A gas relative measurement sensor

Abstract

The application discloses a kind of gas relative measurement sensors, including shell, chamber placed in shell, resistance wire placed in chamber, column for resistance wire winding, for the sealing of chamber below end, for the chamber entrance of gas to be detected into chamber and gas sensor outlet, sensor further includes filter structure and aperture adjustment structure, filter structure is placed between chamber entrance and chamber, aperture adjustment structure is placed at chamber entrance, and for adjusting the size of chamber entrance;The application can avoid the security risk caused by the change of gas content, solve the problem of poor measurement accuracy caused by the excessive flow rate of the measured gas and the uneven contact with the resistance wire during the measurement process;Improve detection efficiency, so that the sensor better adapts to the working environment;Improve the accuracy, stability and precision of sensor measurement;At the same time, to avoid the damage of resistance wire.

Description

Technical Field

[0001] This invention relates to the field of gas measurement sensor technology, and in particular to a gas relative measurement sensor. Background Technology

[0002] Gas relative emission measurement sensors: The detected gas and a specified gas pass through a working chamber and a compensation chamber respectively. The difference in heat carried away by the resistance wire is used to determine the relative percentage content of a certain component in the detected gas relative to the specified gas. Gas relative emission measurement sensors can monitor the gas composition in industrial pipelines in real time, effectively avoiding safety hazards caused by changes in the concentration of a certain component. They are widely used in civil, industrial, and environmental monitoring fields, such as measuring the methane content in natural gas and the relative content of uranium hexafluoride in depleted nuclear fuel, providing detection equipment for safe production.

[0003] Thermal conductivity gas relative composition measurement sensors are devices that measure the concentration of a certain component in a gas based on the difference in thermal conductivity of different gases. They have advantages such as a large detection range, good operational stability, long service life, and high stability and reliability. However, they also have problems such as excessive gas flow rate and uneven contact with the resistance wire. In addition, many automated production lines need to monitor the gas in the pipeline at all times. Traditional gas analyzers or sensors are often unable to adapt to the harsh working conditions in production. In measurement environments with many impurities and high pressure, the measurement results are affected, and even the sensor is damaged, which cannot guarantee the measurement accuracy and service life.

[0004] For example, existing technology such as application number CN201420109397.3 describes a miniature thermal conductivity gas sensor for binary gas detection. This sensor includes a substrate and a miniature heater, a component sensor, a flow sensor, and a temperature sensor respectively disposed on the substrate. The miniature heater, component sensor, and flow sensor are all cantilever structures. The two ends of the miniature heater, component sensor, and flow sensor are fixed to the substrate, with the middle suspended. This design suffers from problems such as excessively high gas flow rate, resulting in uneven contact with the resistance wire. Furthermore, the introduction of high-pressure gas with many impurities can easily damage the sensor.

[0005] In view of the above-mentioned shortcomings of existing thermal conductivity gas relative composition measurement sensors, the present invention provides a gas relative measurement sensor to solve the above-mentioned technical problems. Summary of the Invention

[0006] The purpose of this invention is to provide a gas relative measurement sensor that solves the problems of excessive gas flow rate and uneven contact with the resistance wire during detection; and that traditional gas analyzers or sensors are often unable to adapt to the harsh working conditions in production, affecting the measurement results or even damaging the sensor in measurement environments with many impurities and high pressure, thus failing to guarantee measurement accuracy and service life.

[0007] The present invention is implemented as follows: a gas relative measurement sensor includes a housing, a chamber placed inside the housing, a resistance wire placed inside the chamber, a column for winding the resistance wire, a sealing head for sealing the bottom of the chamber, a chamber inlet for the gas to be detected to enter the chamber, and a gas sensor outlet. The sensor also includes a filter structure and an aperture adjustment structure. The filter structure is placed between the chamber inlet and the chamber, and the aperture adjustment structure is placed at the chamber inlet and is used to adjust the size of the chamber inlet.

