JP2007322229A - Induction-type position detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable high-accuracy position detection, without using specific magnetic responsive member in an induction-type position detector. <P>SOLUTION: The induction-type straight line position detector comprises the primary coil part 10, arranged alternately with the first and the second primary windings 11 and 12 along the displacement direction which are mutually excited in reverse by prescribed AC signals; and at least one secondary winding 22 moving relative to the primary coil part 10. The secondary winding 22 is provided with a secondary coil part 20, having a size smaller than one pitch of the array of the primary winding 11 and 12 of the primary coil part 10. The amplitude-varying output AC signal, corresponding to detection object, can be obtained by out putting the output AC signal combined induction signals, based on each of the first and the second windings 11 and 12 at the secondary coil part 20. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an inductive position detection apparatus that induces and outputs an output AC signal whose amplitude varies according to the displacement of the position of a detection target.

As an example of a conventionally known inductive linear position detection device, a primary winding that is one-phase AC excited and a winding portion that includes a plurality of secondary windings arranged at different positions with respect to the linear displacement direction of a detection target; And a rod formed by repeatedly providing a magnetic response member having a predetermined magnetic response characteristic at a predetermined pitch, and the relative linear position of the rod with respect to the winding portion can be detected. (For example, refer to Patent Document 1 below). According to the induction-type linear position detection device described in Patent Document 1, the relative position of the rod with respect to the winding portion is provided in the rod by changing in conjunction with the change in the linear position of the mechanical system to be detected. The corresponding position of the magnetic response member with respect to the winding portion changes. Therefore, the magnetic coupling between the primary winding and the secondary winding in the winding portion changes according to the change in the linear position of the mechanical system to be detected, and is amplitude-modulated according to the linear position to be detected. An induction output AC signal could be generated in the secondary winding.
JP-A-10-153402

  The inductive linear position detection device shown in Patent Document 1 can perform position detection with high resolution and high accuracy with a small and simple structure, and can perform accurate position detection with compensation for temperature drift characteristics. It had various excellent features. However, since the rod is formed by repeatedly providing a plurality of magnetic response members at a predetermined pitch, depending on the use of the position detection device, it may be unsuitable for mounting on a mechanical system as a detection target.

  The present invention has been made in view of the above points, and without using a magnetic response member having a predetermined pattern for changing the magnetic coupling between the primary winding and the secondary winding. It is an object of the present invention to provide an inductive position detection apparatus that can perform position detection with a simple structure and high accuracy.

  According to the present invention, a primary coil portion formed by alternately arranging first and second primary windings that are oppositely phase-excited by a predetermined AC signal along a displacement direction of a detection target, and the primary coil Comprising at least one secondary winding that is displaced relative to the portion, wherein the at least one secondary winding is an array of first and second primary windings of the primary coil portion. An inductive type including a secondary coil portion having a size smaller than one pitch, and outputting an output AC signal obtained by synthesizing an induction signal based on each of the first and second primary windings in the secondary coil portion. It is a position detection device.

  In one embodiment of the present invention, the output AC signal output from the secondary coil section is equivalent to one pitch of an array of a pair of first and second primary windings in the primary coil section. This is an output AC signal that periodically changes as one cycle.

  In one embodiment of the present invention, four secondary windings are provided in the secondary coil section, and the first and second primary windings are provided in each of the four secondary windings. The amplitude function of the output AC signal obtained by synthesizing the induction signal based on each of the lines corresponds to the sine function, the cosine function, the minus sine function, and the minus cosine function, respectively, and the output AC signal of the sine function and the minus sine function Are differentially synthesized to output a first output AC signal having an amplitude function of a sine function, and an output AC signal of the cosine function and the minus cosine function is differentially synthesized to produce an amplitude function of the cosine function. A second output AC signal having

  According to the present invention, the first and second primary windings that are oppositely phase-excited in the primary coil portion are alternately arranged along the displacement direction of the detection target, and the secondary coil portion Since the winding has a size smaller than one pitch of the arrangement of the first and second primary windings of the primary coil portion, according to the relative displacement of the secondary coil portion with respect to the primary coil portion, The voltages (induction signals) induced in the secondary coil section based on the first and second primary windings exhibit opposite characteristics (push-pull characteristics). Therefore, in the output AC signal obtained by synthesizing the induction signals based on the first and second primary windings, the relative displacement of the secondary coil portion with respect to the primary coil portion appears as amplitude modulation. That is, an output AC signal corresponding to the mutual position (detection target position) of the primary coil unit and the secondary coil unit can be obtained. According to the inductive position detecting device having the above-described configuration, while using a simple structure that does not use a magnetic response member having a predetermined pattern for changing the magnetic coupling between the primary winding and the secondary winding. In addition, there is an excellent effect that position detection with high accuracy can be performed. Further, by using the output AC signal obtained by synthesizing the induction signals based on the first and second primary windings, accurate position detection can be performed without being influenced by the temperature draft characteristic of the coil. There is an excellent effect of becoming.

  Further, according to one embodiment of the present invention, the output AC signal output from the secondary coil section has one pitch of an array of a pair of first and second primary windings in the primary coil section. Since the output AC signal changes periodically as one cycle, the high resolution is obtained by converting the linear displacement over one pitch of the arrangement of the first and second primary windings into a change in the phase angle range of 360 degrees. This makes it possible to perform highly accurate position detection.

