JP5522845B2 - Rotary position detector - Google Patents

Description

  The present invention relates to a rotary position detection apparatus including a coil that is AC-excited and a magnetic body or a conductor that is displaced relative to the coil, and detects a rotational position for one rotation or a predetermined angular range. In particular, the present invention relates to a method of generating an output AC signal indicating amplitude function characteristics of a plurality of phases according to a detection target rotation position using only a primary coil excited by one-phase AC.

  An inductive rotational position detection device that produces two-phase output (sine phase and cosine phase output) with one-phase excitation input is known as a “resolver”, and three-phase output (120 degrees with one-phase excitation input) What produces the three shifted phases) is known as “synchro”. The oldest conventional resolver has a secondary winding (sine pole and cosine pole) orthogonal to each other at a mechanical angle of 90 degrees on the stator side, and a primary winding on the rotor side. Is. This type of resolver is disadvantageous because it requires a brush to make electrical contact with the rotor primary winding. On the other hand, the existence of a brushless resolver that does not require a brush is also known. The brushless resolver is provided with a rotary transformer in place of the brush on the rotor side. However, since such a brushless resolver has a configuration having a rotary transformer on the rotor side, it is difficult to reduce the size of the device, and there is a limit to downsizing, and the device configuration is equivalent to that of the rotary transformer. Since the number of parts increases, the manufacturing cost will increase.

  On the other hand, primary windings and secondary windings are arranged on a plurality of convex poles on the stator side, and the rotor is made of a magnetic material having a predetermined shape (eccentric circular shape, elliptical shape, or shape having protrusions). Based on the fact that the gap between the convex pole and the rotor magnetic body changes according to the rotational position, it generates a magnetoresistive change according to the rotational position and obtains an output signal according to this change. A variable magnetoresistive rotational position detection device has long been known as the trade name “Micro Thin”. Also, rotational position detectors based on the same variable magnetoresistive principle are disclosed in, for example, Japanese Patent Laid-Open Nos. 55-46862, 55-70406, 59-28603, and the like. In this case, the position detection method based on the output signal includes a phase method (a method in which the detected position data corresponds to the electrical phase angle of the output signal) and a voltage method (the detected position data is the voltage level of the output signal). Both of these methods are known. For example, when the phase method is adopted, the primary windings arranged at different mechanical angles, such as two-phase excitation input or three-phase excitation input, are excited with a plurality of phases shifted in phase, and electric is generated according to the rotational position. A one-phase output signal is generated with the target phase angle shifted. When the voltage method is adopted, the relationship between the primary winding and the secondary winding is opposite to that of the phase method, and a multi-phase output is generated by one-phase excitation input as in the “resolver”.

  A rotational position detection device that generates a plurality of phase outputs with one-phase excitation input, such as a “resolver”, is typically configured to generate a two-phase output of a sine phase output and a cosine phase output. Therefore, in the conventional contactless / variable magnetoresistive resolver type rotational position detecting device, the stator has at least a four-pole configuration, and each pole is arranged at an interval of 90 degrees in mechanical angle. If the pole is the sine phase, the second pole 90 degrees away from it is the cosine phase, the third pole 90 degrees further away is the minus sign phase, and the fourth pole 90 degrees further away is the minus cosine. It is considered a phase. In that case, the rotor is made of a magnetic material or a conductor in order to cause a change in magnetoresistance according to the rotation of each stator pole, and its shape is a periodic shape such as an eccentric circular shape, an elliptical shape, or a gear shape. Formed. Each stator pole is provided with a primary coil and a secondary coil. When the gap between each stator pole and the rotor changes corresponding to the rotational position of the rotor, the magnetic resistance of the magnetic circuit passing through the stator pole is reduced. Based on this, the degree of magnetic coupling between the primary coil and the secondary coil in the stator pole changes corresponding to the rotational position, and thus an output signal corresponding to the rotational position is induced in the secondary coil. Thus, the peak amplitude characteristic of the output signal of each stator pole shows a periodic function characteristic.

  The conventional contactless / variable magnetoresistive type resolver type rotational position detection device as described above is a primary-secondary induction type in which a primary coil and a secondary coil are provided, and thus the number of coils increases. Therefore, there is a limit to downsizing the structure, and there is a limit to reducing the cost. Furthermore, since the conventional rotational position detecting device has a configuration in which a plurality of stator poles are arranged at equal intervals throughout the entire rotation, there is a limit to the applicable place and space due to the structural limitations. In addition, in the conventional rotational position detecting device, even when a two-phase output of sine and cosine is obtained, the stator cannot be a simple two-pole configuration, but has to be a four-pole configuration. There was a limit to downsizing the structure.

  Further, in Patent Document 1 below, the first coil group and the second coil group are individually excited by a two-phase AC signal of sin ωt and cos ωt, and each coil group is differentially connected between two coils. Dynamic output signals cos θ sin ωt and sin θ cos ωt are respectively output, and both output signals are added or generated to obtain an AC signal sin (ωt−θ) phase-shifted by θ based on the addition theorem of trigonometric functions. It is shown.

JP-A-5-52588

  The present invention has been made in view of the above points, and an object of the present invention is to provide a rotary position detecting device having a small and simple structure. In addition, there is provided a rotary position detection device that can widen the usable phase angle range, and can detect with high resolution even if the displacement of the detection target is minute, and can easily compensate for temperature characteristics. It is something to try.

