Thermal conductivity type gas detection device

Abstract

The invention provides a thermal conductivity type gas detection device. The output voltage of the feedback tracking module at the initial moment is equal to the output voltage of the voltage stabilizing source, and the resistance values of the two heating resistors are equal, so that the temperatures of the two cavities are equal at the initial moment. If the gas with the poor thermal conductivity is mixed, the temperature of the detection cavity rises, the resistance value of the second NTC thermistor is reduced, the output voltage of the feedback tracking module is reduced, the heating power of the second heating resistor is reduced, the temperature of the detection cavity is reduced, and the temperature of the two cavities is equal finally through circulation. Therefore, the concentration of the gas mixed into the detection cavity can be detected by utilizing the variable quantity of the output voltage of the feedback tracking module. The temperature of the final detection cavity is the same as that of the reference cavity, so that the working temperatures of the two NTC thermistors are the same, and the calorific values tend to be the same, thereby reducing the difference value between the deviations of the resistance values of the two NTC thermistors, and improving the detection precision of the thermal conductivity type gas detection device.

Description

Technical Field

[0001] This invention relates to the field of measurement technology, and in particular to a thermal conductivity gas detection device. Background Technology

[0002] Thermal conductivity gas detection devices are used to detect whether gases with different thermal conductivity are mixed in the environment and the concentration of the mixed gases. They have many advantages that gas sensors do not have, such as a large detection range, high reliability, simple device, low price, and convenient maintenance.

[0003] Thermal conductivity gas detection devices consist of a detection chamber and a reference chamber, typically using NTC thermistors for temperature measurement. When different concentrations of gas are introduced into the detection chamber, the temperature of the detection chamber changes compared to the reference chamber. This causes a change in the resistance of the NTC thermistor in the detection chamber compared to the one in the reference chamber. The concentration of the introduced gas can then be detected based on the resistance difference between the two thermistors. However, the presence of different gas concentrations in the detection chamber leads to different temperatures in the two chambers during detection. Consequently, the operating temperatures of the two NTC thermistors differ, resulting in a deviation between their resistance values ​​and the resistance values ​​corresponding to the actual measured temperature. This can easily lead to lower detection accuracy in thermal conductivity gas detection devices, making them unsuitable for applications requiring high precision.

[0004] Therefore, improving the detection accuracy of thermally conductive gas detection devices is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] In view of this, the present invention provides a thermal conductivity gas detection device to improve the detection accuracy of thermal conductivity gas detection devices.

[0006] To achieve the above objectives, the following technical solution is provided:

[0007] A thermal conductivity gas detection device includes: a voltage regulator, a first module, a feedback tracking module, a first heating resistor, and a second heating resistor; wherein:

[0008] The first module includes a first NTC thermistor and a second NTC thermistor;

[0009] The first heating resistor is disposed in the reference cavity, one end of the first heating resistor is connected to the output terminal of the voltage regulator, and the other end of the first heating resistor is grounded. The first NTC thermistor is disposed in the reference cavity.

[0010] The second heating resistor is disposed in the detection cavity. One end of the second heating resistor is connected to the output terminal of the feedback tracking module, and the other end of the second heating resistor is grounded. The second NTC thermistor is disposed in the detection cavity.

[0011] The resistance of the first heating resistor is equal to the resistance of the second heating resistor; the output terminal of the first module is connected to the input terminal of the feedback tracking module;

[0012] The feedback tracking module can output a variable voltage.

[0013] In this technical solution, the voltage across the first heating resistor is equal to the output voltage of the regulated source. The feedback tracking module can output a variable voltage. When the voltage value output by the feedback tracking module is equal to the output voltage of the regulated source, the heating power of the first and second heating resistors is the same, and the temperatures collected by the first and second NTC thermistors are the same. Under a fixed heat dissipation condition in standard atmosphere, excluding other influencing factors, when the temperature of the detection cavity and the reference cavity is determined solely by the heating power of the first and second heating resistors, the temperature of the detection cavity is the same as that of the reference cavity. Therefore, the resistance values ​​of the first and second NTC thermistors are the same. When gases with different thermal conductivity are mixed in, the voltage across the two NTC thermistors is the same. Therefore, a temperature difference exists between the detection chamber and the reference chamber, resulting in different resistance values ​​for the first and second NTC thermistors. Since the feedback tracking module can output a variable voltage, the voltage across the second heating resistor changes, causing the heating power of the second heating resistor to be superimposed with the heat generated by the mixed gas. This results in the two chambers reaching the same final temperature, making the operating temperatures of the two NTC thermistors identical. This reduces the difference in resistance values ​​between the two thermistors, and the heat generation becomes nearly identical, further reducing the deviation in the output voltage of the feedback tracking module. Therefore, the detection accuracy of the thermal conductivity gas detection device is improved.

[0014] This application also provides a thermally conductive gas detection device, comprising: a voltage regulator, a first module, a feedback tracking module, a first heating resistor, and a second heating resistor; wherein:

[0015] The first module includes a first NTC thermistor and a second NTC thermistor;

[0016] The first heating resistor is disposed in the reference cavity, one end of the first heating resistor is connected to the output terminal of the voltage regulator, and the other end of the first heating resistor is grounded. The first NTC thermistor is disposed in the reference cavity.

[0017] The second heating resistor is disposed in the detection cavity. One end of the second heating resistor is connected to the output terminal of the feedback tracking module, and the other end of the second heating resistor is grounded. The second NTC thermistor is disposed in the detection cavity.

[0018] The resistance value of the first heating resistor is equal to the resistance value of the second heating resistor; the output terminal of the first module is connected to the feedback tracking module;

[0019] The output of the first module can be used to obtain the ratio of the voltage across the second NTC thermistor to the voltage across the first NTC thermistor. The initial ratio of the voltage across the second NTC thermistor to the voltage across the first NTC thermistor is defined as X. The initial voltage value output by the feedback tracking module is equal to the output voltage value of the regulated source. The feedback tracking module can adjust its output voltage accordingly when the ratio of the voltage across the second NTC thermistor to the voltage across the first NTC thermistor changes compared to the initial ratio X.

[0020] Assuming the thermal conductivity of the gas in the detection chamber and the reference chamber is the same at the initial moment, the voltage across the first heating resistor is equal to the output voltage of the regulated source, and the voltage across the second heating resistor is equal to the output voltage of the feedback tracking module. Since the output voltage of the feedback tracking module is equal to the output voltage of the regulated source at the initial moment, and the resistance of the first heating resistor is equal to that of the second heating resistor, the heating power of the first heating resistor and the second heating resistor is equal. Therefore, under a fixed heat dissipation condition in standard atmosphere, excluding other influencing factors, and only determined by the heating power of the first heating resistor and the second heating resistor, the temperature of the detection chamber is the same as that of the reference chamber at the initial moment. The ratio of the voltage across the first thermistor and the voltage across the second thermistor at the initial moment is set to X. If a gas with poor thermal conductivity enters the detection chamber, the temperature of the detection chamber will rise, and the resistance of the second NTC thermistor will decrease. That is, the ratio of the voltage across the second NTC thermistor to the voltage across the first NTC thermistor will decrease. This causes the feedback tracking module to reduce its own output voltage, reducing the heating power of the second heating resistor, and further lowering the temperature of the detection chamber. This cycle repeats until the ratio of the voltage across the first thermistor to the voltage across the second thermistor equals the initial ratio X. If a gas with high thermal conductivity enters the detection chamber, the adjustment process is the reverse of the above process, which will not be elaborated here. As can be seen from the above, the change in the output voltage of the feedback tracking module will vary depending on the concentration of the gas entering the detection chamber. Therefore, the concentration of the gas entering the detection chamber can be detected by utilizing the change in the output voltage of the feedback tracking module. Since the temperature of the final detection chamber is the same as that of the reference chamber during the above adjustment process, the heat generated by the two NTC thermistors is the same, thereby reducing the difference between the resistance values ​​of the two NTC thermistors, and thus reducing the deviation of the output voltage of the feedback tracking module, thereby improving the detection accuracy of the thermal conductivity gas detection device. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the structure of a first embodiment of the thermal conductivity gas detection device provided in this application.

