Micro differential pressure type airflow sensor integrated with temperature and humidity compensation

Abstract

The invention relates to the technical field of airflow sensors, in particular to an integrated temperature and humidity compensation micro differential pressure type airflow sensor which comprises a humidity control assembly, an air pressure transmission assembly, an output assembly and a regulator, the air pressure transmission assembly is installed at the lower end of a shell, the output assembly is installed in the air pressure transmission assembly, and the lower end humidity control assembly is connected into a throttling element; when air flow is detected, the air pressure transmission assembly guides air pressure at the front end and air pressure at the rear end into the output assembly, and meanwhile the humidity control assembly guides liquid drops on the surface of the throttling element into the air pressure transmission assembly and pushes the output assembly to change an output value. And the output assembly generates a voltage signal according to the air pressure difference and outputs a final signal through the regulator, so that the problems that in a low-temperature and high-humidity environment, high-humidity gas can form liquid drops on the surfaces of the net-shaped air resistor and the pore plate to influence the detection precision, and when the liquid drops are attached to the surface of the temperature probe, the thermal conductivity of a surface material of the temperature probe can be changed are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of airflow sensors, and in particular to a micro-pressure differential airflow sensor with integrated temperature and humidity compensation. Background Art

[0002] Airflow sensor is a type of intelligent sensor. With its high precision, real-time monitoring and strong environmental adaptability, it is widely used in core fields such as medical, industrial, automotive, and environmental monitoring. Its working principle is that when passing through a throttling device (such as a mesh air resistance, 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 move toward the low-pressure side, thereby causing 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 the temperature rises, the gas density decreases, and the pressure difference value output by the differential pressure airflow sensor decreases at the same flow rate. The change in temperature will also cause the deformation of the diaphragm to change, which will directly affect the degree of bending of the diaphragm, resulting in a further decrease in the detection accuracy of the airflow sensor. In the prior art, a temperature sensor and a humidity sensor are set at both ends of the throttling member to detect the temperature and humidity in the air, and an algorithm is used to compensate the detection results of the airflow sensor, thereby correcting the voltage signal output by the airflow sensor and improving the output accuracy of the airflow sensor.

[0004] However, when used to detect exhaust volume in high humidity environments, such as using airflow sensors in ventilators to detect patient breathing conditions, the humidity is high when the patient breathes. When the external ambient temperature is low, the internal temperature of the airflow sensor is lower than the dew point. When high-humidity gas enters the airflow sensor, long-term use may form droplets on the surface of the mesh air resistance and the orifice plate, changing the airflow direction inside the airflow sensor and the aperture size of the airflow, thereby affecting the detection accuracy of the airflow sensor. Since the accumulation of droplets on the surface of the orifice plate is a continuous and irregular process, it cannot be accurately compensated by simply using an algorithm. When droplets adhere to the surface of the temperature probe, they will change the thermal conductivity of the surface material of the temperature probe, affecting its detection accuracy, resulting in inaccurate algorithm compensation.

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

[0006] The present invention provides a micro-pressure differential airflow sensor with integrated temperature and humidity compensation. The air pressure at both ends of the airflow sensor is transmitted to the output component by utilizing an air pressure transmission component. At the same time, a humidity control component is used to prevent droplets from accumulating on a throttling component and to perform humidity compensation on the output component. Two groups of different metal diaphragms are provided in the output component, and the temperature inside the airflow sensor is measured and calculated by comparing their different bending degrees at the same temperature. The temperature is then compensated and a final signal is outputted by a controller. The above-mentioned method solves the problem that in a low-temperature and high-humidity environment, high-humidity gas will form droplets on the surface of a mesh air resistance and an orifice plate, affecting detection accuracy, and that when droplets adhere to the surface of a temperature probe, the thermal conductivity of the surface material of the temperature probe will be changed.