A rotary position detection apparatus according to a first aspect of the present invention is a coil unit in which at least two pairs of coils excited by a one-phase alternating current signal that is temporally continuous are arranged, and one coil pair The coils are spaced apart at intervals corresponding to a predetermined rotation angle, and the coils are distributed at equal intervals over the entire rotation range, and the coil portions A magnetic response member disposed so as to be rotationally displaced relative to the relative rotation position of the member and the coil portion according to continuous rotation of a detection target, The impedance of the coil is changed in accordance with the rotational position of the coil, and the voltage generated in the coil is increased or decreased while the relative rotational position changes over the entire rotation range based on the impedance change. Unishi is intended increasing or decreasing variation of the voltage of each coil in one coil pair is to indicate the difference between the dynamic characteristics and the have a shape that results in a change in impedance of one cycle per rotation Continuously alternating current with a predetermined periodic amplitude function as an amplitude coefficient by taking out the output voltage generated in the magnetic response member and each coil and obtaining the difference in output voltage between the paired coils A circuit for generating an output signal for each coil pair, wherein the periodic amplitude function of each AC output signal is different in the periodic characteristics by a predetermined phase.

The magnetic response member typically includes at least one of a magnetic body and a conductor. When the magnetic response member is made of a magnetic material, the greater the degree of proximity of the member to the coil, the more the inductance of the coil increases and the electrical impedance of the coil increases. Voltage) increases. Conversely, as the degree of proximity of the magnetic response member to the coil decreases, the inductance of the coil decreases, the electrical impedance of the coil decreases, and the voltage across the terminals of the coil decreases. Thus, as the relative rotation position of the magnetic response member with respect to the coil changes over the entire rotation region with continuous rotation of the detection target, the voltage between the terminals of the coil increases and decreases, and the magnetic response to the coil changes. Rotational position detection can be performed over the entire rotation range of the relative rotation of the members. In addition, since a temporally continuous AC output signal having a predetermined periodic amplitude function as an amplitude coefficient is generated for each coil pair, position detection data can be obtained with a simple configuration based on the AC output signal.
A rotary position detection device according to another aspect of the present invention includes a coil portion and a magnetic response member, and one of the coil portion and the magnetic response member is relatively relative to the other according to a rotational displacement of a detection target. A rotational type position detecting device that detects rotational displacement of the detection target by obtaining an output signal corresponding to the rotational displacement from the coil portion, wherein the coil portion is a predetermined one phase that is temporally continuous. The first and second coil groups are excited by an alternating current signal, and each coil group is provided in a different arrangement along the direction of relative rotational displacement of the magnetic response member with respect to the coil portion. The first coil group generates a temporally continuous output AC signal indicating the amplitude function characteristic of the sine phase according to the relative rotational position of the magnetic response member with respect to the coil portion. And the second coil group generates a temporally continuous output AC signal indicating an amplitude function characteristic of a cosine phase in accordance with a relative rotational position of the magnetic response member with respect to the coil portion. And the first coil group is composed of two-pole coils exhibiting characteristics of a sine phase and a minus sine phase with respect to a relative rotational position of the magnetic response member, and the second coil group includes The magnetic response member is composed of two-pole coils exhibiting the characteristics of a cosine phase and a minus cosine phase with respect to the relative rotational position of the magnetic response member, and each pole coil in each coil group is excited by the one-phase AC signal. a coil only, each of said coils are arranged to be distributed at equal intervals over the entire revolution range, the magnetic response for each of said coil A temporally continuous output AC voltage signal indicating an amplitude change based on an impedance change according to a relative rotational position of the member is taken out from each one coil, and based on this, from two coils of the first coil group The output of the sine phase and the negative sine phase is differentially synthesized to generate a temporally continuous output AC signal indicating the amplitude function characteristic of the sine phase, and the two coils of the second coil group The outputs of the cosine phase and the minus cosine phase outputted from are differentially synthesized to generate temporally continuous output AC signals indicating the amplitude function characteristics of the cosine phase.

Here, an AC signal flowing through the coil is indicated by sin ωt. As an example, when the amplitude coefficient component generated by the increase / decrease change is indicated by a function A (θ) having the rotation angle θ as a variable, the voltage between the terminals of the coil is A ( θ) can be expressed as sin ωt. In this case, the amplitude coefficient component A (θ) increases / decreases with rotation, but the value takes only a positive value. For example, assuming that the curve of the increase / decrease change of the amplitude coefficient component A (θ) shows a characteristic that approximates a sine curve, and its peak value is P, typically, an equation such as A (θ) = P ₀ + Psinθ is used. Is shown. Here, P ₀ ≧ P. That is, the characteristic is such that the value of Psinθ is offset in the plus direction by a certain offset value P ₀ .

  In another embodiment of the present invention, the arithmetic circuit performs a predetermined first calculation and a second calculation using a voltage generated in one coil and the reference voltage, respectively, thereby providing a first A first AC output signal having an amplitude function as an amplitude coefficient and a second AC output signal having a second amplitude function as an amplitude coefficient are generated. In this case, as will be described in detail later, with respect to rotational displacement in a predetermined limited mechanical rotation angle range, a phase detection scale within a predetermined limited range is used instead of a full 360 degree phase detection scale (for example, 90 ° range) position detection data can be obtained. That is, only one coil is used and the detection scale is within a predetermined limited range, but two AC output signals similar to those of the resolver, that is, a sine phase output signal (sin θ sin ωt) and a cosine phase output signal (cos θ sin ωt). ), Can be obtained.

  As one embodiment, the circuit for generating the reference voltage may include a coil (dummy coil) having a predetermined impedance arranged at a position not affected by the displacement of the magnetic response member. Use of such a dummy coil helps to compensate for the temperature drift characteristic of the detection coil provided in the coil section. Of course, the circuit for generating the reference voltage is not limited to the coil, and a voltage generation circuit having another appropriate configuration such as a resistor may be used.

  As one embodiment, the coil section is provided in a limited predetermined angular range within one rotation, and is suitable for detecting a rotational position in the limited predetermined angular range. Good. Such an arrangement of the biased coil portion is effective when the rotary position detecting device according to the present invention is installed later in an existing machine. For example, in the case where an obstacle already exists in a predetermined angle range on the rotation axis to be detected and it is impossible to install a stator coil over a full rotation, it is located at a position in the angle range where no obstacle exists. This is advantageous because it is possible to install an unevenly arranged coil portion.

