. In Embodiment 2, an example in which the slit SL1 is formed on the thin film layer 11 will be described. Note that in Embodiment 2, the description of the configuration overlapping with that of Embodiment 1 will not be repeated.

[0062] FIG. 10 is a diagram for explaining an external perspective view of the gas sensor 10A according to Embodiment 2. As shown in FIG. 10, a slit SL1 is formed between the element E1 and the element E2 in the Y-axis direction. The slit SL1 is a groove having a depth in the Z-axis direction formed in the thin film layer 11.

[0063] Thereby, the isolation between the element E2 and the heater H1 is improved. That is, in Embodiment 2, the degree of influence of heating of the heater H1 on the element E2 can be reduced by the slit SL1. Note that the depth of the slit SL1 in the Z-axis direction may reach the thin film layer 19 through the thin film layer 11. Also in Embodiment 2, similar to Embodiment 1, the detected value of the temperature sensor Th1 after considering the influence of aging deterioration can be calculated, and the content rate of at least one type of gas contained in the mixed gas can be appropriately specified without being affected by the aging deterioration of the temperature sensor Th1.

[0064] [Embodiment 3] In Embodiment 1, an example in which element E1 and element E2 are arranged on thin film layer 11 was described. In Embodiment 3, an example in which temperature sensor Th2 is configured as a separate body from gas sensor 10B having temperature sensor Th1 will be described. Note that in Embodiment 2, the description of the configuration overlapping with that of Embodiment 1 will not be repeated.

[0065] FIG. 11 is a diagram for explaining the configuration of sensor module 1B according to Embodiment 3. FIG. 12 is a diagram for explaining an external perspective view of gas sensor 10B according to Embodiment 3.

[0066] As shown in FIG. 11, in Embodiment 3, temperature sensor Th2 is provided as a temperature sensor separate from gas sensor 10. Temperature sensor Th2 is provided to acquire temperature T0. Temperature T0 indicates the temperature of the air-fuel mixture around temperature sensor Th1 before being heated. Therefore, temperature sensor Th2 may be a temperature sensor arranged in the same space as temperature sensor Th1, and it is not necessary to be mounted on gas sensor 10 in the same manner as temperature sensor Th1.

[0067] In Embodiment 3, temperature sensor Th2 is a general temperature sensor capable of detecting the temperature of the air-fuel mixture around gas sensor 10B. Temperature sensor Th2 may be a general temperature sensor IC, or may include, for example, a thermistor. As shown in FIG. 12, gas sensor 10B in Embodiment 3 has only element E1 and does not have element E2. Thereby, in Embodiment 3, it is possible to miniaturize gas sensor 10B.

[0068] Also, in Embodiment 2 as well, similar to Embodiment 1, the detected value of temperature sensor Th1 after considering the influence of aging deterioration can be calculated, and the content rate of at least one type of gas contained in the air-fuel mixture can be appropriately specified without being affected by the aging deterioration of temperature sensor Th1.

[0069] [Appendix] (Item 1, Figures 1 to 8) The sensor module (1) of the present disclosure is a sensor module that specifies the content rate of at least one type of gas contained in the mixed gas. The sensor module (1) includes a heat conduction type heater (H1) that generates heat according to the supplied power, a first temperature sensor (Th1) that is disposed at a first position that can be heated by the heater (H1) and measures the first temperature of the mixed gas at the first position by changing the electrical resistance according to the temperature change, a second temperature sensor (Th2) that is disposed at a second position that is not heated by the heater and measures the second temperature (T0) of the mixed gas at the second position by changing the electrical resistance according to the temperature change, and a control device (100). The control device (100) calculates the temperature resistance coefficient (α) of the first temperature sensor (Th1) based on the electrical resistance (R0) of the first temperature sensor when the heater (H1) is not heating (Steps S100, S101), calculates the second temperature (T0) based on the electrical resistance of the second temperature sensor (Th2) (Step S102), and based on the electrical resistance (R0) of the first temperature sensor (Th1) when the heater (H1) is not heating, the electrical resistance (R) of the first temperature sensor (Th1) when the heater is heating, the temperature resistance coefficient (α) of the first temperature sensor (Th1), and the second temperature (T0), calculates the first temperature (T) when the first temperature sensor (Th1) is heated by the heater (H1) (Step S106).

[0070] (Item 2, Figure 8) In the sensor module (1) according to Item 1, the temperature resistance coefficient (α) of the first temperature sensor (Th1) is proportional to the electrical resistance (R0) of the first temperature sensor (Th1) when the heater (H1) is not heating.