[0007] A micro-pressure differential airflow sensor with integrated temperature and humidity compensation includes a shell, an air inlet, an air outlet, a throttle, a humidity control component, an air pressure transmission component, an output component and a regulator. The air inlet and the air outlet are respectively connected to the front and rear ends of the shell, the throttle is connected inside the shell, the air pressure transmission component is installed at the lower end of the shell and is connected to the front and rear ends of the shell, the output component is installed inside the air pressure transmission component, the humidity control component at the lower end is connected to the inside of the throttle and is connected to the inside of the air pressure transmission component, when the airflow is detected, the air pressure transmission component respectively guides the air pressure at the front and rear ends to the output component, and at the same time, the humidity control component guides the droplets on the surface of the throttle to the air pressure transmission component and pushes the output component to change the output value, and the output component generates a voltage signal according to the air pressure difference and outputs the final signal through the regulator.

[0008] Preferably, the air pressure transmission component includes a connecting pipe, a connecting valve and an air pressure chamber. The air pressure chamber is installed at the lower end of the shell, and the connecting valve is installed in the connecting pipe. The two connecting pipes respectively connect the shell with the front and rear ends of the air pressure chamber. The air pressure chamber is divided into a diversion chamber, a left detection chamber and a right detection chamber. The diversion chamber is opened at the front and rear ends of the air pressure chamber and is connected to the connecting pipe. The left detection chamber and the right detection chamber are opened on the left and right sides of the air pressure 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, a plurality of water diversion grooves are provided on the surface of the throttling member, a water storage cavity is provided inside the throttling member, the water diversion grooves are connected to the water storage cavity, and a guide plate is installed in the water storage cavity.

[0011] Preferably, a boss is installed at the front end of the throttling member, and the front end of the boss is a rounded surface.

[0012] Preferably, the output component includes metal diaphragm 1, metal diaphragm 2, a power supply and a resistance strain gauge. The metal diaphragm 1 and metal diaphragm 2 are respectively fixed in the middle position of the left detection cavity and the right detection cavity, and are tightly fitted to the inner walls of the left detection cavity and the right detection cavity. The power supply is installed at the upper end of the air pressure cavity, and multiple resistance strain gauges are fitted on the surfaces of metal diaphragm 1 and metal diaphragm 2 and are electrically connected to the power supply.

[0013] Preferably, the humidity control component includes a water pipe, a mounting pipe, a water absorption expansion piece and a compensation connecting rod. The water pipe connects multiple throttling parts and is connected to the water storage chamber. The mounting pipe is installed between the double-layer filter screens, the water absorption expansion piece is installed in the mounting pipe, and one end of the compensation connecting rod is slidably installed in the mounting pipe, and the other end is connected to the outside of the metal diaphragm.

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

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

[0016] 1. Compared with traditional airflow sensors that monitor the internal temperature and humidity of the airflow sensor through temperature sensors and humidity sensors and use algorithms for compensation, this solution sets up an air pressure transmission component and an output component to measure the internal temperature of the airflow sensor by comparing two sets of metal diaphragms. This solves the problem that when droplets adhere to the surface of the temperature probe, the thermal conductivity of the temperature probe surface material will change, thereby affecting the detection accuracy. At the same time, by setting up a humidity control component to remove droplets formed on the surface of the mesh air resistance and orifice plate and compensate for the output component, it solves the problem that high-humidity gas will form droplets on the surface of the mesh air resistance and orifice plate in a low-temperature and high-humidity environment, thereby affecting the detection accuracy.

[0017] 2. The present invention provides an air pressure transmission component and an output component, and provides two groups of metal diaphragms made of different materials in the output component. The temperature inside the airflow sensor is calculated based on the difference in output voltage caused by the different degrees of bending of the two groups of metal diaphragms under the same air pressure difference and the same temperature. The controller then compensates one group of signals using the measured temperature, thereby achieving the effect of accurately compensating the temperature of the airflow sensor. This solution can avoid the problem of droplets adhering to the surface of the temperature probe due to excessive humidity, which leads to changes in heat transfer rate and inaccurate measurements, thereby improving the accuracy of the airflow sensor.

