JP6251315B2 - Airflow measuring device - Google Patents

Description

  The present invention relates to an air volume measuring device that measures an air volume at a ventilation opening of a ventilation fan, an air conditioner, a factory facility, or the like.

  Starting with “Ventilation Fan (JISC9603)” and “Air Conditioning / Ventilation Equipment Airflow Measurement Method (JISA1431)” defined in Japanese Industrial Standards, for example, Patent Document 1 and Patent Document 2 measure airflow of ventilation fans and air vents. Many proposals have been made.

  For example, when actually measuring the intake air volume of a ventilation fan in accordance with the measurement method of JIS C9603, a JIS standard air volume measuring device “suction nozzle” is attached to the suction side of the auxiliary fan, and “auxiliary fan” is connected via a joint member “canvas”. Connect to. Furthermore, on the discharge port side of the auxiliary fan, it is connected to a duct via a canvas, and is connected to an “air tank” with a ventilation fan via this duct.

  As described above, the flow path of the air to be measured is composed of various members and has a connected structure. In such a measurement environment, when measuring the air volume of the ventilation fan, the important point is to ensure airtightness so that air does not leak or be sucked in from the air suction area to the discharge area of the ventilation fan. There is to do.

  On the other hand, when measuring the air volume before and after the blower, it is well known that the measurement environment can be improved by installing a rectifier in both the discharge and suction side of the blower.

  For example, according to JISB 8330, when measuring on the discharge side of the blower, the rectifier is provided at a position separating a straight pipe portion (> 2D) having a length exceeding twice the diameter (D) of the blower outlet. According to this condition, since a considerable straight pipe portion is required to measure the air volume in the downstream area of the auxiliary fan, there is a problem that the apparatus is enlarged and the mobility is impaired.

Japanese Utility Model Publication No. 60-93919 (microfilm of Japanese Utility Model Application No. 58-186062) JP 2004-257842 A

  In view of this point, the present invention can easily assemble the apparatus without being troubled by air leakage or suction phenomenon related to the airtightness of the component parts, and can improve the mobility by making the apparatus compact and measure the air volume. An object of the present invention is to provide an air volume measuring device capable of stabilizing the flow state of the flow path cross section.

  The air volume measuring device according to claim 1 is an air volume measuring device for measuring the air volume at the air inlet by applying a wind collecting hood for collecting air to the outlet or suction port of the air outlet. An auxiliary fan for compensating for fluctuations in the airflow caused by applying the airflow, an airflow measuring device installed on the discharge side of the auxiliary fan, a duct on the discharge side of the air collecting hood, and an intake side of the airflow measuring device. And an airtight chamber connected in an airtight manner, wherein the auxiliary fan is airtightly accommodated in the chamber.

An air volume measuring device according to claim 2 is the air volume measuring device according to claim 1, comprising a rectifier between the auxiliary fan and the air volume measuring device,
The rectifying device is provided at a position within twice (2D) the diameter (D) of the discharge duct of the auxiliary fan from the fan of the auxiliary fan.

  An air volume measuring device according to claim 3 is the air volume measuring device according to claim 1 or 2, wherein the air volume measuring device is connected to a wall surface along the flow axis direction of the air flow of the auxiliary fan of the chamber for connection with a wind collecting hood. A connection port is provided.

  The air flow measuring device according to claim 4 is the air flow measuring device according to claim 3, wherein a wind direction adjusting plate is installed between the connection port and the suction port of the auxiliary fan in a direction crossing the axis of the connection port. It is characterized by being.

  The air volume measuring device according to claim 5 is the air volume measuring device according to claim 3 or 4, wherein the air volume measuring device is an upstream region in the flow axis direction of the air flow of the auxiliary fan, and is orthogonal to the flow axis direction of the chamber. The wall surface is provided with a second connection port for connection to the air collecting hood.

  An air flow measuring device according to claim 6 is the air flow measuring device according to any one of claims 1 to 5, wherein the air flow measuring device comprises a flat plate and a pipe vertically connected to the flat plate, The wind collecting hood is provided with a pressure detection body in which a measurement hole having a hole diameter equal to or less than ½ of the thickness of the flat plate is formed in the flat plate, and a connection hole communicating with the measurement hole is formed in the pipe. An internal static pressure is detected through the pressure detector.

  According to the present invention, since the auxiliary fan is hermetically housed in the airtight chamber that is hermetically connected to the discharge side of the air collecting hood and the suction side of the air flow measuring device, it is flexible with respect to the chamber. By simply connecting the air collecting hood via a duct or the like, the apparatus can be easily assembled without being bothered by air leakage and suction phenomena related to the airtightness of the components. Further, the device becomes compact and the mobility becomes high. The chamber is an air tank, and the potential of the auxiliary fan can be extracted by reducing the resistance of the air passing through the air tank. Stabilize.