[0008] A further technical solution of the present invention is: the aperture adjustment structure includes a damping plate, an orifice baffle and a drive motor, the damping plate is provided with a through hole, the orifice baffle is connected to the output end of the drive motor, and the orifice baffle can be rotated to adjust the size of the through hole.

[0009] A further technical solution of the present invention is: the output end of the drive motor is rotatably connected to the center of the damping plate and the orifice baffle is connected to the outer periphery of the output end; the orifice baffle is placed at the back of the damping plate and fits against the damping plate; the drive motor is used to drive the orifice baffle to rotate thereby adjusting the size of the through hole.

[0010] A further technical solution of the present invention is: the orifice baffle is fan-shaped, the orifice baffle is placed between the through holes, and the orifice baffle can be rotated to adjust the size of the through holes.

[0011] A further technical solution of the present invention is that the damping plate is circular, and the outer diameter of the damping plate is in transition fit with the inner diameter of the chamber inlet.

[0012] An aperture adjustment structure is set up to regulate pipeline pressure and control gas flow, so that the measured gas and the thermistor of the sensor can fully exchange heat, achieving a uniform and stable flow velocity of the incoming gas entering the working chamber. This makes signal acquisition more accurate and stable, reduces the impact of sudden changes in acquisition frequency and flow rate on the output signal, and improves the accuracy and precision of sensor measurements.

[0013] A further technical solution of the present invention is that when the inlet equivalent aperture is 0.3-0.5mm and the outlet equivalent aperture is 1.5-2mm, it has a better output signal.

[0014] A further technical solution of the present invention is: the filter structure includes a membrane tube and a nickel mesh, the nickel mesh being rolled on the membrane tube, and the filter structure being connected to the base plate of the sensor.

[0015] A further technical solution of the present invention is that an adsorbent is provided between the nickel meshes.

[0016] The filtration structure significantly reduces the probability of solid particles and soluble gel particles entering the sensor's core components from 68% to below 3%, resolving the issue of impurities in the production environment affecting the sensor's measurement accuracy and sensitivity. Furthermore, this structure reduces incoming flow impact, facilitating the acquisition of stable test signals and extending the sensor's lifespan.

[0017] A further technical solution of the present invention is: the sensor further includes a tension adjustment structure, the tension adjustment structure is placed in the cavity, and the tension adjustment structure is used to adjust the tension of the resistance wire according to the gas flow rate.

[0018] A further technical solution of the present invention is: the tension adjustment structure includes an upper clamp, a lower clamp, and a spring placed between the upper clamp and the lower clamp, the resistance wire of the sensor is placed between the upper clamp and the lower clamp, the upper clamp is provided with a guide hole, the upper clamp is fixed in the cavity, and there is a gap between the lower clamp and the cavity.

[0019] A further technical solution of the present invention is that the lower clamp can move up and down under the influence of the gas flow velocity.

[0020] When gas flows into the sensor, the airflow passes through the gap between the lower clamp and the chamber and exchanges heat with the resistance wire. When the gas flow rate changes, the lower clamp, under the combined action of gravity, the pushing force of the airflow, and the spring force, adapts to the flow rate of the gas being measured, changing its position to adjust the tension of the resistance wire, thereby changing the resistance wire's resistance value. This allows the sensor to adapt to test gases with different flow rates. When the gas flow rate increases, the airflow pushes the lower clamp upward, compressing the spring, reducing the resistance wire tension and thus the resistance value. When the gas flow rate decreases, the spring pushes the lower clamp downward, stretching the spring, increasing the resistance wire tension and thus the resistance value. This ensures that the airflow velocity along the resistance wire during gas exchange within the working chamber is not too high and remains uniform, controlling the airflow and resistance wire to achieve sufficient and stable heat exchange. Simultaneously, the resistance value of the resistance wire changes with the airflow magnitude, making the output electrical signal more stable. The adjustment structure achieves adaptive adjustment of gas flow rate and resistance wire resistance value, reducing the impact of sudden changes in signal acquisition frequency and flow rate on the output signal, and improving the accuracy, stability, and precision of the sensor measurement.

