Micro differential pressure airflow sensor integrated with temperature and humidity compensation

Abstract

This invention relates to the field of airflow sensor technology, specifically to a micro-differential pressure airflow sensor with integrated temperature and humidity compensation. It includes a humidity control component, a pressure transmission component, an output component, and a controller. The pressure transmission component is installed at the lower end of the housing, and the output component is installed inside the pressure transmission component. The lower humidity control component is connected to the inside of a throttling element and communicates with the inside of the pressure transmission component. When detecting airflow, the pressure transmission component guides the air pressure at both ends to the output component. Simultaneously, the humidity control component guides droplets from the surface of the throttling element to the pressure transmission component, causing the output component to change its output value. The output component generates a voltage signal based on the pressure difference and outputs the final signal through the controller. This solves the problem that in low-temperature, high-humidity environments, high-humidity gas forms droplets on the surface of mesh air resistance and perforated plates, affecting detection accuracy, and that droplets adhering to the surface of the temperature probe change the thermal conductivity of the temperature probe surface material.

Description

Technical Field

[0001] This invention relates to the field of airflow sensor technology, and more specifically to a micro-differential pressure airflow sensor with integrated temperature and humidity compensation. Background Technology

[0002] Airflow sensors are a type of intelligent sensor. Due to their high precision, real-time monitoring, and strong environmental adaptability, they are widely used in core fields such as medical, industrial, automotive, and environmental monitoring. Their working principle is that when a flow is throttling through a device (such as a mesh air resistance or orifice plate), a pressure difference is formed on both sides of the throttling device due to the Bernoulli effect. The greater the flow rate, the greater the pressure difference. The pressure difference drives the middle part of the diaphragm to shift to the low-pressure side, thereby producing deformation. The deformation of the diaphragm causes the resistance of the strain gauge attached to the diaphragm to change, thereby outputting a voltage signal.

[0003] As temperature increases, gas density decreases, resulting in a decrease in the differential pressure output of the differential pressure airflow sensor at the same flow rate. Furthermore, temperature changes alter the deformation of the diaphragm, directly affecting its curvature and further reducing the sensor's detection accuracy. Existing technologies address this by placing temperature and humidity sensors at both ends of the throttling device. By detecting the temperature and humidity in the air and using algorithms to compensate for the airflow sensor's detection results, the voltage signal output by the airflow sensor is corrected, thereby improving the sensor's output accuracy.

[0004] However, when used for detecting exhaust volume in high-humidity environments, such as in ventilators where airflow sensors detect patient breathing, the humidity is high during patient respiration. When the ambient temperature is low and the internal temperature of the airflow sensor is below the dew point, high-humidity gas entering the airflow sensor may, over time, form droplets on the surface of the mesh air resistance and orifice plate. This alters the airflow direction and orifice size within the sensor, affecting its detection accuracy. Since droplet accumulation on the orifice plate surface is a continuous and irregular process, algorithms alone cannot accurately compensate for it. Furthermore, when droplets adhere to the surface of the temperature probe, they change the thermal conductivity of the probe's surface material, affecting its detection accuracy and leading to inaccurate algorithm compensation.

[0005] In view of the above, in order to overcome the above technical problems, the present invention designs a micro-differential pressure airflow sensor with integrated temperature and humidity compensation, which solves the above technical problems. Summary of the Invention

[0006] This invention provides a micro-differential pressure airflow sensor with integrated temperature and humidity compensation. It utilizes a pressure transmission component to transfer air pressure from both ends of the airflow sensor to the output component. Simultaneously, a humidity control component prevents droplet accumulation on the throttling element and compensates for humidity in the output component. By setting two sets of different metal diaphragms in the output component, the internal temperature of the airflow sensor is calculated by comparing their different degrees of curvature at the same temperature. The temperature is then compensated by a controller, and the final signal is output. This method solves the problems in low-temperature, high-humidity environments where high-humidity gas forms droplets on the surface of the mesh air resistance and orifice plate, affecting detection accuracy, and where droplets adhering to the temperature probe surface alters the thermal conductivity of the temperature probe surface material.

