Hydrogen sensor

Abstract

The hydrogen sensor comprises a detection shell, a temperature sensitive element and a control element, the internal space of the detection shell serves as a detection inner cavity, and the detection inner cavity communicates with a gas inlet pipe and a gas outlet pipe; a Wheatstone bridge circuit is arranged in the temperature sensitive element, and corresponding electric signals can be output according to different hydrogen concentrations; the control element is arranged in the detection inner cavity, databases in one-to-one correspondence between hydrogen concentration and electric signals are arranged in the control element, and the control element is connected with the temperature sensitive element and used for receiving the electric signals output by the temperature sensitive element and finding out the corresponding hydrogen concentration of the electric signals in the databases. The detection precision and efficiency are higher, and the problem that the measurement precision is poor due to large power consumption and large heat dissipating capacity caused by the fact that a single working resistor is adopted to process electric signals only depending on a complex rear-end circuit is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen detection, in particular to a hydrogen sensor. Background Art

[0002] Hydrogen energy, as an efficient, widely available, and environmentally friendly renewable energy source, is gaining increasing attention worldwide. As an efficient and clean secondary energy source, hydrogen shows great potential in areas such as hydrogen fuel cell vehicles, energy storage systems, and industrial hydrogen applications. Hydrogen can be converted into electricity, heat, and water through the electrochemical reactions of fuel cells, without emitting carbon dioxide and nitrogen oxides, and without any pollution, thus effectively meeting environmental protection requirements. However, hydrogen has an extremely fast diffusion rate, extremely low ignition energy (0.02mJ), a wide flammability range (4%-75%), and its colorless and odorless nature makes leaks difficult to detect directly, placing stringent safety requirements on real-time gas monitoring technology.

[0003] Currently, mainstream hydrogen sensor types include electrochemical, catalytic combustion, semiconductor, and optical, but all present significant technical bottlenecks. While electrochemical sensors offer high sensitivity and low detection limits (ppm level), their electrolytes are susceptible to volatility and contamination, resulting in a lifespan of only 2-3 years. Their performance also degrades significantly in high-temperature or high-humidity environments. Catalytic combustion sensors rely on precious metal catalysts such as platinum and palladium and must operate at high temperatures (>200°C). Long-term operation can lead to failure due to catalyst poisoning or sintering. Their limited detection range (0%-4%) makes them difficult to meet the demands of wide concentration detection. Semiconductor sensors (such as metal oxides) offer fast response and low cost, but are susceptible to interference from ambient temperature and humidity, leading to significant baseline drift. Optical sensors (such as infrared and laser sensors) offer contactless detection, but they rely on precision optical components, are bulky and costly, and their light source stability and resistance to dust contamination are insufficient, limiting their application in vehicles or industrial settings.

[0004] Among the numerous sensors used to detect hydrogen leaks, MEMS thermal conductivity hydrogen sensors offer broad potential for development due to their fast response, wide detection range, diverse application scenarios, and excellent stability. However, existing MEMS thermal conductivity hydrogen sensors mostly utilize a single working resistor and rely solely on complex back-end circuitry to process the electrical signal. This results in a complex circuit structure and high power consumption. The heat dissipated by the complex circuitry also affects the temperature of the detection chamber, thereby impacting measurement accuracy. Summary of the Invention

[0005] The object of the present invention is to provide a hydrogen sensor that can avoid the influence of complex back-end circuits on measurement accuracy.

[0006] The technical solution of the present invention is:

[0007] A hydrogen sensor comprises: a detection housing, the interior space of which serves as a detection cavity, the detection cavity being connected to an air inlet pipe and an air outlet pipe; four M8 cross-recessed hexagonal head bolts distributed around the detection housing, used to fix the hydrogen sensor to a reactor wall or a wall near a working environment. Compared with other sensors without a fixed structure, the hydrogen sensor has good stability and a wide range of working environments. The temperature-sensitive element has a built-in Wheatstone bridge circuit and can output an electrical signal corresponding to different hydrogen concentrations; a control element disposed in the detection cavity, containing a database with a one-to-one correspondence between hydrogen concentrations and electrical signals. The control element is connected to the temperature-sensitive element and is used to receive the electrical signal output by the temperature-sensitive element and find the hydrogen concentration corresponding to the electrical signal in the database.

