Gas sensor and temperature control system and method of gas sensor

Abstract

The invention discloses a gas sensor, and a temperature control system and method for the gas sensor, relates to the technical field of gas sensors, and aims to solve the problem that when the ambient temperature around the gas sensor is reduced, the change of the ambient temperature causes drifting of an output signal of the gas sensor, resulting in errors of a measurement result of the gas sensor. According to the gas sensor, a window is formed in a shell, and a window material used for allowing gas to penetrate through and blocking liquid or solid is arranged at the window. The shell is arranged on the base, and a containing cavity is formed between the shell and the base. The base pin penetrates through the base in the direction from the window to the base. The gas sensor chip is arranged on the first surface of the base; the gas sensor chip is electrically connected with the pins; the heating structure is arranged on the second surface of the base and is electrically connected with the pins; and the heating structure is used for heating the gas sensor chip and the base. The temperature measuring structure is arranged on the first surface of the base, is positioned in the accommodating cavity and is used for measuring the actual temperature around the gas sensor chip.

Description

Technical Field

[0001] The present invention relates to the technical field of gas sensors, and in particular to a gas sensor, a temperature control system and a method for the gas sensor. Background Art

[0002] As the world pays more and more attention to environmental protection and human health, gas concentration sensors, as core components for detecting and measuring gas composition and its concentration, are widely used in environmental monitoring, industrial process control, safety protection, medical health and other fields. For example: real-time monitoring of pollutants in the atmosphere (such as CO2, NO X , SO2, etc.) to prevent air pollution incidents; detect the leakage of flammable and toxic gases, such as hydrogen, methane and ammonia, to prevent industrial accidents; used to detect volatile organic compounds (VOCs) and respiratory gas components in breath as an auxiliary means of disease diagnosis; monitor indoor air quality, detect the concentration of CO or volatile organic compounds (VOC) to ensure the health of the home environment, etc.

[0003] However, when the ambient temperature around the gas sensor decreases, the change in ambient temperature will cause the gas sensor output signal to drift, resulting in errors in the measurement results of the gas sensor. Summary of the invention

[0004] The object of the present invention is to provide a gas sensor, a temperature control system and a method for the gas sensor, which are used to reduce the influence of the lowered ambient temperature on the gas sensor and reduce the measurement error of the gas sensor.

[0005] In order to achieve the above-mentioned purpose, in a first aspect, the present invention provides a gas sensor. The gas sensor comprises: a shell, a base, a pin, a gas sensor chip, a heating structure and a temperature measuring structure. A window is provided on the shell, and a window material is provided at the window. The window material is used to pass gas and block liquid or solid, and the window material closes the window. The shell is provided on the base, and a receiving cavity is provided between the shell and the base. The base has a first surface and a second surface opposite to each other. Part of the pin is located in the receiving cavity, and the pin passes through the base along the direction from the window to the base. The gas sensor chip is provided on the first surface of the base and is located in the receiving cavity, and the gas sensor chip is electrically connected to the pin. The heating structure is provided on the second surface of the base, and the heating structure is electrically connected to the pin, and the heating structure is used to heat the gas sensor chip and the base. The temperature measuring structure is provided on the first surface of the base and is located in the receiving cavity. The temperature measuring structure is electrically connected to the pin, and the temperature measuring structure is used to measure the actual temperature around the gas sensor chip.