[0023] Figure 2 This is a schematic diagram of the second embodiment of the thermal conductivity gas detection device provided in this application.

[0024] Figure 3 This is a schematic diagram of the third embodiment of the thermal conductivity gas detection device provided in this application.

[0025] Figure 4 This is a schematic diagram of the fourth embodiment of the thermal conductivity gas detection device provided in this application.

[0026] Figure 5 This is a schematic diagram of one embodiment of the resistor branch provided in this application.

[0027] Figure 6 This is a schematic diagram of one arrangement between the first NTC thermistor Rr1 and the first heating resistor Rj1.

[0028] Figure 7 This is a schematic diagram of another arrangement between the first NTC thermistor Rr1 and the first heating resistor Rj1. Detailed Implementation

[0029] The technical solution of this application will be further described below with reference to the accompanying drawings and specific embodiments.

[0030] In this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0031] To improve the detection accuracy of thermal conductivity gas detection devices, this application provides a thermal conductivity gas detection device, the specific structure of which is as follows: Figures 1-4 As shown, it specifically includes: a voltage regulator 30, a first module 10, a feedback tracking module 20, a first heating resistor Rj1, and a second heating resistor Rj2;

[0032] The first module 10 includes a first NTC thermistor Rr1 and a second thermistor Rr2.

[0033] refer to Figure 1 , Figure 2 As one specific implementation method, the connection relationships between the various devices are as follows:

[0034] The first heating resistor Rj1 is set in the reference cavity 01. One end of the first heating resistor Rj1 is connected to the output terminal of the voltage regulator 30, and the other end of the first heating resistor Rj1 is grounded to GND.

[0035] The first NTC thermistor Rr1 is disposed in the reference cavity 01. One end of the first NTC thermistor Rr1 is connected to the output terminal of the voltage regulator 30, and the other end of the first NTC thermistor Rr1 is connected to the second NTC thermistor Rr2.

[0036] The second heating resistor Rj2 is set in the detection cavity 02. One end of the second heating resistor Rj2 is connected to the output terminal of the feedback tracking module 20, and the other end of the second heating resistor Rj2 is grounded to GND.

[0037] The second NTC thermistor Rr2 is placed in the detection cavity O2. One end of the second NTC thermistor Rr2 is connected to the first NTC thermistor Rr1, and the other end of the second NTC thermistor Rr2 is grounded to GND.

[0038] The feedback tracking module 20 can output a variable voltage.

[0039] The resistance value of the first heating resistor Rj1 is equal to the resistance value of the second heating resistor Rj2. It is worth noting that in actual production, it is difficult to manufacture resistors that perfectly match their nominal resistance values; that is, the resistance values ​​have a certain degree of variation. Therefore, when this article refers to the first heating resistor Rj1 and the second heating resistor Rj2 having equal resistance values, it means that their nominal resistance values ​​are the same, allowing for deviations due to manufacturing processes, etc.

[0040] With this setup, the first thermistor Rr1 and the second thermistor Rr2 are located in two chambers, one as a reference chamber and the other as a detection chamber. The detection chamber has a through hole to allow gas to circulate with the outside, while the reference chamber is a sealed chamber. The first thermistor Rr1 detects the temperature inside the reference chamber, and the second thermistor detects the temperature inside the reference chamber. By using the controlled variable method, the temperature change of the reference chamber is represented by the resistance value of the first thermistor Rr1, which is equivalent to a dynamic zero point for the second thermistor Rr2. Therefore, the detection results can be more accurate.

[0041] In a specific example, both the first heating resistor Rj1 and the second heating resistor Rj2 are precision resistors. Since it is easy to control the error of precision resistors to within 1%, it is very convenient and accurate to control the heat generation of both and to optimize their temperature points.

[0042] The first module 10 can be used to obtain the ratio of the voltage across the second NTC thermistor Rr2 to the voltage across the first NTC thermistor Rr1. The first output terminal of the first module 10 is connected to the first input terminal of the feedback tracking module 20, and the second output terminal of the first module 10 is connected to the second input terminal of the feedback tracking module 20.

[0043] The feedback tracking module 20 can be used to change its output voltage when the ratio of the voltage Rr1 across the second NTC thermistor to the voltage across the first NTC thermistor Rr1 changes; the initial time is set when the thermal conductivity of the gas in the detection chamber and the reference chamber is the same, and the voltage value output by the feedback tracking module 20 at the initial time is equal to the output voltage value of the voltage regulator 30.

[0044] Specifically, when the ratio of the voltage across the second NTC thermistor Rr2 to the voltage across the first NTC thermistor Rr1 decreases, the feedback tracking module 20 lowers its own output voltage; when the ratio of the voltage across the second NTC thermistor Rr2 to the voltage across the first NTC thermistor Rr1 increases, the feedback tracking module 20 raises its own output voltage.

[0045] It is worth noting that, initially, the voltage output of the feedback tracking module 20 is equal to the output voltage of the voltage regulator 30. That is, when the thermal conductivity of the gas in the detection chamber is equal to that of the gas in the reference chamber, the output voltage of the feedback tracking module 20 is equal to the output voltage of the voltage regulator 30.

[0046] Specifically, the initial moment is set when the thermal conductivity of the gas in the detection chamber and the reference chamber is the same. The voltage across the first heating resistor Rj1 is equal to the output voltage of the regulated source 30, and the voltage across the second heating resistor Rj2 is equal to the output voltage of the feedback tracking module 20. Since the output voltage of the feedback tracking module 20 is equal to the output voltage of the regulated source 30 at the initial moment, and the resistance of the first heating resistor Rj1 is equal to that of the second heating resistor Rj2, the heating power of the first heating resistor Rj1 and the second heating resistor Rj2 is equal. Therefore, under a fixed heat dissipation condition in a standard atmosphere, excluding other influencing factors, and only the heating power of the first heating resistor Rj1 and the second heating resistor Rj2 determines the temperature of the detection chamber and the reference chamber, the temperature of the detection chamber is the same as that of the reference chamber at the initial moment. The ratio of the voltage across the first thermistor and the voltage across the second thermistor at the initial moment is set to X. If a gas with poor thermal conductivity enters the detection chamber, the temperature of the detection chamber will rise, and the resistance of the second NTC thermistor will decrease. That is, the ratio of the voltage across the second NTC thermistor to the voltage across the first NTC thermistor will decrease. This causes the feedback tracking module 20 to reduce its own output voltage, reducing the heating power of the second heating resistor Rj2, and further lowering the temperature of the detection chamber. This cycle repeats until the ratio of the voltage across the first thermistor to the voltage across the second thermistor equals the initial ratio X. If a gas with high thermal conductivity enters the detection chamber, the adjustment process is the reverse of the above process, which will not be elaborated here. As can be seen from the above, the change in the output voltage of the feedback tracking module 20 will vary depending on the concentration of the gas entering the detection chamber. Therefore, the concentration of the gas entering the detection chamber can be detected by utilizing the change in the output voltage of the feedback tracking module 20. Since the temperature of the final detection chamber is the same as that of the reference chamber during the above adjustment process, the heat generated by the two NTC thermistors is the same and the operating temperature is the same. This reduces the difference between the resistance values ​​of the two NTC thermistors, thereby reducing the deviation of the output voltage of the feedback tracking module 20 and improving the detection accuracy of the thermal conductivity gas detection device.

[0047] Another embodiment of this application provides another implementation of a thermal conductivity gas detection device. This implementation is structurally similar to the above-described implementation, with the main difference being:

[0048] In this embodiment, the difference between the resistance of the first heating resistor Rj1 and the resistance of the first NTC thermistor is greater than the first preset value, indicating that the difference between the resistance of the first heating resistor Rj1 and the resistance of the first NTC thermistor is very large. In other words, the resistance of the first heating resistor Rj1 is much greater than the resistance of the first NTC thermistor.