  Further, according to one embodiment of the present invention, four secondary windings are provided in the secondary coil section, and the first and second primary windings are respectively provided in the four secondary windings. The amplitude function of the output AC signal obtained by synthesizing the induction signal based on each winding is made to correspond to the sine function, cosine function, minus sine function, and minus cosine function, respectively, and the output AC of the sine function and the minus sine function. A first output AC signal having a sine function amplitude function is output by differentially synthesizing the signals, and an output AC signal of the cosine function and the minus cosine function is differentially synthesized to obtain the amplitude of the cosine function. By outputting a second output AC signal having a function, two output AC signals (sine output and cosine output) similar to those obtained in a conventional resolver are obtained. ) Can be obtained. Therefore, in the inductive linear position detection device according to the one embodiment, phase detection for detecting the phase values of the sine function and the cosine function corresponding to the amplitude values of the first output AC signal and the second output AC signal. A circuit can be used. As such a phase detection circuit, an RD (resolver-digital) converter that has been conventionally used as a phase detection circuit for a resolver can be used, or a phase detection circuit of another type can be used. Therefore, an error occurs in the electrical phase shift in the output AC signal generated in the secondary coil part due to the impedance change of the primary winding of the primary coil part and the secondary winding of the secondary coil part due to temperature change or the like. Inconvenience can be eliminated. The phase detection circuit may be configured with a digital circuit or an analog circuit.

Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a diagram for explaining the configuration of the inductive linear position detection apparatus according to this embodiment. The inductive linear position detection device includes a primary coil unit 10 and a secondary coil unit 20, and FIG. 1 shows a circuit configuration of the primary coil unit 10 and the secondary coil unit 20. Yes. The secondary coil unit 20 is connected to a mechanical system (not shown) to be detected, and can change linearly and reciprocally in conjunction with a change in the linear position of the mechanical system. On the other hand, arrangement | positioning of the primary coil part 10 is fixed suitably. Thus, the secondary coil unit 20 is linearly displaced relative to the primary coil unit 10 in conjunction with the linear displacement of the mechanical system to be detected. Of course, conversely, the primary coil unit 10 may be displaced in conjunction with the mechanical system to be detected, and the secondary coil unit 20 may be fixed. In short, in this linear position detection device, it is only necessary to detect the relative linear position of the secondary coil unit 20 with respect to the primary coil unit 10. In addition, the direction of the linear displacement to be detected is indicated by a double-headed arrow given a symbol X in FIG.

  The primary coil unit 10 includes a plurality of first primary windings 11 and second primary windings 12 that are excited in opposite phases by a predetermined AC signal, and the plurality of first primary windings. The windings 11 and the second primary windings 12 are alternately arranged at equal intervals of appropriate width along the linear displacement direction of the detection target indicated by the arrow X in FIG. In the example illustrated in FIG. 1, a configuration example in which the primary coil unit 10 includes three first primary windings 11 and three second primary windings 12 is illustrated. Each of the first and second primary windings 11 and 12 is constituted by a conductive wire wound around an iron core 13, and physical and electrical characteristics (number of turns, winding direction) of each primary winding 11 and 12. Etc.) shall be the same. As shown in the figure, the first and second primary windings 11 are not limited to a configuration in which the plurality of first and second primary windings 11 and 12 are wound around the common iron core 13. , 12 may be wound around individual iron cores 13 or a plurality of appropriate first and second primary windings (for example, a set of first and second primary windings) 11. , 12 may be wound around one iron core 13.

  In this embodiment, the first primary winding 11 and the second primary winding 12 are excited in opposite phases by AC signals having opposite phases generated from different AC power sources. To do. For example, the first primary winding 11 is excited by an alternating current signal “sin ωt” having an amplitude characteristic of a sine function (indicated by “S” in the figure), and the second primary winding 12 is Excitation with AC signal “−sinωt” of the amplitude characteristic (indicated by “/ S (S bar)” in FIG. 1) of the negative sine function that is in reverse phase to AC signal “sinωt” that excites primary winding 11 Is done. In this specification, the bar symbol indicating phase inversion in FIG. 1 is substituted by “/” for convenience of description. Thus, in the primary coil unit 10, the first primary winding 11 excited by a sine-phase AC signal and the second primary winding 12 excited by a negative sine-phase AC signal include: They are alternately arranged along the linear displacement direction X of the detection target.

  The secondary coil unit 20 includes one secondary winding 22 wound around the iron core 21, and the secondary winding 22 is an arrangement of the first and second primary windings 11 and 12 of the primary coil unit 10. The size is smaller than 1 pitch. The secondary coil part 20 is arranged close to the primary coil part 10 with an appropriate gap, and the gap between the secondary coil part 10 and the primary coil part 10 is a constant distance along the linear displacement direction X. Properly positioned to keep When the first and second primary windings 11 and 12 of the primary coil unit 10 are excited by the AC signal “sin ωt” and the AC signal “−sin ωt”, respectively, the first and second primary windings 11, An alternating voltage (inductive output alternating signal) is induced in the secondary coil unit 20 by mutual induction according to the change in magnetic flux generated in the magnetic flux 12. As understood from the arrangement relationship between the secondary coil unit 20 shown in FIG. 1 and the first and second primary windings 11 and 12 of the primary coil unit 10, the secondary coil unit 20 includes a primary coil. Since part of the magnetic flux generated in each of the first and second primary windings 11 and 12 of the unit 10 is interlinked, the induction output AC signal generated in the secondary coil unit 20 is the first and second The AC voltage (induction signal) induced based on each of the two primary windings 11 and 12 is synthesized. The magnetic influence of the first and second primary windings 11 and 12 of the primary coil unit 10 on the secondary coil unit 20 is secondary to the first and second primary windings 11 and 12. It differs depending on the proximity amount of the coil part 20, that is, the mutual position of the first and second primary windings 11, 12 and the secondary coil part 20. Therefore, as described in detail below, the induction output AC signal induced in the secondary coil unit 20 is a signal having an amplitude variation according to the relative position of the secondary coil unit 20 with respect to the primary coil unit 10. Become.

