Resolver

Abstract

A resolver comprises: a first substrate (21) having a plurality of layers (Lf1, Lb1); and two-phase coils (11, 12). Each of the two-phase coils (11, 12) has, as a region forming one magnetic pole, first portions (11f, 12f) that extend in a first direction (Dc1) with respect to the center of the magnetic pole in a common layer (Lf1), and second portions (11b, 12b) that extend in a second direction (Dc2) with respect to the center of the magnetic pole in another layer (Lb1) other than the common layer, and that are laminated on the first portions (12f, 11f) of a coil (12, 11) having a phase different from that of the coil (11, 12). The first portions (11f, 12f) and the second portions (11b, 12b) each have a substantially closed shape formed by winding a first conductive wire (W11, W12) around the center of the magnetic pole, and are electrically connected to each other via single through-holes (11h, 12h).

Description

resolver

[0001] The present invention relates to a resolver that detects the rotation angle of a rotor relative to a stator.

[0002] Conventionally, resolvers that detect the rotation angle of a rotor relative to a stator have been known that have a structure in which two-phase sheet coils are formed in multiple layers. For example, Patent Document 1 discloses a resolver in which sine wave coils and cosine wave coils (two-phase coils) are formed as detector coils in both a first detector coil layer and a second detector coil layer.

[0003] In Patent Document 1, the sine wave coil and the cosine wave coil are each divided and arranged in a first detector coil layer and a second detector coil layer, respectively, and are arranged in positions corresponding to each other. Specifically, a sine wave split coil constituting a part of the sine wave coil on the first detector coil layer is stacked with a cosine wave split coil constituting the other part of the cosine wave coil on the second detector coil layer. Furthermore, a cosine wave split coil constituting a part of the cosine wave coil on the first detector coil layer is stacked with a sine wave split coil constituting the other part of the sine wave coil on the second detector coil layer.

[0004] Patent Document 1 states that this makes it possible to maintain a constant positional relationship (gap) between each of the sine wave coil and cosine wave coil and the excitation coil facing these coils, thereby reducing errors (gain differences) that occur due to changes in the gap. Also, it states that by arranging the sine wave coil and cosine wave coil so that they output sine wave or cosine wave detection signals when a uniform magnetic flux facing in the same direction acts, it is possible to obtain an appropriate detection signal from the detection coil as a whole.

[0005] JP 2011-137633 A

[0006] In order to suppress the gain difference between the coils of two phases, it is necessary to suppress the difference between the impedance between the excitation coil and the sine wave coil and the impedance between the excitation coil and the cosine wave coil. Therefore, when one part of the coil of each phase is arranged on a different layer, the coil of each phase must have a connection point that penetrates the substrate having these layers and electrically connects the one part to the other part. However, the resistance value of the wiring at the connection point is likely to vary due to manufacturing reasons (e.g., etching and plating processes).

[0007] In the resolver disclosed in Patent Document 1, the sine wave split coils of the first detector coil layer and the second detector coil layer are each U-shaped with their openings facing each other in the circumferential direction, and a conductor wire alternately travels back and forth between the first detector coil layer and the second detector coil layer to form a single sine wave coil. A cosine wave coil is also formed in a similar manner. When multiple connection points are provided for the conductor wire to alternately travel back and forth between the first detector coil layer and the second detector coil layer, differences in wiring resistance due to the above-mentioned resistance variation can occur between the two-phase coils. This can cause the electrical characteristics of the two-phase coils to differ, resulting in a deterioration in the detection accuracy of the resolver. This issue can occur not only when the two-phase coils are used as detector coils, but also when they are used as excitation coils.

[0008] The present invention has been devised in view of the above-mentioned problems, and has as one object to suppress the difference in wiring resistance occurring between the two-phase coils in a resolver in which two-phase coils are arranged on a substrate having multiple layers, thereby improving the detection accuracy of the resolver. However, in addition to this object, another object of the present invention is to achieve effects that are derived from the configurations shown in the below-described embodiments for carrying out the invention, and that cannot be obtained by conventional techniques.

[0009] The disclosed resolver can be realized as the following disclosed aspects (application examples), which solve at least some of the above problems.

[0010] The resolver disclosed herein is a resolver that detects a rotation angle of a rotor relative to a stator, and includes: a sheet-like first substrate provided on one of the stator and the rotor and having multiple layers stacked in a rotational axis direction of the rotor; and sheet-like two-phase coils provided on the first substrate and transmitting AC signals whose electrical phases differ by 90 degrees from each other. Each of the two-phase coils has, as a portion forming one magnetic pole, a first portion extending in a first circumferential direction about a center of the magnetic pole in a common layer of the multiple layers; and a second portion extending in a second direction opposite to the first direction about the center of the magnetic pole in the other layer of the multiple layers other than the common layer, and stacked on the first portion of the coil of a different phase from the first coil. Each of the first portion and the second portion has a substantially closed shape formed by winding a first conductor around the center of the magnetic pole, and is electrically connected to each other via a single through hole.

[0011] According to the disclosed resolver, it is possible to suppress the difference in wiring resistance occurring between the coils of two phases and improve the detection accuracy of the resolver.

[0012] 5 is a schematic diagram showing the structure of a resolver according to an embodiment. FIG. 1 is a plan view showing a first substrate of a stator and a second substrate of a rotor provided in the resolver of FIG. 1 side by side. FIG. 2 is a plan view showing a first upper layer and a first lower layer of the stator side by side. FIG. 3 is a graph defining the number of turns of the first portion and the second portion of each of two excitation coils arranged in the stator of FIG. 3. FIG. 4 is a plan view showing a second upper layer and a second lower layer of the rotor of FIG. 2 side by side. FIG. 5 is a graph defining the number of windings of the outer circumferential portion and the inner circumferential portion of each of the upper layer coil and the lower layer coil arranged in the rotor of FIG. 6. FIG. 7 is a diagram (corresponding to FIG. 3) showing an example of the configuration of two-phase coils of a resolver according to a modified example.

[0013] A resolver according to an embodiment will be described with reference to the drawings. The following embodiment is merely an example, and is not intended to exclude various modifications and applications of techniques not explicitly described in the following embodiment. The configurations of the present embodiment can be modified in various ways without departing from the spirit of the invention.

[0014] The resolver of this embodiment is a detector (sensor) that detects the rotation angle of a rotor that rotates around a center line C relative to a stator. In the following description, the direction in which the center line C extends is defined as the axial direction (the direction of the rotation axis of the rotor), and the direction perpendicular to the axial direction, away from the center line C and toward the center line C, is defined as the radial direction. In addition, in the radial direction, the side of the center line C is defined as the radially inner side, and the opposite side (the side away from the center line C) is defined as the radially outer side. The direction perpendicular to the axial direction and going around the center line C is defined as the circumferential direction.

[0015] [1. Overall Configuration] Fig. 1 is a schematic diagram showing the configuration of a resolver 1 according to this embodiment. The resolver 1 includes a stator 2 and a rotor 3, and is a detector (sensor) that detects the rotation angle of the rotor 3 relative to the stator 2. The resolver 1 is applied to, for example, a servo motor (not shown). The stator 2 is a component that is fixed to a casing (not shown) of a device to which the resolver 1 is applied (for example, a servo motor or a device to which a servo motor is attached). The rotor 3 is a component that is rotatably supported (around a center line C) with respect to the stator 2, integrally with a shaft (not shown). The rotor 3 is disposed with a small gap G in a first axial direction Da1 relative to the stator 2. Hereinafter, the axial direction opposite to the first axial direction Da1 will be referred to as a second axial direction Da2.

[0016] The stator 2 and the rotor 3 each include a sheet-like substrate 21, 31. Each substrate 21, 31 is a thin sheet made of insulating resin (e.g., polyimide) and has a disk shape unfolded about a center line C, as shown in Fig. 2. Fig. 2 is a diagram showing the first substrate 21 of the stator 2 and the second substrate 31 of the rotor 3 side by side, as viewed from the gap G side between the stator 2 and the rotor 3.

[0017] In this embodiment, each of the substrates 21, 31 has two layers, an upper layer Lf and a lower layer Lb, stacked in the axial direction, as shown in Fig. 3 and Fig. 5. The first substrate 21 provided on the stator 2 has a first upper layer Lf1 located on the rotor 3 side (i.e., the first axial direction Da1 side) and a first lower layer Lb1 located on the side farther from the rotor 3 than the first upper layer Lf1 (i.e., the second axial direction Da2 side), as shown in Fig. 5. The second substrate 31 provided on the rotor 3 has a second upper layer Lf2 located on the stator 2 side (i.e., the second axial direction Da2 side) and a second lower layer Lb2 located on the side farther from the stator 2 than the second upper layer Lf2 (i.e., the first axial direction Da1 side), as shown in Fig. 5.