[0049] Similarly, if the difference between the resistance of the second heating resistor Rj2 and the resistance of the second NTC thermistor is greater than the second preset value, it indicates that the difference between the resistance of the second heating resistor Rj2 and the resistance of the second NTC thermistor is large. In other words, the resistance of the second heating resistor Rj2 is much greater than the resistance of the second NTC thermistor. For example, the resistance of the first heating resistor Rj1 could be 10 times the resistance of the first NTC thermistor Rr1. 3 The resistance of the second heating resistor Rj1 can be 10 times the resistance of the second NTC thermistor Rr1. 3 times.

[0050] In this embodiment, the resistance of the first heating resistor Rj1 is much greater than the resistance of the first NTC thermistor, and the resistance of the second heating resistor Rj2 is much greater than the resistance of the second NTC thermistor. Therefore, the heat generated by the NTC thermistor itself can be ignored, thereby reducing the detection error caused by the characteristics of the NTC thermistor itself, and further improving the detection accuracy of the thermal conductivity gas detection device.

[0051] Another embodiment of this application provides an implementation of the first module 10, wherein the second output terminal of the first module 10 outputs the node voltage between the first thermistor Rr1 and the second thermistor Rr2; the first output terminal of the first module 10 outputs zero potential, that is, in this embodiment the first output terminal is ground GND, and the first input terminal of the feedback tracking module 20 is grounded GND as a reference potential.

[0052] Optionally, the grounding point is taken as a reference and its potential is defined as zero. The potential difference between other points and the reference point is called the voltage at that point. In this embodiment, the output terminal of the first module 10 outputs the potential difference corresponding to zero potential at point B in real time. The potential difference corresponding to zero potential at point B can reflect the voltage across the second thermistor Rr2. The voltage value of the voltage regulator 30 is known, and the voltage value of the voltage regulator 30 is equal to the sum of the voltages across the first and second thermistors. Therefore, by detecting the change in the potential difference corresponding to zero potential at point B, the ratio of the voltage across the second NTC thermistor to the voltage across the first NTC thermistor can be calculated and reflected.

[0053] Another embodiment of this application provides one implementation of the first module 10, the specific structure of which is as follows: Figure 1 or Figure 2 As shown, it specifically includes: a first resistor R1 and a second resistor R2. The first module 10 includes a first output terminal and a second output terminal, and the connection relationship between the components is as follows:

[0054] The resistance value of the first resistor R1 is equal to the resistance value of the second resistor R2. It is worth noting that in actual production, it is difficult to make the manufactured resistors exactly the same as the nominal resistance value; that is, the resistance value has a certain degree of variation. Therefore, when this article refers to the first resistor value being equal to the second resistor value, it means that their nominal resistance values ​​are the same, and deviations caused by manufacturing processes, etc., are allowed.

[0055] The first resistor R1 and the second resistor R2 are connected in series; the first output terminal A of the first module 10 is one end of the series connection between the first resistor R1 and the second resistor R2; the other end of the first resistor R1 is connected to the output terminal of the voltage regulator 30; the other end of the second resistor R2 is grounded.

[0056] The first NTC thermistor Rr1 and the second NTC thermistor Rr2 are connected in series; the second output terminal B of the first module 10 is one end of the second NTC thermistor Rr1 connected in series with the first NTC thermistor Rr1; the other end of the first NTC thermistor Rr1 is connected to the output terminal of the voltage regulator 30, and the other end of the second NTC thermistor Rr2 is grounded.

[0057] The detection principle of the first module 10 in this embodiment will be explained in detail below:

[0058] In this embodiment, initially, the ratio of the voltage across the second NTC thermistor Rr2 to the voltage across the first NTC thermistor Rr1 is 1. Specifically, the first output terminal A is the reference potential. In this embodiment, initially, the temperature of the detection cavity 02 is the same as the temperature of the reference cavity 01. The voltage output from the first output terminal A is the voltage across the first resistor R1. Since the resistance of the first resistor R1 is equal to the resistance of the second resistor R2, and the resistance of the second NTC thermistor Rr2 is equal to the resistance of the first NTC thermistor Rr1, the voltage division ratio of the second resistor R2 to the first resistor R1 is equal to the voltage division ratio of the second NTC thermistor Rr2 to the first NTC thermistor Rr1, both equal to 1. The voltage across the first resistor R1 and the voltage across the second thermistor Rr2 are both half the output voltage value of the regulated source 30. Since the other end of the second NTC thermistor Rr2 is grounded to GND and the other end of the second resistor R2 is grounded to GND, the potential of the second output terminal B of the first module 10 is equal to the potential of the first output terminal A. The potentials of the first input terminal and the second input terminal of the feedback tracking module 20 are equal. Therefore, the input of the feedback tracking module 20 is 0. At this time, the output voltage value of the feedback tracking module 20 is equal to the output voltage value of the voltage regulator 30.

[0059] Compared to the gas in the reference cavity 01, when a gas with lower thermal conductivity is mixed into the detection cavity 02, the temperature of the detection cavity 02 is higher than that of the reference cavity 01. In the first module 10, the resistance of the second NTC thermistor Rr2 is less than the resistance of the first NTC thermistor Rr1. Therefore, the ratio of the voltage across the second NTC thermistor Rr2 to the voltage across the first NTC thermistor Rr1 is less than 1, which is less than the ratio at the initial moment. Since the resistance of the first resistor R1 is still equal to the resistance of the second resistor R2, the voltage division ratio of the second resistor R2 to the first resistor R1 is still equal to 1, which can characterize the ratio of the voltage across the second NTC thermistor Rr2 to the voltage across the first NTC thermistor Rr1 at the initial moment. However, since the voltage division ratio of the second NTC thermistor Rr2 to the first NTC thermistor Rr1 is less than 1, the voltage across the second NTC thermistor Rr2 is less than the voltage across the first resistor R1. Since the other end of the second NTC thermistor Rr2 is grounded to GND and the other end of the second resistor R2 is grounded to GND, the potential of the second output terminal B of the first module 10 is less than the potential of the first output terminal A.

[0060] When the temperature of the detection chamber 02 is lower than the temperature of the reference chamber 01, the situation is the opposite of the above, and will not be repeated here.

[0061] As can be seen from the above, the potential difference between the second output terminal B and the first output terminal A of the first module 10 can characterize the change in the ratio of the voltage across the first NTC thermistor Rr1 to the voltage across the second NTC thermistor. Specifically, if the potential of the second output terminal B of the first module 10 is equal to the potential of the first output terminal A, it indicates that the voltage across the second NTC thermistor Rr2 is the same as the voltage across the first NTC thermistor Rr1, meaning the resistance of the second NTC thermistor Rr2 is the same as the resistance of the first NTC thermistor Rr1, and the temperature of the detection cavity 02 is the same as the temperature of the reference cavity 01. If the potential of the second output terminal B of the first module 10 is less than the potential of the first output terminal A, it indicates that the resistance of the second NTC thermistor Rr2 is less than the resistance of the first NTC thermistor Rr1, meaning the temperature of the detection cavity 02 is higher than the temperature of the reference cavity 01. If the potential of the second output terminal B of the first module 10 is greater than the potential of the first output terminal A, it indicates that the resistance of the second NTC thermistor Rr2 is greater than the resistance of the first NTC thermistor Rr1, meaning the temperature of the detection cavity 02 is lower than the temperature of the reference cavity 01.

[0062] In this embodiment, by Figure 1 or Figure 2It can be seen that the first resistor, the second resistor, the first NTC thermistor, and the second NTC thermistor constitute a Wheatstone bridge. Since the final temperature of the detection chamber is the same as the temperature of the reference chamber (i.e., the resistance values ​​of the first and second NTC thermistors are equal, and the resistance of the first resistor is equal to the resistance of the second resistor), the bridge is ultimately in a balanced state. This eliminates errors in the circuit, thereby improving the detection accuracy of the voltage difference between the two NTC thermistors. Consequently, the output voltage of the feedback tracking module 20 becomes more accurate, further enhancing the detection accuracy of the thermal conductivity gas detection device.