[0007] A micro-differential pressure airflow sensor with integrated temperature and humidity compensation includes a housing, an air inlet, an air outlet, a throttling element, a humidity control component, a pressure transmission component, an output component, and a controller. The air inlet and air outlet are connected to the front and rear ends of the housing, respectively. The throttling element is connected inside the housing. The pressure transmission component is installed at the lower end of the housing and is connected to the front and rear ends of the housing. The output component is installed inside the pressure transmission component. The humidity control component at the lower end is connected to the inside of the throttling element and communicates with the inside of the pressure transmission component. When detecting airflow, the pressure transmission component guides the air pressure at the front and rear ends to the output component. At the same time, the humidity control component guides the liquid droplets on the surface of the throttling element to the pressure transmission component and drives the output component to change the output value. The output component generates a voltage signal based on the pressure difference and outputs the final signal through the controller.

[0008] Preferably, the pneumatic transmission assembly includes a connecting pipe, a connecting valve, and a pneumatic chamber. The pneumatic chamber is installed at the lower end of the outer casing, and the connecting valve is installed inside the connecting pipe. The two connecting pipes respectively connect the outer casing to the front and rear ends of the pneumatic chamber. The pneumatic chamber is divided into a diversion chamber, a left detection chamber, and a right detection chamber. The diversion chamber is located at the front and rear ends of the pneumatic chamber and is connected to the connecting pipe. The left and right detection chambers are located on the left and right sides of the pneumatic chamber and are respectively connected to the diversion chambers at the front and rear ends.

[0009] Preferably, a double-layer filter screen is installed in the diversion cavity, and a water-absorbing filter element is installed between the double-layer filter screen.

[0010] Preferably, the throttling element has multiple water inlet grooves on its surface and a water storage cavity inside it. The water inlet grooves are connected to the water storage cavity, and a guide plate is installed in the water storage cavity.

[0011] Preferably, the throttling device has a boss at its front end, and the front end of the boss has a rounded corner.

[0012] Preferably, the output component includes a first metal diaphragm, a second metal diaphragm, a power supply, and resistance strain gauges. The first metal diaphragm and the second metal diaphragm are respectively fixed in the middle of the left and right detection cavities and are tightly fitted to the inner walls of the left and right detection cavities. The power supply is installed at the upper end of the pressure chamber. Multiple resistance strain gauges are attached to the surfaces of the first metal diaphragm and the second metal diaphragm and are electrically connected to the power supply.

[0013] Preferably, the humidity control component includes a water guide pipe, an installation pipe, a water absorption expansion component, and a compensating link. The water guide pipe connects to multiple throttling components and is connected to a water storage chamber. The installation pipe is installed between the double-layer filter screens. The water absorption expansion component is installed inside the installation pipe. One end of the compensating link is slidably installed inside the installation pipe, and the other end is connected to the outside of the metal diaphragm.

[0014] Preferably, a heating element is installed at the contact portion between the mounting tube and the water-absorbing expansion member, and a solenoid valve is installed at the top of the mounting tube.

[0015] The beneficial effects of this invention are as follows:

[0016] 1. Compared to traditional airflow sensors that monitor internal temperature and humidity using temperature and humidity sensors and compensate using algorithms, this solution uses a pressure transmission component and an output component to calculate the internal temperature of the airflow sensor by comparing two sets of metal diaphragms. This solves the problem that droplets adhering to the surface of the temperature probe will change the thermal conductivity of the surface material of the temperature probe, thus affecting the detection accuracy. At the same time, by setting up a humidity control component, droplets formed on the surface of the mesh air resistance and the perforated plate are removed while compensating the output component. This solves the problem that in low-temperature and high-humidity environments, high-humidity gas will form droplets on the surface of the mesh air resistance and the perforated plate, thus affecting the detection accuracy.