[0018] The upper layer Lf and the lower layer Lb are respectively provided on the surface of each substrate 21, 31 facing the gap G and on the surface facing away from the gap G. In Figures 3 and 5, the lower layer Lb is shown as seen through from the upper layer Lf (i.e., the gap G side).

[0019] 1, the stator 2 may be provided with a core 22 stacked on the second axial direction Da2 side of the first substrate 21, and a non-magnetic metal plate 23 covering the first substrate 21 and the core 22 from the second axial direction Da2 side. Similarly, the rotor 3 may be provided with a core 32 stacked on the first axial direction Da1 side of the second substrate 31, and a non-magnetic metal plate 33 covering the second substrate 31 and the core 32 from the first axial direction Da1 side.

[0020] As shown in Fig. 2, a plurality of coils 11 to 15 (sheet coils) are formed on each of the substrates 21 and 31. In other words, the resolver 1 is a sheet-type resolver having a plurality of sheet-shaped coils 11 to 15. These coils 11 to 15 are made of, for example, copper foil. By using sheet coils, it is possible to reduce the thickness of each of the coils 11 to 15, and ultimately to reduce the thickness of the resolver 1.

[0021] In this embodiment, a two-input, one-output (two-phase excitation, single-phase output) resolver 1 having a 1X axial multiplier angle is exemplified. The resolver 1 has two excitation coils 11, 12 (two-phase coils), a detection coil 13 (opposing coil), a transmission coil 14, and a reception coil 15. The resolver 1 also has, as the two excitation coils 11, 12, a sine excitation coil 11 and a cosine excitation coil 12 that transmit AC signals whose electrical phases differ by 90 degrees from each other. The sine excitation coil 11, cosine excitation coil 12, and detection coil 13 are all coils having a 1X axial multiplier angle and have magnetic properties that form a magnetic pole pair (north and south poles) when a current flows through them.

[0022] 1 and 2, the two excitation coils 11, 12 and the receiving coil 15 are provided on a first substrate 21 and electrically connected to the signal processing circuit 4. The detecting coil 13 and the transmitting coil 14 are provided on a second substrate 31 and electrically connected to each other (connected in series).

[0023] On the first substrate 21, the two excitation coils 11, 12 are arranged, for example, in the shape of a ring centered on a center line C and overlapped in the axial direction. Each excitation coil 11, 12 is configured to form two magnetic poles (one magnetic pole pair) facing in different directions when a current flows in the direction of the white arrows shown in Figures 2 and 3. The two excitation coils 11, 12 are also configured so that the centers of the magnetic poles are positioned alternately and equidistantly in the circumferential direction. Note that in Figures 2 and 3, for convenience, the sine excitation coil 11 is shown by a solid line and the cosine excitation coil 12 is shown by a dashed line.

[0024] 2, when a current flows in the direction of the solid white arrow, the sine excitation coil 11 is configured to form a magnetic pole facing the back of the paper (a magnetic pole marked with a cross (x) surrounded by a thin solid line, hereinafter referred to as an "S pole") and a magnetic pole facing the front of the paper (a magnetic pole marked with a dot (·) surrounded by a thin solid line, hereinafter referred to as an "N pole"), with the center line C interposed therebetween. In the following description of the two excitation coils 11 and 12, the 3 o'clock position on the paper of the stator 2 shown in FIGS. 2 and 3 is defined as the origin (0°) in the circumferential direction of the stator 2. The sine excitation coil 11 forms, for example, an S pole centered at the 90° position (12 o'clock on the paper) and an N pole centered at the 270° position (6 o'clock on the paper).

[0025] The cosine excitation coil 12 is configured such that, when a current flows in the direction of the dashed white arrow, it forms an S pole (a magnetic pole marked with an x ​​and surrounded by a thin dashed line) and an N pole (a magnetic pole marked with a dot and surrounded by a thin dashed line) on either side of a center line C. For example, the cosine excitation coil 12 forms an S pole centered at the 0° position (3 o'clock on the paper) and an N pole centered at the 180° position (9 o'clock on the paper).

[0026] In other words, the two excitation coils 11, 12 are configured so that, counterclockwise from the origin in the circumferential direction of the stator 2, the centers of the south pole of the cosine excitation coil 12, the south pole of the sine excitation coil 11, the north pole of the cosine excitation coil 12, and the north pole of the sine excitation coil 11 are positioned with a phase shift of 90° in this order. Note that, since each excitation coil 11, 12 is actually excited by an AC signal input from the signal processing circuit 4, the magnetic pole orientation (polarity) of each excitation coil 11, 12 is not constant but changes over time when the rotation angle of the rotor 3 is detected. The detailed configuration of the two excitation coils 11, 12 will be described later.

[0027] On the first substrate 21, the receiving coil 15 is formed, for example, radially inward of the two exciting coils 11, 12, with a conducting wire (conductor) arranged to spiral around the center line C.

[0028] On the second substrate 31, the detection coil 13 is, for example, in the shape of a ring centered on a center line C, and is disposed opposite the two excitation coils 11 and 12. The detection coil 13 is configured to form a magnetic pole pair of an south pole (magnetic pole marked with an x) and an north pole (magnetic pole marked with a dot) on either side of the center line C when a current flows in the direction of the black arrows shown in Figures 2 and 5. Note that the detection coil 13 actually generates an induced current when the magnetic fluxes of the excitation coils 11 and 12 interlink. Therefore, when detecting the rotation angle of the rotor 3, the detection coil 13 does not spontaneously form magnetic poles.

[0029] Therefore, strictly speaking, the detection coil 13 is configured to have magnetic properties that form south and north poles on either side of the center line C when a current flows in the direction of the black arrows shown in Figures 2 and 5. In the following description of the detection coil 13, unless otherwise specified, it is assumed that a current flows in the direction of the black arrows shown in Figures 2 and 5. Furthermore, in the following description of the detection coil 13, the 6 o'clock position of the rotor 3 shown in Figures 2 and 5 is defined as the origin (0°) in the circumferential direction of the rotor 3. The detection coil 13 forms, for example, a south pole centered at the 180° position (12 o'clock on the page) and a north pole centered at the 0° position (6 o'clock on the page).

[0030] As shown in Fig. 5, the detection coil 13 has an upper layer coil 16 (first coil) arranged in the second upper layer Lf2 (first layer) and a lower layer coil 17 (second coil) arranged in the second lower layer Lb2 (second layer). The detection coil 13 is configured so that, when a current flows, the magnetic fluxes formed by the upper layer coil 16 and the lower layer coil 17 interact to form the above-mentioned single magnetic pole pair. For convenience, in Fig. 2, the upper layer coil 16 is indicated by a solid line and the lower layer coil 17 is indicated by a dashed line. The detailed configuration of the detection coil 13 will be described later.

[0031] On the second substrate 31, the transmitting coil 14 is disposed opposite the receiving coil 15. The transmitting coil 14 is formed, for example, radially inward of the detecting coil 13, with a conductor wire arranged to spiral around the center line C.

[0032] The signal processing circuit 4 is an electric circuit provided at a position different from the stator 2 and the rotor 3, and as shown in Fig. 1, it incorporates a signal generation circuit 5 and a signal detection circuit 6. The signal generation circuit 5 generates an amplitude-modulated AC signal and inputs (supplies) it to the excitation coils 11 and 12. The signal detection circuit 6 outputs angle information corresponding to the rotation angle based on the AC signal returned from the receiving coil 15.

[0033] AC signals whose electrical angle phases differ by 90 degrees are input to the sine excitation coil 11 and the cosine excitation coil 12 from the signal generating circuit 5. More specifically, a cosine wave AC signal is input to the sine excitation coil 11, and a sine wave AC signal is input to the cosine excitation coil 12.

[0034] In the resolver 1, when an AC signal is input from the signal processing circuit 4 to the excitation coils 11 and 12, the excitation coils 11 and 12 are excited and generate magnetic flux (see the open arrows in FIG. 1 ). This magnetic flux interlinks with the detection coil 13 on the rotor 3 side, generating an induced voltage. As a result, the detection coil 13 generates a signal that is phase-modulated according to the rotation angle (relative angle) of the rotor 3 with respect to the stator 2. The signal transmitted from the detection coil 13 then excites the transmission coil 14 and generates magnetic flux (see the filled arrows in FIG. 1 ). This magnetic flux interlinks with the reception coil 15 on the stator 2 side, generating an induced voltage. The output waveform of this induced voltage is output to the signal processing circuit 4, and the rotation angle of the rotor 3 is calculated based on the phase change of the output waveform. In other words, the resolver 1 is a modulated-wave resolver that receives an amplitude-modulated AC signal and uses it to detect the rotation angle from the phase-modulated signal generated in the detection coil 13.

