JPH0815293A - Flow velocity measurement device for liquid - Google Patents

Abstract

PURPOSE:To eliminate the need of immersing a sensor section in liquid and preparing a calibration curve therein, and easily find a flow velocity value, regardless of the type of the liquid as a measurement object. CONSTITUTION:This device consists of a rod 1 fixed to a pillar 8 in a downward direction, and a sensor 3 fixed to the upper section of the rod 1. The sensor 3 has strain signal generators 5 and two of the generators 5 are arranged in two tiers at 90-degree turned positions. The cavity sections of the generators 5 are provided respectively with a bulge section formed out of four curvatures up and down, and right and left. In addition, the device features that a strain gauge 6 is attached to the side thereof adjacent to respective bulge sections.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid flow velocity measuring device.

[0002]

2. Description of the Related Art As a device for measuring the flow velocity of liquid, for example, a device for measuring the flow velocity of molten metal, an electromagnetic velocity meter, an ultrasonic velocity meter and the like can be mentioned. The electromagnetic velocity meter is disclosed in JP-A-55-12815.
There is one disclosed in Japanese Patent No. 6 and a sectional view of the tip of the sensor is shown in FIG. This anemometer is induced by the magnetic field generated by the coil and the flow of molten metal,
The flow velocity value of the molten metal around the detector is detected.

An ultrasonic velocity meter is disclosed in Japanese Patent Laid-Open No. 56-706.
There is one disclosed in Japanese Patent Publication No. 8 and this velocimeter radiates ultrasonic waves into the molten metal and obtains the flow velocity value of the molten metal from the change in the sonic velocity due to the flow of the molten metal.

[0004]

The structure of the electromagnetic anemometer shown in FIG. 6 has the first sensor part for detecting the velocity value.
Since the electrode 12 and the second electrode 14 are in direct contact with the molten metal 19, there is a limit to the heat resistant temperature of the electrode, and it cannot be used for measuring the flow velocity of a molten metal at high temperature such as molten steel.

The ultrasonic velocity meter is effective for measuring a linear velocity such as a flow in a pipe because it radiates an ultrasonic wave into molten metal, but there is a distribution in the flow or a drift or a swirling flow. When it becomes, it cannot be used.

Therefore, the inventors of the present invention are composed of a rod fixed downward to a support and a sensor having a strain gauge attached above the rod. The sensor has two strain-generating bodies, which are arranged in two stages at 90 ° -turned positions. It has been proposed to provide a liquid flow velocity measuring device characterized in that a plurality of strain gauges are attached to one strain-generating body (Japanese Patent Application No. 4-348926).

However, in the liquid velocity measuring device of Japanese Patent Application No. 4-348926 mentioned above, the force received by the rod may be very weak depending on the type of liquid, and it may be difficult to evaluate the measured value. It was

Therefore, the inventors of the present invention have completed the present invention by studying the optimum flexure body structure in order to improve the sensor detection sensitivity in a liquid flow velocity measuring device.

[0009]

[Means for Solving the Problems] That is, the present invention comprises a rod fixed downwardly to a column and a sensor having a strain gauge attached above the rod.
Degrees should be provided in two stages at different positions, and the cavity of the strain-flexing body should be provided with overhangs formed by four curved surfaces in the vertical and horizontal directions, and strain gauges should be attached to the side faces adjacent to each overhang. Is a liquid flow velocity measuring device.

The present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a schematic view for explaining a liquid flow velocity measuring device of the present invention.

As shown in FIG. 1, the present invention comprises a rod 1 fixed downwardly to a column 8 and a sensor 3 fixed above it. The rod 1 may be made of any material as long as it is a rigid body, but when the liquid 10 to be measured is a high temperature molten metal, it is preferably a refractory material. The material of the sensor 3 is mainly aluminum having a small Young's modulus.