[0006] Compared with the prior art, in the gas sensor provided by the present invention, the heating structure is used to heat the gas sensor chip and the base, and the temperature measuring structure is used to measure the actual temperature around the gas sensor chip. Therefore, when the ambient temperature is lower than the operating temperature of the gas sensor chip, the heating structure can heat the gas sensor chip and the base, so that the gas sensor chip is within the operating temperature range, so as to reduce the influence of the ambient temperature below the operating temperature on the gas sensor chip, reduce the drift of the output signal of the gas sensor chip when the ambient temperature changes, thereby reducing the measurement error of the gas sensor and improving the detection accuracy of the gas sensor. Further, since the ambient temperature below the operating temperature will not affect the output signal of the gas sensor chip, the temperature calibration work of the gas sensor only needs to consider the temperature above the operating temperature, reducing the temperature calibration points below the operating temperature and reducing the temperature compensation range of the gas sensor, thereby reducing the temperature calibration work of the gas sensor, saving production costs and improving production efficiency. Further, since the temperature around the gas sensor chip is higher than the ambient temperature, the relative humidity will be lower than the humidity of the environment, and the water vapor is in an unsaturated state. At this time, the condensation of water vapor can be avoided to affect the output signal of the gas sensor chip, ensuring the safety of the gas sensor chip. Based on this, the ambient humidity only needs to be compensated at or above the operating temperature, reducing the humidity calibration points below the operating temperature and the humidity compensation range of the gas sensor, thereby reducing the humidity calibration work of the gas sensor, further saving production costs and further improving production efficiency. In addition, the stress generated by the gas sensor chip during high and low temperature changes can be reduced, avoiding signal abnormalities or damage to the gas sensor chip due to excessive thermal stress, and extending the service life of the gas sensor.

[0007] In one implementation, the temperature measurement structure and the gas sensor chip are located on the same isotherm.

[0008] In one implementation, the heating structure includes: a heating resistance wire and a substrate. The heating resistance wire is arranged on the substrate, and one surface of the substrate is arranged on the second surface of the base.

[0009] In one implementation, the substrate is at least one of a ceramic substrate, a PCB substrate or a silicon substrate; and / or the heating resistance wire is embedded in the substrate; and / or the base includes a central area and a peripheral area surrounding the central area; the heating resistance wire is at least evenly distributed in the peripheral area of ​​the base.

[0010] In one implementation, an insulating glue is filled between the second surface of the base and the substrate, and the insulating glue is used to reduce the thermal resistance from the substrate to the base.

[0011] In one implementation, the shell is made of at least one of stainless steel, aluminum, Kovar alloy or plastic; and / or the base is made of at least one of stainless steel, aluminum, Kovar alloy or plastic.

[0012] In one implementation, the shell is a metal conductive shell, the base is a metal conductive base, and the metal conductive shell and the metal conductive base are connected by conductive paste.

[0013] In a second aspect, the present invention also provides a temperature control system for a gas sensor. The temperature control system of the gas sensor includes the gas sensor, control structure and heating drive circuit described in the above technical solution. The gas sensor includes a temperature measuring structure and a heating structure, and the control structure is electrically connected to the heating structure and the temperature measuring structure, respectively. The control structure is used to obtain the actual temperature measured by the temperature measuring structure, and determine the duty cycle of the PWM wave based on the actual temperature and the preset target temperature; and the control structure controls the heating temperature of the gas sensor by the heating structure through the duty cycle of the PWM wave. One end of the heating drive circuit is electrically connected to the control structure, and the other end of the heating drive circuit is electrically connected to the heating structure, and the PWM wave is used to control the conduction and shutdown of the heating drive circuit.

[0014] Compared with the prior art, the beneficial effects of the temperature control system of the gas sensor provided by the present invention are the same as the beneficial effects of the gas sensor described in the above technical solution, which will not be described in detail here.

[0015] In one implementation, the control structure is an MCU or CPU or DSP or FPGA or CPLD with a built-in PID controller;

[0016] The heating drive circuit is a switch circuit; the switch circuit includes a MOS tube digital switch circuit or a transistor digital switch circuit.

[0017] In a third aspect, the present invention further provides a temperature control method for a gas sensor. The temperature control method for a gas sensor applies the temperature control system for the gas sensor described in the second aspect, and the temperature control method for a gas sensor comprises:

[0018] The actual temperature around the gas sensor chip measured by the temperature measurement structure is obtained by using the control structure;

[0019] The control structure determines the duty cycle of the PWM wave based on the actual temperature and the preset target temperature;

[0020] The PWM wave is used to control the on and off of the heating drive circuit;

[0021] When the heating drive circuit is turned on, the control structure controls the heating temperature of the gas sensor by the heating structure through the duty cycle of the PWM wave.

