JP2005114625A - Magnetic substance edge position detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic substance edge position detecting device capable of obtaining sufficiently practical sensitivity even in the case of detecting a magnetic substance as an object to be examined which possesses considerable directivity (anisotropic) in electric magnetic characteristics. <P>SOLUTION: The magnetic substance edge position detecting device is used for detecting the position of a magnetic substance 2, comprising a first and a second magnetic line generating means 11, 12 that produce in collaboration annular magnetic lines of force 18 which go via both sides. Induced current generating means 13, 14 which produce induced current with operation of magnetic lines of force are opposed to the first and second magnetic line generating means 11, 12, separated by an insertion gap S of the magnetic substance 2. Based on the measurement value of the induced current, a calculating means 20 which calculates the position of the magnetic substance 2 inserted in the insertion gap S is provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a magnetic body edge position detection device for detecting the position of a magnetic body.

  For example, the main part of an automobile tire is obtained by coating a large number of steel cords arranged in parallel with each other at a predetermined interval with a covering rubber to obtain a sheet material, and further cutting the sheet material into a desired dimension. Is composed as a material.

  The cutting of the sheet material in the manufacture of such a tire is performed using a position separated from the steel cord closest to the end by a predetermined distance (for example, 0.3 mm) as a cutting end.

  In order to accurately perform such a cut, the position of the steel cord closest to the end while hidden inside the covering rubber (not the edge position of the covering rubber (that is, the edge position of the whole object)) That is, when a plurality of magnetic bodies (steel cords) are regarded as an aggregate, it is necessary to accurately recognize the edge position of the aggregate.

  Thus, for detecting the position of the edge (eg, the edge of the aggregate as described above) of the magnetic material (eg, steel cord as described above) covered with a non-magnetic material (eg, rubber as described above). There are a plurality of types of technologies as described below.

  One of them is a technique based on an optical method that can be applied when the non-magnetic material as a covering is transparent, and a similar technique is when the non-magnetic material is opaque in the visible light region. X-ray observation applied to the above.

  However, the optical method is not suitable when the non-magnetic material as the covering is opaque. That is, for example, since an automobile tire contains carbon black and is opaque in the visible light region, such an optical method cannot be applied.

  Also, in the case of observation with X-rays, it is necessary to limit the entry of people, so the environment that can be adopted is limited, and the imaging cycle is relatively long, so that the detection purpose is the control of the edge position. I can't expect good control.

  In view of such a problem, conventionally, a method for magnetically detecting the edge position has been proposed.

  As a typical example of the technique for magnetically detecting the edge position, there is a variable inductance type method of detecting a change in resistance of a magnetic path when a magnetic material approaches the coil as a change in inductance.

  Examples of such a variable inductance type include a magnetic shielding method and an eddy current method.

  As shown in FIG. 8, the magnetic shielding type detection device has a configuration in which the transmission coil 101 and the reception coil 102 are arranged to face each other with an interval therebetween, and an alternating current (high frequency) is applied to the transmission coil 101. While a magnetic field can be formed around the transmission coil 101 by flowing, an amount of change in the strength (number of magnetic flux) of the magnetic field acting on the reception coil 102 is measured by an ammeter connected to the reception coil 102. Can be detected. Therefore, when the object to be detected (magnetic material) 104 is inserted into the gap between the two coils 101 and 102 with the magnetic field generated by the transmission coil 101 formed, a part of the magnetic flux between the transmission coil 101 and the reception coil 102 is covered. Since the number of lines of magnetic force that are short-circuited by the detection object 104 and intersect the reception coil 102 changes, the measurement value by the ammeter changes, and the insertion amount of the detection object can be obtained based on this change amount.

  On the other hand, as shown in FIG. 10, the eddy current detection device includes a transmission coil 110 and a pair of reception coils 111 and 112. An AC generator 113 is connected to the transmission coil 110, and a high-frequency AC current from the AC generator 113 is supplied. As a result, a magnetic field is generated around the transmission coil 110, and the magnetic field crosses the pair of reception coils 111 and 112.

  The pair of receiving coils 111 and 112 are connected in series with each other, and are connected to the detection circuit via the amplifier 114. In the state where the detection object 104 is not present, the induced currents generated in the receiving coils 111 and 112 are equal to each other, and the detection circuit 115 does not detect the current.

  When the detected object 104 is arranged as shown in FIG. 10, the detected object 104 intersects the magnetic field formed by the transmission coil 110. Then, as shown in FIG. 11, an eddy current 117 is generated on the surface of the detection object 104 in a direction that cancels the magnetic field. Due to the eddy current 117, the magnetic field intersecting the receiving coil 111 and the receiving coil 112 changes. Each of the receiving coils 111 and 112 has a different distance from the object 104 to be detected. For this reason, the induced currents generated in the receiving coil 111 and the receiving coil 112 also have different values. Therefore, in the detection state of the detected object 104, the differential element of the induced current between the reception coil 111 and the reception coil 112 is detected by the detection circuit 115 after being amplified by the amplifier 114.

Thus, the distance of the detected object 104 can be obtained by detecting the differential element of the induced current between the receiving coil 111 and the receiving coil 112 in the detection state (see, for example, Patent Document 1).
Japanese Patent Publication No. 4-3801 (FIG. 4)

  However, any of these variable inductance type detection methods requires the precondition that “the physical property of the magnetic substance in the object to be detected is isotropic with respect to the magnetic flux axis”. The physical properties referred to here are magnetic permeability or induced magnetic resistance in the case of the magnetic shielding method, and conductivity that can suitably form an eddy current in the case of the eddy current method. If such preconditions are not obtained, in the case of the magnetic shielding method, the required sensitivity cannot be obtained depending on the direction of the magnetic axis, and in the case of the eddy current method, an effective size eddy current is not obtained. As a result, it is difficult to obtain practical sensitivity.