[0008] Furthermore, it also includes: a temperature control element, which is arranged in the detection cavity, including: a temperature measuring element, located at the mouth of the air intake pipe, for detecting the temperature of the gas entering the detection cavity from the air intake pipe; a heating element and a cooling element, which are connected and communicated with the temperature measuring element, for adjusting the temperature range of the detection cavity.

[0009] Furthermore, the heating element is a spiral-shaped electric heating element made of nickel-chromium alloy (Ni-Cr). It relies on Joule's law to convert electrical energy into heat energy. The resistivity of nickel-chromium alloy is significantly higher than that of conductor materials such as copper and aluminum. When current passes through, its resistance will hinder the flow of electrons, converting electrical energy into heat energy. The heat generated is Q=I 2 Rt, where I is the current, R is the resistance, and t is the time. The melting point of nickel-chromium alloy is usually above 1400°C, and it can work for a long time at high temperatures without melting. The cooling element is a semiconductor refrigeration sheet made of bismuth telluride (Bi2Te3) material, which performs cooling based on the Peltier effect. When current passes through a loop composed of different conductors (or semiconductors), heat absorption or heat release occurs at the contact surface of the two materials. An electric couple is formed by N-type (electron conductive) and P-type (hole conductive) semiconductor materials. Selenium (Se) is doped into the N-type semiconductor to form a Bi2Te3-Bi2Se3 solid solution, and antimony (Sb) is doped into the P-type semiconductor to form a Bi2Te3-Sb2Te3 solid solution to optimize electrical conductivity and carrier concentration, balance the Seebeck coefficient and thermal conductivity, and improve cooling efficiency. The operating range of bismuth telluride material is -50°C to 150°C, which meets the temperature requirements of the sensor working environment.

[0010] Furthermore, the four resistors in the Wheatstone bridge circuit in the temperature sensitive element are: a fixed resistor R1, a fixed resistor R3, a thermistor R2 and a thermistor R4. The two fixed resistors are made of tin dioxide metal oxide film material, with high resistance accuracy and stable temperature characteristics; the two thermistors are made of metal platinum, which can achieve sensitive response to temperature, and have a high temperature coefficient of resistance (TCR) and good linearity; the four resistors are connected into a closed quadrilateral through the Wheatstone bridge circuit, wherein the fixed resistor R1 and the thermistor R2 are connected in series, and the fixed resistor R3 and the thermistor R4 are connected in series.

[0011] Furthermore, the temperature-sensitive element further includes: an insulating cavity, which is a sealed structure made of silica aerogel material and is filled with an inert gas, such as nitrogen, which has a low thermal conductivity and can prevent ambient temperature changes and impurity gases from affecting the resistance of the fixed resistors. The two fixed resistors are located in the insulating cavity; a measuring cavity, which is made of an alloy material with high thermal conductivity and high strength, such as beryllium bronze (Cu-Be alloy). The measuring cavity has an inlet and an outlet, and both the inlet and outlet are made of palladium silver (Pd-Ag) alloy film, which only allows hydrogen to pass through. The thermistor R2 is located in the measuring cavity; and a reference cavity, which is made of beryllium bronze (Cu-Be alloy) material with high thermal conductivity and can respond to ambient temperature changes to correct and compensate for temperature. The thermistor R4 is sealed in the reference cavity to prevent it from contacting hydrogen. The reference cavity is sealed and insulated from hydrogen, and has high thermal conductivity. When the ambient temperature changes, the temperature of the reference and measurement cavities change synchronously, as do the values of their internal resistors. This ensures that the Wheatstone bridge circuit remains balanced. When hydrogen is present, it enters only the measurement cavity, causing the circuit to output an electrical signal. If the reference cavity is not sealed and insulated from hydrogen, then when the ambient temperature changes and hydrogen is present, the reference cavity is affected by both the ambient temperature and the thermal conductivity of the hydrogen, and the measurement cavity is affected by both. The electrical signal output by the Wheatstone bridge circuit is an erroneous hydrogen concentration signal, because different ambient temperatures at the same hydrogen concentration will produce different output signals. Therefore, the reference cavity is used to compensate for changes in ambient temperature.

[0012] Furthermore, it includes a signal amplifier, and the signal amplifier is connected and communicated with the temperature sensitive element.

