An electrochemical gas sensor

Abstract

The application discloses a novel electrochemical gas sensor in the field of gas sensors, which comprises a shell and a cover body, the shell is internally sequentially provided with an induction electrode, an electrolyte and a counting electrode from top to bottom, the upper and lower surfaces of the induction electrode and the counting electrode are both provided with a water permeation prevention film, the bottom of the shell is provided with two detection pins, the induction electrode and the counting electrode are both electrically connected with the corresponding detection pins through wires, and a gas diffusion film is arranged on the water permeation prevention film on the upper surface of the induction electrode; an arc-shaped bimetallic strip is fixedly connected in the shell above the gas diffusion film, the surface of the bimetallic strip is provided with a heating sheet, a plurality of second air holes are formed in the cover body, the top wall in the shell is of an arc-shaped structure matched with the shape of the bimetallic strip in a deformation state, and the bimetallic strip blocks the second air holes in the deformation state. The application has the advantages of fast response speed, difficulty in being interfered by external air during detection, good internal gas flowability and the ability of realizing flexible response and accurate detection.

Description

Technical Field

[0001] This invention belongs to the field of gas sensors, specifically an electrochemical gas sensor. Background Technology

[0002] Electrochemical gas sensors are a commonly used gas detection technology that can be used to monitor and measure gas concentrations in the environment. They utilize the current generated between the gas and the electrode by an electrochemical reaction to quantitatively or qualitatively detect the presence and concentration of a target gas.

[0003] In the prior art, electrochemical diffusion gas sensors are widely used due to their simple structure and low cost. For example, the electrochemical diffusion gas sensor described in Chinese patent document CN2886564Y has the following structure: a convex upper cap with a circular hole (1), an O-ring (2), an upper housing with a convex retaining ring at the bottom (3), a spiral cap with a central circular hole (4), a lower housing with a groove at the top (5), an electrical socket (6), a cover (7), an electrode lead channel (8), a circular gas hole in the cap (9), a circular gas hole in the spiral cap (10), a working electrode (11), a counter electrode (12), a reference electrode (13), a moisture-absorbing material (14), and a circular hole in the cover (15).

[0004] The electrochemical diffusion gas sensor described above uses gas diffusion to detect gas concentration, but it has the following problems: (1) The response time usually takes several seconds to several minutes, which is not suitable for application scenarios that require a fast response; (2) Since the gas flow is maintained continuously during the detection process, the external gas can easily interfere with the sensor detection, affecting the accuracy of the detection results; (3) The gas flow inside the sensor is poor, and the gas molecules stay in the sensor for a long time, which may lead to saturation or unevenness of the reaction, thereby reducing the accuracy of the measurement.

[0005] In summary, there is an urgent need to develop a novel electrochemical gas sensor that features fast response speed, is less susceptible to external air interference during detection, and has good internal gas flow. Summary of the Invention

[0006] The purpose of this invention is to provide an electrochemical gas sensor that solves the problems of slow response, susceptibility to external air interference during detection, and reduced accuracy due to poor fluidity in electrochemical diffusion gas sensors.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows: An electrochemical gas sensor includes a housing and a cover, the cover being detachably connected to the top of the housing. A sensing electrode, an electrolyte, and a counting electrode are arranged sequentially from top to bottom inside the housing. Water-proof membranes are provided on the upper and lower surfaces of the sensing electrode and the counting electrode. Two detection pins are provided at the bottom of the housing. The sensing electrode and the counting electrode are electrically connected to the corresponding detection pins through wires. A gas diffusion membrane is provided on the water-proof membrane on the upper surface of the sensing electrode.

[0008] An arc-shaped bimetallic strip is fixedly connected inside the shell above the gas diffusion membrane. Several first vent holes are opened on the bimetallic strip. In the initial state, the bimetallic strip is concave into the shell. In the deformed state, the bimetallic strip protrudes outward from the shell. A heating element is provided on the surface of the bimetallic strip. Several second vent holes are opened on the cover. The inner top wall of the shell is an arc-shaped structure that matches the shape of the bimetallic strip in the deformed state. In the deformed state, the bimetallic strip blocks the second vent holes.

