JP2001336960A - Vortex flowmeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vortex flowmeter capable of measuring a flow with good accuracy. SOLUTION: A stress transmitting part 6 is a member for absorbing an inclination of a stress detecting part 5 relative to a stress working part 4 and transmitting torsional stress working on the stress working part 4 to the stress detecting part 5. The stress transmitting part 6 is a member for absorbing stress except the torsional stress working on the stress working part 4. The stress transmitting part 6 is a flexible elastic member having high torsional rigidity and low bending rigidity. The stress transmitting part 6 has both longitudinal end parts clamped between the stress working part 4 and the stress detecting part 5, and torsional stress of the stress working part 4 is transmitted to the stress detecting part 5 through a close contact part among them. Accordingly, even if the parallelism between the stress working part 4 and the stress detecting part 5 is insufficient, such inclination can be absorbed by the stress transmitting part 6 and pressurizing force produced between them can be stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, a measurement tube through which a fluid flows, a vortex generator for generating a vortex in the measurement tube, a stress acting portion on which a stress generated by the vortex generated by the vortex generator acts, There is known a vortex flowmeter including a stress detecting unit for detecting a stress acting on the unit. Conventional vortex flowmeters include a method of detecting torque by a stress detection unit and a method of detecting bending.The method of detecting torque is less susceptible to piping vibration than the method of detecting bending. There is an advantage. In the conventional vortex flowmeter, it is necessary to make the stress detection unit detachable from the stress application unit (Online Sensor Replaceable) without stopping the flow of the fluid in the measurement tube. For this reason, the stress detecting section cannot be fixed to the stress acting section by welding or bonding, and the stress detecting section is pressed against the stress acting section, and the friction force is transmitted from the stress acting section to the stress detecting section by surface contact. I was

[0003]

FIG. 4 is a sectional view showing a vortex flowmeter (Comparative Example 1), and FIG. 4B is a sectional view of FIG.
FIG. 4 is a cross-sectional view showing a state cut along line IV-IVB of FIG. FIG.
The vortex flowmeter 101 shown in FIG.
And a vortex generator 103 having a trapezoidal cross-sectional shape, and integrally formed on the upper part of the vortex generator 103,
4a having a stress acting portion 104a and a housing portion 104a
And a stress detection unit (torque sensor) 105 having a projection 105a pressed against the bottom surface 104b of the.

FIG. 5 is a cross-sectional view showing a vortex flowmeter (Comparative Example 2), and FIG. 5B is a cross-sectional view taken along line V-VB of FIG. 5A. Vortex flow meter 201 shown in FIG.
Is a measuring tube 202 through which the fluid F flows, a vortex generator 203 having a trapezoidal cross section, a vane (pressure receiving plate) 203a disposed downstream of the vortex generator 203, and a vane 203a
A stress acting portion 204 integrally formed on the upper portion of the housing portion and having a housing portion (POT) 204a; and a stress detecting portion (torque sensor) 205 having a projection portion 205a pressed against a bottom surface 204b of the housing portion 204a. .

FIG. 6 is a sectional view showing a state in which a stress detecting section is fixed to a stress acting section of a vortex flow meter (Comparative Examples 1 and 2). In the vortex flow meters 101 and 201 shown in FIGS. 4 and 5,
To transmit the torsional stress (torque) acting on the stress acting portions 104 and 204 to the stress detecting portions 105 and 205 without loss, the stress detecting portions 105 and 205 are connected to the bottom surfaces 104 b and 20.
It is necessary to apply a considerable load to 4b and press it.

FIG. 7 is a sectional view showing a vortex flowmeter (Comparative Example 3). The vortex flow meter 301 shown in FIG.
A stress transmission section (torque transmission pin) 309a, 309b for transmitting a torsional stress from 04 to the stress detection section 305 is provided between the stress application section 304 and the stress detection section 305. However, in such a vortex flow meter 301, the holes 304e and 304f formed in the bottom surface 304b and the torque transmission pin 309
a, 309b, there is a gap (clearance)
The torsional stress cannot be transmitted from the stress application section 304 to the stress detection section 305, and the detection sensitivity may be reduced. For this reason, in order to transmit a small torque fluctuation, it is necessary to press-fit the torque transmission pins 309a and 309b into the holes 304e and 304f by applying a certain amount of load.