[0017] 2. This invention, by setting up a pressure transmission component and an output component, and by setting two sets of metal diaphragms of different materials in the output component, calculates the internal temperature of the airflow sensor by the difference in the degree of bending of the two sets of metal diaphragms under the same pressure difference and temperature. The calculated temperature is then used to compensate one set of signals through a controller, achieving precise temperature compensation for the airflow sensor. This solution avoids the problem of inaccurate measurements due to changes in heat transfer rate caused by excessive humidity and droplets adhering to the temperature probe surface, thus improving the accuracy of the airflow sensor.

[0018] 3. This invention utilizes a humidity control component, incorporating a water-absorbing expansion element within the pressure transmission component and a water-guiding groove within the throttling element. This allows for the adsorption of droplets from the surface of the throttling element into the humidity control component. Furthermore, by controlling the material and quantity of the water-absorbing expansion element, the deformation of the expansion element is controlled, thereby providing precise humidity compensation for the output component. This solution prevents droplets from adhering to the surface of the throttling element, thus reducing its aperture and affecting the accuracy of the airflow sensor. Additionally, by connecting the water-absorbing expansion element to the water-absorbing filter element in the double-layer filter, moisture inside the pressure transmission component can be filtered out, reducing water vapor corrosion when it comes into contact with the metal diaphragm. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] The above and other aspects of the invention will now be described by way of example only, with reference to the accompanying drawings, in which:

[0021] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0022] Figure 2 This is a schematic diagram of the overall structure of the throttling device of the present invention;

[0023] Figure 3 This is a cross-sectional view of the throttling element of the present invention, shown from the axial side.

[0024] Figure 4 This is a front view of the present invention;

[0025] Figure 5 This is the present invention. Figure 4 Axonometric view of the cross-section of section AA in the middle;

[0026] Figure 6 This is the present invention. Figure 4 Axonometric view of the cross-section of section BB;

[0027] Figure 7 This is the present invention. Figure 5 Enlarged view of section C;

[0028] Figure 8 This is a schematic diagram of the temperature compensation principle of the present invention.

[0029] In the picture:

[0030] 1. Outer shell;

[0031] 2. Air inlet;

[0032] 3. Air outlet;

[0033] 4. Throttling element; 41. Water inlet channel; 42. Water storage chamber; 43. Baffle plate; 44. Boss;

[0034] 5. Humidity control components; 51. Water guide pipe; 52. Installation pipe; 521. Heating element; 522. Solenoid valve; 53. Water absorption expansion component;

[0035] 54. Compensation link;

[0036] 6. Pneumatic pressure transmission assembly; 61. Connecting pipe; 62. Connecting valve; 63. Pneumatic pressure chamber; 631. Diverting chamber; 632. Left detection chamber; 633. Right detection chamber; 634. Double-layer filter screen;

[0037] 7. Output components; 71. Metal diaphragm one; 72. Metal diaphragm two; 73. Power supply; 74. Resistance strain gauge;

[0038] 8. Regulator. Detailed Implementation

[0039] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0040] As one embodiment of the present invention, refer to Figures 1 to 8A micro-pressure differential airflow sensor with integrated temperature and humidity compensation includes a housing 1, an air inlet 2, an air outlet 3, a throttling device 4, a humidity control component 5, a pressure transmission component 6, an output component 7, and a controller 8. The air inlet 2 and air outlet 3 are connected to the front and rear ends of the housing 1, respectively, and communicate with external equipment that needs to detect airflow. The throttling device 4 is fixedly installed inside the housing 1. When airflow occurs, the throttling device 4 reduces the orifice size of the gas flow, increasing its velocity relative to the air inlet 2, thus creating a pressure difference between the air inlet 2 and the air outlet 3. The pressure transmission component 6 is installed at the lower end of the housing 1 and communicates with the front and rear ends of the housing 1. The gas at the air inlet 2 and air outlet 3 is transmitted to the output component 7 through the pressure transmission component 6, and the gas pressure directly acts on the output component 7. The output component 7 is equipped with... Inside the pressure transmission assembly 6, the output assembly 7 deforms due to the pressure difference between the two sides, thereby generating a voltage signal. The humidity control assembly 5 is connected inside the throttling element 4 to adsorb water droplets that have accumulated on the surface of the throttling element 4. At the same time, the humidity control assembly 5 is connected to the pressure transmission assembly 6 to perform humidity compensation on the output assembly 7. When detecting airflow, the pressure transmission assembly 6 transmits the air pressure at both ends of the airflow sensor to the output assembly 7. Meanwhile, the humidity control assembly 5 adsorbs the water droplets on the surface of the throttling element 4 and transmits them to the pressure transmission assembly 6, thereby driving the output assembly 7 to change its deformation and thus perform humidity compensation. The output assembly 7 deforms according to the pressure difference between the two ends and outputs a voltage signal after humidity compensation. The voltage signal is then temperature compensated by the controller 8 before outputting the final signal.

