An oil self-cleaning filter device, sensor protection cover and gas sensor

Abstract

The application provides an oil stain self-cleaning filter device, a sensor protection cover and a gas sensor, which comprises a filter layer I and a filter layer II arranged below the filter layer I; the filter layer I comprises at least two parallel conductors; the filter layer II comprises a plurality of heating resistance wires arranged in space intersection or space interlacing with the conductors, and the heating resistance wires and the conductors are combined into a filter screen; wherein all the odd-numbered conductors are connected in parallel as a conductor group I, all the even-numbered conductors are connected in parallel as a conductor group II, a dielectric constant detection circuit is connected in series between the conductor group I and the conductor group II, and the dielectric constant detection circuit is used for detecting the dielectric constant between the conductors; a temperature adjusting circuit is connected with the heating resistance wires, and is used for adjusting the temperature of the heating resistance wires; the dielectric constant detection circuit and the temperature adjusting circuit are also connected with a controller respectively, and when the dielectric constant exceeds a set dielectric threshold, the controller controls the heating resistance wires to heat to a target temperature through the temperature adjusting circuit, so that the oil stain is gasified.

Description

TECHNICAL FIELD

[0001] The present application relates to a gas sensor, in particular to an oil stain self-cleaning filtering device, a sensor protective cover and a gas sensor. BACKGROUND

[0002] With the development and progress of social economy, natural gas as a clean energy gradually becomes the preferred fuel for each family, which brings us convenience, but gas leakage also causes great safety hazards to people's life and property safety. As the basis for judging the concentration of gas, the sensitivity and accuracy of the detection of the gas sensor play a decisive role.

[0003] The gas sensor is mostly used in the kitchen or other scenes with more oil smoke, but as time goes on, some oil smoke will adhere to the surface of the sensor, causing the sensitivity of the gas sensor to decrease, affecting the accuracy of the detection result of the gas sensor, and causing the gas alarm not to alarm.

[0004] In order to prevent the sensor sensitive body from being damaged, the existing solution is to install a protective cover on the gas sensor to protect the sensitive body of the sensor from being damaged; but in the process of using the gas sensor, as time goes on, the oil smoke will gradually adhere to the protective cover and block the air holes, causing the air in the measured space to be unable to circulate to the surface of the gas sensor, affecting the detection efficiency, and even unable to normally detect the gas concentration in the external air, causing no alarm and explosion accidents, which brings great safety hazards to production and life.

[0005] In order to solve the above problems, people have been seeking an ideal technical solution. SUMMARY

[0006] The purpose of the present application is to overcome the shortcomings of the prior art, and to provide an oil stain self-cleaning filtering device, a sensor protective cover and a gas sensor.

[0007] In order to achieve the above purpose, the technical scheme adopted by the present application is: an oil stain self-cleaning filtering device, comprising a filtering layer I and a filtering layer II arranged below the filtering layer I;

[0008] The filtering layer I comprises at least two parallel arranged conductors; the filtering layer II comprises heating resistance wires arranged in space intersection or space stagger with the conductors, and the heating resistance wires and the conductors are combined into a filtering net;

[0009] Among them, all the odd-numbered conductors are connected in parallel as conductor group I, all the even-numbered conductors are connected in parallel as conductor group II, and a dielectric constant detection circuit is connected in series between the conductor group I and the conductor group II, for detecting the dielectric constant between the conductors;

[0010] A temperature adjusting circuit is connected with the heating resistance wire, and used for adjusting the temperature of the heating resistance wire.

[0011] The dielectric constant detection circuit and the temperature adjusting circuit are respectively connected with a controller, and when the dielectric constant detected by the dielectric constant detection circuit exceeds a set dielectric threshold value, the controller controls the heating resistance wire to heat to a target temperature through the temperature adjusting circuit, so as to gasify the oil stains.

[0012] Optionally, before the heating resistance wire is controlled to heat to the target temperature through the temperature adjusting circuit, the controller calculates the target temperature according to the following formula:

[0013] ;

[0014] Wherein, k represents the kth sampling period, err(k) is the dielectric constant difference of the kth sampling period, T is the sampling interval, err(k-1) is the dielectric constant difference of the (k-1)th sampling period; Kp is the increasing proportional coefficient, T i is the integral coefficient, and T D is the differential coefficient; j is the jth dielectric constant difference in history.

[0015] Optionally, in order to control the heating resistance wire to heat to the target heating temperature, the temperature adjusting circuit comprises a temperature sensor, which is arranged on the heating resistance wire and used for collecting the temperature of the heating resistance wire.