[0018] 3. The present invention sets a humidity control component, sets a water-absorbing expansion member in the air pressure transmission component and sets a water diversion groove in the throttling member, absorbs the liquid droplets on the surface of the throttling member into the humidity control component, and controls the deformation of the water-absorbing expansion member by controlling the material and quantity of the water-absorbing expansion member in the water-absorbing expansion member, thereby accurately compensating the humidity of the output component. This solution can prevent liquid droplets from adhering to the surface of the throttling member, thereby reducing the aperture of the throttling member and affecting the accuracy of the airflow sensor. At the same time, by connecting the water-absorbing expansion member with the water-absorbing filter element in the double-layer filter screen, the water vapor inside the air pressure transmission component can be filtered out, thereby reducing water vapor corrosion when it contacts the metal diaphragm. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

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

[0021] Figure 1 It 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 It is a schematic axial side view of a cross-sectional view of a throttling member of the present invention;

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

[0025] Figure 5 This invention Figure 4 Axial schematic diagram of the section along section AA;

[0026] Figure 6 This invention Figure 4 Axial schematic diagram of the cross-section of the middle BB section;

[0027] Figure 7 This invention Figure 5 Enlarged view of part C in the middle;

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

[0029] In the picture:

[0030] 1. Shell;

[0031] 2. Air inlet;

[0032] 3. Air outlet;

[0033] 4. Throttle; 41. Water diversion trough; 42. Water storage chamber; 43. Guide plate; 44. Boss;

[0034] 5. Humidity control assembly; 51. Water guide pipe; 52. Mounting pipe; 521. Heating plate; 522. Solenoid valve; 53. Water absorption expansion element;

[0035] 54. Compensating connecting rod;

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

[0037] 7. Output component; 71. Metal diaphragm 1; 72. Metal diaphragm 2; 73. Power supply; 74. Resistance strain gauge;

[0038] 8. Controller. DETAILED DESCRIPTION

[0039] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0040] As an embodiment of the present invention, refer to Figures 1 to 8, a micro-pressure differential airflow sensor with integrated temperature and humidity compensation, including a shell 1, an air inlet 2, an air outlet 3, a throttle 4, a humidity control component 5, an air pressure transmission component 6, an output component 7 and a regulator 8. The air inlet 2 and the air outlet 3 are respectively connected to the front and rear ends of the shell 1 and are communicated with the equipment outside that needs to detect the air flow. The throttle 4 is fixedly installed inside the shell 1. When there is air flow, the throttle 4 reduces the aperture of the gas flow, and its flow rate relative to the air inlet 2 will become faster, thereby forming an air pressure difference at the air inlet 2 and the air outlet 3. The air pressure transmission component 6 is installed at the lower end of the shell 1 and is connected to the front and rear ends of the shell 1. The gas at the air inlet 2 and the air outlet 3 is transmitted to the output component 7 through the air pressure transmission component 6. The gas pressure directly acts on the output component 7. The output component 7 is installed Inside the air pressure transmission component 6, the output component 7 will produce a certain deformation due to the difference in air pressure on both sides, thereby generating a voltage signal. The humidity control component 5 is connected to the inside of the throttling member 4, and is used to absorb the water droplets exposed on the surface of the throttling member 4. At the same time, the humidity control component 5 is connected to the inside of the air pressure transmission component 6 to perform humidity compensation on the output component 7. When detecting the airflow, the air pressure transmission component 6 transmits the air pressure at the front and rear ends of the airflow sensor to the output component 7 respectively. At the same time, the humidity control component 5 absorbs the droplets on the surface of the throttling member 4 and transmits them to the air pressure transmission component 6, while pushing the output component 7 to change the deformation of the output component 7 and then perform humidity compensation on it. The output component 7 produces deformation according to the air pressure difference at both ends and outputs a voltage signal after humidity compensation. The voltage signal is temperature compensated through the regulator 8 and then outputs the final signal.