[0041] As one embodiment of the present invention, refer to Figure 4 , Figure 6The air pressure transmission component 6 includes a connecting pipe 61, a connecting valve 62, and an air pressure chamber 63. The air pressure chamber 63 is installed at the lower end of the outer casing 1 and is a sealed box used to install the output component 7 and generate an air pressure difference on both sides of the output component 7. Two connecting pipes 61 connect the outer casing 1 to the front and rear ends of the air pressure chamber 63, respectively. The connection points of the two connecting pipes 61 and the outer casing 1 are located at the front and rear ends of the throttling device 4, respectively responsible for transmitting the air pressure from the air inlet 2 and the air outlet 3 to the air pressure chamber 63, forming an air pressure difference on both sides of the output component 7. The connecting valve 62 is installed inside the connecting pipe 61. When the airflow sensor is working, the connecting valve 62 is open. When the airflow sensor is not working, the connecting valve 62 is closed to prevent external moisture from continuously entering the air pressure chamber 63. The air pressure chamber 63 is divided into a diversion chamber 631 and a left detection chamber. The right detection chamber 632 and the right detection chamber 633, and the flow divider chamber 631 are located at the front and rear ends of the pressure chamber 63 and are connected to the connecting pipe 61. The left detection chamber 632 and the right detection chamber 633 are located on the left and right sides of the pressure chamber 63 and are connected to the flow divider chambers 631 at the front and rear ends, respectively. When gas enters the airflow sensor, it will enter the flow divider chamber 631 through the connecting pipe 61 and then enter the left detection chamber 632 and the right detection chamber 633 through the flow divider chamber 631, so that the air pressure of the left detection chamber 632 and the right detection chamber 633 is consistent with the air pressure of the corresponding connecting pipe 61. In this way, two detection chambers with the same temperature and the same air pressure at both ends can be formed, so that the output component 7 has the same detection environment in the left detection chamber 632 and the right detection chamber 633.

[0042] As one embodiment of the present invention, refer to Figure 6 A double-layer filter 634 is installed inside the diversion chamber 631, and a water-absorbing filter element is installed between the double-layer filter 634. The connection between the connecting pipe 61 and the diversion chamber 631 is located below the double-layer filter 634, while the connection between the diversion chamber 631 and the left detection chamber 632 and the right detection chamber 633 is located above the double-layer filter 634. When gas passes through the double-layer filter 634 and enters the left detection chamber 632 and the right detection chamber 633, the water-absorbing filter element removes the moisture, preventing high humidity air from entering the detection chamber and corroding the internal components of the output component 7, thus reducing its accuracy.