  For example, the sheet material as described above has a large direction with respect to its electromagnetic properties because a large number of thin magnetic wires (steel cords) are arranged in parallel at intervals. This state is shown in FIG. That is, as shown in FIG. 12, the sheet material has a relatively small electromagnetic resistance in the Rx direction (longitudinal direction of each steel cord), and in the Ry direction (a direction perpendicular to the Rx direction in the plane of the sheet material). Very large.

  For this reason, when the object 104 to be detected such as the sheet material is set as a detection target, as shown in FIG. 9, the effective short circuit magnetic path is not formed in the apparatus of FIG. Sensitivity cannot be obtained. Further, in the apparatus of FIG. 10, the annular eddy current as shown in FIG. 11 is not suitably formed and does not operate in the original fundamental operation mode. For this reason, sufficient sensitivity cannot be obtained also in this case.

  Furthermore, in any of the above-described variable inductance type detection methods, it is also required that the transmission coil and the reception coil do not undergo impedance changes due to ambient temperature changes or electrical disturbances. However, in the case of the apparatus of FIG. 10, the impedance of the transmission coil actually changes due to the disturbance, and the amount of overcurrent generated on the surface of the object to be detected changes due to the change in the strength of the generated magnetic field. If the impedance of each receiving coil changes, the balance of magnetic coupling between the pair of receiving coils changes, and an accurate difference element cannot be extracted. That is, it is difficult to perform a detection operation stably regardless of the surrounding environment. In the case of the apparatus of FIG. 8 as well, the strength of the magnetic field generated by the transmission coil changes or the induced current by the reception coil changes, so that a stable detection operation that does not depend on the surrounding environment is still possible. Have difficulty.

  In addition, any of the above-described variable inductance type detection methods enables suitable detection only for an object operating on a specific plane, and the insertion amount does not change and only the distance to each coil changes. When there is such a disturbance or when the operation surface of the detection object changes, there is a problem that the same detection value is not obtained even if the insertion amount of the detection object is the same.

  The present invention has been made to solve the above-described problems, and is sufficient even when a magnetic material having a large directionality (anisotropy) in the electromagnetic properties is to be detected. Practical sensitivity can be obtained, preferably suitable for stable detection independent of the surrounding environment such as temperature change or electrical disturbance, or when the operation surface of the object to be detected changes It is an object of the present invention to provide a magnetic edge position detection device that enables easy detection.

  In order to solve the above-mentioned problems, a magnetic body edge position detection device according to the present invention is a first magnetic body edge position detection device for detecting the edge position of a magnetic body. And the second magnetic field line generating means, and the first and second magnetic field line generating means opposed to each other with an insertion interval of the magnetic material, and an induced current generating means for generating an induced current by the action of the magnetic field lines, And an edge position of the magnetic body inserted at the insertion interval is obtained based on the induced current.

  In the magnetic body edge position detecting device of the present invention, it is preferable that the first and second magnetic force line generating means are respectively constituted by coils that generate the magnetic force lines when an alternating current is supplied.

  In this case, it is preferable that the winding direction or the energization direction of the coil is set to be opposite to each other between the first magnetic field line generation unit and the second magnetic field line generation unit.

  In the magnetic body edge position detecting device of the present invention, the first and second induced current generating means are provided on the same side of the first and second magnetic force lines generating means, and the first induced current generation is performed. Preferably, the means is disposed opposite to the first magnetic force line generating means, while the second induced current generating means is disposed opposite to the second magnetic force line generating means.

  In the magnetic body edge position detecting device of the present invention, it is preferable that the induced current generating means comprises a coil.

  In the magnetic body edge position detecting device according to the present invention, the induced current generating means comprises a coil, and the coil winding direction or energization direction between the first induced current generating means and the second induced current generating means. It is also preferable to set the directions opposite to each other.

  In the magnetic body edge position detecting device of the present invention, the magnetic body edge position detecting device further includes reference induced current generating means that is disposed in the vicinity of the first and second magnetic force line generating means and generates a reference induced current by the action of the magnetic force lines, It is preferable to obtain the edge position of the magnetic body as a value corrected using the induced current.

  In this case, it is preferable that the reference induced current generating means is provided in the vicinity of the first magnetic force line generating means and in the vicinity of the second magnetic force line generating means.

  In this case, it is preferable that each reference induced current generating means is composed of a coil, and each reference induced current generating means and the first and second magnetic force line generating means are arranged on the same substrate.

  Moreover, in the magnetic body edge position detection apparatus of this invention, while having two units comprised including the said 1st and 2nd magnetic force line generation means and the said induced current generation means, these two units Is arranged symmetrically with respect to the insertion interval, and the magnetic edge position detecting device further includes a magnetic field generated by the magnetic force generating means of one unit, and the induced current generating means of the one unit is Switching means for switching between a first state in which an induced current is generated and a second state in which the induced current generating means of the other unit generates an induced current by the action of magnetic lines of force generated by the magnetic field generating means of the other unit; It is preferable to obtain the edge position of the magnetic body inserted at the insertion interval by using both the induced current in the first state and the induced current in the second state. Arbitrariness.

