JPH11211741A - Method and apparatus for measuring flow velocity - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for measuring a flow velocity whereby a flow velocity of a conductive moving object to be measured (e.g. high-temperature liquid metal) can be stably and accurately measured even when a measurement face is wavy. SOLUTION: According to a method and an apparatus for measuring a flow velocity, a magnetic field perpendicular to a surface of a moving conductive object to be measured is excited (excitation winding P), and magnetic fields at the surface of the object and in a direction parallel to a movement direction are detected in two ranges (detection windings S1 , S2 ), whereby a flow velocity of the object is calculated from the detected magnetic field signals. In the method and the apparatus, magnetic fields in the direction parallel to the movement direction of the object are detected in two ranges outside the detection ranges of the detection windings S1 , S2 (detection windings S3 , S4 ), and the calculated flow velocity of the object is corrected on the basis of information related to an inclination of the surface of the object which is obtained on the basis of the detected magnetic field signals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring a flow velocity of a surface of a molten steel flow in a mold for casting molten steel in a continuous casting process.

[0002]

2. Description of the Related Art In a continuous casting line, as shown in FIG.
2 and poured into a copper mold 104 and cast. The molten steel poured into the mold hits the mold wall and is divided into an upflow 107 and a downflow 108. The ascending flow creates flows 109a and 109b on the surface. If the left and right balance of the molten steel flow on the surface is lost, a vortex is generated and the powder 105 scattered on the molten steel surface is involved (111). When the molten steel flow on the surface becomes excessive, powder on the molten steel surface is shaved (110). In any case, inclusions are trapped in the slab, which causes product defects. For this reason, stabilizing the flow of molten steel in a mold is a very important task, and it is strongly required to continuously measure the flow velocity near the surface of molten steel.

Conventionally, the flow rate of molten steel is, for example, disclosed in
Contact type measurement as shown in Japanese Patent No. 774 is mainly used. In this method, as shown in FIG. 25, a rod 112 made of fine ceramics is immersed in molten steel 114, and the pressure received by the rod due to the molten steel flow is detected by a pressure receiving sensor 113 to measure the flow velocity. In this method, a ceramic rod is immersed in high-temperature molten steel, so that long-term continuous measurement is impossible.

On the other hand, it is known that the speed can be measured in a non-contact manner using magnetism. When the conductor 115 moves in the uniform magnetic field Bo as shown in FIG. 26A, a speed electromotive force Ev = v × Bo is generated in the conductor. The velocity electromotive force Ev induces an induced current Jv in the conductor, generates an induced magnetic field Bv on the conductor, and distorts the original magnetic field from Bo to B so as to be dragged in the velocity direction of the conductor. Such an effect that the magnetic field is distorted by the movement of the conductor is hereinafter referred to as a velocity effect of the magnetic field. Since the degree of distortion due to the speed effect changes in accordance with the speed of the conductor, the speed of the target conductor can be known by measuring the amount of distortion. It is clear that measuring this distortion is nothing but measuring Bv because the source of the distortion is the induced magnetic field Bv due to the velocity effect. Bv can be expressed by the following equation (1).

[0005]

(Equation 1)

[0006] In the method of measuring the flow velocity using a magnetic field, in addition to the signal magnetic field Bv due to the velocity electromotive force to be measured as shown in FIG. An eddy current Je is generated due to -dB / dt flowing through the eddy current, and an eddy current magnetic field Be due to the eddy current is detected. Now, the flow velocity of the molten steel flow in the mold to be measured is 0 to 0.
Since it is as small as about 3 m / sec, the signal magnetic field Bv due to the speed electromotive force is also small, and when the excitation frequency is as high as several tens Hz or more, it becomes significantly smaller than the eddy current magnetic field Be.
When Be fluctuates, Bv is buried in the fluctuation, and there is a problem that a large measurement error occurs. The eddy current magnetic field Be causes an offset of the flow velocity signal to vary irrespective of the flow velocity of the target.

An apparatus for measuring the speed in a non-contact manner using such magnetism is disclosed in Japanese Patent Application Laid-Open No. 2-31766. As shown in FIG. 27A, a primary coil 119 is arranged in parallel with a flow 118 of molten steel, and two secondary coils 120a and 120b are arranged on both sides in the horizontal direction. An alternating current is applied to the primary coil to apply an alternating magnetic field 117 parallel to the molten steel surface, and the secondary coil detects a magnetic field parallel to the target surface. When the conductor is stationary, the magnetic field becomes symmetrical with respect to the primary coil, and there is no difference between the electromotive forces of the two secondary coils and the output is zero. When the conductor is moving, the magnetic field is distorted in the velocity direction of the conductor due to the velocity effect and is not symmetrical across the exciting coil as shown in FIG. 27B, so that the electromotive force generated in the two secondary coils is reduced. A difference is generated, and a signal corresponding to the distortion amount of the magnetic field, that is, the speed is obtained as a difference signal between the two secondary coils.

In the method using magnetism, the speed sensitivity changes depending on the distance between the device and the object to be measured (hereinafter, referred to as lift-off). Is measured by the output voltage of one of the secondary coils for detecting a magnetic field parallel to the target surface, and correction is performed.

Another method for measuring speed using magnetism is disclosed in Japanese Patent Application Laid-Open No. 5-297012. As shown in FIG. 28, the primary coil 151 is arranged perpendicular to the measurement object 152, an alternating current is applied to the primary coil 151, a magnetic field 153 is generated, and the primary coil 151
The secondary coils 154a and 154b are disposed on both sides of the primary coil
Iron core 15 wound with primary and secondary coils 154a and 154b
5, 156a and 156b. The flow rate was detected from the phase of the electromotive force generated in the secondary coils 154a and 154b.

As another method of measuring speed using magnetism, Japanese Patent Application Laid-Open No. 8-21 proposed by the present inventors has been proposed.
No. 1084 publication. As shown in FIG. 29, an exciting winding 203b is wound around the center leg 204b with respect to an E-shaped core 202 which is symmetrical about the center leg 204b as shown in FIG. Are wound so as to detect magnetic fluxes in the same direction. It is arranged on the moving conductive measurement object 201 so that the open surface of the leg faces the target surface and each leg is arranged in parallel to the moving direction of the target surface.

Then, an alternating current is passed through the exciting winding to create an alternating magnetic field perpendicular to the conductor surface, and the output difference between the two detecting windings is detected. At this time, if the conductor 201 is stopped as shown in FIG. 30A, the magnetic field is symmetric with respect to the center leg, the outputs of the left and right detection windings are equal, and the difference is zero. . When the conductor moves, the magnetic field is distorted in accordance with the flow velocity as shown in FIG. 30 (b), a difference occurs in the magnetic flux at the positions of the windings at both ends, and the difference signal changes. The amount of change corresponds to the flow velocity of the target, and the flow velocity of the target can be measured from the amount of change. Also in this method,
The speed sensitivity changes due to lift-off.
In Japanese Patent Publication No. 11084, this lift-off is described in FIG.
As in the case of No. 1, detection and correction were performed using an eddy current distance meter 256 attached to the apparatus.

As another method of measuring the flow velocity by using magnetism, Japanese Patent Application No. 8-255 proposed by the present inventor has been proposed.
No. 861. As shown in FIG. 32, an excitation winding P wound around a ceramic pipe 2 is arranged on a moving conductive measurement target object so that its central axis is perpendicular to the target surface. Two detection windings S ₁ and S ₂ wound in the same direction on a ceramic round bar 3 between the excitation winding P and the target surface, the center axis of which is parallel to the target surface and the moving direction of the target And the intermediate point between the _two detection windings S ₁ and S ₂ is arranged on the central axis of the excitation winding P. Here, a current is applied to the exciting winding P to excite a magnetic field in the measurement object, and the detection windings S ₁ and S ₂ detect the induction magnetic field Bv shown in FIG. 26A to measure the flow velocity. . Further, in this method, the offset due to the eddy current magnetic field Be changes and the flow velocity sensitivity changes due to the change in lift-off.
In No. 861, lift-off is detected based on output voltages of two detection windings S ₃ and S ₄ wound so as to detect a magnetic field component perpendicular to a target surface above and below an exciter as shown in FIG. And the change in flow rate sensitivity were corrected.