However, the vortex flowmeter 10 shown in FIGS.
1, 201, 301, the stress acting portions 104, 204,
There is a possibility that bending stress other than torsional stress and the like is transmitted from 304 to the stress detection units 105, 205, and 305. For this reason, vibrations other than in the torsional direction are generated by the stress detection unit 105,
205 and 305 may detect and output. Also,
In the vortex flowmeters 101 and 201 shown in FIGS. 4 to 6, if the parallelism between the stress detection units 105 and 205 and the bottom surfaces 104b and 204b is insufficient, the depths of the storage units 104a and 204a and the projections 105a and 205a. The difference with the length of the length (tightening margin) becomes uneven. As a result, torque is not transmitted over the entire surface of the stress detection units 105 and 205 and the bottom surfaces 104b and 204b, and there is a possibility that these rotation axes are shifted to cause noise.

FIG. 8 is a sectional view showing a vortex flow meter (Comparative Example 4). The vortex flowmeter 401 shown in FIG.
04 transmits only torsional stress to the stress detector 405,
A stress absorbing section 409 for absorbing stress other than torsional stress is provided between the stress applying section 404 and the stress detecting section 405. For this purpose, the vortex flow meter 401 is
The anti-vibration performance can be further improved as compared with 01 and 301. As shown in FIG. 8, the stress absorbing portion 409 includes a bellows type coupling having high torsional rigidity and low bending rigidity, a leaf spring type coupling, a slit type coupling, a diaphragm type coupling, a diaphragm type coupling, and an Oldham type, not shown. Couplings, cross joint couplings, etc.

However, bellows type couplings, leaf spring type couplings, slit type couplings and diaphragm type couplings have low rigidity in the axial direction (longitudinal direction) where a load is applied. Is difficult to press fit. On the other hand, in the Oldham type coupling and the cruciform joint type coupling, since the rigidity in the axial direction to which a load is applied is strong, it is possible to apply a surface pressure or press-fit a pin. However, these couplings have a gap at a connection portion with a slider or a pin due to the structure, and it is difficult to transmit a minute torque fluctuation.

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

[0011]

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 stress acting portion (4) on which a stress generated by the vortex generated by the vortex generator acts; a stress detecting portion (5) for detecting a torsional stress among the stresses acting on the stress acting portion; A vortex flowmeter including a stress transmitting section (6) for absorbing a tilt of the stress detecting section and transmitting a torsional stress acting on the stress applying section to the stress detecting section.

According to a second aspect of the present invention, in the vortex flowmeter according to the first aspect, the stress acting portion has a bottom surface (4b) for pressing the stress transmitting portion between the stress acting portion and the stress detecting portion. The vortex flowmeter according to claim 1, further comprising a housing section (4a) for housing the stress detection section such that the stress detection section is detachable from the outside of the measurement tube.

[0013] The invention of claim 3 is claim 1 or claim 2.
The vortex flowmeter according to any one of claims 1 to 3, wherein the stress transmission unit absorbs a stress other than a torsional stress acting on the stress detection unit.

According to a fourth aspect of the present invention, there is provided the first to third aspects.
In the vortex flowmeter according to any one of the above, the stress transmitting portion is a flexible elastic member (6) having a high torsional rigidity and a low bending rigidity, and the flexible elastic member is configured to perform the stress action. Between both ends in the length direction (6)
f, 6g) are sandwiched.

According to a fifth aspect of the present invention, in the vortex flowmeter according to the fourth aspect, the flexible elastic member includes a shaft portion (6a) formed at a central portion of the flexible elastic member. Slit portions (6b, 6) formed on the outer peripheral surface of the flexible elastic member
c, 6d, 6e).

[0016]

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 an exploded state of the vortex flowmeter according to the embodiment of the present invention. The vortex flowmeter 1 is a device that generates a vortex in the measurement pipe 2 through which the fluid F flows, and measures the flow rate of the fluid F. The vortex flowmeter 1 is shown in FIGS.
As shown in (1), a measuring tube 2, a vortex generator 3, a stress acting section 4, a stress detecting section 5, and a stress transmitting section 6 are provided.