[0021] The sensor's measuring element consists of a working chamber and a compensation chamber, between which are installed working resistance wires R1 and R2 and an adjustment structure. The resistance wires are made of nickel-chromium alloy and manufactured through specific heat treatment and aging processes. The working chamber is connected to the analyte, which is primarily a mixture of heavy gas and air. The compensation chamber is connected to the atmosphere and contains resistors R3 and R4 for compensation. When air (nitrogen) is present in the analyte, the thermal conductivity of the gas mixture changes, causing a change in the resistance values ​​of R1 and R2. As a result, the sensor's bridge circuit becomes unbalanced, and an output voltage whose value is directly proportional to the air (nitrogen) content appears.

[0022] The beneficial effects of this invention are as follows: This invention can accurately measure the relative percentage content of a certain component in the detected gas relative to that component in a specified gas, thereby enabling real-time detection of gas component content in industrial pipelines and effectively avoiding safety hazards caused by changes in gas content; the orifice adjustment structure can effectively reduce the flow rate, control the airflow and ensure sufficient heat exchange between the resistance wire, and solve the problem of poor measurement accuracy caused by excessive gas flow rate and uneven contact with the resistance wire during the measurement process; the filter structure solves the problem of measurement results being affected by a large number of impurities, which cannot guarantee the longevity of the sensor, improves detection efficiency, and makes the sensor better adaptable to the working environment;

[0023] The adjustable structure ensures that the airflow velocity along the resistance wire is not too high and is uniform during gas exchange in the working chamber, controlling the airflow and resistance wire to achieve sufficient and stable heat exchange. At the same time, the resistance value of the resistance wire changes with the airflow magnitude, making the output electrical signal more stable. The adjustable structure realizes adaptive adjustment of gas flow rate and resistance wire resistance value, reducing the impact of sudden changes in signal acquisition frequency and flow rate on the output signal, and improving the accuracy, stability and precision of sensor measurement. At the same time, it also prevents damage to the resistance wire. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of a gas relative measurement sensor provided by the present invention;

[0025] Figure 2 This is the AA cross-sectional view provided by the present invention;

[0026] Figure 3 This is a BB cross-sectional view provided by the present invention;

[0027] Figure 4 This is a circuit diagram of the sensor detection circuit provided by the present invention;

[0028] Figure 5 This is a schematic diagram of the adjustment structure provided by the present invention;

[0029] Figure 6 This is a schematic diagram of the aperture adjustment structure provided by the present invention.

[0030] Reference numerals: 1: End cap; 2: Housing; 4: Resistance wire; 5: Column; 6: Filter structure; 7: Flange; 8: Circuit module; 9: Cover; 10: Zero-point calibrator; 11: Plug; 12: Compensation chamber; 13: Working chamber; 14: Sensor gas outlet; 15: Compensation chamber inlet; 16: Working chamber inlet; 17: Orifice adjustment structure; 171: Damping plate; 172: Orifice baffle; 173: Drive motor; 174: Through hole; 18: Tension adjustment structure; 181: Upper clamp; 182: Lower clamp; 183: Spring. Detailed Implementation

[0031] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0032] It should be noted that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding and reading. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0033] Example 1:

[0034] Figure 1-6 A gas relative measurement sensor is shown, including a housing 2, a chamber placed inside the housing 2, a resistance wire 4 placed inside the chamber, a column 5 for winding the resistance wire, a sealing head 1 for sealing the bottom of the chamber, a chamber inlet for the gas to be detected to enter the chamber, and a gas sensor outlet 14. The sensor also includes a filter structure 6 and an aperture adjustment structure 17. The filter structure 6 is placed between the chamber inlet and the chamber, and the aperture adjustment structure 17 is placed at the chamber inlet and is used to adjust the size of the chamber inlet.