[0035] 2 to 4, the configuration of the two excitation coils 11, 12 will be described in detail. As described above, the two excitation coils 11, 12 are arranged on the first substrate 21, overlapping each other in the axial direction. This allows the excitation coils 11, 12 to be widely arranged (deployed) in the circumferential direction, and the excitation coils 11, 12 can be configured to form a magnetic flux distribution with little distortion over a wide range in the circumferential direction. Therefore, a detection signal (phase-modulated signal) corresponding to the rotation angle of the rotor 3 is obtained by the detection coil 13, improving the detection accuracy of the resolver 1. Note that a magnetic flux distribution with little distortion here means a magnetic flux distribution in which there are few locations in the circumferential direction where magnetic coupling between the excitation coils 11, 12 and the detection coil 13 is lost and where there are no sudden changes in magnetic flux.

[0036] Here, the axial positions of the first upper layer Lf1 and the first lower layer Lb1 are slightly different on the first substrate 21. For this reason, it is assumed that the two excitation coils 11, 12 are stacked on the first substrate 21, for example, with the sine excitation coil 11 arranged on the first upper layer Lf1 and the cosine excitation coil 12 arranged on the first lower layer Lb1. In this case, a slight difference in the axial positions of the layers Lf1, Lb1 causes a magnetic resistance difference (impedance difference) between the sine excitation coil 11 and the cosine excitation coil 12 with respect to the detection coil 13, and the detection accuracy of the resolver 1 may be reduced.

[0037] Therefore, each of the two excitation coils 11, 12 is provided with a configuration that suppresses the impedance difference between the two excitation coils 11, 12. Specifically, as shown in Fig. 3, each of the two excitation coils 11, 12 is provided with a first portion 11f, 12f arranged on a first upper layer Lf1 (common layer, upper layer) and a second portion 11b, 12b arranged on a first lower layer Lb1 (layer other than the common layer, lower layer), and the first portion 11f and the second portion 11b, and the first portion 12f and the second portion 12b are combined to form one magnetic pole. Each of the first portions 11f, 12f extends in a first circumferential direction Dc1 (e.g., clockwise direction, first direction) circumferentially around the center of the corresponding magnetic pole. Furthermore, each second portion 11b, 12b extends in a second circumferential direction Dc2 (e.g., a counterclockwise direction, a second direction) opposite to the first circumferential direction Dc1 based on the center of the respective magnetic pole, and is stacked on a first portion 12f, 11f of the excitation coil 12, 11 of a different (other) phase from the excitation coil 11, 12 that forms the magnetic pole.

[0038] In this embodiment, each excitation coil 11, 12 forms two magnetic poles, an S pole and an N pole. Therefore, each excitation coil 11, 12 has two first portions 11f, 12f and two second portions 11b, 12b. The sine excitation coil 11 has an S-pole first portion 11fs and an S-pole second portion 11bs as portions that form the S pole, and an N-pole first portion 11fn and an N-pole second portion 11bn as portions that form the N pole. The cosine excitation coil 12 has an S-pole first portion 12fs and an S-pole second portion 12bs as portions that form the S pole, and an N-pole first portion 12fn and an N-pole second portion 12bn as portions that form the N pole.

[0039] Hereinafter, the center position of the south pole of the sine excitation coil 11 (90° position) will be referred to as the first south pole center position Pcs1, and the center position of the north pole of the sine excitation coil 11 (270° position) will be referred to as the first north pole center position Pcn1. The first south pole center position Pcs1 and the first north pole center position Pcn1 will also be collectively referred to as the first center position Pc1. The center position of the south pole of the cosine excitation coil 12 (0° position) will be referred to as the second south pole center position Pcs2, and the center position of the north pole of the cosine excitation coil 12 (180° position) will be referred to as the second north pole center position Pcn2. The second south pole center position Pcs2 and the second north pole center position Pcn2 will also be collectively referred to as the second center position Pc2.

[0040] The south pole first portion 11fs, which forms the south pole of the sine excitation coil 11, has a quadrant ring shape (partial ring shape) extending from the first south pole center position Pcs1 to, for example, near a position (0°) where the phase differs by 90° in the first circumferential direction Dc1 (shorter than this position). The south pole second portion 11bs has a quadrant ring shape extending from the first south pole center position Pcs1 to, for example, near a position (180°) where the phase differs by 90° in the second circumferential direction Dc2 (same position). The south pole second portion 11bs is stacked on the north pole first portion 12fn of the cosine excitation coil 12.

[0041] The N-pole first portion 11fn, which forms the N-pole of the sine excitation coil 11, has a quadrant ring shape extending, for example, to a position (180°) where the phase differs by 90° in the first circumferential direction Dc1 based on the first N-pole center position Pcn1. The N-pole second portion 11bn has a quadrant ring shape extending, for example, to a position (0°) where the phase differs by 90° in the second circumferential direction Dc2 based on the position Pcn1, and is stacked on the S-pole first portion 12fs of the cosine excitation coil 12.

[0042] Similarly, the S-pole first portion 12fs, which forms the S-pole of the cosine excitation coil 12, has a quadrant ring shape extending, for example, to near a position (270°) where the phase differs by 90° in the first circumferential direction Dc1, based on the second S-pole center position Pcs2. The S-pole second portion 12bs has a quadrant ring shape extending, for example, to near a position (90°) where the phase differs by 90° in the second circumferential direction Dc2, based on the position Pcs2, and is stacked on the S-pole first portion 11fs of the sine excitation coil 11.

[0043] The N-pole first portion 12fn, which forms the N-pole of the cosine excitation coil 12, has a quadrant ring shape extending, for example, to a position (90°) where the phase differs by 90° in the first circumferential direction Dc1 based on the second N-pole center position Pcn2. The N-pole second portion 12bn has a quadrant ring shape extending, for example, to a position (270°) where the phase differs by 90° in the second circumferential direction Dc2 based on the position Pcn2, and is stacked on the N-pole first portion 11fn of the sine excitation coil 11.

[0044] When a portion forming one magnetic pole is composed of two portions provided on different layers Lf1 and Lb1 as described above, the portion must have a connection point that penetrates the first substrate 21 and electrically connects the portions 11f and 12f provided on the first upper layer Lf1 with the portions 11b and 12b provided on the first lower layer Lb1. However, such connection points are prone to variations in the resistance of the conductor due to manufacturing reasons (e.g., etching and plating processes). Such variations in the resistance of the connection points are caused by variations in the wiring resistance of the excitation coils 11 and 12, which can easily lead to differences in wiring resistance between the two excitation coils 11 and 12.

[0045] Therefore, each of the two excitation coils 11, 12 is provided with a configuration that suppresses the above-mentioned difference in wiring resistance. Specifically, the first portions 11f, 12f and the second portions 11b, 12b of each excitation coil 11, 12 are formed into a substantially closed shape by winding conductor wires W11, W12 (first conductor wires) around the center positions Pc1, Pc2 of the respective magnetic poles, and the first portions 11f, 12f and the second portions 11b, 12b that form one magnetic pole are electrically connected via single through holes 11h, 12h (connection points). This minimizes the number of connection points for the parts that form one magnetic pole, thereby suppressing differences in wiring resistance caused by variations in the resistance values ​​of the connection points. The conductor W11 forming the portions 11f and 11b of the sine excitation coil 11 and the conductor W12 forming the portions 12f and 12b of the cosine excitation coil 12 are separate conductors and are not electrically connected to each other.

[0046] A detailed description will be given focusing on the sine excitation coil 11. The first portion 11f and the second portion 11b of the sine excitation coil 11 are formed, for example, by routing the conductor W11 so as to surround (circumnavigate) the first central position Pc1, thereby forming a substantially closed shape. Note that the term "substantially closed shape" as used here means a shape in which the conductor W11 is present all around the first central position Pc1 of the magnetic pole, and does not mean a shape in which the conductor W11 is absent in part of the periphery of the first central position Pc1, such as a U-shape or a C-shape.

[0047] Each of the portions 11f, 11b of the sine excitation coil 11 may be formed, for example, as shown in the figure, by winding a single conductor W11 in a spiral (snake pattern) around the first center position Pc1 in each of the layers Lf1, Lb1. In this way, each of the portions 11f, 11b may be formed by the conductor W11 that is continuously arranged without interruption in a single stroke in each of the layers Lf1, Lb1. Each of the portions 11f, 11b forms a magnetic pole in an inner region of the winding of the conductor W11 (the region indicated by dotted lines in FIG. 3).