[0013]

However, Japanese Patent Application Laid-Open Nos. Hei 2-31766, Hei 5-297012, Hei 8-211084, and Japanese Patent Application No. Hei 8-25110 are conventional.
In the flow velocity measuring method / apparatus of the type that excites a magnetic field such as No. 5861, detects a velocity induced magnetic field, and calculates a flow velocity from the detected magnetic field, when an AC magnetic field is used as the exciting magnetic field as described above, the detection is performed. The apparatus detects the eddy current magnetic field Be generated from the target, and the offset of the flow velocity signal changes. This change is uniquely determined by lift-off if the target surface is flat.
The lift-off can be separately detected and corrected like the signal. However, when the target surface is not flat and has undulations, the target surface is tilted when viewed locally as shown in FIG.
Due to this inclination, the eddy current magnetic field Be is inclined. Therefore, even in a method for detecting a magnetic field component in the vertical direction as disclosed in JP-A-5-297012 and JP-A-8-211084,
JP-A-2-31766 and JP-A-8-2558
Even in the method of detecting a horizontal magnetic field component such as No. 61, even if the lift-off is constant, the inclination of the target surface under the device changes with the movement or change of the wave, so the detection is performed by the detection device. Since the magnitude of the eddy current magnetic field Be changes and the offset changes, there is a problem that an offset change that cannot be completely removed even if lift-off is detected and corrected remains, causing a measurement error. .

[0014]

According to a first aspect of the present invention, there is provided a method for measuring a flow velocity, wherein a magnetic field perpendicular to the surface of a moving conductive measuring object is excited, and the surface of the measuring object and its movement are moved. Detecting a magnetic field in a direction parallel to the direction in one or more ranges, and calculating the flow speed of the measurement object based on the magnetic field signal detected in the one or more ranges; In one or more ranges that do not coincide with the magnetic field detection range, a magnetic field in a direction parallel to the moving direction of the measurement object is detected, and information on the inclination of the surface of the measurement object is detected based on the detected magnetic field signal. And corrects the calculated flow velocity of the measurement object based on the information.

According to a second aspect of the present invention, there is provided a flow velocity measuring method comprising:
2. The flow velocity measuring method according to claim 1, wherein an axis perpendicular to a surface to be measured, in which the exciting magnetic field is line-symmetric, in a plane parallel to a moving direction of the object to be measured and perpendicular to a surface of the object to be measured. Select, the detection range of the magnetic field for calculating the flow velocity, a range of a predetermined length in a direction parallel to the moving direction of the measurement object around the point on the vertical axis,
The detection range of the magnetic field for correcting the flow velocity is set to a first range in which the excitation magnetic field is line-symmetric with respect to the vertical axis in the plane.
And the center of each of the second points, each having a range of equal length in a direction parallel to the moving direction of the measurement object, and the distance from the vertical axis to each of the first and second points is The detection range of the magnetic field for calculating the flow velocity is set to be greater than the distance from the perpendicular axis to the center position of each of the two divided ranges.

According to a third aspect of the present invention, there is provided a flow velocity measuring method comprising:
2. The flow velocity measuring method according to claim 1, wherein an axis perpendicular to a surface to be measured, in which the exciting magnetic field is line-symmetric, in a plane parallel to a moving direction of the object to be measured and perpendicular to a surface of the object to be measured. And the detection range of the magnetic field for calculating the flow velocity is measured on the first and second points where the excitation magnetic field is line-symmetric with respect to the vertical axis in the plane. The range of the same length in the direction parallel to the moving direction of the object, respectively, the detection range of the magnetic field for correcting the flow velocity, the distance from the vertical axis is more than the first and second points, respectively. Distant, third and fourth points at which the exciting magnetic field is line-symmetric with respect to the vertical axis in the plane, and having equal lengths in directions parallel to the moving direction of the measurement object. Range.

According to a fourth aspect of the present invention, there is provided a flow velocity measuring method comprising:
2. The flow velocity measuring method according to claim 1, wherein an axis perpendicular to a surface to be measured, in which the exciting magnetic field is line-symmetric, in a plane parallel to a moving direction of the object to be measured and perpendicular to a surface of the object to be measured. And the detection range of the magnetic field for calculating the flow velocity is measured on the first and second points where the excitation magnetic field is line-symmetric with respect to the vertical axis in the plane. The ranges of the same length in the direction parallel to the moving direction of the object are respectively equal, and the detection range of the magnetic field for correcting the flow velocity is parallel to the moving direction of the measuring object around the point on the vertical axis. The distance from the vertical axis to the center position of each of the two ranges obtained by dividing the magnetic field detection range for correcting the flow velocity from the vertical axis to the first position is defined as the first length from the vertical axis. And the distance to each second point, It is intended to hear.

According to a fifth aspect of the present invention, there is provided a flow velocity measuring method comprising:
2. The flow velocity measuring method according to claim 1, wherein an axis perpendicular to a surface to be measured, in which the exciting magnetic field is line-symmetric, in a plane parallel to a moving direction of the object to be measured and perpendicular to a surface of the object to be measured. Is selected, and the magnetic field detection range for calculating the flow velocity is a range of a predetermined length in a direction parallel to the moving direction of the measurement object around the point on the vertical axis, and the flow velocity correction is performed. The detection range of the magnetic field for performing, the center on the point on the vertical axis, than the detection range of the magnetic field for calculating the flow velocity, the length in the direction parallel to the moving direction of the measurement target, It is a long range.

According to a sixth aspect of the present invention, there is provided a flow velocity measuring method comprising:
In the flow velocity measuring method according to any one of claims 1 to 5, the entirety of the detection range of the magnetic field for calculating the flow velocity and the detection range of the magnetic field for correcting the flow velocity may be the measurement target surface. Are provided on a straight line that intersects an axis perpendicular to the axis and is parallel to the moving direction of the measurement object.

According to a seventh aspect of the present invention, there is provided a flow velocity measuring method comprising:
The flow velocity measuring method according to any one of claims 1 to 6, wherein a detection range of a magnetic field for calculating the flow velocity is near a center axis of the excitation magnetic field, and a magnetic field for correcting the flow velocity. Is a range in which the amount of change in the magnetic field with respect to the flow velocity of the object to be measured is minimized.

[0021] The flow velocity measuring device according to claim 8 of the present invention comprises:
Exciting means arranged to apply a magnetic field perpendicular to the surface of the moving conductive measurement object, and arranged to detect a magnetic field in a direction parallel to the surface of the measurement object and the moving direction thereof. A flow rate measuring device comprising: at least one magnetic field detecting means; and measuring means for calculating a flow velocity of the object to be measured based on a magnetic field signal detected by the one or more magnetic field detecting means. At a position different from the position, one or more sub-magnetic field detecting means arranged to detect a magnetic field in a direction parallel to the moving direction of the measurement object;
Based on the magnetic field signal detected by the one or more sub-magnetic field detecting means, information on the inclination of the surface of the measuring object is obtained, and the flow rate of the measuring object calculated by the measuring means is corrected based on the information. Correction means.

According to a ninth aspect of the present invention, there is provided a flow velocity measuring device comprising:
9. The flow velocity measuring apparatus according to claim 8, wherein an axis perpendicular to a surface to be measured, in which the exciting magnetic field is line-symmetric, in a plane parallel to a moving direction of the object to be measured and perpendicular to a surface of the object to be measured. The magnetic field detecting means for calculating the flow velocity is arranged on the vertical axis as one, and detects a magnetic field over a range of a predetermined length in a direction parallel to the moving direction of the measurement object. And two auxiliary magnetic field detecting means for correcting the flow velocity are disposed on each of the first and second points in the plane where the exciting magnetic field is line-symmetric with respect to the vertical axis. Further, each sub-magnetic field detecting means detects a magnetic field over a range of the same length in a direction parallel to the moving direction of the measurement object, and detects a distance from the vertical axis to each of the first and second points. Calculates the flow velocity from the vertical axis Than the distance to the center position of the detection range bisecting the respective ranges of the magnetic field of the order is obtained by the respectively larger.

According to a tenth aspect of the present invention, there is provided a flow velocity measuring device according to the eighth aspect, wherein the flow velocity measuring device is arranged in a plane parallel to a moving direction of the measuring object and perpendicular to a surface of the measuring object. The magnetic field detecting means for selecting an axis perpendicular to the measurement target surface in which the exciting magnetic field is line-symmetric and calculating the flow velocity has two exciting magnetic fields with respect to the perpendicular axis in the plane. A magnetic field arranged on each of the first and second points that are axisymmetrical, and detecting a magnetic field over a range of equal lengths in a direction parallel to the moving direction of the measurement object, to correct the flow velocity. The sub-magnetic field detecting means is configured such that the exciting magnetic field is line-symmetric with respect to the vertical axis in the plane, the distance from the vertical axis being farther than the first and second points, respectively. Third and fourth
And each sub-magnetic field detection means detects a magnetic field over a range of equal length in a direction parallel to the moving direction of the measurement object.

