JPH11118547A - Air capacity measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a size in the flow direction of fluid, miniaturize an apparatus, and relieve the restriction of fixing into a pipe by arranging static pressure measurement holes of a static pressure measurement detecting member toward the lower stream side. SOLUTION: A plurality of fluid pressure detectors 1 are arranged in parallel, in the lower stream side of a flow straightener 11 installed in a casing 10. As to the detector 1, two fluid pressure detecting members constituted of flat rectangular hollow hexahedrons are connected back to back, such that pressure leading-out ports have the same directions and pressure measurement holes have opposite directions. The holes positioned in the upper stream side are total pressure measurement holes, and a total pressure detecting member is constituted. The holes positioned in the lower stream side are static pressure measurement holes, and a static pressure detecting member is constituted. Since the static pressure measurement holes are arranged in the lowest stream end, apparent dynamic pressure becomes larger than real dynamic pressure, by the effect of vortex formed by itself. In particular, in a low wind velocity region where the dynamic pressure is small, reading error of pressure can be estimated to be small. Since static pressure is measured in the vertex formed by itself, influence of the vertex from the flow straightener 11 is reduced, and measurement precision is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air flow measuring device for measuring an air flow flowing in a pipeline.

[0002]

2. Description of the Related Art An air flow measuring device provided with a rectifier on the upstream side of a casing and a fluid pressure detector such as a pitot tube on the downstream side is known (see Japanese Utility Model Laid-Open No. 60-80316).

[0003]

In this known air flow measuring device, the static pressure measuring hole of the fluid pressure detector is opened perpendicularly to the flow direction of the fluid, so that a stable flow without vortex is generated. Measurement is required. Therefore, in order to avoid the influence of the vortex generated from the rectifier located in the upstream area, it is necessary to provide a sufficient straight pipe portion between the rectifier and the fluid pressure detector.
And, in general, since the static pressure measurement hole of the fluid pressure detector is opened so as to be oriented in a direction perpendicular to the flow of the fluid for the purpose of detecting the true static pressure in the flow path, as described above, When the differential pressure detecting element is provided immediately after the rectifier, it is greatly affected by the eddy current generated immediately after the rectifier. Therefore, there is a problem that the measurement accuracy of the detected pressure is deteriorated.

[0004] From the above, JIS of Japanese Industrial Standard
In the test and inspection method of the B 8330 blower, the distance between the rectifier and the fluid pressure detector is set to be larger than the pipe diameter of the casing so as not to be affected by the eddy current after the rectifier. I have. This causes a problem in the air flow measuring device having a built-in rectifier that the length of the fluid in the flow direction is long, the device is inevitably increased in size, and the installation space for the device is increased. Furthermore, the position for measuring the air volume in the pipeline is generally not necessarily the location where the pipeline is a straight pipe, but rather the location where measurement must be performed in a narrow place immediately after a bent pipe or a branch pipe. For this purpose, there is a problem that an air flow measuring device that can reduce the flow direction dimension of the air flow measuring device itself and that can measure even a place where the straight pipe dimension is short upstream of the device is required.

The present invention has been made in view of the above problems, and in particular, aims to reduce the size of the apparatus in the flow direction of the fluid, thereby reducing the size of the apparatus.
It is an object of the present invention to provide a novel flow rate measuring device that can be used in a wide range of applications while relaxing restrictions on installation in a pipeline.

[0006]

According to the present invention, there is provided a flow measuring apparatus comprising:
An air flow measuring device provided with a rectifier on an upstream side in a casing and a fluid pressure detector on a downstream side, wherein the fluid pressure detector is a total pressure measuring and detecting device formed of a hollow body along a flow direction of a fluid. Body and static pressure measurement sensor, with the total pressure measurement hole of the total pressure measurement sensor facing upstream of the fluid flow and the static pressure measurement hole of the static pressure measurement sensor facing downstream of the fluid flow It is characterized by being positioned.