[0048] Furthermore, in this embodiment, the first portion 11f and the second portion 11b are wound so that the number of turns decreases as the distance from the first center position Pc1 increases. That is, the conductor W11 forming each portion 11f, 11b is wound in one direction in a partially annular shape from a start point (through hole 11h) near the first center position Pc1, and is wound so that the end point is on the outer side of the winding, and the turned-back portion on the opposite side to the first center position Pc1 is thinner than the turned-back portion on the first center position Pc1 side. The above description has focused on the sine excitation coil 11, but for the cosine excitation coil 12, the conductor W12 is similarly wound around the second center position Pc2 to form the first portion 12f and the second portion 12b.

[0049] The conductors W11 and W12 are arranged in the first portions 11f and 12f and the second portions 11b and 12b, respectively, so that the number of turns thereof satisfies the relationship shown in the graph of Fig. 4. Fig. 4 is a graph defining the number of turns M of each of the portions 11f, 11b, 12f, and 12b in the circumferential direction, with the horizontal axis corresponding to the circumferential angle shown in Fig. 3 and the vertical axis corresponding to the number of turns M of each of the portions 11f, 11b, 12f, and 12b. On the vertical axis, the "(S)" side corresponds to the number of turns M of the portions 11fs, 12fs, 11bs, and 12bs that form the south pole, and the "(N)" side corresponds to the number of turns M of the portions 11fn, 12fn, 11bn, and 12bn that form the north pole.

[0050] 4, for convenience, the portions 11fs, 11fn, 12fs, and 12fn arranged on the first upper layer Lf1 are indicated by thicker lines than the portions 11bs, 11bn, 12bs, and 12bn arranged on the first lower layer Lb1. Furthermore, the portions 11fs, 11fn, 11bs, and 11bn of the sine excitation coil 11 are indicated by solid lines, and the portions 12fs, 12fn, 12bs, and 12bn of the cosine excitation coil 12 are indicated by dashed lines.

[0051] 4, the number of turns M of the S-pole first portion 11fs of the sine excitation coil 11 increases from near 0° to near 90°, and is set to a maximum value (5 in this case) near 90°, i.e., near the first S-pole center position Pcs1. The number of turns M of the S-pole second portion 11bs of the sine excitation coil 11 is set symmetrically to the S-pole first portion 11fs, decreasing from near 90° to near 180°.

[0052] The N-pole first portion 11fn of the sine excitation coil 11 is set so that the number of turns M increases from around 180° to around 270° and reaches a maximum value (5 in this case) around 270°, i.e., around the first N-pole center position Pcn1. The N-pole second portion 11bn of the sine excitation coil 11 is set so that the number of turns M decreases from around 270° to around 360°, symmetrically with the N-pole first portion 11fn.

[0053] In the sinusoidal excitation coil 11, the number of turns M of each of the portions 11fs, 11bs, 11fn, and 11bn is set so as to approximate a sinusoidal waveform with one cycle per circumferential revolution, as described above. As a result, when the sinusoidal excitation coil 11 is excited, a magnetic flux distribution is formed in accordance with the change in the number of turns M of each of the portions 11fs, 11bs, 11fn, and 11bn, i.e., a sinusoidal magnetic flux distribution, and therefore a magnetic flux distribution with little distortion is obtained.

[0054] The number of turns M of the S-pole second portion 12bs of the cosine excitation coil 12 is set to be maximum (5 in this case) near 0°, i.e., near the second S-pole center position Pcs2, and decreases from near 0° to near 90°. The number of turns M of the S-pole first portion 12fs of the cosine excitation coil 12 is set symmetrically to the S-pole second portion 12bs, and decreases from near 0° to near −90° (270°).

[0055] The N-pole first portion 12fn of the cosine excitation coil 12 is set so that the number of turns M increases from around 90° to around 180° and reaches a maximum value (5 in this case) around 180°, i.e., around the second N-pole center position Pcn2. The N-pole second portion 12bn of the cosine excitation coil 12 is set so that the number of turns M decreases from around 180° to around 270°, symmetrically with the N-pole first portion 12fn.

[0056] In the cosine excitation coil 12, the number of turns M of each of the portions 12bs, 12fn, 12bn, and 12fs is set so as to approximate a cosine waveform in which one cycle corresponds to one circumferential revolution, as described above. As a result, when the cosine excitation coil 12 is excited, a magnetic flux distribution is formed in accordance with the change in the number of turns M of each of the portions 12bs, 12fn, 12bn, and 12fs, i.e., a cosine waveform magnetic flux distribution, and therefore a magnetic flux distribution with little distortion is obtained.

[0057] In this embodiment, the first portions 11f, 12f and the second portions 11b, 12b, which respectively form one magnetic pole, have the same number of turns (maximum number of turns). However, the first portions 11f, 12f and the second portions 11b, 12b may have different numbers of turns. For example, the number of turns of the first portions 11f, 12f may be set to be less than the number of turns of the second portions 11b, 12b. This suppresses the impedance difference between the first portions 11f, 12f and the second portions 11b, 12b, which occurs due to the difference in the axial positions of the layers Lf1, Lb1.

[0058] 2 and 3, the radial widths of the first portions 11f, 12f and the second portions 11b, 12b, which respectively form one magnetic pole, are approximately equal. However, the radial widths of the first portions 11f, 12f and the second portions 11b, 12b may be different. For example, the radial width of the first portions 11f, 12f may be smaller than the radial width of the second portions 11b, 12b. In other words, the area of ​​the region where the magnetic pole is formed in the first portions 11f, 12f may be smaller than the area of ​​the region where the magnetic pole is formed in the second portions 11b, 12b. This suppresses the impedance difference between the first portions 11f, 12f and the second portions 11b, 12b, which occurs due to the difference in the axial positions of the layers Lf1, Lb1.

[0059] 2, 5, and 6, the configuration of the detector coil 13 will be described in detail below. As described above, the detector coil 13 has an upper layer coil 16 and a lower layer coil 17, and the magnetic fluxes of the upper layer coil 16 and the lower layer coil 17 interact with each other to form magnetic poles (south pole and north pole) oriented in different directions. Hereinafter, the center position of the south pole of the detector coil 13 (the position at 180° of the rotor 3 shown in FIGS. 2 and 5) will be referred to as a third south pole center position Pcs3, and the center position of the north pole of the detector coil 13 (the position at 0° of the rotor 3 shown in FIGS. 2 and 5) will be referred to as a third north pole center position Pcn3.

[0060] 5, the detection coil 13 is formed by a conductor W13 (second conductor) arranged in the second upper layer Lf2 and the second lower layer Lb2. The conductor W13 forming the detection coil 13 is a conductor of a different system from the conductors W11 and W12 forming the excitation coils 11 and 12, and is not electrically connected to these conductors W11 and W12.

[0061] The upper layer coil 16 is a generally annular coil formed by winding the upper layer conductor Wf, which is disposed in the second upper layer Lf2 (first layer) of the conductor W13, in a first circumferential direction Dc1 (first direction) starting from a radially outer end point. The lower layer coil 17 is a generally annular coil formed by winding the lower layer conductor Wb, which is disposed in the second lower layer Lb2 (second layer) of the conductor W13, in a second circumferential direction Dc2 (second direction) starting from a radially inner end point. The upper layer conductor Wf and the lower layer conductor Wb are wound around the center line C at least two or more times (multiple times) without turning back in the direction opposite to their respective winding directions (the first circumferential direction Dc1 and the second circumferential direction Dc2). The upper layer conductor Wf and the lower layer conductor Wb are electrically connected to each other via the through holes 13h, thereby being continuously provided.

[0062] 5 indicates the routing direction of the conductor W13 when the upper layer conductor Wf and the lower layer conductor Wb are routed in this order, starting from the outer end point of the winding of the upper layer conductor Wf (i.e., the position of the black arrow in FIG. 5). This thin arrow can also be said to be the direction of current flow when current flows in the direction of the black arrow in FIG.

[0063] Each of the upper coil 16 and the lower coil 17 has an outer circumferential portion 16o, 17o and an inner circumferential portion 16i, 17i, which form two magnetic poles oriented in different directions. Each of the outer circumferential portions 16o, 17o extends in the circumferential direction near the outer circumferential edge of the upper coil 16 and the lower coil 17, which are substantially annular in shape. Each of the inner circumferential portions 16i, 17i extends in the circumferential direction radially inward of each of the outer circumferential portions 16o, 17o.