  The magnetic body edge position detecting device of the present invention is the magnetic body edge position detecting device for detecting the position of the magnetic body, wherein the magnetic body with respect to the first and second coils and the first and second coils. The third and fourth coils opposed to each other with an insertion interval therebetween and the first and second coils cooperatively generate an annular magnetic field line passing through both, while the action of the magnetic field line causes the first and second coils to cooperate with each other. While the first and third coils generate an induced current and the third and fourth coils cooperate to generate an annular magnetic field line passing through both, the action of the magnetic field line causes the first and second coils to cooperate with each other. Switching means for switching to a second state in which the two coils generate an induced current, and using both the induced current in the first state and the induced current in the second state, the insertion interval The edge position of the magnetic body inserted in It is characterized in Rukoto.

  In the magnetic body edge position detecting device according to the present invention, it is preferable that the magnetic body edge position detecting device further includes a calculation means for calculating the edge position of the magnetic body inserted at the insertion interval based on the measured value of the induced current.

  In the magnetic body edge position detection device of the present invention, it is preferable that the edge position of the magnetic body inserted at the insertion interval is obtained based on a change in the induced current caused by a magnetic flux short circuit by the magnetic body.

  According to the present invention, since the first and second magnetic field lines generating means that jointly generate the annular magnetic field lines passing through both of them are provided, it is possible to preferably cause a magnetic flux short circuit by the magnetic body inserted at the insertion interval. As a result, sufficiently practical sensitivity can be obtained even when a magnetic material having a large directionality (anisotropy) in electromagnetic properties is used as the detection object.

  In addition, according to the present invention, there is further provided a reference induced current generating means that is disposed in the vicinity of the first and second magnetic force line generating means and generates a reference induced current by the action of the magnetic force lines, and the correction is performed using the reference induced current. Since the edge position of the magnetic material is obtained as a value, stable detection independent of the surrounding environment such as a temperature change or an electrical disturbance is possible.

  Further, according to the present invention, two units each including the first and second magnetic force line generating means and the induced current generating means are provided, and the arrangement of these two units is based on the insertion interval. Further, switching means for switching between the first state and the second state is provided, and the induced current in the first state and the induced current in the second state are used together to be inserted into the insertion interval. Since the edge position of the magnetic body is calculated, there is a disturbance that changes the distance between the detected object and the induced current generating means at the insertion interval (when the detected object is vibrated, Suitable detection is possible even when a relative position fluctuation (for example, vertical position fluctuation) between the magnetic force line generating means and the induced current generating means occurs in the detected object.

  According to the present invention, the first and second coils, the third and fourth coils disposed opposite to the first and second coils with an insertion interval of the magnetic material, A first state in which the first and second coils cooperatively generate an annular magnetic field line passing through both, while the third and fourth coils generate an induced current by the action of the magnetic field line; Switching means for switching between a first state and a second state in which the first and second coils generate an induced current by the action of the magnetic force lines, while the coil generates an annular magnetic force line through both of them, Since the edge position of the magnetic material inserted in the insertion interval is obtained using both the induced current in the state and the induced current in the second state, the directionality of the electromagnetic property is large (anisotropic) Sufficiently practical feeling even when using a magnetic material with It is possible to obtain, it is possible to case a distance such that there is a disturbance such as changes to be suitable detection of the induced current generating means and the detection object in the insertion interval.

  In the present invention, for example, the magnetic substance as the object to be detected has a substantially two-dimensional shape (a flat plate shape or a sheet shape) like a steel plate, and particularly extremely long in one direction, and is often rewound. The present invention can be suitably applied to the detection of the ear end position in the case where it is a target of the ear end control in the winding process.

  The present invention also provides a case in which a plurality of wires made of a magnetic material are arranged in a direction orthogonal to the flow direction (insertion direction) in a plane parallel to the flow direction (the insertion direction). It can also be suitably applied to the detection of the position of the edge of the ear).

  Furthermore, the present invention provides a sheet-like shape obtained by coating a magnetic substance wire (corresponding to a steel cord) with some combination (corresponding to a covering rubber) so as to have a predetermined interval, such as a main part of an automobile tire. The present invention can also be suitably applied to the detection of the edge position of the magnetic body in the object. Here, the edge position of the magnetic material in such a sheet-like object means not the edge of the sheet-like object as a whole, but the edge position in the aggregate of a plurality of magnetic wires hidden inside the sheet-like object. To do.

  Hereinafter, a magnetic body edge position detection device according to an embodiment of the present invention will be described with reference to the drawings.

  The magnetic body edge position detection apparatus according to the present embodiment is an apparatus for detecting the position (for example, the edge position) of a magnetic body. Here, the magnetic body is, for example, a magnetic body 2 included in the detected object 1 as shown in FIG. 1 (hidden in the detected object 1). The detected object 1 is, for example, a sheet-like material formed by covering the wires 21 made of a magnetic material in parallel with each other at a predetermined interval and covering with a covering of the magnetic material such as rubber. is there. Further, the magnetic body 2 means an aggregate of the wires 21, and therefore the edge position of the magnetic body 2 is the edge position in the aggregate of the wires 21.

  As shown in FIG. 4, the magnetic body edge position detection device according to the present embodiment includes a detection unit 40 that performs a detection operation, and a calculation that calculates the edge position of the magnetic body 2 based on the detection result of the detection unit 40. Part 20.

  Among these, the detection part 40 is provided with the 1st thru | or 4th coil 11, 12, 13, 14 as shown in FIG.

