A pressure differential air volume measurement device and method

Abstract

The present invention discloses a pressure-differential air volume measurement device, which includes a measurement base and a wind hood connected by a cover body connecting seat. The wind hood faces the air outlet of the air volume to be measured. The measurement base is provided with a concentric circle bracket, and the concentric circle bracket is composed of a vertically arranged central connecting pipe and multiple circles of ventilation pipes coiled on the central connecting pipe. Each of the ventilation pipes is provided with an air hole. One end of the ventilation pipe is sealed, and the other end is connected to one end of the pipe in the central connecting pipe. The other end of the pipe is connected to the measurement unit outside the measurement base. The present invention adopts a bellows with a memory function as the cover body connecting seat through design. The length of the connecting seat and the relative angle with the cover body can be adjusted, changing the angle between the cover body base and the wind direction. At the same time, by adjusting the length of the connecting seat, the flow field state of the base and the connecting seat section is optimized, thereby improving the accuracy of average wind speed measurement.

Description

Technical Field

[0001] The present invention relates to the technical field of gas flow detection, and in particular to a pressure differential type high-precision air volume hood and a signal processing method thereof. Background Art

[0002] The air flow hood is primarily used to measure air volume, funneling wind to the wind pressure sensor on the base section. It consists of three main components: the hood body, the base, and the PDA. The wind pressure sensor is located within the cylindrical base section, while the PDA is also located outside the base. The wind pressure sensor measures the pressure differential, calculates the wind speed from this differential, and then calculates the air volume based on the base dimensions. The wind speed, temperature, and air volume data are then displayed directly on the PDA screen. Continuous real-time recording of various parameters can be set to facilitate later data export and analysis.

[0003] At present, the air volume of the air outlet is generally measured using an air volume hood. However, the wind direction of the existing louver air outlet cannot ensure that the air flow is blowing directly towards the wind speed uniformizer. The throttling resistance of the air volume hood cover and the measuring part to the air outlet will also cause the air volume to decrease, affecting the test accuracy. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to realize a directionally variable and telescopic high-precision air volume hood capable of measuring the air supply volume of a variable-direction air outlet.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a pressure differential air volume measuring device, the device is provided with a measuring base and a wind cover connected by a cover body connecting seat, the wind cover faces the air outlet of the air volume to be measured, and a concentric circle bracket is provided in the measuring base, the concentric circle bracket is composed of a vertically arranged central connecting pipe and multiple circles of ventilation pipes coiled on the central connecting pipe, each of the ventilation pipes is provided with an air hole, one end of the ventilation pipe is sealed, and the other end is connected to one end of the pipe in the central connecting pipe, and the other end of the pipe is connected to the measuring unit outside the measuring base.

[0006] The ventilation pipe is provided with four circles, and each of the ventilation pipes is separated into a windward pipe and a leeward pipe by a partition. The pipe includes four full-pressure cavity pipes and four static pressure cavity pipes. Each of the windward pipes is provided with at least one air hole, one end of the windward pipe is sealed, and the other end is connected to a full-pressure cavity pipe. Each of the leeward pipes is provided with at least one air hole, one end of the leeward pipe is sealed, and the other end is connected to a static pressure cavity pipe.

[0007] An electric valve is provided in each of the total pressure cavity tube and the static pressure cavity tube.

[0008] The measuring unit is provided with a wind pressure sensor connected to each full-pressure cavity tube and static pressure cavity tube. Each wind pressure sensor is connected to and outputs a sensing signal to the wind speed transmission module. The wind speed transmission module outputs the sensing signal to the main controller. The main controller is connected to the signal output module. The signal output module is connected to and outputs the signal to the electric valve, communication module and display screen. The measuring unit contains a power supply module that supplies power to all components.

[0009] A temperature and humidity sensor is fixed to the inner wall of the measuring base, and the temperature and humidity sensor is connected to the measuring unit through a wiring harness. A wiring harness tube for the wiring harness to pass through is provided at the center of the central connecting tube. The four full-pressure cavity tubes and the four static pressure cavity tubes are arranged around the wiring harness tube. A fixed shaft is provided at the top end of the central connecting tube, and is fixed to the inner wall of the measuring base through the fixed shaft.