[0041] As an embodiment of the present invention, refer to Figure 4 、 Figure 6, the 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 shell 1. The air pressure chamber 63 is a sealed box for installing the output component 7 and generating an air pressure difference on both sides of the output component 7. The two connecting pipes 61 respectively connect the shell 1 with the front and rear ends of the air pressure chamber 63. The connection points of the two connecting pipes 61 and the shell 1 are located at the front and rear ends of the throttle member 4, which are respectively responsible for transmitting the air pressure of 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 air flow sensor is working, the connecting valve 62 is opened. When the air flow sensor is not working, the connecting valve 62 is closed to prevent external water vapor 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 632 and the right detection chamber 633, the diverter chamber 631 is opened at the front and rear ends of the air pressure 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 air pressure chamber 63, and are respectively connected to the diverter chamber 631 at the front and rear ends. The diverter chamber 631 is opened at the front and rear ends of the air pressure chamber 63. When the gas enters the interior of the air flow sensor, it will enter the diverter chamber 631 through the connecting pipe 61, and enter the left detection chamber 632 and the right detection chamber 633 through the diverter chamber 631 respectively, and make the left detection chamber 632 and the right detection chamber 633 consistent with the air pressure of the corresponding connecting pipe 61. Through this method, two detection chambers with exactly the same temperature and 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 an embodiment of the present invention, refer to Figure 6 A double-layer filter 634 is installed in the diversion chamber 631, and a water-absorbing filter element is installed between the double-layer filter 634. The connection point between the connecting pipe 61 and the diversion chamber 631 is located below the double-layer filter 634, and the connection position 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 the gas passes through the double-layer filter 634 and enters the left detection chamber 632 and the right detection chamber 633, the moisture will be removed by the water-absorbing filter element to prevent high-humidity air from entering the detection chamber and corroding the internal components of the output component 7, resulting in a decrease in its accuracy.

[0043] As an embodiment of the present invention, refer to Figure 2 、 Figure 3The throttling member 4 has a plurality of water diversion grooves 41 on its surface, a water storage chamber 42 is provided inside the throttling member 4, the water diversion grooves 41 are connected to the water storage chamber 42, a guide plate 43 is installed in the water storage chamber 42, the surface of the water diversion grooves 41 is made of a hydrophilic material, the water diversion grooves 41 are provided on the surface of the throttling member 4, and the surface of the throttling member 4 is provided with an inclined surface with the water diversion grooves 41 as the center of the circle. When droplets condense on the surface of the throttling member 4, they will be adsorbed by the hydrophilic material into the water diversion grooves 41. Since the water diversion grooves 41 are connected to the The liquid droplets will flow into the water storage chamber 42 along the water inlet groove 41, and 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, and the liquid droplets will 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 member 4, it will be adsorbed by the water inlet groove 41 and enter the water storage chamber 42, thereby preventing the droplets from staying on the throttling member 4, affecting the airflow direction inside the airflow sensor and changing the aperture size of the throttling member 4.

[0044] As an embodiment of the present invention, refer to Figure 3 A boss 44 is installed at the front end of the throttling member 4, and the front end of the boss 44 is a rounded surface. When the airflow passes through the boss 44 at the front end of the throttling member 4, since the front end of the boss 44 is a rounded surface, the airflow will change its movement direction along the rounded surface of the front end of the boss 44, and then adhere to the side surfaces of the throttling member 4 on the upper and lower sides of the throttling member 4, so that it will push the droplets on the surface of the throttling member 4 on the upper and lower sides into the above-mentioned water guide groove 41.