The flow velocity measuring device according to an eleventh aspect of the present invention is the flow velocity measuring device according to the eighth aspect, wherein in the plane parallel to the moving direction of the measurement object and perpendicular to the surface of the measurement object, The magnetic field detecting means for selecting an axis perpendicular to the measurement target surface in which the exciting magnetic field is line-symmetric and calculating the flow velocity has two exciting magnetic fields with respect to the perpendicular axis in the plane. A magnetic field arranged on each of the first and second points that are axisymmetrical, and detecting a magnetic field over a range of equal lengths in a direction parallel to the moving direction of the measurement object, to correct the flow velocity. The sub-magnetic field detection means is arranged as one on the vertical axis, and detects a magnetic field over a range of a predetermined length in a direction parallel to the moving direction of the measurement target, and further detects the magnetic field from the vertical axis. Correct flow velocity The distance to the center position of each of the two divided ranges of the magnetic field for detection is larger than the distance from the vertical axis to each of the first and second points. is there.

A flow velocity measuring apparatus according to a twelfth aspect of the present invention is the flow velocity measuring apparatus according to the eighth aspect, wherein the flow velocity measuring apparatus is arranged such that the plane is parallel to a moving direction of the object and perpendicular to a surface of the object. The magnetic field detecting means for selecting an axis perpendicular to the measurement target surface where the excitation magnetic field is axisymmetric and calculating the flow velocity is disposed on the vertical axis as one, and moving the measurement target object. The magnetic field over a range of a predetermined length in a direction parallel to the direction is detected, and the sub-magnetic field detecting means for correcting the flow velocity is disposed on the vertical axis as one, and calculates the flow velocity. In this case, the magnetic field is detected over a range in which the length in the direction parallel to the moving direction of the measurement object is longer than the detection range of the magnetic field detecting means.

According to a thirteenth aspect of the present invention, in the flow velocity measuring apparatus according to any one of the eighth to twelfth aspects, all of the magnetic field detecting means and the sub-magnetic field detecting means are provided with the same. It is arranged on a straight line that intersects an axis perpendicular to the measurement target surface and is parallel to the moving direction of the measurement target.

[0027] According to a fourteenth aspect of the present invention, in the flow velocity measuring device according to any one of the eighth to thirteenth aspects, the detection range of the magnetic field detecting means is set at a center of the excitation magnetic field. The vicinity of the axis is set, and the detection range of the sub-magnetic field detection means is set to a range in which the amount of change in the magnetic field with respect to the flow velocity of the measurement object is the smallest.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing the embodiments of the present invention, the operating principle of the flow velocity measuring method and apparatus of the present invention will be described first. (1) Principle of flow velocity measurement Here, a case where a sensor head as shown in FIG. 3 is used as a base flow velocity measurement apparatus will be described. In this sensor head, as shown in FIG. 3, one excitation winding P is arranged on a conductive measurement object moving as an excitation device so that its central axis is perpendicular to the object surface, As a detection device for detection, two detection windings S ₁ and S ₂ are arranged between the excitation winding P and the target surface so that the central axes thereof are parallel to the target surface and the moving direction of the target, and the two detection windings are parallel to each other. Lines S ₁ and S ₂
Are arranged so that the intermediate point of the center line is located on the central axis of the exciting winding P. These S ₁ and S ₂ are hereinafter referred to as detection windings for detecting the flow velocity.

Here, an AC exciting current is supplied to the exciting winding P to excite a magnetic field perpendicular to the target surface. Then, an induced magnetic field Bv is generated due to the speed effect described above. The induction magnetic field Bv is parallel to the target surface at the position of the detection winding immediately below the exciting winding P as shown in FIG. 5, and this detection magnetic field Bv is connected to two detection windings S ₁ arranged in parallel to the target surface. is detected by taking the sum signal S _2. Since the detected Bv corresponds to the flow velocity of the target, the flow velocity of the target can be measured from this. Actually, the output signals of the detection windings S ₁ and S ₂ are
Using a lock-in amplifier or the like, a component having a phase shifted by -90 ° from the excitation current is detected and used as a flow velocity source signal which is a source of flow velocity measurement (original magnetic field, ie, a magnetic field component having the same phase as the excitation current is detected. However, in this case, the detection winding is used for detecting the magnetic field, and since the magnetic field detected by the detection winding and the detection voltage of the detection winding have a phase difference of −90 °, the phase component shifted by −90 ° is used. Detection).

(2) Countermeasures for Influence of Rippling When the target surface under the apparatus is tilted due to the rippling, as described above, the offset of the flow velocity original signal which is the output signal of the detection windings S ₁ and S ₂ for detecting the flow velocity is used. Changes, and accurate flow velocity measurement becomes impossible. Therefore, as shown in FIG. 3, the detection windings S ₃ and S ₄ are newly added so that the central axes thereof are the same as the central axes of the detection windings S ₁ and S ₂ for detecting the flow velocity, and the central axis of the excitation device is changed. Are arranged close to the outside of S ₁ and S ₂ at positions symmetrical with respect to the center (corresponding to claims 1 to 6 and 8 to 13). And the sum signal of the detection windings S ₃ and S ₄ is
Similarly to S ₁ and S ₂ , a component having a phase shifted by −90 ° from the exciting current is detected by using a lock-in amplifier or the like.

[0031] In this new detection winding S _3, S ₄ are the in position close to the detection winding S _1, S ₂ for flow rate detection, and detects the magnetic field in the same direction as the S _1, S _2, The influence of the change of the eddy current magnetic field Be due to the inclination of the target surface is almost the same as that of S ₁ and S ₂ . Therefore, from the sum signal of S ₃ and S ₄ , S
_1, S can be calculated the change in the offset due to tilt of the _second sum signal, that the flow velocity based signal, it is possible to correct the change in the offset due to tilt (corrected method FIGS. 8, 9 and 12 , 13). This S ₃ ,
Corresponds to a S ₄ in the detection coil S _1, S ₂ for flow rate detection, detection winding for tilt detection, it referred to as a source signal tilt signals after detection of the sum signal.

FIG. 8 shows how the flow velocity original signal and the inclination original signal change with respect to the inclination of the target surface of the sensor head of FIG.
Here, an SUS316 plate as shown in FIG. 6 was used as a measurement target, and a test of tilting the plate was performed. As a result of the test, both the flow velocity original signal (S ₁ + S ₂ ) shown by the solid line and the gradient original signal (S ₃ + S ₄ ) shown by the broken line in FIG.

Therefore, assuming that the gradient of the gradient-flow rate original signal characteristic line (gradient of the characteristic line) in FIG. 8 is Af and the gradient of the gradient-gradient original signal characteristic line (gradient of the characteristic line) is As, the following (2) It is understood that the influence of the inclination can be corrected by using the coefficient α determined by the expression (3) and by using the expression (3). α = Af / As (2) (signal after inclination correction) = (flow velocity original signal) −α · (tilt original signal) (3) In FIG. 8, even if the inclination is 0, each signal is not 0. But,
This is because even if the inclination of the target surface is 0, the eddy current magnetic field Be is generated from the target, and this is the offset amount.
The offset at the inclination of 0 is uniquely determined by the lift-off with respect to the target surface, and the lift-off can be detected and corrected by any method as in Japanese Patent Application No. 8-2555861.

(3) Optimal position of detection winding for detecting inclination As described in (2) above, detection winding S for detecting inclination
_3, the S ₄ and the detection winding S _1, S ₂ for flow rate detection, but characteristics for an eddy current magnetic field Be is almost the same, likewise becomes substantially similar characteristics are also to induce the magnetic field Bv by the speed effect If the slope original signal is subtracted by multiplying the flow velocity original signal by an appropriate coefficient, the influence of the inclination of the target surface can be corrected, but the magnitude of the signal with respect to the flow velocity also decreases. FIG. 9 shows how the flow velocity original signal and the gradient original signal change with respect to the target flow velocity. Here, as shown in FIG. 7, a disk made of SUS316 was rotated, and the sensor head of the present apparatus was disposed thereon to measure each signal. FIG. 7A is a view of the test apparatus as viewed from the front, and FIG. 7B is a view of the test apparatus as viewed from directly above. As a result of the test using the test device of FIG.
The flow velocity original signal (S ₁ + S ₂ ) shown by the solid line and the gradient original signal (S ₃ + S ₄ ) shown by the dashed line in FIG. 9 both show that the change with respect to the target flow velocity is almost linear, and that the characteristics of both are almost equal. I understand.

