JP4411917B2 - Vortex flow meter - Google Patents

Description

  The present invention relates to a small vortex flowmeter in which a measurement pipe line and a vortex generator are made of a metal body, and a vortex detector is made of a synthetic resin material.

  Prior art documents related to vortex flowmeters include the following.

FIG. 2 is an overall configuration diagram of a conventional synthetic resin type vortex flowmeter. (A) is an upper sectional view, (B) is a sectional side view, and (C) is viewed from the downstream side. (Arrow P) It is a front view. 1 is a body case molded from a synthetic resin material, and 1a is a measurement pipe line into which the fluid F to be measured is introduced from the upstream side.

Reference numeral 2 denotes a columnar vortex generator having a substantially trapezoidal cross section, and is arranged so as to be orthogonal to the measurement pipeline at the center of the measurement pipeline 1a.
The vortex generator 2 is molded of a synthetic resin material integrally with the body casing 1, and the width on the upstream side orthogonal to the measurement pipeline 1a is 0.28 times the diameter of the measurement pipeline according to the standard. Yes.

  As the synthetic resin material, PPS resin (polyphenylene sulfide resin) is used when the fluid F to be measured is general industrial water, and PFA resin (tetrafluoroethylene / perfluoroalkoxyethylene copolymer resin) when it is pure water or chemical liquid. ) Etc. are used.

  Reference numeral 3 denotes a vortex detector formed of a synthetic resin material. The block of the vortex detector 3 is inserted and fixed orthogonally into the measurement pipe line 1a through a hole 1b formed through the upper tube wall of the body housing 1 on the downstream side of the vortex generator 2.

The detection part inserted and exposed in the measurement pipe 1a at the tip of the vortex detector 3 is formed in a vane shape having a thickness of 1 mm to 2 mm in order to be easily bent due to fluid pressure fluctuation caused by the vortex. .
Reference numeral 4 denotes a piezoelectric bimorph sensor, which is embedded and fixed in the vane-shaped detection unit 3a, and detects the pressure fluctuation of the fluid due to the vortex with high sensitivity.

As is apparent from FIG. 2C, the measurement pipe 1a has a horizontally long oval shape in order to increase the flow velocity in the vicinity of the vortex generator 2 and the vortex detector 3.
D1 is the pipe diameter in the vertical direction, D2 is the pipe diameter in the horizontal direction, h is the height of the vane detection unit 3a exposed in the measurement pipe 1a, and t is the thickness of the vane detection unit 3a.

  As a product currently in practical use, the small product (case 1) has a shape of D1 = 2.5 mm, D2 = 5 mm, h = 1.75 mm, t = 1 mm and a measurement flow rate span of 0.5 L to There are 4L / min.

  Larger ones (case 2) have a shape of D1 = 12 mm, D2 = 24 mm, h = 0.75D1 = 9 mm, t = 2 mm, and a measurement flow rate span of 10 L to 150 L / min.

  In order to flow a larger flow rate than this, the measurement pipe must naturally be enlarged. For example, when the measurement flow rate span is designed to be 25 L to 350 L / min (case 3), the shape becomes D1 = 30 mm, D2 = 30 mm, h = 0.75D1 = 22.5 mm, t = 2.0 mm. .

  The problem here is the height h of the vane-shaped detector 3a. This height h is required to have a constant ratio with respect to the diameter of the pipe line in order to ensure the sensitivity of vortex detection, and is 22.5 mm in the case 3 and needs to be longer than 9 mm in the case 2.

  However, when the length is increased, the vortex generation period and the resonance frequency of the resin material forming the vortex detector 3 become close, and the vortex detector is damaged, so that it is difficult to maintain reliability with respect to vibration resistance. .

Next, when the fluid F to be measured is high at a high temperature (for example, 150 ° C.), in the case of the body housing 1 made of synthetic resin, the strength of the resin decreases due to the temperature dependence of the material strength. Insufficient pressure resistance against internal pressure.
In addition, the deformation of the body case 1 made of synthetic resin prevents an accurate vortex from being generated. Also, in order to increase the strength, the body case 1 and the vane detector 3a of the vortex detector 3 are made of metal. In this case, the strength of the vane detection unit 3a is too strong and the detection sensitivity is lowered.

  The object of the present invention is to solve the above-mentioned problem, and even if the diameter of the measurement pipe is enlarged, the height of the vane-shaped detection part of the vortex detector exposed in the measurement pipe is maintained at the same level as the conventional one. A vortex flowmeter capable of ensuring vortex detection sensitivity is realized.

  Moreover, the body housing 1 without deformation can be obtained even for a high temperature fluid to be measured, and a clean vortex waveform can be detected, and the elasticity is ensured by using a vortex detector made of synthetic resin. An object of the present invention is to provide a vortex flowmeter that can improve detection sensitivity.

In order to achieve such a problem, in the present invention, in the vortex flowmeter of claim 1,
In the vortex flow meter for measuring the flow rate by Karman vortices, and measurement line in which the measurement fluid consisting flowing metal, the Ri upstream end portions name of a metal which generates a vortex in said measuring fluid edges machined columnar vortex generator In order to improve the detection sensitivity so that the vortex flowmeters having different inner diameters can be easily accommodated with a single vortex detector, a predetermined height with respect to the height D of the vortex generator is provided at the upper part on the downstream side of the vortex generator. the height to form a L-shaped notch having the characterized by comprising a vortex detector ing a synthetic resin having a height h over a predetermined gap to the notch.

In claim 2 of the present invention, in the vortex flowmeter according to claim 1,
The height h is approximately in the range of h = 0.2D to 0.4D with respect to the height D.