[0045] As an embodiment of the present invention, refer to Figure 5 、 Figure 6 and Figure 7The output component 7 includes a metal diaphragm 1 71, a metal diaphragm 2 72, a power supply 73 and a resistance strain gauge 74. The metal diaphragm 1 71 and the metal diaphragm 2 72 are fixed in the middle of the left detection cavity 632 and the right detection cavity 633 respectively. The metal diaphragm 1 71 and the metal diaphragm 2 72 are made of different types of metals, and their deformation amounts are greatly affected by temperature. The metal diaphragm 1 71 and the metal diaphragm 2 72 are tightly fitted to the inner walls of the left detection cavity 632 and the right detection cavity 633, so that the gas at both ends cannot pass through the gap between the metal diaphragm 1 71 and the metal diaphragm 2 72. The power supply 73 is installed at the upper end of the air pressure cavity 63 and is responsible for supplying power to the resistance strain gauge 74 and the regulator 8. Multiple resistance strain gauges 74 are attached to the surfaces of the metal diaphragm 1 71 and the metal diaphragm 2 72 and move with the metal diaphragm 1 71 and the metal diaphragm 2 72. 2. The resistance value changes with the change in deformation degree. Since the metal diaphragm 1 71 and the metal diaphragm 2 72 are made of different types of metals, and their deformation variables are greatly affected by temperature, and since the deformation variables of metals affected by temperature often show nonlinear changes, under the same external environment, that is, when the temperature in the left detection cavity 632 and the right detection cavity 633 are consistent and the pressure difference at both ends is consistent, the difference in the voltage signals output by the resistance strain gauge 74 attached to the metal diaphragm 1 71 and the metal diaphragm 2 72 through the discharge of the power supply 73 can be used to infer the difference in the deformation variables of the metal diaphragm 1 71 and the metal diaphragm 2 72. The internal temperature of the airflow sensor can be determined by this difference, and the voltage signal generated by one of the metal diaphragms at this temperature can be compensated. Figure 8 As shown, the material of the metal diaphragm 1 71 is set to titanium alloy, and the material of the metal diaphragm 2 72 is set to magnesium alloy. At the temperature k1, the deformation variables of the titanium alloy and the magnesium alloy are a1 and a2 respectively, and the deformation difference between the titanium alloy and the magnesium alloy is a3 = a2 - a1. Since the titanium alloy and the magnesium alloy are in the same external environment, the deformation difference a3 is only affected by the material. At this time, since the deformation variable of the metal affected by temperature often changes nonlinearly, and the difference in its deformation variable affected by temperature is large, the value of a deformation difference a3 only corresponds to one external temperature k1, so when the deformation difference a3 is less than 0.05, the deformation difference a3 is less than 0.05. 3, the external temperature k1 can be calculated by the deformation difference a3, and then the controller 8 uses the deformation amount generated by one of the metal diaphragms at the temperature k1 to compensate the voltage signal generated by the metal diaphragm, thereby completing the temperature compensation of the airflow sensor. This method can perform temperature compensation on the airflow sensor without relying on the temperature detection of the temperature sensor, thereby avoiding the problem that in a high humidity environment, part of the moisture covers the temperature probe on the surface of the temperature sensor, causing the surface thermal conductivity to change, thereby affecting the detection accuracy of the airflow sensor.