[0016] In actual oil stain removal, due to the influence of the degree of oil stain or the composition of the compound forming the oil stain, there may be a case that the dielectric constant does not change obviously after heating for a period of time, therefore, when the heating resistance wire is controlled to heat to the target temperature through the temperature adjusting circuit, the heating time is accumulated, and when the accumulated heating time exceeds a set time threshold value, it is judged whether the dielectric constant exceeds the set dielectric threshold value and the dielectric change amount is less than a set change amount;

[0017] If the dielectric constant exceeds the set dielectric threshold value and the dielectric change amount is less than the set change amount, the target temperature is increased by a preset compensation temperature, the heating resistance wire is controlled to heat to the adjusted target temperature through the temperature adjusting circuit, and the heating time is accumulated again;

[0018] Otherwise, the heating is stopped, and the dielectric constant between the conductors is detected again.

[0019] The second aspect of the present application provides a sensor protective cover, comprising a protective cover body and a filter device arranged at the air inlet of the protective cover, wherein the filter device is the aforementioned oil stain self-cleaning filter device.

[0020] The third aspect of the present application provides a gas sensor, comprising a gas sensor sensitive body die and a sensor protective cover arranged above or around the gas sensor sensitive body die, wherein the sensor protective cover is the aforementioned sensor protective cover.

[0021] The present application has outstanding substantial features and significant progress compared with the prior art, specifically, the present application uses the heating resistance wire and the conductor arranged in space intersection or space stagger to form the filter device, and uses the dielectric constant detection circuit to detect the dielectric constant between the conductors, and controls the heating resistance wire to heat when the dielectric constant exceeds the set dielectric threshold, so that the oil stains on the conductor and itself are removed by using the method of heating the resistance wire, and the filter device is restored to the clean state, so that the air from the outside is difficult to pass through the filter device, which is ingenious in design, strong in practicality, low in cost, and wide in application range. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is the overall structure schematic diagram of the present application.

[0023] Figure 2 It is the structure schematic diagram of the filter layer I of the present application.

[0024] Figure 3 It is the structure schematic diagram of the filter layer II of the present application.

[0025] Figure 4 It is the structure schematic diagram of the filter layer II after adding the temperature sensor of the present application.

[0026] Figure 5 It is the overall structure schematic diagram after adding the temperature sensor of the present application.

[0027] Figure 6 It is the flow schematic diagram of the present application.

[0028] In the figure: 1. protective cover air inlet; 2. odd number block conductor; 3. even number block conductor; 4. dielectric constant detection circuit; 5. heating resistance wire; 6. temperature adjustment circuit; 7. temperature sensor. DETAILED DESCRIPTION

[0029] The technical solutions of the present application are described in further detail below through specific embodiments.

[0030] Example 1

[0031] The present embodiment provides an oil stain self-cleaning filter device, which comprises a filter layer I and a filter layer II arranged below the filter layer I, the filter layer I comprises at least two parallel arranged conductors; the filter layer II comprises a heating resistance wire 5 arranged in space intersection or space stagger with the conductors, and the heating resistance wire 5 and the conductors are combined into a filter net.

[0032] Specifically, the heating resistance wire 5 of the filter layer II and the conductor group I and the conductor group II form a cross arrangement or a spatially staggered arrangement of a grid structure.

[0033] In an embodiment, the heating resistance wire 5 is a straight heating resistance wire arranged in parallel.

[0034] When the heating resistance wire 5 arranged in parallel and the conductor arranged in parallel are spatially staggered, the heating resistance wire 5 and the conductor can form a cross grid-shaped filter screen, thereby achieving a filtering function.

[0035] Further, it can be understood that when the heating resistance wire 5 arranged in parallel and the conductor arranged in parallel are spatially perpendicular, the heating resistance wire 5 and the conductor can form a cross grid-shaped filter screen, at which time the filtering effect is the best.

[0036] When the heating resistance wire 5 arranged in parallel and the conductor arranged in parallel are spatially staggered, each heating resistance wire 5 is arranged at a lower side between any two adjacent conductors, at which time the heating resistance wire 5 and the conductor form a one-way filter screen, which can also achieve a filtering function.

[0037] It can be understood that in order to facilitate heating management, a plurality of heating resistance wires 5 can also be connected through the conductor, wherein when one end of each heating resistance wire is connected to the same end of the previous heating resistance wire and the other end of each heating resistance wire is connected to the same end of the subsequent heating resistance wire, an S-shaped structure is formed; when one end of each heating resistance wire is connected to the opposite end of the previous heating resistance wire and the other end of each heating resistance wire is connected to the opposite end of the subsequent heating resistance wire, a Z-shaped structure is formed.