Then, the gradient of the flow velocity-flow velocity original signal characteristic line (gradient of the characteristic line) in FIG. 8 is Bf, the gradient of the flow velocity-gradient original signal characteristic line (gradient of the characteristic line) is Bs, and the coefficient β is Equation (4), β = Bf / Bs (4) Also, when the coefficient k is expressed by the following equations (5) and (6), k = 1 / (1−α / β) (5) = 1 / (1−Af / As · Bs / Bf) (6) According to the above equation (3) (signal for flow velocity after inclination correction)
Is reduced to 1 / k as compared to before the correction. For example, in the case of the apparatus having the characteristics shown in FIGS. 8 and 9, the signal for the flow velocity after the inclination correction is attenuated to about 1/15 of that before the correction.

Therefore, here, the position of the detection winding for inclination correction and the position of the detection winding for flow velocity detection are changed to try to reduce the reduction rate of the flow velocity signal. Now, as shown in FIG. 10, the position of one detection winding is set in a direction parallel to the direction of the flow velocity (X
Direction, X = 0 is a point on the central axis of the exciting winding), and the gradient (gradient of the characteristic straight line) B (corresponding to Bf and Bs) and the gradient of the flow velocity characteristic straight line in the output signal of the detecting winding. The state of the change in the gradient of the characteristic line (the gradient of the characteristic line) A (corresponding to Af and As) is examined, and the result is shown in FIG. 11 (in FIG. 11, normalized by the value of X = 0 mm). The measurement target in FIG. 10 was a SUS plate in the case of the inclination characteristic, and a SUS disk in the case of the flow velocity characteristic.

The following can be understood from the results shown in FIGS. (A) The gradient B of the flow velocity characteristic straight line is maximum near the central axis of the exciting magnetic field. That is, the flow velocity sensitivity is maximum near the central axis. (B) Both the gradient B of the flow-rate characteristic line and the gradient A of the gradient characteristic line decrease as the distance from the center axis of the exciting winding increases, but the attenuation rate of the gradient B of the flow-rate characteristic line becomes smaller. And becomes 0 at a point closer to the exciting winding center axis than A. Therefore, at the point where B = 0 (that is, the position where the amount of change in the magnetic field with respect to the flow velocity of the target becomes minimum)
If the inclination detecting winding is arranged, k = 1 from the equation (6), and the inclination can be corrected without lowering the flow velocity sensitivity.

From the above, it has been found that the optimum position of each detection winding is as follows (corresponding to claims 7 and 14). (A) a detection winding for detecting the flow velocity: a position as close as possible to the center axis of the exciting magnetic field; (b) a detection winding for detecting the inclination: a position where the gradient B of the flow velocity characteristic line becomes zero. The arrangement is, for example, as shown in FIG. 2. FIGS. 12 and 13 show how the flow velocity original signal and the inclination original signal change with respect to the inclination of the target surface and how the flow velocity changes with respect to the target surface in this case, respectively. .

(4) Correction of Lift-off Fluctuation When the distance (ie, lift-off) between the flow velocity detection position of the sensor head of the present apparatus and the surface to be measured changes, the inclination 0 included in the signal after the influence of the inclination is corrected. The offset amount uniquely determined by the lift-off changes, and the flow velocity sensitivity of the present apparatus also changes. In the embodiment described later, the influence of these lift-off fluctuations is detected and corrected. Here, a lift-off detection method and a lift-off fluctuation correction method will be briefly described. Here, similarly to Japanese Patent Application No. 8-2555861, the excitation winding P
The two detections are carried out so as to detect a magnetic field which is coaxial with the excitation winding P in a direction perpendicular to the target surface and in the same direction, respectively, at a position symmetrical with respect to the excitation winding P, and at a position symmetrical with respect to the excitation winding P. The windings S ₅ and S ₆ are arranged, and lift-off is detected from the difference signal. The detection winding S _5, S ₆ is referred to as a detection coil for lift-off detection below.

At this time, since the magnetic field is excited perpendicularly to the target surface by the excitation winding for measuring the flow velocity as shown in FIG. 5, the eddy current Je flowing through the target by the magnetic field causes the magnetic field perpendicular to the target surface. An eddy current magnetic field Be is generated. Since the eddy current magnetic field Be changes depending on the distance to the target surface, if the eddy current magnetic field is detected by the detection windings S ₅ and S ₆ , the distance to the target surface, that is, the lift-off can be detected. Furthermore, when the lift-off is changed, the lift-off-offset characteristic, which is how the offset uniquely determined by the lift-off at the slope of 0, and the lift-off-flow velocity sensitivity, which is how the flow velocity sensitivity changes, are determined in advance. The influence of the lift-off fluctuation is corrected by using the lift-off signal detected based on this characteristic beforehand measured. Now that the description of the operation principle of the flow velocity measuring method and apparatus of the present invention has been completed, an embodiment of the present invention will be described next.

Embodiment 1 FIG. 1 is a configuration diagram of a flow velocity measuring apparatus according to Embodiment 1 of the present invention. The illustrated apparatus has a sensor head 1 having a configuration as shown in FIG.
And a speed measurement circuit 30, a tilt detection circuit 40, a lift-off measurement circuit 50, and a correction circuit 70.

As shown in FIG. 2, the sensor head 1 is an excitation winding wound on a ceramic round pipe 2 on a moving conductive measuring object such that the center axis thereof is perpendicular to the object surface. P, a ceramic round bar 3 is arranged between the exciting winding P and the target surface such that the center axis thereof is parallel to the target surface and the moving direction of the target. In a position symmetrical about the center axis of the exciting winding P, 2
Winding _two detection windings S ₁ and S ₂ for flow velocity detection,
Further, two detection windings S ₃ and S ₄ for detecting inclination, and an excitation winding P are further wound outside the round pipe 2 made of ceramics at positions symmetrical about the center axis of the excitation winding. For the round pipe 2 made of ceramics, one detection winding S ₅ for lift-off detection, one between the exciting winding P and the target, and one at a position symmetrical with the exciting winding P and the exciting winding P. in which wound S _6. In the case of the apparatus used here, the position of the detection winding for detecting the inclination in FIG. 2 is almost the optimum position, and the gradient B of the flow velocity characteristic straight line is almost 0 at the positions of S ₃ and S _4. Become.

The flow velocity measuring circuit 30 comprises an exciting circuit 10 and a detecting circuit 20, as shown in FIG. The excitation circuit 10 includes an oscillator 11 and a constant current amplifier 12. The detection circuit 20 includes a bridge circuit 21, a band pass filter 22, and a lock-in amplifier 23. The excitation circuit 10 supplies a current to the excitation winding P to excite a magnetic field in the measurement target. Therefore, a sine wave of 1 Hz to 1 kHz is generated by the oscillator 11, and an exciting current is supplied to the exciting winding P via the constant current amplifier 12. Here, the excitation frequency was set to 70 Hz.

Output signals from the detection windings S ₁ and S ₂ for flow velocity detection enter a detection circuit 20. Here, the two signals from the two detection windings are first added by the bridge circuit 21, and the sum signal is calculated. The bridge circuit 21 is adjusted in advance so that its output signal becomes zero in a state where there is no magnetic or conductive thing or anything that generates an electromagnetic field around the sensor head. By doing so, the bridge circuit 21 can be adjusted so as to cancel unnecessary excitation magnetic field signals detected by the _two detection windings S ₁ and S ₂ . The signal after the adjustment is supplied to the excitation circuit 10
After the noise signal in the unnecessary band is removed in advance by the band-pass filter 22 having a predetermined bandwidth with the center frequency of the exciting current of, the lock-in amplifier 23 shifts the exciting current of the exciting circuit 10 by −90 °. The phase component is detected. This reference phase signal for detection (re
f) is supplied from the oscillator 11 to the lock-in amplifier 23. The signal after the detection by the lock-in amplifier 23 is the flow velocity original signal which is the basis of the flow velocity measurement.