[0046] As an embodiment of the present invention, refer to Figure 2 、 Figure 5and Figure 7 The humidity control component 5 includes a water pipe 51, a mounting pipe 52, a water absorption expansion piece 53 and a compensation connecting rod 54. The water pipe 51 passes through multiple throttling parts 4. The interior of the water pipe 51 is connected to the water storage chamber 42, and the end of the guide plate 43 is connected to the water pipe 51. When the droplets enter the water storage chamber 42 through the water guide groove 41, they will drip onto the guide plate 43 and slide down the guide plate 43 into the water pipe 51. The mounting pipe 52 is connected to the water pipe 51 and is installed between the double-layer filter screen 634. The water absorption expansion piece 53 is installed in the mounting pipe 52. The compensation connecting rod One end of the rod 54 is slidably installed in the installation tube 52, and the other end is connected to the outside of the metal diaphragm. When the droplets slide down the water guide pipe 51 into the installation tube 52, they will be absorbed by the water-absorbing expansion member 53 in the installation tube 52. The water-absorbing expansion member 53 is filled with water-absorbing expansion materials such as treated wood fiber or polyacrylamide hydrogel, whose volume changes linearly with humidity. By controlling the amount and material of the water-absorbing expansion material, its volume at the corresponding humidity is controlled. After the volume of the water-absorbing expansion member 53 increases, it will squeeze the compensating connecting rod 54 to make it move forward along the installation tube 52. Because one end of the compensation link 54 is slidably mounted in the mounting tube 52, and the other end is hinged to the middle portion of the outer side of the metal diaphragm, when the compensation link 54 moves, one end of the compensation link 54 will resist the water-absorbing expansion member 53 and will not move, while the other end will push the metal diaphragm to deform it, thereby completing the humidity compensation of the airflow sensor. The present invention can compensate the airflow sensor for humidity without relying on the humidity sensor's temperature detection, and at the same time removes the droplets formed on the surface of the mesh air resistance and the orifice plate, avoiding the size of the pores due to the adsorption of droplets on the surface of the mesh air resistance and the orifice plate. Changes occur, thereby affecting the monitoring accuracy of the airflow sensor. A plurality of drainage tubes are installed on the periphery of the mounting tube 52. The drainage tubes pass through the mounting tube 52 and are connected to the water absorption expansion member 53 and the water absorption filter element. A plurality of drainage tubes are installed on the periphery of the mounting tube 52. There are many tiny capillaries inside the drainage tubes, which can be used for the transfer of water. When the gas enters the air pressure chamber 63 through the connecting tube 61, the water will be absorbed by the water absorption filter element 64, and then enter the water absorption expansion member 53 through the drainage tube. This method can greatly extend the service life of the water absorption filter element and avoid the need to frequently replace the water absorption filter element.

[0047] As an embodiment of the present invention, refer to Figure 5 and Figure 7A heating plate 521 is installed at the contact part of the mounting tube 52 and the water absorption expansion member 53, and an electromagnetic valve 522 is installed at the top of the mounting tube 52. The heating plate 521 is fitted between the mounting tube 52 and the water absorption expansion member 53. There is a heating wire inside the heating plate 521 and it is connected to the power supply 73. A electromagnetic valve 522 is installed at the top of the mounting tube 52. The electromagnetic valve 522 is in a closed state when the airflow sensor is working. After the airflow sensor finishes working, the heating wire inside the heating plate 521 is energized to heat the water absorption expansion member 53 and accelerate the evaporation of water inside it. At the same time, the electromagnetic valve 522 installed at the top of the mounting tube 52 is opened, and the evaporated water is discharged along the electromagnetic valve 522. This solution accelerates the drying of the water absorption expansion member 53 so that it can shrink at a faster rate, thereby avoiding the compensation connecting rod 54 from pressing 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 cause metal fatigue after a long time and damage the life of the metal diaphragm.

[0048] Working principle: By setting two groups of metal diaphragms made of different materials in the output component 7, the difference in output voltage is different due to the different bending degrees of the two groups of metal diaphragms under the same air pressure difference and the same temperature, and then the temperature inside the airflow sensor is calculated, and then one group of signals is compensated by the measured temperature through the regulator 8, so as to achieve the effect of accurate compensation of the airflow sensor temperature, and by setting a water-absorbing expansion member 53 in the air pressure transmission component 6 and a water guide groove 41 in the throttling member 4, the droplets on the surface of the throttling member 4 are adsorbed into the inside of the humidity control component 5, and the deformation of the water-absorbing expansion member is controlled by controlling the material and quantity of the water-absorbing expansion member 53, thereby accurately compensating the humidity of the output component 7.

[0049] Specifically: Temperature compensation process: When gas enters the interior of the airflow sensor, it will enter the diversion chamber 631 through the connecting tube 61, and enter the left detection chamber 632 and the right detection chamber 633 through the diversion chamber 631 respectively, and make the left detection chamber 632 and the right detection chamber 633 consistent with the air pressure of the corresponding connecting tube 61. The power supply 73 discharges through the difference in voltage signals output by the resistance strain gauge 74 attached to the metal diaphragm 1 71 and the metal diaphragm 2 72, and the difference in the deformation of the metal diaphragm 1 71 and the metal diaphragm 2 72 is inferred. The internal temperature of the airflow sensor can be determined by this difference, and then the voltage signal generated by one of the metal diaphragms at this temperature is compensated for by the deformation of this metal diaphragm, thereby completing the temperature compensation of the airflow sensor. In this way, the airflow sensor can be temperature compensated without relying on the temperature sensor to detect the temperature.