[0043] As one embodiment of the present invention, refer to Figure 2 , Figure 3The throttling device 4 has multiple water-guiding grooves 41 on its surface and a water storage cavity 42 inside. The water-guiding grooves 41 are connected to the water storage cavity 42, and a guide plate 43 is installed in the water storage cavity 42. The surface of the water-guiding grooves 41 is made of a hydrophilic material. The water-guiding grooves 41 are located on the surface of the throttling device 4, and the surface of the throttling device 4 has an inclined surface with the water-guiding grooves 41 as the center. When droplets condense on the surface of the throttling device 4, they are adsorbed into the water-guiding grooves 41 by the hydrophilic material. Since the water-guiding grooves 41 are connected to the water storage cavity 42, the water-guiding device 41 is connected to the water storage cavity 42. In the water storage chamber 42, droplets will enter the water storage chamber 42 along the water inlet channel 41, and at the same time, they will drip onto the guide plate 43 installed in the water storage chamber 42. The surface of the guide plate 43 is made of smooth material. The droplets slide along the guide plate 43 to the end of the guide plate 43. Through this solution, when water vapor forms droplets on the surface of the throttling device 4, it will be adsorbed by the water inlet channel 41 and enter the water storage chamber 42, avoiding the droplets from staying on the throttling device 4, affecting the airflow direction inside the airflow sensor and changing the orifice size of the throttling device 4.

[0044] As one embodiment of the present invention, refer to Figure 3 A boss 44 is installed at the front end of the throttling device 4. The front end of the boss 44 is a rounded corner. When the airflow passes through the boss 44 at the front end of the throttling device 4, the airflow will change its direction of movement along the rounded corner of the front end of the boss 44 because the front end of the boss 44 is a rounded corner. This will cause the airflow to adhere to the sides of the throttling device 4 on the upper and lower sides, thus pushing the droplets on the surface of the throttling device 4 on the upper and lower sides into the water inlet trough 41.

[0045] As one embodiment of the present invention, refer to Figure 5 , Figure 6 and Figure 7The output component 7 includes a first metal diaphragm 71, a second metal diaphragm 72, a power supply 73, and resistance strain gauges 74. The first metal diaphragm 71 and the second metal diaphragm 72 are fixed in the middle of the left detection chamber 632 and the right detection chamber 633, respectively. The first metal diaphragm 71 and the second metal diaphragm 72 are made of different types of metals, and their deformation varies significantly with temperature. The first metal diaphragm 71 and the second metal diaphragm 72 are tightly fitted to the inner walls of the left and right detection chambers 632 and 633, preventing gas from passing through the gaps between the two ends. The power supply 73 is installed at the upper end of the pressure chamber 63 and supplies power to the resistance strain gauges 74 and the controller 8. Multiple resistance strain gauges 74 are attached to the surfaces of the first metal diaphragm 71 and the second metal diaphragm 72, and move along with the first metal diaphragm 71 and the second metal diaphragm 72. 2. The resistance value changes due to the change in the degree of deformation. Since metal diaphragms 71 and 72 are made of different types of metals, and their deformation varies significantly with temperature, and because the deformation of metals under temperature influence is often non-linear, under identical external environmental conditions (i.e., when the temperature and pressure difference between the left and right detection chambers 632 and 633 are consistent), the difference in voltage signals output from the strain gauges 74 attached to metal diaphragms 71 and 72 after discharge through power supply 73 can be used to deduce the difference in deformation of metal diaphragms 71 and 72. This difference can be used to determine the internal temperature of the airflow sensor, and the voltage signal generated by one of the metal diaphragms at this temperature can be compensated for. Figure 8 As shown, the material of metal diaphragm 71 is set to titanium alloy, and the material of metal diaphragm 72 is set to magnesium alloy. At temperature k1, the deformations of the titanium alloy and magnesium alloy are a1 and a2, respectively. The deformation difference between the titanium alloy and magnesium alloy is a3 = a2 - a1. Since the titanium alloy and magnesium alloy are in the same external environment, their deformation difference a3 is only affected by the material. At this time, because the deformation of metals affected by temperature is often non-linear, and the difference in deformation due to temperature is large, a value of deformation difference a3 corresponds only to one external temperature k1. Therefore, when the deformation difference a3... When 3 is determined, the external temperature k1 can be calculated from the deformation difference a3. Then, the controller 8 uses the deformation of one of the metal diaphragms under temperature k1 to compensate for the voltage signal generated by the metal diaphragm, thereby completing the temperature compensation of the airflow sensor. This method can compensate the airflow sensor for temperature without relying on the temperature sensor to detect the temperature, thus avoiding the problem that in the face of high humidity environment, some moisture covers the surface of the temperature sensor probe, which changes its surface thermal conductivity and thus affects the detection accuracy of the airflow sensor.