The measuring pipe 2 is a pipe through which the fluid F flows.
For example, a fluid F such as a gas, a liquid,
Passes. The measuring tube 2 is made of, for example, 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, fluororesin, or the like. The measuring tube 2 has a mounting hole 2a formed on the inner peripheral surface thereof, and a through hole 2b penetrating the measuring tube 2 at a position facing the mounting hole 2a.

The vortex generator 3 is a column that generates a vortex in the measuring tube 2. The vortex generator 3 has a lower end fixed to the mounting hole 2 a, an upper end fixed to the through hole 2 b via the stress applying section 4, and both ends fixed in the measuring tube 2. The shape of the vortex generator 3 is preferably such that the position (separation point) where the Karman vortices are separated and flows alternately is constant, the vortices are generated stably over a wide range of flow rate, and the number of Strouhals is reduced. Shapes (prismatic prisms) with sharp edges are preferred so as to be constant. The cross-sectional shape of the vortex generator is, for example, as shown in FIG.
In addition to the trapezoids shown in the above, a triangle, a quadrangle, a T-shape which is a modification thereof, or the like is preferable. A force (lift) acts on the vortex generator 3 alternately in a direction perpendicular to the flow due to the generation and discharge of the vortex.

The stress acting portion 4 is a member on which the stress generated by the vortex generated by the vortex generator 3 acts. The stress acting portion 4 closes the through hole 2b so that the stress detecting portion 5 and the stress transmitting portion 6 can be exchanged without stopping the flow of the fluid F.
To prevent leakage. As shown in FIG. 2, the stress applying section 4 includes a housing section 4a, a bottom face 4b, and a flange section 4c. In the first embodiment, the stress application section 4 is formed integrally on the upper part of the vortex generator 3. When a lift is applied to the vortex generator 3, a bending stress or the like acts on the stress acting portion 4, and when a torque due to the lift is applied around the axis of the vortex generator 3, a torsional stress or the like acts.

The accommodating section 4a is a section for accommodating the stress detecting section 5 so that the stress detecting section 5 can be attached to and detached from the outside of the measuring tube 2. The housing part 4a is a thin cylindrical part inserted into the through hole 2b. The bottom surface 4b is a pressing surface that presses the stress transmitting unit 6 with the stress detecting unit 5. The bottom surface 4b is formed integrally with the housing portion 4a. The flange portion 4c is a fixing portion that fixes the housing portion 4a to the measurement tube 2. The flange part 4c is formed integrally with the housing part 4a,
Is fixed to the outer peripheral surface by welding.

The stress detecting section 5 is a member for detecting a torsional stress among the stresses acting on the stress applying section 4. The stress detection unit 5 is, for example, a torque sensor having a electromechanical transducer such as a piezoelectric element. The stress detection unit 5 absorbs shear stress by arranging the piezoelectric elements symmetrically, and outputs only an electric signal corresponding to distortion (amount of deformation) due to torsional stress. The stress detector 5 includes a columnar projection 5a housed in the housing 4a, and a joint 5b that joins the flange 4c.

FIG. 3 is an overall view of a stress transmitting portion in the vortex flowmeter according to the embodiment of the present invention, FIG. 3 (A) is a front view, FIG. 3 (B) is a side view, and FIG. FIG. 3 (C) is a plan view. The stress transmission unit 6 absorbs the inclination of the stress detection unit 5 with respect to the stress application unit 4, transmits the torsional stress acting on the stress application unit 4 to the stress detection unit 5, and transmits the torsional stress other than the torsional stress applied to the stress application unit 4. Is a member that absorbs the stress of The stress transmitting portion 6 is a flexible elastic member having high torsional rigidity and low bending rigidity. As shown in FIG. 1 and FIG. 2, the stress transmitting section 6 has both ends in the length direction sandwiched between the stress applying section 4 and the stress detecting section 5, and the stress is transmitted through a portion in close contact with these sections. The torque (torsional stress) on the action section 4 side is transmitted to the stress detection section 5 side. As shown in FIG. 3, the stress transmitting portion 6 includes a shaft portion 6a, slit portions 6b, 6c,
6d and 6e, and close contact surfaces 6f and 6g.