[0022] Compared with the prior art, the beneficial effects of the temperature control method of the gas sensor provided by the present invention are the same as the beneficial effects of the gas sensor described in the above technical solution, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0024] Figure 1 Schematic diagram of the three-dimensional structure of the gas sensor in an embodiment of the present invention;

[0025] Figure 2 is a front view of a gas sensor according to an embodiment of the present invention;

[0026] Figure 3 A schematic diagram of a gas sensor according to an embodiment of the present invention. Figure 1 ;

[0027] Figure 4 A schematic diagram of a gas sensor according to an embodiment of the present invention. Figure 2 ;

[0028] Figure 5 The structure of the heating structure and the through-hole pad combined in the embodiment of the present invention is shown in FIG. Figure 1 ;

[0029] Figure 6 The structure of the heating structure and the through-hole pad combined in the embodiment of the present invention is shown in FIG. Figure 2 ;

[0030] Figure 7 The structure of the temperature control system of the gas sensor in the embodiment of the present invention is shown in FIG. Figure 1 ;

[0031] Figure 8 The structure of the temperature control system of the gas sensor in the embodiment of the present invention is shown in FIG. Figure 2 ;

[0032] Fig. 9 Schematic diagram of the PID temperature control algorithm in an embodiment of the present invention.

[0033] Reference numerals:

[0034] 1-gas sensor, 10-housing, 11-base, 12-pin, 13-gas sensor chip; 14-heating structure, 140-heating resistor wire, 141-substrate; 15-temperature measurement structure, 16-window material, 2-through hole pad, 3-control structure, 4-heating drive circuit. DETAILED DESCRIPTION

[0035] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0036] It should be noted that when an element is referred to as being "fixed on" or "disposed on" another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or indirectly connected to the other element. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. The meaning of "several" is one or more, unless otherwise clearly and specifically defined.

[0037] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by the terms "up", "down", "front", "back", "left", "right", etc. are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0038] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] Combined with the description in the background technology section, most types of gas sensors have temperature drift, that is, the change of ambient temperature causes the drift of the gas sensor output signal, resulting in errors in the measurement results. The occurrence of temperature drift is related to the temperature characteristics of the sensitive materials of the gas sensor. For example, the sensitive elements of thermal conductivity gas sensors are mostly temperature-sensitive elements such as thermistors and thermopiles. The change of ambient temperature directly causes the deviation of the gas sensor output signal; the conductivity of the semiconductor sensitive material of the semiconductor gas sensor is highly sensitive to temperature. The carrier concentration inside the material changes with temperature, and the conductivity also changes accordingly, resulting in drift in the detection results. The occurrence of temperature drift is related to the physical or chemical process inside the gas sensor. The temperature will affect the rate and degree of the internal chemical reaction of the electrochemical gas sensor when it is working, and will also affect the adsorption and desorption behavior of gas molecules when interacting with the surface of the sensitive material, which will affect the detection results and performance of the gas sensor. Therefore, temperature drift compensation and correction of gas sensors are essential. In the case of high-precision gas detection or large fluctuations in the working environment temperature, the suppression and correction of temperature drift are particularly important. In addition, environmental humidity also affects the working state of the gas sensor. For example, humidity will change the thermal conductivity of the gas to be measured, causing the output signal of the thermal conductivity gas sensor to drift; excessive relative humidity in the environment will cause water vapor condensation, which may cause abnormal gas sensor output signals or even damage the gas sensor chip. In addition, in extreme environments, the internal structure of the gas sensor will deform due to thermal stress caused by large-scale temperature changes.

[0040] In order to solve some of the above technical problems, in the first aspect, the present invention provides a gas sensor. The types of the above gas sensor chips are various. For example, the above gas sensor is a MEMS (Micro-Electro-Mechanical System) gas sensor. The MEMS gas sensor does not limit the type of sensor, for example, it can be a thermal conductivity gas sensor, an electrochemical gas sensor, an infrared gas sensor, a metal oxide semiconductor gas sensor, etc. It should be noted that the types of the above gas sensors are not limited to the above description.