[0010] The cover connecting seat is a bellows, and a bracket for installation and fixation is fixed on the outer surface of the measuring base.

[0011] A grid plate plug-in arranged in a grid shape is fixed in the wind hood. The grid plate plug-in is a strip-shaped plate that intersects perpendicularly with each other and is arranged in the wind hood to form a plurality of independent air ducts.

[0012] A pressure differential air volume measurement method comprises the following steps:

[0013] Step 1: Collect data from each wind pressure sensor;

[0014] Step 2: Calculate the measured air volume value based on the data;

[0015] Step 3: Display and output the measured air volume value;

[0016] Step 4: Determine whether the measurement is finished. If so, it ends. If not, return to step 1.

[0017] The calculation method of step 2 is as follows: the measured air volume value is Q;

[0018] Q=S(aV1+bV2+cV3+dV4);

[0019] Where S is the cross-sectional area of ​​the base section where the wind pressure sensor is installed;

[0020] V1~V4 are the wind speed values ​​measured in four different ventilation pipes;

[0021] a, b, c, and d are the corresponding wind speed coefficients respectively.

[0022] The measured air volume value Q is compensated by the acquired temperature value and humidity value to obtain the measured air volume of the air outlet.

[0023] The present invention forms a structure-variable air volume hood by providing a measuring bracket with a variable measuring cross-sectional angle and adopting a bellows with a memory function as a retractable base. The measurement mode is selected by a button on the micromanometer, and the effect of a hardware filter is achieved by a software algorithm. The filtering parameters can be adjusted at any time to obtain more stable and effective data, which not only ensures the real-time follow-up of the measurement data but also improves the stability of the measurement, thereby improving the overall measurement accuracy of the air volume hood for the air supply volume. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The following is a brief description of the contents and marks in each figure in the specification of the present invention:

[0025] Figure 1 、 2 3 is a schematic diagram of the air volume hood structure;

[0026] Figure 4 It is a schematic diagram of the concentric circle bracket structure;

[0027] Figure 5 This is a schematic diagram of the cross-sectional structure of one of the ventilation pipes of the concentric circle bracket;

[0028] Figure 6 It is a schematic diagram of the central connecting pipe structure in the concentric circle bracket;

[0029] Figure 7 This is the block diagram of the wind speed measurement system;

[0030] Figure 8 This is a flow chart of the wind speed measurement method;

[0031] The marks in the above figure are: 1. Measuring base; 2. Concentric circle bracket; 3. Central connecting pipe; 4. Measuring unit; 5. Bracket; 6. Cover body connecting seat; 7. Wind hood; 8. Fixed axis; 9. Ventilation pipe; 10. Partition; 11. Air hole; 12. Wire harness tube; 13. Full pressure cavity tube; 14. Static pressure cavity tube. DETAILED DESCRIPTION

[0032] Below, with reference to the accompanying drawings, through the description of the embodiments, the specific implementation methods of the present invention, such as the shape, structure, relative positions and connection relationships of the various components involved, the functions and working principles of the various components, the manufacturing process and operating methods, etc., are further explained in detail to help those skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention.

[0033] like Figure 1-3As shown, the differential pressure air volume measurement device consists of three main components: a measuring base 1, a housing connector 6, and a wind hood 7. The housing connector 6 connects the measuring base 1 and the wind hood 7. It uses a bellows with a memory function, allowing the connector length and relative angle with the housing to be adjusted, changing the angle between the housing base and the wind direction. Adjusting the connector length optimizes the flow field between the base and connector, improving the accuracy of average wind speed measurements. Adjusting the connector length also changes the relative position of the wind pressure sensor, changing the mode of measuring a single average wind speed surface, increasing the amount of raw wind pressure data, and reducing measurement errors.