  Of these, first and second coils (first and second magnetic field lines generating means in the first state, induced current generating means in the second state, first and second induced current generating means) 11, For example, 12 are arranged so as to be located in substantially the same plane. The winding directions of the first and second coils 11 and 12 are the same as each other, and the first and second coils 11 and 12 are connected in series with each other.

  On the other hand, third and fourth coils (inductive current generating means in the case of the first state, first and second induced current generating means, first and second lines of magnetic force in the second state) 13, 14, for example, are arranged in substantially the same plane as each other, and the third and fourth coils 13 and 14 are separated from each other by an insertion interval S (FIG. 2) of the sheet material 1. The coils 11 and 12 are opposed to each other. The winding directions of the third coil 13 and the fourth coil 14 are the same. Further, the third and fourth coils 13 and 14 are connected to each other in series. The third coil 13 is disposed so as to face the first coil 11, and the fourth coil 14 is disposed so as to face the second coil 12.

  The detection unit 40 includes an AC generator 15 connected to the first and second coils 11 and 12. The AC generator 15 receives a current command from a current command value generator 22 (described later) of the computing unit 20 and supplies an AC current to the first and second coils 11 and 12. The two coils 11 and 12 are driven by current. Here, the first and second coils are arranged so that the directions of the alternating current supplied from the AC generator 15 (energization direction) are opposite to each other in the first coil 11 and the second coil 12. 11 and 12 and the AC generator 15 are connected.

  When an alternating current is supplied (energized) from the alternating current generator 15 to the first and second coils 11 and 12, magnetic fields are generated by the first and second coils 11 and 12, respectively, as shown in FIG. . In particular, between the first and second coils 11 and 12, an annular magnetic field line 18 that passes through both the first and second coils is generated by the cooperation of the first and second coils. .

  On the other hand, the third and fourth coils 13 and 14 are positioned so as to intersect the magnetic lines 18 as shown in FIG. 2, and an induced current is generated by the action of the magnetic lines 18. An ammeter 16 is connected to the third and fourth coils 13 and 14. For example, the ammeter 16 measures the sum of the induced currents generated by the third and fourth coils 13 and 14.

  In the case of the present embodiment, the AC generator 15 is connected to the third and fourth coils 13 and 14 in the same manner as is connected to the first and second coils 11 and 12 ( For the sake of simplicity, FIG. 1 shows a state where the AC generator 15 is connected only to the first and second coils 11 and 12). The ammeter 16 is also connected to the first and second coils 11 and 12 in the same manner as it is connected to the third and fourth coils 13 and 14.

  When an alternating current is supplied from the AC generator 15 to the third and fourth coils 13 and 14, a magnetic field is generated by the third and fourth coils 13 and 14. , 14, magnetic field lines (not shown) symmetrical to the magnetic field lines 18 are generated. When magnetic field lines are generated by the third and fourth coils 13 and 14 in this way, the first and second coils 11 and 12 generate induced currents due to the action of the magnetic field lines, and the ammeter 16 calculates the sum of the induced currents. measure.

  Here, the first and second coils 11 and 12 cooperate to generate an annular magnetic field line 18 that passes through both, while the third and fourth coils 13 and 14 are induced by the action of the magnetic field line 18. Is the first state, and the third and fourth coils 13 and 14 cooperate to generate an annular magnetic field line (not shown) that passes through both of them, while the first and second lines act by the action of the magnetic field line. If the state for measuring the induced current generated by the coils 11 and 12 is the second state, the magnetic edge position detecting device according to the present embodiment switches between the first state and the second state in this way. Further, switching means described later is provided.

  Furthermore, the detection unit 40 is arranged in the vicinity of each of the first to fourth coils 11, 12, 13, and 14, and a reference induced current generating coil (reference induced current generating means) that generates a reference induced current by the action of magnetic lines of force. It has. That is, the magnetic body edge position detecting device includes a first reference induced current generating coil 19a in the vicinity of the first coil 11, a second reference induced current generating coil 19b in the vicinity of the second coil 12, and a third coil. 13, a third reference induced current generating coil 19 c in the vicinity of 13 and a fourth reference induced current generating coil 19 d in the vicinity of the fourth coil 14 are provided. Of these, the first and second reference induced current generating coils 19a and 19b are connected in series, and similarly, the third and fourth reference induced current generating coils 19c and 19d are connected in series. The ammeter 16 includes a sum of reference induced currents generated by the first and second reference induced current generating coils 19a and 19b, and a reference induced current generated by the third and fourth reference induced current generating coils 19c and 19d. The sum of each can be measured.

  In the above configuration, for example, the first coil 11, the second coil 12, the first reference induced current generating coil 19a, and the second reference induced current generating coil 19b are the same as shown in FIG. 7, for example. Arranged on the substrate 190. Similarly, the third coil 13, the fourth coil 14, the third reference induced current generating coil 19c, and the fourth reference induced current generating coil 19d are also arranged on the same substrate.

  In addition, the AC generator 15 of the detection unit 40 converts the actual current flowing through the coils 11 to 14 from the calculation unit 20 so that the current flowing therethrough is not affected even if the impedance of the coils 11 to 14 changes. The constant current control method is used to match the command value. This is because, in general, the impedance of the coil is affected by changes in the ambient temperature, and simply passing an alternating current through each of the coils 11 to 14 also affects the amount of magnetic field generated therefrom. is there.