  When a good conductor such as copper is used as the magnetic response member, the inductance of the coil decreases due to eddy current loss, and the voltage between the terminals of the coil decreases according to the proximity of the magnetic response member. . In this case, detection can be performed in the same manner as described above. As the magnetic response member, a hybrid type in which a magnetic body and a conductor are combined may be used.

According to the present invention, for example, when one coil pair is a sine phase, the increase / decrease change of the voltage between terminals of each coil in the one coil pair shows a differential characteristic, so that one is (P ₀ + Psinθ) sinωt. Then, the other becomes (P ₀ −Psinθ) sinωt. Taking the difference between the two,
(P ₀ + Psin θ) sin ωt − {(P ₀ −Psin θ) sin ωt}
= 2Psinθsinωt
It becomes. Assuming that the other coil pair is a cosine phase, an increase / decrease change in the voltage between terminals of each coil in the coil pair shows a differential characteristic.
(P ₀ + P cos θ) sin ωt − {(P ₀ −P cos θ) sin ωt}
= 2Pcosθsinωt
It becomes. Although such a differential synthesis principle is common to a conventionally known resolver, the conventional resolver required a primary and a secondary coil, but according to the present invention, only a primary coil is provided. Since the secondary coil is not necessary, the coil configuration is simple, and a rotary position detecting device having a simple structure can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment of a rotary position detection apparatus according to the present invention, and FIG. 4A is a schematic front view showing an example of a physical arrangement relationship between a detection coil on a stator side and a magnetic response member on a rotor side. FIG. 4B is a schematic side sectional view, and FIG. 4C is a block diagram showing an example of a circuit related to a detection coil on the stator side. FIGS. 2A and 2B are explanatory diagrams of detection operation of the embodiment of FIG. 1, in which FIG. 1A shows an ideal curve of impedance change of each detection coil with respect to change of the rotation angle θ, and FIG. The figure which shows the amplitude change characteristic with respect to rotation angle (theta) of the output signal obtained by calculating a voltage with a reference voltage. The another example of the rotary position detection apparatus which concerns on this invention is shown, (A) is front schematic, (B) is the side cross-sectional schematic. The further another Example of the rotary type position detection apparatus which concerns on this invention is shown, (A) is front schematic, (B) is the sectional side view. The front schematic diagram which shows the further another Example of the rotary type position detection apparatus which concerns on this invention. 1 shows an embodiment of a rotary position detection device according to the present invention in which one detection coil is provided. FIG. 4A shows a physical arrangement of a detection coil on the stator side and a magnetic response member on the rotor side. An example of the relationship is shown by a schematic front view, (B) is a schematic side sectional view thereof, and (C) is a block diagram showing an example of a circuit related to a detection coil on the stator side. Explanatory drawing of detection operation of the Example of FIG. 1 shows an embodiment of a rotary position detection device according to the present invention of a type that does not use a reference voltage, and FIG. 4A shows a physical arrangement relationship between a detection coil on the stator side and a magnetic response member on the rotor side. 1B is a schematic front view, FIG. 2B is a schematic side sectional view, and FIG. 3C is a block diagram illustrating an example of a circuit related to a detection coil on the stator side. The perspective view which shows schematically the structure of another Example of the rotary type position detector based on this invention of the type which does not use a reference voltage. The perspective view which shows schematically the structure of the other Example of the high-resolution type rotary position detection apparatus which concerns on this invention. FIG. 6 is a perspective view schematically showing another embodiment of the rotary position detection device according to the present invention in a state where it is attached to a target portion.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows an embodiment in which an amplitude change in a full range from 0 degrees to 360 degrees in electrical angle is obtained in two AC output signals each having an amplitude indicating sine and cosine function characteristics. FIG. 1A is a schematic front view showing an example of a physical arrangement relationship between the detection coils 11 and 12 on the stator unit 10 side and the magnetic response member 21 on the rotor unit 20 side in the rotary position detection apparatus according to this embodiment. (B) is a schematic side sectional view, and (C) is a block diagram showing an example of an electric circuit and an electronic circuit related to the detection coils 11 and 12 on the stator 10 side. A rotor part 20 is configured by attaching a magnetic response member 21 having a predetermined shape, for example, an eccentric disk shape, to the rotation shaft 22 to be detected. As an example, the description will proceed assuming that the magnetic response member 21 is made of a magnetic material such as iron. The stator unit 10 is arranged in such a manner as to face the rotor unit 20 in the thrust direction.

  The stator unit 10 includes two coils 11 and 12 as detection coils. The coils 11 and 12 are spaced apart from each other at a predetermined interval in the circumferential direction on the stator substrate 14, and this interval is, for example, 90 ° with respect to the rotating shaft 22. The coils 11 and 12 are wound around iron cores (magnetic cores) 15 and 16, respectively, and the magnetic flux passing through the coils is directed in the axial direction of the rotary shaft 22. A gap is formed between the end surfaces of the iron cores 15 and 16 of the coils 11 and 12 and the surface of the magnetic response member 21 of the rotor unit 20, and the rotor unit 20 rotates without contact with the stator unit 10. The relative arrangement of the rotor portion 20 and the stator portion 10 is determined via a mechanism (not shown) so that the distance of the gap is kept constant. Because of the predetermined shape of the magnetic response member 21 of the rotor unit 20, for example, the shape of an eccentric disk, the area of the end surfaces of the coil cores 15 and 16 facing the magnetic response member 21 through the air gap changes according to the rotational position. To do. Due to the change in the facing gap area, the amount of magnetic flux passing through the coils 11 and 12 through the iron cores 15 and 16 is changed, so that the self-inductance of the coils 11 and 12 is changed. This inductance change is also a change in impedance of the coils 11 and 12.