[0064] The upper-layer outer circumferential portion 16o of the upper-layer coil 16 is arranged so as not to overlap partially with the upper-layer inner circumferential portion 16i of the upper-layer coil 16 in the circumferential direction, and is arranged at approximately the same circumferential position as the lower-layer inner circumferential portion 17i of the lower-layer coil 17. Similarly, the lower-layer outer circumferential portion 17o of the lower-layer coil 17 is arranged so as not to overlap partially with the lower-layer inner circumferential portion 17i in the circumferential direction, and is arranged at approximately the same circumferential position as the upper-layer inner circumferential portion 16i.

[0065] In this embodiment, the upper layer outer peripheral portion 16o extends in both circumferential directions (first circumferential direction Dc1 and second circumferential direction Dc2) based on the third N pole center position Pcn3, except for the area around the third S pole center position Pcs3 in the circumferential direction. The lower layer inner peripheral portion 17i is located adjacent to the radially inward side of the upper layer outer peripheral portion 16o. The upper layer inner peripheral portion 16i extends in both circumferential directions based on the third S pole center position Pcs3, except for the area around the third N pole center position Pcn3 in the circumferential direction. As a result, the upper layer outer peripheral portion 16o and the upper layer inner peripheral portion 16i are arranged so as not to overlap partially in the circumferential direction around the third N pole center position Pcn3 and the third S pole center position Pcs3.

[0066] In this way, since upper layer outer peripheral portion 16o is provided on the third N-pole central position Pcn3 side and upper layer inner peripheral portion 16i is provided on the third S-pole central position Pcs3 side, upper layer coil 16 can also be said to be eccentric toward the third N-pole central position Pcn3 side with respect to center line C. When current flows in the direction of the black arrow shown in Figure 5, upper layer coil 16 generates an N-pole magnetic flux in a substantially circular upper layer region Rf (the region shown by dark dots in Figure 5) that is developed around a position closer to the third N-pole central position Pcn3 than the center line C.

[0067] The same applies to the lower layer coil 17. That is, the lower layer outer peripheral portion 17o extends in both circumferential directions with the third south pole center position Pcs3 as the reference, except for the area around the third north pole center position Pcn3 in the circumferential direction. The upper layer inner peripheral portion 16i is located adjacent to the radially inward side of the lower layer outer peripheral portion 17o. The lower layer inner peripheral portion 17i extends in both circumferential directions with the third north pole center position Pcn3 as the reference, except for the area around the third south pole center position Pcs3 in the circumferential direction. As a result, the lower layer outer peripheral portion 17o and the lower layer inner peripheral portion 17i are arranged so as not to overlap partially in the circumferential direction around the third north pole center position Pcn3 and the third south pole center position Pcs3.

[0068] In this way, since lower layer outer peripheral portion 17o is provided on the third S-pole central position Pcs3 side and lower layer inner peripheral portion 17i is provided on the third N-pole central position Pcn3 side, lower layer coil 17 can be said to be eccentric toward the third S-pole central position Pcs3 side with respect to center line C. When a current flows in the direction of the black arrow shown in Figure 5, lower layer coil 17 generates an S-pole magnetic flux in a substantially circular lower layer region Rb (the region shown by light dotted lines in Figure 5) that is centered at a position closer to the third S-pole central position Pcs3 than the center line C.

[0069] In the detection coil 13, when a current flows in the direction of the black arrows shown in Figures 2 and 5, the magnetic fluxes of the upper layer coil 16 and the lower layer coil 17 interact with each other. As a result, in the region radially inward of the inner circumferential portions 16i and 17i, the magnetic fluxes of the upper layer coil 16 and the lower layer coil 17 cancel each other out, and as shown in Figure 2, magnetic poles of different orientations are formed between the upper outer circumferential portion 16o and the lower inner circumferential portion 17i, and between the upper inner circumferential portion 16i and the lower outer circumferential portion 17o. More specifically, an N pole is formed in a semicircular ring-shaped region (indicated by thick dots in Figure 2) centered on the third N pole central position Pcn3 between the upper outer circumferential portion 16o and the lower inner circumferential portion 17i, and an S pole is formed in a semicircular ring-shaped region (indicated by light dots in Figure 2) centered on the third S pole central position Pcs3 between the upper inner circumferential portion 16i and the lower outer circumferential portion 17o.

[0070] 5, the upper-layer outer peripheral portion 16o is formed by a plurality of outer windings Wfo of the upper-layer conductor Wf, which extend in both circumferential directions based on the third north-pole center position Pcn3. The upper-layer inner peripheral portion 16i is formed by a plurality of inner windings Wfi of the upper-layer conductor Wf, which extend in both circumferential directions based on the third south-pole center position Pcs3. The number of windings Wfo, Wfi forming each of the upper-layer outer peripheral portion 16o and the upper-layer inner peripheral portion 16i decreases with increasing distance from the respective magnetic pole centers Pcn3, Pcs3.

[0071] Furthermore, in this embodiment, the upper layer conductor Wf is provided with a plurality of connection wires Wfc that connect the plurality of outer windings Wfo and the plurality of inner windings Wfi. The upper layer conductor Wf is arranged so that, for each turn around the center line C, an outer winding Wfo, an inner winding Wfi, and two connection wires Wfc that connect the ends of these windings Wfo, Wfi are formed.

[0072] For example, the upper layer conductor Wf is routed starting from a position near the third north-pole center position Pcn3 and radially outward of the position where the upper layer outer peripheral portion 16o is formed, and extending in the first circumferential direction Dc1 to form the outer winding Wfo. Then, just before reaching the third south-pole center position Pcs3, the upper layer conductor Wf is bent radially inward to form one connection line Wfc, the inner winding Wfi, and the other connection line Wfc, in that order. More specifically, the upper layer conductor Wf is routed radially inward to form one connection line Wfc, then in the first circumferential direction Dc1 to form the inner winding Wfi, and then in the radially outward to form the other connection line Wfc. The upper layer conductor Wf is thus routed around the third south-pole center position Pcs3, cutting out a portion of the outer circle along which the outer winding Wfo extends. In this embodiment, the connection wires Wfc extend in the radial direction as shown in the figure, but the connection wires Wfc may extend in a direction inclined relative to the radial direction. For example, one of the connection wires Wfc may be arranged to extend radially inward in the first circumferential direction Dc1, and the other connection wire Wfc may be arranged to extend radially outward in the first circumferential direction Dc1. The upper-layer conductor Wf is then arranged again in the first circumferential direction Dc1 to form the outer winding wire Wfo. When passing near the third N-pole center position Pcn3, the upper-layer conductor Wf is arranged slightly radially inward of the previous outer winding wire Wfo, and this process is repeated.

[0073] The upper layer conductor Wf is arranged so that the circumferential width of the notch formed by the pair of connecting wires Wfc and the inner winding Wfi increases with each turn around the center line C. As a result, both the upper layer outer peripheral portion 16o and the upper layer inner peripheral portion 16i are configured so that the number of windings Wfo, Wfi decreases as they move away from the center positions Pcn3, Pcs3 of the respective magnetic poles.

[0074] In this embodiment, to shift the phase between the circumferential position of the connection wire Wfc of the upper-layer conductor Wf and the circumferential position of the connection wire Wbc of the lower-layer conductor Wb (described later), the entire upper coil 16 is tilted at a predetermined angle in the first circumferential direction Dc1 with respect to a diameter line connecting the third south-pole center position Pcs3 and the third north-pole center position Pcn3. Specifically, the outer winding Wfo extends on both sides of the circumferential direction, with a first offset position P1 offset by a predetermined angle in the first circumferential direction Dc1 from the third north-pole center position Pcn3 as its center. The inner winding Wfi extends on both sides of the circumferential direction, with a second offset position P2 offset by a predetermined angle in the first circumferential direction Dc1 from the third south-pole center position Pcs3 as its center. The predetermined angle may be set depending on the maximum number of windings Wfo and Wfi.

[0075] The lower-layer outer peripheral portion 17o is formed by a plurality of outer windings Wbo of the lower-layer conductor Wb that extend in both circumferential directions based on the third south-pole center position Pcs3. The lower-layer inner peripheral portion 17i is formed by a plurality of inner windings Wbi of the lower-layer conductor Wb that extend in both circumferential directions based on the third north-pole center position Pcn3. The plurality of windings Wbo, Wbi that form the lower-layer outer peripheral portion 17o and the lower-layer inner peripheral portion 17i, respectively, are set so that the number of windings Wbo, Wbi decreases with increasing distance from the respective magnetic pole center positions Pcs3, Pcn3, similar to the windings Wfo, Wfi of the upper-layer outer peripheral portion 16o and the upper-layer inner peripheral portion 16i.