[0046] As one embodiment of the present invention, refer to Figure 2 , Figure 5and Figure 7 The humidity control component 5 includes a water guide pipe 51, an installation pipe 52, a water absorption expansion member 53, and a compensation connecting rod 54. The water guide pipe 51 passes through multiple throttling members 4 and is connected to the water storage chamber 42. The end of the guide plate 43 is connected to the water guide pipe 51. When droplets enter the water storage chamber 42 through the water inlet trough 41, they will drip onto the guide plate 43 and slide down the guide plate 43 into the water guide pipe 51. The installation pipe 52 is connected to the water guide pipe 51 and is installed between the double-layer filter screens 634. The water absorption expansion member 53 is installed inside the installation pipe 52. The compensation connecting rod 54... One end of rod 54 is slidably installed inside mounting tube 52, and the other end is connected to the outside of metal diaphragm. When a droplet slides down water guide tube 51 into mounting tube 52, it is absorbed by water-absorbing expansion member 53 inside mounting tube 52. Water-absorbing expansion member 53 is filled with water-absorbing expansion material such as treated wood fiber or polyacrylamide hydrogel, whose volume changes linearly with humidity. By controlling the amount and type of water-absorbing expansion material, its volume at a corresponding humidity level is controlled. After the volume of water-absorbing expansion member 53 increases, it will compress the compensating connecting rod 54, causing it to move forward along mounting tube 52. Because one end of the compensation rod 54 is slidably installed inside the mounting tube 52, and the other end is hinged to the middle part of the outer side of the metal diaphragm, when the compensation rod 54 moves, one end of the compensation rod 54 will abut against the water-absorbing expansion member 53 and not move, while the other end will push the metal diaphragm to deform, thereby completing the humidity compensation of the airflow sensor. This invention allows for humidity compensation of the airflow sensor without relying on the humidity sensor's temperature detection, while also removing droplets formed on the surface of the mesh air resistance and the orifice plate, preventing droplets from adsorbing on the surface of the mesh air resistance and the orifice plate and affecting the orifice size. Changes occur, which in turn affect the monitoring accuracy of the airflow sensor. Multiple drainage tubes are installed on the outer periphery of the mounting tube 52. The drainage tubes pass through the mounting tube 52 and connect the water absorption expansion element 53 and the water absorption filter element. Multiple drainage tubes are installed on the outer periphery of the mounting tube 52. There are many tiny capillaries inside the drainage tubes, which can be used for the transfer of moisture. When gas enters the air pressure chamber 63 through the connecting tube 61, the moisture will be absorbed by the water absorption filter element 64 and then enter the water absorption expansion element 53 through the drainage tubes. This method can greatly extend the service life of the water absorption filter element and avoid the need to replace the water absorption filter element frequently.

[0047] As one embodiment of the present invention, refer to Figure 5 and Figure 7A heating element 521 is installed at the contact point between the mounting tube 52 and the water-absorbing expansion member 53. A solenoid valve 522 is installed at the top of the mounting tube 52. The heating element 521 is attached between the mounting tube 52 and the water-absorbing expansion member 53. The heating element 521 contains an electric heating wire and is connected to the power supply 73. The solenoid valve 522 is closed when the airflow sensor is working. After the airflow sensor stops working, the electric heating wire inside the heating element 521 is energized to heat the water-absorbing expansion member 53, accelerating the evaporation of its internal moisture. At the same time, the solenoid valve 522 installed at the top of the mounting tube 52 opens, and the evaporated moisture is discharged along the solenoid valve 522. This solution accelerates the drying of the water-absorbing expansion member 53, allowing it to shrink at a faster rate. It avoids the compensation rod 54 from being pressed against the metal diaphragm for a long time due to excessive humidity, causing it to be in a bent state for a long time, which may lead to metal fatigue and damage the life of the metal diaphragm.