[0034] The wind hood 7 faces the outlet of the air volume to be measured. The wind hood 7 is generally in the shape of a trumpet, and its internal dimensions gradually increase from the hood body connection seat 6 toward the air inlet. A grid-shaped grid plate plug-in is fixed in the wind hood 7. The grid plate plug-in is a strip-shaped plate that intersects perpendicularly and is arranged in the wind hood 7 to form multiple independent air ducts. For example, 9 groups of 18 detachable grid plate plug-ins that intersect perpendicularly are provided. The length of the lower end of the grid plate is less than the diameter of the measuring section, the length of the upper end of the grid plate is less than the length of the hood opening, and the height of the grid plate is less than the length of the hood body. The grid plate can effectively reduce the impact of turbulent airflow on the air volume hood tested by pressure difference, so that the measured airflow forms a laminar flow state within the hood body through the measuring cross section, ensuring measurement accuracy, and making the wind volume hood of the present invention suitable for measuring the air volume at the tuyere of rotating airflow.

[0035] To ensure air tightness, rubber gaskets are provided at the connection parts between the cover body connecting seat 6 and the measuring base 1 and the wind cover 7. A bracket 5 for installation and fixation is fixed on the outer surface of the measuring base 1. The shape of the bracket 5 can be designed as needed to facilitate fixing it in the measuring position.

[0036] The measuring base 1 is the core of the entire device. A concentric circle bracket 52 is fixed inside the measuring base 1. Each layer of the concentric circle bracket 52 is a measuring point. Through the independent annular average velocity tube sensor, the multi-point average wind speed calculation method is changed. The average wind speed at the position of the circular ring with different radius is measured separately, and the cross-sectional average wind speed is calculated using the data curve fitting method. The four-ring measurement data is calibrated with a coefficient to display the measured wind volume value.

[0037] The center of the concentric circle bracket 52 is a central connecting tube 3, which serves as the main body core and is used to connect and fix the entire concentric circle bracket 52. One end of the central connecting tube 3 is fixed to the inner wall of the measuring base 1 through a fixed shaft 8. There is a damping force between the fixed shaft 8 and the inner wall of the measuring base 1, and it can hover at a desired angle. In this way, the angle between the concentric circle bracket 52 and the gas flow direction can be adjusted, thereby changing the angle between the airflow and the measuring section, which is suitable for measuring the air volume at the air outlet that is not directly facing the air outlet in the cover.

[0038] Multiple circles of ventilation pipes 9 are fixed on the central connecting pipe 3 in a concentric circle structure. The number of circles of the ventilation pipes 9 can be set as needed, for example, four are set. Each of the ventilation pipes 9 is provided with an air hole 11. The number of air holes 11 on each ventilation pipe 9 can also be designed according to needs, and they are generally arranged at equal intervals. One end of the ventilation pipe 9 is sealed, and the other end is connected to one end of the pipe in the central connecting pipe 3. The pipe is fixed in the central connecting pipe 3, and the central connecting pipe 3 plays a supporting and fixing role. One end of the pipe is connected to the ventilation pipe 9, and the other end is connected to the measuring unit 4 outside the measuring base 1.

[0039] To improve measurement accuracy, the total pressure chamber and the static pressure chamber are each independently structured to measure the pressure difference at different circular positions. The windward side of the total pressure chamber has four measuring holes, and the leeward side of the static pressure chamber has four measuring holes. Specifically, each ventilation pipe 9 is separated into a windward pipe and a leeward pipe by a partition 10. The windward pipe faces the windward direction, and the windward pipe faces the leeward direction. The pipe includes four total pressure chamber pipes 13 and four static pressure chamber pipes 14. Each windward pipe is provided with at least one air hole 11, and generally four air holes 11 are evenly spaced. One end of the windward pipe is sealed, and the other end is connected to a total pressure chamber pipe 13. Each leeward pipe is provided with at least one air hole 11, and one end of the leeward pipe is sealed, and the other end is connected to a static pressure chamber pipe 14, forming a measurement air path.

