JP2001336961A - Vortex flowmeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vortex flowmeter capable of measuring a flow rate of a fluid with good accuracy. SOLUTION: This vortex flowmeter 1 is a pressure detecting type vortex flowmeter for measuring the flow of a fluid F by detecting a pressure change due to a vortex generated in a measuring pipe 2. Wall parts 2e, 2f are parts substantially uniform in thickness between the inner peripheral part of the measuring pipe 2 and the bases 2a, 2b. The wall parts 2e, 2f are plate-like thin parts formed between the inner peripheral surface of the measuring pipe 2 and the bases 2a, 2b, and formed like flat surfaces substantially parallel to the bases 2a, 2b and having no curvature. Accordingly, the areas of the pressure receiving parts of the pressure detecting part 5 4, 5 are increased so that the measurement sensitivity is improved and influence on disturbance such as bubbles can be decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a vortex flowmeter for measuring a flow rate of a fluid.

[0002]

FIG. 4 is a sectional view schematically showing a conventional vortex flowmeter. FIG. 5 is a cross-sectional view showing a state cut along the line VV in FIG. A conventional vortex flowmeter 101 is a device that generates a vortex in a measurement tube 102 through which a fluid F flows, and measures the flow rate of the fluid F. As shown in FIGS. 4 and 5, the vortex flow meter 101 includes a measurement tube 102 and a vortex generator 103.
, Pressure detectors 104 and 105, and holding plate 10
6 is provided.

[0003] The measuring tube 102 is a conduit through which the fluid F flows. For example, a fluid F such as a gas, a liquid, and a vapor passes through the measurement tube 102 in a direction indicated by an arrow in FIG. The measuring tube 102
For example, it is made of a stainless steel tube or the like, and the surface (liquid contact surface) on the side that comes into contact with the fluid F is lined with polyvinyl chloride, polypropylene, a fluororesin, or the like.
On the outer peripheral portion of the measuring tube 102, receiving portions 102c and 102d having bottom surfaces 102a and 102b are formed.
Wall portions 102e and 102f are formed between the inner peripheral portion of the measurement tube 102 and the bottom surfaces 102a and 102b.

The vortex generator 103 is a column that generates a vortex in the measuring tube 102. The vortex generator 103 is a measuring tube 1
02 are fixed at both ends. The shape of the vortex generator 103 is preferably such that the position (separation point) where the Karman vortex is separated and flows alternately is constant, stably generates the vortex in a wide range of flow rate, and the number of Strouhal is small. Shapes (prismatic prisms) with sharp edges are preferred so as to be constant. The cross-sectional shape of the vortex generator 103 is preferably, for example, a trapezoidal shape shown in FIGS.

[0005] The pressure detectors 104 and 105 are provided with a vortex generator 1.
03 is a device that detects a pressure change due to a vortex generated. Each of the pressure detection units 104 and 105 is a pressure sensor having a electromechanical conversion element such as a piezoelectric element. The pressure detecting units 104 and 105 detect an alternating pressure change (alternating pressure difference) generated around the vortex generator 103 by the wall portions 102 e and
Detect through 102f. Pressure detectors 104 and 105
Are arranged symmetrically downstream of the vortex generator 103 when viewed from the radial direction of the measurement tube 2 and output an electric signal corresponding to a distortion (deformation amount) caused by a pressure change. Pressure detector 1
04 and 105 are stored in the storage units 102c and 102d, respectively.

[0006] The pressing plate 106 is
4 and 105 are members that press the pressure detection units 104 and 105 so that they do not fall out of the storage units 102c and 102d. The holding plate 106 includes the pressure detecting units 104 and 10.
The pressure detectors 104 and 105 are connected to the bottom surface 1 such that the lower end surface (detection surface) of the base 5 and the bottom surfaces 102a and 102b are in pressure contact with each other.
02a and 102b. Holding plate 1
Reference numeral 06 is fixed to the outer peripheral portion of the measuring tube 102 by four bolts 106a.