The output signals from the detection windings S ₃ and S ₄ for detecting the inclination enter the inclination detection circuit 40. The inclination detection circuit 40 includes a bridge circuit 41, a band-pass filter 42, and a lock-in amplifier 43. Here, the two signals from the two detection windings S ₃ and S ₄ are first added by the bridge circuit 41, and the sum signal is calculated. This bridge circuit 41
Is magnetic or conductive around the sensor head,
Or, in a state where no electromagnetic field is generated, the output signal is previously adjusted so as to become zero. The signal after this adjustment has the frequency of the exciting current of the exciting circuit 10 as a center frequency, and after removing a noise signal in an unnecessary band in advance by a band-pass filter 42 having a predetermined bandwidth,
The lock-in amplifier 43 detects a component having a phase shifted by −90 ° with respect to the exciting current of the exciting circuit 10. This reference phase signal for detection is supplied from the oscillator 11 to the lock-in amplifier 43. The signal after detection by the lock-in amplifier 43 is a slope original signal that serves as a slope correction source.

The detection windings S ₅ , S ₅ for lift-off detection
The output signal from ₆ enters the lift-off measurement circuit 50.
The lift-off measurement circuit 50 includes a bridge circuit 51, a band-pass filter 52, and a lock-in amplifier 53.
Here, the signals from the two detection windings S ₅ and S ₆ are first subtracted by the bridge circuit 51 to calculate a difference signal. This bridge circuit 51 is adjusted in advance so that its output signal becomes zero in a state where there is no magnetic or conductive thing or anything that generates an electromagnetic field around the sensor head. The signal after the adjustment has the frequency of the exciting current of the exciting circuit 10 as a center frequency, and after removing a noise signal in advance by a band-pass filter 52 having a predetermined bandwidth, the lock-in amplifier 53 converts the signal into an exciting current of the exciting circuit 10. On the other hand, a component having a phase shifted by -180 ° is detected (originally, an exciting magnetic field, that is, a magnetic field component shifted by −90 ° from the exciting current is detected. Here, a detection winding is used for detecting the magnetic field. Since the detection voltage of the detection winding has a phase difference of −90 °, a phase component shifted by −180 ° is detected). The reference phase signal for detection is supplied from the oscillator 11 to the lock-in amplifier 53. The signal detected by the lock-in amplifier 53 is a lift-off source signal that is a source of lift-off correction.

After that, the flow velocity original signal which is the output signal of the flow velocity measuring circuit 30, the inclination original signal which is the output signal of the inclination detecting circuit 40, and the lift-off original signal which is the output signal of the lift-off measuring circuit 50 are corrected by the correction circuit 70. to go into. This correction circuit 70 includes an A / D converter 71, a computer 72, and a D
/ A converter 73. In the correction circuit 70, first, A /
The flow velocity original signal, the inclination original signal, and the lift-off original signal are respectively A / D-converted by the D-converter 71 and are taken into the computer 72. The following processing is performed by the computer 72.
Performed by software above. (1) On the computer, first, the lift-off is calculated from the lift-off source signal. Here, the state of the change of the lift-off source signal when the lift-off is changed is measured in advance, and the lift-off is calculated from the lift-off source signal based on the lift-off-lift-off source signal characteristic curve.

(2) Next, the slope original signal is multiplied by a coefficient α and subtracted from the flow velocity original signal as shown in equation (3) to correct the influence of the slope. Here, since the coefficient α generally changes due to lift-off, a slope characteristic as shown in FIGS. 8 and 12 is acquired in advance for each lift-off, and is then obtained using the equation (2). (3) Subsequently, the lift-off fluctuation of the signal after the influence of the inclination is removed is corrected. Here, first, based on the lift-off previously calculated, an offset by the eddy current magnetic field Be is calculated,
This is subtracted from the signal after the influence of the inclination is removed. Here, the state of change of the offset included in the signal after the inclination correction when the lift-off is changed is measured in advance, and the offset is calculated from the lift-off based on the lift-off-offset characteristic curve.

(4) Next, the flow velocity sensitivity change accompanying the change of the lift-off is corrected from the signal from which the offset is subtracted to obtain a final flow velocity value. Here, the state of the flow velocity sensitivity of the signal after inclination correction when the lift-off is changed (the amount of change in the signal after inclination correction when the target flow velocity is 0 m / sec and 1 m / sec) is measured in advance. Based on the lift-off-flow velocity sensitivity characteristic curve, the flow velocity sensitivity at the lift-off is calculated, and the signal after subtracting the offset is divided by the calculated flow velocity sensitivity to obtain a final flow velocity value.

In the first embodiment, the sensor head for measuring the flow velocity has a structure as shown in FIGS. 2 and 3 (that is, the number of elements of the magnetic field detection winding is determined by the number of the magnetic flux detection windings S ₁ and S ₂ ). 2
One, 2 Tsutoshi skew detection winding S _3, S _4, the S ₁
While all to S ₄ were the moving direction and configuration of those arranged in parallel colinear) with a description of the measurement object, it is possible to realize a number of sensor head by other structure. The essence of the present invention is to detect the flow velocity by a detection device that detects a magnetic field in a direction parallel to the flow velocity of the target, and to tilt the inclination by a detection device that detects a magnetic field in a direction parallel to the flow velocity of the target at another position. This is the point of detection and correction, and includes various forms that satisfy this condition.

For example, each of FIGS.
As shown in (c) and (d), only one detection winding for detecting the flow velocity is used (S _{1 in the} drawing), or only one detection winding for detecting the inclination is used (S _{3 in the} drawing). Or the same function as that of the first embodiment can be obtained by using both one of the flow velocity detection winding and the inclination detection winding. , 12). If only one winding for flow velocity detection and one winding for inclination detection are used, the output signal of each detection winding can be directly input to a lock-in amplifier and detected without passing through a bridge circuit. Good. When a long winding is used as shown in FIG. 14 (c), for example, the average value of the magnetic field over its entire length is detected. The output of the winding corresponds approximately to the magnitude of the magnetic field at the center of the winding. When the detection winding crosses the excitation magnetic field central axis, the detection winding is divided into two on the excitation magnetic field central axis, and an output signal corresponding to a value obtained by adding the magnitudes of the magnetic fields at the respective center positions is obtained. can get.

As shown in FIGS. 14 (c) and 14 (d) and FIGS. 15 (c) and 15 (d), the detection winding for detecting the flow velocity is wound on the detection winding for detecting the inclination. It doesn't matter. Even if there are two or more detection windings for flow velocity detection and inclination detection, the sum signal of each winding may be obtained. FIG.
As shown in FIGS. 17 and 19, the detection winding for detecting the inclination may be arranged inside the ceramic round pipe instead of outside, and adjacent to the detection winding for detecting the flow velocity. Also, as shown in FIGS. 16 to 19, the detection winding for detecting the flow velocity and the detection winding for detecting the inclination may be wound separately, instead of being wound around a coaxial round bar. The heights of the two from the target surface may be different.
Further, in all cases, the detection winding for detecting the flow velocity and the detection winding for detecting the inclination may be arranged reversely. However, as is apparent from the correction expression of the expression (3), Only the detection winding for detecting the flow velocity is used as the detection winding for detecting the inclination, and the detection winding for detecting the inclination is used as the detection winding for detecting the flow velocity.

Another essence of the present invention is that the magnetic field detecting device for detecting the inclination is separated from the magnetic field detecting device for detecting the flow velocity along the direction parallel to the moving direction of the target from the central axis of the exciting magnetic field. (Corresponding to claims 7 and 14). For example, as shown in FIG. 14A, when there are two detection windings for detecting the inclination and two detection windings for detecting the flow velocity, the detection windings S ₃ and S ₄ for detecting the inclination are used. The distance from the excitation magnetic field center axis is the center position of the detection windings S ₁ and S ₂ for detecting the flow velocity.
It may be far away so that it is longer than the center position of.
In addition, as shown in FIG.
One, if the detection winding for flow rate detection is one, taking longer than the detection winding lines S ₁ of the length of the detection winding S ₃ for tilt detection (horizontal length in the figure) for the flow rate detection Good. In this case, since both detection windings straddle the center axis of the excitation magnetic field,
As described above, both detection windings may be divided into two parts by the center axis of the excitation magnetic field.
Is almost the same as (e) in the figure, so that the magnetic field detecting device for detecting the tilt is located at a position farther from the center axis of the exciting magnetic field than the magnetic field detecting device for detecting the flow velocity. 16 to 19, the detection winding for detecting the flow velocity and the detection winding for detecting the inclination are wound on separate ceramic round bars, respectively, at different positions from the surface to be measured. The ceramic rods were arranged horizontally with respect to the surface to be measured so that their heights from the surface to be measured were the same, and their central axes were parallel to the direction of flow velocity. (Arranged horizontally on the back).