[0050] The process of water droplet adsorption on the surface of the throttling member: When droplets condense on the surface of the throttling member 4, they will be adsorbed into the water diversion groove 41 by the hydrophilic material. Since the water diversion groove 41 is connected to the water storage chamber 42, the droplets will enter the water storage chamber 42 along the water diversion groove 41, and at the same time 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, and the droplets slide along the guide plate 43 to the end of the guide plate 43.

[0051] Humidity compensation process: When the droplets slide down the water pipe 51 into the mounting tube 52, they will be absorbed by the water-absorbing expansion member 53 inside the mounting tube 52. The water-absorbing expansion member 53 is filled with water-absorbing expansion materials such as treated wood fibers 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 to move it forward along the mounting tube 52. Because one end of the compensation link 54 is slidably installed in 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 link 54 moves, it will push the metal diaphragm to deform it, thereby completing the humidity compensation of the airflow sensor.

[0052] Drying process after work: After the airflow sensor finishes working, the heating wire inside the heating plate 521 is energized to heat the water absorption expansion member 53, accelerating the evaporation of water inside it. At the same time, the solenoid valve 522 installed at the top of the mounting tube 52 is opened, and the evaporated water is discharged along the solenoid valve 522. The water absorption expansion member 53 is continuously dried, and the compensation connecting rod 54 can shrink at a faster rate, and the metal diaphragm returns to its original position.

[0053] The technical features disclosed above are not limited to the combination with other features disclosed. Those skilled in the art can also make other combinations between the technical features according to the purpose of disclosure 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: The air inlet (2) and the air outlet (3) are respectively connected to the front and rear ends of the housing (1); the throttle (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 throttle (4) and is connected to the inside of the air pressure transmission component (6); when the air flow 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 throttle (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 regulator (8).

2. The micro-differential pressure airflow sensor with integrated temperature and humidity compensation according to claim 1, characterized in that: The 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 housing (1). The two connecting pipes (61) respectively connect the housing (1) and the front and rear ends of the air pressure chamber (63). The connecting valve (62) is installed in the connecting pipe (61). The air pressure 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 air pressure 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 air pressure chamber (63) and are respectively connected to the diversion chamber (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 in the diversion cavity (631), and a water-absorbing filter element is installed between the double-layer filter screen (634).

4. The micro-differential pressure airflow sensor with integrated temperature and humidity compensation according to claim 2, characterized in that: A plurality of water diversion grooves (41) are provided on the surface of the throttling member (4), a water storage chamber (42) is provided inside the throttling member (4), the water diversion grooves (41) are connected to the water storage chamber (42), and a guide plate (43) is installed in the water storage chamber (42).

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

6. The micro-differential pressure airflow sensor with integrated temperature and humidity compensation according to claim 2, characterized in that: The output component (7) includes a metal diaphragm 1 (71), a metal diaphragm 2 (72), a power supply (73) and a resistance strain gauge (74). The metal diaphragm 1 (71) and the metal diaphragm 2 (72) are respectively fixed in the middle position of the left detection cavity (632) and the right detection cavity (633), and are tightly fitted with 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). A plurality of resistance strain gauges (74) are fitted on the surfaces of the metal diaphragm 1 (71) and the metal diaphragm 2 (72), and are electrically connected to the power supply (73).

7. The 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), a mounting pipe (52), a water absorption expansion member (53) and a compensation connecting rod (54). The water guide pipe (51) is connected to multiple throttling members (4) and is connected to the water storage chamber (42). The mounting pipe (52) is installed between the double-layer filter screens (634). The water absorption expansion member (53) is installed in the mounting pipe (52). One end of the compensation connecting rod (54) is slidably installed in the mounting pipe (52), and the other end is connected to the outside of the metal diaphragm 1 (71) and the metal diaphragm 2 (72).

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

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