Hydrogen concentration sensor

Abstract

The invention discloses a hydrogen concentration sensor which comprises a thermoelectric power generation module, a concentration detection module and a control module, wherein the temperature difference power generation module carries out catalytic combustion when hydrogen is sucked in so as to generate target voltage, and the target voltage is used for supplying power to the concentration detection module and the control module; the concentration detection module is used for detecting the hydrogen concentration in the environment after power supply, generating a voltage signal and sending the voltage signal to the control module; and the control module is used for judging the hydrogen concentration in the environment according to the voltage signal. Therefore, compared with a linear hydrogen concentration sensor, the self-powered hydrogen concentration sensor has the advantages that an additional power supply is not needed, complicated circuits and related circuit loss are avoided, the sensor can be integrated and miniaturized, the sensor can be better applied to a complicated environment, and the self-powered hydrogen concentration sensor can guarantee continuous monitoring.

Description

Technical Field

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

[0002] Hydrogen energy has the advantages of high efficiency and cleanliness, and will replace traditional energy in the future. However, since hydrogen is flammable and explosive, it has extremely strict requirements in preparation, storage, transportation and use, and temperature, pressure and hydrogen concentration sensors are needed to monitor its internal and external environment.

[0003] At present, electrochemical oxygen sensors are commonly used in sensors for monitoring hydrogen. When encountering oxygen, a chemical reaction occurs, and the change in electrical signals caused by the chemical reaction is used as the detection object, thereby achieving effective detection of oxygen. Since the potential generated by the electrochemical oxygen sensor is independent of the size of the sensor, the electrochemical oxygen sensor has the characteristics of miniaturization and high sensitivity.

[0004] However, the coverage area of ​​this sensor is limited, and when the communication harness is too long, the communication is affected. In addition, the sensor harness is inconvenient to route and requires power supply. If the harness housing is broken, it is easy to cause explosion and other hazards. Summary of the invention

[0005] In view of the above problems, the present invention is proposed to provide a hydrogen concentration sensor, which ensures continuous monitoring of hydrogen concentration by self-powering and does not require complicated line connections.

[0006] According to a first aspect of the present invention, there is provided a hydrogen concentration sensor, comprising: a temperature difference power generation module, a concentration detection module and a control module;

[0007] The temperature difference power generation module performs catalytic combustion when inhaling hydrogen to generate a target voltage for supplying power to the concentration detection module and the control module; the concentration detection module is used to detect the hydrogen concentration in the environment after power is supplied, generate a voltage signal, and send it to the control module; the control module is used to determine the hydrogen concentration in the environment based on the voltage signal.

[0008] Optionally, the temperature difference power generation module includes a hot-end semiconductor and a cold-end semiconductor; a catalyst for catalytic combustion of hydrogen is attached to the hot-end semiconductor.

[0009] Optionally, the control module also includes a boost module; the boost module is used to boost the target voltage when the target voltage generated by the temperature difference power generation module is less than a voltage threshold, to obtain a boosted voltage, and to supply the boosted voltage to the concentration detection module.

[0010] Optionally, the operating mode of the control module includes a deep sleep mode and a wake-up mode;

[0011] The control module is activated and enters the wake-up mode when receiving the target voltage of the temperature difference power generation module, and is activated and enters the wake-up mode when receiving the voltage signal sent by the concentration detection module.

[0012] Optionally, the control module is also used to generate a leakage signal when the hydrogen concentration is less than or equal to 1%, and use the temperature difference to charge the energy storage device in the control module; when the hydrogen concentration is greater than 1% and less than 2%, an alarm signal is issued.

[0013] Optionally, the hydrogen concentration sensor further includes an output module connected to the control module;

[0014] The output module includes an audible and visual alarm submodule and an external voltage output submodule.

[0015] Optionally, the external voltage output submodule includes a power amplifier circuit, and the power amplifier circuit is used to control an external valve and control a switching pipeline.

[0016] Optionally, the concentration detection module is a catalytic combustion type hydrogen sensitive element.