A front view of the sensor 3 is shown in FIG. 2, and a front view obtained by rotating the sensor 3 of FIG. 2 by 90 ° is shown in FIG. As shown in FIGS. 2 and 3, the sensor 3 is provided with 9 strain elements 4 and 5.
It is installed in two steps at a position where the direction is changed by 0 °. Explaining the flexure element 4 as an example, the flexure element 4 has overhang portions 4-A, 4-B, 4-C, and 4-D formed by four curved surfaces in the vertical and horizontal directions.
To provide. Overhang part 4-A, 4-B, 4-C, 4-D
As a result, the drag force received by the rod 1 is concentrated at the positions A, B, C and D on the side surfaces adjacent to the projecting portion. Strain gauges 6-A, 6-B, 6-C and 6-D are attached to the positions A, B, C and D as shown in FIGS. These strain gauges connect 6-A and 6-B, 6-C and 6-D to a Wheatstone bridge circuit, respectively, and connect them to a dynamic strain gauge.

Although the flexure element 4 has been described,
The flexure element 5 is different from the flexure element 4 only in that the direction is changed by 90 °, and the structure of the projecting portion is the same as that of the flexure element 4.

When measuring the flow velocity of the refractory metal, it is desirable to use a heat resistant cover 9 as shown in FIG. 1 in order to prevent the temperature rise of the strain gauge 6 and the thermal deformation of the sensor 3.

[0016]

In the liquid flow velocity measuring apparatus of the present invention, the rod 1 is immersed in the liquid 10 and the drag force received by the flow 11 of the liquid 10 is detected by the strain gauge 6 as the strain amount. As an example, a method of measuring the flow velocity of the liquid flowing from the left side as shown in FIG. 1 will be described. The rod 1 is subjected to a drag force by the flow 11 of the liquid 10, and the drag force exerted by the flow 11 by the four strain gauges 6-A, 6-B, 6-C and 6-D of FIGS. The amount of distortion corresponding to is detected. Strain gauges 6-A and 6-B and 6-C and 6-
By connecting D in parallel, it is possible to obtain a large amount of distortion at the positions AB and CD.

If the measured strain amount of the strain gauge 6-A is ε _A , ε _A can be theoretically expressed by the following equation.

[0018]

[Equation 1]

Further, the strain amount measured by the strain gauge 6-C is expressed by ε
_{If C} , ε _C can be expressed by the following equation.

[0020]

[Equation 2]

Describing the symbols, F: drag force exerted on the rod 1 by the flow 11 M: bending moment between the rod 1 and the strain gauge 6 V: tensile force generated when the rod 1 receives the drag force T: Torsional torque of the rod 1 that works when the flow is not uniform E: Young's modulus of the material used for the sensor 3 Z: Section coefficient of the sensor 3 at the strain gauge attachment positions A, B, C, D S: Liquid projected cross-sectional area of the bar 1 was immersed part in 10 alpha: thermal diffusivity of the bar 1 and the sensor 3 beta: volume expansion coefficient of the rod 1 and the sensor 3 T _o: temperature x: position CD from a position for receiving a force F Distance t: Distance between position AB and position CD By taking the difference between the above equations (1) and (2),

[0022]

(Equation 3)

Therefore, regardless of the moment M, it is possible to detect only the amount of strain proportional to the drag force F that the rod 1 receives by the flow 11. Since the strain amount ε _B of the strain gauge 6-B is almost the same as ε _A and the strain amount ε _D of 6-D is the same as ε _C , the relation between ε _B and ε _D is also (3). The formula holds.

From the equation (3), it is the distance t between the position AB and the position CD and the section coefficient Z that change depending on the structure of the strain generating elements 4 and 5. By providing the flexures 4 and 5 with overhanging portions,
The stress concentrates at B, C, and D, and the strain amount more than that calculated by the equation (3) can be expected.

When the strain amount is converted into the flow velocity value of the flow 11, first, the correlation between the load value received by the rod 1 and the strain amount is investigated off-line. The liquid flow velocity measuring device of the present invention,
As described above, since there is no influence of the drag force exerted on the rod 1 and the moment between the strain gauges 6, it is not necessary to perform the test in a liquid.

After the resistance applied to the rod 1 is obtained from the amount of strain based on the result of the off-line verification, the flow velocity value U of the flow 11 is calculated from the hydrodynamic theory. When converting the drag force into the flow velocity value U, the following equation is used.