[0063] Another embodiment of this application provides another implementation of the first module 10, the specific structure of which is as follows: Figure 3 or Figure 4 (To simplify the view, Figure 3 or Figure 4 As shown in the diagram (excluding the reference cavity), it specifically includes: a first resistor R1 and a second resistor R2, a first heating resistor Rj1, a second heating resistor Rj2, a first thermistor Rr1, and a second thermistor Rr2. The connection relationships between the components are as follows:

[0064] The resistance of the first resistor R1 is equal to the resistance of the second resistor R2. Initially, the resistances of the first NTC thermistor Rr1 and the second NTC thermistor Rr2 are equal. That is, at the same operating temperature, the resistances of the first NTC thermistor Rr1 and the second NTC thermistor Rr2 are equal. Or, the product of the resistance of the first resistor R1 and the resistance of the second NTC thermistor Rr2 is equal to the product of the resistance of the second resistor R2 and the resistance of the first NTC thermistor Rr1.

[0065] The first resistor R1 and the first NTC thermistor Rr1 are connected in series; the first output terminal A of the first module 10 is one end of the first NTC thermistor Rr1 connected in series with the first resistor R1; the other end of the first resistor R1 is connected to the output terminal of the voltage regulator 30; the other end of the first NTC thermistor Rr1 is grounded to GND.

[0066] The second resistor R2 and the second NTC thermistor Rr2 are connected in series; the second output terminal B of the first module 10 is one end of the second NTC thermistor Rr2 connected in series with the second resistor R2; the other end of the second resistor R2 is connected to the output terminal of the voltage regulator 30; the other end of the second NTC thermistor Rr2 is grounded to GND.

[0067] One end of the first heating resistor Rj1 is connected to the output terminal of the voltage regulator 30, and the other end of the first heating resistor Rj1 is grounded to GND; the first heating resistor Rj1 and the first thermistor Rr1 are located in the reference cavity.

[0068] One end of the second heating resistor Rj2 is connected to the output terminal of the feedback tracking module 20, and the other end of the second heating resistor Rj2 is grounded to GND; the second heating resistor Rj2 and the second thermistor Rr2 are located in the detection cavity.

[0069] The detection principle of the first module 10 is explained in detail below:

[0070] Initially, when the temperature of the detection cavity 02 is the same as the temperature of the reference cavity 01, that is, when the resistance of the second NTC thermistor Rr2 is the same as the resistance of the first NTC thermistor Rr1, since the resistance of the first resistor R1 is equal to the resistance of the second resistor R2, the voltage division ratio of the second resistor R2 and the second NTC thermistor Rr2 is equal to the voltage division ratio of the first resistor R1 and the first NTC thermistor Rr1. Therefore, the voltage across the second NTC thermistor Rr2 is equal to the voltage across the first NTC thermistor Rr1, and the ratio of the voltage across the second NTC thermistor Rr2 to the voltage across the first NTC thermistor Rr1 is equal to 1. If, at the initial moment, the product of the resistance of the first resistor R1 and the second NTC thermistor Rr2 is equal to the product of the second resistor R2 and the first NTC thermistor Rr1, then the ratio of the voltage across the second NTC thermistor Rr2 to the voltage across the first NTC thermistor Rr1 at the initial moment is set to be X.

[0071] Since the other end of the first NTC thermistor Rr1 is grounded to GND and the other end of the second NTC thermistor Rr2 is grounded to GND, the potential of the second output terminal B of the first module 10 is equal to the potential of the first output terminal A.

[0072] When the temperature of the detection cavity 02 is higher than the temperature of the reference cavity 01, that is, when the resistance of the second NTC thermistor Rr2 is less than the resistance of the first NTC thermistor Rr1, since the resistance of the first resistor R1 is equal to the resistance of the second resistor R2, the voltage division ratio of the second NTC thermistor Rr2 to the first resistor R2 is less than the voltage division ratio of the first NTC thermistor Rr1 to the first resistor R1. Therefore, the voltage across the second NTC thermistor Rr2 is less than the voltage across the first NTC thermistor Rr1, and the ratio of the voltage across the second NTC thermistor Rr2 to the voltage across the first NTC thermistor Rr1 decreases. Furthermore, since the other end of the first NTC thermistor Rr1 is grounded to GND and the other end of the second NTC thermistor Rr2 is grounded to GND, the potential of the second output terminal B of the first module 10 is less than the potential of the first output terminal A.

[0073] When the temperature of the detection chamber 02 is lower than the temperature of the reference chamber 01, the situation is the opposite of the above, and will not be repeated here.

[0074] As described above, the potential of the second output terminal B of the first module 10 is the voltage across the second NTC thermistor Rr2, and the potential of the first output terminal A of the first module 10 is the voltage across the first NTC thermistor Rr1. Therefore, the first module 10 can obtain the ratio of the voltage across the second NTC thermistor Rr2 to the voltage across the first NTC thermistor Rr1. With this setting, the voltage values ​​of the first output terminal A and the second output terminal B are directly the voltage values ​​across the first NTC thermistor Rr1 and the second NTC thermistor Rr2, without conversion, rather than a ratio or difference between the two. This allows for a more accurate reflection of the dynamic changes in the voltage across the second NTC thermistor Rr2. Specifically, if the potential of the second output terminal B of the first module 10 is equal to the potential of the first output terminal A, it indicates that the resistance of the second NTC thermistor Rr2 is the same as the resistance of the first NTC thermistor Rr1, meaning that the temperature of the detection cavity 02 is the same as the temperature of the reference cavity 01; if the potential of the second output terminal B of the first module 10 is less than the potential of the first output terminal A, it indicates that the resistance of the second NTC thermistor Rr2 is less than the resistance of the first NTC thermistor Rr1, meaning that the temperature of the detection cavity 02 is higher than the temperature of the reference cavity 01; if the potential of the second output terminal B of the first module 10 is greater than the potential of the first output terminal A, it indicates that the resistance of the second NTC thermistor Rr2 is greater than the resistance of the first NTC thermistor Rr1, meaning that the temperature of the detection cavity 02 is lower than the temperature of the reference cavity 01.

[0075] In this embodiment, by Figure 3 or Figure 4 It can be seen that the first resistor, the second resistor, the first NTC thermistor, and the second NTC thermistor constitute a Wheatstone bridge. Since the final temperature of the detection chamber is the same as the temperature of the reference chamber (i.e., the resistance values ​​of the first and second NTC thermistors are equal, and the resistance of the first resistor is equal to the resistance of the second resistor), the bridge is ultimately in a balanced state. This eliminates errors in the circuit and improves the accuracy of resistance detection for the two NTC thermistors. Because the accuracy of resistance detection for the two NTC thermistors is improved, the output voltage of the feedback tracking module 20 becomes more precise, further enhancing the detection accuracy of the thermal conductivity gas detection device.

[0076] Another embodiment of this application provides yet another implementation of the first module 10, which is similar to... Figure 3 or Figure 4 The structure of the first module 10 shown is largely the same, and will not be described again here. This embodiment is similar to... Figure 3 or Figure 4 The main difference in the implementation of the first module 10 shown is that:

[0077] Both the first resistor R1 and the second resistor R2 are precision resistors.

[0078] Since it is easy to control the error of the precision resistor to within 1%, this allows for higher accuracy in the resistance values ​​of the first NTC thermistor Rr1 and the second NTC thermistor Rr2 detected by the first module 10, thereby further improving the detection accuracy of the thermal conductivity gas detection device.

[0079] The above example only illustrates one specific implementation of the first resistor R1 and the second resistor R1. In practical applications, there are other implementations, including but not limited to this one. No specific limitation is made here. The implementation can be determined according to the specific circumstances, and all are within the protection scope of this application.