[0076] Furthermore, in this embodiment, the lower conductor Wb is provided with a plurality of connection wires Wbc connecting the plurality of outer windings Wbo and the plurality of inner windings Wbi, similar to the upper conductor Wf. The lower conductor Wb is arranged so that, for each turn around the center line C, an outer winding Wbo, an inner winding Wbi, and two connection wires Wbc connecting the ends of these windings Wbo and Wbi are formed.

[0077] The lower-layer conductor Wb is routed, for example, from a position (the position of the through-hole 13h) near the third north-pole center position Pcn3 and radially inward of the position where the lower-layer inner circumferential portion 17i is formed, toward the second circumferential direction Dc2 to form the inner winding Wbi. Then, just before reaching the third south-pole center position Pcs3, the lower-layer conductor Wb is bent radially outward to form one connection line Wbc, the outer winding Wbo, and the other connection line Wbc in this order. More specifically, the lower-layer conductor Wb is routed radially outward to form one connection line Wbc, then in the second circumferential direction Dc2 to form the outer winding Wbo, and finally inward to form the other connection line Wbc. The lower-layer conductor Wb is thus routed so as to protrude from a portion of the inner circle around the third north-pole center position Pcn3, along which the inner winding Wbi extends. In this embodiment, the connection wires Wbc extend in the radial direction as shown in the figure, but the connection wires Wbc may extend in a direction inclined relative to the radial direction. For example, one of the connection wires Wbc may be arranged to extend radially outward in the second circumferential direction Dc2, and the other connection wire Wbc may be arranged to extend radially inward in the second circumferential direction Dc2. The lower-layer conductor Wb is then arranged again in the second circumferential direction Dc2 to form the inner winding Wbi. When passing near the third N-pole center position Pcn3, the lower-layer conductor Wb is arranged slightly radially outward of the previous inner winding Wbi, and this process is repeated.

[0078] The lower layer conductor Wb is arranged so that the circumferential width of the protruding portion, which is made up of the pair of connecting wires Wbc and the outer winding Wbo, increases with each turn around the center line C. As a result, both the lower layer outer peripheral portion 17o and the lower layer inner peripheral portion 17i are configured so that the number of windings Wbo, Wbi decreases with increasing distance from the center positions Pcs3, Pcn3 of the magnetic poles.

[0079] In this embodiment, the entire lower layer coil 17 is disposed opposite the upper layer coil 16, tilted at a predetermined angle in the second circumferential direction Dc2 with respect to a diameter line connecting the third south pole center position Pcs3 and the third north pole center position Pcn3. Specifically, the outer winding Wbo extends on both sides of the circumferential direction around a third offset position P3, which is offset by a predetermined angle in the second circumferential direction Dc2 from the third south pole center position Pcs3. The inner winding Wbi extends on both sides of the circumferential direction around a fourth offset position P4, which is offset by a predetermined angle in the second circumferential direction Dc2 from the third north pole center position Pcn3. As a result, the circumferential positions of the connection lines Wfc of the upper layer conductors Wf and the connection lines Wbc of the lower layer conductors Wb are arranged with a phase shift so that they alternate in the circumferential direction, as shown in FIG. 2 . The predetermined angle of the lower layer coil 17 may be set according to the maximum number of windings Wbo, Wbi. The predetermined angle of the upper layer coil 16 may be the same as or different from the predetermined angle of the lower layer coil 17.

[0080] The numbers of windings Wfo, Wfi, Wbo, and Wbi in each of the outer circumferential portions 16o, 17o and the inner circumferential portions 16i, 17i in the circumferential direction are set to satisfy the relationship of the numbers shown in the graph of Fig. 6. Fig. 6 is a graph that defines the number m of windings Wfo, Wfi, Wbo, and Wbi in each of the portions 16o, 16i, 17o, and 17i in the circumferential direction.

[0081] In the graph of Fig. 6, the horizontal axis corresponds to the angle in the circumferential direction shown in Fig. 5. The vertical axis on the left corresponds to the number m of the windings Wfo, Wfi, Wbo, and Wbi. On the vertical axis on the left, the "(S)" side corresponds to the number m of the windings Wfi and Wbo that form the south pole, and the "(N)" side corresponds to the number m of the windings Wfo and Wbi that form the north pole. For convenience, in Fig. 6, the outer windings Wfo and Wbo are indicated by thicker lines than the inner windings Wfi and Wbi. The windings Wfo and Wfi of the upper conductor Wf are indicated by solid lines, and the windings Wbo and Wbi of the lower conductor Wb are indicated by dashed lines.

[0082] 6, the vertical axis on the right side corresponds to the number of turns M of the south pole and north pole formed in the detection coil 13 by the interaction of the portions 16o, 16i, 17o, and 17i. On the vertical axis on the right side, the "(S)" side corresponds to the number of turns M of the south pole, and the "(N)" side corresponds to the number of turns M of the north pole.

[0083] 6, the number m of the inner winding Wfi of the upper-layer conductor Wf and the outer winding Wbo of the lower-layer conductor Wb is set to a maximum value (5 in this case) near 180°, i.e., near the third S-pole center position Pcs3. The number m decreases as the distance from the 180° position increases, and the number m is set to a minimum value (0 in this case) near 0° (360°).

[0084] Conversely, the number m of the outer winding Wfo of the upper-layer conductor Wf and the inner winding Wbi of the lower-layer conductor Wb is set to a maximum value (5 in this case) near 0° (360°), i.e., near the third north-pole center position Pcn3. The number m decreases as the angle moves away from the 0° position, and is set to a minimum value (0 in this case) near 180°.

[0085] By setting the number m of each of the windings Wfo, Wfi, Wbo, and Wbi as described above, the number of turns M changes in a cosine waveform, with one cycle per circumferential revolution, as shown by the dotted waveform, in the detection coil 13. In other words, the detection coil 13 changes in the number of turns in a sine waveform, with one cycle occurring between the S and N poles, starting from the 90° position, which is the boundary between the S and N poles.

[0086] As a result, when a current flows through the detection coil 13, a magnetic flux distribution corresponding to the change in the number of turns of the detection coil 13, i.e., a sinusoidal magnetic flux distribution, is formed, thereby obtaining a magnetic flux distribution with little distortion. In other words, by setting the number m of each of the windings Wfo, Wfi, Wbo, and Wbi so that the dotted waveform, which is a composite wave of the lines (waveforms) of the windings Wfo, Wfi, Wbo, and Wbi, approximates a sinusoidal waveform with one cycle per circumferential turn (between the south and north poles), the detection coil 13 can be provided with magnetic properties that form a sinusoidal magnetic flux distribution with little distortion between the south and north poles.

[0087] In this embodiment, since the connecting wires Wfc, Wbc extend in the radial direction as described above, the step positions of the waveforms representing the windings Wfo, Wfi, Wbo, and Wbi correspond to the positions of the connecting wires Wfc, Wbc. As such, the graph in Figure 6 also shows the positions of the connecting wires Wfc, Wbc, and can be said to be a graph that defines the positional relationship of the connecting wires Wfc, Wbc in the circumferential direction.

[0088] The detection coil 13 has a plurality of connecting wires Wfc, Wbc set (routed) so as to pass through circumferential positions that form a sinusoidal magnetic flux distribution that forms one cycle between the south pole and the north pole, that is, the step positions of the waveforms of the windings Wfo, Wfi, Wbo, and Wbi shown in FIG. 6. This results in a change in the number of turns of the waveform shown by dotted lines in FIG. 6, and suppresses distortion of the magnetic flux distribution when current flows.

[0089] The number of turns M of the detection coil 13 changes at the step positions, and the magnitude of the magnetic flux changes in accordance with this change in the number of turns M. Therefore, the step positions can also be referred to as magnetic flux change positions. Even when the connection wires Wfc, Wbc extend at an inclination relative to the radial direction, the detection coil 13 is configured so that the connection wires Wfc, Wbc pass through the magnetic flux change positions, thereby suppressing distortion of the magnetic flux distribution when a current flows. The magnetic flux change positions may be set based on the circumferential length between a pair of magnetic poles and the maximum number m of the windings Wfo, Wfi, Wbo, and Wbi. When the connection wires Wfc, Wbc extend at an inclination relative to the radial direction, the connection wires Wfc, Wbc are preferably configured to pass through the magnetic flux change positions and at an inclination that makes the step-like steps in FIG. 6 slope. This allows the dotted waveform, which is a composite wave of the waveforms of the windings Wfo, Wfi, Wbo, and Wbi, to change more smoothly, resulting in a waveform that more closely resembles a sine waveform, thereby suppressing distortion of the magnetic flux distribution (especially sudden changes in the magnetic flux).