[0009] The technical principles of the above solution are as follows:

[0010] Under normal conditions, outside air slowly enters the housing through the second and first vents. Before gas concentration detection, the bimetallic strip is heated by a heating element. During the heating process, the temperature around the bimetallic strip inside the housing rises. According to the laws of thermodynamics, gas in the low-temperature space tends to flow to the high-temperature space, thus guiding the outside air to the area above the gas diffusion membrane inside the housing. After being heated to the deformation temperature of the bimetallic strip, the bimetallic strip deforms and blocks the second vent, preventing outside air from entering the housing. The air that has already entered the housing passes through the gas diffusion membrane and comes into contact with the sensing electrode, and then passes through the electrolyte and the counting electrode in sequence. By detecting the number of electrons passing between the two detection pins, the gas concentration can be detected quickly and accurately.

[0011] The above approach has the following beneficial effects:

[0012] 1. This solution promotes the flow of external gas into the gas sensor by heating the bimetallic strip to increase the temperature. After the bimetallic strip is heated to the deformation temperature, it deforms and blocks the continuous flow of external gas into the sensor. The gas concentration is then detected in a relatively independent space. Compared with existing electrochemical diffusion gas sensors, this solution reduces the interference of external gas and enables the sensor to respond to changes in the target gas more quickly.

[0013] 2. This solution detects the concentration of the target gas after blocking the continuous entry of external gas. Compared with existing electrochemical diffusion gas sensors, it can reduce the exchange rate between the sensor and the external environment gas, improve the detection sensitivity and response speed, and reduce the interference of external gas on the sensor detection, making it more accurate in detecting the target gas.

[0014] 3. Compared with gas sensors that use fans or pumps to guide outside air in, this solution has a simpler structure, occupies less space, and has a lower cost.

[0015] 4. This solution uses a heating element to keep the bimetallic strip heated, preventing outside air from flowing into the sensor for an extended period. This enables zero-concentration detection because the target gas continuously decreases after reacting within the sensor. In the absence of the target gas, the sensor's output current should be close to zero, thus enabling basic calibration of the sensor. Compared to traditional sensor calibration methods, this solution eliminates the need to disassemble the sensor and can be achieved through remote control.

[0016] Furthermore, both the first and second vents are rectangular structures. A blocking strip matching the shape of the first vent is provided on the upper surface of the bimetallic strip. When the bimetallic strip is deformed, its upper surface is attached to the top wall of the cover body, and the positions of the first and second vents are staggered, with the blocking strip extending into the second vent.

[0017] Beneficial effects: After the bimetallic strip deforms, the blocking strip extends into the second vent, which on the one hand promotes a more sealed blockage of the second vent, and on the other hand, it can push out the dust in the air attached to the second vent instantly when it extends into the second vent.

[0018] Furthermore, a temperature sensor is provided on the housing or cover. The temperature sensor is used to collect the ambient temperature. The temperature sensor signal is connected to a controller. The controller is connected to the heating element. The controller is used to adjust the heating temperature of the heating element according to the ambient temperature collected by the temperature sensor.

[0019] Beneficial effects: By detecting the external temperature of the gas sensor through a temperature sensor, the heating temperature of the bimetallic sensor is adjusted, reducing unnecessary energy consumption and ensuring that the heating temperature is reached, while guiding outside air into the sensor.

[0020] Furthermore, the heating element is a mesh heating wire, which is fixedly connected to the bottom of the bimetallic strip.

[0021] Beneficial effects: The mesh heating wire enables uniform heating of the bimetallic strip while allowing sufficient space for the inflow of outside air.

[0022] Furthermore, the diffusion membrane includes an overlapping gas diffusion regulating plate and a gas diffusion layer, the gas diffusion layer being bonded to a waterproof membrane on the upper surface of the sensing electrode.

[0023] Beneficial effects: The gas diffusion regulating plate and gas diffusion layer can control the amount of air in contact with the sensing electrode per unit time.

[0024] Furthermore, a reference electrode is disposed inside the housing between the sensing electrode and the counting electrode, and a reference pin is disposed at the bottom of the housing. The reference electrode is electrically connected to the reference pin through a wire.

[0025] Beneficial effects: It provides a stable potential reference through the reference electrode and maintains the sensitivity and accuracy of the sensor.

[0026] Furthermore, a filter sheet is provided on the upper surface of the cover, which is composed of activated carbon and hydrophilic polymer.

[0027] Beneficial effect: The filter removes impurities from the air entering the sensor.

[0028] Furthermore, the bimetallic strip is an iron-nickel alloy bimetallic strip, with a deformation temperature of 50°C and a reset temperature of 20°C.

