Micro air station

Abstract

The application discloses a micro air station, which comprises a temperature control box, an electromagnetic valve module and a plurality of electrochemical sensor assembly structures, wherein each electrochemical sensor assembly structure comprises an electrochemical sensor and a base, the base comprises a Peltier module and a heat conduction module, a recess is formed on the upper surface of the heat conduction module, the Peltier module is arranged in the recess, and the back of the Peltier module is in close contact with the heat conduction module; a shell is connected to the base, and the electrochemical sensor is arranged in the shell; a filter air chamber is arranged inside the shell and below the electrochemical sensor, the filter air chamber is internally hollow to form a cavity, an inlet is arranged on the left side or the right side of the filter air chamber, and the upper surface of the filter air chamber is uniformly provided with protrusions, the end of each protrusion is provided with a capillary hole, the capillary hole is opposite to an electrode of the electrochemical sensor, a gas sample enters the cavity from the inlet and is sprayed from the capillary hole to contact the electrode of the electrochemical sensor. The micro air station has the advantages of simple structure, long service life and accurate measurement.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of air quality monitoring, and particularly relates to a micro air station. BACKGROUND

[0002] Most electrochemical gas sensors are applied in diffusion mode, in which the gas sample from the ambient environment enters the sensor through a small hole in the front face of the sensor (by natural flow of gas molecules). Some devices, however, draw the air / gas sample into the sensor by means of a suction pump. A Teflon membrane is installed at the gas hole to prevent water or oil from entering the sensor. The measurement range and sensitivity of the sensor can be varied by adjusting the size of the gas inlet hole at the design stage. A larger gas inlet hole can increase the sensitivity and resolution of the device, while a smaller gas inlet hole can increase the measurement range, although it reduces the sensitivity and resolution.

[0003] For example, the working principle of an oxygen sensor is similar to that of the electrochemical oxygen sensor described above, but the service life of the oxygen sensor is predictable, so the replacement cycle can also be preset - generally 2-3 years. Unlike toxic gas sensors, oxygen sensors are continuously exposed to the target gas for a long time. In a typical oxygen consumption monitoring application, the oxygen concentration in the sensor operating environment is 20.9%, which will cause a chemical reaction on the lead anode, thereby causing the anode to gradually consume. Therefore, the ability of the sensor to continuously generate current by reacting with oxygen depends on the amount of lead in the electrolyte.

[0004] The service life of an electrochemical sensor for detecting common gases such as carbon monoxide or hydrogen sulfide is usually 2-3 years. However, the service life of a sensor for some special gases, such as hydrogen fluoride gas, is only 12-18 months. The specific use will be extended or shortened accordingly depending on the environment.

[0005] By adding the key mechanism of "temperature compensation", gas detection device manufacturers ensure the performance of the sensor. Gas sensitivity (and zero baseline signal) often changes with temperature, so when the temperature rises and falls, the gas sensitivity changes nonlinearly.

[0006] In the development of gas detection devices, a lot of time is spent on placing the same gas sensor in different temperatures and different concentrations of gas (temperature between -30°C and +50°C). The collected data is processed to generate a temperature compensation algorithm for the gas detector to ensure that the sensor readings remain consistent throughout the operating range.

[0007] In ideal conditions, i.e. temperature and humidity maintained at about 20°C and 60% RH, respectively, and no intrusion of contaminants, some electrochemical sensors are known to operate for more than 11 years, with periodic exposure to target gas environments not limiting the useful life of the sensor. High quality sensors are typically equipped with sufficient catalyst and robust conductors that are not easily consumed by chemical reactions.

[0008] Factors affecting sensor life:

[0009] 1. Extreme temperatures can affect sensor life. At too low a temperature, the sensitivity of the sensor can decrease. A sensor can operate at -40°C, but the sensitivity to the gas can decrease substantially (sensitivity can decrease as much as 80%) and the response time can be significantly longer. Also, at temperatures below -35°C, there is a risk of freezing of the electrolyte.

[0010] 2. Sensor performance can also decrease when the gas concentration is too high. Typically, electrochemical sensors are tested at ten times the design concentration. Sensors with high quality catalysts should be able to withstand such conditions without damage to the chemical properties or long-term performance. Sensors with low quality catalysts can be damaged.