Embodiments classified according to the number of elements of the magnetic field detecting winding and the arrangement thereof from among the many examples of the configuration of the sensor head shown in FIGS. 14 to 19 will be described below. In the embodiment classified according to the configuration of the sensor head,
A part overlapping with the above description is also included. Embodiment 2 Embodiment 2 is, for example, shown in FIG. 14 (b), FIG. 15 (b), FIG. 16 (b), FIG. 17 (b), FIG. 18 (b), or FIG. as shown in), the flow rate detection winding is 1 Tsutoshi of S _1, the inclination detecting winding is S _3, configuration of the 2 Tsutosuru sensor heads S ₄ provided on both sides of the S ₁ (according (Corresponds to items 2 and 9). The arrangement of the detection windings and the detection range in the second embodiment are as follows. First, in a plane parallel to the moving direction of the measurement target and perpendicular to the surface of the measurement target, an axis perpendicular to the measurement target surface where the excitation magnetic field by the excitation winding P is line-symmetric is selected, and a single axis is selected. The flow rate detecting winding S ₁ is arranged on the vertical axis, and detects a magnetic field over a range of a predetermined length in a direction parallel to the moving direction of the object to be measured. S ₃ and S ₄ are arranged on the first and second points where the exciting magnetic field is line-symmetric with respect to the vertical axis in the plane, and further, the respective inclination detecting windings S ₃ and S ₄ Detects a magnetic field over a range of equal length in a direction parallel to the direction of movement of the measurement object, and the distance from the vertical axis to each of the first and second points is greater than the distance from the vertical axis to the first and second points. The detection range of the magnetic field for calculating the flow velocity is divided into two equal parts. So that each larger than away.

Embodiment 3 Embodiment 3 is, for example, FIG.
FIG. 15A, FIG. 16A, and FIG.
7 (a), as shown in (a) of (a), or 19 in FIG. 18, 2 Tsutoshi, skew detection winding of the flow rate detection winding S _1, S ₂ is S ₁ , S ₃ provided on both sides of S _2,
It is a structure of 2 Tsutosuru sensor heads S ₄ (corresponding to claim 3, 10). The arrangement of each detection winding and the detection range thereof in the third embodiment are as follows. First, in a plane parallel to the moving direction of the object to be measured and perpendicular to the surface of the object to be measured, an axis perpendicular to the surface to be measured in which the exciting magnetic field generated by the exciting winding P is axisymmetric is selected. The flow velocity detecting windings S ₁ and S ₂ are respectively arranged on first and second points where the exciting magnetic field is line-symmetric with respect to the vertical axis in the plane, and the movement of the measurement object is performed. To detect magnetic fields over an equal length range in a direction parallel to the direction, and the two inclination detecting windings S ₃ and S ₄ are arranged such that the distance from the vertical axis is equal to the first and second distances. Excitation magnetic fields are disposed on third and fourth points in the plane, which are farther from the point and are line-symmetric with respect to the vertical axis in the plane, and each of the inclination detecting windings S ₃ , S ₄ Detects a magnetic field over a range of equal length in a direction parallel to the direction of movement of the measuring object. To be in.

Fourth Embodiment A fourth embodiment is, for example, shown in FIG. 14 (c), FIG. 15 (c), FIG. 16 (c), FIG. 17 (c), FIG. 18 (c), or FIG. As shown in (c), the number of windings for detecting the flow velocity is _two , S ₁ and S ₂ , and the number of windings for detecting the inclination is the direction of movement of the measuring object more than the detection range including S ₁ and S _2. 1 of Tsutosuru sensor head structure S ₃ having a long detection range in a direction parallel to the (corresponding to claim 4, 11). The arrangement of the detection windings and the detection range in the fourth embodiment are as follows. First, in a plane parallel to the moving direction of the object to be measured and perpendicular to the surface of the object to be measured, an axis perpendicular to the surface to be measured in which the exciting magnetic field generated by the exciting winding P is axisymmetric is selected. Windings S ₁ , S ₂
Are respectively arranged on the first and second points where the exciting magnetic field is line-symmetric with respect to the vertical axis in the plane, and have the same length in a direction parallel to the moving direction of the measurement object. And a single tilt detection winding S ₃ is arranged on the vertical axis,
Each and to detect the magnetic field over a range of a predetermined length in the direction parallel to the moving direction of the object to be measured, further the detection range of the magnetic field of the gradient detecting winding S ₃ from the vertical axis bisecting Is set to be larger than the distance from the vertical axis to each of the first and second points.

Embodiment 5 Embodiment 5 is, for example, shown in FIG. 14 (d), FIG. 15 (d), FIG. 16 (d), FIG. 17 (d), FIG. 18 (d), or FIG. as shown (d), the flow rate of the detection winding 1 Tsutoshi of S _1, the skew detection winding, S ₁
1 of Tsutosuru sensor head structure S ₃ having a long detection range in the moving direction parallel to the direction of the measurement object than the detection range of (corresponding to claim 5 and 12). The arrangement of the detection windings and the detection range thereof in the fifth embodiment are as follows. First, in a plane parallel to the moving direction of the object to be measured and perpendicular to the surface of the object to be measured, an axis perpendicular to the surface of the object to be measured in which the exciting magnetic field by the exciting winding P is axisymmetric is selected, and flow rate detection winding lines S ₁ of, placed on the vertical axis,
In addition, a magnetic field over a range of a predetermined length in a direction parallel to the moving direction of the measurement object is detected, and a single tilt detection winding S ₃ is also arranged on the vertical axis and used for flow velocity detection. than the magnetic field detection range of the winding S _1, the length in the direction parallel to the direction of movement of the measurement object, so as to detect a magnetic field over a long range.

Embodiment 6 Embodiment 6 includes, for example, FIGS. 14 (a) and 14 (b), (c), (d) which overlap with FIG. 2, and FIGS. 15 (a) and 15 which overlap with FIG. As shown in FIGS. 15 (b), (c), and (d), all the windings for detecting the flow velocity and the windings for detecting the inclination intersect with the axis perpendicular to the surface to be measured and perform the measurement. It is arranged on a straight line parallel to the moving direction of the object (corresponding to claims 6 and 13).

Embodiment 7 Embodiment 7 corresponds to FIG. 2 (a) or (b), FIG. 16 (a) or (b), or FIG.
(A) or (b), and as described in paragraphs [0037] and [0038], the magnetic field detection range of the flow detection windings S ₁ and S ₂ , or S ₁ ,
The magnetic field detection range of the inclination detecting windings S ₃ and S _{4 is set to} a range in which the amount of change in the magnetic field with respect to the flow velocity of the object to be measured is minimized, in the vicinity of the central axis of the exciting magnetic field by the exciting winding P. (Corresponding to claims 7 and 14).

Other Embodiments In the first embodiment, the diameters of the flow velocity detecting winding and the inclination detecting winding are the same, but they may have different diameters. Further, in the first embodiment, the air-core type in which the winding is wound around a ceramic bobbin is used as the detection device for detecting the flow velocity and the inclination is used, but the winding is wound around a magnetic material such as ferrite. A magnetic core type may be used. Further, other magnetic sensors such as a Hall element may be used instead of the detection winding as the magnetic detection means. Further, although the example in which the correction circuit 70 is processed by software on a computer is shown here, the processing may be performed by using hardware (for example, an appropriate analog circuit or the like) instead of software. In addition, although the lock-in amplifier is used here to detect the signal from each detection winding, the lock-in amplifier need not be used as long as the phase component desired for each signal can be detected. Instead, a synchronous detector or the like may be used.

Next, the flow velocity measuring apparatus according to the first embodiment (the sensor bed 1 having the configuration shown in FIG. 2, the flow velocity measuring circuit 30, the inclination detecting circuit 40, and the lift-off measuring circuit 50 shown in FIG. 1).
And a correction circuit 70) are shown. As a test device,
As shown in FIG. 20, a disk made of SUS316 was fixed diagonally to the rotating shaft, and the sensor head 1 of the present apparatus was disposed thereon, and a test simulating waving was performed. FIG. 20A is a view of the test apparatus as viewed from the front, and FIG. 20B is a view of the test apparatus as viewed from directly above. In this test, first, the apparatus is placed in a place where there is no magnetic, conductive or electromagnetic field around, and each of the bridge circuits 21 and 41 in the flow velocity measurement circuit 30, the inclination detection circuit 40 and the lift-off measurement circuit 50 And 51 are adjusted and then placed on the stopped SUS disk. Next, rotate the disc, stop the disc after a while,
The device was again removed from the SUS disk and placed in a place where there was no magnetic, conductive or electromagnetic field around.

