JPH038695B2 - - Google Patents

Description

TECHNICAL FIELD The present invention relates to a vortex flowmeter that utilizes a Karman vortex generated by a vortex generator disposed in a fluid.

PRIOR ART As is well known, when a columnar vortex generator is inserted into a fluid, the flow separates on both sides of the vortex generator, and regular vortices, that is, Karman vortices are alternately generated on the downstream side of the vortex generator. Occur. Since the number of Karman vortices generated is proportional to the fluid or flow rate, the flow rate can be measured by counting the number of Karman vortices. Conventionally, in order to count these Karman vortices, ultrasonic waves were transmitted and received across the Karman vortices and the frequency modulation or phase modulation of the ultrasonic waves was detected. Due to the diffusion, the received signal level is low, and since the flow near the vortex is disturbed, interference with this causes a reduction in S/N, which sometimes causes measurement errors.

Purpose The present invention was made in view of the above-mentioned circumstances, and aims to rectify the flow due to eddy fluctuation differential pressure, eliminate the diffusion of ultrasonic waves, and accurately measure Karman vortices without being affected by disturbances. Regarding the vortex flow meter.

Configuration FIG. 1 is a cross-sectional configuration diagram of main parts for explaining one embodiment of a vortex flowmeter according to the present invention, and FIG.
This is a sectional view taken along the - line in the figure. In the figure, 1 is a flow pipe through which the fluid to be measured flows, 2 is a well-known vortex generator, 3a,
3b is a Karman vortex generated by the vortex generator, 4 is a hollow body provided according to the present invention, and the hollow body 4 intersects with the vortex generator 2 on the downstream side of the vortex generator 2. It is a hollow body arranged in the direction of According to the present invention, the hollow body 4 is disposed to pass through the hole A provided in the wall of the flow pipe 1, and the hole B is provided outside the flow pipe 1. There is. Therefore, according to the present invention, the pressure fluctuation of the fluid to be measured due to the Karman vortex generated by the vortex generator 2 is introduced into the hollow body 4 through the holes A and B, and the pressure fluctuation within the hollow body or the pressure fluctuation is introduced into the hollow body 4 through the holes A and B. Fluid fluctuations caused by this are detected by, for example, the ultrasonic transmitter 5 and the ultrasonic receiver 6, and thereby the flow velocity or flow rate of the fluid to be measured is measured.

As described above, according to the present invention, the vortex pressure introduction hole A is provided in the tube wall of the tube forming the fluid flow path to be measured, and the vortex pressure introduction hole B is provided in the hollow body 4 on the outside of the tube wall. , it is less susceptible to the influence of noise generated within the flow path pipe 1, and the flow due to eddy fluctuation pressure is rectified, so the quality of the detected waveform is good and the eddy pressure introduction hole B can be made larger. Therefore, it is less susceptible to the influence of dust, etc. in the flow path pipe 1, and therefore, the vortex pressure can be detected effectively. In addition, since the pressure introduction hole B can be made perpendicular to the flow path pipe 1 as shown in FIG. 2, it is effective against moisture, dust, etc. in the flow path pipe. Since the holes B are orthogonal, it has advantages such as being effective against disturbance ultrasonic waves.

In FIG. 3, the vortex pressure introduction hole A is separated from the through hole of the hollow body 4. Even with this arrangement, the same effect as the embodiment shown in FIGS. 1 and 2 can be achieved. It's easy to understand.

In FIG. 4, a sound absorbing material 7 is provided on the surface of the member near the vortex pressure introduction hole B to prevent disturbance ultrasonic waves from entering the hollow body and having an adverse effect on the detection signal.

Further, as an embodiment of the present invention, a filter is removably inserted in the vicinity of the vortex pressure introduction hole A, for example, at the position of the sound absorbing material 7 in FIG. This is to prevent dust mixed in the measured fluid from entering the hollow body 4 and disrupting or blocking the flow within the hollow body 4.The filter is a porous metal filter that reduces pressure loss. Small properties are desirable.

Effects As is clear from the above explanation, according to the present invention, the vortex is not affected by disturbances and there is no fear that the vortex pressure introduction hole will be blocked by dust mixed in the fluid to be measured. A flow meter can be provided.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional configuration diagram of main parts for explaining one embodiment of a vortex flowmeter according to the present invention, and FIG.
3 is a cross-sectional view taken along the line 3, FIG. 3 is a diagram with the position of the vortex pressure introduction hole A changed, and FIG. 4 is a configuration diagram in which a sound absorbing material is installed. 1... Channel pipe, 2... Vortex generator, 3a, 3b...
...Karman vortex, 4...Hollow body, 5...Ultrasonic transmitter, 6...Ultrasonic receiver, 7...Sound absorbing material, A, B
...Vortex pressure introduction hole.

Claims (1)

[Scope of Claims] 1. A vortex generator disposed in a tube of a flow path to face the flow, and a wall of the tube in a direction intersecting the vortex generator on the trailing side of the vortex generator. a hollow body having a vortex pressure introduction hole that penetrates through and introduces fluctuating pressure due to the vortex to the outside of the tube wall; and a hole in the tube wall near the hollow body;
It consists of another vortex pressure introduction hole communicating with the vortex pressure introduction hole of the hollow body, and an ultrasonic transmitter/receiver arranged oppositely at both ends of the hollow body, and transmits a vortex signal to the fluid flowing in the hollow body due to the fluctuating pressure. A vortex flow meter characterized by determining fluctuations from changes in the propagation velocity of ultrasonic waves. 2. The vortex flowmeter according to claim 1, wherein a porous body is removably inserted between the vortex pressure introduction ports of each of the hollow bodies. 3. The vortex flow meter according to claim 1 or 2, characterized in that the vortex pressure introduction hole bored in the hollow body is oriented perpendicularly to the flow pipe.