  If the secondary coil portion 20 is at a position corresponding to the center of the first primary winding 11 and the second primary winding 12 (position indicated by x0, x2, or x4 in FIG. 1), the first 1 The mutual inductances between the secondary winding 11 and the secondary coil unit 20 and between the second primary winding 12 and the secondary coil unit 20 are equal to each other. The magnitudes of the induction signal induced in the secondary coil unit 20 and the induction signal induced in the secondary coil unit 20 based on the second primary winding 12 are the same. That is, the induction output AC signal generated in the secondary coil unit 20 is equally affected by the magnetic influence from both the first and second primary windings 11 and 12.

  Further, the position where the secondary coil portion 20 is entirely opposed to the first primary winding 11 and has the largest amount of proximity, and the furthest away from the second primary winding 12 (indicated by x1 in FIG. 1). Position), the mutual inductance between the first primary winding 11 and the secondary coil portion 20 is maximized, while the mutual inductance between the second primary winding 12 and the secondary coil portion 20 is maximum. Therefore, the induction signal induced in the secondary coil unit 20 based on the first primary winding 11 has a maximum value, and is induced in the secondary coil unit 20 based on the second primary winding 12. The induced signal is a local minimum. That is, the induction output AC signal generated in the secondary coil unit 20 at the position x1 has the maximum magnetic influence from the first primary winding 11 and the magnetic influence from the second primary winding 12. Is minimized.

  Further, the position where the secondary coil portion 20 is entirely opposed to the second primary winding 12 and has the largest amount of proximity, and the most distant from the first primary winding 11 (indicated by x3 in FIG. 1). Position), the mutual inductance between the second primary winding 12 and the secondary coil portion 20 is maximized, while the mutual inductance between the first primary winding 11 and the secondary coil portion 20 is maximum. Therefore, the induction signal induced in the secondary coil unit 20 based on the second primary winding 12 has a maximum value, and is induced in the secondary coil unit 20 based on the first primary winding 11. The induced signal is a local minimum. That is, the induction output AC signal generated in the secondary coil unit 20 at the position x3 has the maximum magnetic influence from the second primary winding 12, and the magnetic influence from the first primary winding 11. Is minimized.

  The mutual relationship between the first primary winding 11 and the secondary coil unit 20 according to the change in the relative position of the secondary coil unit 20 with respect to the primary coil unit 10 (position change between x0 to x4). The change characteristic of the inductance is shown in a graph as shown in FIG. That is, the inductance change between the first primary winding 11 and the secondary coil unit 20 is the position x1 with respect to the change in the linear position of the secondary coil unit 20 (position change between x0 to x4). The local maximum value at position x3, the local minimum value at position x3, and the intermediate value between the local maximum value and the local minimum value at intermediate positions x0, x2 and x4 between the first primary winding 11 and the second primary winding 12. The amplitude function characteristic is as follows. The mutual inductance change characteristic between the first primary winding 11 and the secondary coil unit 20 can be expressed as a sine function “sin θ” for convenience. The angle variable θ correlates with the relative position of the secondary coil unit 20 with respect to the primary coil unit 10.

  In addition, a change in inductance between the second primary winding 12 and the secondary coil unit 20 with respect to a change in the relative position of the secondary coil unit 20 with respect to the primary coil unit 10 (position change between x0 to x4). The characteristics are shown in a graph as shown in FIG. That is, the mutual inductance change between the second primary winding 12 and the secondary coil unit 20 is a position relative to the change in the linear position of the secondary coil unit 20 (position change between x0 to x4). The maximum value is at x1, the minimum value at position x3, and the intermediate value between the maximum value and the minimum value at intermediate positions x0, x2, and x4 between the first primary winding 11 and the second primary winding 12. This shows the amplitude function characteristic. The inductance change characteristic between the second primary winding 12 and the secondary coil unit 20 is the inductance change characteristic sinθ between the first primary winding 11 and the secondary coil unit 20. On the other hand, it can be expressed as a negative sine function “−sin θ” having a reverse phase.

  That is, the set of the first primary winding 11 and the second primary winding 12 provide an inductance characteristic that changes in a push-pull characteristic with respect to the relative position of the secondary coil part 20 to the primary coil part 10. It can be said that one pair is formed. Note that the inductance change characteristic between the first or second primary windings 11 and 12 and the secondary coil unit 20 does not necessarily have to be an accurate sine function or a minus sine function. What has a tendency close to a substantially negative sine function, in short, may be a periodic function having a reverse phase (push-pull characteristic) with respect to the relative position of the secondary coil unit 20 to the primary coil unit 10. The relative size of the secondary winding 22 may be appropriately set with respect to one pitch of the arrangement of the first and second primary windings 11 and 12 so that an ideal periodic function characteristic can be obtained.