[0027]

[Equation 4]

Describing the symbols here, F: drag force exerted on the rod 1 by the flow 11 ρ: density of the liquid 10 S: projected cross-sectional area of the rod 1 immersed in the liquid 10 Cd: cross section of the rod 1 The shape and resistance coefficient determined by the Reynolds number of the flow 11 The above description is for the flow 11 from the left side of FIG. 1, but the sensor has a shape in which the two-stage flexure elements 4 and 5 are turned by 90 °. Since it has the same value as above, the direction of the flow of the liquid 10 can also be measured together.

[0029]

The detection sensitivity of the flow velocity measuring device according to the present invention greatly depends on the shapes of the overhanging portions 4-A, 4-B, 4-C and 4-D. Therefore, a test was performed in which the shape of the flexure element 4 was changed, and a strain gauge 6-when a load was applied to the rod 1.
The strain amount obtained from A, 6-B, 6-C, 6-D was measured.

The structure of the sensor 3 used in the test is shown in FIG.
(A) and (b). The sensor was manufactured with the same distance d between the projecting portion and the adjacent side surface and the distance t between the position AB and the position CD, and the effect of the projecting portion according to the present invention was investigated.

The test results are shown in FIG. from this result,
It was found that the shape of FIG. 4 (b) obtained a strain amount about twice that of the present invention, and that the present invention improves the detection sensitivity of the sensor.

[0032]

The liquid flow velocity measuring device of the present invention is not affected by the moment even if the rod acting on the liquid and the sensor for detecting the strain are apart from each other, so that only the drag force applied to the rod is accurately measured. Since the sensor does not have to be directly immersed in the liquid, the liquid to be measured is water,
It can be applied to various materials such as high melting point molten metal.

When performing the off-line verification, it is not necessary to perform calibration with the kind of liquid for measuring the flow velocity and the known flow velocity value as in the conventional case. Only the density of the liquid is needed to calculate the flow velocity value, and a calibration curve can be created very easily. In addition, the sensor has two strain-flexing parts with their directions changed by 90 °, so that the direction of the flow of the liquid can also be measured together.
The detection sensitivity of the sensor is further improved as compared with the liquid flow velocity measuring device proposed in 8926.

[Brief description of drawings]

FIG. 1 is a front view of an embodiment of the present invention, and an outer case shows a cross section.

FIG. 2 is an enlarged front view showing a sensor 3 shown in FIG.

FIG. 3 is an enlarged side view showing a rod of the sensor 3 shown in FIG.

4 (a) and 4 (b) are front views of a sensor used when a test in which a flexure structure is changed is performed,
(A) shows a comparative example, (b) shows an example of the present invention.

5 is a graph showing the results of an investigation of the relationship between the load applied to the rod by the sensor shown in FIGS. 4 (a) and 4 (b) and the strain amount obtained by the strain gauge, and the broken line in FIG. 4), the solid line shows the example of the present invention shown in FIG. 4B.

FIG. 6 is a sectional view showing a structure of an electromagnetic flowmeter disclosed in Japanese Patent Laid-Open No. 55-128156.

[Explanation of symbols]

1: Bar 2: Jig 3: Sensor 4,5: Strain element 6: Strain gauge 7: Jig 8: Strut 9: Heat-resistant cover 10: Liquid 11: Liquid flow 12: First electrode 13: Insulating cylinder 14: 2nd electrode 15: Core 16: Coil 17: Filler 18: Conductive wire 19: Molten metal

Front page continuation (72) Inventor Machida Kazuki Kimitsu 1 Kimitsu, Nippon Steel Co., Ltd. Kimitsu Steel Works (72) Inventor Mitsuo Matsumoto 1 Kimitsu City Kimitsu Shin Nippon Steel Co., Ltd. Tsu Steel Works

Claims (1)

[Claims] 1. A bar comprising a rod fixed downward to a column and a sensor having a strain gauge attached above the rod. The sensor is provided with two flexures, which are provided in two stages at 90 ° -turned positions. The liquid flow velocity measuring device is characterized in that the cavity portion of the flexure element is provided with protruding portions formed of four curved surfaces in the vertical and horizontal directions, and a strain gauge is attached to a side surface adjacent to each protruding portion.