[0013] Furthermore, the method for obtaining the database includes the following steps:

[0014] At a constant temperature, hydrogen is introduced into the detection cavity. Due to the high thermal conductivity of hydrogen, the Wheatstone bridge circuit in the temperature sensitive element will lose balance and output an electrical signal corresponding to the hydrogen concentration at that time;

[0015] The output electrical signal is amplified by the signal amplifier and then output to the control element. According to the hydrogen concentration at this time, the linear coefficient between the hydrogen concentration and the electrical signal is obtained;

[0016] Repeat the above steps to sequentially introduce hydrogen of different concentrations into the detection cavity, and construct a database with a one-to-one correspondence between hydrogen concentrations and electrical signals.

[0017] Furthermore, the device further comprises an audible and visual alarm, which is arranged on the top of the detection housing and connected to the control element via a circuit. When the audible and visual alarm receives an electrical signal from the control element, it emits a high-frequency buzzing sound and a flashing strong light to warn the outside world.

[0018] Furthermore, the sensor also includes an aviation plug, located on the top of the detection housing near the audible and visual alarms. This plug is used to connect the detection cavity to the external power source and transmit signals. Compared with conventional electrical plugs, it offers stable contact, better protection, and superior electrical performance, ensuring the normal operation of the sensor circuit.

[0019] Furthermore, existing MEMS thermal conductivity hydrogen sensors are susceptible to corrosion from impurities and harmful gases in the operating environment, leading to degradation of the sensitive material's performance and consequently insufficient long-term stability. For example, poor sealing between sensor components or the use of only a mesh metal structure to intercept hydrogen inlets and outlets can affect detection accuracy and lifespan if the sensor's chip coating or reaction chamber becomes contaminated. The sensors also include an inlet dust shield and an outlet dust shield, each of which is a tubular structure and fits over the inlet and outlet pipes, respectively. The inlet and outlet dust shields are each equipped with a porous, breathable membrane made of polytetrafluoroethylene (PTFE) at their openings. Porous membranes made of polytetrafluoroethylene (PTFE) are not only chemically stable and corrosion-resistant, but also possess superhydrophobic properties, blocking the ingress of liquid water and oil while allowing the free passage of gas (hydrogen). Through process control (such as stretching), porous membranes with varying pore sizes (nano- to micron-scale) can be produced to meet the gas diffusion rate requirements in various operating environments. Furthermore, the porous membrane's ability to block liquid water also ensures that the detection chamber is unaffected by ambient humidity, improving hydrogen detection accuracy and operational stability.

[0020] In addition, the air inlet dust cover and the air outlet dust cover can be removed and replaced, further improving the sensor's anti-pollution ability.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The sensor of the present invention has a detection cavity, and a Wheatstone bridge circuit is arranged in the detection cavity through a temperature sensitive element and connected to a control element. The control element of the present invention can not only receive the electrical signal output by the temperature sensitive element, but also is internally configured with electrical signals output by the temperature sensitive element under a plurality of hydrogen concentrations. When the temperature sensitive element outputs an electrical signal, the control element directly finds the hydrogen concentration corresponding to the electrical signal in the database after receiving the electrical signal. The circuit structure of the present invention is simpler, and the detection accuracy and efficiency are higher. It avoids the use of a single working resistor and reliance on complex back-end circuits to process electrical signals, resulting in high power consumption and heat dissipation, which leads to poor measurement accuracy.

[0023] 2. The temperature-sensitive element of the present invention is configured with multiple chambers. Two non-working resistors (fixed resistors) are placed in a sealed, insulated chamber made of silica aerogel to prevent ambient temperature changes and impurity gases from affecting the resistance of the fixed resistors. One of the working resistors (thermistor R4) is placed in a reference chamber, which is sealed but not insulated and can respond to changes in ambient temperature. The other working resistor (thermistor R2) is located in a measuring chamber. The inlet and outlet of the measuring chamber are made of a palladium-silver (Pd-Ag) alloy film that only allows hydrogen to pass through. This alloy film has a unique selectivity for hydrogen, avoiding the problem of existing MEMS thermal conductivity hydrogen sensors that are non-selective for hydrogen. Any gas with high thermal conductivity (such as helium, methane, and carbon monoxide) entering the sensor will cause the temperature of the working resistor to drop, leading to sensor misidentification and alarm. By placing the non-working resistor and the working resistor in chambers made of different materials, the present invention avoids thermal interference caused by the heat dissipated by the non-working resistor itself and changes in ambient temperature on the working resistor, thereby improving the accuracy of hydrogen concentration detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a cross-sectional view of the sensor of the present invention.