  The predetermined shape of the magnetic response member 21 of the rotor unit 20 is appropriately designed so as to obtain an ideal sine function curve. For example, in order to obtain a curve of a sine function with one period per one rotation of the rotating shaft 22, the shape is generally close to an eccentric disk as described above. More precisely, it is known that the shape can be appropriately distorted or similar to a heart shape depending on the design conditions such as the coil and iron core shape. How this shape is designed is not the object of the present invention, and the rotor shape used in this known / unknown variable magnetoresistive rotation detector may be adopted. I refrain from making any further mentions. What is important is not what the predetermined shape of the magnetic response member 21 of the rotor portion 20 is, but in short, the inductance change of each coil 11, 12 according to the change of the rotational position of the rotor portion 20, that is, It is only necessary that the impedance change is designed as appropriately as possible so that the impedance changes in the same way as an ideal sine function curve.

FIG. 2A shows an ideal sine function curve of the impedance change of one coil 11 with respect to the change of the rotation angle θ by A (θ). B (θ) represents an ideal sine function curve of the impedance change of the other coil 12 with respect to the change of the rotation angle θ. As can be seen, the other coil 12 is offset by 90 degrees with respect to the coil 11, so that its curve B (θ) corresponds to a cosine function. Thus, if the middle point of the increase / decrease change of each curve A (θ), B (θ) is P ₀ and the amplitude of shake is P, then
A (θ) = P ₀ + Psinθ
B (θ) = P ₀ + P cos θ
It can be expressed. It should be noted that even if P is regarded as 1 and omitted, there is no inconvenience in the description, so this will be omitted in the following description.

As shown in FIG. 1C, each of the coils 11 and 12 is excited with a constant voltage or a constant current by a predetermined one-phase high-frequency AC signal (assumed as sin ωt) generated from an AC generation source 30. . When the inter-terminal voltages of the coils 11 and 12 are denoted by Vs and Vc, respectively, they can be expressed as follows using the rotation angle θ as a detection target as a variable.
Vs = A (θ) sinωt = (P ₀ + sinθ) sinωt
Vc = B (θ) sinωt = (P ₀ + cosθ) sinωt

The coil (dummy coil) 13 generates a reference voltage Vr, and has a predetermined impedance corresponding to the midpoint P ₀ of the increase / decrease change of the curves A (θ) and B (θ), for example. For example, as shown in FIGS. 1A and 1B, the coil 13 is disposed on the stator substrate 14, but is disposed at a position that is not affected by the displacement of the magnetic response member 21 of the rotor unit 20. Therefore, the temperature drift conditions are the same as those of the detection coils 11 and 12. This helps to compensate for the temperature drift error of the detection coils 11 and 12. The coil (dummy coil) 13 is also AC-excited, and the terminal voltage, that is, the reference voltage Vr can be expressed as follows.
Vr = P ₀ sin ωt

The output voltages Vs, Vc, Vr of the coils 11, 12, 13 are input to the analog arithmetic circuit 31, and are calculated according to the following arithmetic expression, whereby the sine and cosine corresponding to the detection target position θ are output from the analog arithmetic circuit 31. Two AC output signals each having an amplitude indicating a function characteristic (that is, two AC output signals having an amplitude function characteristic that is 90 degrees out of phase with each other) are generated. That is, the reference voltage Vr is subtracted from the output voltages Vs and Vc of the coils 11 and 12 for detection.
Vs−Vr = (P ₀ + sinθ) sinωt−P ₀ sinωt = sinθsinωt
Vc−Vr = (P ₀ + cos θ) sinωt−P ₀ sinωt = cos θsinωt

  As described above, by calculating the inter-terminal voltages Vs and Vc of the detection coils 11 and 12 and the reference voltage Vr, the offset corresponding to the reference voltage Vr is eliminated, and the positive / negative sign is obtained with the middle point of the increase / decrease change as the zero point. Can generate two AC output signals (sin θ sin ωt and cos θ sin ωt) having two periodic amplitude functions (sin θ and cos θ) as amplitude coefficients. FIG. 2B schematically shows this state only for the θ component (the component at time t is not shown). As described above, the sine phase output signal (sin θ sin ωt) and the cosine phase output signal (cos θ sin ωt) similar to those of a conventionally known resolver can be obtained only by providing the two detection coils 11 and 12.

  A phase detection circuit (or amplitude phase conversion means) 32 measures the phase component θ of the amplitude functions sin θ and cos θ in the AC output signals sin θ sin ωt and cos θ sin ωt output from the arithmetic circuit 31 and detected by the phase detection circuit (or amplitude phase conversion means) 32. The rotational position θ can be detected by absolute. The phase detection circuit 32 may be configured using, for example, the technique disclosed in Japanese Patent Application Laid-Open No. 9-126809 related to the applicant's application. For example, the first AC output signal sin θ sin ωt is electrically shifted by 90 degrees to generate the AC signal sin θ cos ωt, and by adding and subtracting the second AC output signal cos θ sin ωt, sin (ωt + θ) and sin (ω ωt−θ), and two AC signals (signals obtained by converting phase component θ into AC phase shifts) that are phase-shifted in the leading and lagging directions according to θ are generated, and the phase θ is measured. Rotational position detection data can be obtained. Alternatively, a known RD converter used for processing the resolver output signal may be used as the phase detection circuit 32. The detection processing of the phase component θ in the phase detection circuit 32 is not limited to digital processing, and may be performed by analog processing using an integration circuit or the like. Further, after digital detection data indicating the rotational position θ is generated by the digital phase detection process, this may be converted to analog to obtain analog detection data indicating the rotational position θ. Of course, the output signals sin θ sin ωt and cos θ sin ωt of the arithmetic circuit 31 may be output as they are without providing the phase detection circuit 32. For example, when a three-phase signal similar to synchro is output from the arithmetic circuit 31, such an application form is also possible. The block 33 on the back side of the substrate 14 of the stator unit 10 shown in FIG. 1B indicates that a necessary circuit may be mounted on this portion. For example, only the arithmetic circuit 31 or all the circuits in FIG. 1C including the AC generation source 30 and the phase detection circuit 32 may be mounted at the block 33. In the case where the AC generation source 30 and the phase detection circuit 32 are constituted by digital circuits, they can be made into LSIs, so that the size can be reduced, and these circuits can be mounted integrally on the back side of the stator substrate 14.