[0029] Beneficial effects: The use of an iron-nickel alloy bimetallic strip with a deformation temperature of 50℃ and a reset temperature of 20℃ can adapt to gas monitoring in more environments.

[0030] Furthermore, it also includes a counter, which includes a base and a display. The base has a mounting slot, and the mounting slot has connection holes that correspond one-to-one with the detection pins and reference pins. A conductive sheet is placed in the connection hole, and the conductive sheet is connected to the controller signal. The controller is connected to the display signal.

[0031] Beneficial effects: By displaying the gas concentration detected by the sensor installed in its mounting slot through a counter, the concentration of the target gas can be obtained more conveniently and intuitively.

[0032] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the undeformed bimetallic strip structure of an embodiment of the electrochemical gas sensor of the present invention;

[0034] Figure 2 This is a schematic diagram of the deformed bimetallic strip structure of an embodiment of the electrochemical gas sensor of the present invention;

[0035] Figure 3 This is a top view schematic diagram of an embodiment of the electrochemical gas sensor of the present invention;

[0036] Figure 4 This is a schematic diagram of the counter structure of an embodiment of the electrochemical gas sensor of the present invention. Detailed Implementation

[0037] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0038] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "vertical", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0039] In the description of this invention, unless otherwise specified and limited, it should be noted that the terms "installation", "connection" and "linking" should be interpreted broadly. For example, they can refer to mechanical or electrical connections, or internal connections between two components. They can be direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0040] The following detailed description illustrates the specific implementation method:

[0041] The reference numerals in the accompanying drawings include: filter 1, second vent 2, cover 3, temperature sensor 4, bimetallic strip 5, heating element 6, wire 7, detection pin 8, reference pin 9, waterproof membrane 10, counting electrode 11, reference electrode 12, sensing electrode 13, gas diffusion layer 14, gas diffusion adjustment plate 15, first vent 16, blocking strip 17, display 18, fixing plate 19, mounting groove 20, and connection hole 21.

[0042] Example 1

[0043] As attached Figure 1-3 As shown: An electrochemical gas sensor includes a housing and a cover 3. The cover 3 is detachably connected to the top of the housing by a threaded connection. The shapes of the housing and the cover 3 can be selected according to requirements. In this embodiment, the housing and the cover 3 are cylindrical in shape after being connected, and the top of the cover 3 is arc-shaped, while the bottom of the housing is flat.

[0044] The housing contains, from top to bottom, a sensing electrode 13, an electrolyte, and a counting electrode 11. Both the sensing electrode 13 and the counting electrode 11 are made of metal, alloy, or conductive polymer and are fixedly connected to the inner wall of the housing. Waterproof membranes 10 are provided on the upper and lower surfaces of the sensing electrode 13 and the counting electrode 11 and are also fixedly connected to the inner wall of the housing. Two detection pins 8 are fixedly connected to the bottom of the housing and extend to the outside of the bottom of the housing. The sensing electrode 13 and the counting electrode 11 are electrically connected to the corresponding detection pins 8 through wires 7.

[0045] The number of electrons flowing between the sensing electrode 13 and the counting electrode 11 can be measured by connecting a measuring device (ammeter) between the two detection pins 8. The concentration of the target gas can be determined by the number of electrons detected.

[0046] A gas diffusion membrane is provided on the waterproof membrane 10 on the upper surface of the sensing electrode 13. The diffusion membrane includes an overlapping gas diffusion regulating plate 15 and a gas diffusion layer 14. The gas diffusion layer 14 is attached to the waterproof membrane 10 on the upper surface of the sensing electrode 13. The overlapping gas diffusion regulating plate 15 and the gas diffusion layer 14 can effectively limit the amount of target gas passing through per unit time, so that an appropriate amount of gas comes into contact with the sensing electrode 13 in sequence, ensuring the stability of the detection results.

[0047] An arc-shaped bimetallic strip 5 is fixedly connected inside the shell above the gas diffusion membrane. Several first vent holes 16 are opened on the bimetallic strip 5. In the initial state, the bimetallic strip 5 is concave into the shell. In the deformed state, the bimetallic strip 5 protrudes outward from the shell. In this embodiment, the bimetallic strip 5 is an iron-nickel alloy bimetallic strip 5. The deformation temperature of the iron-nickel alloy bimetallic strip 5 is 50°C, and the reset temperature of the iron-nickel alloy bimetallic strip 5 is 20°C. That is, when the temperature of the bimetallic strip 5 reaches 50°C, it deforms and protrudes outward from the shell. When the temperature of the metal strip drops to 20°C, it resets and concaves inward from the shell.