[0007] It is desirable that the total pressure measurement detector and the static pressure measurement detector are flat, substantially rectangular hollow bodies. It is preferable that the total pressure measurement detector and the static pressure measurement detector are formed in the same shape and the same size, and they are connected back to back. Further, the total pressure measurement detector and the static pressure measurement detector may be integrally formed with the same shape and the same dimensions.
It is preferable that the above-mentioned total pressure measuring detector and the static pressure measuring detector are formed in the same shape and the same size, and they are arranged with a small space between them back to back.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described based on embodiments shown in the drawings. 1 and 2 show an embodiment in which the casing is square. In the figure, reference numeral 10 denotes a casing, and a rectifier 11 is mounted on an upstream side thereof. The structure of the rectifier 11 may be a conventionally known honeycomb structure, a mesh structure, or an approximate honeycomb structure in which corrugated corrugated plates are alternately laminated between flat plates. In any case, it is desirable that the rectifier be made of stainless steel so as to withstand various environments in terms of enhancing durability.

In the figure, reference numerals 1 and 1 denote fluid pressure detectors, and a plurality of fluid pressure detectors are arranged and fixed in parallel downstream of the rectifier 11.
As shown in FIGS. 4 and 5, the fluid pressure detector is configured by connecting fluid pressure detectors 1a and 1b having the same shape and the same dimensions back to back. The fluid pressure detectors 1a and 1b are flat and substantially rectangular hollow hexahedrons, and the flat upper wall 2 and lower wall 3, the left and right closing walls 4 and 4, and the fluid It is formed by front and rear walls 5, 5 located either before or after in the flow direction. The closing wall 4 on one of the left and right closing walls 4 and 4
A pressure outlet 6 is provided in one of the front and rear walls 5 and 5.
Are provided with a plurality of pressure measurement holes 7. Then, the respective pressure outlets 6, 6 are positioned in the same direction, and are connected back to back such that the respective pressure measurement holes 7, 7 are in opposite directions. Thus, the one located on the upstream side of the flow is a total pressure measurement detector serving as a total pressure measurement hole, and the one located on the downstream side is a static pressure measurement detector serving as a static pressure measurement hole.
In the illustrated embodiment, the one side wall 5 in which the pressure measurement hole 7 is formed has an arc-shaped cross section. However, the side wall 5 does not necessarily have to be arc-shaped, but may be a flat plate positioned at right angles to the flow. Further, the fluid pressure detector may be formed in a pipe shape without being flat.

In the above-described fluid pressure detector 1, since the static pressure measuring hole is located at the most downstream end, the apparent static pressure is lower than the true static pressure due to the vortex generated by the fluid pressure detector itself. The apparent dynamic pressure, which is the difference between the pressure and the apparent static pressure, is greater than the true dynamic pressure. In particular, in a low wind speed region where the dynamic pressure decreases, the pressure reading error rate can be estimated to be smaller than that of a device that detects the true dynamic pressure. Further, by measuring the static pressure in the vortex generated by the fluid pressure detector itself, the influence of the vortex generated from the rectifier is reduced, and improvement in measurement accuracy can be expected. Further, by making the fluid pressure detector 1 a flat hollow body, the fluid pressure detector itself has an effect of regulating the flow of the fluid, which is effective.

In the embodiment shown in FIG.
Are formed in the left and right open portions of the fluid pressure detecting body, for example, by fitting a cap-shaped casting or the like. The use of a sealing material and an adhesive material minimizes welding work and saves work steps. Each of the pressure outlets 6 protrudes out of the casing 10, and the left and right closing walls 4 are fixed to the casing by screws. The pressure outlets 6 of the plurality of fluid pressure detection devices are connected by a single communication pipe 12, and an average total pressure or an average static pressure is taken out by an average pressure outlet 18. Also, as shown in FIG. 3, the communication pipe 12 is covered with a cover 13, and the left and right closing walls 4 are attached integrally with the cover 13 with screws 14. Further, the communication pipe may be formed in a rubber tube shape, and the pressure outlet 6 may be simply inserted into the communication hole formed in the tube in an airtight manner.