[0025] Figure 2 It is a front view of the sensor of the present invention.

[0026] Figure 3 It is a top view of the sensor of the present invention.

[0027] Figure 4 It is an isometric view of the air outlet dust shield of the present invention.

[0028] Figure 5 Schematic diagram of the internal structure of the temperature sensitive element of the present invention.

[0029] Figure 6 It is a schematic flow chart of the detection control principle of the present invention.

[0030] Among them, 1. Sound and light alarm; 2. Detection shell; 3. Cross groove hexagonal head bolt; 4. Detection inner cavity; 5. Air outlet dust cover; 6. Air outlet pipe; 7. Air inlet dust cover; 8. Air inlet pipe; 9. Temperature measuring element; 10. Refrigeration element; 11. Temperature sensitive element; 12. Heating element; 13. Control element; 14. Signal amplifier; 15. Aviation plug; 16. Wheatstone bridge circuit; 17. Thermal insulation cavity; 18. Measuring cavity; 19. Reference cavity. DETAILED DESCRIPTION

[0031] The following combination Figures 1 to 6 , a detailed description of the specific embodiments of the present invention is provided. In the description of the present invention, it should be understood that the terms "center," "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like, indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings and are intended only to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific direction, be constructed, or operate in a specific direction. Therefore, they should not be construed as limiting the present invention.

[0032] The terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, features specified as "first" or "second" may explicitly or implicitly include one or more of such features; and in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0033] Example

[0034] like Figure 1 As shown, a hydrogen sensor includes: a detection shell 2, a temperature sensitive element 11 and a control element 13, the internal space of the detection shell 2 serves as a detection cavity 4, and the detection cavity 4 is connected to an air inlet pipe 8 and an air outlet pipe 6; Figure 2 As shown, four M8 cross-grooved hexagonal bolts 3 are distributed around the detection housing 2 and are used to fix the hydrogen sensor to the reactor wall or a wall near the working environment. Compared with other sensors without a fixed structure, the hydrogen sensor has good stability and a wide range of working environments; the temperature sensitive element 11 has a built-in Wheatstone bridge circuit 16, which can output corresponding electrical signals according to different hydrogen concentrations; the control element 13 is arranged in the detection cavity 4, and a database with a one-to-one correspondence between hydrogen concentrations and electrical signals is provided inside. The control element 13 is connected to the temperature sensitive element 11 and is used to receive the electrical signal output by the temperature sensitive element 11 and find the hydrogen concentration corresponding to the electrical signal in the database.

[0035] In some embodiments, as Figure 1As shown, a temperature control element is also included. The temperature control element is arranged in the detection cavity 4, including: a temperature measuring element 9, a heating element 12 and a cooling element 10. The temperature measuring element 9 is located at the mouth of the air inlet pipe 8 and is used to detect the temperature of the gas entering the detection cavity 4 from the air inlet pipe 8; the heating element 12 and the cooling element 10 are both connected to the temperature measuring element 9 for communication, and are used to adjust the temperature range of the detection cavity 4.

[0036] In some embodiments, the heating element 12 is a spiral-shaped electric heating element made of nickel-chromium alloy (Ni-Cr). It relies on Joule's law to convert electrical energy into heat energy. The resistivity of nickel-chromium alloy is significantly higher than that of conductive materials such as copper and aluminum. When current passes through, its resistance hinders the flow of electrons, converting electrical energy into heat energy. The heat generated is Q = I 2 Rt, where I is the current, R is the resistance, and t is the time. The melting point of nickel-chromium alloy is typically above 1400°C, and it can operate at high temperatures for long periods without melting. Cooling element 10 is a semiconductor refrigeration plate made of bismuth telluride (Bi2Te3) material, which performs cooling based on the Peltier effect. When current passes through a loop composed of different conductors (or semiconductors), heat absorption or heat release occurs at the contact surface of the two materials. By forming a galvanic pair using N-type (electron conductive) and P-type (hole conductive) semiconductor materials, selenium (Se) is doped into the N-type semiconductor to form a Bi2Te3-Bi2Se3 solid solution, and antimony (Sb) is doped into the P-type semiconductor to form a Bi2Te3-Sb2Te3 solid solution to optimize electrical conductivity and carrier concentration, balance the Seebeck coefficient and thermal conductivity, and improve cooling efficiency. The operating range of bismuth telluride material is -50°C to 150°C, which meets the temperature requirements of the sensor's operating environment.