It is a partially fractured side view of the air volume measuring device of the embodiment of the present invention. It is a front view of the air volume measuring device of the embodiment of the present invention. It is a rear view of the air volume measuring apparatus of embodiment of this invention. It is a top view of the air volume measuring device of the embodiment of the present invention. It is a figure which shows the example of a connection of the 1st connection port and flexible duct in the air volume measuring apparatus of embodiment of this invention. It is the front view and partial crushing side view of the pressure detection body in embodiment of this invention. It is a figure which shows the outline of the flow of the air in the chamber in the air volume measuring apparatus of embodiment of this invention. It is a figure explaining the problem when there is no wind direction adjustment board in the air volume measuring apparatus of embodiment of this invention. It is a figure which shows the example of a connection of the 2nd connection port and flexible duct in the air volume measuring apparatus of embodiment of this invention. It is a figure explaining the problem when there is no 2nd connection port in the air volume measuring apparatus of embodiment of this invention. It is a figure which shows the example of a connection at the time of calibration of the air volume measuring apparatus of embodiment of this invention.

  Next, an embodiment of the air flow measuring device of the present invention will be described with reference to the drawings. FIG. 1 is a partially fragmented side view of the air volume measuring device of the embodiment, FIG. 2 is a front view of the air volume measuring device of the embodiment, FIG. 3 is a rear view of the air volume measuring device of the embodiment, and FIG. It is a top view of an apparatus. Note that the concept of “upper and lower” in the following description corresponds to the upper and lower sides in the drawing of FIG.

  The air volume measuring device 100 of this embodiment measures the air volume at a ventilation opening (air outlet) of a ventilation fan, an air conditioner, a factory facility, etc., and has casters 20 at the four corners on the back surface of the substrate 10. And a chamber 1 having a rectangular parallelepiped shape close to a cube. The air volume measuring device 100 includes an auxiliary fan 2, a rectifier 3, a canvas duct 4, an air volume measuring device 5, and a reducer 6. An auxiliary fan 2, a rectifying device 3 and a canvas duct 4 are accommodated in the chamber 1.

  In the chamber 1, a circular first suction hole 1Aa is formed near the front surface of the top plate 1A, a circular second suction hole 1Ba is formed near the lower side of the front plate 1B, and the back plate 1C A circular discharge hole 1Ca is formed on the lower side. A cylindrical first connection port 11 is attached to the first suction hole 1Aa, and a cylindrical second connection port 12 is attached to the second suction hole 1Ba. A cylindrical discharge port 13 is attached to the discharge hole 1Ca. The first suction hole 1Aa and the first connection port 11 are centered on the axis L1, the second suction hole 1Ba and the second connection port 12 are centered on the axis L2, and the discharge hole 1Ca and the discharge port 13 are the axis L3. Is the center. The first connection port 11, the second connection port 12, the discharge port 13, and the chamber 1 are joined in an airtight manner, and the auxiliary fan 2 is housed in the chamber 1 in an airtight manner.

  1 to 4 show one usage pattern of the air flow measuring device 100 of the embodiment. In this usage pattern, a flexible duct 11 a is connected to the first connection port 11. And the 1st connection port 11 is connected with the below-mentioned wind collection hood 50 through this flexible duct 11a. Moreover, in this usage pattern, the second connection port 12 is sealed by the lid 12b.

  The auxiliary fan 2 is an axial fan that blows air along the axis L01. The auxiliary fan 2 includes a fan 22 in a cylindrical discharge duct 21. That is, the axis L01 is the flow axis direction of the air flow of the auxiliary fan 2. The suction side of the auxiliary fan 2 faces the second suction hole 1Ba and the second connection port 12. The rectifier 3 is attached to the discharge side of the discharge duct 21 of the auxiliary fan 2, and the rectifier 3 and the discharge hole 1Ca are connected by the canvas duct 4. Further, an air flow measuring device 5 is connected to the discharge port 13, and a reducer 6 is connected to the outlet side of the air flow measuring device 5. The second connection port 12 (second suction hole 1Ba), the auxiliary fan 2, the rectifying device 3, the canvas duct 4, the discharge port 13 (discharge hole 1Ca), and the air flow measuring device 5 are arranged coaxially. Yes. That is, the axis L2 of the second connection port 12, the axis L01 of the auxiliary fan 2, the axis L3 of the discharge port 13, and the axis L02 of the air flow measuring instrument 5 are in a straight line.

