JPH0236093Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention mainly relates to the structure of a static pressure measuring tube in a current meter that measures the flow velocity of air in an air conditioning duct.

[Conventional technology]

Conventional flowmeters usually measure total pressure and static pressure using a pitot tube, and measure the flow rate based on the pressure difference. This Pitot tube is a double tube, with the tip of the inner tube open and facing upwind to measure the total pressure, and the space formed between the outer tube and the inner tube being sealed, and the outer tube Static pressure was measured by drilling a static pressure measurement hole in the side surface that communicated with the space.

In response, a current meter structure as shown in Japanese Patent Application Laid-open No. 59-3315 was proposed, and in this structure,
In the pipe insertion part of the rod-shaped member inserted into the fluid transport pipe in a position perpendicular or almost perpendicular to the streamline,
a first sensor that detects the total pressure as an electrical signal;
A second sensor that detects static pressure as an electric signal is attached, and the detection signals of these two sensors are transmitted from the insertion part into the tube to the outside of the tube via the inside of the rod-shaped member.

[Problem that the invention attempts to solve]

However, in the static pressure measurement with the above conventional structure, the pressure receiving surface of the current transmitter S ₂ as the second sensor for taking out the static pressure is formed of a diaphragm, bellows, etc. When the surface is set to be inclined, turbulence occurs near the pressure-receiving surface, and as a result, it is difficult to take in the dynamic pressure component and measure static pressure with high precision.

The present invention was made in view of the above-mentioned conventional problems, and its purpose is to form a large-diameter tube between the ends of the tube body, which has an end facing the upstream side of the air flow, and a tube head. A space is formed extending to the end of the tube in communication with the annular slit, and this space and the inside of the tube are connected by a communication hole provided at the end of the tube. We provide a static pressure measurement tube for a current meter that can measure static pressure with high accuracy without incorporating dynamic pressure components even when the static pressure measurement tube is set at an angle with respect to the flow velocity direction by communicating with the current flowmeter. It's about doing.

[Means for solving problems]

In order to achieve the above object, the present invention provides a static pressure measuring tube for a current meter that measures the flow velocity of air in a ventilation duct of a structure, and includes a pressure gauge 1 for measuring static pressure.
4, a tube 3 having an end facing the upstream side of the air flow, a large-diameter tube 2 glued near the end of this tube 3, and the entire end of the tube 3. a pipe head 6 which is formed to cover the pipe and whose end face is close to the end face of the large diameter pipe 2 and is provided so as to form an annular slit 7 between the pipe head 6 and the end face of the large diameter pipe 2; A space 8 is provided between the outer circumferential edge of the tube body 3 and the inner wall of the tube head 6, and the space 8 communicates with the annular slit 7 and extends toward the outermost end of the tube body 3. 8 and the inside of the tube body 3 are constituted by a static pressure measuring tube 1 of a current meter, which communicates with each other through a communication hole 5 provided at the extreme end of the tube body 3.

[Effect]

In the present invention, the static pressure measuring tube 1 is installed approximately in the windward direction, and air flows along the outer periphery of the tube head 6 provided at the most upstream end of the tube body 3 of the static pressure measuring tube 1. The flow does not enter through the annular slit 7, but merely exerts static pressure within the space 8.
Therefore, the static pressure of the air flow in the duct acts on the space 8 formed between the tube body 3 and the inner wall of the tube head 6 via the annular slit 7, thereby causing the communication hole 5 to be closed. The pressure inside the measuring tube 10 is measured through the pressure gauge 1.
4, it is measured as static pressure.

〔Example〕

1 to 4 mainly explain the static pressure measuring tube of the current meter according to the embodiment of the present invention,
In FIG. 2, a long rectangular measurement tube 10 whose longitudinal direction is substantially perpendicular to the air flow direction is arranged, and has an end portion facing upstream of the air flow from near the center of the measurement tube 10. A hollow cylindrical tube body 3 is connected to the measuring tube 10 in communication. This pipe body 3
A large-diameter tube 2 having a larger diameter than the tube 3 is provided near the upstream end of the tube 3 by forming a bulge or by fitting a separate tube.

Further, a tube head 6 is formed to cover the entire upstream end of the tube body 3.

The pipe head 6 is formed into a sharp point that tapers toward the upstream side, and is fitted from the outside by, for example, a cap structure. The downstream end surface of the tube head 6 is close to the upstream end surface of the large diameter tube 2 so as to face it,
An annular slit 7 is formed between the two at the periphery of the tube body 3.

What is characteristic about this invention is the above-mentioned slit 7.
A space communicating with the pipe body is formed between the outer peripheral wall of the pipe body and the inner peripheral wall of the pipe head 6 so as to extend toward the upstream side of the flow, and this space and the inside of the pipe body are provided at the endmost side of the pipe body. This is because the communication holes were made to communicate with each other.

That is, a space 8 is provided between the outer circumferential edge of the tube body 3 and the inner wall of the tube head 6, communicating with the annular slit 7 and extending toward the most end side (flow upstream side) of the tube body 3. ing. Furthermore, this space 8 and the inside of the tubular body 3 are communicated through a communication hole 5 provided at the endmost side (flow upstream side) of the tubular body 3. In addition, 4 is tube body 3
This is a hollow portion provided at the outer peripheral edge of the outermost end of the tube body 3 to connect the space 8 and the inside of the tube body 3 in an intermediate manner.