  Moreover, the detection part 40 is provided with the switching circuit 42 which switches the detection signal (measured value of the induced current by the ammeter 16) of each coil 11-14 at a predetermined timing. In addition, the switching means is comprised by the switching circuit 42 of the detection part 40, and the alternating current generator 15 (part).

  Further, the detection unit 40 includes an AM modulation circuit 41 that AM-modulates the detection signals of the coils 11 to 14 and 19a to 19d switched (selected) by the switching circuit 42 and outputs the result to the calculation unit 20. . The AM modulation circuit 41 reduces the influence of electrical disturbance and accurately transmits the detection signals of the coils 11 to 14 and 19a to 19d to the arithmetic unit 20, so that the frequency is sufficiently higher than the frequency generated by the AC generator 15. AM modulation is performed using a high frequency carrier wave.

  On the other hand, the computing unit 20 shown in FIG. 4 computes the edge position of the magnetic body 2 based on the induced current measured by the ammeter 16, and is used to synchronize each part in the magnetic body edge position detecting device. A system clock generation unit 21 that generates a system clock, a current command value generator 22 that outputs a current command value for driving the coils 11 to 14 to the AC generator 15, and an AM modulation circuit 41 of the detection unit 40 The AM demodulation circuit 23 for demodulating the AM modulation and the output signal, the detection unit calibration attenuator 24 for calibrating the individual difference of the detection unit 40, and the detection signal after AM demodulation are detected synchronously. A synchronous detector 25 that extracts an AC component from a detection signal and extracts a DC component and a measured value of a reference induced current generated by each of the reference induced current generating coils 19a to 19d are used. Reference coil correction unit 26 that performs correction (described later), and when the detected object 1 is not in the insertion region (when the insertion amount is zero) and when it is in the fully inserted state, the respective detection values are reflected in the output characteristics. In addition to performing the setting and processing, the gain adjustment for determining the effective area of each detected value in the DOWN cycle (first state) and the UP cycle (second state) (both described later), and the bias adjustment for determining the bias amount, A gain / bias adjustment unit (normalization unit) 27 for performing the above, a nonvolatile memory unit 29 for storing the gain amount and the bias amount according to the characteristics of the magnetic body 2 of the detected object 1, and a nonvolatile memory unit 29 A gain / bias setting unit 30 including an interface for registering (setting) and reading the gain amount and bias amount in the nonvolatile memory unit 29, a DOWN cycle, and an UP cycle Includes a averaging unit 28 for obtaining the final operation result, a by averaging the calculation result (described later) of Le.

  Among these, the AM demodulating circuit 23 includes a band-pass filter 231 that selectively passes only the frequency component of the carrier wave in the signal modulated and output by the AM modulating circuit 41, a rectifier circuit 232, and a low-pass filter 233. ing.

  Next, the basic principle of the magnetic body edge position detection apparatus according to the present embodiment will be described with reference to FIGS. 1 to 3.

  First, in a state where the alternating current is supplied to the first and second coils 11 and 12 (first state), an annular magnetic field line 18 passing through the first and second coils 11 and 12 is generated (FIG. 2). ). In addition, as shown in FIG. 2, the third and fourth coils 13 and 14 are disposed opposite to the first and second coils 11 and 12, so that the third and fourth coils 13 and 14 are The magnetic field lines 18 can be received efficiently. In this state, an induced current is generated in the third and fourth coils 13 and 14 due to magnetic coupling with the first and second coils 11 and 12.

  Next, as shown in FIG. 2, when the detected object 1 including the magnetic body 2 is inserted into the insertion interval S, the magnetic body 2 causes a short circuit T (magnetic flux short circuit) in a part of the lines of magnetic force 18. Then, the induced current generated in the third and fourth coils 13 and 14 decreases. By evaluating this decrease amount, the edge position of the magnetic body 2 can be obtained as the insertion amount of the magnetic body 2.

  Here, the intensity of the magnetic field generated from the first coil 11 is Φ1, the intensity of the magnetic field generated from the second coil 12 is Φ2, and the magnetic path between the first coil 11 and the third coil 13 The resistance is r1, the magnetic path resistance between the second coil 12 and the fourth coil 14 is r2, the magnetic path resistance (magnetic path resistance caused by short-circuiting of the magnetic flux) generated by inserting the object to be detected is rm, The magnetic path resistance between the coil 13 and the fourth coil 14 is rc, and the measured value (third and fourth) by the device 160 (FIG. 3) indicating the number of magnetic lines of force received by the third and fourth coils 13 and 14. 2 is a value representing the number of lines of magnetic force intersecting the coils 13 and 14, and the state of FIG. 2 can be represented by the equivalent circuit of FIG.

  Further, if im is the number of magnetic field lines that are magnetically short-circuited by the magnetic body 2 of the object 1 to be detected, the relationship of ic + im = (number of magnetic field lines passing through r1 or r2) holds, and therefore ic = (r1 or r2 is The number of magnetic field lines passing through) −im.

  Therefore, when the amount of insertion of the detected object 1 into the insertion interval S changes (in other words, when rm (or im) changes), ic changes due to the influence. Therefore, the amount of insertion can be determined by measuring the amount of change of ic. Can be requested.

  Next, a specific detection operation of the magnetic body edge position detection device according to the present embodiment will be described.