[0035] In this embodiment, the sensor comprises a measuring element and a circuit. The measuring element consists of a gas sensor housing 2, two parallel cylindrical working chambers 13 and a compensation chamber 12 within the housing 2, a resistance wire 4 serving as the sensing element, a column 5 wound around the resistance wire 4, a sealing head 1 at the bottom of the chambers to ensure airtightness, a flange 7 for fixing the sensor's mounting position, a working chamber inlet 16 leading to the working chamber 13, a compensation chamber inlet 15 leading to the compensation chamber 12, and a gas sensor outlet 14. The circuit includes a circuit module 8, which is covered by a cover 9 connected to the housing 2. A zero-point calibrator 10 is located inside the cover 9, and a plug 11 is mounted on the cover 9. The sensor also includes a filter structure 6 to protect the sensing element from interference from other impurities and an aperture adjustment structure 17. The aperture adjustment structure 17 is located at the chamber inlet and is used to adjust the size of the chamber inlet. The chambers include the working chamber 13 and the compensation chamber 12.

[0036] In this embodiment, the aperture adjustment structure 17 includes a damping plate 171, an orifice baffle 172, and a drive motor 173. The damping plate 171 is provided with a through hole 174. The orifice baffle 172 is connected to the output end of the drive motor 173. The orifice baffle 172 can be rotated to adjust the size of the through hole 174.

[0037] In this embodiment, the output end of the drive motor 173 is rotatably connected to the center of the damping plate 171, and the orifice baffle 172 is connected to the outer periphery of the output end. The orifice baffle 172 is placed at the back of the damping plate 171 and fits against the damping plate 171. The drive motor 173 is used to drive the orifice baffle 172 to rotate, thereby adjusting the size of the through hole 174.

[0038] In this embodiment, the orifice baffle 172 is fan-shaped and is placed between the through holes 174. The orifice baffle 172 can be rotated to adjust the size of the through holes 174.

[0039] In this embodiment, the damping plate 171 is circular, and the outer diameter of the damping plate 171 transitions to the inner diameter of the chamber inlet.

[0040] In a preferred embodiment, the measuring element is equipped with an orifice adjustment structure that allows for controllable orifice adjustment at the working chamber inlet, the compensation chamber inlet, and the gas sensor outlet. The orifice adjustment structure consists of a circular damping plate, an orifice baffle, and a micro servo motor. The outer diameter of the circular damping plate is in transition fit with the inner diameter of the inlet and outlet pipes, and it is positioned at the sensor chamber inlet and the gas sensor outlet 14.

[0041] In a preferred embodiment, four identical through holes are evenly distributed on the circular damping plate; the orifice baffle consists of four identical fan-shaped blades in the shape of a windmill at the center of the circular damping plate, which are in close contact with the circular damping plate and can change the area of ​​the through holes by rotating to block them.

[0042] In a preferred embodiment, a miniature servo motor is provided at the center of the orifice baffle. The fan-shaped blades can be rotated by the miniature servo motor, thereby changing the size of the area blocked by the through-hole orifice and achieving precise adjustment of the equivalent aperture. The equivalent aperture adjustment range can reach 0-5mm. When the inlet equivalent aperture is 0.3-0.5mm and the outlet equivalent aperture is 1.5-2mm, it has a better output signal.

[0043] In this embodiment, the filter structure 6 includes a membrane tube and a nickel mesh, with the nickel mesh rolled on the membrane tube, and the filter structure is connected to the base plate of the sensor.

[0044] In this embodiment, an adsorbent is provided between the nickel meshes.

[0045] In this embodiment, the filtration structure of the measuring element adopts a multi-layered dense mesh structure, mainly consisting of a membrane tube and a nickel mesh. The membrane tube is 0.7 mm thick and 12 mm in diameter, and is made by nickel powder spraying onto a mold. The nickel mesh is made of a special nickel-chromium alloy, which has excellent corrosion resistance. The nickel mesh is rolled onto the membrane tube, and the multiple layers of nickel mesh are welded together with the membrane tube to the base plate. Even if a single layer of the filter is damaged, the sensor can still function normally. Circular granular adsorbents are added between each layer to adsorb impurities, thus forming a special type of filtration system that effectively blocks large solid particles and soluble gel particles, enabling efficient and long-lasting impurity filtration.