[0041] The introduction of MEMS technology has led to the miniaturization of gas sensors, which has greatly reduced the size of the device, reduced power consumption, and reduced manufacturing costs. At the same time, MEMS technology has made the mass production and integration of gas sensors more convenient. Furthermore, MEMS gas sensors have been widely used in portable devices and Internet of Things (IoT) devices.

[0042] See also Figures 1 to 6The gas sensor 1 comprises: a shell 10, a base 11, a pin 12, a gas sensor chip 13, a heating structure 14 and a temperature measuring structure 15. A window is provided on the shell 10, and a window material 16 is provided at the window. The window material 16 is used to pass gas and block liquid or solid, and the window material 16 closes the window. The shell 10 is provided on the base 11, and a receiving cavity is provided between the shell 10 and the base 11. The base 11 has a first surface and a second surface opposite to each other. A part of the pin 12 is located in the receiving cavity, and the pin 12 passes through the base 11 along the direction from the window to the base 11. The gas sensor chip 13 is provided on the first surface of the base 11 and is located in the receiving cavity. The gas sensor chip 13 is electrically connected to the pin 12. The heating structure 14 is provided on the second surface of the base 11, and the heating structure 14 is electrically connected to the pin 12. The heating structure 14 is used to heat the gas sensor chip 13 and the base 11. The temperature measuring structure 15 is provided on the first surface of the base 11 and is located in the receiving cavity. The temperature measuring structure 15 is electrically connected to the pin 12 , and is used to measure the actual temperature around the gas sensor chip 13 .

[0043] See also Figures 1 to 6In the gas sensor provided by the embodiment of the present invention, the heating structure 14 is used to heat the gas sensor chip 13 and the base 11, and the temperature measuring structure 15 is used to measure the actual temperature around the gas sensor chip 13. Therefore, when the ambient temperature is lower than the working temperature of the gas sensor chip 13, the heating structure 14 can heat the gas sensor chip 13 and the base 11, so that the gas sensor chip 13 is within the working temperature range, so as to reduce the influence of the ambient temperature below the working temperature on the gas sensor chip 13, and reduce the drift of the output signal of the gas sensor chip 13 when the ambient temperature changes, thereby reducing the measurement error of the gas sensor and improving the detection accuracy of the gas sensor. Furthermore, since the ambient temperature below the working temperature will not affect the output signal of the gas sensor chip 13, the temperature calibration work of the gas sensor only needs to consider the temperature above the working temperature, reducing the temperature calibration points below the working temperature and reducing the temperature compensation range of the gas sensor, thereby reducing the temperature calibration work of the gas sensor, saving production costs and improving production efficiency. Furthermore, since the temperature around the gas sensor chip 13 is higher than the ambient temperature, the relative humidity will be lower than the humidity of the environment, and the water vapor is in an unsaturated state. At this time, the condensation of water vapor can be prevented from affecting the output signal of the gas sensor chip 13, ensuring the safety of the gas sensor chip 13. Based on this, the ambient humidity only needs to be compensated at the operating temperature and above, reducing the humidity calibration points below the operating temperature and reducing the humidity compensation range of the gas sensor, thereby reducing the humidity calibration work of the gas sensor, further saving production costs, and further improving production efficiency. In addition, the stress generated by the gas sensor chip 13 during high and low temperature changes can be reduced, avoiding the signal abnormality or damage of the gas sensor chip 13 due to excessive thermal stress, and extending the service life of the gas sensor.

[0044] As a possible implementation manner, the shell is made of at least one of stainless steel, aluminum, Kovar alloy or plastic; and / or the base is made of at least one of stainless steel, aluminum, Kovar alloy or plastic.

[0045] As a possible implementation, the housing is a metal conductive housing, the base is a metal conductive base, and the metal conductive housing and the metal conductive base are connected by a conductive paste. Exemplarily, the housing is a stainless steel housing, the base is a stainless steel base, and the conductive paste is silver paste.

[0046] When the above technical solution is adopted, in actual use, the pins electrically connected to the base are grounded, and devices such as the gas sensor chip are electromagnetically isolated from the external environment, which can avoid electromagnetic interference during analog signal transmission.