Here, the compensation of the temperature drift characteristic will be described. The impedances of the coils 11, 12, 13 change according to the temperature, and the output voltages Vs, Vc, Vr also change. For example, each voltage increases or decreases in one direction as shown by a broken line with respect to a solid curve in FIG. However, in the AC output signals sin θ sin ωt and cos θ sin ωt having the sine and cosine function characteristics obtained by calculating and synthesizing these, the temperature drift is completely compensated for by the calculation of “Vs−Vr” and “Vc−Vr”. As shown in (B), it is not affected by temperature drift. Therefore, in the embodiment in which the dummy coil 13 is used as the reference voltage Vr generating circuit, the value of the reference voltage Vr also changes (temperature drifts) according to the temperature change of the surrounding environment. The temperature drift characteristics of the detection coils 11 and 12 are automatically compensated, and accurate position detection can be expected. Of course, the generation circuit of the reference voltage Vr is not limited to a coil, and other appropriate circuits such as a combination of a coil and a resistor or only a resistor may be used. For example, although it is a little troublesome, the operation of detecting the maximum and minimum values of the curves A (θ) and B (θ) is performed before the detection operation, and the average value is obtained, and the curve A (θ), A voltage corresponding to the midpoint P _{0 of the} increase / decrease change in the value of B (θ) may be obtained and generated as the reference voltage Vr.

  In the embodiment of FIG. 1, the ends of the iron cores (magnetic cores) 15 and 16 of the coils 11 and 12 are oriented in the thrust direction of the rotating shaft 22. However, the present invention is not limited to this. Of course, they may be arranged so as to be oriented in the radial direction. FIG. 3 shows an example in which the iron cores (magnetic cores) 15 and 16 of the coils 11 and 12 are arranged so as to be oriented in the radial direction of the rotary shaft 22, (A) is a schematic front view, and (B) is a side view. FIG. 3, the same reference numerals as those in FIG. 1 indicate elements having the same functions. Therefore, the above description is used and the same description is not repeated. In FIG. 3, the ends of the iron cores 15 and 16 of the coils 11 and 12 are directed inward in the radial direction of the rotating shaft 22 and face the outer peripheral side surface of the magnetic response member 21 of the rotor unit 20 through a gap. is there. In this case, because of the predetermined shape of the magnetic response member 21 of the rotor portion 20 (for example, an appropriately designed shape such as an eccentric disk shape or a heart shape), the end portions of the coil cores 15 and 16 and the outer peripheral side surface of the magnetic response member 21 The distance of the air gap formed with respect to the radial direction varies depending on the rotational position. Due to this change in the opposing gap distance, the amount of magnetic flux that passes through the coils 11 and 12 through the iron cores 15 and 16 changes, so that the self-inductance of the coils 11 and 12 changes and the impedance of each of the coils 11 and 12 changes. . Therefore, the rotation position can be detected by operating in the same manner as in FIG. In the case of FIG. 3, the axial length of the outer peripheral side surface of the magnetic response member 21 of the rotor portion 20 is made somewhat longer. As a result, even if mechanical rotation of the detection target rotating shaft 22 slightly occurs in the thrust direction, the gap formed between the ends of the coil iron cores 15 and 16 and the outer peripheral side surface of the magnetic response member 21 in the radial direction. The distance does not change and the detection accuracy does not decrease. Therefore, the structure in which the air gap is formed in the radial direction as shown in FIG. 3 is used in the thrust direction when the present invention is applied in an environment or machine in which the rotation shaft 22 to be detected is susceptible to mechanical shaking in the thrust direction. This provides the advantage of enabling rotational position detection that is not affected by mechanical shake. Of course, other embodiments shown in FIG. 4 and subsequent figures can be modified in the same manner as in FIG.

  In both the embodiments of FIGS. 1 and 3, the arrangement of the coils 11 and 12 is only provided in a limited predetermined angular range within one rotation (a range somewhat wider than 90 degrees). Therefore, the size of the stator substrate 14 does not have to be wide enough to correspond to the full rotation of the rotor portion 20 as shown in FIGS. 1 and 3, and as shown in FIG. The size can correspond to the specified range. If it does so, even if the obstruction 40 exists in a location as shown in FIG. 4, this can be avoided and a detection apparatus can be installed. Such an arrangement of the biased coils 11 and 12 in the stator unit 10 is effective when the rotary position detecting device according to the present invention is installed later in an existing machine. That is, the obstacle 40 exists when the obstacle 40 already exists in the predetermined rotation angle range of the rotary shaft 22 and it is impossible to install the stator 10 having a size corresponding to one full rotation. This is advantageous because it can be dealt with by installing the stator portion 10 in which the coils 11 and 12 having an uneven arrangement are arranged for a place in an angular range that is not. Of course, in any of the embodiments, the detection target rotating shaft 22 itself may be capable of continuous rotation of one full rotation or more, or may be rotated only within a limited angular range of less than one rotation ( That is, it may be one that reciprocates.