  As shown in the time chart of FIG. 5, the magnetic body edge position detecting device is a timing signal synchronized with the system clock of the arithmetic unit 20, and the first and second coils 11 and 12 are being driven. Processing of detection signals from the two reference induced current generating coils 19a and 19b (step S1), detection signals from the third and fourth coils 13 and 14 during driving of the first and second coils 11 and 12 Processing (step S2), processing of detection signals from the third and fourth reference induced current generating coils 19c and 19d during driving of the third and fourth coils 13 and 14 (step S3), third and fourth The processing of the detection signals from the first and second coils 11 and 12 during the driving of the coils 13 and 14 (step S4) is repeated in this order.

  In the following, for the sake of simplicity, it is guided to the third and fourth coils 13 and 14 disposed on the lower side by the action of the magnetic field lines 18 generated by the first and second coils 11 and 12 disposed on the upper side. A DOWN cycle (first state) includes step S2 for generating a current and step S1 performed for correcting the detection result in step S2. Further, step S4 for generating an induced current by the first and second coils 11 and 12 arranged on the upper side by the action of the magnetic field lines generated by the third and fourth coils 13 and 14 arranged on the lower side; The step S3 performed for correcting the detection result in step S4 is referred to as an UP cycle (second state).

  In Step S1 and Step S2 of the DOWN cycle, the AC generator 15 drives the first and second coils 11 and 12 to generate the magnetic force lines 18 based on the current command value from the current command value generator 22. Among these, in step S1, the switching circuit 42 selectively passes only the detection signals (measured values of the induced current) from the first and second reference induced current generating coils 19a and 19b. In step S2, the switching circuit 42 selectively allows only detection signals (measured values of induced currents) from the third and fourth coils 13 and 14 to pass therethrough.

  Next, in steps S3 and S4 of the UP cycle, the AC generator 15 drives the third and fourth coils 13 and 14 based on the current command value from the current command value generator 22, thereby causing magnetic field lines (not shown). ). Among these, in step S3, the switching circuit 42 selectively passes only the detection signals (measured values of the induced current) from the third and fourth reference induced current generating coils 19c and 19d. In step S4, the switching circuit 42 selectively allows only the detection signals (measured values of induced currents) from the first and second coils 11 and 12 to pass therethrough.

  The detection signals in the steps S1 to S4 are input from the detection unit 40 to the calculation unit 20 through AM modulation in the AM modulation circuit 41, respectively.

  In the arithmetic unit 20, first, the AM demodulation circuit 23 performs AM demodulation on the detection signal input for each of the steps S <b> 1 to S <b> 4. At this time, in the first-stage bandpass filter 231, only the frequency component of the carrier wave in the signal modulated by the AM modulation circuit 41 of the detection unit 40 passes. By this processing, an electrical disturbance having a frequency component other than the carrier wave is removed. Subsequently, AM demodulation is performed by the processing of the rectifier circuit 232 and the low-pass filter 233, and the form of the detection signal before AM modulation is restored.

  The detection signal thus AM demodulated is then calibrated by the detection unit calibration attenuator 24. Here, in the detection unit calibration attenuator 24, individual gains are set for the detection signals in the respective steps S1 to S4, and each of these detection signals is calibrated to a predetermined amplitude. Individual differences of the detection unit 40 are calibrated.

  Subsequently, the alternating current component is removed in the synchronous detection unit 25, and the detection level component in each detection signal (the detection level component in each reference induced current generating coil 19a-19d and the component of the insertion amount of the magnetic body 2 in each coil 11-14). Is detected as a DC component. Here, the steps S1 to S4 are switched (the rise and fall of the command signal shown in FIG. 5) using the current command value to the detection unit 40 synchronized with the system clock generated by the calculation unit 20. Therefore, the detection signals in the steps S1 to S4 are naturally synchronized with the system clock. Therefore, it is easy to synchronously detect these detection signals in order, and it is possible to accurately extract the detection level component in the detection signal as a direct current component.

In the reference coil correction unit 26, in each cycle of DOWN and UP,
Detected value in DOWN cycle = detected value from third and fourth coils 13, 14 / detected value from first and second reference induced current generating coils 19a, 19b (a)
Detected value in UP cycle = detected value from first and second coils 11 and 12 / detected value from third and fourth reference induced current generating coils 19c and 19d (b)
Is calculated.

  Here, the first to fourth reference induced current generating coils 19a to 19d are arranged close to the first to fourth coils 11 to 14, respectively. In the magnetic field generated from each coil 11-14, a part of the magnetic flux directly intersects each reference induced current generating coil 19a-19d, so that the induced current obtained from each reference induced current generating coil 19a-19d is the object to be detected. 1 is almost unaffected by the amount of insertion.

  By the way, although each coil 11-14 and each reference induced current generation coil 19a-19d are influenced by ambient temperature change and an electrical disturbance, it is to each coil 11-14 and each reference induced current generation coil 19a-19d. Works equally well.

  In such a situation, the first and second reference induced current generating coils 19a and 19b or the third and third reference induced current generating coils 19a and 19b and the third and Correction (temperature correction) is performed using detection values from the fourth reference induced current generating coils 19c and 19d. In these calculations, the ratio between the detection values from the first and second coils 11 and 12 and the detection values from the third and fourth reference induced current generating coils 19c and 19d, or the third and second Since the ratio between the detected value from the four coils 13 and 14 and the detected value from the first and second reference induced current generating coils 19a and 19b is obtained, the calculation result is calculated as a relative value. For this reason, in addition to the ambient temperature change, there is an effect of removing an electrical disturbance that equally affects each coil.