  As described above, since the first primary winding 11 is excited by the AC signal “sinωt” of the sine phase, according to the change in the relative position of the secondary coil unit 20 with respect to the primary coil unit 10, The induction signal A induced in the secondary coil unit 20 based on the magnetic influence from the first primary winding 11 can be expressed as “sin θ * sin ωt”. Further, since the second primary winding 12 is excited by the negative sine-phase AC signal “−sin ωt”, the second primary winding 12 is changed in accordance with the change in the relative position of the secondary coil unit 20 with respect to the primary coil unit 10. The induction signal B that is induced in the secondary coil unit 20 based on the primary winding 12 can be expressed as “−sin θ * −sin ωt”. In this specification, the symbol “*” indicates multiplication.

The induction output AC signal induced in the secondary coil unit 20 in accordance with the change in the relative position of the secondary coil unit 20 to the primary coil unit 10 is based on the magnetic influence from the first primary winding 11. This is a signal obtained by synthesizing the induction signal A induced in the secondary coil unit 20 and the induction signal B induced in the secondary coil unit 20 based on the second primary winding 12. Therefore, the induction output AC signal induced in the secondary coil unit 20 in accordance with the change in the relative position of the secondary coil unit 20 with respect to the primary coil unit 10 can be equivalently expressed by the following equation (1).
A + B = (sin θ * sin ωt) + {(− sin θ) * (− sin ωt)}
= Sinθsinωt + sinθsinωt
= 2sin θ sin ωt (1)
The angle variable θ correlates with the relative position of the secondary coil unit 20 with respect to the primary coil unit 10 as described above. In the following, for simplicity of expression, the coefficient 2 in the equation (1) is omitted.

  The induction output AC signal “sin θ sin ωt” induced in the secondary coil unit 20 is a straight line corresponding to one pitch p of the arrangement of the first and second primary windings 11 and 12 in the primary coil unit 10. An amplitude function characteristic that changes periodically with a displacement amount as one cycle is shown. Thus, according to the induction linear position detection device according to this embodiment, the primary coil portion 10 (first and second coils) of the secondary coil portion 20 is used as the induction output AC signal “sin θ sin ωt” induced in the secondary coil portion 20. A signal having an amplitude variation corresponding to the relative position with respect to the second primary winding 11, 12) can be obtained. Further, the inductive output AC signal “sin θ sin ωt” is an output AC that periodically changes with one pitch p of the arrangement of the first and second primary windings 11 and 12 in the primary coil unit 10 as one cycle. Since it becomes a signal, a high-resolution and high-precision position in which the linear displacement of 1 pitch p of the array of the first and second primary windings 11 and 12 is converted into a change in the phase angle range of 360 degrees. Detection can be performed.

  Since the induction output AC signal “sin θ sin ωt” has an amplitude coefficient of the sine function characteristic, that is, an amplitude level (sin θ), a known position data conversion method applicable to such a signal is applied to the secondary coil. Position data indicating the relative position of the unit 20 with respect to the primary coil unit 10 can be obtained. That is, the inductive output AC signal “sin θ sin ωt” output from the secondary coil unit 20 is received by an external utilization device (for example, a microcomputer), and the position data is converted according to an arbitrary position data conversion method mounted on the utilization device side. Obtainable. FIG. 3 is a block diagram showing a schematic configuration for obtaining position data based on the inductive output AC signal “sin θ sin ωt” by the voltage rectification method as an example of the position data conversion method applicable in the linear position detection device shown in FIG. is there. In FIG. 3, the rectification unit 30 rectifies the induction output AC signal sinθsinωt output from the secondary coil unit 20, thereby removing the AC component from the induction output AC signal sinθsinωt, and generating a DC voltage indicating the amplitude level sinθ. I am trying to output. Thereby, the DC voltage output (sin θ) indicating the amplitude level according to the displacement of the secondary coil unit 20 can be used as position detection data.

  Here, compensation for temperature drift characteristics will be described. In the linear position detection apparatus according to this embodiment, the induction output AC signal induced in the secondary coil unit 20 is induced in the secondary coil unit 20 based on the magnetic influence from the first primary winding 11. Is a signal “sin θ sin ωt” obtained by combining the induction signal A and the induction signal B induced in the secondary coil unit 20 based on the second primary winding 12. As described above, the pair of the first primary winding 11 and the second primary winding 12 form a pair that provides an inductance characteristic that varies in a push-pull characteristic with respect to the relative position of the secondary coil unit 20. For this reason, the induction signal A and the induction signal B undergo a push-pull change. Therefore, in the induction output AC signal “sin θ sin ωt” obtained by combining the induction signal A and the induction signal B, the temperature drift error of the coil is compensated. Therefore, according to the linear position detection apparatus according to this embodiment, accurate position detection can be performed without being affected by changes in coil impedance due to temperature drift.

  FIG. 4 is a view for explaining another embodiment of the linear position detecting apparatus according to the present invention. In the linear position detection apparatus shown in FIG. 1, the secondary coil unit 20 has a configuration including only one secondary winding 22. On the other hand, in the linear position detection apparatus shown in FIG. 4, the secondary coil unit 40 includes four secondary windings 41, 42, 43 and 44 for detection. In addition, the same code | symbol is provided about the component demonstrated with reference to the said FIG. 1, and the description is abbreviate | omitted. The secondary windings 41 to 44 are arranged at a predetermined interval within a range of 1 pitch p of the arrangement of the pair of first and second primary windings 11 and 12 in the primary coil unit 10. The amplitude function of the induction output AC signal generated in the windings 41 to 44 is set so as to exhibit desired characteristics.