  In the example of FIGS. 1 to 4, the phase component θ in the amplitude function in the AC output signals sin θ sin ωt and cos θ sin ωt obtained based on the outputs of the coils 11 and 12 has a one-to-one correspondence with the mechanical rotation angle θ of the rotating shaft 22. ing. However, the present invention is not limited to this, and the phase component θ in the amplitude function may correspond to n times or 1 / n times the mechanical rotation angle of the rotating shaft 22. As an example, FIG. 5 shows an example in which n = 2 times. FIG. 5 shows a schematic front view similar to FIG. 1 (A). The arrangement interval between the two coils 11 and 12 is about 45 degrees with respect to the rotating shaft 22, and the shape of the magnetic response member 21 </ b> A of the rotor unit 20 is shown. For example, a shape similar to an ellipse is designed in such a way as to cause the coils 11 and 12 to change the impedance of the sine function in two cycles per mechanical rotation of the rotating shaft 22. As a result, the phase component θ in the amplitude function in the AC output signals sin θ sin ωt and cos θ sin ωt obtained based on the outputs of the coils 11 and 12 with respect to the mechanical rotation angle θ ′ of the rotating shaft 22 has a double value. Become. That is, θ = 2θ ′. Not only FIG. 5 but various modifications are possible.

  FIG. 6 shows an embodiment in which only one detection coil 11 is provided in the stator section 10 and a signal equivalent to two AC output signals sin θ sin ωt and cos θ sin ωt is formed based on the output of the one coil 11 and the reference voltage Vr. FIG. 6A is a schematic front view showing an example of a physical arrangement relationship between the detection coil 11 on the stator unit 10 side and the magnetic response member 21B on the rotor unit 20 side according to this embodiment. ) Is a schematic side sectional view, and FIG. 4C is a block diagram showing an example of an electric circuit and an electronic circuit related to the detection coil 11 on the stator 10 side. In the case of this example, the shape of the magnetic response member 21B of the rotor portion 20 is, for example, a spiral cam shape, and the phase component θ in the amplitude function of the AC output signal is approximately 90 degrees with respect to the mechanical rotation angle range of the rotary shaft 22. Designed to show range changes. Due to the spiral cam shape of the rotor portion 20, it is somewhat unsuitable for detecting the full rotation of the rotating shaft 22, but a predetermined mechanical less than one rotation excluding the step portion of the spiral cam shape of the magnetic response member 21B. It is suitable for detection of the rotation position with respect to the rotation angle range.

In the case of FIG. 6, the inter-terminal voltage Vs ′ of the coil 11 increases (or decreases) substantially linearly in one direction in a predetermined mechanical rotation angle range of less than one rotation of the rotating shaft 22, as shown in FIG. ). Among the changes in the inter-terminal voltage Vs ′ of the coil 11, a minimum value or a value twice the value Vm close thereto is set as the reference voltage Vr ′, which is generated by the dummy coil 13. As shown in FIG. 6C, the output voltages of the coils 11 and 13 are input to the arithmetic circuit 31. The arithmetic circuit 31 shown in FIG. 6C subtracts a voltage (that is, Vm) that is ½ of the reference voltage Vr ′ from the inter-terminal voltage Vs ′ of the coil 11 as shown in FIG. A first AC output signal having an amplitude function characteristic that increases from substantially zero level as shown by Va is formed, and the inter-terminal voltage Vs ′ of the coil 11 is subtracted from the reference voltage Vr ′ (that is, 2 Vm). Thus, the second AC output signal having the amplitude function characteristic of the characteristic decreasing from about Vm as shown by the symbol Vb in FIG. 7 is formed.
Va = Vs ′ − (Vr ′ / 2)
Vb = Vr′−Vs ′

  The amplitude function characteristics of these AC output signals in the range W shown in FIG. 7 can be equivalently associated with one quadrant (90 degree range) of the sine function and cosine function. For example, the first AC output signal Va can be associated with a sine function, and can be equivalently handled as sin θ sin ωt. Further, the second AC output signal Vb can be associated with a cosine function, and can be equivalently handled as cos θ sin ωt. However, the range of the phase component θ with respect to the predetermined mechanical rotation range W of the rotary shaft 22 is a range of 90 degrees. Therefore, the phase angle θ detected by the phase detection circuit 32 in FIG. 6C takes a value in the range of 0 ° to 90 °, and this is the absolute rotational position of the rotary shaft 22 in the predetermined mechanical rotation range W. Will be shown.

  As shown in FIG. 7, assuming that the first and second AC output signals Va and Vb showing substantially linear amplitude variation characteristics are associated with sin θ sin ωt and cos θ sin ωt, the amplitude characteristics sin θ and cos θ There will be some non-linearity for 22 mechanical rotation angles. That is, it does not show true sine and cosine function characteristics. However, the phase detection circuit 22 apparently performs phase detection processing on the AC output signals Va and Vb using signals sin θ sin ωt and cos θ sin ωt having amplitude characteristics of sine and cosine functions, respectively. As a result, the detected phase angle θ does not exhibit linearity with respect to the rotation angle of the detection target rotating shaft 22. However, in detecting the rotational position, the non-linearity between the detection output data (detected phase angle θ) and the actual detection target position is often not a very important problem. That is, it is only necessary that position detection can be performed with a predetermined reproducibility. Further, if necessary, the output data of the phase detection circuit 22 is converted using an appropriate data conversion table so that accurate linearity is provided between the detection output data and the actual detection target position. Can be done easily. Therefore, the AC output signals sin θ sin ωt and cos θ sin ωt having the amplitude characteristics of the sine and cosine functions referred to in the present invention do not have to indicate the true sine and cosine function characteristics, and as shown in FIG. It may be something like a triangular wave shape (having a linear inclination), and in short, it is only necessary to show such a tendency.