FIG. 21 is a diagram showing an example of the confirmation test result of the wavy correction using the test apparatus of FIG. The horizontal axis in FIG. 21 is time (unit is seconds). FIG. 21A shows the speed of the measurement target obtained from the disk rotation speed.
(B) shows a value obtained by measuring the lift-off based on the ultrasonic distance meter. (C) of the figure shows a flow velocity original signal corresponding to the output signal of the detection winding for flow velocity detection.
(D) shows a tilt original signal which is an output signal of the tilt detection coil. FIG. 21 (e) shows the flow velocity value which is the final output of the apparatus after correcting the inclination of the measurement target surface and the lift-off fluctuation, and the waveforms of both (a) and (e) are almost the same. As described above, before the inclination correction, the flow velocity value greatly changes due to the change in the inclination of the target surface due to the wave. However, the change is eliminated by the inclination correction, and a high-accuracy flow velocity signal corresponding to the target velocity can be obtained. It can be seen that the speed can be detected stably.

FIG. 23 is a view showing another result of a confirmation test of correction of wavyness of the flow velocity measuring apparatus. Here, a low melting point alloy (wood metal) is melted and put into a long and thin container as shown in FIG. 22. So that the direction of flow velocity detection and the longitudinal direction of the container are parallel)
This device was placed on the low melting point alloy. Here, a plate was placed at one end of the container and moved to generate waves on the surface of the low melting point alloy. In this test, the flow rate of the low melting point alloy was zero. In this test, first, the apparatus is placed in a place where there is no magnetic, conductive or electromagnetic field around, and each of the bridge circuits 21 and 41 in the flow velocity measurement circuit 30, the inclination detection circuit 40 and the lift-off measurement circuit 50 And adjust 51,
Subsequently, the apparatus was placed on the low melting point alloy, and waves were generated by the plate. FIG. 23 shows only the state of signals from a state where the present apparatus is already arranged on a low melting point alloy.

FIG. 23A shows a value obtained by measuring the lift-off based on the ultrasonic range finder. Note that the horizontal axis in each figure indicates time (unit is seconds). FIG. 23 (b) shows a flow velocity original signal corresponding to an output signal of the detection winding for flow velocity detection, and FIG. 23 (c) shows a gradient original signal which is an output signal of the inclination detection coil. FIG. 23D shows the flow velocity value which is the final output of the apparatus after correcting the inclination of the measurement target surface and the lift-off fluctuation. As described above, before the inclination correction, the flow velocity value greatly changes due to the change in the inclination of the target surface due to the wave, but the change disappears due to the inclination correction,
The flow velocity signal corresponding to the target velocity is obtained, and it can be seen that the velocity can be detected stably.

[0065]

As described above, according to the present invention, the exciting means arranged to apply a magnetic field perpendicular to the surface of the moving conductive measuring object, the surface of the measuring object and its One or more magnetic field detecting means arranged to detect a magnetic field in a direction parallel to the moving direction, and a measurement for calculating a flow rate of the measurement object based on a magnetic field signal detected by the one or more magnetic field detecting means Means for detecting a magnetic field in a direction different from the detection position of the magnetic field detection means, in a direction parallel to the moving direction of the measurement object, and at least one sub-magnetic field arranged to detect the magnetic field Detecting means;
Based on the magnetic field signal detected by the one or more sub-magnetic field detecting means, information on the inclination of the surface of the measuring object is obtained, and the flow rate of the measuring object calculated by the measuring means is corrected based on the information. Since the correction means is provided, it is possible to stably measure the flow velocity even when the surface to be measured is wavy or the surface to be measured is inclined.

Further, according to the present invention, the detection range of the magnetic field detecting means for measuring the flow velocity is set near the central axis of the exciting magnetic field, and the detection range of the sub-magnetic field detecting means for obtaining information on the inclination. Is set to be in a range in which the amount of change in the magnetic field with respect to the flow velocity of the measurement object is minimized.
The inclination correction accuracy is good, and as a result, a flow velocity value with high accuracy can be obtained.

According to the present invention, the number of elements of the magnetic field detecting means for measuring the flow velocity is one or more, and the number of elements of the sub-magnetic field detecting means for obtaining the information on the inclination is one or more. As the number of elements can be combined to form a polymorphic sensor head, an appropriate type of sensor head can be selected and measured according to the type of the object to be measured. Range expanded.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a flow velocity measuring device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram (after optimization) of the sensor head of FIG. 1;

FIG. 3 is another configuration diagram (before optimization) of the sensor head according to the present invention.

FIG. 4 is an explanatory diagram of a ripple effect of a measurement target.

FIG. 5 is a diagram illustrating the principle of flow rate and lift-off detection.

FIG. 6 is an explanatory diagram of a method for acquiring a tilt characteristic.

FIG. 7 is an explanatory diagram of a method for acquiring flow velocity characteristics.

FIG. 8 is a diagram illustrating an example of a tilt characteristic.

FIG. 9 is a diagram illustrating an example of flow velocity characteristics.

FIG. 10 is an explanatory diagram of a method of acquiring inclination and flow velocity characteristics depending on the position of a detection device.

FIG. 11 is an explanatory diagram of a gradient of a gradient characteristic line and a gradient of a flow velocity characteristic line.

FIG. 12 is a diagram illustrating an example of a tilt characteristic after optimization.

FIG. 13 is a diagram illustrating an example of flow velocity characteristics after optimization.

FIG. 14 is another configuration diagram (1) of the sensor head according to the present invention.

FIG. 15 is another configuration diagram (2) of the sensor head according to the present invention.

FIG. 16 is another configuration diagram (3) of the sensor head according to the present invention.

FIG. 17 is another configuration diagram (4) of the sensor head according to the present invention.

FIG. 18 is another configuration diagram (5) of the sensor head according to the present invention.

FIG. 19 is another configuration diagram (6) of the sensor head according to the present invention.

FIG. 20 is an explanatory diagram of a confirmation test method (part 1) of wavy correction.

21 is a diagram illustrating an example of a confirmation test result of the wavy correction in FIG. 20.

FIG. 22 is an explanatory diagram of a confirmation test method (part 2) for correction of ripples.

FIG. 23 is a diagram showing an example of a confirmation test result of wavy correction in FIG. 22.

FIG. 24 is an explanatory diagram of continuous casting.

FIG. 25 is an explanatory view of a conventional high-temperature liquid metal flow velocity measuring device using a contact method.

FIG. 26 is an explanatory diagram regarding a velocity effect of a magnetic field and an influence of an eddy current.

FIG. 27 is an explanatory view of a conventional non-contact flow velocity measuring device for high-temperature liquid metal using magnetism (part 1).

FIG. 28 is an explanatory view of a conventional non-contact flow velocity measuring device for high-temperature liquid metal using magnetism (part 2).

FIG. 29 is an explanatory view of a conventional noncontact flow velocity measuring device for high temperature liquid metal using magnetism (part 3).

FIG. 30 is a diagram illustrating the measurement principle of a conventional non-contact flow velocity measuring device for high-temperature liquid metal using magnetism.

FIG. 31 is an explanatory view of a lift-off detection method in a conventional non-contact flow velocity measuring device for high-temperature liquid metal using magnetism.

FIG. 32 is a configuration diagram of a sensor head of a conventional non-contact flow velocity measuring device for high-temperature liquid metal using magnetism.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Sensor head 2 Ceramic round pipe 3 Ceramic round bar S ₁ , S ₂ Flow rate detection detection winding S ₃ , S ₄ Slope detection detection winding S ₅ , S ₆ Lift-off detection detection winding 10 Excitation circuit 11 Oscillator 12 Constant current amplifier 20 Detection circuit 21, 41, 51 Bridge circuit 22, 42, 52 Band pass filter 23, 43, 53 Lock-in amplifier 30 Flow velocity measurement circuit 40 Inclination detection circuit 50 Lift-off measurement circuit 70 Correction circuit 71 A / D Converter 72 Computer 73 D / A converter

Claims (14)