[0071] (Item 3, Figure 9) In the sensor module (1) according to Item 1 or Item 2, the control device (100) calculates the first temperature (T) when the first temperature sensor (Th1) is heated by the heater (H1) according to the following formula (1),

[0072]

Equation

[0073] In the formula, R is the electrical resistance of the first temperature sensor (Th1) when the first temperature sensor (Th1) is heated by the heater (H1), R0 is the electrical resistance of the first temperature sensor (Th1) when the first temperature sensor (Th1) is not heated by the heater (H1), α is the temperature coefficient of resistance (α) of the first temperature sensor (Th1), T0 is the second temperature, T is the first temperature when the first temperature sensor (Th1) is heated by the heater (H1).

[0074] (Item 4, Figure 3) In the sensor module (1) according to any one of Items 1 to 3, the first temperature sensor (Th1) includes a first element (E1). The sensor module (1) further includes a support substrate (Sb1) and a specific layer (11) disposed above the support substrate. The first element (E1) is disposed on the specific layer (11).

[0075] (Item 5, Figure 4) In the sensor module (1) according to Item 4, the second temperature sensor (Th2) includes a second element (E2) different from the first element (E1). The second element (E2) is disposed on the specific layer (11).

[0076] (Item 6, Figure 10) In the sensor module (1) according to Item 5, the specific layer has a slit (SL1) between the first element (E1) and the second element (E2).

[0077] (Item 7, Figures 11, 12) In the sensor module (1) according to Item 4, the second temperature sensor (Th2) is configured as a separate body from the first temperature sensor (Th1).

[0078] (Item 8, FIGS. 7 to 9) The gas sensor (10) of the present disclosure is a gas sensor (10) that specifies the content rate of at least one type of gas contained in the air-fuel mixture, and is a heat conduction type heater (H1) that generates heat according to the supplied power, and is arranged at a first position that can be heated by the heater, and measures the first temperature of the air-fuel mixture at the first position by changing the electrical resistance according to the temperature change. A first temperature sensor (Th1), a second temperature sensor (Th2) arranged at a second position not heated by the heater, and measuring the second temperature (T0) of the air-fuel mixture at the second position by changing the electrical resistance according to the temperature change. The gas sensor uses the temperature resistance coefficient (α) of the first temperature sensor calculated using the electrical resistance (R0) of the first temperature sensor when the heater is not heated, the second temperature (T0) calculated using the electrical resistance of the second temperature sensor, and the heater. Based on the electrical resistance (R0) of the first temperature sensor when not heated and the electrical resistance (R) of the first temperature sensor when heated by the heater, the first temperature (T) when the first temperature sensor is heated by the heater can be calculated (step S106).

[0079] (Item 9, FIGS. 7 to 9) The control device (100) of the present disclosure is a control device (100) that controls a gas sensor (10) for specifying the content rate of at least one type of gas contained in the air-fuel mixture. The gas sensor includes a heat conduction type heater (H1) that generates heat in response to supplied power, a first temperature sensor (Th1) that is disposed at a first position that can be heated by the heater and measures the first temperature of the air-fuel mixture at the first position by changing its electrical resistance in response to a temperature change, and a second temperature sensor (Th2) that is disposed at a second position that is not heated by the heater and measures the second temperature (T0) of the air-fuel mixture at the second position by changing its electrical resistance in response to a temperature change. The control device includes a gas sensor interface (108) that acquires the electrical resistance of the first temperature sensor and the electrical resistance of the second temperature sensor, a temperature resistance coefficient (α) of the first temperature sensor calculated using the electrical resistance (R0) of the first temperature sensor when the heater is not heating, the second temperature (T0) calculated using the electrical resistance of the second temperature sensor, the electrical resistance (R0) of the first temperature sensor when the heater is not heating, and the electrical resistance (R) of the first temperature sensor when the heater is heating, and an arithmetic unit (101) that calculates the first temperature (T) when the first temperature sensor is heated by the heater based on these values (step S106).