[0007]

FIG. 6 is an enlarged sectional view showing a portion VI in FIG. The pressure detection unit 104 detects a pressure change P due to a vortex generated in the measurement tube 102 via a wall 102e formed between the inner peripheral surface of the measurement tube 102 and the bottom surface 102a. As shown in FIG. 6, since the inner peripheral surface of the measurement tube 102 is a cylindrical surface having a curvature, the thickness of the wall portion 102 e increases as the distance from the vortex generator 103 increases. For this reason, there has been a problem that the measurement sensitivity in a portion away from the vortex generator 103 is reduced.

An object of the present invention is to provide a vortex flowmeter capable of accurately measuring the flow rate of a fluid.

[0009]

The present invention solves the above-mentioned problems by the following means. Note that the description will be given with reference numerals corresponding to the embodiments of the present invention, but the present invention is not limited to this. The invention according to claim 1 is a vortex flowmeter for measuring a flow rate of a fluid (F), comprising: a measurement pipe (2) through which the fluid flows; and a vortex generator (3) that generates a vortex in the measurement pipe. A pressure detecting unit (4, 5) for detecting a pressure change (P) due to a vortex generated by the vortex generator, wherein the measuring tube is in contact with an outer peripheral portion of the measuring tube. (2a, 2b), a wall portion (2) having a substantially uniform thickness between the inner peripheral portion of the measurement tube and the contact portion.
e, 2f). A vortex flowmeter (1) characterized by comprising:

According to a second aspect of the present invention, in the vortex flowmeter according to the first aspect, the contact portion is a bottom surface of a housing portion (2c, 2d) that houses the pressure detecting portion, and the wall portion is It is a vortex flowmeter characterized by being a flat thin portion.

[0011] The invention of claim 3 is claim 1 or claim 2.
The vortex flowmeter according to any one of the first to third aspects, wherein the pressure detection unit is a pair of pressure sensors disposed downstream of the vortex generator.

[0012]

Embodiments of the present invention will be described below in more detail with reference to the drawings. FIG. 1 is a sectional view schematically showing a vortex flowmeter according to an embodiment of the present invention. FIG. 2 is a sectional view showing a state cut along the line II-II in FIG. FIG. 3 is an enlarged sectional view showing a portion III in FIG. Note that the same members as those shown in FIGS. 4 and 5 are denoted by the corresponding reference numerals, and detailed description is omitted.

The vortex flowmeter 1 is a device that generates a vortex in the measurement tube 2 through which the fluid F flows, and measures the flow rate of the fluid F. The vortex flow meter 1 is a pressure detection type vortex flow meter that detects a pressure change P due to a vortex generated in the measurement pipe 2 and measures the flow rate of the fluid F. As shown in FIGS. 1 to 3, the vortex flowmeter 1 includes a measurement pipe 2, a vortex generator 3, pressure detection units 4 and 5,
And a holding plate 6. The inner peripheral portion of the measurement tube 2 is formed in a planar shape in which the vicinity of the fixed end of the vortex generator 3 has no curvature along the flow direction of the fluid F.

The bottom surfaces 2a and 2b are contact portions that come into contact with the lower end surfaces (detection surfaces) of the pressure detection units 4 and 5. Bottom surface 2a, 2
“b” is formed flat so as to make pressure contact with the pressure detecting units 4 and 5 over the entire surface.

The storage sections 2c and 2d are sections for storing the pressure detection sections 4 and 5, respectively. The housing portions 2c and 2d are concave portions (holes) formed on the outer peripheral surface of the measurement tube 2, and have bottom surfaces 2a and 2b.
Having. The housings 2c and 2d detachably house the pressure detectors 4 and 5 so that the pressure detectors 4 and 5 can be replaced without stopping the flow of the fluid F.