[Claims] 1. A magnetic field perpendicular to the surface of a moving conductive measuring object is excited, and a magnetic field in a direction parallel to the surface of the measuring object and a moving direction thereof is detected in one or more ranges. In the flow velocity measuring method for calculating the flow velocity of the object to be measured based on the magnetic field signals detected in the one or more ranges, the measurement may be performed in one or more ranges that do not match the detection range of the magnetic field for measuring the flow velocity. A magnetic field in a direction parallel to the moving direction of the object is detected, information on the inclination of the surface of the object is determined based on the detected magnetic field signal, and the calculated flow rate of the object based on the information is obtained. A flow velocity measuring method, wherein the flow rate is corrected. 2. An axis which is perpendicular to a surface to be measured in which the exciting magnetic field is axisymmetric in a plane parallel to the moving direction of the object to be measured and perpendicular to the surface of the object to be measured, The magnetic field detection range for calculating is a range of a predetermined length in a direction parallel to the moving direction of the measurement object around the point on the vertical axis, and the detection of the magnetic field for correcting the flow velocity The range is defined as a first in which the exciting magnetic field is axisymmetric with respect to the vertical axis in the plane.
And the center of each of the second points, each having a range of equal length in a direction parallel to the moving direction of the measurement object, and the distance from the vertical axis to each of the first and second points is 2. The flow velocity measuring method according to claim 1, wherein the distance from the vertical axis to the center position of each of the bisected magnetic field detection ranges for calculating the flow velocity is larger than the distance. 3. An axis perpendicular to a surface to be measured in which the exciting magnetic field is line-symmetrical is selected in a plane parallel to a moving direction of the object to be measured and perpendicular to a surface of the object to be measured. Is set to the first detection range in which the excitation magnetic field is line-symmetric with respect to the vertical axis in the plane.
And the center of each of the second points, as a range of the same length in a direction parallel to the moving direction of the measurement object, the detection range of the magnetic field for correcting the flow velocity, the distance from the vertical axis Are centered on third and fourth points, respectively, in which the exciting magnetic field is line-symmetric with respect to the vertical axis in the plane, which are farther from the first and second points, respectively, and 2. The flow velocity measuring method according to claim 1, wherein the lengths are equal to each other in a direction parallel to the moving direction. 4. An axis perpendicular to a surface to be measured in which the exciting magnetic field is axisymmetric in a plane parallel to a moving direction of the object to be measured and perpendicular to a surface of the object to be measured, and Is set to the first detection range in which the excitation magnetic field is line-symmetric with respect to the vertical axis in the plane.
And the center of each of the second points, ranges of equal length in a direction parallel to the moving direction of the measurement object, and a detection range of the magnetic field for correcting the flow velocity, a point on the vertical axis The center position of each range which is a range of a predetermined length in a direction parallel to the moving direction of the measurement object around the center, and bisects the magnetic field detection range for correcting the flow velocity from the vertical axis 2. The flow velocity measuring method according to claim 1, wherein a distance from the vertical axis to each of the first and second points is larger than a distance from the vertical axis to the first and second points. 5. An axis perpendicular to a surface to be measured in which the exciting magnetic field is line-symmetrical is selected in a plane parallel to a moving direction of the object to be measured and perpendicular to a surface of the object to be measured. The magnetic field detection range for calculating is a range of a predetermined length in a direction parallel to the moving direction of the measurement object around the point on the vertical axis, and the detection of the magnetic field for correcting the flow velocity The range, centered on the point on the vertical axis, the detection range of the magnetic field for calculating the flow velocity, the length in the direction parallel to the moving direction of the measurement target, a range that is longer. Claim 1.
The flow velocity measurement method described. 6. A magnetic field detection range for calculating the flow velocity and a magnetic field detection range for correcting the flow velocity, all intersecting with an axis perpendicular to the surface to be measured, and The flow velocity measuring method according to any one of claims 1 to 5, wherein the flow velocity measuring method is provided on a straight line parallel to the moving direction. 7. A detection range of a magnetic field for calculating the flow velocity is set near a central axis of the exciting magnetic field, and a detection range of the magnetic field for correcting the flow velocity is a magnetic field change amount with respect to the flow velocity of the measurement object. The flow velocity measuring method according to any one of claims 1 to 6, wherein the range is set to be the smallest. 8. Exciting means arranged to apply a magnetic field perpendicular to the surface of the moving conductive measurement object;
One or more magnetic field detecting means arranged to detect a magnetic field in a direction parallel to a surface of the object to be measured and a moving direction thereof, and the measurement is performed based on a magnetic field signal detected by the one or more magnetic field detecting means. A flow rate measuring device having a measuring means for calculating a flow velocity of the object, wherein the magnetic field detecting means is arranged to detect a magnetic field in a direction parallel to a moving direction of the measuring object at a position different from a detection position of the magnetic field detecting means. One or more sub-magnetic field detection means, and obtains information related to the inclination of the surface of the object to be measured based on the magnetic field signal detected by the one or more sub-magnetic field detection means, and based on the information, the measurement means A flow rate measuring device comprising: a correction unit configured to correct the calculated flow velocity of the measurement target. 9. An axis perpendicular to a surface to be measured, in which the exciting magnetic field is line-symmetric, is selected in a plane parallel to the moving direction of the object to be measured and perpendicular to the surface of the object to be measured. The magnetic field detecting means for calculating is arranged on the vertical axis as one, and detects a magnetic field over a range of a predetermined length in a direction parallel to the moving direction of the measurement target, and the flow velocity The sub-magnetic field detecting means for correction is disposed on each of the first and second points at which the exciting magnetic field is line-symmetric with respect to the vertical axis in the plane, and Detects a magnetic field over a range of equal length in a direction parallel to the direction of movement of the measurement object, and the distance from the vertical axis to each of the first and second points is greater than the distance from the vertical axis to the first and second points. The detection range of the magnetic field for calculating the flow velocity is 2 Min were respectively than the distance to the center position of the range of flow rate measurement apparatus according to claim 8, characterized in that as each increase. 10. An axis perpendicular to a surface to be measured in which the exciting magnetic field is axisymmetric in a plane parallel to the moving direction of the object to be measured and perpendicular to the surface of the object to be measured, and Magnetic field detecting means for calculating the two are arranged on the first and second points, respectively, where the exciting magnetic field is line-symmetric with respect to the vertical axis in the plane, and A secondary magnetic field detecting means for detecting a magnetic field over a range of the same length in a direction parallel to the moving direction, wherein the sub-magnetic field detecting means for correcting the flow velocity has two distances from the vertical axis as the first and the second. The excitation magnetic field is located on each of the third and fourth points that are symmetrical about the axis perpendicular to the vertical axis in the plane, which are farther than the respective points 2 and 2, and each sub-magnetic field detection means is a measuring object. Equal in the direction parallel to the direction of movement of the object Measuring the flow rate apparatus according to claim 8, characterized in that to detect the magnetic field over the range. 11. An axis perpendicular to a surface to be measured in which the exciting magnetic field is axisymmetric in a plane parallel to the moving direction of the object to be measured and perpendicular to the surface of the object to be measured, and Magnetic field detecting means for calculating the two are arranged on the first and second points, respectively, where the exciting magnetic field is line-symmetric with respect to the vertical axis in the plane, and In order to detect a magnetic field over a range of equal length in a direction parallel to the moving direction, a sub-magnetic field detecting means for correcting the flow velocity is disposed on the vertical axis as one, and To detect a magnetic field over a range of a predetermined length in a direction parallel to the direction of movement, and further from the vertical axis to the center position of each range obtained by bisecting the magnetic field detection range for correcting the flow velocity. The distance of the vertical From said axis than the first and the distance to the second points of the flow rate measuring apparatus according to claim 8, characterized in that as each increase. 12. An axis perpendicular to a surface to be measured in which the exciting magnetic field is axisymmetric in a plane parallel to the moving direction of the object to be measured and perpendicular to the surface of the object to be measured, and The magnetic field detecting means for calculating is arranged on the vertical axis as one, and detects a magnetic field over a range of a predetermined length in a direction parallel to the moving direction of the measurement target, and the flow velocity The auxiliary magnetic field detecting means for correction is arranged on the vertical axis as one, and is more than the detection range of the magnetic field detecting means for calculating the flow velocity, in a direction parallel to the moving direction of the measurement object. 9. The flow velocity measuring device according to claim 8, wherein a magnetic field having a long range is detected. 13. All of the magnetic field detecting means and the sub magnetic field detecting means are arranged on a straight line which intersects an axis perpendicular to the surface to be measured and is parallel to a moving direction of the object to be measured. The flow velocity measuring device according to any one of claims 8 to 12, characterized in that: 14. The detection range of the magnetic field detection means is set to be near the center axis of the excitation magnetic field, and the detection range of the sub-magnetic field detection means is set to a range in which the amount of change in the magnetic field with respect to the flow velocity of the object to be measured is minimized. The flow velocity measuring device according to any one of claims 8 to 13, wherein the flow velocity measuring device is configured as described above.