[0038] In an embodiment, the heating resistance wire 5 can be a triangular zigzag heating resistance wire, a plurality of triangular zigzag heating resistance wires are connected in sequence, and the triangular zigzag heating resistance wire and the conductor can form a cross grid-shaped filter screen, thereby achieving a filtering function.

[0039] In another embodiment, the heating resistance wire 5 is a cross grid structure, at which time the heating resistance wire 5 cooperates with the conductor to achieve a filtering effect.

[0040] Further, all odd-numbered conductors 2 in the direction perpendicular to the conductor are connected in parallel as the conductor group I, all even-numbered conductors 3 in the direction perpendicular to the conductor are connected in parallel as the conductor group II, and then the dielectric constant detection circuit 4 is connected in series between the conductor group I and the conductor group II to detect the dielectric constant between the conductors.

[0041] If there is no external environmental interference, the dielectric constant of the conductor should be a fixed value, and as the oil fume and other sundries gradually fall on the conductor, the dielectric constant of the conductor will change. Therefore, the dielectric constant value is selected as the basis for whether the oil stain self-cleaning needs to be started and how to perform the oil stain self-cleaning in this embodiment.

[0042] Specifically, the dielectric constant detection circuit 4 can select any method that can realize the function of dielectric constant detection, such as the capacitive method dielectric constant test. Since it is not the technical point to be protected in this application, it is not particularly limited here, and a common dielectric constant detection circuit can be directly selected.

[0043] In order to realize the oil stain self-cleaning, a temperature adjusting circuit 6 is further provided, which is connected with the heating resistance wire 5 and used for adjusting the temperature of the heating resistance wire 5.

[0044] Further, the dielectric constant detection circuit 4 and the temperature adjusting circuit 6 are further connected with a controller respectively, and the controller controls the heating resistance wire 5 to heat to a target temperature through the temperature adjusting circuit when the dielectric constant detected by the dielectric constant detection circuit 4 exceeds a set dielectric threshold value, so as to gasify the oil stain on the filter screen.

[0045] Specifically, when the dielectric constant detection circuit 4 detects that the dielectric constant of the conductor changes by more than the set dielectric threshold value, the severity of the oil stain is judged, at this time, it is represented that the filter screen between the filter screens may have been blocked, so the heating resistance wire 5 needs to be used to heat to perform the oil stain cleaning operation on the filter screen.

[0046] It can be understood that the set dielectric threshold value can be set according to the application occasion and user demand, when it is needed to keep the cleanliness of the filter screen in real time, the set dielectric threshold value can be set smaller, so that when the dielectric constant changes slightly, the heating resistance wire 5 is controlled to heat to perform the oil stain cleaning operation on the filter screen. When the purpose is not to block the filter screen between the filter screens, the set dielectric threshold value can be set larger, so that only when the dielectric constant has changed greatly, the heating resistance wire 5 is controlled to heat to perform the oil stain cleaning operation on the filter screen.

[0047] In actual operation, the kitchen oil fume is a large amount of thermal oxidative decomposition product produced under high temperature conditions of edible oil and food, the main components are aldehyde, ketone, hydrocarbon, fatty acid, alcohol, aromatic compound, ester, lactone, heterocyclic compound, etc., and the volatilization temperature is between 170-300 degrees Celsius. The ignition point of the main component methane of natural gas is 538℃, which is much higher than the volatilization temperature of the oil stain and other substances affecting the permeability of the protective cover.

[0048] Therefore, when the filter screen is cleaned by the oil stains using the heating method of the heating resistance wire 5, the temperature of the heating resistance wire 5 needs to be controlled to be between 170-500℃, so that the oil stains and other substances adhered to the protective cover can be removed.

[0049] However, because the oil stains are different, the main compounds causing the oil stains are different, and therefore the required heating temperature is also different, so before the heating resistance wire 5 is heated to the target temperature by the temperature adjustment circuit, the controller also calculates the target temperature according to the dielectric constant value.

[0050] The specific calculation formula is: .

[0051] Wherein, k represents the kth sampling period, err(k) is the dielectric constant difference of the kth sampling period, T is the sampling interval, err(k-1) is the dielectric constant difference of the k-1th sampling period; Kp is the increase ratio coefficient, T i is the integral coefficient, T D is the differential coefficient; j is the jth historical dielectric constant difference.