  For example, the amplitude function of the induction output AC signal generated in each of the secondary windings 41 to 44 can be set to correspond to a sine function, a minus sine function, a cosine function, and a minus cosine function, respectively. In this case, in FIG. 4, the range of 1 pitch p of the arrangement of the first and second primary windings 11 and 12 is divided into four, and the secondary windings 41 to 41 are arranged at the divided positions shifted by p / 4. 44 is arranged. As a result, the amplitude function of the induction output AC signal generated in each of the secondary windings 41 to 44 includes a sine function (secondary winding 41 with “S” added in the figure) and a cosine function (“C” in the figure added). Secondary winding 42), minus sine function (secondary winding 43 with "/ S" in the figure), and minus cosine function (secondary winding 44 with "/ C" in the figure). Each can be set to correspond. Further, as shown in FIG. 4, in the detection coil section 40, the secondary winding 41 corresponding to the sine function and the secondary winding 43 corresponding to the minus sine function are differentially connected, and the cosine function And a secondary winding 44 corresponding to a minus cosine function are differentially connected.

  In each of the secondary windings 41 to 44, the primary coil according to the relative position (linear position of the detection target) of the secondary coil unit 40 with respect to the primary coil unit 10 as described in FIG. An induction output AC signal is generated by synthesizing the induction signals based on each of the first primary winding 11 and the second primary winding 12 of the unit 10. Since the first primary winding 11 and the second primary winding 12 in the primary coil unit 10 are excited in opposite phases, the relative position of the secondary coil unit 20 with respect to the primary coil unit 10 is determined. One pair is provided for each of the secondary windings 41 to 44 to provide an inductance characteristic that varies with a push-pull characteristic. Therefore, between the primary coil part 10 and each coil | winding 41-44 of the secondary coil part 20 with respect to the change of the relative position with respect to the primary coil part 10 of the secondary coil part 40 (position change between x0-x4). The change characteristics of the respective inductances are shown in graphs as shown in FIGS. 5 (a) to 5 (d). In each of FIGS. 5A to 5D, the upper graph with the symbol S indicates the characteristics of the inductance change between the first primary winding 11 and the secondary windings 41 to 44. The lower graph shown with the symbol / S indicates the characteristic of the inductance change between the second primary winding 12 and each of the secondary windings 41 to 44.

  In FIG. 5A, the first primary winding 11 and the secondary winding with respect to the change in the relative position of the secondary coil part 40 to the primary coil part 10 (position change between x0 to x4). 41, the inductance change between the first primary winding 11 and the second primary winding 12 becomes the maximum value at the position x1 and the minimum value at the position x3. The amplitude function characteristic that is an intermediate value between the maximum value and the minimum value is shown. This impedance change characteristic is expressed as a sine function “sin θ” for convenience. The angle variable θ correlates with the relative position of the secondary coil unit 40 with respect to the primary coil unit 10. Further, the change characteristic of the inductance between the second primary winding 12 and the secondary winding 41 has a minimum value at the position x1, a maximum value at the position x3, and an intermediate value at the positions x0, x2, and x4. The amplitude function characteristic is as follows. This can be expressed as a negative sine function “−sin θ” having a phase opposite to the inductance change characteristic sin θ between the first primary winding 11 and the secondary winding 41.

  Further, in FIG. 5B, the first primary winding 11 and the secondary coil with respect to the change in the relative position of the secondary coil part 40 with respect to the primary coil part 10 (position change between x0 to x4). The inductance change between the windings 42 has an amplitude function characteristic that takes a maximum value at the position x0 and the position x4, a minimum value at the position x2, and an intermediate value at the positions x1 and x3. This impedance change characteristic can be expressed as a cosine function “cos θ” with respect to the sine function sin θ in FIG. Further, the change characteristic of the inductance between the second primary winding 12 and the secondary winding 42 is a maximum value at the position x2, a minimum value at the positions x0 and x4, and an intermediate value at the positions x1 and x3. The amplitude function characteristic is as follows. This can be expressed as a negative cosine function “−cos θ” having a phase opposite to the inductance change characteristic cos θ between the first primary winding 11 and the secondary winding 42.

  Further, in FIG. 5C, the first primary winding 11 and the secondary coil with respect to the change in the relative position of the secondary coil part 40 to the primary coil part 10 (position change between x0 to x4). The inductance change between the windings 43 exhibits an amplitude function characteristic that has a minimum value at the position x1, a maximum value at the position x3, and an intermediate value at the positions x0, x2, and x4. This impedance change characteristic can be expressed as “−sin θ” having a phase opposite to that of the sine function sin θ in FIG. Further, the change characteristic of the inductance between the second primary winding 12 and the secondary winding 43 has a maximum value at the position x1 and a minimum value at the position x3. 2 shows an amplitude function characteristic having an intermediate value at the center positions x0, x2, and x4 of the primary winding 12, and this inductance change characteristic can be expressed as a sine function “sin θ”.