[0080] Another embodiment of this application provides an implementation of the feedback tracking module 20, which is applicable to: the first module 10 adopting Figures 1-4 The implementation method is shown in any one of the figures. (Refer to...) Figure 1 The thermal conductivity gas detection device includes an input power supply circuit, which includes an input power supply Vin. The feedback tracking module 20 specifically includes a differential proportional operation circuit 21 and a first transistor 22. The connection relationships between the components are as follows:

[0081] The non-inverting input of the differential proportional operation circuit 21 serves as the first input of the feedback tracking module 20 and is connected to the second output B of the first module 10. The inverting input of the differential proportional operation circuit 21 serves as the second input of the feedback tracking module 20 and is connected to the first output A of the first module 10.

[0082] The output of the differential proportional operation circuit is connected to the base of the first transistor 22, the collector of the first transistor 22 is connected to the output of the input power supply Vin, and the emitter of the first transistor 22 serves as the output of the feedback tracking module 20; the first transistor is an N-type transistor.

[0083] The output voltage of the differential proportional operational circuit 21 is initially equal to the output voltage of the voltage regulator 30 plus the voltage difference between the base and emitter of the first transistor. Initially, the output voltage of the emitter of the first transistor is equal to the output voltage of the voltage regulator 30.

[0084] If the resistance of the second NTC thermistor Rr2 decreases, the resistance difference between the second NTC thermistor Rr2 and the first NTC thermistor Rr1 decreases. That is, the potential difference between the non-inverting input terminal and the inverting input terminal of the differential proportional operation circuit 21 decreases. As a result, after being amplified by the differential proportional operation circuit 21, the output voltage of the differential proportional operation circuit 21 decreases even more. Consequently, the voltage between the control terminal and the output terminal of the first transistor 22 also decreases. That is, the voltage across the second heating resistor Rj2 decreases. Therefore, the heating power of the second heating resistor Rj2 decreases, and the temperature of the detection cavity 02 drops.

[0085] If the resistance of the second NTC thermistor Rr2 increases, the resistance difference between the second NTC thermistor Rr2 and the first NTC thermistor Rr1 increases. That is, the potential difference between the non-inverting input terminal and the inverting input terminal of the differential proportional operation circuit 21 increases. As a result, after being amplified by the differential proportional operation circuit 21, the output voltage of the differential proportional operation circuit 21 increases even more. Consequently, the voltage between the control terminal and the output terminal of the first transistor 22 also increases. That is, the voltage across the second heating resistor Rj2 increases. Therefore, the heating power of the second heating resistor Rj2 increases, and the temperature of the detection cavity 02 rises.

[0086] The output potential of the differential proportional operational circuit 21 at the initial moment is equal to the output voltage of the voltage regulator 30 plus the voltage difference between the base and emitter of the first transistor 22. Since the base potential of the first transistor 22 is normally equal to the emitter potential plus the voltage difference between the base and emitter, initially, the emitter potential of the first transistor 22 is equal to the output voltage of the voltage regulator 30. That is, initially, the output voltage of the feedback tracking module 20 is equal to the output voltage of the voltage regulator 30.

[0087] The above is only one specific implementation of the feedback tracking module 20. In practical applications, it includes, but is not limited to, this one. It can be determined according to the specific situation and is within the protection scope of this application.

[0088] Another embodiment of this application provides a specific implementation of the differential proportional operation circuit 21, which can be referred to... Figure 1 Specifically, this includes: resistor R3, resistor R4, resistor R5, resistor R6, and operational amplifier 211. The connection relationships between these components are as follows:

[0089] The non-inverting input of operational amplifier 211 is connected to one end of the third resistor R3, and the other end of the third resistor R3 serves as the non-inverting input of differential proportional operational circuit 21. The other end of the third resistor R3 is connected to point B, the second output of the first module 10.

[0090] The non-inverting input of operational amplifier 211 is also connected to one end of the fourth resistor R4, and the node voltage at the other end of the fourth resistor R4 is equal to the output voltage of the voltage regulator 30.

[0091] Under normal circumstances, the potential of the base of the first transistor 22 is equal to the potential of the emitter of the first transistor 22 plus the voltage difference between the base and emitter of the first transistor 22. Initially, the potential of the emitter of the first transistor 22 is equal to the output voltage of the voltage regulator 30. That is, initially, the voltage value output by the feedback tracking module 20 is equal to the output voltage value of the voltage regulator 30.

[0092] For details, please refer to Figure 2 When the potentials of the first output terminal A and the second output terminal B are equal, that is, the input voltage of the operational amplifier 211 is 0, and the output voltage is determined by the potential of the upper end of the fourth resistor R4, in a specific embodiment, the input power supply circuit includes an input power supply Vin, a current-limiting resistor Rx2, and a first diode D1. The input power supply Vin, the current-limiting resistor Rx2, the first diode D1, and the voltage regulator 30 are connected in sequence. At this time, the potential of the node between the first diode D1 and the current-limiting resistor Rx2 is equal to the sum of the output voltage of the voltage regulator 30 and the voltage of the first diode D1. Since the voltage of the first diode D1 is equal to the voltage difference between the base and emitter of the first transistor 22, the emitter output potential of the first transistor 22 is equal to the output voltage of the voltage regulator 30. Therefore, the voltage across the second heating resistor Rj2 is equal to the output voltage of the voltage regulator 30. The voltages across the second heating resistor Rj2 and the first heating resistor Rj1 are equal, and their resistances are equal, so their heating power is equal. Under the same heat dissipation conditions in a certain atmospheric environment, the temperature of the detection cavity and the reference cavity are the same. It is worth noting that as long as the upper end potential of the fourth resistor R4 is equal to the sum of the output voltage of the voltage regulator 30 and the voltage across a diode, and the emitter output voltage of the first transistor 22 is equal to the output voltage of the voltage regulator 30, the requirements of this technical solution are met.

[0093] The inverting input of operational amplifier 211 is connected to one end of the fifth resistor R5, and the other end of the fifth resistor R5 serves as the inverting input of the differential proportional operational circuit 21. The other end of the fifth resistor R5 is connected to the first output terminal A of the first module 10.

[0094] The inverting input of operational amplifier 211 is also connected to one end of the sixth resistor R6, and the other end of the sixth resistor R6 is connected to the output of operational amplifier 211. The output of operational amplifier 211 serves as the output of differential proportional operational circuit 21.

[0095] As can be seen from the connection relationship of the differential proportional operational circuit 21, if the non-inverting input terminal of the operational amplifier 211 is also connected to one end of the fourth resistor R4, and the node voltage at the other end of the fourth resistor R4 is equal to the output voltage of the voltage regulator 30, at the initial moment, the potential at the output terminal of the operational amplifier 211 is equal to the output voltage of the voltage regulator 30 plus the voltage difference between the base and emitter of the first transistor 22. Therefore, at the initial moment, the potential at the output terminal of the differential proportional operational circuit 21 is equal to the output voltage of the voltage regulator 30 plus the voltage difference between the base and emitter of the first transistor 22.

[0096] It should be noted that how the node voltage at the other end of the fourth resistor R4 is equal to the output voltage of the voltage regulator 30 will be explained in detail in the following embodiments in conjunction with the implementation of the voltage regulator 30, and will not be repeated here.

[0097] Another embodiment of this application provides a specific implementation of the voltage regulator 30, which is applicable to situations where the regulator itself is a voltage regulator 30. The specific structure of this implementation is as follows: Figure 1 or Figure 3 As shown in Figure 30, it specifically includes: the first voltage regulator ZD1, the seventh resistor, and the eighth resistor. The connection relationships between the components are as follows:

[0098] The anode of the first voltage regulator ZD1 is grounded, and the cathode of the first voltage regulator ZD1 serves as the output terminal of the regulated source 30. The seventh resistor R7 and the eighth resistor R8 are connected in series. One end of the seventh resistor R7 connected in series with the eighth resistor R8 is connected to the control terminal of the first voltage regulator ZD1. The other end of the seventh resistor R7 is connected to the anode of the first voltage regulator ZD1, and the other end of the eighth resistor R8 is connected to the cathode of the first voltage regulator ZD1. By adjusting the resistance value of the seventh resistor R7 or the eighth resistor R8, the output voltage of the first voltage regulator ZD1 can be adjusted.