The shaft 6a is a portion formed at the center of the flexible elastic member. The shaft portion 6a is a central shaft portion left unprocessed when a solid round rod-shaped (columnar) flexible elastic member is slit. The shaft portion 6a has sufficient rigidity against a load in the axial direction (length direction) and torsion around the axis.

The slits 6b, 6c, 6d, 6e are cutouts formed on the outer peripheral surface of the flexible elastic member. The slits 6b and 6c are formed in a direction opposite to each other in the same plane with respect to the flexible elastic member, and the slits 6d and 6e are parallel to the plane on which the slits 6b and 6c are formed. The slits 6b and 6c are formed so as to be shifted from each other by approximately 90 degrees in a plane and to face each other. The slits 6b, 6c, 6d, 6e are formed in a plurality of steps (two steps) on the outer peripheral surface of the flexible elastic member from different directions, and the slits 6b, 6c are formed in the upper step.
The slits 6d and 6e are formed in the lower stage.

The contact surface 6f is a flat portion that is in close contact with the projection 5a, and the contact surface 6g is a flat portion that is in close contact with the bottom surface 4b. The contact surfaces 6f and 6g are formed on both end surfaces of the flexible expansion and contraction member, and are brought into close contact with the projections 5a and the bottom surface 4b under pressure to make the bottom surface 4b and the projections 5a substantially parallel to each other. To absorb the inclination of the projection 5a.

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 measurement tube 2, the vortex generator 3 emits a vortex, and a force in a direction perpendicular to the flow of the fluid F acts on the vortex generator 3 alternately. When the vortex generator 3 is bent right and left and twisted around the axis by this force, a bending stress, a torsional stress, and the like are applied to the stress acting portion 4. When torsional stress acts on the stress acting portion 4,
The stress transmitting section 6 transmits the torsional stress from the stress acting section 4 to the stress detecting section 5. Since the direction of the torsional stress is reversed each time a vortex is generated, the frequency of the vortex (vortex signal) is detected by the stress detection unit 5 counting the direction of the torsional stress (torque signal). Is measured.

The vortex flowmeter according to the embodiment of the present invention includes:
The following effects are obtained. (1) In this embodiment, the inclination of the stress detection unit 5 with respect to the stress application unit 4 is absorbed by the stress transmission unit 6. For this reason, even if the degree of parallelism between the projection 5a and the bottom surface 4b is insufficient, these inclinations can be absorbed by the stress transmitting portion 6 and the additional force generated between the projection 5a and the bottom surface 4b. The pressure can be stabilized. As a result, vibration and noise generated due to the inclination between the protrusion 5a and the bottom surface 4b can be reduced. In addition, since the relationship between the interference and the compressive force becomes gentler than in the case where the stress detecting section 5 is directly pressed against the stress applying section 4, the depth of the accommodation section 4a and the dimensional tolerance of the entire length of the projection section 4a are strict. There is no need to perform this, and processing becomes easier.

(2) In this embodiment, the stress detector 5
This stress detecting section 5 is detachable from the outside of the measuring tube 2.
Is accommodated in the accommodation section 4a. Therefore, the stress detection unit 5 can be replaced without stopping the flow of the fluid F.

(3) In this embodiment, the stress transmitting section 6
Is a flexible elastic member having high torsional rigidity and low bending rigidity. For this reason, it is possible to transmit the torsional stress acting on the stress application section 4 to the stress detection section 5 and to absorb bending stress and shear stress other than the torsional stress. As a result, bending stress and the like transmitted to the stress detection unit 5 are reduced, and the S / N ratio with respect to vibration can be improved.

(4) In this embodiment, the shaft 6a is formed at the center of the flexible elastic member. For this,
The load applied in the axial direction of the stress transmitting portion 6 can be sufficiently elastically supported. The contact surfaces 6f, 6g and the bottom surface 4b
In addition, the pressure at the contact surface with the projection 5a is sufficiently high, and the torsional rigidity of the stress transmission unit 6 is increased, so that torque can be transmitted from the stress application unit 4 to the stress detection unit 5 without loss. Further, the excessive compressive stress applied to the stress detecting section 5 can be easily absorbed by the stress transmitting section 6.