[0011] 3. Humidity is the most significant factor affecting sensors. The ideal operating environment for most electrochemical sensors is 20°C and 60% RH. When the humidity is greater than 60% RH, the electrolyte can be diluted by the absorption of water. In extreme cases, the volume of the electrolyte can increase by a factor of 2 to 3, which can cause the electrolyte to leak from the sensor package through the interface. When the humidity is less than 60% RH, the electrolyte can dehydrate. As the electrolyte dehydrates, the response time of the device can be significantly longer.

[0012] Currently, the assembly structure of electrochemical sensors in the prior art is designed mainly around the factors of water removal and temperature control, which is to extend the useful life of the electrochemical sensor and prevent low (high) temperature from affecting the accuracy of the measurement. However, in the existing assembly structure of electrochemical sensors, when the gas sample contacts the electrochemical sensor, the gas has a large flow rate, the flow direction of the gas sample is generally perpendicular to the direction of the electrodes of the electrochemical sensor, and the gas sample has a large pulsation in the gas flow. The filter screen provided by the electrochemical sensor makes the sensor electrodes not in good contact with the gas sample, which is not conducive to the electrodes to detect the gas sample well. Therefore, the design of the prior art does not consider the real contact of the electrochemical sensor with the ambient gas to be measured, so that the detection accuracy needs to be improved.

[0013] Therefore, there is an urgent need for a micro air station with long service life and high accuracy. SUMMARY

[0014] The application aims to provide a micro air station with long service life and high accuracy.

[0015] To achieve the above-mentioned purpose, the application provides a technical solution, which is a micro air station characterized by comprising:

[0016] a temperature control box, a solenoid valve module and a plurality of electrochemical sensor assembly structures;

[0017] The temperature control box comprises a box body and a box cover, the box cover is sealingly covered on the box body, and the plurality of electrochemical sensor assembly structures are assembled in the temperature control box;

[0018] The solenoid valve module is arranged outside the temperature control box, and the gas sample can be communicated with more than one electrochemical sensor assembly structure through the solenoid valve module;

[0019] The electrochemical sensor assembly structure comprises an electrochemical sensor, a base, a shell and a filter air chamber, the shell is connected to the base, and the electrochemical sensor is arranged in the shell;

[0020] The filter air chamber is arranged inside the shell and below the electrochemical sensor, the filter air chamber is a hollow structure forming a cavity, and the left side or the right side is provided with an inlet, the upper surface of the filter air chamber is uniformly provided with capillary holes, the capillary holes are opposite to the electrodes of the electrochemical sensor, the gas sample enters the cavity from the inlet and is sprayed from the capillary holes to contact the electrodes of the electrochemical sensor.

[0021] The solenoid valve group has one gas inlet and a plurality of gas outlets, and the gas inlet can be controlled to communicate with one of the plurality of gas outlets, and the plurality of gas outlets are respectively communicated with one of the electrochemical sensor assembly structures.

[0022] The upper surface of the filter air chamber is uniformly provided with protrusions, and the end of each protrusion is provided with the capillary hole.

[0023] The base and the shell are connected to each other in a vacuum structure.

[0024] The heat conduction module is an aluminum-based heat dissipation fin.

[0025] Before entering the filter air chamber, the gas sample passes through a water removal device for water removal.

[0026] The filter air chamber is internally provided with a partition, the inlet is arranged at the lower side of the partition, and the upper surface and the lower surface of the partition are uniformly provided with round holes.

[0027] The temperature sensor is arranged between the filter air chamber and the electrochemical sensor, and is used for detecting temperature information of the gas sample sprayed from the capillary hole.

[0028] The humidity sensor is arranged between the filter air chamber and the electrochemical sensor, and is used for detecting humidity information of the gas sample sprayed from the capillary hole.

[0029] The mounting plate is internally arranged in the shell, the electrochemical sensor is mounted on the mounting plate, and the mounting plate is made of heat insulation material.

[0030] Compared with the prior art, in the micro air station, the filter air chamber is arranged inside the shell and below the electrochemical sensor, the filter air chamber is internally hollow to form a cavity, and the left side or the right side is provided with an inlet, the upper surface of the filter air chamber is uniformly provided with protrusions, the end of each protrusion is provided with a capillary hole, the capillary hole is opposite to the electrode of the electrochemical sensor, the gas sample enters the cavity from the inlet and is sprayed from the capillary hole to contact the electrode of the electrochemical sensor. By the filter air chamber, the contact between the electrode of the electrochemical sensor and the gas sample can maximize the simulation of the real environment of the electrochemical sensor for measuring the measured gas, thereby greatly improving the measurement accuracy.