  Further, in FIG. 5D, the first primary winding 11 and the secondary winding with respect to the change in the relative position of the secondary coil part 40 with respect to the primary coil part 10 (position change between x0 to x4). The inductance change between the windings 44 shows an amplitude function characteristic having a maximum value at the position x2, a minimum value at the positions x0 and x4, and an intermediate value at the positions x1 and x3. This impedance change characteristic can be expressed as a minus cosine function “−cos θ” with respect to the sine function sin θ in FIG. Further, the change characteristic of the inductance between the second primary winding 12 and the secondary winding 42 is a minimum value at the position x2, a maximum value at the positions x0 and x4, and an intermediate value at the positions x1 and x3. This impedance function characteristic can be expressed as a cosine function “−cos θ”.

The induction output AC signals induced in the secondary windings 41 to 44 in accordance with the change in the relative position of the secondary coil unit 40 to the primary coil unit 10 are the first primary winding 11 and the second This is a signal obtained by synthesizing an induction signal based on each of the primary windings 12.
Therefore, the induction output AC signal induced in the secondary winding 41 in accordance with the change in the relative position of the secondary coil unit 40 with respect to the primary coil unit 10 is understood from the inductance change characteristics shown in FIG. As you can see,
(Sin θ * sin ωt) + {(− sin θ) * (− sin ωt)}
= 2sinθsinωt
Can be represented equivalently by the function of the sine phase.
Further, the induction output AC signal induced in the secondary winding 42 in accordance with the change in the relative position of the secondary coil unit 40 to the primary coil unit 10 is understood from the inductance change characteristics shown in FIG. As you can see,
(Cos θ * sin ωt) + {(− cos θ) * (− sin ωt)}
= 2 cos θ sin ωt
It can be expressed equivalently by the function of cosine phase.
The induction output AC signal induced in the secondary winding 43 in accordance with the change in the relative position of the secondary coil unit 40 to the primary coil unit 10 is understood from the inductance change characteristics shown in FIG. As you can see,
{(−sin θ) * (sin ωt)} + {(sin θ) * (− sin ωt)}
= -2sinθsinωt
It can be expressed equivalently by the function of the minus sign phase.
The induction output AC signal induced in the secondary winding 44 in accordance with the change in the relative position of the secondary coil unit 40 to the primary coil unit 10 is understood from the inductance change characteristics shown in FIG. As you can see,
{(−cos θ) * (sin ωt)} + {(cos θ) * (− sin ωt)}
= -2 cos θ sin ωt
It can be expressed equivalently by the function of the minus cosine phase.

  As shown in FIG. 4, since the secondary winding 41 corresponding to the sine function and the secondary winding 43 corresponding to the minus sine function are differentially connected, the outputs “2 sin θ sin ωt” and 2 of the secondary winding 41 A first output AC signal “4 sin θ sin ωt” having an amplitude function of a sine function can be obtained by differentially combining the output “−2 sin θ sin ωt” of the next winding 43. Further, since the secondary winding 42 corresponding to the cosine function and the secondary winding 44 corresponding to the minus cosine function are differentially connected, the output “2 cos θ sin ωt” of the secondary winding 42 and the secondary winding 44 are connected. The second output AC signal “4 cos θ sin ωt” having the amplitude function of the sine function can be obtained by differentially combining the output “−2 cos θ sin ωt”. In the following, the coefficient “4” in the first and second output AC signals is omitted for the sake of simplicity.

  Thus, two output AC signals “sin θ sin ωt” each amplitude-modulated by two periodic amplitude functions (sin θ and cos θ) including an angle variable θ that correlates with the relative position of the secondary coil unit 40 with respect to the primary coil unit 10. “Cos θ sin ωt” can be obtained. This is equivalent to a sine phase output signal sin θ sin ωt and a cosine phase output signal cos θ sin ωt of a detector conventionally known as a resolver. The names sine phase and cosine phase, and the sine and cosine representation of the amplitude function of the two output AC signals are for convenience. If one is a cosine and the other is a cosine, then either It may be expressed.

  Since each output AC signal obtained by the secondary coil section 40 has an amplitude coefficient of the sine function characteristic, that is, an amplitude level (sin θ), and an amplitude coefficient of the cosine function characteristic, that is, an amplitude level (cos θ), respectively, On the other hand, the position data which shows the relative position with respect to the primary coil part 10 of the secondary coil part 40 can be obtained by applying the well-known position data conversion system applicable. FIG. 6 shows an example of a position data conversion method applicable to the linear position detection apparatus of FIG. 4, based on the first output AC signal “sin θ sin ωt” and the second output AC signal “cos θ sin ωt” by the phase detection method. It is a block diagram which shows the structural example of the phase detection circuit for obtaining data. Two-phase output AC signals α = sin θ sin ωt and β = cos θ sin ωt output from the secondary coil unit 40 are input to the phase detection circuit unit 50. In the phase detection circuit unit 50, the first output AC signal α = sin θ sin ωt is input to the phase shift circuit (phase shift circuit) 51, and its electrical phase is phase-shifted by a predetermined amount (for example, advanced by 90 degrees), and the phase A shifted AC signal α ′ = sin θ cos ωt is obtained.