  As shown in FIG. 1, the rectifier 3 is provided at a position within twice (2D) the diameter (D) of the discharge duct 21 from the fan 22 of the auxiliary fan 2. The rectifier 3 is constituted by a number of rectifier plates parallel to the axis L01 of the auxiliary fan 2.

  The air flow measuring device 5 is configured by accommodating a rectifying grid 52 and a sensor unit 53 in a cylindrical casing 51 having the same diameter as the discharge port 13. The rectifying grid 52 prevents a swirling flow in the casing 51, and the sensor unit 53 detects, for example, the total pressure of air in the upstream pipe, and detects a pressure lower than the average static pressure in the downstream pipe, The flow rate is detected from the pressure difference between the two pressures.

  The first connection port 11 (first suction hole 1Aa) on the top plate 1A side of the chamber 1 and the auxiliary fan 2 are arranged such that the axis L1 and the axis L01 are orthogonal to each other. Further, a wind direction adjusting plate 14 that is parallel to the top plate 1A is installed in the chamber 1 so as to face the top plate 1A (first suction hole 1Aa). The wind direction adjusting plate 14 extends from the back surface of the front plate 1B toward the back plate 1C, and a rectangular channel 14a is secured between the end of the wind direction adjusting plate 14 and the back plate 1C. Yes.

  The top plate 1 </ b> A of the chamber 1 is a parallel wall surface along the axis L <b> 01 of the auxiliary fan 2. That is, the connection port 11 for connecting with the air collecting hood 50 is provided in the top plate 1A which is a wall surface along the flow axis direction of the air flow of the auxiliary fan 2 of the chamber 1. A wind direction adjusting plate 14 is installed between the connection port 11 on the top plate 1 </ b> A side and the suction port of the auxiliary fan 2 in a direction crossing the axis L <b> 1 of the connection port 11. In addition, a second airflow hood 50 is connected to the front plate 1B which is a wall surface orthogonal to the axis L01 of the chamber 1 in the upstream axial direction of the airflow of the auxiliary fan 2, that is, in the upstream direction of the axis L01. A connection port 12 is provided.

  A control box 30 containing a controller for controlling the entire air volume measuring device 100 is attached to the back plate 1 </ b> C of the chamber 1. A display box 40 for displaying the measured differential pressure and flow rate and outputting differential pressure and flow rate data is mounted on the top plate 1A of the chamber 1.

  FIG. 5 is a diagram illustrating a connection example of the first connection port 11 and the flexible duct 11a in the air flow measuring device 100 of the embodiment. In the following drawings, reference numerals are given only to main members, and reference numerals of other members are omitted as appropriate. As shown in FIG. 5, a wind collecting hood 50 is connected to the flexible duct 11a. The air collecting hood 50 is a cube-shaped hood having an opening on one side, and has a connection port 50a for connecting the flexible duct 11a to a lower portion opposite to the opening. Further, pressure detectors 7 for detecting static pressure in the air collecting hood 50 are attached to the four side surfaces of the air collecting hood 50.

  FIG. 6 is a front view (FIG. 6A) and a partially crushed side view (FIG. 6B) of the pressure detector 7. The pressure detector 7 is formed by integrally forming a disk-shaped flat plate 71 and a pipe 72 connected to the flat plate 71 perpendicularly. A measurement hole 71a is formed in the center of the flat plate 71. The diameter of the measurement hole 71a is ½ or less of the thickness of the flat plate 71, and the length of the measurement hole 71a is more than twice the hole diameter. Yes. In addition, a connection hole 72 a communicating with the measurement hole 71 a is formed in the pipe 72, and the measurement hole 71 a and the connection hole 72 a pass through the pressure detection body 7. The pipe 72 of each pressure detector 7 is connected to a differential pressure gauge in the display box 40 via a tube or the like, and differential pressure data output from the display box 40 is connected to an inverter in the control box 30. .

  With the above-described configuration, the air collecting hood 50 is attached to the air outlet to be measured, and the air volume is measured. That is, the rotational speed of the auxiliary fan 2 is adjusted by an inverter or the like so that the static pressure in the air collecting hood 50 detected via the pressure detector 7 becomes equal to the pressure outside the air collecting hood 50, that is, the atmospheric pressure. Automatic control. That is, control is performed so as to remove the resistance component by the air collecting hood 50 against the flow of air blown out from the air control port. Thereby, the air blown out from the air control port flows into the chamber 1 through the air collecting hood 50, the flexible duct 11 a, and the first connection port 11. In the chamber 1, the air flows from the space above the air direction adjusting plate 14 into the space below the air direction adjusting plate 14 through the rectangular channel 14 a. This air flows from the suction side to the discharge side of the auxiliary fan 2, is rectified by the rectifier 3, and flows from the discharge port 13 to the air volume measuring device 5. Then, the air volume is measured by the air volume measuring device 5 and the measured air volume is displayed in the display box 40.