[0048] Of course, the bimetallic strip 5 can be selected according to the application scenario of the gas sensor. For gas sensors used in high-temperature environments, a bimetallic strip 5 with a higher deformation temperature and reset temperature can be selected, while for gas sensors used in low-temperature environments, a bimetallic strip 5 with a lower deformation temperature and reset temperature can be selected.

[0049] A heating element 6 is welded and fixed to the surface of the bimetallic sheet 5. The heating element 6 can heat the bimetallic sheet 5 regardless of where it is fixed on the surface of the bimetallic sheet. However, in order to enhance the effect of guiding outside air in, this embodiment uses a mesh heating wire as the heating element 6. The mesh heating wire is fixedly connected to the bottom of the bimetallic sheet 5, so as to guide outside air to the internal area of ​​the shell below the bimetallic sheet 5.

[0050] The upper surface of the cover 3 is provided with a filter sheet 1, which is composed of activated carbon and hydrophilic polymer; the cover 3 is provided with several second vent holes 2, and the inner top wall of the shell is an arc-shaped structure that matches the shape of the bimetallic strip 5 in the deformed state, and the bimetallic strip 5 blocks the second vent holes 2 in the deformed state.

[0051] Both the first vent 16 and the second vent 2 are rectangular structures. The upper surface of the bimetallic sheet 5 is integrally formed with a blocking strip 17 that matches the shape of the first vent 16. When the bimetallic sheet 5 is deformed, its upper surface is attached to the inner top wall of the cover 3, and the positions of the first vent 16 and the second vent 2 are staggered. When the bimetallic sheet 5 is deformed, the blocking strip 17 extends into the first vent 16.

[0052] A temperature sensor 4 is fixedly connected to the housing or cover 3. In this embodiment, the temperature sensor 4 is fixedly connected to the outer wall of the housing by screws. The temperature sensor 4 is used to collect the ambient temperature. The temperature sensor 4 is connected to a controller. The controller is connected to the heating element 6. The controller is used to adjust the heating temperature of the heating element 6 according to the ambient temperature collected by the temperature sensor 4. The controller controls the heating temperature of the heating element 6 according to the changes in the ambient air, so that the bimetallic strip 5 can be fully deformed.

[0053] A reference electrode 12 is disposed inside the housing between the sensing electrode 13 and the counting electrode 11. A reference pin 9 is fixedly connected to the bottom of the housing. The reference electrode 12 is electrically connected to the reference pin 9 through a wire 7. The reference electrode 12 provides a stable potential reference and maintains the sensitivity and accuracy of the sensor.

[0054] The specific implementation process is as follows:

[0055] For example, for Concentration is detected. After the controller acquires the ambient temperature from the temperature sensor 4, it controls the heating element 6 to heat the bottom of the bimetallic strip 5 at an appropriate temperature. During the heating process, the temperature of the space between the bimetallic strip 5 and the gas diffusion regulating plate 15 continuously rises. According to the laws of thermodynamics, gas in the low-temperature space tends to flow to the high-temperature space, thus... The gas gradually flows into the space between the bimetallic strip 5 and the gas diffusion regulating plate 15; when heated to 50°C, the bimetallic strip 5 deforms and blocks the second vent 2 with the blocking strip 17. The gas cannot continuously flow into the gas sensor through the first vent 16 and the second vent 2, and the gas is located in the space between the bimetallic strip 5 and the gas diffusion regulating plate 15. Gas diffusion regulating plate 15 and gas diffusion layer 14 pass through sequentially, combined with attached Figure 1 and 2 The direction of the arrow shown is Flow direction.

[0056] Contact with water vapor in the air ( ) ) react to produce Simultaneously, hydrogen ions are released ( ) and electrons ( The reaction formula is as follows:

[0057]

[0058] Hydrogen ions generated by sensing electrode 13 ( ) and electrons ( The hydrogen ions () reach the counting electrode 11 via the electrolyte and the measuring device (ammeter) connected to the detection pin 8, respectively; the hydrogen ions reaching the counting electrode ( ) and electrons ( ) reacts with oxygen in the air on the counting electrode 11. ) react to produce water ( The reaction formula is as follows:

[0059]

[0060] The number of electrons collected by the measuring device (galvanometer) is used to measure... Concentration detection.

