JP3046363B2 - Sensor for Karman vortex flow meter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor for a Karman vortex flowmeter, and more particularly, to a Karman vortex flowmeter which is inserted into a vortex generator and is detachably mounted on a vibrating tube responsive to a Karman vortex. Related to sensors.

[0002]

2. Description of the Related Art As is well known, a Karman vortex flowmeter (hereinafter simply referred to as a vortex flowmeter) is used in a Reynolds number range in which a Strouhal number, which is a proportional constant between a flow rate and a generated Karman vortex frequency, is constant in a flow tube. This is a simple flow meter. It is no exaggeration to say that the vortex flow meter is composed of a vortex generator and a sensor for detecting the vortex generated from the vortex generator.

There are various types of sensors for detecting a vortex, but a pressure detection method for detecting a fluctuating pressure generated due to the generation of a vortex is a typical vortex detection method. The pressure detection method can also be classified into an integral detection type in which a pressure sensor responding to vortex fluctuation pressure is mounted on the vortex generator itself, and a separate type provided separately from the vortex generator on the downstream side.

[0004] The integral detection type can be reduced in shape, but the vortex generator is determined according to the flow rate range measured by the flow meter. That is, the vortex generator has a length corresponding to the diameter of the flow tube corresponding to the flow rate, and the vortex detector is fixed to the vortex generator, which is inefficient in manufacturing and often inconvenient for maintenance and inspection.

In order to solve the above-mentioned problem, the present applicant has previously proposed a vortex flowmeter in which a vortex sensor is attached and detached using the same vortex sensor regardless of the size of the vortex generator.

Japanese Patent Publication No. 31726/1988 relates to the vortex flowmeter according to the present invention. FIG. 3 (a),
(B) is a structural view of the above-mentioned conventional vortex flowmeter, where (a) is a cross-sectional view as viewed from a flowing water direction, and (b) is A- of FIG.
It is an arrow A view. In the figure, 31 is a flow tube, 32 is a vortex generator, 33 is a mounting surface, 34 is a long hole, 35 and 35 are differential pressure introducing holes, 36 is a cylinder, 36a is a pressure receiving plate, 37 is an elastic base material,
38 is a piezoelectric element, 39 is a filler, 40 is a vibration tube, 41 is a mounting flange, and 42 is an output terminal.

[0007] Vortex flowmeter illustrated, has a vortex flowmeter body which is integrally formed by fixing both ends of the vortex generator 3 2 in the flow tube 31 to the fluid to be measured flows, both side surfaces of the vortex generator 32 A pair of differential pressure introducing holes 35, 35 is drilled, and a long hole 34 communicates with the differential pressure introducing holes 35, 35, and the long hole 34 penetrates the pipe wall of the flow tube 31. Flow tube 3 around slot 34
A mounting surface 33 is formed on an outer wall of the vibration tube 1, and a vibration tube 40 having a mounting flange 41 is cantilevered on the mounting surface 33.

The vibrating tube 40 has a bottomed cylindrical body 36, and a pressure receiving plate 36a is provided at an end of the cylindrical body 36. An elastic base material 37 having a piezoelectric element 38 adhered to both sides thereof is inserted on the inner shaft of the cylindrical body 36, and is integrally fixed to the cylindrical body 36 by a filler 39 such as glass.

When the fluid to be measured flows in a direction perpendicular to the plane of the drawing, a vortex is generated downstream of the vortex generator 32, causing pressure fluctuations. The pressure fluctuations are longer than the differential pressure introduction holes 35, 35. 34, and drives the pressure receiving plate 36a in the horizontal direction on the paper. This pressure vibration is transmitted to the piezoelectric element 38 in the cantilevered vibration tube 40 and outputs from the terminal 42 a vortex signal corresponding to the vortex pressure fluctuation.

In the above-mentioned conventional vortex flow meter, the same vortex flow meter is formed separately and the size of the vortex generator is different.
The vibration tube 40 is used by being inserted into the long hole 3 4 in the vortex generator 32 is used as a common, although production can provide streamlined inexpensive vortex flowmeters, contrary there is the following problem .