[0040] In addition, an electric valve can be provided in each full-pressure cavity tube 13 and static pressure cavity tube 14, so that the pressure difference signal at different rings can be opened or closed by the electronic valve according to the air volume and the size of the air outlet area, thereby enhancing the applicability of the air volume hood.

[0041] The measuring unit 4 is fixed to the outer wall of the measuring base 1. A wind pressure sensor is provided in the measuring unit 4 to connect each full pressure cavity tube 13 and static pressure cavity tube 14. The wind pressure sensor is used to measure the wind pressure inside each full pressure cavity tube 13 and static pressure cavity tube 14. The system structure is as follows: Figure 7 As shown, each wind pressure sensor is connected to and outputs a sensing signal to the wind speed transmitter module. The wind speed transmitter module outputs the sensing signal to the main controller, which is connected to the signal output module. The signal output module is a module that interacts with and controls the outside world. The signal output module is connected to and outputs signals to the electric valve, communication module, and display screen, which can control the opening state of the electric valve. At the same time, the communication module and display screen can have input functions to input control instructions to the measurement unit 4. For example, an independent PDA is provided to communicate with the communication unit. The mode is selected by pressing buttons on the PDA. When measuring different air outlet sizes, the working wind pressure sensor can be selectively set to meet the accuracy of the measurement of different air outlet sizes. The system also has a power module, which supplies power to all components.

[0042] In order to supplement the measurement results and reduce the impact of temperature and humidity differences on the data, a temperature and humidity sensor is fixed on the inner wall of the measuring base 1. The temperature and humidity sensor is connected to the main control module of the measuring unit 4 through a wiring harness, and the collected temperature and humidity signals are transmitted to the main control module. The connecting wiring harness can be routed through the central connecting tube 3. A wiring harness tube 12 for the wiring harness to pass through is provided in the center of the central connecting tube 3. Four full-pressure cavity tubes 13 and four static pressure cavity tubes 14 are arranged around the wiring harness tube 12.

[0043] Existing air flow hoods directly measure the average dynamic pressure at multiple points to obtain the average cross-sectional wind velocity, which can lead to errors in the measured air flow. The independently dynamically connected circular flute-shaped wind pressure sensor designed in this invention avoids the measurement errors caused by single-shot averaging and improves accuracy through coefficient calculation. The micromanometer PDA integrates four pressure differential modules, allowing it to simultaneously obtain the pressure differential values ​​of up to four circular flute-shaped averaging tubes, thereby deriving the wind velocity values ​​for each.

[0044] Before starting the measurement, secure the device to the preset position using the bracket 5, align the air volume hood opening with the air outlet, and manually stretch or compress the hood connector 6 to change the relative position of the flute-shaped wind pressure sensor to the base section so that the airflow at the air outlet is evenly distributed in the base section. Measure the average wind speed at different cross-section positions. The differential pressure air volume measurement method includes the following steps:

[0045] Step 1: Collect data from each wind pressure sensor;

[0046] Step 2: Calculate the measured air volume value based on the data;

[0047] Q=S(aV1+bV2+cV3+dV4);

[0048] Q is the air volume, S is the cross-sectional area of ​​the base section where the wind pressure sensor is installed, V1 to V4 are the wind speed values ​​measured by four circular average velocity tubes with different diameters, and a, b, c, and d are the corresponding wind speed coefficients, which are obtained through experimental calibration of multiple sets of standard air volumes and standard instruments.

[0049] This is the formula principle for measuring wind speed using the pressure difference of a circular averaging tube.

[0050] Step 3: Display and output the measured air volume value;

[0051] Step 4: Determine whether the measurement is finished. If so, it ends. If not, return to step 1.

[0052] In the present invention, the circular flute-shaped wind pressure sensors are dynamically connected. By judging the ratio of the air outlet area to the cover opening area, it is manually or automatically set whether to obtain the pressure difference value of the outer circular ring. If the air outlet area is relatively small, the pressure difference signal of the outer circular ring averaging tube should be turned off. The temperature and pressure compensation function is realized by the data of the temperature and humidity sensor inside the cover to obtain the volume air volume of the measured air outlet.