  FIG. 7 is a diagram showing an outline of the flow of air in the chamber 1 in the air volume measuring device 100 of the embodiment. The air blown out from the air restriction port flows into the chamber 1 from the first connection port 11, and a wind direction adjusting plate 14 is installed in the chamber 1, and a rectangular flow path 14 a by the wind direction adjusting plate 14 is The auxiliary fan 2 is located on the discharge side. On the other hand, since the discharge side of the auxiliary fan 2 is isolated from the internal space of the chamber 1 by the rectifying device 3 and the canvas duct 4, the air flowing into the space below the wind direction adjusting plate 14 from the rectangular flow path 14a is It flows from the discharge side (rear side) to the suction side through the outer periphery of the auxiliary fan 2. Therefore, a stable flow of air can be sent to the rectifier 3 by the auxiliary fan 2.

  On the other hand, as shown in FIG. 8, for example, in the air volume measuring device 200 without the air direction adjusting plate 14, the state of the airflow flowing from the flexible duct 11a into the chamber 1 'varies greatly depending on the handling of the flexible duct 11a. For example, as shown in FIGS. 8 (A) and 8 (B), the fluctuation of the airflow also affects the wind speed distribution in the downstream area on the auxiliary fan 2 'side. That is, the wind speed distribution in the downstream area of the auxiliary fan 2 'flowing from the connection port 11' varies depending on the direction of deflection of the flexible duct 11a and the degree of curvature (curvature). Therefore, a stable velocity distribution cannot be obtained. However, in the embodiment, there is no such problem due to the wind direction adjusting plate 14 and the flow path 14a.

  In other words, in the embodiment, the airflow flowing into the auxiliary fan 2 is stabilized by installing the air direction adjusting plate 14 in the chamber 1 in which the auxiliary fan 2 is housed, regardless of the direction of the flexible duct 11a and the bending state. Since the stable flow in the suction area leads to stabilization of the airflow state on the fan discharge side, the influence of the airflow on the air volume measuring device 5 installed in the fan discharge area is also limited.

  FIG. 9 is a diagram illustrating a connection example of the second connection port 12 and the flexible duct 12a in the air volume measuring device 100 of the embodiment. In this usage pattern, the flexible duct 12 a is connected to the second connection port 12. The second connection port 12 is connected to the wind collecting hood 50 through the flexible duct 12a. Moreover, in this usage pattern, the first connection port 11 is sealed by the lid 11b.

  The air vents are often installed at various places such as the ceiling and feet, and the installation positions are mixed even in the same facility. In such a measurement environment, the convenience can be enhanced by connecting the air collecting hood 50 and the chamber 1 with a flexible duct or the like. However, as shown in FIG. 10, when the connection port 11 'with the wind collecting hood 50 is provided only on one surface of the chamber 1', the measurement of the air volume at the outlet near the foot increases the handling of the flexible duct 11a. The overall wind resistance increases. As a result, the capacity of the auxiliary fan cannot be exhibited and a predetermined air volume cannot be secured.

  On the other hand, in the air volume measuring device 100 of the embodiment, since the second connection port 12 is provided in addition to the first connection port 11, the flexible duct 11a is linearly connected to the outlet near the foot. There is no problem as described above. That is, the flexible duct 11a that optimizes the distance between the air collecting hood 50 applied to the ventilation fan or the air control port and the connection port can be routed, and excessive flow resistance can be reduced. As a result, the capacity of the auxiliary fan 2 can be reduced, and the fan weight and cost can be reduced.

  In addition, since the air volume measuring device 100 of the embodiment is configured as described above, the following advantageous effects can be obtained. Conventionally, when building an air flow measurement device, it took a lot of time to carefully assemble and check the device to ensure the airtightness of the auxiliary fan, canvas, and joints that are prone to air leakage and suction. . On the other hand, in the embodiment, since the auxiliary fan 2, the rectifier 3 and the canvas duct 4 are housed in the chamber 1 in an airtight manner, the airtightness can be ensured and the assembly and checking operations of the device are facilitated. .

  Moreover, since the rectifier 3 is installed in the vicinity of the discharge side of the auxiliary fan 2, an effect can be expected against swirling flow and significant drift, which are problems in air flow measurement, and the device can be made more compact and lighter. Increases nature.