(1) Since the interior of the vibrating tube 40 is filled with glass at a high temperature, there is a problem in the corrosion resistance of the vibrating tube 40 and the strength is deteriorated. (2) In glass sealing, it takes time to remove internal strain and eliminate the incorporation of air bubbles, so that it is difficult to make the glass. (3) When exposed to a fluid, when a high-temperature fluid flows, the insulation resistance is reduced due to the physical properties of the filled glass. (4) It takes time to dry the sensor. (5) Since the fluid to be measured is ejected through the pressure introducing hole 35 and the long hole 34, the sensor cannot be replaced during operation.

[0012]

A Karman vortex flowmeter according to the present invention has been made in view of the above-mentioned problems, and enables a sensor to be replaced even during operation, and has excellent corrosion resistance and is easy to manufacture. It is intended to provide a sensor.

[0013]

To achieve the above object, the present invention provides (1)
Integrally formed flow tube and the vortex shedder, cantilever the body and, said flow tube wall is inserted into the long hole with a long hole communicating with the pair of differential pressure introducing hole opened on both sides of the vortex shedder It comprises a hollow vibration tube with a bottom that is supported, and a sensor that is provided with a sensor chamber at the other end of a conductive rod that has one end pressed against the hollow bottom inside the vibration tube and that is detachably mounted near the vibration tube support. Transmitting the transverse vibration acting on the vibrating tube by the fluctuating differential pressure of the Karman vortex introduced from the pair of differential pressure introducing holes via the transmission rod to detect the longitudinal vibration in the sensor chamber, and (2) )
In the (1), the pressing force for pressing one end of the vibration tube wherein the sensor and the <br/> conducting rod is arranged adjustably, further, (3) (1) or (2 )smell
Te, wherein a taper narrowing towards the shape bottom of the vibrating tube hollow bottom, that the end shape of the conductive rod to the tapered pressure contact with a thin tubular, further, (4) the
(1) In (1) or (2), the shape of the hollow bottom inside the vibrating tube is a taper narrowed toward the bottom, and a press-contact portion of the conductive rod that presses against the taper is provided with a groove on an end diameter of the conductive rod. , the contact piece which is formed by the groove, it has disposed該接piece horizontal vibration direction, and further, (5) the
(1) or (2), the vibration tube a hollow bottom of the feature bottom and that provided a small diameter hollow in the vicinity, slightly larger than the diameter of the hollow at one end of the conductive rod which presses the said small diameter hollow wall A thin thin disk is fixed, and the thin disk is elastically pressed against the small-diameter hollow wall.
(6) In the above (1) or (2), one end of the conductive rod wherein the shape of the vibrating tube hollow bottom and that provided a small diameter hollow near the bottom, into pressure contact with said small diameter hollow wall
The is obtained and characterized in that a disc-shaped outer diameter of the extent in contact with the small-diameter hollow. Hereinafter, a description will be given based on examples of the present invention.

FIG. 1 is a block diagram for explaining an embodiment of a sensor for a Karman vortex flow meter according to the present invention.
Is a flow tube, 2 is a vortex generator, 3 is a flow path, 4 and 4 are differential pressure introduction holes, 5 is a long hole, 6 is a mounting surface, 7 is a vibration tube, 8 is a hollow portion,
9 is a hollow bottom, 10 is a mounting flange, 11 is a screw hole, 1
2 is a sensor, 13 is a conduction rod, 14 is a press-contact end, 15 is a sensor chamber, 16 is a detection element, 17 is a filler, 18 is a lead wire, 19 is a flange, 20 is a cap nut, 20a is a fixing screw,
20b is a lock nut, 21 is a conduit, 22 is a terminal box, 23 is a hermetic seal, and 24 is an output terminal.

In the figure, both ends of a vortex generator 2 are fixed in a flow tube 1, and the vortex generator 2 divides a flow path 3 symmetrically. A long hole 5 penetrating through one wall surface of the flow tube 1 in the axial direction of the vortex generator 2 is formed in the vortex flow meter body integrally formed as described above.
The differential pressure introducing holes 4, 4 opened on both side surfaces of the vortex generator 2 communicate with the long hole 5. An end face of the flow tube wall of the elongated hole 5 becomes a mounting surface 6, and a mounting flange of the vibrating tube 7 is fixed to the mounting surface 6 by a bolt hole 11. The vibrating tube 7 is provided with a hollow portion 8 having a hollow bottom portion 9, and a pressure receiving plate 7 a is further formed at an end portion, and is processed at normal temperature. The pressure receiving plate 7a is not always necessary, and in this case, the vibration tube 7
Extends to the end of the illustrated pressure receiving plate 7a.