FIG. 8 shows an embodiment in which the reference voltage generation circuit is omitted and a pair of coils that change differentially is provided instead. FIG. 8A shows each coil and rotor portion on the stator portion 10 side according to this embodiment. An example of a physical arrangement relationship of the magnetic response member 21 on the 20 side is shown by a schematic front view, FIG. 10B is a schematic side sectional view thereof, and FIG. 10C is an electric diagram related to each coil on the stator unit 10 side. It is a block diagram which shows an example of an electronic circuit. In this embodiment, in the stator portion 10, the coil 11A is wound around the iron core 15A at an angular position on the opposite side of the sine output coil 11 and the opposite side of the cosine output coil 12 on the 180 degree side. The coil 12A is wound around the iron core 16A at the angular position, and the reference voltage generating coil 13 is omitted. The shape of the magnetic response member 21 on the rotor unit 20 side may be the same as in the example of FIG. With this configuration, the impedance of each coil in one coil pair changes differentially, so that the increase / decrease change in the voltage between terminals of each coil exhibits differential characteristics. That is, in the pair of the sine phase coils 11 and 11A, assuming that the impedance change of the coil 11, that is, the output amplitude change, exhibits a function characteristic of “P ₀ + Psin θ” with respect to the rotation angle θ of the rotary shaft 22, The change in impedance, that is, the change in output amplitude shows a function characteristic of “P ₀ −Psin θ” with respect to the rotation angle θ of the rotary shaft 22. Similarly, in the pair of the cosine phase coils 12 and 12A, assuming that the impedance change of the coil 12, that is, the output amplitude change, exhibits a function characteristic of “P ₀ + P cos θ” with respect to the rotation angle θ of the rotary shaft 22, The impedance change, that is, the output amplitude change of 12A shows a function characteristic of “P ₀ −P cos θ” with respect to the rotation angle θ of the rotary shaft 22. Hereinafter, for the sake of convenience, P is assumed to be 1 and omitted as in the above.

As shown in FIG. 8C, each of the coils 11, 11A, 12, and 12A is excited by a predetermined AC signal, and the respective inter-terminal voltages Vs, Vsa, Vc, and Vca are rotated by the rotation angle θ as follows. The size corresponding to each impedance corresponding to is shown.
Vs = (P ₀ + sin θ) sin ωt
Vsa = (P ₀ −sin θ) sin ωt
Vc = (P ₀ + cos θ) sinωt
Vca = (P ₀ −cos θ) sin ωt
In the arithmetic circuit 31, as described below, the difference in voltage between terminals of each coil is extracted for each coil pair, and an AC output signal having a predetermined periodic amplitude function as an amplitude coefficient is generated for each coil pair.
Vs−Vsa = (P ₀ + sin θ) sin ωt− (P ₀ −sin θ) sin ωt
= 2sinθsinωt
Vc−Vca = (P ₀ + cos θ) sin ωt− (P ₀ −cos θ) sin ωt
= 2 cos θ sin ωt

  Therefore, as in the previous embodiment, two AC output signals (similar to a resolver) having two periodic amplitude functions (sin θ and cos θ) corresponding to the rotation angle θ of the detection target rotating shaft 22 as amplitude coefficients ( sin θ sin ωt and cos θ sin ωt) can be generated. Compared with a conventional resolver, in the present invention, only a primary coil needs to be provided, and a secondary coil for induction output is not required. Therefore, the coil configuration is simple and the rotary position detecting device has a simple structure. Can be provided. In addition, in order to take out the voltage difference between the terminals of each coil for each coil pair, the coils 11 and 11A are differentially connected without using the special arithmetic circuit 31, and the coils 12 and 12A are connected to each other. The circuit may be simply configured to obtain output AC signals corresponding to the respective differences “Vs−Vsa” and “Vc−Vca” by dynamic connection.

  FIG. 9 shows an embodiment in which the stator portion 10 has a four-coil configuration, as in FIG. However, in FIG. 9, the iron cores 15, 15 </ b> A, 16, 16 </ b> A of the coils 11, 11 </ b> A, 12, 12 </ b> A face in the radial direction of the rotating shaft 22, i.e., face the cam-shaped cylindrical side surface of the magnetic response member 21. It is a thing. For this, a circuit configuration similar to that shown in FIG. 8C may be applied.

  FIG. 10 shows an embodiment in which the stator portion 10 has a four-coil configuration as in FIGS. 8 and 9, but the magnetic response member 21 that rotates together with the rotary shaft 22 has multiple teeth (four teeth in the figure) or Each of the coils 11, 11A, 12, and 12A has a shape that causes a change in magnetoresistance of multiple (N) cycles per rotation, such as a multi-petal (four petals in the figure). That is, it has a structure arranged within a narrow range of 360 degrees / N). In the illustrated example, four coils 11, 12, 11A, and 12A are arranged at intervals of “90 degrees / 4 = 22.5 degrees” within a mechanical angle range of 360 degrees / N = 360/4 = 90 degrees. ing. As in FIG. 9, the magnetic core 15, 15 A, 16, 16 A of each coil 11, 12, 11 A, 12 A is oriented in the radial direction of the rotating shaft 22 and has a four-period unevenness change per rotation. It faces 21 cam-shaped cylindrical side surfaces. Also for this, a circuit configuration similar to that shown in FIG. However, the obtained sine function sin θ and cosine function cos θ have an accuracy of N = 4 times the actual mechanical angle of the rotating shaft 22. For example, if the actual mechanical angle of the rotating shaft 22 is ψ, sin θ = sin Nψ and cos θ = cos Nψ. The example of FIG. 10 has a structure in which the coils 11, 11A, 12, and 12A of the stator unit 10 are arranged within a narrow range corresponding to 1 / N rotation (that is, 360 degrees / N). Similarly, it is very suitable for applications where the stator mounting space is limited to a narrow range.

  11, as in FIG. 3, the stator portion 10 has a two-coil configuration, and the iron cores 15 and 16 of the coils 11 and 12 face the radial direction of the rotating shaft 22, that is, the cam of the magnetic response member 21. The example which made it oppose the cylindrical surface of a cylinder is shown. For this, a circuit configuration similar to that shown in FIG. 8C may be applied. In this example, there is only a limited space between the gear 41 provided on the rotating shaft 22 and the obstacle 42 extending from the lower side, where the stator portion 10 is disposed. In view of this point, since the stator unit 10 has only two coils 11 and 12 arranged at a mechanical angle interval of 90 degrees, the attachment or detachment of the stator unit 10 is performed similarly to the example of FIG. In this case, the limited installation space can be easily accessed from the direction of the arrow R while avoiding the obstacle 42. As indicated by the dotted line, a core for the dummy coil 13 may be disposed in the middle of the stator portion 10. In that case, in order to prevent the dummy coil 13 from being affected by the magnetic response member 21 of the rotor unit 20, the dummy coil 13 is provided with a fixed inductance for generating a predetermined reference voltage. The core end for the coil 13 is masked with a magnetic response material such as iron or copper.