[0099] If the differential proportional operation circuit 21 adopts as follows Figures 1-4 In the embodiment shown, the non-inverting input terminal of the operational amplifier 211 in the differential proportional operational circuit 21 is connected to the cathode of the first voltage regulator ZD1 through the fourth resistor R4. Alternatively, the non-inverting input terminal of the operational amplifier 211 in the differential proportional operational circuit 21 is connected to the anode of the first diode D1 through the fourth resistor R4, and the cathode of the first diode D1 is connected to the cathode of the first voltage regulator ZD1.

[0100] Since the cathode of the first voltage regulator ZD1 serves as the output terminal of the voltage regulator 30, if the non-inverting input terminal of the operational amplifier 211 in the differential proportional operational circuit 21 is connected to the cathode of the first voltage regulator ZD1 through the fourth resistor R4, the set voltage is equal to the output voltage of the voltage regulator 30.

[0101] Since the non-inverting input of the operational amplifier 211 in the differential proportional operational circuit 21 is connected to the anode of the first diode D1 through the fourth resistor R4, and the cathode of the first diode D1 is connected to the cathode of the first voltage regulator ZD1, and the cathode of the first voltage regulator ZD1 serves as the output terminal of the voltage regulator 30, the potential of the anode of the first diode D1 is equal to the output voltage of the voltage regulator 30 plus the voltage drop of the first diode D1. Therefore, the set voltage is equal to the output voltage of the voltage regulator 30 plus the voltage drop of the first diode D1. Furthermore, since the voltage drop of a diode is usually approximately equal to the voltage difference between the base and emitter of a transistor, the set voltage is equal to the output voltage of the voltage regulator 30 plus the voltage difference between the base and emitter of the first transistor 22.

[0102] If the feedback tracking module 20 adopts the following... Figures 1-4 In the embodiment shown, the anode of the first diode D1 is also connected to the output terminal of the input power supply Vin through the first current-limiting resistor Rx1.

[0103] The above is only one specific embodiment of the voltage regulator 30. In practical applications, there are other embodiments, including but not limited to this one. No specific limitation is made here, and all are within the protection scope of this application.

[0104] Another embodiment of this application provides another specific implementation of the voltage regulator 30, which is applicable to situations where the regulator itself is the voltage regulator 30. The specific structure of this implementation is as follows: Figure 2 or Figure 4 As shown in Figure 30, it specifically includes: a second transistor 31, a second voltage regulator ZD2, a first resistor branch 32, and a second resistor branch 33. The connection relationships between the components are as follows:

[0105] The anode of the second voltage regulator ZD2 is grounded, the cathode of the second voltage regulator ZD2 is connected to the base of the second transistor 31, the collector of the second transistor 31 is connected to the output terminal of the input power supply circuit, and the emitter of the second transistor 31 serves as the output terminal of the voltage regulator 30. The second transistor 31 is an N-type transistor.

[0106] The first resistor branch 32 is connected in series with the second resistor branch 33. The end of the first resistor branch 32 connected in series with the second resistor branch 33 is connected to the control terminal of the second voltage regulator ZD2.

[0107] The other end of the first resistor branch 32 is connected to the anode of the second voltage regulator ZD2, and the other end of the second resistor branch 33 is connected to the emitter of the second transistor 31. The output voltage of the second voltage regulator ZD2 can be adjusted by adjusting the resistance value of the first resistor branch 32 or the second resistor branch 33.

[0108] If the differential proportional operation circuit 21 adopts as follows Figures 1-4In the embodiment shown, the non-inverting input terminal of the operational amplifier 211 in the differential proportional operational circuit 21 is connected to the cathode of the second voltage regulator ZD2 through the fourth resistor R4, and the second transistor 31 and the first transistor 22 are the same type of device.

[0109] Since the cathode of the second voltage regulator ZD2 is connected to the base of the second transistor 31, and the emitter of the second transistor 31 serves as the output terminal of the voltage regulator 30, the output voltage of the second voltage regulator ZD2 is equal to the output voltage of the voltage regulator 30 plus the voltage difference between the base and emitter of the second transistor 31. Therefore, the voltage is set to be equal to the output voltage of the voltage regulator 30 plus the voltage difference between the base and emitter of the second transistor 31. Furthermore, since the second transistor 31 and the first transistor 22 use the same type of device, the voltage difference between the base and emitter of the second transistor 31 is equal to the voltage difference between the base and emitter of the first transistor 22. Therefore, the voltage is set to be equal to the output voltage of the voltage regulator 30 plus the voltage difference between the base and emitter of the first transistor 22.

[0110] If the feedback tracking module 20 adopts the following... Figures 1-4 In the embodiment shown, the cathode of the second voltage regulator ZD2 is also connected to the output terminal of the input power supply Vin through the second current-limiting resistor Rx2.

[0111] The above is only one specific embodiment of the voltage regulator 30. In practical applications, there are other embodiments, including but not limited to this one. No specific limitation is made here, and all are within the protection scope of this application.

[0112] Another embodiment of this application provides a specific implementation of a resistor branch, applicable to both the first resistor branch 32 and the second resistor branch 33. The specific structure of this embodiment is as follows: Figure 2 , Figure 4 32, 33 or Figure 7 As shown in 32, it specifically includes: the tenth resistor R10; the two ends of the tenth resistor R10 serve as the two ends of the resistor branch.

[0113] The above is only one specific implementation of the resistor branch. In practical applications, there are other implementations, including but not limited to this one. No specific limitation is made here, and all are within the protection scope of this application.

[0114] Another embodiment of this application provides a specific implementation of a resistor branch, applicable to both the first resistor branch 32 and the second resistor branch 33. The specific structure of this embodiment is as follows: Figure 5 As shown, this specifically includes at least two ninth resistors R9 and at least one switching transistor 321. The connection relationships between the devices are described in detail below:

[0115] Each of the ninth resistors R9 is connected in series, and the two ends of the series branch are respectively used as the two ends of the corresponding resistor branch.

[0116] The series terminals of any two ninth resistors R9 are connected to the input terminals of the corresponding switching transistors 321; the output terminals of each switching transistor 321 are grounded to GND.

[0117] All switching transistors 321 are controlled to turn on and off. By controlling the conduction of different switching transistors 321, the total resistance of the resistor branch is adjusted, thereby adjusting the output voltage of the second voltage regulator ZD2. For example, with... Figure 7 Taking the first resistor branch 32 as an example, if all the switching transistors 321 are turned off, the total resistance of the first resistor branch 32 is equal to the sum of the resistances of the four ninth resistors R9; if only the first switching transistor 321 from right to left is turned on, the total resistance of the first resistor branch 32 is equal to the sum of the resistances of the three ninth resistors R9; if only the second switching transistor 321 from right to left is turned on, the total resistance of the first resistor branch 32 is equal to the sum of the resistances of the two ninth resistors R9; if the third switching transistor 321 from right to left is turned on, the total resistance of the first resistor branch 32 is equal to the resistance of the one ninth resistor R9.

[0118] Optionally, each switch 321 can be a MOSFET or a transistor. In practical applications, there are other types of transistors, including but not limited to these. No specific limitation is made here, and all are within the scope of protection of this application.

[0119] In this embodiment, since each switch 321 is controlled by the controller in actual application, this embodiment can adjust the total resistance of the resistor branch, thereby adjusting the output voltage of the second voltage regulator ZD2, and further adjusting the heating power of the first heating resistor Rj1. If the resistance of each ninth resistor R9 is small, the heating power of the first heating resistor Rj1 can be fine-tuned.

[0120] The above is only one specific implementation of the resistor branch. In practical applications, there are other implementations, including but not limited to this one. No specific limitation is made here, and all are within the protection scope of this application.