[0047] In an embodiment of the present invention, the base is a TO tube socket. Further, the metal conductive shell and the metal conductive base can be bonded or welded together by conductive paste, and the base and the shell are connected to the signal ground of PCB (Printed Circuit Board) to form electromagnetic isolation.

[0048] In order to facilitate the diffusion of gas into the accommodating cavity and prevent liquid or solid particles from entering the accommodating cavity to damage the gas sensor chip, wires and other devices, the above-mentioned window material can be a waterproof breathable membrane or a filter. Exemplarily, when the window material is a waterproof breathable membrane, the material of the waterproof breathable membrane can be polytetrafluoroethylene or other polymer materials. When the window material is a filter, the material of the filter can be metal, alloy or plastic. Furthermore, the above-mentioned filter is a porous capillary mesh structure, preferably a polymer, metal or alloy material.

[0049] As a possible implementation, the gas sensor chip can be bonded or welded to the first surface of the base. Exemplarily, the gas sensor chip is bonded to the first surface of the base by silver paste, glass paste or other materials with adhesive properties. Furthermore, the gas sensor chip is electrically connected to the pin through a wire, and the signal of the gas sensor is led to the pin by a wire (such as a gold wire), and then led out by the pin.

[0050] As a possible implementation, see Figure 2 , Figure 5 and Figure 6 The heating structure 14 includes a heating resistor 140 and a substrate 141. The heating resistor 140 is disposed on the substrate 141, and one side of the substrate 141 is disposed on the second side of the base 11.

[0051] Exemplarily, the substrate 141 is cylindrical, and one circular side of the cylindrical substrate is in close contact with the second side of the base 11. The size of the circular side and the size of the second side of the base 11 can be set according to actual needs, for example, the area of ​​the circular side is smaller than the area of ​​the second side of the base 11. Furthermore, the connection method of the circular side and the second side of the base 11 can be bonding or welding.

[0052] In order to facilitate the conduction of heat generated by the heating resistor wire to the gas sensor chip and the base and other structures, the substrate is made of a material with good thermal conductivity. In an optional manner, the substrate is at least one of a ceramic substrate, a PCB substrate or a silicon substrate. Exemplarily, when the substrate is a ceramic substrate, it is an alumina ceramic substrate.

[0053] Combined with the above description, in the embodiment of the present invention, the substrate is a cylindrical ceramic substrate. Using a ceramic substrate with a large thermal conductivity as a surface heat source can reduce the temperature gradient between the temperature measurement structure and the gas sensor chip, ensuring that the temperature measurement structure can accurately measure the gas sensor chip and the ambient temperature around it, thereby obtaining accurate actual temperature and improving the accuracy of temperature regulation.

[0054] The relative position relationship between the heating resistor wire and the substrate can be set according to actual conditions. For example, the heating resistor wire can be set on the surface of the substrate facing the second surface of the base, or the heating resistor wire is embedded in the surface of the substrate facing the second surface of the base, or the heating resistor wire is embedded in the substrate. When the heating resistor wire is embedded in the surface or inside of the substrate, the substrate can be evenly heated, thereby achieving the maximum efficiency of heating the base and the gas sensor chip.

[0055] The distribution of the heating resistor wires on the substrate is not specifically limited. Figure 5 As shown, a plurality of heating resistor wires 140 are distributed on a substrate 141 in a concentric circle manner, and the center of the concentric circle is the center of the circular substrate. A plurality of through-hole pads 2 are distributed at equal intervals inside the heating resistor wire 140 closest to the center of the circular substrate, and the top view of the through-hole pads 2 is a semicircle. Alternatively, as Figure 6 As shown, a plurality of heating resistor wires 140 are distributed on the substrate 141 in a roughly C-shaped manner, and the plurality of heating resistor wires 140 can be symmetrically distributed with the diameter of the circular substrate as the symmetry axis. Further, a plurality of equally spaced circular through-hole pads 2 are located between the heating resistor wires 140. It should be noted that no matter how the through-hole pads 2 and the heating resistor wires 140 are distributed, the pins at both ends of the heating resistor wire 140 are led out through the through-hole pads 2. For example, there are 8 through-hole pads 2 distributed on the substrate 141, two of which are used to lead out the pins of the heating resistor wire 140 and are connected to the pins 12, at which time an external power supply (such as an external DC power supply) can heat the heating resistor wire 140 through the pins 12. The remaining through-hole pads 2 are used to fix the substrate 141 to the second surface of the base 11.