[0031] The present application will become more clear from the following description and the accompanying drawings, which are used to explain the embodiments of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The schematic diagram of one embodiment of the micro air station is shown.

[0033] Figure 2 The schematic diagram of the electromagnetic valve module is shown.

[0034] Figure 3 The cross-sectional view of one embodiment of the electrochemical sensor assembly structure is shown.

[0035] Figure 4 The cross-sectional structure schematic diagram of the filter air chamber is shown.

[0036] Figure 5 The schematic diagram of the upper surface of the filter chamber is shown. DETAILED DESCRIPTION

[0037] Firstly, the target substances that can be monitored by the micro air station generally include: standard pollutants such as ozone (O3), nitrogen dioxide (NO2), nitrogen oxides (NO x ), carbon monoxide (CO), sulfur dioxide (SO2), particulate matter (PM10, PM2.5); other pollutants of particular concern: volatile organic compounds (VOC), hydrogen sulfide (H2S), carbon dioxide (CO2), etc.; and noise, temperature, humidity, wind speed, wind direction, air pressure, etc. In the present application, the micro air station mainly monitors the concentration of target substances accurately through electrochemical sensors.

[0038] Embodiments of the present application will now be described with reference to the accompanying drawings. Reference is made to Figure 1 and 2 As mentioned above, Figure 1 Fig. 1 shows a schematic diagram of an embodiment of a micro air station, Figure 2 Fig. 2 shows a schematic diagram of a solenoid valve module.

[0039] With reference to Figure 1 , the present application discloses a micro air station 200, comprising:

[0040] a temperature control box 10, a solenoid valve module 20 and a plurality of electrochemical sensor assembly structures 100; the material of the temperature control box 10 should be chemically stable and have good overall thermal insulation performance, and the temperature control box 10 should be provided with a temperature control unit for controlling the temperature inside the temperature control box 10. It should be noted that in the non-sampling stage, such as the storage and transportation stage, the temperature control unit can adjust the temperature inside the temperature control box 10 to a temperature range that helps to prolong the service life of the electrochemical sensor; when in the sampling stage, the temperature control unit can adjust the temperature inside the temperature control box 10 to a temperature range that helps to improve the activity of the electrochemical sensor.

[0041] Preferably, the activity of the electrolyte inside the electrochemical sensor is controlled by controlling the temperature of the environment in which the electrochemical sensor is located, i.e. the activity of the electrolyte is purposefully reduced or increased. When the electrochemical sensor is in a non-working state, the temperature of the environment in which the electrochemical sensor is located is reduced (for example, 5°C) to reduce the activity of the electrolyte inside the electrochemical sensor, so that the electrochemical sensor is in a state equivalent to sleep, thereby effectively prolonging the service life of the electrochemical sensor; when the electrochemical sensor is in a working state, the temperature of the environment in which the electrochemical sensor is located is adjusted to a suitable temperature (for example, 25°C) according to the sensitivity of the electrochemical sensor to temperature, to increase the activity of the electrolyte inside the electrochemical sensor and improve the sensitivity of the electrochemical sensor, so that the electrochemical sensor works better and monitors the ambient air quality.

[0042] It should be noted that if the temperature control box 10 is made of a material with good heat insulation performance, and the heat exchange between the inside and outside of the temperature control box 10 can be reduced through structural design, the energy consumption required to control the temperature inside the temperature control box 10 is very low, and the cost of electricity and the cost of replacing new electrochemical sensors (the price is several hundred to thousands per unit) is compared, and the use cost can be expected to be significantly reduced. In addition, the frequency of replacing electrochemical sensors during the use of the device can be reduced, thereby further reducing maintenance costs and labor costs.