[0017] The embodiments of this specification have at least the following technical effects:

[0018] A hydrogen concentration sensor provided in an embodiment of the present specification includes a thermoelectric power generation module, a concentration detection module and a control module; wherein the thermoelectric power generation module performs catalytic combustion when inhaling hydrogen to generate a target voltage for supplying power to the concentration detection module and the control module; the concentration detection module is used to detect the hydrogen concentration in the environment after power is supplied, generate a voltage signal, and send it to the control module; the control module is used to determine the hydrogen concentration in the environment based on the voltage signal. In this way, compared with the wired hydrogen concentration sensor, no additional power supply is required, no complicated lines and related line losses are required, the sensor can be integrated and miniaturized, so that it can be better used in complex environments, and the self-powered hydrogen concentration sensor can ensure continuous monitoring.

[0019] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Also, throughout the accompanying drawings, the same reference figures are used to represent the same components. In the drawings:

[0021] Figure 1 A schematic diagram of a hydrogen concentration sensor in an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0025] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0026] At present, electrochemical oxygen sensors are commonly used in sensors for monitoring hydrogen. When encountering oxygen, a chemical reaction occurs, and the change in electrical signals caused by the chemical reaction is used as the detection object, thereby achieving effective detection of oxygen. Since the potential generated by the electrochemical oxygen sensor is independent of the size of the sensor, the electrochemical oxygen sensor has the characteristics of miniaturization and high sensitivity.

[0027] However, the coverage area of ​​this sensor is limited, and when the communication harness is too long, the communication is affected. In addition, the sensor harness is inconvenient to route and requires power supply. If the harness housing is broken, it is easy to cause explosion and other hazards.

[0028] Based on the above situation, an embodiment of the present invention provides a hydrogen concentration sensor, which ensures continuous monitoring of hydrogen concentration by self-powering, and does not require complicated line connections. The hydrogen concentration sensor of this embodiment is a catalytic combustion sensor, which has the advantages of simple structure, accurate response, good stability, quantitative detection, long life, etc., and is widely used in the detection of flammable and explosive gases.

[0029] The detection principle of the catalytic combustion sensor is to use sensitive elements, compensation elements and fixed resistors to form a Wheatstone bridge. The gas undergoes catalytic combustion on the surface of the catalyst. The increase in combustion temperature causes the resistance value of the sensing resistor to change, breaking the balance of the bridge, thereby outputting a stable voltage signal that is proportional to the gas concentration.

[0030] Combination Figure 1 As shown, the hydrogen concentration sensor of this embodiment includes: a temperature difference power generation module, a concentration detection module and a control module;

[0031] Among them, the temperature difference power generation module performs catalytic combustion when inhaling hydrogen to generate a target voltage for supplying power to the concentration detection module and the control module; the concentration detection module is used to detect the hydrogen concentration in the environment after receiving power, generate a voltage signal, and send it to the control module; the control module is used to determine the hydrogen concentration in the environment based on the voltage signal.

[0032] Specifically, the hydrogen concentration sensor is arranged in the target environment. For example, multiple hydrogen concentration sensors are arranged on the roof and / or wall of the hydrogen filling station. The thermoelectric power generation module includes a hot-end semiconductor and a cold-end semiconductor; a catalyst for catalytic combustion of hydrogen is attached to the hot-end semiconductor. When hydrogen leaks in the target environment, the thermoelectric power generation module in the hydrogen concentration sensor performs catalytic combustion through the inhaled hydrogen, so that the temperature difference between the hot-end semiconductor and the cold-end semiconductor in the thermoelectric power generation module becomes larger, thereby generating a target voltage according to the Seebeck effect, thereby powering the control module and the concentration detection module. The concentration detection module can be a catalytic combustion type hydrogen sensitive element.