[0037] In some implementations, such as Figure 5 As shown, the four resistors of the Wheatstone bridge circuit 16 in the temperature sensitive element 11 are: a fixed resistor R1, a fixed resistor R3, a thermistor R2, and a thermistor R4. The two fixed resistors are made of tin dioxide metal oxide film material, with high resistance accuracy and stable temperature characteristics; the two thermistors are made of platinum metal, which can achieve sensitive response to temperature, and have a high temperature coefficient of resistance (TCR) and good linearity. The four resistors are connected into a closed quadrilateral through the Wheatstone bridge circuit 16, wherein the fixed resistor R1 and the thermistor R2 are connected in series, and the fixed resistor R3 and the thermistor R4 are connected in series.

[0038] In some embodiments, the temperature sensitive element 11 further includes: an insulating cavity 17, a measuring cavity 18, and a reference cavity 19. The insulating cavity 17 is a sealed structure made of silica aerogel material and is filled with an inert gas, such as nitrogen, which has a low thermal conductivity and can prevent the ambient temperature changes and impurity gases from affecting the resistance of the fixed resistors. The two fixed resistors are located in the insulating cavity 17; the measuring cavity 18 is made of beryllium bronze (Cu-Be alloy) material. The measuring cavity 18 has an inlet and an outlet, and both the inlet and outlet are made of palladium silver (Pd-Ag) alloy film, which only allows hydrogen to pass through. The thermistor R2 is disposed in the measuring cavity 18; the reference cavity 19 is made of beryllium bronze (Cu-Be alloy) material, which has high thermal conductivity and can respond to ambient temperature changes to correct and compensate for temperature. The thermistor R4 is sealed in the reference cavity 19 to prevent it from contacting hydrogen.

[0039] Reference cavity 19 is sealed and isolates hydrogen, and has high thermal conductivity. When the ambient temperature changes, the temperature of reference cavity 19 and measurement cavity 18 will change synchronously, and the resistance value of their internal resistors will also change synchronously. This ensures that the balance of the Wheatstone bridge circuit is not disrupted. When hydrogen is present, hydrogen only enters measurement cavity 18, and the circuit outputs an electrical signal. If reference cavity 19 is not sealed and isolates hydrogen, then when the ambient temperature changes and hydrogen is present, the reference cavity 19 is affected by both the ambient temperature and the thermal conductivity of hydrogen, and the measurement cavity 18 is affected by both the ambient temperature and the thermal conductivity of hydrogen. In this case, the electrical signal output by the Wheatstone bridge circuit is an erroneous hydrogen concentration signal, because at the same hydrogen concentration, different ambient temperatures will result in different circuit output signals. Therefore, in this embodiment, reference cavity 19 is provided to correct and compensate for ambient temperature changes.

[0040] In some embodiments, a signal amplifier 14 is further included, and the signal amplifier 14 is connected to the temperature sensitive element 11 for communication.

[0041] The working principle of the Wheatstone bridge circuit 16 is as follows:

[0042] VCC represents the power supply voltage of the circuit, GND is the ground terminal of the circuit, and it forms a closed loop with resistors R1, R2, R3, and R4. The output voltage V out =(V out +)-(V out -), the balance condition of the circuit is R1 / R2=R3 / R4, at this time the voltage divider ratio of the two branches of the circuit is equal, there is no voltage output, V out=0; the thermistor R2 is made of metal platinum, and the resistance temperature coefficient of metal platinum is positive, that is, the resistance increases when the temperature rises, and vice versa, the resistance decreases. The relationship between its resistance and temperature is: R(T)=R0[1+α(T-T0)], where T0 is the reference temperature, R0 is the resistance value at the reference temperature, T is the measurement temperature, R(T) is the resistance value at the measurement temperature, and α is the temperature coefficient of platinum resistance, which is approximately 0.00385Ω / ℃; when hydrogen enters the measurement cavity 18, the thermal conductivity of hydrogen is high, which will cause the heat dissipation of the thermistor R2 to accelerate, the temperature T drops, the resistance value of R2 decreases, and the resistance change ΔR=R0·α·ΔT, where ΔT is the change in resistance temperature; at this time, the Wheatstone bridge circuit 16 loses balance, the voltage changes, and the output voltage of the bridge Since R2 decreases, R1, R3, and R4 remain unchanged, so V out <0, the circuit outputs a negative voltage electrical signal, which is amplified by the signal amplifier 14 and then output to the control element 13; the temperature compensation mechanism of the Wheatstone bridge circuit 16 is common mode interference suppression: when the ambient temperature changes and hydrogen enters the detection cavity 4, the resistance change of R2 (affected by hydrogen and ambient temperature) is ΔR H2 +ΔR T , the resistance change of R4 affected by ambient temperature is ΔR T , so the circuit differential output offsets the influence of ambient temperature, the output voltage V out ∝(ΔR H2 +ΔR T )-ΔR T =ΔR H2 , the electrical signal output by the final circuit only reflects the change in the thermistor resistance caused by the change in hydrogen concentration.