[0090] Furthermore, in this embodiment, due to the arrangement (inclination) relationship between the upper layer coil 16 and the lower layer coil 17, the inner winding Wfi of the upper layer conductor Wf and the outer winding Wbo of the lower layer conductor Wb are shifted in phase by the difference between the second shift position P2 and the third shift position P3. The outer winding Wfo of the upper layer conductor Wf and the inner winding Wbi of the lower layer conductor Wb are shifted in phase by the difference between the first shift position P1 and the fourth shift position P4.

[0091] Therefore, the positions (step positions, magnetic flux change positions) of the connecting wires Wfc of the upper conductor Wf and the positions (step positions, magnetic flux change positions) of the connecting wires Wbc of the lower conductor Wb are shifted from each other by the above-mentioned phase difference. Because the circumferential positions through which the connecting wires Wfc of the upper conductor Wf pass and the circumferential positions through which the connecting wires Wbc of the lower conductor Wb pass are shifted in phase, the steps of the dotted waveform become finer. Therefore, a waveform that more closely resembles a sinusoidal waveform is obtained, thereby suppressing distortion of the magnetic flux distribution (especially sudden changes in magnetic flux).

[0092] [4. Actions and Effects] (1) In the resolver 1 described above, each of the two excitation coils 11, 12 arranged on the first substrate 21 has a first portion 11f, 12f and a second portion 11b, 12b as a portion that forms one magnetic pole. The first portions 11f, 12f are arranged on the first upper layer Lf1 of the first substrate 21. The second portions 11b, 12b are arranged on a layer (first lower layer Lb1) different from the first upper layer Lf1 of the first substrate 21, and are stacked with the first portions 12f, 11f of the coils 12, 11 of a phase different from the coils 11, 12 having the second portions 11b, 12b.

[0093] In this way, by arranging the two excitation coils 11, 12 overlapping in the axial direction, each of the two excitation coils 11, 12 can be widely deployed in the circumferential direction on the first substrate 21, and any magnetic flux distribution with little distortion (particularly, a magnetic flux distribution with few locations where magnetic coupling is lost) can be formed in each excitation coil 11, 12. Furthermore, at least in the first portions 11f, 12f, the axial positional relationship (axial distance) between the two excitation coils 11, 12 and the detection coil 13 is equal, so the impedance difference between the two excitation coils 11, 12 can be reduced.

[0094] Furthermore, in the resolver 1 described above, the first portions 11f, 12f and the second portions 11b, 12b, which form one magnetic pole, each have a substantially closed shape formed by winding the conductor wires W11, W12 around the center position Pc of the magnetic pole, and are electrically connected to each other via a single through-hole 11h, 12h. This reduces the difference in wiring resistance between the two excitation coils 11, 12 compared to a configuration in which the first portions 11f, 12f and the second portions 11b, 12b are connected via multiple through-holes. Furthermore, since it is not necessary to distort the shape of each excitation coil 11, 12 to provide multiple through-holes, distortion of the magnetic flux distribution is also reduced. This improves the detection accuracy of the resolver 1.

[0095] (2) The first portions 11f, 12f and the second portions 11b, 12b are formed by the conductor wires W11, W12 that are continuously arranged in the layers Lf1, Lf2, respectively. This allows magnetic poles to be formed inside the windings of the conductor wires W11, W12 with a simple configuration.

[0096] (3) In the resolver 1 described above, the first portions 11f, 12f and the second portions 11b, 12b are wound so that the number of turns M decreases as the distance from the center position Pc of each magnetic pole increases. This allows a magnetic flux distribution with a peak at the center position Pc of the magnetic pole to be obtained with a simple configuration, thereby suppressing distortion of the magnetic flux distribution (especially sudden changes in the magnetic flux).

[0097] (4) In the resolver 1 described above, the first substrate 21 includes two layers, a first upper layer Lf1 and a first lower layer Lb1, the first portions 11f and 12f are disposed on the first upper layer Lf1, and the second portions 11b and 12b are disposed on the first lower layer Lb1. This allows the axial positional relationship (axial distance) between the two excitation coils 11 and 12 and the detection coil 13 to be equal in both the first portions 12f and 11f and the second portions 11b and 12b, and therefore the impedance difference between the two excitation coils 11 and 12 can be reduced.

[0098] (5) With regard to the radial widths of the first portions 11f, 12f and the second portions 11b, 12b that form one magnetic pole, if the radial width of the first portions 11f, 12f is set smaller than the radial width of the second portions 11b, 12b, the impedance difference between the first portions 11f, 12f and the second portions 11b, 12b that arises due to the difference in axial position of each layer Lf1, Lb1 can be suppressed.

[0099] (6) Furthermore, with regard to the number of turns of the first portions 11f, 12f and the second portions 11b, 12b that form one magnetic pole, if the number of turns of the first portions 11f, 12f is set to be less than the number of turns of the second portions 11b, 12b, the impedance difference between the first portions 11f, 12f and the second portions 11b, 12b that arises due to the difference in the axial positions of each layer Lf1, Lb1 can be suppressed.

[0100] (7) The resolver 1 described above is provided with a detection coil 13 arranged opposite the two excitation coils 11, 12. The detection coil 13 has an upper layer coil 16 arranged on the second upper layer Lf2 of the second substrate 31 and a lower layer coil 17 arranged on the second lower layer Lb2. The upper layer coil 16 and the lower layer coil 17 are formed by conductor wires Wf, Wb wound in different circumferential directions, and have outer peripheral portions 16o, 17o and inner peripheral portions 16i, 17i. When a current flows in the detection coil 13, magnetic poles of different orientations are formed between the upper layer outer peripheral portion 16o and the lower layer inner peripheral portion 17i, and between the upper layer inner peripheral portion 16i and the lower layer outer peripheral portion 17o. Furthermore, each of the outer circumferential portions 16o, 17o and inner circumferential portions 16i, 17i of the detection coil 13 is formed by a plurality of windings Wfo, Wfi, Wbo, Wbi extending in both circumferential directions from the center positions Pcs3, Pcn3 of the respective magnetic poles, and the number of windings Wfo, Wfi, Wbo, Wbi decreases with increasing distance from the center positions Pcs3, Pcn3 of the respective magnetic poles. This allows the detection coil 13 to have magnetic characteristics that form a less distorted magnetic flux distribution with peaks at the center positions Pcs3, Pcn3 of the magnetic poles for each of the south and north poles.

[0101] The resolver 1 described above is configured by combining two excitation coils 11, 12 with little distortion in the magnetic flux distribution and reduced impedance difference, and a detection coil 13 with magnetic characteristics that form a magnetic flux distribution with little distortion, so that when an AC signal is input from the signal processing circuit 4, a change in interlinkage magnetic flux (a change in induced voltage) according to the rotation angle of the rotor 3 is obtained on the detection coil 13 side. As a result, an appropriate detection signal according to the rotation angle of the rotor 3 can be obtained, thereby improving the detection accuracy of the resolver 1.

[0102] [5. Modifications] The configuration of the resolver 1 described above is an example, and is not limited to the above configuration. While the resolver 1 described above has been exemplified as having an axial multiplier angle of 1X, the resolver may also have an axial multiplier angle of kX (k is a natural number equal to or greater than 2). In other words, the "two-phase coil" described in the claims may not be a coil having an axial multiplier angle of 1X that forms one magnetic pole pair, but may be a coil having an axial multiplier angle of kX that forms k magnetic pole pairs.

[0103] 7 is a diagram showing a modified example of a configuration in which two excitation coils 11', 12' of a resolver have an axial multiplier angle of 2X, forming two magnetic pole pairs. In the following description, the same components as those described in the embodiment are given the same reference numerals, and a description of their configurations and effects will be omitted. Furthermore, components corresponding to those described in the embodiment are given a prime (') after the reference numerals of the embodiment, and detailed description will be omitted. In FIG. 7, as in FIG. 3, the sine excitation coil 11' is shown by a solid line, and the cosine excitation coil 12' is shown by a dashed line.

[0104] When the two excitation coils 11', 12' have an axial multiplier angle of 2X, the sine excitation coil 11' forms two S poles and two N poles, a total of four magnetic poles, and the cosine excitation coil 12' forms two S poles and two N poles, a total of four magnetic poles. For this reason, on the first substrate 21, four first center positions Pc1' of the sine excitation coil 11' and four second center positions Pc2' of the cosine excitation coil 12' are set, as shown in Fig. 7, and these positions Pc1', Pc2' are arranged alternately with a phase difference of 45°.