[0121] To further improve detection accuracy, another embodiment of this application provides another implementation of the thermal conductivity gas detection device. This implementation, based on the above implementation, further includes: a first heat-conducting element disposed in the reference cavity and a second heat-conducting element disposed in the detection cavity.

[0122] The first NTC thermistor and the first heating resistor Rj1 are disposed in the first heat-conducting component so that the temperature collected by the first NTC thermistor Rr1 is the temperature of the first heating resistor Rj1.

[0123] In a specific example, such as Figure 5 As shown, the first heat-conducting component is the first heat-conducting pipe, and the first NTC thermistor Rr1 and the first heating resistor Rj1 are inserted into the first heat-conducting pipe in a head-to-head manner.

[0124] In another specific example, such as Figure 6 As shown, the first heat-conducting component is the first heat-conducting base, and the first NTC thermistor Rr1 and the first heating resistor Rj1 are inserted into the first heat-conducting base in a side-by-side manner.

[0125] The two examples above only illustrate two specific implementations of achieving the temperature of the first NTC thermistor Rr1 being the temperature of the first heating resistor Rj1. In practical applications, there are other implementations, including but not limited to these. No specific limitation is made here. The implementation can be determined according to the specific circumstances, and all are within the protection scope of this application.

[0126] The second NTC thermistor and the second heating resistor Rj2 are disposed in the second heat-conducting component so that the temperature collected by the second NTC thermistor Rr2 is the temperature of the second heating resistor Rj2.

[0127] In a specific example, the second heat-conducting element is a second heat-conducting pipe, and the second NTC thermistor Rr2 and the second heating resistor Rj2 are inserted into the second heat-conducting pipe in a head-to-head manner.

[0128] In another specific example, the second heat-conducting element is a second heat-conducting base, and the second NTC thermistor Rr2 and the second heating resistor Rj2 are inserted into the second heat-conducting base in a side-by-side manner.

[0129] It should be noted that the two specific implementations shown in the above examples for achieving the temperature of the second NTC thermistor Rr2 equal to the temperature of the second heating resistor Rj2 are the same as the two specific implementations for achieving the temperature of the first NTC thermistor Rr1 equal to the temperature of the first heating resistor Rj1. Therefore, they will not be illustrated here, but please refer to the corresponding figures of the above implementations.

[0130] The two examples above only demonstrate two specific implementations of achieving the temperature of the second NTC thermistor Rr2 being the temperature of the second heating resistor Rj2. In practical applications, there are other implementations, including but not limited to these, which are not specifically limited here and can be determined according to the specific circumstances, and all are within the protection scope of this application.

[0131] In this embodiment, the temperature collected by the first NTC thermistor Rr1 is the surface temperature of the first heating resistor Rj1, and the temperature collected by the second NTC thermistor Rr2 is the surface temperature of the second heating resistor Rj2. Therefore, the temperatures collected by the first NTC thermistor Rr1 and the second NTC thermistor are more accurate, minimizing heat loss in the detection chamber due to gas convection. This more accurately reflects the heat loss caused by gas thermal conduction on the surface temperature of the first heating resistor Rj1. Furthermore, when the temperature of the reference chamber and the detection chamber are the same after adjustment, the output voltage value of the feedback tracking module 20 is more accurate. At the same time, it reduces the detection error caused by the different operating temperatures of the NTC thermistors, thereby further improving the detection accuracy of the thermal conductivity gas detection device.

[0132] This application also provides a thermally conductive gas detection device, comprising: a voltage regulator 30, a first module 10, a feedback tracking module 20, a first heating resistor Rj1, and a second heating resistor Rj2; wherein:

[0133] The first module 10 includes a first NTC thermistor Rr1 and a second NTC thermistor Rr2;

[0134] The first heating resistor Rj1 is set in the reference cavity. One end of the first heating resistor Rj1 is connected to the output terminal of the voltage regulator 30, and the other end of the first heating resistor Rj1 is grounded. The first NTC thermistor Rr1 is set in the reference cavity.

[0135] The second heating resistor Rj2 is set in the detection cavity. One end of the second heating resistor Rj2 is connected to the output terminal of the feedback tracking module 20, and the other end of the second heating resistor Rj2 is grounded. The second NTC thermistor Rr2 is set in the detection cavity.

[0136] The resistance value of the first heating resistor Rj1 is equal to the resistance value of the second heating resistor Rj2; the output terminal of the first module 10 is connected to the feedback tracking module 20;

[0137] The output of the first module 10 can be used to obtain the ratio of the voltage across the second NTC thermistor Rr2 to the voltage across the first NTC thermistor Rr1. The initial ratio of the voltage across the second NTC thermistor Rr2 to the voltage across the first NTC thermistor Rr1 is defined as X. The initial voltage output of the feedback tracking module 20 is equal to the output voltage of the voltage regulator 30. The feedback tracking module 20 can adjust its output voltage accordingly when the ratio of the voltage across the second NTC thermistor Rr2 to the voltage across the first NTC thermistor Rr1 changes compared to the initial ratio X.

[0138] Assuming the thermal conductivity of the gas in the detection chamber and the reference chamber is the same at the initial moment, the voltage across the first heating resistor Rj1 is equal to the output voltage of the regulated source 30, and the voltage across the second heating resistor Rj2 is equal to the output voltage of the feedback tracking module 20. Since the output voltage of the feedback tracking module 20 is equal to the output voltage of the regulated source 30 at the initial moment, and the resistance of the first heating resistor Rj1 is equal to that of the second heating resistor Rj2, the heating power of the first heating resistor Rj1 and the second heating resistor Rj2 is equal. Therefore, under a fixed heat dissipation condition in standard atmosphere, excluding other influencing factors, and only determined by the heating power of the first heating resistor Rj1 and the second heating resistor Rj2, the temperature of the detection chamber is the same as that of the reference chamber at the initial moment. The ratio of the voltage across the first thermistor and the voltage across the second thermistor at the initial moment is set to X. If a gas with poor thermal conductivity enters the detection chamber, the temperature of the detection chamber will rise, and the resistance of the second NTC thermistor will decrease. That is, the ratio of the voltage across the second NTC thermistor to the voltage across the first NTC thermistor will decrease. This causes the feedback tracking module 20 to reduce its own output voltage, reducing the heating power of the second heating resistor Rj2, and further lowering the temperature of the detection chamber. This cycle repeats until the ratio of the voltage across the first thermistor to the voltage across the second thermistor equals the initial ratio X. If a gas with high thermal conductivity enters the detection chamber, the adjustment process is the reverse of the above process, which will not be elaborated here. As can be seen from the above, the change in the output voltage of the feedback tracking module 20 will vary depending on the concentration of the gas entering the detection chamber. Therefore, the concentration of the gas entering the detection chamber can be detected by utilizing the change in the output voltage of the feedback tracking module 20. Since the temperature of the final detection chamber is the same as that of the reference chamber during the above adjustment process, the heat generated by the two NTC thermistors is the same, thereby reducing the difference between the resistance values ​​of the two NTC thermistors, and further reducing the deviation of the output voltage of the feedback tracking module 20, thus improving the detection accuracy of the thermal conductivity gas detection device.

[0139] The above description of the technical solutions in the disclosed embodiments shows that the features described in the various embodiments of this specification can be substituted for or combined with each other, enabling those skilled in the art to easily implement or use this application. The above descriptions are merely some embodiments of the present invention, not all embodiments, and are not intended to limit the present invention in any way.

Claims

1. A thermal conductivity type gas detection device, characterized in that, include: Regulated power supply, first module, feedback tracking module, first heating resistor, second heating resistor; wherein: The first module includes a first NTC thermistor and a second NTC thermistor; The first heating resistor is disposed in the reference cavity, one end of the first heating resistor is connected to the output terminal of the voltage regulator, and the other end of the first heating resistor is grounded. The first NTC thermistor is disposed in the reference cavity. The second heating resistor is disposed in the detection cavity. One end of the second heating resistor is connected to the output terminal of the feedback tracking module, and the other end of the second heating resistor is grounded. The second NTC thermistor is disposed in the detection cavity. The resistance of the first heating resistor is equal to the resistance of the second heating resistor; the output terminal of the first module is connected to the input terminal of the feedback tracking module; The feedback tracking module can output a variable voltage.