One end of the conductive rod 13 of the sensor 12 is in contact with the hollow bottom 9. The sensor 12 is the conductive rod 1
3 and a sensor chamber 15, and detection elements 16, 16 are fixed to the bottom of the sensor chamber 15 symmetrically with the axis of the conduction rod 13. The detecting elements 16 and 16 may be any elements such as a piezoelectric element plate, a strain gauge, a capacitance, a light converting means, etc., as long as the strain is converted into another physical quantity. When the detecting elements 16 and 16 are piezoelectric elements, glass is used as a filler 17 to be tightly adhered and solidified in the sensor chamber 15, and the lead wire 18 is connected to the conduit 21 and the terminal box 2.
The two hermetic seals 23 block the outside air and prevent the insulation resistance from lowering.

The sensor 12 can be adjusted so that it can be moved in the axial direction of the conductive rod 13 by the vibrating tube 7 and the tightening cap nut 20, and the pressure contact end 14 of one end of the conductive rod 13 is pressed against the hollow bottom 9 of the vibrating tube 7. The flange 19 secures the fixing screw 20a and the lock nut 20b.
Since the conductive rod 13 and the hollow bottom 9 are pressed against each other, it is necessary that the pressure contact end can elastically transmit vibration. In the illustrated example, the hollow bottom 9 is tapered toward the lower end, and the pressure contact end 14 is a thin tubular member. Hole 25 in the center of the end
Is provided.

As described above, the flow tube 1, the vibrating tube 7 and the sensor 12 are integrally assembled so as to be detachable, and the fluctuation pressure of the vortex generated when the fluid to be measured flows through the flow path 3 is a differential pressure introducing hole. 4, the pressure receiving plate 7a is caused to vibrate in the horizontal direction as shown in FIG. The lateral vibration is caused by the transmission rod 1
The sensor chamber 15 is vibrated by 3 and is converted into a longitudinal vibration in the sensor chamber 15 and converted into an electric signal as a distortion amount alternately distorting the detecting elements 16 and 16 in opposite directions.

As described above, the vortex signal is transmitted to the vibrating tube 7.
Since the vibration direction is changed and detected by the sensor 12 which is detachably fixed to the sensor, a small detecting section can be obtained, so that the amount of the filler 17 can be reduced and the fixing can be stabilized. Further, since the vibration tube 7 can be processed at room temperature, the material of the material is processed in a stable state without causing a structural change, so that the vibration resistance is increased and the fatigue strength is increased. Further, since the vibration tube 7 itself becomes a pressure-resistant container, it can be replaced even while the sensor 12 is being measured. There are various methods for press-contacting the hollow bottom portion 9 serving as the vibration transmitting portion and the press-contact end 14.

FIGS. 2 (a), 2 (b), 2 (c) and 2 (d) show another embodiment of the pressure contact structure of the Karman vortex flowmeter sensor according to the present invention. The same reference numerals are given to portions having the same operation as. The press-contact portion structure shown in FIG.
This is indicated by a and has the structure described above, and the description is omitted. In the press-contact structure shown in FIG. 2B, the press-contact end 26 is provided with a groove 26 perpendicular to the axis on the diameter of the end of the conductive rod 13, and both side portions 26a of the groove are used as pressing contacts. Reference numeral 26a is a member that contacts the tapered hollow bottom portion 9a by lateral vibration and transmits vibration.

In the pressure contact structure shown in FIG. 3C, a hollow 9b having a smaller diameter is provided at the hollow bottom 9 of the vibrating tube 7, and the hollow 9b having a smaller diameter is provided.
A thin disk 27 having a diameter slightly larger than the diameter of the hollow 9b is fixed to the end of the conductive rod 13 which is pressed against the wall surface of the hollow 9b, and the thin disk 27 is elastically pressed against the wall surface of the hollow 9b. In the press-contact portion structure shown in FIG. 6D, a small-diameter hollow 9b is provided in the hollow bottom 9 of the vibrating tube 7 as in FIG.
A disk 28 having an outer diameter enough to bring the end of the transmission rod 13 into contact with the hollow 9b is integrally formed on the wall surface of.

