JPS59107208A - Vortex street flowmeter - Google Patents

Abstract

PURPOSE:To prevent the malfunction due to the variance of temperature or the like by using a partitioning plate to detect the variance of pressure due to a Karman's vortex street as a torsional stress of a torque tube. CONSTITUTION:A vortex generating body 2, a torque tube 3b, a torque tube fixing part 3a, a pressure receiving plate 3c, and a distortion sensor 3d are attached to a main body part 1 inserted to a duct. When a fluid to be measured is flowed into the duct, a Karman's vortex street is generated in the downstream side of the vortex generating body 2 to cause a variance of pressure. When this variance of pressure is introduced to two chambers partitioned by the pressure receiving plate 3c from a pressure introducing port 3b, a periodical pressure difference is generated between both faces of the pressure receiving plate 3c, and the torque tube 2b is torsionally oscillated by this pressure difference. This torsional stress is detected by a distortion sensor 3d.

Description

[Detailed description of the invention] The present invention relates to vortex flow needles.

BACKGROUND ART A vortex flow needle is known in which a vortex generator is provided in a pipe through which a fluid to be measured flows, and the Karman vortex generated downstream of the vortex generator is detected by various detectors to measure the flow rate of the fluid.

However, in the case of a vortex flow needle that uses a thermistor as the sensor of the vortex detector, when the flow is stopped, the fluid inside the pipe is affected by sunlight outside the pipe, etc. This causes convection, which causes a temperature change due to elements other than the Karman vortex street, which is detected by the thermistor and causes a "C" malfunction. In addition, pressure sensors, ultrasonic sensors, etc. are used as vortex detectors. The vortex flow meter, which measures the flow rate of fluid by detecting the vibration of the vortex generating body caused by the Karman vortex street, detects the vibration of the pump transmitted through the pipe, the vibration of the damper, etc. There was a problem in that the sensor detected vibration noise such as vibration caused by opening and closing, causing malfunction.

In addition, a vortex flow rate needle using a detector having a movable part such as a cylinder ball has a problem in that it is not suitable for fluids containing particles such as slurry.

As mentioned above, all of the known vortex flow rate needles have their own problems, so in the past, it was necessary to use them appropriately depending on the type of fluid to be measured and the conditions of use.
Even with such consideration, it is still difficult to maintain high reliability of measured values.

The present invention has been made based on the above-mentioned viewpoint, and its purpose is to prevent malfunctioning due to the influence of factors other than Karman vortices, such as changes in temperature or vibrations transmitted through pipes. Vortex flow rate 1 that does not cause any damage and is less likely to cause malfunctions.
11.

The gist of this is that an appropriate space is provided inside the vortex generating body, a torque tube having a mounting section at one end thereof, a pressure receiving plate fixed to the side surface of the torque tube, A vortex detector consisting of a strain sensor for detecting torsional stress of the torque tube provided inside the torque tube is housed, and the space is divided into two wheels by these, and each chamber communicates with the side surface of the vortex generating body. Provide a pressure introduction hole,
The pressure change due to the Karman vortex street generated on the downstream side of the vortex generator is introduced from the pressure introduction hole to the two wheels in the appropriate space, and this pressure difference causes torsional vibration in the torque tube attached to the pressure receiving plate. The object of the present invention is to generate a torsional vibration stress and to detect this torsional vibration stress by a strain sensor provided in the torque tube to measure the flow rate of the fluid.

The details of the configuration of the present invention will be explained below based on the drawings.

FIG. 1 is a longitudinal cross-sectional view showing an embodiment of the vortex flow set according to the present invention, and FIG. m2 is a cross-sectional view along line nn in FIG. 1.
The third figure is a partially cutaway perspective view of the vortex detector.

In FIGS. 1, 2, and 3, 1 is a main body inserted into the Tt path, 2 is a vortex generator, 2a is a void inside the vortex generator 2,
2b is a pressure introduction hole, 3 is a dork tube fixing part 3a,
This is a vortex detector consisting of a torque tube 3b, a pressure receiving plate 3C1 strain sensor 3d, and a sensor base material 3e.

The vortex generator 2 has a substantially triangular prism shape, and its cross section is in the shape of an isosceles triangle with each vertex cut off, as shown in Figure 2, and the upstream side surface of the upper part is perpendicular to the fluid flow direction. It is fixed to the body part 1 with a similar fastener, and an appropriate space is provided inside to accommodate the torque tube 3b and pressure receiving plate 3c.