2. The thermal conductivity gas detection device according to claim 1, characterized in that, The first module includes a first output terminal and a second output terminal; the feedback tracking module includes a first input terminal and a second input terminal; the first output terminal of the first module is connected to the first input terminal of the feedback tracking module, and the second output terminal of the first module is connected to the second input terminal of the feedback tracking module. The first NTC thermistor and the second NTC thermistor are connected in series; the first output terminal of the first module is grounded, the second output terminal of the first module is connected to the series terminal of the second NTC thermistor, the other end of the first NTC thermistor is connected to the output terminal of the voltage regulator, and the other end of the second NTC thermistor is grounded.

3. The thermal conductivity gas detection device according to claim 1, characterized in that, The first module includes a first resistor and a second resistor; the first resistor and the second resistor have equal resistance values; wherein: the first module includes a first output terminal and a second output terminal; the feedback tracking module includes a first input terminal and a second input terminal; the first output terminal of the first module is connected to the first input terminal of the feedback tracking module, and the second output terminal of the first module is connected to the second input terminal of the feedback tracking module; The first resistor and the second resistor are connected in series; the series terminal of the second resistor is the first output terminal of the first module, and the other end of the first resistor is connected to the output terminal of the voltage regulator; the other end of the second resistor is grounded; the first NTC thermistor and the second NTC thermistor are connected in series; the series terminal of the second NTC thermistor is the second output terminal of the first module; the other end of the first NTC thermistor is connected to the output terminal of the voltage regulator, and the other end of the second NTC thermistor is grounded; Alternatively, the first resistor and the first NTC thermistor are connected in series; the series terminal of the first NTC thermistor is the first output terminal of the first module; the other end of the first resistor is connected to the output terminal of the voltage regulator; the other end of the first NTC thermistor is grounded; the second resistor and the second NTC thermistor are connected in series, the series terminal of the second NTC thermistor is the second output terminal of the first module; the other end of the second resistor is connected to the output terminal of the voltage regulator; the other end of the second NTC thermistor is grounded.

4. The thermal conductivity gas detection device according to claim 3, characterized in that, The thermal conductivity gas detection device includes an input power supply circuit, and the feedback tracking module includes a differential proportional operation circuit and a first transistor; wherein: The non-inverting input terminal of the differential proportional operation circuit serves as the first input terminal of the feedback tracking module, and the inverting input terminal of the differential proportional operation circuit serves as the second input terminal of the feedback tracking module. The output terminal of the differential proportional operation circuit is connected to the base of the first transistor, the collector of the first transistor is connected to the output terminal of the input power supply circuit, and the emitter of the first transistor serves as the output terminal of the feedback tracking module; the first transistor is an N-type transistor. The output potential of the differential proportional operational circuit at the initial moment is equal to the output voltage of the voltage regulator plus the voltage difference between the base and emitter of the first transistor.

5. The thermal conductivity gas detection device according to claim 4, characterized in that, The differential proportional operational circuit includes: a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, and an operational amplifier; wherein: The non-inverting input terminal of the operational amplifier is connected to one end of the third resistor, and the other end of the third resistor serves as the non-inverting input terminal of the differential proportional operational circuit. The non-inverting input terminal of the operational amplifier is also connected to one end of the fourth resistor, the other end of the fourth resistor has a potential equal to the output voltage of the voltage regulator, and the other end of the fourth resistor is connected to the output terminal of the input power supply circuit. The inverting input terminal of the operational amplifier is connected to one end of the fifth resistor, and the other end of the fifth resistor serves as the inverting input terminal of the differential proportional operational circuit. The inverting input terminal of the operational amplifier is also connected to one end of the sixth resistor, and the other end of the sixth resistor is connected to the output terminal of the operational amplifier. The output terminal of the operational amplifier serves as the output terminal of the differential proportional operational circuit.

6. The thermal conductivity gas detection device according to any one of claims 1-5, characterized in that, The ratio of the resistance of the first heating resistor to the resistance of the first NTC thermistor is greater than or equal to 10. 3 And / or, the ratio of the resistance of the second heating resistor to the resistance of the second NTC thermistor is greater than or equal to 10. 3 ; The voltage regulator includes: a first voltage regulator, a seventh resistor, and an eighth resistor; The anode of the first voltage regulator is grounded, and the cathode of the first voltage regulator serves as the output terminal of the voltage source. One end of the seventh resistor is connected to the control terminal of the first voltage regulator; one end of the eighth resistor is connected to the control terminal of the first voltage regulator; the seventh resistor and the eighth resistor are connected in series; The other end of the seventh resistor is connected to the anode of the first voltage regulator, and the other end of the eighth resistor is connected to the cathode of the first voltage regulator.

7. The thermal conductivity gas detection device according to any one of claims 1-5, characterized in that, Includes an input power supply circuit; the voltage regulator includes a second transistor, a second voltage regulator, a first resistor branch, and a second resistor branch; wherein: The anode of the second voltage regulator is grounded, the cathode of the second voltage regulator is connected to the base of the second transistor, the collector of the second transistor is connected to the output terminal of the input power supply circuit, and the emitter of the second transistor serves as the output terminal of the voltage regulator. The second transistor is an N-type transistor; The control terminal of the second voltage regulator is connected to one end of the first resistor branch, and the control terminal of the second voltage regulator is connected to one end of the second resistor branch; The other end of the first resistor branch is connected to the anode of the second voltage regulator, and the other end of the second resistor branch is connected to the emitter of the second transistor.

8. The thermal conductivity gas detection device according to claim 7, characterized in that, In at least one resistor branch, each resistor branch includes: at least two ninth resistors and at least one switching transistor; Each of the ninth resistors is connected in series, with the two ends of the series branch serving as the two ends of the corresponding resistor branch; the series terminals of any two ninth resistors are connected to the input terminal of the corresponding switch transistor; the output terminal of each switch transistor is grounded; all switches transistors are controlled to be switched on and off. or, Each resistor branch includes: a tenth resistor; the two ends of the tenth resistor serve as the two ends of the resistor branch.

9. The thermal conductivity gas detection device according to any one of claims 1 to 5, characterized in that, It also includes a first heat-conducting element and a second heat-conducting element; the first heat-conducting element is disposed in the reference cavity, and the second heat-conducting element is disposed in the detection cavity; wherein: The first NTC thermistor and the first heating resistor are connected to the first heat-conducting component; The second NTC thermistor and the second heating resistor are connected to the second heat-conducting component.

10. A thermal conductivity type gas detection device, characterized in that, include: Regulated power supply, first module, feedback tracking module, first heating resistor, second heating resistor; wherein: The first module includes a first NTC thermistor and a second NTC thermistor; The first heating resistor is disposed in the reference cavity, one end of the first heating resistor is connected to the output terminal of the voltage regulator, and the other end of the first heating resistor is grounded. The first NTC thermistor is disposed in the reference cavity. The second heating resistor is disposed in the detection cavity. One end of the second heating resistor is connected to the output terminal of the feedback tracking module, and the other end of the second heating resistor is grounded. The second NTC thermistor is disposed in the detection cavity. The resistance of the first heating resistor is equal to the resistance of the second heating resistor; the output terminal of the first module is connected to the feedback tracking module; The output of the first module can be used to obtain the ratio of the voltage across the second NTC thermistor to the voltage across the first NTC thermistor. The initial ratio of the voltage across the second NTC thermistor to the voltage across the first NTC thermistor is defined as X. The initial voltage value output by the feedback tracking module is equal to the output voltage value of the regulated source. The feedback tracking module can adjust its output voltage accordingly when the ratio of the voltage across the second NTC thermistor to the voltage across the first NTC thermistor changes compared to the initial ratio X.

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