[0033] The concentration detection module can use a hydrogen-sensitive detection unit (catalytic combustion type, semiconductor type, electrochemical type prepared by MEMS process). Taking the catalytic combustion type hydrogen-sensitive element prepared by MEMS process as an example, a Wheatstone bridge is formed by using a hydrogen-sensitive element, a compensation element and a fixed resistor. Hydrogen undergoes catalytic combustion on the surface of the catalyst. The increase in combustion temperature causes the resistance value of the inductive resistor of the Wheatstone bridge to change, breaking the balance of the bridge, thereby outputting a stable voltage signal proportional to the hydrogen concentration, and giving the voltage signal to the control module. The control module determines the hydrogen concentration in the target environment based on the voltage signal related to the hydrogen concentration.

[0034] Among them, the thermoelectric power generation module is mainly based on the Seebeck effect of semiconductors, that is, thermoelectric conversion, which mainly uses the Seebeck effect of semiconductor materials to effectively convert thermal energy into electrical energy. The Seebeck effect, also known as the first thermoelectric effect, refers to the thermoelectric phenomenon of the voltage difference between two substances caused by the temperature difference between two different electrical conductors or semiconductors. The direction of the thermoelectric potential is generally stipulated as follows: electrons flow from negative to positive at the hot end. In a loop composed of two metals A and B, if the temperatures of the two contact points are different, a current will appear in the loop, which is called a thermocurrent. The corresponding electromotive force is called a thermoelectric potential, and its direction depends on the direction of the temperature gradient. The cause of the Seebeck effect can be simply explained as the carriers in the conductor moving from the hot end to the cold end under the temperature gradient and accumulating at the cold end, thereby forming a potential difference inside the material, and at the same time generating a reverse charge flow under the action of the potential difference. When the charge flow of the thermal motion reaches a dynamic equilibrium with the internal electric field, a stable thermoelectric potential is formed at both ends of the semiconductor. The thermoelectric potential of semiconductors is large and can be used as a thermoelectric generator. Relying on the Seebeck effect, catalytic combustion side circuit, thermoelectric conversion is mainly based on semiconductor temperature difference power generation of the Seebeck effect. Temperature difference power generation can directly convert the heat energy in the environment into DC power. As long as there is a temperature difference between the hot and cold ends, the thermoelectric collector will generate DC power. Usually, the thermoelectric collector can obtain several hundred milliwatts of energy and can replace battery power in some specific fields. Thermoelectric collection module converts the heat energy in the environment into electrical energy.

[0035] In the thermoelectric power generation module, in a closed loop composed of two different types of semiconductor materials, when the temperatures of the two contacts are different, the potential generated in the loop converts thermal energy into electrical energy. The hot-end semiconductor is attached with a catalyst for hydrogen catalytic combustion by synthesis or coating. Among them, the selection of catalysts for catalytic combustion: Pt and Pd are selected for precious metal loading; tin dioxide, titanium dioxide, aluminum oxide, silicon dioxide are selected for carriers; rare earth modified Y; the preparation process can be MEMS or vapor deposition, electromagnetic sputtering, etc.; the reaction structure can be designed as a microchannel or turbine burner. The catalyst selectivity of the thermoelectric power generation module may be relatively poor, but the catalyst of the concentration detection module requires strong anti-interference. For the thermoelectric power generation module, when there is no hydrogen leakage but there is a certain temperature difference, power generation can be supplemented.

[0036] The collection method is suction type. In order to reduce costs and power consumption, the pumping type is not used. When the leaked hydrogen diffuses and is inhaled into the hydrogen concentration sensor, a catalytic combustion reaction occurs in the hot-end semiconductor. Depending on the catalyst material and preparation process, the catalytic combustion temperature is about 500-600°C. The cold-end semiconductor is at room temperature (the cold end is wrapped by insulation material), and the temperature difference between the cold and hot ends is large, so the target voltage (about tens to one hundred millivolts) can be generated based on the Seebeck effect.

[0037] Regarding the concentration detection module, the catalytic combustion sensor prepared by MEMS technology is widely used in the detection of flammable and explosive gases due to its simple structure, accurate response, good stability, quantitative detection, and long life. The detection principle of the catalytic combustion sensor is to use sensitive elements, compensation elements and fixed resistors to form a Wheatstone bridge. The gas undergoes catalytic combustion on the surface of the catalyst of the detection module. The increase in combustion temperature causes the resistance value of the inductive resistor to change, breaking the balance of the bridge, thereby outputting a stable voltage signal proportional to the gas concentration.