[0048] Working principle: By setting two sets of metal diaphragms of different materials in the output component 7, the difference in the output voltage caused by the different degrees of bending of the two sets of metal diaphragms under the same air pressure difference and temperature can be used to calculate the internal temperature of the airflow sensor. The controller 8 then uses the calculated temperature to compensate one of the signals, thereby achieving precise temperature compensation for the airflow sensor. In addition, by setting a water-absorbing expansion member 53 in the air pressure transmission component 6 and a water-guiding groove 41 in the throttling member 4, the droplets on the surface of the throttling member 4 are adsorbed into the humidity control component 5. At the same time, by controlling the material and number of water-absorbing expansion members 53, the deformation of the expansion member is controlled, thereby achieving precise humidity compensation for the output component 7.

[0049] Specifically: Temperature compensation process: When gas enters the airflow sensor, it enters the diversion chamber 631 through the connecting pipe 61. Through the diversion chamber 631, it enters the left detection chamber 632 and the right detection chamber 633 respectively, making the gas pressure in the left detection chamber 632 and the right detection chamber 633 consistent with the gas pressure in the corresponding connecting pipe 61. The difference between the voltage signals output by the resistance strain gauges 74 attached to the metal diaphragm 71 and the metal diaphragm 72 is obtained by discharging through the power supply 73. The difference in deformation between the metal diaphragm 71 and the metal diaphragm 72 is then deduced. This difference determines the internal temperature of the airflow sensor. The voltage signal generated by one of the metal diaphragms at this temperature is then compensated for, thereby completing the temperature compensation of the airflow sensor. This method can perform temperature compensation of the airflow sensor without relying on the temperature detection of a temperature sensor.

[0050] Water droplet adsorption process on the surface of the throttling device: When droplets condense on the surface of the throttling device 4, they will be adsorbed into the water inlet trough 41 by the hydrophilic material. Since the water inlet trough 41 is connected to the water storage chamber 42, the droplets will enter the water storage chamber 42 along the water inlet trough 41 and drip onto the guide plate 43 installed in the water storage chamber 42. The surface of the guide plate 43 is made of smooth material, and the droplets slide along the guide plate 43 to the end of the guide plate 43.

[0051] Humidity compensation process: When a droplet slides down the water guide tube 51 into the installation tube 52, it will be absorbed by the water-absorbing expansion member 53 inside the installation tube 52. The water-absorbing expansion member 53 is filled with water-absorbing expansion material such as treated wood fiber or polyacrylamide hydrogel, whose volume changes linearly with humidity. After the volume of the water-absorbing expansion member 53 increases, it will squeeze the compensation link 54, causing it to move forward along the installation tube 52. Because one end of the compensation link 54 is slidably installed inside the installation tube 52 and the other end is hinged to the middle part of the outer side of the metal diaphragm, when the compensation link 54 moves, it will push the metal diaphragm to deform, thereby completing the humidity compensation of the airflow sensor.

[0052] Drying process after work: After the airflow sensor stops working, the heating wire inside the heating element 521 is energized to heat the water-absorbing expansion element 53, accelerating the evaporation of its internal moisture. At the same time, the solenoid valve 522 installed at the top of the mounting tube 52 opens, and the evaporated moisture is discharged along the solenoid valve 522. The water-absorbing expansion element 53 continues to dry, and the compensation linkage 54 can contract at a relatively fast rate, and the metal diaphragm returns to its original position.

[0053] The technical features disclosed above are not limited to combinations of the disclosed features with other features. Those skilled in the art may also make other combinations of the technical features according to the purpose of the disclosure in order to achieve the purpose of this disclosure.