  The phase detection circuit unit 50 is provided with an addition circuit 52 and a subtraction circuit 53. In the adder circuit 52, the AC signal α ′ = sin θ cos ωt output from the phase shift circuit 51 and the second output AC signal β = cos θ sin ωt output from the secondary coil unit 40 are added, and β + α is added as the addition output. A first electrical AC signal Y1 expressed by the abbreviated expression '= cos θ sin ωt + sin θ cos ωt = sin (ωt + θ) is obtained. In the subtraction circuit 53, the AC signal α ′ = sin θ cos ωt output from the phase shift circuit 51 and the second output AC signal β = cos θ sin ωt output from the secondary coil unit 40 are subtracted, and β A second electrical AC signal Y2 expressed by the abbreviated formula: −α ′ = cos θ sin ωt−sin θ cos ωt = sin (ωt−θ) is obtained.

  Thus, the same linear position X as the first electrical AC signal Y1 = sin (ωt + θ) having the electrical phase angle (+ θ) shifted in the positive direction corresponding to the linear position to be detected. The second electrical alternating current signal Y2 = sin (ωt−θ) having the electrical phase angle (−θ) shifted in the negative direction corresponding to is obtained by electrical processing in the phase detection circuit 50, respectively. .

  The output signals Y1 and Y2 of the adder circuit 52 and the subtractor circuit 53 are input to the zero-cross detection circuits 54 and 55, respectively. The zero-cross detection circuits 54 and 55 detect the zero-crosses of the signals Y1 and Y2. As a method of detecting the zero cross, for example, a zero cross in which the amplitude values of the signals Y1 and Y2 change from negative to positive, that is, zero phase is detected. Thereby, the zero cross detection pulses (zero phase detection pulses) LATP and LATM detected by the zero cross detection circuits 54 and 55 can be obtained.

  The zero-cross detection pulse LATP output from the zero-cross detection circuit 54 indicates the phase shift amount θ in the first electrical AC signal Y1 = sin (ωt + θ) shifted in the positive direction, that is, the linear position X of the secondary coil unit 40 by 1. This corresponds to the data indicated by the advance time (phase shift) with respect to the zero phase time point of the excitation AC signal sin ωt of the next coil unit 10. The zero-cross detection pulse LATM output from the zero-cross detection circuit 55 is a phase shift amount θ in the second electrical AC signal Y2 = sin (ωt−θ) shifted in the negative direction, that is, a straight line of the secondary coil unit 40. The position X corresponds to data indicating the delay time (phase shift) with respect to the zero phase time point of the excitation AC signal sin ωt of the primary coil unit 10.

  Each of the zero cross detection pulse LATP and the zero cross detection pulse LATM is data indicating a phase shift amount θ corresponding to a relative linear position of the secondary coil unit 40 with respect to the primary coil unit 10 by a phase shift. The zero-cross detection pulses LATP and LATM output from the phase detection circuit 50 are supplied to an external utilization device (for example, a microcomputer), and a time difference Δt between the two zero-cross detection pulses LATP and LATM supplied on the utilization device side is obtained. By measuring, position data representing the relative linear position of the secondary coil unit 40 with respect to the primary coil unit 10 can be obtained.

  In principle, only one of the zero cross detection pulses LATP and LATM output from the phase detection circuit 50 can be used as data representing the position of the straight line to be detected. However, due to temperature drift characteristics, the frequency and amplitude level of each excitation AC signal of the primary coil unit 10 may vary, or the impedance in the primary coil unit 10 or the secondary coil unit 40 and other circuit elements may vary. Then, since the phase shift amount θ in each of the zero cross detection pulses LATP and LATM includes an error component ε based on the temperature drift characteristic, only one of the zero cross detection pulses LATP or LATM is used as position data. With the configuration, the accuracy of position detection becomes insufficient. However, since this error component ε appears in the same value and in the same direction (same value and same sign) in the zero cross detection pulses LATP and LATM, the error component ε is canceled out in the time difference Δt between the zero cross detection pulses LATP and LATM. become. Therefore, by measuring the time difference Δt between the zero-cross detection pulses LATP and LATM as described above and obtaining data in which the error component ε is canceled out, highly accurate position detection that is not affected by temperature drift becomes possible.

  7A is a schematic side view showing an example of a sensor shape to which the linear position detection device shown in FIG. 1 is applied, and FIG. 7B is an example of a sensor shape to which the linear position detection device shown in FIG. 4 is applied. It is a schematic side view which shows. In both figures (a) and (b), the secondary coil sections 20 and 40 are shown in cross section. As shown in (a) and (b), the primary coil unit 10 in which the first and second primary windings 11 and 12 are alternately arranged along the linear displacement direction X includes a secondary coil unit 20. , 40 can be applied to the linear position detecting device according to the present invention.

  As described above, according to the inductive linear position detection device according to this embodiment, the first and second primary windings 11 and 12 that are excited in opposite phases in the primary coil unit 10 are detected straight lines. In the secondary coil section 20, the output AC signal obtained by synthesizing the induction signals based on each of the first and second primary windings 11 and 12 is output in a predetermined manner by being arranged alternately along the displacement direction. Although it has a simple structure that does not include a magnetic response member made of a pattern, it has an excellent effect that position detection with high accuracy can be performed.

  In FIG. 4, the four secondary windings 41 to 44 are within the range of 1 pitch p of the arrangement of the first and second primary windings 11 and 12 of the primary coil portion 10. Although the example of arrangement | positioning was shown, the arrangement | positioning aspect of the four secondary windings 41-44 is not this limitation. FIG. 8 shows a modification of the arrangement of the four secondary windings 41 to 44. That is, the amplitude function of the induction output AC signal generated in the secondary winding 41 is a sine function, the amplitude function of the induction output AC signal generated in the secondary winding 42 is a cosine function, and the induction output AC signal generated in the secondary winding 43 is As long as the amplitude function is a minus sine function and the amplitude function of the inductive output AC signal generated in the secondary winding 44 exhibits a characteristic corresponding to the minus cosine function, as shown in FIG. 44 may be appropriately dispersed with respect to the primary coil unit 10.