[0046] In this embodiment, the sensor further includes a tension adjustment structure 18, which is placed in the chamber and is used to adjust the tension of the resistance wire according to the gas flow rate.

[0047] In this embodiment, the tension adjustment structure 18 includes an upper clamp 181, a lower clamp 182, and a spring 183 placed between the upper clamp 181 and the lower clamp 182. The resistance wire of the sensor is placed between the upper clamp 181 and the lower clamp 182. The upper clamp 181 is provided with a guide hole and is fixed in the cavity. There is a gap between the lower clamp 182 and the cavity.

[0048] In this embodiment, the lower chuck 182 can move up and down depending on the magnitude of the gas flow velocity.

[0049] In this embodiment, the adjustment structure consists of upper and lower circular flat clamps that fix the resistance wire, and a spring between the upper and lower clamps. The upper clamp is fixed and has a guide hole, through which gas can flow out; the lower clamp can move up and down with the extension and retraction of the spring, and has a certain gap with the outer wall of the working chamber and the outer wall of the compensation chamber, with a gap size of 0.1-2mm.

[0050] During sensor use, the valve connecting the gas sensor outlet to the equipment must be closed before checking the gas sensor's "zero point". After the valve has been closed for 30 minutes, check the output voltage value and, if necessary, calibrate the "zero point".

[0051] If the sensor test environment pressure is less than 133Pa, the power supply voltage should be cut off to prevent the sensitive element from overheating in a vacuum, which could cause changes in the sensitivity of the gas sensor or melt the resistance wire of the sensitive element.

[0052] The gas sensor has an output resistance of 120±5Ω. When the load resistance is 300±30Ω and the output is within 100mV, the gas sensor sensitivity is 14mV / V·%. Within the range of 0-10V·%, the sensor's basic permissible conversion error must not exceed ±20% of the upper limit of measurement.

[0053] In summary, the gas relative measurement sensor of the present invention can accurately measure the relative percentage content of a certain component of the detected gas relative to that component in a specified gas, thereby enabling real-time detection of gas component content in industrial pipelines.

[0054] The sensor's measuring element consists of a working chamber and a compensation chamber, with working resistance wires R1 and R2 and an adjustment mechanism between them. The resistance wires are made of nickel-chromium alloy and manufactured through specific heat treatment and aging processes. The working chamber is connected to the analyzed medium, primarily a mixture of heavy gas and air, while the compensation chamber is connected to the atmosphere and contains resistors R3 and R4 for compensation. When air (nitrogen) is present in the analyzed medium, it causes a change in the thermal conductivity of the gas mixture, resulting in a change in the resistance values ​​of R1 and R2. This causes the sensor's bridge circuit to become unbalanced, resulting in an output voltage whose value is directly proportional to the air (nitrogen) content. The circuit diagram of the sensor's detection circuit is shown below. Figure 4 As shown.

[0055] To further illustrate the stability of the output signal of the gas relative measurement sensor provided by this invention, and the necessity of setting up the adjustment structure, the equivalent inlet and outlet apertures of different groups are adjusted by the adjustment structure for comparison and explanation, as follows:

[0056] The effects of different inlet and outlet orifice plate diameters on the output electrical signal are shown in Table 1.

[0057] Table 1. Influence of different inlet and outlet orifice diameters on output electrical signal

[0058]

[0059] As shown in Table 1, when the inlet equivalent aperture is 0.3-0.5 mm and the outlet equivalent aperture is 1.5-2 mm, the sensor can output an electrical signal with a certain duration, stable value, and easy detection, enabling accurate and stable measurement of the relative content of the gas being measured. When the inlet equivalent aperture is 0.4 mm and the outlet equivalent aperture is 1.7 mm, the sensor achieves the best measurement effect, and the output signal has a significant hump shape. When the inlet and outlet equivalent apertures are smaller than the optimized range, the output signal is short and stable, which is not conducive to signal detection. When they are larger than the optimized range, the output signal strength is weak and unstable, which is also not conducive to signal detection.