[0043] The temperature control box 10 includes a box body 11 and a box cover 12, the box cover 12 is sealingly covered on the box body 11, and a plurality of electrochemical sensor assembly structures 100 are assembled in the temperature control box 10;

[0044] The electromagnetic valve module 20 is arranged outside the temperature control box 10, and the gas sample can be communicated with one or more electrochemical sensor assembly structures 100 through the electromagnetic valve module 20;

[0045] Reference Figure 3 The electrochemical sensor assembly structure 100 includes an electrochemical sensor 1, and further includes:

[0046] The base 2 includes a Peltier module 21 and a heat conduction module 22, the upper surface of the heat conduction module 22 is provided with a recess, and the Peltier module 21 is arranged in the recess, and the back of the Peltier module 21 is in close contact with the heat conduction module 22;

[0047] It should be noted that the Peltier module 21 can work in a cooling state or a heating state by changing the polarity of the electrode loaded thereon, so that one Peltier module can realize cooling or heating, so that the temperature control structure of the device becomes simple and the maintenance is very convenient.

[0048] The back of the Peltier module 21 and the heat conduction module 22 can be coated with a heat-conducting silicone grease to ensure the heat conduction performance of the Peltier module 21 and the heat conduction module 22.

[0049] It should be noted that the bottom of the box body 11 of the temperature control box 10 should be provided with a plurality of slot structures for fixing the heat conduction module 22, the heat conduction module 22 should be fixed from the inside of the box body 11 to the slot, and the main part of the heat conduction module 22 should be exposed outside the box body 11, specifically below the box body 11.

[0050] Exemplarily, the ideal working environment of the electrochemical sensor should be 20℃, considering that the Peltier module 21 has a certain time delay when refrigerating or heating, and thus it is difficult to accurately control the temperature if directly controlling the working time of the Peltier module 21. Therefore, the voltage applied to the Peltier module 21 can be controlled by changing the duty cycle of the pwm square wave, and the temperature of the internal environment of the shell and the gas sample in the filter cartridge can be accurately controlled by the Peltier module 21.

[0051] Reference Figure 3 、 4 and 5, wherein, Figure 4 Fig. 1 shows a schematic diagram of the cross-sectional structure of the filter cartridge, Figure 5 Fig. 2 shows a schematic diagram of the upper surface of the filter cartridge.

[0052] The shell 3 is connected to the base 2, and the electrochemical sensor 1 is arranged in the shell 3. In one embodiment, referring to Figure 3 , the shell 3 is threadedly connected or snap-connected to the base 2, and the connection between the shell 3 and the base 2 is detachable, and the connection needs to achieve airtight connection when connected, to prevent gas leakage and ensure accurate calculation of the flow rate and the concentration of the measured substance in the gas sample.

[0053] Reference Figure 2 , the electromagnetic valve group 20 has one inlet and multiple outlets, and the inlet is controllably communicated with one of the multiple outlets, and the multiple outlets are respectively communicated with one of the electrochemical sensor assembly structures 100.

[0054] It should be noted that in the actual connection process, the multiple outlets are respectively connected to one of the electrochemical sensor assembly structures 100. The electromagnetic valve group 20 can be controllably communicated with any one of the electrochemical sensor assembly structures 100, and the electrochemical sensor in the electrochemical sensor assembly structure 100 communicated is in a working state.

[0055] It should also be noted that "communicated with any one of the electrochemical sensor assembly structures 100" in the above means communicated with the electrochemical sensor in the electrochemical sensor assembly structure 100, so that the electrochemical sensor is in a working state. The electrochemical sensor in the electrochemical sensor assembly structure 100 not in a communicated state is in a non-working state.

[0056] Reference Figure 3 、 4, 5, a filter air chamber 4, which is arranged inside the shell 3 and below the electrochemical sensor 1, is internally hollow to form a cavity 41, and is provided with an inlet 42 (in this embodiment, the inlet is arranged on the left side of the drawing) on the left side or the right side, and the upper surface of the filter air chamber 4 is uniformly provided with protrusions 43, and the end of each protrusion 43 is provided with a capillary hole 44, which is opposite to the electrode of the electrochemical sensor 1, and the gas sample enters the cavity 41 from the inlet 42 and is sprayed from the capillary hole 44 to contact the electrode of the electrochemical sensor 1. Figure 3

[0057] It should be noted that the upper surface of the filter air chamber 4 is uniformly provided with the protrusions 43, and the end of each protrusion 43 is provided with a capillary hole 44, and the capillary hole 44 sprays the gas sample in the filter air chamber 4, which is arranged to better reduce the pulsation of the gas sample and filter the gas sample, and the gas sample from the capillary hole 44 is greatly rectified and filtered, and can be uniformly dispersed, as long as the number of capillary holes 44 is sufficient and the aperture of the capillary hole 44 is fine enough, the real environment gas can be simulated to the maximum extent, so that the gas sample from the capillary hole 41 can contact the electrode of the electrochemical sensor 1 like real environment gas, thereby effectively improving the accuracy of the electrochemical sensor 1 in measuring the concentration of the measured substance contained in the gas sample.