[0080] (Item 10, FIGS. 7 to 9) The control method of the present disclosure is a control method for controlling a gas sensor (10) that specifies the content rate of at least one type of gas contained in a mixed gas. The gas sensor includes a heat conduction type heater (H1) that generates heat in response to supplied power, a first temperature sensor (Th1) disposed at a first position that can be heated by the heater and measures the first temperature of the mixed gas at the first position by changing its electrical resistance in response to a temperature change, and a second temperature sensor (Th2) disposed at a second position that is not heated by the heater and measures the second temperature (T0) of the mixed gas at the second position by changing its electrical resistance in response to a temperature change. The control method includes, as a process executed by a computer, a step (S100, S101) of calculating a temperature resistance coefficient (α) of the first temperature sensor based on the electrical resistance (R0) of the first temperature sensor when the heater is not heating, a step of calculating the second temperature (T0) based on the electrical resistance of the second temperature sensor (step S102), and a step (S106) of calculating the first temperature (T) when the first temperature sensor is heated by the heater based on the electrical resistance (R0) of the first temperature sensor when the heater is not heating, the electrical resistance (R) of the first temperature sensor when the heater is heating, the temperature resistance coefficient (α) of the first temperature sensor, and the second temperature (T0).

[0081] (Item 11, FIGS. 7 to 9) The control program of the present disclosure is a control program (120) for controlling a gas sensor (10) that specifies the content rate of at least one type of gas contained in the air-fuel mixture. The gas sensor includes a heat conduction type heater (H1) that generates heat in response to supplied power, a first temperature sensor (Th1) disposed at a first position that can be heated by the heater and measures the first temperature of the air-fuel mixture at the first position by changing its electrical resistance in response to a temperature change, and a second temperature sensor (Th2) disposed at a second position that is not heated by the heater and measures the second temperature (T0) of the air-fuel mixture at the second position by changing its electrical resistance in response to a temperature change. The control program causes a computer to execute steps (S100, S101) of calculating the temperature resistance coefficient (α) of the first temperature sensor based on the electrical resistance (R0) of the first temperature sensor when the heater is not heating, calculating the second temperature (T0) based on the electrical resistance of the second temperature sensor (step S102), and calculating the first temperature (T) when the first temperature sensor is heated by the heater based on the electrical resistance (R0) of the first temperature sensor when the heater is not heating, the electrical resistance (R) of the first temperature sensor when the heater is heating, the temperature resistance coefficient (α) of the first temperature sensor, and the second temperature (T0) (step S106).

[0082] As described above, the embodiments of the present disclosure have been described, but it is also possible to variously modify the above-described embodiments. Further, the scope of the present invention is not limited to the above-described embodiments. The scope of the present invention is indicated by the claims and is intended to include all modifications within the meaning and scope equivalent to the claims.

Description of Reference Numerals

[0083] 1,1B sensor module, 10, 10A, 10B gas sensors, 11, 19 thin film layers, 51 display, 60 peripheral devices, 70 storage medium, 100 control device, 101 arithmetic unit, 102 memory, 103 storage device, 104 communication device, 105 display interface, 06 peripheral device interface, 107 storage medium interface, 108 gas sensor interface, 120 control program, 130 thermal conductivity data, Cv1 cavity, D0 thickness, E1, E2 elements, H1 heater, Th1, Th2 temperature sensors, M1, M2, Mh1 metal oxides, P1, P2, Ph1 metals, SL1 slit, Sb1 silicon substrate.

Claims

1. A sensor module for specifying the content ratio of at least one type of gas contained in a mixed gas, a heat conduction type heater that generates heat in response to supplied power, a first temperature sensor disposed at a first position that can be heated by the heater and measuring the first temperature of the mixed gas at the first position by changing an electrical resistance in response to a temperature change, a second temperature sensor disposed at a second position not heated by the heater and measuring the second temperature of the mixed gas at the second position by changing an electrical resistance in response to a temperature change, and a control device, wherein the control device calculates a temperature-resistance coefficient of the first temperature sensor based on an electrical resistance of the first temperature sensor when not heated by the heater, calculates the second temperature based on an electrical resistance of the second temperature sensor, and calculates the first temperature when the first temperature sensor is heated by the heater based on the electrical resistance of the first temperature sensor when not heated by the heater, the electrical resistance of the first temperature sensor when heated by the heater, the temperature-resistance coefficient of the first temperature sensor, and the second temperature. A sensor module.

2. The sensor module according to claim 1, wherein the temperature-resistance coefficient of the first temperature sensor is proportional to the electrical resistance of the first temperature sensor when not heated by the heater.

3. The control device calculates the first temperature when the first temperature sensor is heated by the heater according to the following formula (1), 【Number 1】 wherein R is the electrical resistance of the first temperature sensor when the first temperature sensor is heated by the heater, R0 is the electrical resistance of the first temperature sensor when the first temperature sensor is not heated by the heater, α is the temperature-resistance coefficient of the first temperature sensor, T0 is the second temperature, and T is the first temperature when the first temperature sensor is heated by the heater. The sensor module according to claim 1 or claim 2.