  In the embodiment, since the static pressure in the wind collecting hood 50 is detected by using the pressure detecting body 7, it is installed depending on the direction of the air flow in the hood as in the conventional detection method such as a Pitot tube. It is possible to implement a pressure detection method that does not require changing the direction. In the method of directly providing the measurement hole for detecting the static pressure on the wall surface of the air collecting hood 50, the hole diameter of the measurement hole needs to be ½ or less of the wall thickness in order to accurately measure the static pressure. Therefore, when the wall surface is thin, the hole diameter of the measurement hole is made smaller, and the risk of processing difficulties and hole clogging increases. For this reason, if the thickness of the wall surface is increased, the air collecting hood becomes heavy, which causes a handling problem. On the other hand, in the embodiment, since the pressure detector 7 as described above is used, there is no such problem.

  Note that the air volume measuring device 100 of the embodiment can easily calibrate the air volume measuring device 5. The calibration method is as follows. As shown in FIG. 11A, a JIS standard suction nozzle A is attached to the tip of the flexible duct 11a (or the first connection port 11 or the second connection port 12). The shape of the suction nozzle A is determined by the JIS standard, and the correlation between the pressure detected via the pressure detector A1 and the air volume in the suction nozzle A is determined. As shown in FIG. 11 (B), the JIS standard suction nozzle A can measure the accurate air volume even if the direction is changed. Then, by using the inverter in the control box 30 and controlling the rotational speed of the auxiliary fan 2, the air volume is changed in several steps, and the air volume obtained by the suction nozzle A in each air volume area and the air volume measuring device 5. Check the detected air volume. Further, it is confirmed that the same result can be obtained even if the direction of the suction nozzle A is changed. Based on the measurement data obtained in this way, the indicated air volume value of the air volume measuring device 5 can be brought close (corrected) to the air volume indicated by the suction nozzle A of the JIS standard. Thereby, more accurate airflow measurement can be performed.

  As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to these embodiments, and the design can be changed without departing from the scope of the present invention. Is included in the present invention.

1 Chamber 1A Top plate 1Aa First suction hole 1B Front panel 1Ba Second suction hole 1C Rear panel 1Ca Discharge hole 11 First connection port 11a Flexible duct 11b Lid 12 Second connection port 12b Lid 13 Discharge port 14 Wind direction Adjustment plate 14a Rectangular flow path 2 Auxiliary fan 21 Discharge duct 22 Fan 3 Rectifier 4 Canvas duct 5 Air flow meter 51 Casing 52 Rectifier grid 53 Sensor unit 6 Reducer 7 Pressure detector 71 Flat plate 72 Pipe 71a Measuring hole 72a Connection hole 50 Air collecting hood 100 Air flow measuring device L1 Axis L2 Axis L3 Axis L01 Axis L02 Axis

Claims (6)

An air volume measuring device that applies an air collecting hood for collecting air to the air outlet or the air inlet of the air inlet and measures the air volume at the air outlet,
An auxiliary fan for compensating for fluctuations in the air volume caused by applying the air collecting hood, an air volume measuring device installed on the discharge side of the auxiliary fan, a duct on the discharge side of the air collecting hood, and the air flow measuring instrument. An airtight chamber that is airtightly connected to the suction side,
The air flow measuring device, wherein the auxiliary fan is housed in the chamber in an airtight manner. A rectifier is provided between the auxiliary fan and the air flow measuring device,
2. The air flow measurement according to claim 1, wherein the rectifying device is provided at a position within twice (2D) of a diameter (D) of a discharge duct of the auxiliary fan from the fan of the auxiliary fan. apparatus.   The air volume measuring device according to claim 1, wherein a connection port for connecting to the air collecting hood is provided on a wall surface of the chamber along the flow axis direction of the air flow of the auxiliary fan. .   The air flow measuring device according to claim 3, wherein a wind direction adjusting plate is installed between the connection port and the suction port of the auxiliary fan in a direction intersecting with the axis of the connection port.   A second connection port for connecting to the air collecting hood is provided in the upstream area in the flow axis direction of the air flow of the auxiliary fan and on the wall surface orthogonal to the flow axis direction of the chamber. The air volume measuring device according to claim 3 or 4, characterized by the above. A pressure detector comprising a flat plate and a pipe connected perpendicularly to the flat plate, wherein the flat plate is formed with a measurement hole having a hole diameter equal to or less than ½ of the thickness of the flat plate, and the pipe is A pressure detector having a connection hole communicating with the measurement hole;
The air volume measuring device according to any one of claims 1 to 5, wherein a static pressure in the air collecting hood is detected through the pressure detector.

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