[0058] It should be further noted that the gas sample entering the filter air chamber 4 has been dehydrated by the dehydration step, and in order to make the electrode of the electrochemical sensor 1 contact the gas sample from the capillary hole 44 faster and better, the filter screen of the electrochemical sensor 1 can be removed in the present application.

[0059] It should be further noted that in this embodiment, the inside of each protrusion 43 actually forms a conical small cavity, and after the gas sample enters the cavity 41 for filtering, it further enters each conical small cavity, which plays a role in rectifying and filtering the gas sample, therefore, the plurality of uniformly arranged protrusions 43 form a conical small cavity array, which greatly improves the rectifying and filtering effect of the present application.

[0060] It should be further noted that in one embodiment, the capillary hole 44 is directly arranged on the upper surface of the filter air chamber 4, and the capillary hole 44 sprays the gas sample in the filter air chamber 4. In this embodiment, a conical small cavity array is not formed, and the rectifying and filtering effect of this embodiment is not as good as that of the previous embodiment.

[0061] ​It should be noted that in one embodiment, the filter gas chamber 4 is a structure with an open bottom, and the gas sample enters the lower side of the filter gas chamber 4 from the inlet 42. At this time, since the base 2 is provided with a Peltier module 21, the temperature of the gas sample entering from the inlet 42 can be controlled by the Peltier module 21. For example, in winter, the temperature of the gas sample may be low, and the gas sample needs to be warmed up. In summer, the temperature of the gas sample is relatively high, and the gas sample needs to be cooled down, so that the temperature of the gas sample is suitable for the temperature range of the electrochemical sensor 1. Therefore, in this embodiment, referring to Figure 4 , the filter gas chamber 4 is a structure with an open side, and the other side has a plurality of uniformly arranged protrusions 43 and capillary holes 44. The filter gas chamber 4 cooperates with the base 2 to close the open side.

[0062] In one embodiment, referring to Figure 3 , the base 2 and the shell 3 are connected to each other to form a vacuum structure 5. The purpose of such arrangement is to minimize heat conduction. The vacuum structure is a structure with extremely low thermal conductivity.

[0063] In one embodiment, referring to Figure 3 , the heat conduction module 22 is an aluminum-based heat dissipation fin. In order to improve the heat conduction performance of the heat conduction module 22, a convection fan can also be arranged on the heat conduction module 22.

[0064] In one embodiment, referring to Figure 3 , the gas sample is subjected to water removal before entering the filter gas chamber 4. Since humidity is a major factor affecting the service life of the electrochemical sensor 1, the gas sample needs to be dehydrated before being detected by the electrochemical sensor 1.

[0065] In one embodiment, referring to Figure 3 , the filter gas chamber 4 is further provided with a partition plate 45, the inlet 42 is arranged on the lower side of the partition plate 45, and the upper surface and the lower surface of the partition plate 45 are uniformly provided with round holes (not shown in the figure). By arranging the partition plate 45 in the filter gas chamber 4, and uniformly arranging the round holes on the partition plate 45, when the gas sample enters the lower side of the partition plate 45, it will be dispersed to the upper side of the partition plate 45 through the round holes. Therefore, since the gas sample is in a flowing state under the driving of the air pump, the air flow pulsation generated by the air pump is subjected to first-order rectification filtering under the action of the round holes of the partition plate 45, which greatly reduces the air flow pulsation of the gas sample, and helps to improve the accuracy of the detection of the electrochemical sensor on the gas sample. That is, the protrusions 43 and the capillary holes 44 are the second-order rectification filtering of the gas sample.