[0053] The present invention is described above by way of example in conjunction with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned method. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the scope of protection of the present invention.

Claims

1. A pressure differential air volume measuring device, comprising a measuring base and an air hood connected by a hood connecting base, wherein the air hood faces the air outlet of the air volume to be measured, characterized in that: The measuring base is provided with a concentric circle bracket, which consists of a vertically arranged central connecting pipe and multiple circles of ventilation pipes coiled around the central connecting pipe. Each of the ventilation pipes is provided with an air hole. One end of the ventilation pipe is sealed, and the other end is connected to one end of the pipe in the central connecting pipe. The other end of the pipe is connected to the measuring unit outside the measuring base. The ventilation pipe is provided with four circles, and each of the ventilation pipes is separated into a windward pipe and a leeward pipe by a partition. The pipe includes four full-pressure cavity pipes and four static-pressure cavity pipes. Each of the windward pipes is provided with at least one air hole. One end of the windward pipe is sealed, and the other end is connected to a full-pressure cavity pipe. Each of the leeward pipes is provided with at least one air hole. One end of the leeward pipe is sealed, and the other end is connected to a static-pressure cavity pipe. The measuring unit is provided with a wind pressure sensor connected to each full-pressure cavity tube and static pressure cavity tube, each wind pressure sensor is connected to and outputs a sensing signal to the wind speed transmission module, the wind speed transmission module outputs the sensing signal to the main controller, the main controller is connected to the signal output module, the signal output module is connected to and outputs the signal to the electric valve, communication module and display screen, and the power supply module in the measuring unit supplies power to all components; A temperature and humidity sensor is fixed to the inner wall of the measuring base, and the temperature and humidity sensor is connected to the measuring unit via a wiring harness. A wiring harness tube is provided at the center of the central connecting tube for the wiring harness to pass through. The four full-pressure cavity tubes and the four static-pressure cavity tubes are arranged around the wiring harness tube. A fixed shaft is provided at the top end of the central connecting tube and is fixed to the inner wall of the measuring base via the fixed shaft. The measuring base is the core of the entire device. Concentric circle brackets are fixed inside the measuring base. Each layer of the concentric circle brackets is a measuring point. The independent annular average velocity tube sensor is used to change the multi-point average wind speed calculation method. The average wind speed at the position of the ring with different radius is measured separately, and the cross-sectional average wind speed is calculated using the data curve fitting method. The four-ring measurement data is calibrated to display the measured air volume value. A grid plate plug-in arranged in a grid shape is fixed in the wind hood. The grid plate plug-in is a strip-shaped plate that intersects perpendicularly with each other and is arranged in the wind hood to form a plurality of independent air ducts.

2. The pressure differential air volume measuring device according to claim 1, characterized in that: An electric valve is provided in each of the total pressure cavity tube and the static pressure cavity tube.

3. The pressure differential air volume measuring device according to claim 2, characterized in that: The cover connecting seat is a bellows, and a bracket for installation and fixation is fixed on the outer surface of the measuring base.

4. A method for measuring differential air volume based on the differential air volume measuring device according to any one of claims 1 to 3, characterized in that: The following steps are involved: Step 1: Collect data from each wind pressure sensor; Step 2: Calculate the measured air volume value based on the data; Step 3: Display and output the measured air volume value; Step 4: Determine whether the measurement is finished. If so, it ends. If not, return to step 1.

5. The pressure differential air volume measurement method according to claim 4, characterized in that: The calculation method of step 2 is as follows: the measured air volume value is Q; Q=S(aV1+ bV2 +cV3 +dV4); Where S is the cross-sectional area of ​​the base section where the wind pressure sensor is installed; V1~V4 are the wind speed values ​​measured in four different ventilation ducts; a, b, c, and d are the corresponding wind speed coefficients respectively.

6. The pressure differential air volume measurement method according to claim 5, characterized in that: The measured air volume value Q is compensated by the acquired temperature value and humidity value to obtain the measured air volume of the air outlet.

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