[0052] Further, in order to control the heating resistance wire 5 to be able to heat to the target temperature, the temperature adjustment circuit 6 further comprises a temperature sensor 7, which is arranged on the heating resistance wire 5 and is used to collect the temperature of the heating resistance wire 5. The heating resistance wire is heated to the target temperature through the temperature feedback of the temperature sensor 7.

[0053] In actual oil stain removal, due to the influence of the main compounds of the oil stains, it is possible that the dielectric constant does not change obviously after heating for a period of time, so as shown in Figure 6 When the heating resistance wire 5 is heated to the target temperature by the temperature adjustment circuit 6, the heating time is accumulated, and when the accumulated heating time exceeds the set time threshold, it is judged whether the dielectric constant exceeds the set dielectric threshold and the dielectric change amount is less than the set change amount.

[0054] If the dielectric constant exceeds the set dielectric threshold and the dielectric change amount is less than the set change amount, the target temperature is increased by a preset compensation temperature, and the heating resistance wire is heated to the adjusted target temperature by the temperature adjustment circuit, and the heating time is accumulated again.

[0055] Otherwise, stop heating and re-detect the dielectric constant between the conductors.

[0056] It should be noted that when the dielectric constant exceeds the set dielectric threshold and the dielectric change amount is less than the set change amount, it means that the oil stain on the conductor is not removed at this temperature, and the reason why it is not removed is that the volatilization temperature of the compound in the oil stain has not been reached, so the target temperature needs to be raised, and the time is reset.

[0057] Preferably, the preset compensation temperature is a fixed value a, which can be 20°C or 50°C, etc.

[0058] It can be understood that before the temperature adjustment circuit 6 controls the heating resistance wire to heat to the adjusted target temperature, it is first determined whether the adjusted target temperature (original target temperature + preset compensation temperature) exceeds the set temperature threshold. If it does not exceed, the heating resistance wire is heated to the adjusted target temperature by the temperature adjustment circuit; otherwise, the set temperature threshold is used as the target temperature, and the heating resistance wire is heated to the adjusted target temperature by the temperature adjustment circuit.

[0059] The reason for heating at the set temperature threshold when the adjusted target temperature exceeds the set temperature threshold is that when the temperature exceeds the set temperature, an explosion event is likely to occur, affecting the safety of the oil stain self-cleaning filter device.

[0060] For example, the ignition point of methane is 538°C. If the temperature of the heating resistance wire 5 approaches or is higher than 538°C, an explosion event is likely to occur. Therefore, the resistance wire temperature needs to be controlled to be lower than the methane ignition point of 538°C. For example, the set temperature threshold is set to 500°C, so that the combustible impurities on the surface of the filter screen are evaporated to improve the permeability of the protective cover, and the safety of the gas sensor is not affected.

[0061] In addition, it should be noted that due to the aging of the dielectric constant detection circuit 4, the initial dielectric constant may be too high or too low.

[0062] Therefore, when the system is initialized, the heating resistance wire 5 is controlled to heat at a set temperature such as 500°C for a set time such as 5 minutes, the dielectric constant detected by the dielectric constant detection circuit 4 is taken as the initial dielectric constant, and the dielectric threshold is set according to the initial dielectric constant.

[0063] Similarly, if the dielectric constant still exceeds the set dielectric threshold and the dielectric change amount is less than the set change amount after continuously heating the heating resistance wire 5 at the set temperature threshold for the set time threshold, the initial dielectric constant is recalibrated, the real-time dielectric constant detected by the dielectric constant detection circuit 4 is taken as the initial dielectric constant, and the set dielectric threshold is recalculated; otherwise, stop heating and re-detect the dielectric constant between the conductors.

[0064] Example 2

[0065] The embodiment provides a sensor protective cover, which comprises a protective cover body and a filter device arranged at the air inlet 1 of the protective cover, wherein the filter device is the oil stain self-cleaning filter device in the embodiment 1.

[0066] Embodiment 3

[0067] The embodiment provides a gas sensor, which comprises a gas sensor sensitive body pipe core and a sensor protective cover arranged above or around the gas sensor sensitive body pipe core, wherein the sensor protective cover is the sensor protective cover in the embodiment 2.

[0068] The gas sensor with the oil stain self-cleaning function can detect the pollution degree of the protective cover by detecting the dielectric constant of the conductor, and can clean the protective cover by using a resistance wire heating, so that the problems that the protective cover is difficult to clean, the outside air is difficult to enter the inside of the gas detection sensor device, the long-term exposure environment has a bad influence on the sensitivity of the gas sensitive sensor, the gas sensitive sensor cannot provide clean detection conditions for a long time, and the detection result of the gas sensor is not accurate can be solved, the service life of the device is prolonged, and the accuracy of the detection result of the gas sensor is ensured.