FIG. 6 shows an embodiment of the device of the present invention in a round shape. As in the case of the square type, the rectifier 11 is arranged on the upstream side, and the fluid pressure detector 1 is arranged on the downstream side. As shown in FIGS. 6 to 8, the fluid pressure detector 1 mounted in a round shape is
Combined in a cross shape. In the illustrated embodiment, four fluid pressure detectors are connected to a sensor socket 15 made of a hollow body.
And radially connected around the socket.
The respective total pressure measurement detectors and the respective static pressure measurement detectors are communicated via the hollow portion 16 of the sensor socket 15 so as to equalize the total pressures and the static pressures. A pressure outlet pipe is provided to the total pressure outlet 6 and the static pressure outlet 6 of one of the four total pressure measurement detectors or one of the four static pressure measurement detectors so as to penetrate the inside of each measurement detector. 17 is connected, the inner end thereof is opened in the sensor socket 15, and an average total pressure or an average static pressure of the four fluid pressure detectors is taken out from an average pressure outlet 18.

Although not shown in the drawings, a plurality of fluid pressure detectors radially connected around the sensor socket are provided.
A plurality of fluid pressure detectors may be provided in different sections perpendicular to the flow direction of the fluid, and the plurality of connected fluid pressure detectors may be provided at positions not overlapping the upstream side and the downstream side in the fluid flow direction.

FIGS. 9 and 10 show a device according to the present invention in which a space 8 is provided slightly between the total pressure measuring detector 1a and the static pressure measuring detector 1b. In the fluid pressure detector 1 provided with the space 8, the directivity in the flow direction can be reduced, and the yaw characteristics at the angle of attack can be improved. From this, coupled with the effect of the rectifier located upstream, it was possible to make the device less likely to cause an error in the detected pressure even under the condition of significant drift or unsteady flow where the flow direction is not stable. . The results obtained from the experiment are displayed as a table, which is shown in FIG. In this experiment, a known device (referred to as an A device) already in practical use and fluid pressure detectors 1a and 1b were connected back to back as shown in FIGS.
Apparatus shown in FIG. 6 (referred to as apparatus B) and FIGS. 9 and 10
(Compared with the device C). According to this, a good result was obtained between the attack angles of 0 to 18 degrees. The example used in this experiment is as follows. A fluid pressure detector having a thickness of 10 mm, a width of 30 mm, and a length of 200 mm is connected back to back with the embodiment shown in FIG. Using a device having the same dimensions as the above B device and using a device having the same size and arranged between the fluid pressure detecting members via a space of 2 mm, the device was placed in a 200 mm × 300 mm duct, and tested at a wind speed of 11 m / sec. .

In the device of the present invention, the fluid pressure detector is formed by a hollow body having a shape along the flow direction of the fluid, and the static pressure measurement hole of the static pressure measurement detector is positioned toward the downstream side. The pressure is detected in the vortex induced by the fluid pressure detector itself. This reduces the effect of eddy currents after the rectifier, and thus reduces the size between the fluid pressure detector and the rectifier. That is, as shown in FIG. 2, the relationship between the dimension L between the rectifier and the fluid pressure detector and the pipe diameter D of the casing is L <D shorter than the JIS standard.
It can be.

FIG. 12 shows the results of a functional test performed by the embodiment shown in FIG. 6 of the air flow measuring device of the present invention. This functional test uses a 412 mm diameter round device, a device of the present invention with a rectifier having a honeycomb structure downstream of the fan,
1. Install a device without rectifier, wind speed 23 m / s and 2.
It was tested at 5 m / s. As a result, due to the presence of the rectifier, the error rate with respect to the true wind speed was extremely small, and a highly accurate measurement result was obtained. Furthermore, in the fluid pressure detector, if the total pressure measurement detector and the static pressure measurement detector are formed into a structure having the same shape and the same dimensions, and are arranged back to back, the production and processing thereof are easy. In addition, if the material of the differential pressure detector is aluminum, resin, or the like, it can be extruded. Therefore, it is possible to form a fluid pressure detector in which the total pressure measurement detector and the static pressure measurement detector are integrated. did it.