[0038] The control module can use ultra-low power chips, and can select chips with ultra-low sleep current and ultra-low wake-up time. For example, the Wuhan Core Original CW32L083 chip can be used, which has ultra-low deep sleep current and ultra-low wake-up time, that is, the standby current can be as low as 0.62ua, and the wake-up time can be as low as 4us. It should be noted that the chip models in the above examples are only for illustration, and this embodiment is not limited to this. Other ultra-low power chips that meet the requirements of this embodiment also fall within the protection scope of this embodiment.

[0039] In this embodiment, the working modes of the control module include a deep sleep mode and a wake-up mode; the control module is activated and enters the wake-up mode when receiving the target voltage of the temperature difference power generation module, and is activated and enters the wake-up mode when receiving the voltage signal sent by the concentration detection module.

[0040] In actual use, the control module is in deep sleep mode for a long time; the wake-up working mode can be activated by hydrogen catalytic combustion power generation or concentration detection module, as well as periodic automatic wake-up; the control module periodically (the period can be adjusted as needed) wakes up from deep sleep mode and collects the voltage signal of the concentration detection module once, and sends it to the next level. If the voltage signal is normal, the control module immediately switches to deep sleep mode.

[0041] It should be noted that the control module will calculate the calorific value of hydrogen catalytic combustion based on the power generation, thereby inferring the amount of hydrogen leakage, which can be used for auxiliary verification with the hydrogen leakage calculated by the temperature difference power generation module and the hydrogen leakage detected by the concentration detection module.

[0042] In addition, in one embodiment, the control module also includes a boost module; the boost module is used to increase the target voltage when the target voltage generated by the temperature difference power generation module is less than a voltage threshold, to obtain a boosted voltage, and to supply the boosted voltage to the concentration detection module.

[0043] In this embodiment, the open circuit voltage of the temperature difference power generation module is too low, and a boost circuit is required for rectification and amplification. Specifically, energy storage can be performed through energy storage elements; energy storage elements can be selected from lithium batteries or capacitors. The simplest design can eliminate energy storage elements and directly supply power for hydrogen concentration detection and communication alarm after rectification and boost circuits; the control module processes, calculates and analyzes, converts the voltage signal transmitted back by the concentration detection module, and determines the fault level according to the specific situation of hydrogen leakage (i.e., hydrogen concentration) and performs corresponding operations.

[0044] This embodiment divides the fault level of hydrogen leakage into three levels, and the specific processing strategy is: when the hydrogen concentration is lower than 0.5%, only the temperature difference is used to generate electricity to charge the energy storage device in the control module; when the hydrogen concentration is greater than 0.5% and less than or equal to 1%, a leakage signal is generated, and the temperature difference is used to charge the energy storage device in the control module, and charging is not triggered at this time; when the hydrogen concentration is greater than 1% and less than 2%, the control module sends an alarm signal and triggers an audible and visual alarm. It should be noted that the threshold ratio mentioned above can be set according to the actual requirements of the customer, and this embodiment does not limit this.

[0045] In addition, in one embodiment, the hydrogen concentration sensor further includes an output module connected to the control module; the output module includes an audible and visual alarm submodule and an external voltage output submodule.

[0046] The external voltage output submodule includes a power amplifier circuit, which is used to control an external valve and control a switching pipeline.

[0047] The sound and light alarm submodule can select buzzers, speakers, LED lights, etc. as warning signals; the external voltage output submodule can be connected to valves, etc. in the absence of power, to achieve functions such as independent control of valves, switching pipelines, and starting discharge.