[0056] The relative position relationship between the above-mentioned heating resistance wire 140 and the base 11 can be set according to actual conditions. For example, the heating resistance wire 140 is evenly distributed in all areas of the base 11 to heat the entire base 11; or, the base 11 includes a central area and a peripheral area surrounding the central area, and the heating resistance wire 140 is at least evenly distributed in the peripheral area of ​​the base 11.

[0057] As a possible implementation manner, an insulating glue is filled between the second surface of the base and the substrate, and the insulating glue is used to reduce the thermal resistance from the substrate to the base.

[0058] Exemplarily, the gap between the second surface of the base and the substrate is filled with insulating glue with high thermal conductivity to reduce the thermal resistance from the substrate to the base, thereby increasing the heating rate of the sensor chip, reducing the impact of ambient temperature below the operating temperature on the gas sensor chip, and improving the detection accuracy of the gas sensor.

[0059] As a possible implementation method, the temperature measurement structure and the gas sensor chip are located on the same isotherm. In this case, the temperature measurement structure can accurately obtain the temperature of the gas sensor chip by measuring the temperature around the gas sensor chip.

[0060] In an alternative approach, see Figure 3 The temperature measurement structure 15 and the gas sensor chip 13 are located in the central area of ​​the base 11 .

[0061] In one example, the temperature is highest at the center of the base, and the temperature gradually decreases in the direction away from the center of the base. Moreover, the temperature line with the center of the base as the center is the isotherm, so the temperature measurement structure and the gas sensor chip are located on the same circular isotherm.

[0062] In an alternative approach, see Figure 3 The temperature measuring structure 15 is electrically connected to the pin 12 through a wire (such as a gold wire, an aluminum wire or a lead made of other conductive materials). The temperature measuring structure 15 can be a separate temperature measuring module (such as a thermistor, a temperature sensitive diode, a temperature sensor chip, etc.), or a temperature measuring element integrated in the gas sensor.

[0063] In a second aspect, an embodiment of the present invention further provides a temperature control system for a gas sensor. Figures 1 to 8 The temperature control system of the gas sensor includes the gas sensor 1, the control structure 3 and the heating drive circuit 4 described in the above technical solution. The gas sensor 1 includes a temperature measuring structure 15 and a heating structure 14, and the control structure 3 is electrically connected to the heating structure 14 and the temperature measuring structure 15 respectively. The control structure 3 is used to obtain the actual temperature measured by the temperature measuring structure 15, and determine the duty cycle of the PWM wave based on the actual temperature and the preset target temperature; and the control structure 3 controls the heating temperature of the gas sensor by the heating structure 14 through the duty cycle of the PWM wave. One end of the heating drive circuit 4 is electrically connected to the control structure 3, and the other end of the heating drive circuit 4 is electrically connected to the heating structure 14, and the PWM wave is used to control the conduction and shutdown of the heating drive circuit 4.

[0064] The beneficial effects of the temperature control system of the gas sensor provided by the embodiment of the present invention are the same as the beneficial effects of the gas sensor described in the above technical solution, and will not be described in detail here.

[0065] As a possible implementation method, the above-mentioned control structure is an MCU (Microcontroller Unit) or a CPU (Central Processing Unit) or a DSP (Digital Signal Processor) or an FPGA (Field Programmable Gate Array) or a CPLD (Complex Programmable logic device) with a built-in PID controller; it should be noted that the specific structure of the above-mentioned MCU or CPU or DSP or FPGA or CPLD can be referred to the prior art and is not specifically limited here.

[0066] Since the control structure has a built-in PID controller, a PID temperature control algorithm can be written into the control structure to control the heating structure to heat the gas sensor chip.