In Claim 3 of the present invention, in the vortex flowmeter according to any one of Claims 1 to 2,
The width on the downstream side of the vortex generator and the thickness of the vortex detector are substantially the same.

According to a fourth aspect of the present invention, in the vortex flowmeter according to any one of the first to third aspects,
A piezoelectric bimorph type sensor is embedded in the vortex detector.

In claim 5 of the present invention, in the vortex flowmeter according to any one of claims 1 to 4 ,
The inner diameter of the measurement pipe is approximately 25 mm.

The present invention has the following effects.
A body case without deformation is obtained even for high-temperature fluids to be measured, and a clean vortex waveform can be detected. By using a vortex detector made of synthetic resin, elasticity is ensured and detection sensitivity is improved. A vortex flowmeter can be obtained.

The vane-shaped detector can detect the part immediately after the vortex separation, that is, the part with the largest pressure fluctuation immediately downstream of the vortex generation point, so it can detect a clean vortex waveform and increase the detection sensitivity of the vortex signal. it can.
As a result, the length of the vane-shaped detection part of the vortex detector can be shortened, so that a vortex flowmeter for high flow rate measurement with high sensitivity and excellent vibration resistance can be realized.
For this reason, an already proven vortex detector can be used as it is, and the cost can be reduced.
That is, a vortex flowmeter that can easily cope with vortex flowmeters having different inner diameters with a single vortex detector can be obtained.

Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is an explanatory view of the main part configuration of an embodiment of the present invention, (A) is an upper cross-sectional view cut along a plane including a vane-shaped detector 3a, and (B) is a plane including the vane-shaped detector 3a. FIG. In the figure, the same symbol structure as in FIG. 2 represents the same function.
Only the differences from FIG. 2 will be described below.

In the figure, the structure of the vortex generator 12 is basically the same as that of the prior art, and is integrally formed with the body housing 11 but made of a metal material.
In the present invention, the measurement pipe 11a and the vortex generator 12 are made of a metal body, and the height D of the vortex generator 12 (same as the diameter of the measurement pipe 11a) is formed on the upper portion on the downstream side of the vortex generator 12. An L-shaped notch 12a having a predetermined height is formed on the vortex detector made of a synthetic resin having a height h through a predetermined gap (approximately 0.5 mm) X in the notch 12a. The vane detector 3a is disposed.

As described above, the width L1 on the upstream side of the vortex generator 12 is 0.28D in the standard as described above (D in this case is the diameter when the measurement pipe 11a is a circle).
The width L2 on the downstream side where the cutout portion 12a is formed is designed to be substantially the same as the width t of the vane-shaped detection portion 3a.

A hole 11b formed through the body housing 11 is formed in the upper portion of the notch 12a, and the block of the vortex detector 3 is inserted through the hole 11b, and the body housing is inserted through an O-ring material. It is fixed to the body 11 with screws.
In this fixed state, the vane-shaped detection unit 3a is disposed in the notch 12a with a predetermined gap X interposed therebetween.

As a result,
A body case without deformation is obtained even for high-temperature fluids to be measured, and a clean vortex waveform can be detected. By using a vortex detector made of synthetic resin, elasticity is ensured and detection sensitivity is improved. A vortex flowmeter can be obtained.

Since the pressure fluctuation immediately downstream of the vortex generation point can be detected at the largest portion, the height h of the vane-shaped detection portion 3a is not required to be 0.75D as in the conventional structure, and the height D of the vortex generator 2 is not required. On the other hand, vortices can be detected with high sensitivity in a ratio range of approximately h = 0.2D to 0.4D.
Therefore, even in the case 3, the height h of the vane-shaped detector 3a can be made the same as that in the case 2, and both the vibration resistance and the quality of detection sensitivity can be achieved.
That is, a vortex flowmeter that can easily cope with vortex flowmeters having different inner diameters with a single vortex detector can be obtained.

The effect of the measurement pipe line 11a to which the present invention can be applied is not limited to an oval, but can be circular or square.
Further, it is possible to add an R to the upstream edge portion of the vortex generator 2, chamfering, or taper processing.

  In the drawing of the embodiment, the downstream end of the vane-shaped detector 3a and the downstream end of the vortex generator 12 are on the same plane, but the downstream end of the vane-shaped detector 3a is L-shaped. The effect is the same even if shifting to the inside or outside of the notch.

It is principal part structure explanatory drawing of one Example of this invention. It is a whole block diagram of the conventional synthetic resin type vortex flowmeter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 Vortex detector 3a Vane-shaped detection part 11 Body housing 11a Measurement pipe line 11b Hole part 12 Vortex generator 12a L-shaped notch F Measurement fluid

Claims (5)

In the vortex flowmeter that measures the flow rate by Karman vortex,
A measurement pipe made of a flowing metal and a measurement fluid;
A columnar vortex generator to the upstream end portions are edging Ri name of a metal which generates a vortex in said measurement fluid,
In order to improve detection sensitivity so that a single vortex detector can easily cope with vortex flowmeters having different inner diameters, a predetermined height is set on the downstream side of the vortex generator with respect to the height D of the vortex generator. vortex flowmeter characterized by comprising a vortex detector ing a synthetic resin having a height h over a predetermined gap to the notch to form a L-shaped notch with. The vortex flowmeter according to claim 1, wherein the height h is in a range of approximately h = 0.2D to 0.4D with respect to the height D. The vortex flowmeter according to claim 1 or 2, wherein the downstream width of the vortex generator and the thickness of the vortex detector are substantially the same. The vortex flowmeter according to any one of claims 1 to 3, wherein a piezoelectric bimorph type sensor is embedded in the vortex detector. The inner diameter of the measurement pipe is approximately 25 mm.
  A vortex flowmeter according to any one of claims 1 to 5.

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