(5) In this embodiment, slit portions 6b, 6c, 6d, 6e are formed on the outer peripheral surface of the flexible elastic member. As a result, the bending rigidity of the stress transmitting portion 6 becomes weak, so that stress other than torsional stress can be absorbed.

The present invention is not limited to the embodiments described above, but various modifications or changes are possible as described below, and these are also within the scope of the present invention. (1) In this embodiment, the vortex flowmeter in which the stress acting part 4 is integrally formed on the upper part of the vortex generator 3 has been described as an example, but it is arranged downstream of the vortex generator 3 as shown in FIG. The present invention can also be applied to an eddy flow meter in which a stress acting portion is integrally formed on the upper part of the vane (pressure receiving plate).

(2) In this embodiment, the case where the slit is formed in the flexible elastic member in two steps has been described as an example. However, the number of steps of the slit processing, the angle at which the slit is formed, and the like are limited to this. It is not a thing and can be set arbitrarily.

[0034]

As described above, according to the present invention, the inclination is absorbed by the close contact between the stress acting portion and the stress detecting portion, and the torsional stress acting on the stress acting portion is transmitted to the stress detecting portion. Since the transmission is performed by the unit, the flow rate can be accurately measured.

[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 an exploded state of the vortex flowmeter according to the embodiment of the present invention.

FIG. 3 is an overall view of a stress transmission unit in the vortex flowmeter according to the embodiment of the present invention, where (A) is a front view,
(B) is a side view, and (C) is a plan view.

FIG. 4 is a sectional view showing a vortex flowmeter (Comparative Example 1);
(B) is a cross-sectional view showing a state cut along the line IV-IVB in (A).

FIG. 5 is a sectional view showing a vortex flowmeter (Comparative Example 2);
(B) is a sectional view showing a state cut along the line V-VB of (A).

FIG. 6 is a cross-sectional view showing a state in which a stress detecting section is fixed to a stress acting section of a vortex flow meter (Comparative Examples 1 and 2).

FIG. 7 is a sectional view showing a vortex flowmeter (Comparative Example 3).

FIG. 8 is a sectional view showing a vortex flowmeter (Comparative Example 4).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vortex flow meter 2 Measuring pipe 3 Vortex generator 4 Stress acting part 4a Housing part 4b Bottom surface 5 Stress detecting part 6 Stress transmitting part 6a Shaft part 6b, 6c, 6d, 6e Slit part F Fluid

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Tetsuo Ando 2-9-132 Nakamachi, Musashino City, Tokyo Inside Yokogawa Electric Corporation

Claims (5)

[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 stress generated by the vortex generated by the vortex generator. Acting on the stress acting portion, a stress detecting portion detecting a torsional stress among stresses acting on the stress acting portion, absorbing a tilt of the stress detecting portion with respect to the stress acting portion, and acting on the stress acting portion. And a stress transmission unit that transmits torsional stress to the stress detection unit. 2. The vortex flowmeter according to claim 1, wherein the stress acting portion has a bottom surface that presses the stress transmitting portion between the stress acting portion and the stress detecting portion, and the stress detecting portion includes the measuring pipe. A vortex flowmeter, comprising: a housing portion for housing the stress detection unit so as to be detachable from the outside of the vortex flowmeter. 3. The vortex flowmeter according to claim 1, wherein the stress transmission unit absorbs a stress other than a torsional stress acting on the stress detection unit. . 4. One of claims 1 to 3
In the vortex flowmeter according to the item, the stress transmitting portion is a flexible elastic member having a high torsional rigidity and a low bending rigidity, and the flexible elastic member is formed of the stress acting portion and the stress detecting portion. A vortex flowmeter, characterized in that both lengthwise ends are sandwiched between the vortex flowmeters. 5. The vortex flowmeter according to claim 4, wherein the flexible elastic member includes a shaft formed at a central portion of the flexible elastic member, and an outer peripheral surface of the flexible elastic member. And a slit formed in the vortex flowmeter.