[0067] As a possible implementation, the heating drive circuit is a switch circuit. Of course, the heating drive circuit can also be other circuit forms that can adjust the heating power. In an optional manner, the switch circuit includes a MOS tube digital switch circuit or a transistor digital switch circuit.

[0068] For example, see Figure 7 and Figure 8 The MOS tube digital switch circuit includes a diode D, an NMOS tube and a resistor R. The anode of the diode D is electrically connected to the control structure 3, the cathode of the diode D is electrically connected to one end of the NMOS tube and one end of the resistor R respectively, the other end of the NMOS tube and the other end of the resistor R are electrically connected to the ground, and the remaining end of the NMOS tube is electrically connected to the gas sensor.

[0069] As can be seen from the foregoing description, the above-mentioned PWM wave and the heating drive circuit together constitute a heating power regulation circuit.

[0070] In a third aspect, an embodiment of the present invention further provides a method for controlling the temperature of a gas sensor. The temperature control method of the gas sensor described above applies the temperature control system of the gas sensor described in the second aspect, see Figures 1 to 9 , the temperature control method of the gas sensor may include:

[0071] First, the actual temperature around the gas sensor chip 13 measured by the temperature measurement structure 15 is obtained by using the control structure 3;

[0072] Exemplarily, the gas sensor 1 transmits the actual temperature around the gas sensor chip 13 measured by the temperature measurement structure 15 to the control structure 3 through the pin 12 .

[0073] Next, the control structure 3 determines the duty cycle of the PWM wave based on the actual temperature and the preset target temperature;

[0074] Exemplarily, the control structure 3 determines the temperature difference based on the actual temperature and the preset target temperature. Then, the temperature difference is input into the PID temperature control algorithm of the control structure 3 to obtain the temperature control increment. Then, the control structure 3 determines the duty cycle of the PWM wave based on the temperature control increment. It should be noted that the above PWM wave is output by the IO pin 12 of the control structure 3 (e.g., MCU).

[0075] Next, the PWM wave is used to control the on and off of the heating drive circuit 4;

[0076] Exemplarily, when it is necessary to control the heating structure 14 to heat the gas sensor, the PWM wave controls the heating drive circuit 4 to turn on (for example, controls the NMOS tube in the heating drive circuit 4 to turn on).

[0077] Next, when the heating drive circuit 4 is turned on, the control structure 3 controls the heating temperature of the gas sensor by the heating structure 14 through the duty cycle of the PWM wave.

[0078] Exemplarily, the control structure 3 adjusts the heating power of the heating resistor 140 to the substrate 141 and other structures through the duty cycle of the PWM wave, thereby controlling the heating temperature of the gas sensor by the heating structure 14 .

[0079] As can be seen from the above, the actual temperature of the base 11, the gas sensor chip 13 and the surrounding of the gas sensor chip 13 is measured by the temperature measuring structure 15 and transmitted to the control structure 3 through the pin 12. The PID temperature control algorithm is written into the control structure 3, and the actual temperature measured by the above temperature measuring structure 15 is used as a feedback signal. The control structure 3 outputs PWM waves with different duty cycles according to the temperature difference between the actual temperature and the preset target temperature. By outputting PWM waves with different duty cycles, the heating power of the heating resistor 140 to the substrate 141 is controlled, and the heating power to the base 11 and the gas sensor chip 13 is adjusted until the temperature measured by the temperature measuring structure 15 stabilizes at the desired temperature value, thereby achieving temperature control of the gas sensor.

[0080] The beneficial effects of the temperature control method of the gas sensor provided by the embodiment of the present invention are the same as the beneficial effects of the gas sensor described in the above technical solution, and will not be described in detail here.