The receiver JE@3c is a rigid plate-like body, and one long side is fixed to the torque tube 3b, and its upper end faces the torque tube fixing part 3a with a small distance between them. The lower O^ side and the other long side face the inner wall of the appropriate space provided in the vortex generating body 2 (°C) with a minute distance therebetween.

No, the pressure introduction holes 2b are configured to communicate with appropriate cavities 2a of the vortex generator 2 from symmetrical positions on both flow-side sides of the vortex generator 2, and to face the pressure receiving plate 3c. .

The torque tube 3b has its upper ring fixed to the torque tube fixing part 3a, and its sentinel surface and side face face the inner wall of the cavity 2a provided in the vortex generator 2 with a minute distance therebetween.
There is.

Distortion sensor 3dl: Jt-n mother t,! 1. It is fixed at the boundary with the torque tube fixing part 3a inside the torque tube 3b together with the sensor base material 7 at an angle of 45° with the axial direction of the torque tube. .

The reason why the strain sensor 3d is arranged at a fixed angle with respect to the axial direction of the torque tube 3b is to most effectively detect the torsional stress in the torque tube 3b caused by the torsional vibration of the pressure receiving plate 3C.

As shown in Figure 3, the third vortex detector consists of a torque tube fixing part 3a, a torque tube 3b, a pressure receiving part 3c, a strain sensor 3d, and a sensor base material 3e, each of which is constructed independently. , is fixed to the vortex generator 2 with a suitable fastener. With this configuration, the detector can be easily inspected or replaced.

When the fluid to be measured flows in the pipe, a Karman vortex street is generated on the downstream side of the vortex generator 2, and pressure changes occur periodically on both sides of the vortex generator on the downstream side. This pressure change causes the pressure introduction hole 2b
When the vortex generator 2 is introduced into the two wheels partitioned by the pressure receiving plate 3c in the cavity 2a, a pressure difference is generated periodically on both sides of the pressure receiving plate 3c, and this pressure difference causes the partition plate 3c to vibrate. Wake up 1. Since the torque tube 2b torsionally vibrates due to the vibration of -, this torsional stress is detected by a strain sensor 2d installed in the torque tube 3b, and the flow rate of the fluid is measured.

Since the present invention is constructed as above, according to the present invention, the pressure negative due to the Karman vortex street generated on the downstream side of the vortex generator, f
In order to detect the stress as the torque tube stress using a partition plate, temperature changes due to elements other than the Karman vortex street, vibration noise transmitted through the J pipe, etc.
It does not cause malfunctions due to vibrations, and the vortex detector is located in the body, has no moving parts, and is configured to detect torsional stress in the torque tube due to minute torsional vibrations of the partition plate. Therefore, it is possible to provide the vortex flow rate II with fewer failures.

Note that the configuration of the present invention is not limited to the assembled embodiments, and may vary depending on the shape and size of the space inside the vortex generator, the shape and size of the torque tube and the pressure receiving plate, their installation direction and position, and the pressure. The shape, size, number, and position of the introduction holes can be freely changed within the scope of the purpose of the present invention, and the present invention encompasses all of them.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of the vortex flow needle according to the present invention, FIG. 2 is a sectional view taken along the line ■-H in FIG. 1,
M (Figure 3 is a partially cutaway perspective view of the vortex detector.・−−m−・−・−・−−−−−One vortex generator Za−−−−−−−−−−−−−−−・・−・
−・−Vacancy 2h inside the vortex generator・−・・・・−・・・−−
−−−−−−−・−Pressure introduction hole 3−−−−−−−−−
------------One vortex detector 3a-----One--
・−・−１−−・−・−・−Torque cutoff fixing part 3b
−−−−・−・−・−・・・・−Torque tube 3c・−−−1−−−−−−−・・−・−・
-Pressure plate 3d-1...
・-Strain Senna Patent Applicant Oval Equipment Industry Co., Ltd. Agent (7524) Mogami City Abe Figure 2 21) Figure 3

Claims (1)

[Claims] A vortex generator is installed in the pipe through which the fluid to be measured flows, and the Karman vortex generated on the downstream side is detected by a vortex detector installed inside the vortex generator to measure the flow rate of the fluid. The vortex detector includes a torque tube having a portion attached to the vortex generator at one end, a pressure receiving plate fixed to the side of the torque tube, and a strain provided inside the torque tube. The vortex detector is inserted into a space provided inside the vortex generator, one end of which is fixed by a mounting part, and the space is partitioned into two wheels by a torque chinib and a pressure receiving plate. The above-mentioned vortex flowmeter is characterized in that the above-mentioned vortex flowmeter is further provided with pressure introduction holes communicating from the two wheels to the same side of the vortex generating body.