[0060] Comparative Example 1:

[0061] This embodiment includes components other than the adjustment structure in Embodiment 1. The electrical signal output is compared with that in Embodiment 1 to detect flow rate fluctuations, and the results regarding the electrical signal output when the adjustment structure is used are shown in Table 2.

[0062] Table 2 shows the electrical signal output when a resistance wire elastic adjustment system is used.

[0063]

[0064] As shown in Table 2, when there are fluctuations in flow velocity, without the resistance wire elastic adjustment system, the output voltage signal fluctuates with the flow velocity, making stable signal measurement impossible and affecting the stability and accuracy of the measurement. When the resistance wire elastic adjustment system is used, the sensor can adaptively adjust to the flow, and the output electrical signal tends to stabilize after a short period of small fluctuations, significantly improving the stability, reliability and accuracy of the measurement.

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A gas relative measurement sensor, comprising a housing (2), a chamber disposed within the housing (2), a resistance wire (4) disposed within the chamber, a column (5) for winding the resistance wire, a sealing head (1) for sealing the bottom of the chamber, a chamber inlet for the gas to be detected to enter the chamber, and a gas sensor outlet (14), characterized in that: The sensor also includes a filter structure (6) and an aperture adjustment structure (17). The filter structure (6) is placed between the chamber inlet and the chamber, and the aperture adjustment structure (17) is placed at the chamber inlet and the gas sensor outlet (14) and is used to adjust the size of the chamber inlet and the gas sensor outlet (14). The sensor also includes a tension adjustment structure (18), which is placed in the chamber and is used to adjust the tension of the resistance wire according to the gas flow rate. The tension adjustment structure (18) includes an upper clamp (181), a lower clamp (182), and a spring (183) placed between the upper clamp (181) and the lower clamp (182). The resistance wire of the sensor is placed between the upper clamp (181) and the lower clamp (182). The upper clamp (181) is provided with a flow guide hole and is fixed in the chamber. There is a gap between the lower clamp (182) and the chamber. The lower clamp (182) can move up and down under the influence of the gas flow rate.

2. A gas relative measurement sensor according to claim 1, characterized in that, The aperture adjustment structure (17) includes a damping plate (171), an orifice baffle (172), and a drive motor (173). The damping plate (171) has a through hole (174). The orifice baffle (172) is connected to the output end of the drive motor (173). The orifice baffle (172) can be rotated to adjust the size of the through hole (174).

3. A gas relative measurement sensor according to claim 2, characterized in that, The output end of the drive motor (173) is rotatably connected to the center of the damping plate (171), and the orifice baffle (172) is connected to the outer periphery of the output end. The orifice baffle (172) is placed at the back of the damping plate (171) and is in contact with the damping plate (171). The drive motor (173) is used to drive the orifice baffle (172) to rotate, thereby adjusting the size of the through hole (174).

4. A gas relative measurement sensor according to claim 2, characterized in that, The orifice baffle (172) is fan-shaped and is placed between the through holes (174). The orifice baffle (172) can be rotated to adjust the size of the through holes (174).

5. A gas relative measurement sensor according to claim 2, characterized in that, The damping plate (171) is circular, and the outer diameter of the damping plate (171) transitions to the inner diameter of the chamber inlet and the gas sensor outlet (14).

6. A gas relative measurement sensor according to any one of claims 1-5, characterized in that, The filter structure (6) includes a membrane tube and a nickel mesh, with the nickel mesh rolled on the membrane tube, and the filter structure is connected to the base plate of the sensor.

7. A gas relative measurement sensor according to claim 6, characterized in that, An adsorbent is provided between the nickel meshes.

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