[0061] The solution in this embodiment has a fast response speed, is not easily affected by external air interference during detection, and has good internal gas flow, enabling accurate detection of the target gas concentration.

[0062] Example 2

[0063] As attached Figure 4 As shown, the difference from Embodiment 1 is that a counter is also included. The counter is mainly for the convenience of users to directly read the gas sensor detection results. The counter includes a base and a display 18. Three sets of fixing plates 19 are fixedly connected to the side of the base. The fixing plates 19 can fix the counter. A mounting groove 20 is provided on the base. A connection hole 21 corresponding to the detection pin 8 and the reference pin 9 is provided in the mounting groove 20. A conductive sheet is provided in the connection hole 21. The conductive sheet is connected to the controller signal. The controller is connected to the display 18 signal. In this embodiment, the controller completes the temperature control of the heating element 6 and detects the number of electrons flowing between the two detection pins 8.

[0064] After inserting the three pins into the connection hole 21, the detection pin 8 and the reference pin 9 are electrically connected to the controller. After the target gas concentration is detected by following the steps in Example 1, the specific value of the target gas concentration is displayed on the display 18.

[0065] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific structures and / or characteristics in the solutions are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. An electrochemical gas sensor, characterized in that: It includes a housing and a cover. The cover is detachably connected to the top of the housing. Inside the housing, from top to bottom, there are a sensing electrode, an electrolyte, and a counting electrode. The upper and lower surfaces of the sensing electrode and the counting electrode are covered with a water-proof membrane. There are two detection pins at the bottom of the housing. The sensing electrode and the counting electrode are electrically connected to the corresponding detection pins through wires. A gas diffusion membrane is provided on the water-proof membrane on the upper surface of the sensing electrode. An arc-shaped bimetallic strip is fixedly connected inside the shell above the gas diffusion membrane. Several first vent holes are opened on the bimetallic strip. In the initial state, the bimetallic strip is concave into the shell. In the deformed state, the bimetallic strip protrudes out of the shell. A heating element is provided on the surface of the bimetallic strip. Several second vent holes are opened on the cover. The inner top wall of the shell is an arc-shaped structure that matches the shape of the bimetallic strip in the deformed state. The bimetallic strip blocks the second vent holes in the deformed state. Both the first vent and the second vent are rectangular structures. A blocking strip matching the shape of the first vent is provided on the upper surface of the bimetallic strip. When the bimetallic strip is deformed, its upper surface is attached to the top wall of the cover. The positions of the first vent and the second vent are staggered, and the blocking strip extends into the first vent. The heating element is a mesh heating wire, which is fixedly connected to the bottom of the bimetallic strip.

2. The electrochemical gas sensor according to claim 1, characterized in that: A temperature sensor is installed on the housing or cover. The temperature sensor is used to collect the ambient temperature. The temperature sensor signal is connected to a controller. The controller is connected to the heating element signal. The controller is used to adjust the heating temperature of the heating element according to the ambient temperature collected by the temperature sensor.

3. The electrochemical gas sensor according to claim 2, characterized in that: The diffusion membrane includes an overlapping gas diffusion regulating plate and a gas diffusion layer, which is bonded to a waterproof membrane on the upper surface of the sensing electrode.

4. The electrochemical gas sensor according to claim 3, characterized in that: A reference electrode is disposed inside the housing between the sensing electrode and the counting electrode, and a reference pin is disposed at the bottom of the housing. The reference electrode is electrically connected to the reference pin through a wire.

5. The electrochemical gas sensor according to claim 4, characterized in that: The upper surface of the cover is equipped with a filter sheet, which is composed of activated carbon and hydrophilic polymer.

6. The electrochemical gas sensor according to claim 5, characterized in that: The bimetallic strip is an iron-nickel alloy bimetallic strip. The deformation temperature of the iron-nickel alloy bimetallic strip is 50℃, and the reset temperature of the iron-nickel alloy bimetallic strip is 20℃.

7. The electrochemical gas sensor according to claim 6, characterized in that: It also includes a counter, which includes a base and a display. The base has a mounting slot, and the mounting slot has connection holes that correspond one-to-one with the detection pins and reference pins. A conductive sheet is placed in the connection hole, and the conductive sheet is connected to the controller signal. The controller is connected to the display signal.

Images