[0066] In one embodiment, a temperature sensor (not shown in the figure) is arranged between the filter air chamber 4 and the electrochemical sensor 1, and is used to detect the temperature information of the gas sample sprayed from the capillary hole 44. Therefore, the refrigeration or heating power of the Peltier module 21 is adjusted in time according to the temperature information detected by the temperature sensor, so that the electrochemical sensor 1 can work in an optimal temperature state, thereby effectively improving the accuracy of the electrochemical sensor detection.

[0067] In one embodiment, a humidity sensor (not shown in the figure) is arranged between the filter air chamber 4 and the electrochemical sensor 1, and is used to detect the humidity information of the gas sample sprayed from the capillary hole 44. It is required that the humidity of the gas sprayed from the capillary hole 44 cannot exceed a set value (for example, the relative humidity is 60% RH). If the set value is exceeded, it indicates that the water removal function of the water removal device cannot achieve the application water removal effect, and the water removal device needs to be maintained.

[0068] In one embodiment, referring to Figure 3 , the housing 3 is internally provided with a mounting plate 6, and the electrochemical sensor 1 is mounted on the mounting plate 6. The mounting plate 6 is a mounting plate made of heat insulation material. Through the mounting plate 6, the installation of the electrochemical sensor 1 can be facilitated.

[0069] The above only discloses the preferred embodiments of the present application, and of course cannot limit the scope of the rights of the present application. Therefore, any equivalent changes made within the scope of the patent application of the present application are still within the scope of the present application.

Claims

1. A micro air station, characterized by, The utility model relates to a temperature control box, solenoid valve module and a plurality of electrochemical sensor assembly structures, and relates to a temperature control box, solenoid valve module and a plurality of electrochemical sensor assembly structures. The temperature control box comprises a box body and a box cover, the box cover is sealably covered on the box body, and a plurality of electrochemical sensor assembly structures are assembled in the temperature control box. The solenoid valve module is arranged outside the temperature control box, and a gas sample can be communicated with one or more of the electrochemical sensor assembly structures through the solenoid valve module. The electrochemical sensor assembly structure comprises an electrochemical sensor, a base, a shell and a filter air chamber, the shell is connected to the base, and the electrochemical sensor is arranged in the shell. The filter air chamber is arranged inside the shell and below the electrochemical sensor, the filter air chamber is a hollow structure forming a cavity, and an inlet is arranged on the left side or the right side. The upper surface of the filter air chamber is uniformly provided with capillary holes, the capillary holes are opposite to the electrodes of the electrochemical sensor, the gas sample enters the cavity from the inlet and is sprayed from the capillary holes to contact the electrodes of the electrochemical sensor. The solenoid valve module has one gas inlet and a plurality of gas outlets, the gas inlet can be controlled to be communicated with one of the plurality of gas outlets, and the plurality of gas outlets are respectively communicated with one of the electrochemical sensor assembly structures. The inside of the filter air chamber is further provided with a partition plate, the inlet is arranged on the lower side of the partition plate, and circular holes are uniformly arranged through the upper surface and the lower surface of the partition plate.

2. The micro air station of claim 1, wherein, The base comprises a peltier module and a heat conduction module, a recess is formed on the upper surface of the heat conduction module, the peltier module is arranged in the recess, and the back of the peltier module is in close contact with the heat conduction module.

3. The micro air station of claim 1, wherein, The upper surface of the filter air chamber is uniformly provided with protrusions, and the end of each protrusion is provided with a capillary hole.

4. The micro air station of claim 1, wherein, The mutual connection between the base and the shell is provided with a vacuum structure.

5. The micro air station of claim 2, wherein, The heat conduction module is an aluminum-based heat dissipation fin.

6. The micro air station of claim 1, wherein, The gas sample is subjected to a water removal device before entering the filter air chamber.

7. The micro air station of claim 1, wherein, A temperature sensor is arranged between the filter air chamber and the electrochemical sensor, and the temperature sensor is used to detect the temperature information of the gas sample sprayed from the capillary holes. A humidity sensor is arranged between the filter air chamber and the electrochemical sensor, and the humidity sensor is used to detect the humidity information of the gas sample sprayed from the capillary holes.

8. The micro air station of claim 1, wherein, An installation plate is arranged in the shell, the electrochemical sensor is installed on the installation plate, and the installation plate is made of a heat insulation material.

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