Claims

1. A micro-differential pressure airflow sensor with integrated temperature and humidity compensation, comprising a housing (1), an air inlet (2), and an air outlet (3), characterized in that, It also includes a throttling device (4), a humidity control component (5), an air pressure transmission component (6), an output component (7), and a controller (8). The air inlet (2) and the air outlet (3) are respectively connected to the front and rear ends of the housing (1). The throttling device (4) is connected inside the housing (1). The air pressure transmission component (6) is installed at the lower end of the housing (1) and is connected to the front and rear ends of the housing (1). The output component (7) is installed inside the air pressure transmission component (6). The humidity control component (5) is connected inside the throttling device (4) and is connected to the air pressure transmission component (6). When the airflow is detected, the air pressure transmission component (6) guides the air pressure at the front and rear ends to the output component (7). At the same time, the humidity control component (5) guides the droplets on the surface of the throttling device (4) to the air pressure transmission component (6) and pushes the output component (7) to change the output value. The output component (7) generates a voltage signal according to the air pressure difference and outputs the final signal through the controller (8).

2. The micro-differential pressure airflow sensor with integrated temperature and humidity compensation according to claim 1, characterized in that: The pneumatic transmission assembly (6) includes a connecting pipe (61), a connecting valve (62), and a pneumatic chamber (63). The pneumatic chamber (63) is installed at the lower end of the outer shell (1). The two connecting pipes (61) are respectively connected to the outer shell (1) and the front and rear ends of the pneumatic chamber (63). The connecting valve (62) is installed inside the connecting pipe (61). The pneumatic chamber (63) is divided into a diversion chamber (631), a left detection chamber (632), and a right detection chamber (633). The diversion chamber (631) is opened at the front and rear ends of the pneumatic chamber (63) and is connected to the connecting pipe (61). The left detection chamber (632) and the right detection chamber (633) are opened on the left and right sides of the pneumatic chamber (63) and are respectively connected to the diversion chambers (631) at the front and rear ends.

3. The micro-differential pressure airflow sensor with integrated temperature and humidity compensation according to claim 2, characterized in that: A double-layer filter screen (634) is installed inside the diversion cavity (631), and a water-absorbing filter element is installed between the double-layer filter screens (634).

4. The micro-differential pressure airflow sensor with integrated temperature and humidity compensation according to claim 3, characterized in that: The throttling device (4) has multiple water inlet grooves (41) on its surface and a water storage chamber (42) inside it. The water inlet grooves (41) are connected to the water storage chamber (42) and a guide plate (43) is installed in the water storage chamber (42).

5. A micro-differential pressure airflow sensor with integrated temperature and humidity compensation according to claim 4, characterized in that: The throttling device (4) has a boss (44) installed at its front end, and the front end of the boss (44) is a rounded surface.

6. A micro-differential pressure airflow sensor with integrated temperature and humidity compensation according to claim 4, characterized in that: The output component (7) includes a metal diaphragm (71), a metal diaphragm (72), a power supply (73), and resistance strain gauges (74). The metal diaphragm (71) and the metal diaphragm (72) are fixed in the middle of the left detection cavity (632) and the right detection cavity (633), respectively, and are tightly attached to the inner walls of the left detection cavity (632) and the right detection cavity (633). The power supply (73) is installed at the upper end of the air pressure cavity (63). Multiple resistance strain gauges (74) are attached to the surface of the metal diaphragm (71) and the metal diaphragm (72) and are electrically connected to the power supply (73).

7. A micro-differential pressure airflow sensor with integrated temperature and humidity compensation according to claim 6, characterized in that: The humidity control component (5) includes a water guide pipe (51), an installation pipe (52), a water absorption expansion member (53), and a compensation link (54). The water guide pipe (51) is connected to multiple throttling members (4) and is connected to the water storage chamber (42). The end of the guide plate (43) is connected to the water guide pipe (51). The installation pipe (52) is connected to the water guide pipe (51). The installation pipe (52) is installed between the double-layer filter screen (634). The water absorption expansion member (53) is installed inside the installation pipe (52). One end of the compensation link (54) is slidably installed inside the installation pipe (52), and the other end is connected to the outside of the first metal diaphragm (71) and the second metal diaphragm (72).

8. A micro-differential pressure airflow sensor with integrated temperature and humidity compensation according to claim 7, characterized in that: A heating element (521) is installed at the contact portion between the mounting tube (52) and the water-absorbing expansion member (53), and a solenoid valve (522) is installed at the top of the mounting tube (52).

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