  In each of the induction type linear position detecting devices, the first primary winding 11 and the second primary winding 12 of the primary coil unit 10 are in opposite phases generated from different AC power sources. Although it was supposed to be excited by the AC signal, as another circuit configuration of the primary coil unit 10, as shown in FIG. 9, the first primary winding 11 and the second coil are connected to one AC power source. By connecting the primary windings 12 with opposite polarities, the first primary winding 11 and the second primary winding 12 may be excited in opposite phases. In addition, in another circuit configuration example of the primary coil unit 10 shown in FIG. 9, only one each of the first primary winding 11 and the second primary winding 12 are drawn for convenience of illustration and description. Although not shown, in another circuit configuration example of the primary coil unit 10, the first primary winding 11 and the second primary winding 12 are similar to the configuration shown in FIG. 1 or FIG. 4. A plurality of each may be provided.

  In addition, as to how to use the inductive output AC signal induced in the secondary coil section 20 or 40 in each inductive linear position detection device, the voltage rectification method illustrated with reference to FIG. 3 or with reference to FIG. In addition to the phase detection method described above, other conventionally known methods such as a PWM conversion method may be applied.

  Further, in the inductive linear position detection device shown in each of the above embodiments, the secondary coil unit 20 or 40 is relatively linear with respect to the primary coil unit 10 in conjunction with the linear displacement of the mechanical system to be detected. An example of a displacement configuration has been described. However, even if the actual movement of the detection target is a rotational movement or a rotation or swinging movement within a limited angle range, the movement of the secondary coil unit 20 linked to the actual movement of the detection target is 1 In the case where the movement equivalent to the linear displacement relative to the secondary coil unit 10 can be considered, the induction type linear position detection device shown in each of the above embodiments can be used even if the actual movement of the detection target is not linear movement. Can be applied.

The figure which shows the structural example of the induction | guidance | derivation type | mold linear position detection apparatus which concerns on one Example of this invention. In the inductive linear position detection apparatus according to the embodiment, (a) shows an inductance change characteristic based on the first primary winding, (b) shows an inductance change characteristic based on the second primary winding, (C) is an output AC signal obtained by synthesizing induction signals based on the first and second primary windings. The block diagram which shows the structural example of the circuit for position data measurement by the voltage rectification system applicable to the induction | guidance | derivation type | mold linear position detection apparatus which concerns on the Example. The figure which shows the structural example of the induction | guidance | derivation type | mold linear position detection apparatus which concerns on another Example of this invention. (A)-(d) is each inductance based on the 1st and 2nd primary winding in each of the four secondary windings with which the induction type linear position detection apparatus based on another Example shown in FIG. 4 is provided. The change characteristic is shown. The block diagram which shows the structural example of the circuit for position data measurement by the phase detection system applicable to the induction | guidance | derivation type | mold linear position detection apparatus which concerns on another Example shown in FIG. Sensor shape, The figure which shows the example of a change of arrangement | positioning of the secondary winding in the induction | guidance | derivation type | mold linear position detection apparatus which concerns on another Example shown in FIG. The circuit diagram which shows another structural example of the primary coil part in the induction | guidance | derivation type | mold linear position detection apparatus which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Primary coil part, 11 1st primary winding, 12 2nd primary winding, 13 Iron core, 20 Secondary coil part, 21 Iron core 22 Secondary winding, 30 Rectification part, 40 Coil part for detection 41 secondary winding (sine function), 42 secondary winding (cosine function), 43 secondary winding (minus sine function), 44 secondary winding (minus cosine function), 50 phase detection circuit unit, 51 Phase shift circuit, 52 addition circuit, 53 subtraction circuit, 54,55 zero cross detection circuit

Claims (3)

A primary coil unit in which first and second primary windings that are excited in opposite phases by a predetermined AC signal are alternately arranged along a linear displacement direction of a detection target;
It comprises at least one secondary winding that is displaced relative to the primary coil portion, and the at least one secondary winding is an arrangement of the first and second primary windings of the primary coil portion. A secondary coil portion having a size smaller than one pitch of
An inductive position detecting device that outputs an output AC signal obtained by synthesizing an inductive signal based on each of the first and second primary windings in the secondary coil section.   The output signal output from the secondary coil unit is an output AC signal that periodically changes with one pitch of the arrangement of the first and second primary windings in the primary coil unit as one cycle. The inductive position detecting device according to claim 1, wherein   In the secondary coil section, four secondary windings are provided, and in each of the four secondary windings, an output obtained by synthesizing induction signals based on each of the first and second primary windings. The amplitude function of the signal is equivalent to the sine function, cosine function, minus sine function, and minus cosine function, respectively, and the amplitude of the sine function is obtained by differentially synthesizing the output AC signal of the sine function and the minus sine function. Outputting a first output AC signal having a function, and differentially combining the output AC signals of the cosine function and the minus cosine function to output a second output AC signal having an amplitude function of the cosine function. The inductive position detecting device according to claim 1 or 2, wherein

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