The walls 2e and 2f are portions having a substantially uniform thickness between the inner peripheral portion of the measuring tube 2 and the bottom surfaces 2a and 2b. The wall portions 2e and 2f are flat thin portions formed between the inner peripheral surface of the measuring tube 2 and the bottom surfaces 2a and 2b, and the bottom surfaces 2a and 2b
And is formed in a planar shape having no curvature.

Next, the operation of the vortex flowmeter according to the embodiment of the present invention will be described. When the fluid F flows into the measuring pipe 2, the vortex generator 3 emits a vortex, and the pressure around the vortex generator 3 changes alternately (alternating differential pressure), and this pressure change via the walls 2e and 2f. P is transmitted to the pressure detecting units 4 and 5. Since the alternating pressure difference changes every time a vortex is generated, the frequency of the vortex (vortex signal) is detected by counting the differential of the pressure change P, and the flow rate of the fluid F is measured.

The vortex flowmeter according to the embodiment of the present invention includes:
The following effects are obtained. In this embodiment,
Bottom surface 2 of housing sections 2c, 2d housing pressure detecting sections 4, 5
Walls 2 e and 2 f having a substantially uniform thickness are formed between a and 2 b and the inner peripheral portion of the measurement tube 2. For this,
As compared with the conventional vortex flowmeter 101 as shown in FIG. 6, the thickness of the wall portions 2e and 2f in the portion away from the vortex generator 3 is reduced. As a result, since the area of the pressure receiving sections of the pressure detecting sections 4 and 5 is increased, the measurement sensitivity is improved, and the influence on disturbance such as bubbles can be reduced.

The present invention is not limited to the embodiment described above, but can be variously modified or changed.
These are also within the scope of the present invention. For example, in this embodiment, a pair of pressure detection units 4 and 5 are provided downstream of the vortex generator 3.
Although the description has been given by taking the case where the vortex generator 3 is installed as an example, the present invention can also be applied to a vortex flowmeter in which the pressure detectors 4 and 5 are installed near the side surface of the vortex generator 3.

[0020]

As described above, according to the present invention, the contact portion with which the pressure detecting portion comes into contact is provided on the outer peripheral portion of the measuring tube, and the thickness between the inner peripheral portion of the measuring tube and the contact portion is increased. Since a substantially uniform wall is provided, the flow rate can be measured accurately.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing a vortex flowmeter according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a state cut along a line II-II in FIG. 1;

FIG. 3 is an enlarged sectional view showing a portion III in FIG. 2;

FIG. 4 is a cross-sectional view schematically showing a conventional vortex flowmeter.

FIG. 5 is a cross-sectional view showing a state cut along a line VV in FIG. 4;

FIG. 6 is a cross-sectional view showing a VI portion of FIG. 5 in an enlarged manner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vortex flow meter 2 Measuring pipe 2a, 2b Bottom (contact part) 2c, 2d Housing part 2e, 2f Wall part (thin part) 3 Vortex generator 4, 5 Pressure detecting part (pressure sensor) F Fluid P Pressure change

Claims (3)

[Claims] 1. A vortex flowmeter for measuring a flow rate of a fluid, comprising: a measurement pipe through which the fluid flows; a vortex generator for generating a vortex in the measurement pipe; and a pressure change caused by the vortex generated by the vortex generator. And a pressure detecting unit for detecting the thickness of the measuring tube, wherein the measuring tube includes a contact portion with which the pressure detecting unit contacts an outer peripheral portion of the measuring tube, and a thickness between the inner peripheral portion of the measuring tube and the contact portion. Wherein the vortex flowmeter has a substantially uniform wall. 2. The vortex flowmeter according to claim 1, wherein the contact portion is a bottom surface of a storage portion that stores the pressure detection portion, and the wall portion is a flat thin portion. Features vortex flowmeter. 3. The vortex flowmeter according to claim 1, wherein the pressure detector is a pair of pressure sensors disposed downstream of the vortex generator. Flowmeter.