[0022]

As is apparent from the above description, according to the present invention, the sensor can be easily manufactured, the corrosion resistance and the insulation can be improved, and the sensor can be replaced during operation. More specifically, the following effects can be obtained. (1) Since the vibrating tube is not heat-treated at high temperature without glass filling or the like, corrosion resistance and strength do not deteriorate. (2) Since the direction of vibration is changed and the detection elements are juxtaposed, the sensor chamber becomes a small-capacity sensor. Even if glass is sealed, it is only a part of the sensor chamber and is easy to manufacture. (3) Even if glass sealing is performed, since the sensor is not deep, it is easy to dry the sensor. (4) Since the sensor can be installed at a place away from the fluid,
Even if a high-temperature fluid flows, the temperature rise of the sensor is small. (5) Since the sensor is a cassette type, the sensor can be replaced during operation.

[Brief description of the drawings]

FIG. 1 is a configuration diagram for explaining an embodiment of a sensor for a Karman vortex flowmeter according to the present invention.

FIGS. 2 (a), (b), (c), and (d) are diagrams showing another embodiment of the pressure contact structure of the Karman vortex flowmeter sensor of the present invention.

3 (a) and 3 (b) are structural views of the conventional vortex flowmeter, and FIG. 3 (a) is a cross-sectional view as viewed from the flow direction, and FIG. 3 (b).
FIG. 2 is a view taken along line AA of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flow tube 2 Vortex generator 4 Differential pressure introduction hole 5 Slot 7 Vibration tube 12 Sensor

Claims (6)

(57) [Claims] 1. A formed integrally flow tube and the vortex generation body, a body having a long hole communicating with the pair of differential pressure introducing hole opened on both sides of the vortex generator, the flow is inserted into the long hole A hollow vibration tube having a bottom that is cantilevered on the tube wall, and a sensor chamber is disposed at the other end of the conductive rod having one end pressed against the hollow bottom inside the vibration tube, and is detachably disposed near the vibration tube support. The lateral vibration acting on the vibrating tube by the fluctuation differential pressure of the Karman vortex introduced from the pair of differential pressure introduction holes via the transmission rod and detecting the longitudinal vibration in the sensor chamber. Characteristic sensor for Karman vortex flowmeter. 2. A cell for a Karman vortex flowmeter according to claim 1.
In capacitors, characteristics and to Luke mans vortex flowmeter sensor that pressing force for pressing the one end of the conductive rod and the said vibrating tube sensors are arranged adjustably. 3. The Karman vortex flow rate according to claim 1 or 2.
In the measuring sensor, the shape of the hollow bottom inside the vibrating tube is a taper narrowed toward the bottom, and before being pressed against the taper.
Serial Luke Le Mans flowmeter sensor to <br/> characterized in that one end shape of the conductive rod has a thin-walled tubular. 4. The Karman vortex flow rate according to claim 1 or 2.
In the measuring sensor, the shape of the hollow bottom inside the vibrating tube is a taper narrowed toward the bottom, and before being pressed against the taper.
Serial grooves provided pressure contact portion of the conductive rod on the end diameter of the conductive rod, the contact piece which is formed by the groove, wherein the to Luke Le Mans vortices that were provided with該接piece transverse vibration direction Sensor for flow meter. 5. A Karman vortex flow rate according to claim 1 or 2.
In sensor meter, the vibration tube hollow bottom shape assumed in which a small-diameter hollow near the bottom of, the small-diameter hollow wall and pressed to the conductive slightly large diameter thin disk than said small diameter hollow at one end of the rod A sensor for a Karman vortex flowmeter, wherein a plate is fixedly attached , and the thin disk is elastically pressed against the small-diameter hollow wall. 6. The Karman vortex flow rate according to claim 1 or 2.
In sensor meter, the vibration tube is assumed in which a small-diameter hollow the hollow bottom of the feature near the bottom circle of the outer diameter of the extent to which one end of the conductive rod which presses the said small diameter hollow wall in contact with the small-diameter hollow It features and to Luke <br/> mans vortex flowmeter sensor that it has a plate-like.