  Next, the gain / bias adjustment unit (normalization unit) 27 detects each of the case where the magnetic body 2 of the detected object 1 is not in the insertion interval S (when the insertion amount is zero) and when the magnetic body 2 is in the fully inserted state. The method of reflecting the value on the output characteristics is set and processed, and gain adjustment for determining the effective area of each detection value in the DOWN cycle and UP cycle and bias adjustment for determining the bias amount are performed.

  When the AC magnetic characteristics of the magnetic body 2 of the detected object 1 are different, the detected values in each cycle also show different characteristics. However, the gain amount and the bias amount obtained for each type of detected object 1 are stored in a nonvolatile memory. By registering and reading the data in No. 29, even when the detected object 1 having different AC magnetic characteristics is detected, the insertion amount and the characteristics of the detected value output are not changed.

  Further, the averaging unit 28 averages the calculation results of the UP cycle and the DOWN cycle (the calculation results of (a) and (b) above). By performing this averaging process, there is a disturbance in which the detected object 1 is not changed in the insertion interval S and only the distance to each coil is changed (when vibration is generated in the detected object, Alternatively, even if relative position fluctuation (for example, vertical position fluctuation) between the magnetic force line generating means and the induced current generating means occurs in the detected object, the influence on the detected value is reduced.

  This will be described with reference to FIG.

  In FIG. 6, the horizontal axis represents the distance between the object to be detected and the coil (coils 11 to 14 that generate induced currents in steps S2 and S4, respectively), and the vertical axis represents the detected value. The calculation results of (a) and (b) are represented by curves a and b, respectively, and the calculation result obtained by the averaging is represented by curve c.

  Curves a and b are not straight because the detected object 1 is closer to the coils 11 to 14 that generate the induced current, so the curves a and b do not become straight lines, but when they are averaged, they form a shallow inverted kamaboko (curve c). In the curve c, the center portion is particularly close to a straight line. Therefore, by determining and using an allowable range, even if there is the above disturbance that changes only the distance to each coil without changing the insertion amount, the influence on the detection value Can be reduced.

  Therefore, when there is a disturbance in which the insertion amount does not change and only the distance to each coil changes by obtaining the insertion amount of the magnetic body 2 of the detected object 1 using the value after averaging by the averaging unit 28. Also suitable detection is possible.

  According to the embodiment as described above, the state in which the annular magnetic field lines 18 are generated by the cooperation of the first and second coils 11 and 12 (first state), and the third and fourth coils 13 and 14. In order to detect the position of the magnetic body 2 using the detected value of the state in which the annular magnetic field lines are generated by the cooperation (second state), that is, the state in which the magnetic path short-circuit T is suitably generated by the magnetic body 2 Since the position of the magnetic body 2 is detected using the detected value in the above, sufficiently practical sensitivity can be obtained even in the case of the magnetic body 2 having a large directionality (anisotropy) in the electromagnetic properties. Is possible.

  In addition, reference induction current generating coils 19a to 19d that are arranged in the vicinity of the first to fourth coils 11 to 14 and generate a reference induced current by the action of magnetic lines of force are further provided, and the arithmetic unit 20 measures the reference induced current. Since the position of the magnetic body 2 is calculated as a value corrected using the value, stable detection independent of the surrounding environment such as temperature change and electrical disturbance is possible.

  Further, the detection value in the first state and the detection value in the second state are averaged to calculate the position of the magnetic body 2, so that the insertion amount does not change and only the distance to each coil changes. Detection is also possible when there is a strong disturbance or when the motion surface of the object to be detected at the insertion interval S changes (changes in the vertical direction in FIG. 2).

  In the above embodiment, an example in which there are two induced current generating means (the third and fourth coils 13 and 14 in the first state, and the first and second coils 11 and 12 in the second state) will be described. However, the present invention is not limited to this example, and only one induced current generating means may be used.

  Moreover, although the example which generate | occur | produces a cyclic | annular magnetic field line was shown by setting an energization direction to the reverse direction with the 1st coil 11 and the 2nd coil 12 (and the 3rd coil 13 and the 4th coil 14), Annular lines of magnetic force may be generated by reversing the winding direction.

  In addition, the configuration in which the magnetic force line generating means and the induced current generating means are switched between the first state and the second state has been described. However, by providing two units including the magnetic force line generating means and the induced current generating means, the magnetic force lines are generated. The following configuration may be used in which the functions of the means and the induced current generating means are fixed.

  That is, two units configured to include the first and second magnetic field lines generating means and the induced current generating means are provided, and the arrangement of these two units is based on the insertion interval S of the magnetic material. The magnetic body edge position detecting device further includes a first state in which the induced current generating means of the one unit generates an induced current by the action of the magnetic force lines generated by the magnetic force generating means of one unit, and the other unit. Switching means for switching to the second state in which the induced current generating means of the other unit generates an induced current by the action of the magnetic lines of force generated by the magnetic field generating means, and the computing means is a measured value of the induced current in the first state And the measured value of the induced current in the second state may be used together to calculate the position of the magnetic body inserted in the insertion interval S.

