JPS6331726B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vortex flow meter that detects fluctuating pressure due to Karman vortices using a piezoelectric element.

This type of vortex flowmeter generates a Karman vortex in the fluid passing through a vortex generator, and uses some detection means to detect and measure the pressure change caused by the generation of this Karman vortex, thereby measuring the flow velocity and flow rate of the fluid. are doing.

As this detection means, for example, there is a method in which a displacement detector such as a strain gauge is attached to a diaphragm-like diaphragm and the amount of displacement of this displacement detector is electrically detected and taken out.
Widely known in No. 21501.

However, such conventional vortex flowmeters
Since the displacement detector is provided in a chamber provided within the vortex generator, (i) manufacturing is difficult and inefficient; (ii) The volume in which the displacement detector can operate is narrow because it is inside the vortex generator, and the amount of displacement cannot be large, resulting in poor detection sensitivity. (iii) Since the displacement detector comes into direct contact with the fluid to be measured, there are many practical disadvantages such as rapid damage and aging.

This invention eliminates the above-mentioned drawbacks, and aims to provide a vortex flowmeter with improved Karman vortex detection sensitivity and improved durability.

An embodiment of this invention will be described below with reference to the drawings. 1 is a pipe body (pipe omitted) for the fluid to be measured; 2 is a vortex generating body having an appropriate structure fitted to the pipe body 1; 3
4 is a cut surface formed above the vortex generator 2 of the tube body 1, and 4 is the pressure of the Karman vortex that reaches the inside of the vortex generator 2 without penetrating the tube body 1 or through the cut surface 3. The change detection chambers 5, 5 are pressure communication ports that are open at the top and bottom of the vortex generator 2, as shown in FIG.

6 is a cylindrical body fixed to one end of the vortex generator 2 or tube body 1; 7 is an elastic base material disposed at an axially symmetrical position of this cylindrical body 6; 8 is a base material affixed to the surface of this elastic base material 7. Piezoelectric element, 9 is a filler that also serves as an insulating material, 10
11 is a flange of the cylindrical body 6, and 12 is a conductive wire.

One end 6a of the cylindrical body 6 is formed into a plate shape, and divides the pressure change detection chamber 4 into two. Furthermore, the piezoelectric element 8 may be attached to one or both surfaces of the elastic base material 7. A detector is constructed by fixing the elastic base material 7 to which the piezoelectric element 8 is attached with a filler that also serves as an insulating material. This detector consists of an elastic base material 7
The piezoelectric element 8 may be adhered to the surface of the substrate, covered with ceramic, and fixed with an insulating material such as glass.

In addition, as shown in FIG. 2, the plate-like surface of the other end of the cylindrical body 6 fixed to one end of the vortex generator 2 or the tube body 1 is oriented perpendicularly to the flow, and the vortex generator 2 is The pressure communication ports 5 on the side surfaces may be arranged so as to be located on both sides of the plate-like surface.

The operation of this invention will be explained based on the above configuration.

When the fluid to be measured flowing inside the pipe body 1 passes through the vortex generator 2, Karman vortices are alternately generated on both sides of the vortex generator 2 in accordance with the flow velocity.

This Karman vortex passes through the pressure communication ports 5, 5 as a pressure change and causes a subtle change in the pressure inside the pressure change detection chamber 4.
a changes, and this fluctuation causes the piezoelectric element 8 attached to the surface of the elastic base material 7 arranged at an axially symmetrical position of the cylindrical body 6 to
The piezoelectric element 8 converts a fluctuating pressure signal proportional to the flow rate into an electrical signal. Therefore, this amount of displacement is detected as an electrical amount by the conducting wire 12, and the flow velocity and flow rate of the fluid to be measured can be measured.

Since the lower part 6a of this cylindrical body 6 is fixed vertically within the elongated pressure change detection chamber 4 that reaches above the tube body 1 and the vortex generating body 2, the amount of change in fluctuating pressure due to the vortex can be relatively large. Therefore, the detection sensitivity can be improved, and since the detector 10 is not provided in the lower part 6a of the cylindrical body 6, but is provided in the upper part corresponding to the part other than the pressure change detection chamber 4, it is not in contact with the fluid to be measured. Therefore, it can withstand long-term use and can significantly improve damage and aging.

In the case of the embodiment shown in FIG. 2, the structure is such that it is not easily affected by mechanical vibrations in the piping system, so it has sufficient practicality as an industrial meter.

As mentioned above, the present invention has many features that cannot be obtained with conventional displacement detectors, such as improved Karman vortex detection sensitivity, improved durability, and ease of processing and manufacturing.

[Brief explanation of the drawing]

Figure 1a is a vertical cross-sectional view of the main part of a vortex flow meter showing an embodiment of this invention, Figure 1b is a cross-sectional view taken along the line A--A of the device shown in Figure 1a, and Figure 2a is a cross-sectional view of this invention. FIG. 2b is a sectional view taken along the line BB of the device shown in FIG. 2a, and FIG. 3a is a pressure change detection mechanism of the device shown in FIG. 1a. Fig. 3b is an enlarged longitudinal sectional side view of the one shown in Fig. 3a, Fig. 3c is an enlarged bottom view of the one shown in Fig. 3a, and Fig. 4a is an enlarged longitudinal sectional view of the one shown in Fig. 2a. Fig. 4b is an enlarged longitudinal sectional side view of the pressure change detection mechanism shown in Fig. 4a, and Fig. 4c is an enlarged bottom view of the pressure change detection mechanism shown in Fig. 4a. . 1... Tube body, 2... Vortex generator, 6... Cylindrical body,
5... Pressure communication port, 7... Elastic matrix, 8... Piezoelectric element, 10... Detector.

Claims (1)

[Scope of Claims] 1. A vortex generator disposed opposite to the flow in a pipe through which the fluid to be measured flows is connected to a pressure change detection chamber bored parallel to the axis of the vortex generator. A pressure communication port is bored in the side surface of the vortex generator, a minute gap is maintained in the pressure change detection chamber with the wall surface of the pressure change detection chamber, and a cylindrical body is fixed to one end of the vortex generator or the tubular body. The other end of this cylindrical body is formed into a plate shape to receive fluctuating pressure due to the vortex introduced from the pressure communication port, and this fluctuating pressure is applied to an elastic base material disposed at an axially symmetrical position of the cylindrical body. A piezoelectric element is pasted on the surface of the fluid and is fixed with a filler that also serves as an insulating material.The flow rate and flow rate are measured by converting the fluctuating pressure signal caused by the vortex, which is proportional to the flow rate, into an electrical signal. A vortex flow meter featuring: 2. The vortex flowmeter according to claim 1, wherein the detector is a piezoelectric element adhered to the surface of an elastic base material, covered with ceramic, and fixed with an insulating material such as glass. 3. The plate-shaped surface of the other end of the vortex generator or the cylinder fixed to one end of the tube is oriented perpendicularly to the flow, and the pressure communication ports on the side surfaces of the vortex generator are connected to both sides of the plate-shaped surface, respectively. The vortex flowmeter according to claim 1 or 2, characterized in that the vortex flowmeter is arranged so as to be located on a surface.