4. The first temperature sensor includes a first element, and the sensor module further includes a support substrate, and a specific layer disposed above the support substrate, wherein the first element is disposed on the specific layer. The sensor module according to claim 1.

5. The second temperature sensor includes a second element different from the first element, The second element is disposed on the specific layer, and the sensor module according to claim 4.

6. The specific layer has a slit between the first element and the second element, and the sensor module according to claim 5.

7. The second temperature sensor is configured separately from the first temperature sensor, and the sensor module according to claim 4.

8. A gas sensor for specifying the content rate of at least one kind of gas contained in a mixed gas, A heat conduction type heater that generates heat according to supplied power, A first temperature sensor disposed at a first position that can be heated by the heater, and measuring the first temperature of the mixed gas at the first position by changing an electrical resistance according to a temperature change, A second temperature sensor disposed at a second position that is not heated by the heater, and measuring the second temperature of the mixed gas at the second position by changing an electrical resistance according to a temperature change, The gas sensor is configured to calculate the first temperature when the first temperature sensor is heated by the heater based on the temperature resistance coefficient of the first temperature sensor calculated using the electrical resistance of the first temperature sensor when the heater is not heated, the second temperature calculated using the electrical resistance of the second temperature sensor, the electrical resistance of the first temperature sensor when the heater is not heated, and the electrical resistance of the first temperature sensor when the heater is heated. Gas sensor.

9. A control device for controlling a gas sensor for specifying the content rate of at least one kind of gas contained in a mixed gas, The gas sensor is A heat conduction type heater that generates heat according to supplied power, A first temperature sensor disposed at a first position that can be heated by the heater, and measuring the first temperature of the mixed gas at the first position by changing an electrical resistance according to a temperature change, A second temperature sensor disposed at a second position that is not heated by the heater, and measuring the second temperature of the mixed gas at the second position by changing an electrical resistance according to a temperature change, The control device is A gas sensor interface for acquiring the electrical resistance of the first temperature sensor and the electrical resistance of the second temperature sensor, A control device comprising an arithmetic unit that calculates the first temperature of the first temperature sensor when the first temperature sensor is heated by the heater based on the temperature resistance coefficient of the first temperature sensor calculated using the electrical resistance of the first temperature sensor when not heated by the heater, the second temperature calculated using the electrical resistance of the second temperature sensor, the electrical resistance of the first temperature sensor when not heated by the heater, and the electrical resistance of the first temperature sensor when heated by the heater.

10. A control method for controlling a gas sensor that specifies the content rate of at least one type of gas contained in a mixed gas, wherein the gas sensor includes a heat conduction type heater that generates heat in response to supplied power, a first temperature sensor disposed at a first position that can be heated by the heater and that measures the first temperature of the mixed gas at the first position by changing its electrical resistance in response to a temperature change, and a second temperature sensor disposed at a second position that is not heated by the heater and that measures the second temperature of the mixed gas at the second position by changing its electrical resistance in response to a temperature change, and the control method includes, as a process executed by a computer, a step of calculating the temperature resistance coefficient of the first temperature sensor based on the electrical resistance of the first temperature sensor when not heated by the heater, calculating the second temperature based on the electrical resistance of the second temperature sensor, and a step of calculating the first temperature of the first temperature sensor when the first temperature sensor is heated by the heater based on the electrical resistance of the first temperature sensor when not heated by the heater, the electrical resistance of the first temperature sensor when heated by the heater, the temperature resistance coefficient of the first temperature sensor, and the second temperature.

11. A control program for controlling a gas sensor that specifies the content rate of at least one type of gas contained in a mixed gas, wherein the gas sensor includes a heat conduction type heater that generates heat in response to supplied power, a first temperature sensor disposed at a first position that can be heated by the heater and that measures the first temperature of the mixed gas at the first position by changing its electrical resistance in response to a temperature change, A second temperature sensor that is disposed at a second position not heated by the heater and measures a second temperature of the air-fuel mixture at the second position by changing an electrical resistance in response to a temperature change. The control program causes a computer to calculate a temperature-resistance coefficient of the first temperature sensor based on an electrical resistance of the first temperature sensor when not heated by the heater; calculate the second temperature based on an electrical resistance of the second temperature sensor; calculate a first temperature when the first temperature sensor is heated by the heater based on the electrical resistance of the first temperature sensor when not heated by the heater, the electrical resistance of the first temperature sensor when heated by the heater, the temperature-resistance coefficient of the first temperature sensor, and the second temperature. A control program that causes the steps to be executed.

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