It is a typical perspective view which shows the basic composition of the magnetic body edge position detection apparatus which concerns on embodiment of this invention. It is a typical sectional side view for demonstrating the detection operation in the basic composition shown in FIG. It is an equivalent circuit diagram in the magnetic flux for demonstrating the principle of operation in the basic composition shown in FIG. It is a block diagram which shows the whole structure of the magnetic body edge position detection apparatus which concerns on embodiment of this invention. It is a time chart for demonstrating the switching operation | movement by a switching means. It is a graph for demonstrating the magnetic body position calculation using the measured value in a 1st state and a 2nd state. It is a top view which shows a board | substrate provided with a 1st and 2nd coil (or 3rd and 4th coil) and a reference | standard induced current generation coil. It is a typical sectional side view which shows an example of the conventional magnetic body edge position detection apparatus. It is a typical sectional side view for demonstrating the malfunction of the magnetic body edge position detection apparatus of FIG. It is a schematic diagram which shows another example of the conventional magnetic body edge position detection apparatus. FIG. 10 is a schematic diagram showing that it is difficult to generate an ideal eddy current in the detection by the magnetic body edge position detection device of FIG. 10 when there is a large directivity (anisotropy) in the electromagnetic property of the object to be detected. FIG. It is a typical top view which shows a to-be-detected object.

Explanation of symbols

2 Magnetic body 11 First coil (first magnetic field line generating means in the first state, induced current generating means and first induced current generating means in the second state, first coil)
12 Second coil (second magnetic field generating means in the first state, induced current generating means and second induced current generating means in the second state, second coil)
13 Third coil (inductive current generating means and first induced current generating means in the first state, first magnetic force line generating means in the second state, third coil)
14 Fourth coil (inductive current generating means and second induced current generating means in case of first state, second magnetic force line generating means in case of second state, fourth coil)
18 annular magnetic field lines 19a, 19b, 19c, 19d Reference induced current generating coil (reference induced current generating means)
190 Substrate 20 Calculation unit (calculation means)
15 AC generator (switching means)
42 switching circuit (switching means)

Claims (13)

In the magnetic body edge position detecting device for detecting the edge position of the magnetic body,
First and second magnetic field lines generating means for cooperatively generating annular magnetic field lines passing through both;
Inductive current generating means that is disposed opposite to the first and second magnetic force line generating means with an insertion interval of the magnetic material and generates an induced current by the action of the magnetic force lines,
With
An edge position detection device for a magnetic material, wherein the edge position of the magnetic material inserted at the insertion interval is obtained based on the induced current.   2. The magnetic body edge position detecting device according to claim 1, wherein the first and second magnetic force line generating units are each configured by a coil that generates the magnetic force lines when an alternating current is supplied thereto.   The magnetic body edge position detecting device according to claim 2, wherein the winding direction or the energization direction of the coil is set to be opposite to each other in the first magnetic force line generating means and the second magnetic force line generating means. . On the same side as the first and second magnetic field lines generating means, the first and second induced current generating means are provided,
While the first induced current generating means is disposed opposite to the first magnetic field line generating means,
The magnetic body edge position detecting device according to any one of claims 1 to 3, wherein the second induced current generating means is disposed opposite to the second magnetic force line generating means.   5. The magnetic body edge position detecting device according to claim 1, wherein the induced current generating unit includes a coil. 6. The induced current generating means comprises a coil,
The magnetic body edge position according to claim 4, wherein the winding direction or the energizing direction of the coil is set to be opposite to each other in the first induced current generating means and the second induced current generating means. Detection device. A reference induced current generating means that is disposed in the vicinity of the first and second magnetic force lines generating means and generates a reference induced current by the action of the magnetic lines of force;
The magnetic body edge position detecting device according to any one of claims 1 to 6, wherein an edge position of the magnetic body is obtained as a value corrected using the reference induced current.   The magnetic body edge position detecting device according to claim 7, wherein the reference induced current generating means is provided in the vicinity of the first magnetic force line generating means and in the vicinity of the second magnetic force line generating means.   9. The magnetic body edge according to claim 8, wherein each reference induced current generating means comprises a coil, and each reference induced current generating means and the first and second magnetic force line generating means are arranged on the same substrate. Position detection device. While having two units configured to include the first and second magnetic field lines generating means and the induced current generating means,
The arrangement of these two units is symmetrical with respect to the insertion interval,
The magnetic body edge position detection device further includes:
The first state in which the induced current generating means of the one unit generates an induced current by the action of the magnetic line of force generated by the magnetic field lines of one unit, and the action of the magnetic force line of the other unit by the action of the magnetic force lines generated by the magnetic line of the other unit A switching means for switching to a second state in which the induced current generating means generates an induced current;
11. The edge position of the magnetic body inserted at the insertion interval is obtained using both the induced current in the first state and the induced current in the second state. The magnetic body edge position detection apparatus as described in any one of these. In the magnetic body edge position detecting device for detecting the position of the magnetic body,
First and second coils;
Third and fourth coils disposed opposite to the first and second coils with an insertion interval of the magnetic material therebetween;
A first state in which the first and second coils cooperatively generate an annular magnetic field line passing through both, while the third and fourth coils generate an induced current by the action of the magnetic field line; And a switching means for switching to a second state in which the first and second coils generate an induced current by the action of the magnetic lines of force, while the fourth coil and the fourth coil cooperatively generate an annular magnetic line of force through both.
With
Magnetic body edge position detection characterized in that the edge position of the magnetic body inserted at the insertion interval is obtained using both the induced current in the first state and the induced current in the second state. apparatus.   12. The magnetic body according to claim 1, further comprising a calculation unit configured to calculate an edge position of the magnetic body inserted at the insertion interval based on the measured value of the induced current. Edge position detection device. 13. The edge position of the magnetic body inserted at the insertion interval is obtained based on a change in the induced current caused by a magnetic flux short circuit caused by the magnetic body. 13. Magnetic body edge position detection device.

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