[0069] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application rather than limit them; although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the specific embodiments of the present application can be modified or some technical features can be replaced by equivalent ones; without departing from the spirit of the technical solutions of the present application, they should be covered in the technical solution range of the present application claimed.

Claims

1. An oil-stain self-cleaning filter device, characterized in that: It includes filter layer I and filter layer II disposed below filter layer I; The filter layer I includes at least two parallel conductors; the filter layer II includes a plurality of heating resistance wires that are spatially intersecting or staggered with the conductors, and the heating resistance wires and the conductors are combined to form a filter screen. In this configuration, all odd-numbered conductors are connected in parallel to form conductor group I, and all even-numbered conductors are connected in parallel to form conductor group II. A dielectric constant detection circuit is connected in series between conductor group I and conductor group II to detect the dielectric constant between the conductors. A temperature regulation circuit is connected to the heating resistance wire and is used to regulate the temperature of the heating resistance wire; The dielectric constant detection circuit and the temperature regulation circuit are also connected to the controller. When the dielectric constant detected by the dielectric constant detection circuit exceeds the set dielectric threshold, the controller controls the heating resistance wire to heat to the target temperature through the temperature regulation circuit in order to vaporize the oil. Before the heating resistance wire is heated to the target temperature by the temperature regulation circuit, the controller calculates the target temperature according to the following formula; ； Where k represents the kth sampling period, err(k) is the dielectric constant difference of the kth sampling period, T is the sampling interval, err(k-1) is the dielectric constant difference of the (k-1)th sampling period; Kp is the scaling factor, T i T is the integral coefficient. D is the differential coefficient; j is the j-th dielectric constant difference in history; When the heating resistance wire is heated to the target temperature by the temperature regulation circuit, the heating time is accumulated, and when the accumulated heating time exceeds the set time threshold, it is determined whether the dielectric constant exceeds the set dielectric threshold and whether the dielectric change is less than the set change. If the dielectric constant exceeds the set dielectric threshold and the dielectric change is less than the set change, the target temperature is raised to a preset compensation temperature, and the heating resistance wire is controlled by the temperature regulation circuit to heat to the adjusted target temperature, and the heating time is accumulated again. Otherwise, stop heating and retest the dielectric constant between the conductors; Before the heating resistance wire is heated to the adjusted target temperature by the temperature regulation circuit, it is first determined whether the adjusted target temperature exceeds the set temperature threshold. If it does not exceed the threshold, the heating resistance wire is heated to the adjusted target temperature by the temperature regulation circuit; otherwise, the set temperature threshold is used as the target temperature, and the heating resistance wire is heated to the adjusted target temperature by the temperature regulation circuit.

2. The self-cleaning oil filter device according to claim 1, characterized in that: The heating resistance wire, conductor group I, and conductor group II form a grid structure that is either intersected or spatially staggered.

3. The oil stain self-cleaning filter device according to claim 1, characterized in that: The heating resistance wire has a cross-grid structure.

4. The oil stain self-cleaning filter device according to claim 1, characterized in that: The temperature regulation circuit includes a temperature sensor, which is mounted on the heating resistance wire and is used to collect and feed back the temperature of the heating resistance wire to the controller.

5. The self-cleaning oil filter device according to claim 1, characterized in that: During system initialization, the heating resistance wire is controlled to heat at a set temperature for a set time. The dielectric constant detected by the dielectric constant detection circuit is used as the initial dielectric constant, and the dielectric threshold is set according to the initial dielectric constant. If, after the heating resistance wire is heated to a set temperature threshold for a set time threshold, the dielectric constant still exceeds the set dielectric threshold and the dielectric change is less than the set change, then the initial dielectric constant is recalibrated, the real-time dielectric constant detected by the dielectric constant detection circuit is used as the initial dielectric constant, and the set dielectric threshold is recalculated; otherwise, heating is stopped, and the dielectric constant between the conductors is re-detected.

6. A sensor protective cover, characterized in that: It includes a protective cover body and a filter device disposed at the air inlet of the protective cover, wherein the filter device is the oil stain self-cleaning filter device according to any one of claims 1 to 5.

7. A gas sensor, characterized in that: It includes a gas sensor sensing element core and a sensor protective cover disposed above or around the gas sensor sensing element core, wherein the sensor protective cover is the sensor protective cover as described in claim 6.

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