[0043] like Figure 6 As shown, the method for obtaining the database includes the following steps:

[0044] At a constant temperature, hydrogen is introduced into the detection cavity 4. Due to the high thermal conductivity of hydrogen, the Wheatstone bridge circuit 16 in the temperature sensitive element 11 will lose balance and output an electrical signal corresponding to the hydrogen concentration at that time.

[0045] The output electrical signal is amplified by the signal amplifier 14 and then output to the control element 13. According to the hydrogen concentration at this time, the linear coefficient between the hydrogen concentration and the electrical signal is obtained;

[0046] Repeat the above steps to sequentially introduce hydrogen of different concentrations into the detection cavity 4 to construct a database with a one-to-one correspondence between hydrogen concentrations and electrical signals.

[0047] like Figure 2 and Figure 3As shown, it also includes an audible and visual alarm 1, which is arranged on the top of the detection housing 2 and is connected to the control element 13 through a circuit. When it receives the electrical signal from the control element 13, it will emit a high-frequency buzzing sound and a flashing strong light to warn the outside world.

[0048] like Figure 1 and Figure 3 As shown, the sensor also includes an aviation plug 15, which is located on the top of the detection housing 2 and near the sound and light alarm 1. It is used to detect the connection between the inner cavity 4 and the external power supply and transmit signals. Compared with ordinary electrical plugs, it has stable contact, good protection performance, and excellent electrical performance, which can ensure the normal operation of the circuit in the sensor.

[0049] In some embodiments, the existing MEMS thermal conductivity hydrogen sensor is susceptible to corrosion by impurities and harmful gases in the working environment, which leads to degradation of the performance of the sensitive material and thus insufficient long-term stability. For example, if the sealing between the sensor components is poor or only a mesh metal structure is used to intercept the hydrogen inlet and outlet, if the chip coating or reaction chamber of the sensor is contaminated, its detection accuracy and life will be affected; Figure 1 、 Figure 2 and Figure 3 As shown, it also includes an air inlet dust cover 7 and an air outlet dust cover 5, and the air inlet dust cover 7 and the air outlet dust cover 5 are both tubular structures, and are respectively sleeved on the air inlet pipe 8 and the air outlet pipe 6, and the pipe mouths of the air inlet dust cover 7 and the air outlet dust cover 5 are provided with a porous medium breathable diaphragm made of polytetrafluoroethylene (PTFE). The porous medium breathable diaphragm made of polytetrafluoroethylene (PTFE) is not only chemically stable, but also has strong corrosion resistance, and has super-hydrophobic properties, can block the entry of liquid water and grease, while allowing the free passage of gas (hydrogen), and it can prepare a porous membrane of different pore sizes (nanometer to micron level) by process control (such as stretching method) to meet the demand of gas diffusion rate under different working environments. Moreover, the characteristic of the porous medium breathable diaphragm blocking liquid water also ensures that the detection chamber is affected by the humidity of the environment, improves its detection accuracy and working stability to hydrogen.

[0050] In addition, the air inlet dust cover 7 and the air outlet dust cover 5 can be disassembled and replaced, which further improves the anti-pollution ability of the sensor.

[0051] The above disclosures are only several preferred specific embodiments of the present invention. However, the embodiments of the present invention are not limited thereto. Any changes that can be conceived by those skilled in the art should fall within the scope of protection of the present invention.