Here, the air flow flowing from the most end side (flow upstream side) of the tube body 3 acts on the slit hole of the annular slit 7, and from this, the space 8, the hollow part 4, and the communication hole 5 communicate with each other. The pressure exerted within the tube body 3 becomes a static pressure value.

In the figure, 13 and 13' are air pipes for pressure measurement, and 14
is a pressure gauge for measuring static pressure, 10' is a measuring tube for measuring total pressure,
11 is a total pressure measuring hole provided in the measuring tube 10', 12 is a horizontal guide cylinder, and 14' is a pressure gauge for measuring the total pressure.

In this embodiment, the airflow flowing from the end side of the tube body 3 flows along the downstream side from the sharp point of the tube head 6 and along the outer periphery of the tube head 6, and flows through the annular slit 7. Static pressure in the airflow in the duct acts on the inside of the tube body 3 from inside through the space 8, the hollow part 4, and the communication hole 5, and as a result, the static pressure of the measurement tube 10 with which the static pressure measurement tube 1 is communicated acts. The internal pressure becomes equal to the static pressure within the duct. In this way, since the space 8 extends toward the end of the pipe body 3 (upstream side of the flow), that is, in the direction opposite to the flow from upstream, the annular slit 7 simply releases the static pressure of the air flow. It will work.

Here, even if the static pressure measuring tube 1 is arranged at an angle in the duct during flow velocity measurement work, a dynamic pressure component does not act in the space 8, and the static pressure can be measured with high accuracy. becomes.

Incidentally, the total pressure is determined by introducing the air flow in the duct through the tip opening of the horizontal guide tube 12, once stagnation, and after averaging the pressure, it acts on the measurement tube 10' through the total pressure measurement hole 11, The pressure inside the measuring tube 10' is equal to the total pressure. In this way, the pressure in the measuring tubes 10, 10' is made equal to the static pressure and the total pressure, respectively, and this pressure is
The pressure is then measured using the pressure gauges 14 and 14'.

FIG. 4 is a graph showing the gap between the flow velocity direction in the duct and the direction of the static pressure measuring tube 1 based on the above embodiment, that is, the relationship between the measured value and the inclination angle θ. The line indicated by "△" indicates the measured value using the conventional pitot tube, and the line indicated by "△" indicates the measured value using the static pressure measuring tube 1 according to the embodiment.

As shown in this experimental result, in the case of a conventional Pitot tube, the inclination angle θ is - when the pressure value is within ±5%.
While accuracy of ±5% is maintained in an angle range of about 17° and 13°, that is, 30°, in this example, the inclination angle θ is about -44° and 54°, that is, an angular range of 100°. In±
Can maintain an accuracy of 5%, static pressure measuring tube 1
It can be seen that stable and highly accurate static pressure measurements can be obtained without worrying about the slope of the air flow.

Although this embodiment shows a case where the communication hole 5 is provided on the side surface of the tube body 3, the communication hole 5 is not limited to this, and for example, as shown in FIG. It's okay.

[Effect of idea]

As explained above, according to the static pressure measuring tube of the current meter according to the present invention, a large diameter tube is formed on the end side of the tube body having an end facing the upstream side of the air flow, and a tube head. forming an annular slit, communicating with the annular slit and extending a space to the outermost end of the tube body;
By communicating this space with the inside of the tube through a communication hole provided at the end of the tube, dynamic pressure components can be taken in even when the static pressure measurement tube is set at an angle with respect to the flow velocity direction. This makes it possible to measure static pressure with high precision without any problems.

[Brief explanation of the drawing]

FIG. 1 is an explanatory cross-sectional view of the main parts showing an embodiment of the static pressure measuring tube of the current meter according to the present invention, FIG. 2 is an overall schematic perspective view of the current meter using the same static pressure measuring tube, and FIG. The figure is an enlarged cross-sectional view of the main part of the current meter, Figure 4 is a graph showing the relationship between the tilt angle and the static pressure measurement value for air flow in this embodiment, and Figure 5 is the static pressure measuring tube according to the present invention. FIG. 4 is a cross-sectional explanatory diagram of main parts showing another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Static pressure measuring tube, 2... Large diameter tube, 3... Tube body, 4... Hollow part, 5... Communication hole, 6... Tube head, 7... Annular slit, 8... Space .

Claims (1)

[Scope of Claim for Utility Model Registration] A static pressure measuring tube for a current meter that measures the flow velocity of air in a ventilation duct of a structure, which is connected to a pressure gauge for static pressure measurement and faces the upstream side of the air flow. a tube body having an end; a large-diameter tube fitted near the end of the tube; and a large-diameter tube formed to cover the entire extreme end of the tube, the end surface of which is an end surface of the large-diameter tube. and a tube head provided so as to form an annular slit between the tube body and the end surface of the large diameter tube, the tube head being provided so as to form an annular slit between the tube body and the end surface of the tube head, and the tube head provided between the outer circumferential edge of the tube body and the inner wall of the tube head. It has a space that communicates with the slit and extends to the endmost side of the tube, and further, this space and the inside of the tube communicate with each other through a communication hole provided at the endmost side of the tube. A static pressure measuring tube for a current meter.