[0048] When the hydrogen concentration is greater than 2%, the external voltage output submodule controls the external valve and the corresponding operation of the control switching pipeline;

[0049] In summary, taking the current 35MPa gaseous hydrogen storage system as an example, when hydrogen is added, the entire vehicle is turned off, the hydrogen controller (HCU) stops supplying power, and the wired hydrogen concentration sensor stops detecting. The self-powered hydrogen concentration sensor of this embodiment without power dependence can ensure continuous monitoring and can perform operations such as alarms. Compared with the wired hydrogen concentration sensor, the hydrogen concentration sensor of this embodiment does not require an additional power supply, does not have complicated lines and related line losses, and can integrate and miniaturize the sensor to make it better used in complex environments, and the self-powered hydrogen concentration sensor can ensure continuous monitoring. It can be used in the hydrogen emission process to ensure that the hydrogen has completely escaped.

[0050] In addition, the detection effect of the hydrogen concentration sensor of this embodiment is still not affected in a low temperature environment, or even better. Self-powered power is based on temperature difference power generation, and the low temperature environment will slightly reduce the activity of the catalyst, but the greater the temperature difference, the greater the power generation. It can even be considered that the controller first heats the resistor to provide initial heat (small resistor, only heating the local position of the catalyst) for catalytic combustion, and the post-combustion heat can be completely used to supplement power generation.

[0051] For industrial sites, polluted areas, and areas where it is inconvenient to expose wire harnesses, they can be fixed to the top of the space with positioning bolts, eliminating the need for wire harnesses and power supply. When hydrogen leaks, the hydrogen concentration sensor can detect the hydrogen concentration and also issue an audible and visual alarm.

[0052] The hydrogen concentration sensor in this embodiment can be distributed in multiple points in the target environment to form a hydrogen leakage detection network for monitoring hydrogen leakage, which can quickly determine the hydrogen leakage situation, issue an audible and visual alarm for leakage, and analyze and calculate the concentration distribution in the distributed network to quickly determine the leakage area, provide emergency disposal reference, or connect to the emergency management system to stimulate the execution of corresponding operations; or can interact with the control system at the same time according to the auxiliary connection. When a leak occurs and the power is off, the valve can be controlled by the self-powered system.

[0053] The above are only various embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A hydrogen concentration sensor, characterized in that: include: Temperature difference power generation module, concentration detection module and control module; The temperature difference power generation module performs catalytic combustion when inhaling hydrogen to generate a target voltage for supplying power to the concentration detection module and the control module; the concentration detection module is used to detect the hydrogen concentration in the environment after power is supplied, generate a voltage signal, and send it to the control module; the control module is used to determine the hydrogen concentration in the environment based on the voltage signal.

2. The hydrogen concentration sensor according to claim 1, characterized in that: The temperature difference power generation module comprises a hot end semiconductor and a cold end semiconductor; a catalyst for catalytic combustion of hydrogen is attached to the hot end semiconductor.

3. The hydrogen concentration sensor according to claim 1, characterized in that: The control module also includes a boost module; the boost module is used to boost the target voltage when the target voltage generated by the temperature difference power generation module is less than a voltage threshold, to obtain a boosted voltage, and to supply the boosted voltage to the concentration detection module.

4. The hydrogen concentration sensor according to claim 1, characterized in that: The working modes of the control module include a deep sleep mode and a wake-up mode; The control module is activated and enters the wake-up mode when receiving the target voltage of the temperature difference power generation module, and is activated and enters the wake-up mode when receiving the voltage signal sent by the concentration detection module.

5. The hydrogen concentration sensor according to claim 1, characterized in that: The control module is also used to generate a leakage signal when the hydrogen concentration is less than or equal to 1%, and use the temperature difference to charge the energy storage device in the control module; when the hydrogen concentration is greater than 1% and less than 2%, an alarm signal is issued.

6. The hydrogen concentration sensor according to claim 1, characterized in that: The hydrogen concentration sensor also includes an output module connected to the control module; The output module includes an audible and visual alarm submodule and an external voltage output submodule.

7. The hydrogen concentration sensor according to claim 6, characterized in that: The external voltage output submodule includes a power amplifier circuit, and the power amplifier circuit is used to control the external valve and control the switching pipeline.

8. The hydrogen concentration sensor according to claim 1, characterized in that: The concentration detection module is a catalytic combustion type hydrogen sensitive element.

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