[0017]

As described above, in the device according to the present invention, the static pressure measurement hole of the static pressure measurement detector is arranged toward the downstream side of the flow of the fluid, so that the influence of the vortex of the flow of the fluid generated from the rectifier. This has the advantage of being less susceptible to inconvenience, and the measurement error rate can be reduced in combination with the rectification effect of the rectifier. as a result,
This eliminates the need to provide a sufficient straight pipe section between the rectifier and the fluid pressure detector, and has the effect of making the measuring device compact. Therefore, it is possible to mount the device immediately after the fan or the elbow in the pipeline, and it is possible to relax the limitation of the installation of the device in the pipeline, and to obtain a large practical effect that it can be applied to a wide range of applications.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view of an embodiment of a square-shaped device of the present invention.

FIG. 2 is a partially cutaway side view of the same.

FIG. 3 is a partially cutaway side view showing an embodiment of a fluid pressure detector.

FIG. 4 is a partially cutaway perspective view showing a basic structure of a fluid pressure detector.

FIG. 5 is a sectional view of the basic structure of the above.

FIG. 6 is a partially cutaway perspective view showing a round-shaped embodiment of the present invention.

FIG. 7 is a partially cutaway side view of a fluid pressure detector mounted in a round shape.

FIG. 8 is a partially cutaway front view of a main part of the above.

FIG. 9 is a partially cutaway perspective view of a square-shaped embodiment in which a slight space is provided between fluid pressure sensing elements.

FIG. 10 is a partially cutaway perspective view of the same circular embodiment.

FIG. 11 is a table obtained by an experiment comparing the yaw characteristics of the angle of attack.

FIG. 12 is a graph showing the results of performing a functional test on the apparatus with and without a rectifier according to the embodiment shown in FIG. 6;

FIG. 13 shows the relative angle θ between the flow direction of the fluid and the pressure detector.
FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fluid pressure detector 1a Fluid pressure detector 1b Fluid pressure detector 2 Upper wall 3 Lower wall 4 Left and right closing wall 5 Front and rear walls 6 Pressure outlet 7 Pressure measurement hole 8 Space 10 Casing 11 Rectifier 12 Communication pipe 13 Cover body 14 Screw 15 Sensor socket 16 Hollow part 17 Pressure outlet pipe 18 Average pressure outlet

Claims (5)

[Claims] 1. A rectifier is provided upstream in a casing,
An air volume measurement device provided with a fluid pressure detector on the downstream side, wherein the fluid pressure detector comprises a total pressure measurement detector and a static pressure measurement detector each formed of a hollow body along a flow direction of a fluid. Characterized in that the total pressure measurement hole of the total pressure measurement detector is positioned toward the upstream side of the fluid flow, and the static pressure measurement hole of the static pressure measurement detector is positioned toward the downstream side of the fluid flow. measuring device. 2. The air flow measuring device according to claim 1, wherein the total pressure measurement detector and the static pressure measurement detector are flat, substantially rectangular hollow bodies. 3. The air flow measuring device according to claim 1, wherein the total pressure measurement detector and the static pressure measurement detector are formed in the same shape and the same size, and are connected back to back. 4. The air flow measuring device according to claim 1, wherein the total pressure measurement detector and the static pressure measurement detector are integrally formed with the same shape and the same dimensions. 5. The method according to claim 1, wherein the total pressure measurement detector and the static pressure measurement detector are formed in the same shape and the same size, and are arranged with a small space between them back to back. The air volume measuring device as described.