When a good conductor such as copper is used as the magnetic response member 21, the inductance of the coil decreases due to eddy current loss, and the voltage between the terminals of the coil decreases in accordance with the proximity of the magnetic response member 21. become. In this case, the position detection operation can be performed in the same manner as described above. Further, as the magnetic response member 21, a hybrid type that combines a magnetic body and a conductor may be used.
In the case of the type that detects the rotational position of the movement that swings within a rotation range of less than one rotation, the magnetic response member 21 is fixed and the detection coils 11 and 12 are You may make it move according to the displacement of a detection target.
In each of the above embodiments, the number of output AC signals (number of phases) is two phases of sine and cosine (that is, resolver type), but it is of course not limited to this. For example, there may be three phases (the amplitude function of each phase is, for example, sin θ, sin (θ + 120), sin (θ + 240)).

  In addition, as a method of alternating current excitation of the coil, it is also possible to use a known two-phase excitation method in which at least two coils are separately excited with sin ωt and cos ωt. However, the one-phase excitation as described in the above embodiment is superior in various aspects such as simplification of the configuration and temperature drift compensation characteristics.

  In the present invention, the voltage generated in the coil or the voltage between the terminals of the coil is not necessarily limited to the voltage detection type circuit configuration, and should be interpreted broadly. The range to be adopted is also included in the scope. In short, any circuit configuration that can generate and detect an analog voltage or current corresponding to a change in the impedance of the coil may be used.

  As described above, according to the present invention, it is sufficient to provide only the primary coil, and the secondary coil is not necessary. Therefore, it is possible to provide a rotary position detecting device having a small and simple structure. Also, by calculating the output signal of one coil and the reference voltage, it is possible to obtain an output signal showing the amplitude coefficient characteristic of a true sine function or cosine function in which the amplitude coefficient component swings positively or negatively. It is possible to provide a rotary position detecting device that is simple and has a smaller and simpler structure.

10 Stator 11, 12, 11A, 12A Detection coil 13 Reference voltage generating coil (dummy coil)
14 Stator substrate 15, 16, 15A, 16A Iron core (magnetic core)
20 Rotor 21, 21 A, 21 B Magnetic response member 22 Rotating shaft AC source 30
Analog arithmetic circuit 31
Phase detection circuit 32

Claims (2)

A coil portion in which at least two pairs of coils excited by a one-phase alternating current signal arranged in time are arranged, and each coil in one coil pair is separated by an interval corresponding to a predetermined rotation angle. Each coil is disposed at regular intervals throughout the entire rotation range;
A magnetic response member arranged so as to be rotationally displaced relative to the coil part, wherein the relative rotational position of the member and the coil part changes over the entire rotation according to the continuous rotation of the detection target. Then, the impedance of the coil is changed in accordance with the relative rotational position, and the voltage generated in the coil is increased or decreased while the relative rotational position is changed over the entire rotation range based on the impedance change. one of change in increase and decrease of the voltage of each coil in the coil pair is as hereinbefore to indicate differential characteristics, and said magnetic response member has a shape that results in a change in impedance of one cycle per rotation ,
By taking out the output voltage generated in each coil and calculating the difference in output voltage between the coils that make a pair, each coil outputs a continuous AC output signal having a predetermined periodic amplitude function as an amplitude coefficient. A rotational type position detecting device, which is a circuit generated for each pair, wherein the periodic amplitude function of each AC output signal is different in a periodic characteristic by a predetermined phase. A coil portion and a magnetic response member are provided, and one of the coil portion and the magnetic response member is rotationally displaced relative to the other in accordance with a rotational displacement of a detection target, and an output signal corresponding to this is output to the coil portion. A rotational position detecting device for detecting rotational displacement of the detection object by obtaining more,
The coil unit includes first and second coil groups that are excited by a predetermined one-phase alternating current signal that is temporally continuous, and each coil group has a relative rotational displacement of the magnetic response member with respect to the coil unit. The first coil group is provided with different arrangements along the direction, so that the first coil group exhibits a temporal function characteristic of the amplitude function of the sine phase according to the relative rotational position of the magnetic response member with respect to the coil portion. The second coil group is temporally exhibiting an amplitude function characteristic of a cosine phase in accordance with a relative rotational position of the magnetic response member with respect to the coil portion. Arranged to produce a continuous output AC signal,
The first coil group is composed of two-pole coils that exhibit characteristics of a sine phase and a negative sine phase with respect to the relative rotational position of the magnetic response member, and the second coil group is a relative of the magnetic response member. Consists of a two-pole coil that exhibits cosine and negative cosine phase characteristics with respect to the rotational position
Furthermore, each pole coil in each coil group consists of only one coil excited by the one-phase AC signal, and the coils are arranged at equal intervals throughout the entire rotation range, A time-continuous output AC voltage signal indicating an amplitude change based on an impedance change according to a relative rotational position of the magnetic response member with respect to each coil is taken out from each one coil, and based on this, the first coil is extracted. The output of the sine phase and the minus sine phase output from the two coils of the group is differentially synthesized to generate a temporally continuous output AC signal indicating the amplitude function characteristic of the sine phase, and the second When the amplitude function characteristics of the cosine phase are shown by differential synthesis of the output of the cosine phase and the minus cosine phase output from the two coils of the coil group Rotary position detecting device and generates respective output AC signal and continuously.

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