Claims

1. A hydrogen sensor, characterized in that: include: A detection housing (2), the internal space of which serves as a detection inner cavity (4), wherein the detection inner cavity (4) is connected to an air inlet pipe (8) and an air outlet pipe (6); A temperature sensitive element (11) is provided with a Wheatstone bridge circuit and is capable of outputting an electrical signal corresponding to the hydrogen concentration; A control element (13) is arranged in the detection inner cavity (4), and a database is provided therein, in which a one-to-one correspondence between hydrogen concentration and electrical signal is provided. The control element (13) is connected to the temperature sensitive element (11), and is used to receive the electrical signal output by the temperature sensitive element (11) and find the hydrogen concentration corresponding to the electrical signal in the database.

2. A hydrogen sensor according to claim 1, characterized in that: Also includes: A temperature control element is provided in the detection cavity (4), comprising: A temperature measuring element (9) is located at the mouth of the air inlet pipe (8) and is used to detect the temperature of the gas entering the detection cavity (4) from the air inlet pipe (8); The heating element (12) and the cooling element (10) are connected and communicated with the temperature measuring element (9) and are used to adjust the temperature range of the detection inner cavity (4).

3. A hydrogen sensor according to claim 2, characterized in that: The heating element (12) is an electric heating element with a spiral structure made of nickel-chromium alloy; the cooling element (10) is a semiconductor cooling plate made of bismuth telluride material, and performs cooling based on the Peltier effect.

4. A hydrogen sensor according to claim 1, characterized in that: The four resistors of the Wheatstone bridge circuit (16) in the temperature sensitive element (11) are: a fixed resistor R1, a fixed resistor R3, a thermistor R2 and a thermistor R4, the two fixed resistors are made of tin dioxide metal oxide film material; the two thermistors are made of metal platinum and can achieve sensitive response to temperature; the four resistors are connected to form a closed quadrilateral through the Wheatstone bridge circuit (16), wherein the fixed resistor R1 and the thermistor R2 are connected in series, and the fixed resistor R3 and the thermistor R4 are connected in series.

5. A hydrogen sensor according to claim 4, characterized in that: The temperature sensitive element (11) further comprises: The heat-insulating cavity (17) is a sealed structure made of silica aerogel and filled with inert gas. The two fixed resistors are located in the heat-insulating cavity (17); The measuring cavity (18) is made of an alloy material with high thermal conductivity and high strength. The measuring cavity (18) is provided with an inlet and an outlet, and both the inlet and the outlet are made of a palladium-silver alloy film. The thermistor R2 is arranged in the measuring cavity (18); The reference cavity (19) is made of beryllium copper material. The thermistor R4 is sealed in the reference cavity (19) to prevent it from contacting with hydrogen.

6. A hydrogen sensor according to claim 1, characterized in that: It also includes a signal amplifier (14), and the signal amplifier (14) is connected and communicated with the temperature sensitive element (11).

7. The hydrogen sensor according to claim 1, characterized in that: The method for obtaining the database comprises the following steps: At a constant temperature, hydrogen is introduced into the detection inner cavity (4). Due to the high thermal conductivity of hydrogen, the Wheatstone bridge circuit (16) in the temperature sensitive element (11) loses balance and outputs an electrical signal corresponding to the hydrogen concentration state at that time; The output electrical signal is transmitted to the control element (13), and the control element (13) obtains a linear coefficient between the hydrogen concentration and the electrical signal according to the hydrogen concentration at that time; Repeat the above steps to sequentially introduce hydrogen of different concentrations into the detection inner cavity (4) to construct a database with a one-to-one correspondence between hydrogen concentrations and electrical signals.

8. The hydrogen sensor according to claim 1, characterized in that: Also includes: An audible and visual alarm (1) is provided on the top of the detection housing (2) and is connected to a control element (13) via a circuit.

9. The hydrogen sensor according to claim 1, characterized in that: Also includes: An aviation plug (15) is arranged on the top of the detection housing (2) and is used for connecting the detection cavity (4) with an external power supply and transmitting signals.

10. The hydrogen sensor according to claim 1, characterized in that: The utility model also comprises an air inlet dust-blocking cover (7) and an air outlet dust-blocking cover (5), both of which are tube structures and are respectively sleeved on the air inlet pipe (8) and the air outlet pipe (6), and the pipe openings of the air inlet dust-blocking cover (7) and the air outlet dust-blocking cover (5) are both provided with porous medium breathable diaphragms made of polytetrafluoroethylene.

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