[0081] Although the present invention is described herein in conjunction with various embodiments, in the process of implementing the claimed invention, those skilled in the art may understand and implement other variations of the disclosed embodiments by viewing the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other components or steps, and "one" or "an" does not exclude multiple situations. A single processor or other unit may implement several functions listed in the claims. Certain measures are recorded in mutually different dependent claims, but this does not mean that these measures cannot be combined to produce good results. Although the present invention has been described in conjunction with specific features and embodiments thereof, it is obvious that various modifications and combinations may be made thereto without departing from the spirit and scope of the present invention. Accordingly, this specification and the drawings are merely exemplary illustrations of the present invention as defined by the appended claims, and are deemed to have covered any and all modifications, variations, combinations or equivalents within the scope of the present invention. Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A gas sensor, characterized in that: include: A shell, wherein a window is formed on the shell, and a window material is disposed at the window; the window material is used to allow gas to pass through and block liquid or solid; the window material seals the window; A base, the shell is arranged on the base; a receiving cavity is provided between the shell and the base; the base has a first surface and a second surface opposite to each other; A pin, a portion of which is located in the accommodating cavity; Along the direction from the window to the base, the pin passes through the base; A gas sensor chip is disposed on the first surface of the base and is located in the accommodating cavity; the gas sensor chip is electrically connected to the pin; A heating structure is disposed on the second surface of the base, the heating structure is electrically connected to the pin; the heating structure is used to heat the gas sensor chip and the base; A temperature measuring structure is arranged on the first surface of the base and is located in the accommodating cavity; the temperature measuring structure is electrically connected to the pin; and the temperature measuring structure is used to measure the actual temperature around the gas sensor chip.

2. The gas sensor according to claim 1, characterized in that The temperature measurement structure and the gas sensor chip are located on the same isotherm.

3. The gas sensor according to claim 1, characterized in that: The heating structure comprises: Heating resistance wire; The heating resistor wire is arranged on the substrate, and one surface of the substrate is arranged on the second surface of the base.

4. The gas sensor according to claim 3, characterized in that: The substrate is at least one of a ceramic substrate, a PCB substrate or a silicon substrate; And / or, the heating resistance wire is embedded in the substrate; And / or, the base includes a central area and a peripheral area surrounding the central area; the heating resistance wires are at least evenly distributed in the peripheral area of ​​the base.

5. The gas sensor according to claim 3, characterized in that: Insulating glue is filled between the second surface of the base and the substrate, and the insulating glue is used to reduce the thermal resistance from the substrate to the base.

6. The gas sensor according to claim 1, characterized in that The shell is made of at least one of stainless steel, aluminum, Kovar alloy or plastic; And / or, the base is made of at least one of stainless steel, aluminum, Kovar alloy or plastic.

7. The gas sensor according to claim 1, characterized in that: The shell is a metal conductive shell, the base is a metal conductive base, and the metal conductive shell and the metal conductive base are connected by conductive paste.

8. A temperature control system for a gas sensor, characterized in that: include: A gas sensor, wherein the gas sensor is the gas sensor according to any one of claims 1 to 7; the gas sensor comprises a temperature measuring structure and a heating structure; a control structure, electrically connected to the heating structure and the temperature measuring structure, respectively, the control structure being used to obtain the actual temperature measured by the temperature measuring structure, and determine the duty cycle of the PWM wave based on the actual temperature and a preset target temperature; and the control structure controls the heating temperature of the gas sensor by the heating structure through the duty cycle of the PWM wave; A heating drive circuit, one end of the heating drive circuit is electrically connected to the control structure, and the other end of the heating drive circuit is electrically connected to the heating structure; the PWM wave is used to control the on and off of the heating drive circuit.

9. The temperature control system of the gas sensor according to claim 8, characterized in that: The control structure is an MCU or CPU or DSP or FPGA or CPLD with a built-in PID controller; The heating drive circuit is a switch circuit; the switch circuit includes a MOS tube digital switch circuit or a transistor digital switch circuit.

10. A temperature control method for a gas sensor, characterized in that: The temperature control system of the gas sensor according to claim 8 or 9 is applied, and the temperature control method of the gas sensor comprises: Using the control structure to obtain the actual temperature around the gas sensor chip measured by the temperature measurement structure; The control structure determines the duty cycle of the PWM wave based on the actual temperature and the preset target temperature; The PWM wave is used to control the on and off of the heating drive circuit; When the heating drive circuit is turned on, the control structure controls the heating temperature of the gas sensor by the heating structure through the duty cycle of the PWM wave.

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