[0105] Each excitation coil 11', 12' has four first portions 11f', 12f' and four second portions 11b', 12b' as portions that form four magnetic poles. The four first portions 11f' of the sine excitation coil 11' are disposed on the first upper layer Lf1 and extend in the first circumferential direction Dc1, respectively, based on four first center positions Pc1'. The four second portions 11b' of the sine excitation coil 11' are disposed on the first lower layer Lb1 and extend in the second circumferential direction Dc2, respectively, based on four first center positions Pc1', and are stacked on the four first portions 12f' of the cosine excitation coil 12'. Each of the first portion 11f' and the second portion 11b' that form each magnetic pole of the sinusoidal excitation coil 11' has an approximately closed shape formed by winding a conductor W11' around a first central position Pc1', and is electrically connected via a single through hole 11h' provided near the first central position Pc1'.

[0106] Similarly, the four first portions 12f' of the cosine excitation coil 12' are disposed on the first upper layer Lf1 and extend in the first circumferential direction Dc1, each of which is based on one of the four second central positions Pc2'. The four second portions 12b' of the cosine excitation coil 12' are disposed on the first lower layer Lb1 and extend in the second circumferential direction Dc2, each of which is based on one of the four second central positions Pc2', and are stacked on the four first portions 11f' of the sine excitation coil 11'. The first portions 12f' and second portions 12b' that form each magnetic pole of the cosine excitation coil 12' each have a substantially closed shape formed by winding a conducting wire W12' around the second central position Pc2', and are electrically connected via a single through-hole 12h' provided in the vicinity of the second central position Pc2'.

[0107] In this way, even when the two excitation coils 11', 12' have an axial multiplier angle of 2X, the first portions 11f', 12f' and second portions 11b', 12b' that form one magnetic pole of each excitation coil 11', 12' are provided on different layers Lf1, Lb1 and extend in different circumferential directions based on the center positions Pc1', Pc2' of the magnetic pole, thereby suppressing impedance differences. Furthermore, because the second portions 11b', 12b' of each excitation coil 11', 12' are stacked on the first portions 12f', 11f' of the excitation coils 12', 11' of a different phase from the excitation coil 11', 12', an arbitrary magnetic flux distribution with little distortion (particularly, a magnetic flux distribution with few locations where magnetic coupling is lost) can be obtained. In addition, the first portions 11f', 12f' and the second portions 11b', 12b' that form one magnetic pole each have an approximately closed shape around their respective central positions Pc1', Pc2', and are electrically connected to each other via single through holes 11h', 12h', thereby suppressing the difference in wiring resistance between the two excitation coils 11', 12'.

[0108] In the configuration shown in FIG. 7, a sine wave magnetic flux distribution with two periods per circumferential revolution is formed in the sine excitation coil 11′, and a cosine wave magnetic flux distribution with two periods per circumferential revolution is formed in the cosine excitation coil 12′.

[0109] [6. Other] The first substrate 21 on which the two excitation coils 11, 12, 11', and 12' are arranged may have three or more layers stacked in the axial direction instead of a two-layer structure. In this case, one of the three or more layers may be a common layer, and both of the first portions 11f, 12f, 11f', and 12f' of the two excitation coils 11, 12, 11', and 12' may be arranged on that common layer. Furthermore, the second portions 11b, 12b, 11b', and 12b' of the two excitation coils 11, 12, 11', and 12' may be arranged on at least a layer other than the common layer, and do not have to be arranged on the same layer.

[0110] A well-known configuration of a detection coil may be applied to the detection coil provided in the resolver 1 instead of the configuration of the detection coil 13 described above. In addition, the second substrate 31 on which the detection coil is provided does not have to have a two-layer structure, but may have a single-layer structure, or may have three or more layers.

[0111] The "two-phase coils" recited in the claims may be provided on the rotor 3 instead of the stator 2. The "two-phase coils" recited in the claims are not limited to excitation coils, and may also be detection coils. The "resolver" recited in the claims may be a one-input, two-output resolver. Furthermore, the "resolver" recited in the claims may be one in which no coil is provided on the rotor (a so-called inductive sensor). In the case of this resolver, both the excitation coil and the detection coil may be provided on the stator, and a conductor may be provided on the rotor that generates a demagnetizing field in a direction that cancels out the magnetic field of the excitation coil, with a magnitude corresponding to the rotation angle. The "two-phase coils" recited in the claims may be applied as one of the excitation coil and the detection coil of such a resolver.

[0112] REFERENCE SIGNS LIST 1 resolver 2 stator 3 rotor 11, 11' sine excitation coil (two-phase coil) 11b, 11b' second portion 11f, 11f' first portion 11h, 11h' through hole 12, 12' cosine excitation coil (two-phase coil) 12b, 12b' second portion 12f, 12f' first portion 12h, 12h' through hole 13 detection coil (opposing coil) 16 upper layer coil (first coil) 16i upper layer inner circumferential portion (inner circumferential portion) 16o upper layer outer circumferential portion (outer circumferential portion) 17 lower layer coil (second coil) 17i lower layer inner circumferential portion (inner circumferential portion) 17o lower layer outer circumferential portion (outer circumferential portion) 21 first substrate 31 second substrate Dc1 first circumferential direction (first direction) Dc2 Second circumferential direction (second direction) Lb1 First lower layer (other layers excluding the common layer, lower layer) Lb2 Second lower layer (second layer) Lf1 First upper layer (common layer, upper layer) Lf2 Second upper layer (first layer) m Number of wires M Number of turns W11, W11', W12, W12' Conductor (first conducting wire) W13 Conductor (second conducting wire) Wbi Inner winding (winding) Wbo Outer winding (winding) Wfi Inner winding (winding) Wfo Outer winding (winding)

Claims

1. A resolver that detects the rotation angle of a rotor relative to a stator, comprising: a sheet-like first substrate provided on one of the stator and the rotor, having a plurality of layers stacked in the direction of the rotor's rotation axis; and sheet-like two-phase coils provided on the first substrate, each transmitting AC signals whose electrical angle phases differ from each other by 90 degrees, wherein each of the two-phase coils has, as a portion forming one magnetic pole, a first portion that extends in a first circumferential direction based on the center of the magnetic pole in a common layer of one of the plurality of layers, and a second portion that extends in a second direction opposite to the first direction based on the center of the magnetic pole in the other of the plurality of layers excluding the common layer, and is stacked on the first portion of the coil of a different phase from the first coil, wherein each of the first portion and the second portion has a substantially closed shape formed by winding a first conducting wire around the center of the magnetic pole, and are electrically connected to each other via a single through hole.

2. The resolver according to claim 1, wherein each of the first and second portions is formed by the first conducting wire routed continuously on each of the common layer and the other layer.

3. The resolver according to claim 1, wherein each of the first and second portions is wound so that the number of turns decreases as the distance from the center of the magnetic pole increases.

4. A resolver as claimed in any one of claims 1 to 3, characterized in that the plurality of layers include an upper layer as the common layer and a lower layer located further away from the other of the stator and the rotor than the upper layer, the first portion being arranged in the upper layer, and the second portion being arranged in the lower layer.

5. The resolver according to claim 4, wherein the first portion has a smaller radial width than the second portion.

6. The resolver according to claim 4, wherein the first portion has fewer turns than the second portion.

7. A rotor further comprising: a sheet-like second substrate provided on the other of the stator and the rotor; and a sheet-like opposing coil provided on the second substrate and arranged to face the two-phase coil, wherein the second substrate has a first layer and a second layer stacked in the direction of the rotation axis, the opposing coil having a substantially annular first coil formed in the first layer by a second conducting wire wound in the first direction, and a substantially annular second coil formed in the second layer by the second conducting wire wound in the second direction, each of the first coil and the second coil having an outer circumferential portion extending in the circumferential direction and an inner circumferential portion extending in the circumferential direction radially inward from the outer circumferential portion, and the opposing coil forming magnetic poles of different orientations between the outer circumferential portion of the first coil and the inner circumferential portion of the second coil, and between the inner circumferential portion of the first coil and the outer circumferential portion of the second coil, 4. The resolver according to claim 3, wherein each of the outer peripheral portion and the inner peripheral portion is formed by a plurality of windings of the second conducting wire that extend in the first direction and the second direction with reference to a center of a magnetic pole formed by each of the outer peripheral portion and the inner peripheral portion, and the number of windings decreases with increasing distance from the center of the magnetic pole.

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