Rotary transformer

Abstract

A resolver (1) is provided with a coil (13) provided on a sheet-shaped substrate (31). The coil (13) has a first coil (16) and a second coil (17) formed by winding a winding wire (W13) in different directions in the circumferential direction, respectively, in a first layer (Lf2) and a second layer (Lb2) of the substrate (31). The coil (13) forms magnetic poles with different orientations between the outer peripheral portion (16o) of the first coil (16) and the inner peripheral portion (17i) of the second coil (17) and between the inner peripheral portion (16i) of the first coil (16) and the outer peripheral portion (17o) of the second coil (17). Each of the outer peripheral portions (16o, 17o) and the inner peripheral portions (16i, 17i) is formed by a plurality of windings (Wfo, Wfi, Wbo, Wbi) of the conductive wire (W13) extending in two directions in the circumferential direction with respect to the center of each magnetic pole, and the number of the windings (Wfo, Wfi, Wbo, Wbi) is reduced as the distance from the center of the magnetic pole is greater than the distance from the center of the magnetic pole.

Description

Technical Field

[0001] The present application relates to a rotary transformer for detecting a rotation angle of a rotor relative to a stator. Background Art

[0002] In the past, for a rotary transformer that detects the rotation angle of a rotor relative to a stator, there is a known structure in which a coil having magnetic characteristics that forms a magnetic flux distribution with less distortion (no large magnetic flux change) in the circumferential direction is arranged on a sheet-like substrate. For example, Patent Document 1 discloses a rotary transformer with an axial angle of 1X in which a rotary transformer stator coil is arranged on an insulating sheet (substrate). In Patent Document 1, the rotary transformer stator coil is composed of two spiral excitation coils formed longer within a half-circle on the circumference. Each excitation coil is formed so that the pattern width of its folded-back pattern portion is wider than the pattern width of the inner circumference pattern portion and the outer circumference pattern portion. As a result, the concentration of changes in the magnetic flux near the folded-back pattern portion can be alleviated, so that the magnetic flux distribution generated by the rotary transformer stator coil can be close to a sinusoidal wave distribution.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent No. 5342963 Summary of the invention

[0006] Problems to be solved by the invention

[0007] One of the purposes of the present application is to provide a new type of rotary transformer having magnetic characteristics that form a magnetic flux distribution with less distortion in the circumferential direction. It should be noted that this purpose is not limited to the present application, and another purpose of the present application is to achieve the effects derived from the various structures shown in the specific embodiments described later and the effects that cannot be obtained by the previous technology.

[0008] Solutions to Solve Problems

[0009] The resolver of the present disclosure can be implemented as the following disclosed aspects (application examples), and can solve at least a part of the above-mentioned problems.

[0010] The rotary transformer of the present disclosure detects the rotation angle of the rotor relative to the stator, wherein the rotary transformer comprises: a sheet-shaped substrate, which is arranged on the stator or the rotor, and has a first layer and a second layer stacked in the axial direction; and a coil, which is arranged on the substrate. The coil has a first coil of a substantially annular shape formed by a wire wound in a first direction in the circumferential direction in the first layer, and a second coil of a substantially annular shape formed by the wire wound in a second direction opposite to the first direction in the second layer. The first coil and the second coil respectively have an outer peripheral portion extending in the circumferential direction, and an inner peripheral portion extending in the circumferential direction at a position radially inward of the outer peripheral portion, and the coil forms magnetic poles facing different directions between the outer peripheral portion of the first coil and the inner peripheral portion of the second coil, and between the inner peripheral portion of the first coil and the outer peripheral portion of the second coil. The outer periphery and the inner periphery are respectively formed by a plurality of windings in the conductive wire extending along the first direction and the second direction with the center of the magnetic pole formed by the outer periphery and the inner periphery as the reference, and the number of the windings decreases as the distance from the center of the magnetic pole decreases.

[0011] Effects of the Invention

[0012] According to the rotary transformer disclosed in the present invention, a first coil having a roughly annular shape formed by a conductive wire wound in a first direction in the circumferential direction in a first layer of a substrate and a second coil having a roughly annular shape formed by a conductive wire wound in a second direction opposite to the first direction in a second layer are combined, so that a coil having magnetic characteristics that form a magnetic flux distribution with less distortion in the circumferential direction can be formed, thereby providing a new type of rotary transformer. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Schematic diagram showing the structure of a resolver according to the embodiment.

[0014] Figure 2 Yes Figure 1 A top view showing the arrangement of a first substrate of a stator and a second substrate of a rotor included in a resolver.

[0015] Figure 3 Yes Figure 2 The first upper layer and the first lower layer arrangement of the stator are shown in a top view.

[0016] Figure 4 It is specified to be configured in Figure 3 A diagram showing the number of turns of the first part and the second part of each of the two excitation coils of the stator.

[0017] Figure 5 Yes Figure 2 The second upper layer and the second lower layer of the rotor are arranged in a top view shown.

[0018] Figure 6 It is specified to be configured in Figure 5 A graph showing the number of windings in the outer circumference and inner circumference of each of the upper coil and the lower coil of the rotor. DETAILED DESCRIPTION

[0019] The rotary transformer as an embodiment is described with reference to the accompanying drawings. The embodiments shown below are only examples, and are not intended to exclude various modifications and technical applications not explicitly shown in the following embodiments. The various structures of this embodiment can be modified and implemented in various ways without departing from the scope of the gist thereof.

[0020] The rotary transformer of the embodiment is a detector (sensor) that detects the rotation angle of the rotor rotating relative to the stator around the center line C. In the following description, the direction in which the center line C extends is defined as the axial direction, and the direction orthogonal to the axial direction and away from the center line C and the direction toward the center line C are defined as the radial direction. In addition, in the radial direction, the center line C side is defined as the radial inner side, and the side opposite thereto (the side away from the center line C) is defined as the radial outer side. The direction orthogonal to the axial direction and around the center line C is defined as the circumferential direction.

[0021] [1. Overall structure]

[0022] Figure 1 : is a schematic diagram showing the structure of the rotary transformer 1 of the present embodiment. The rotary transformer 1 includes a stator 2 and a rotor 3, and is a detector (sensor) for detecting the rotation angle of the rotor 3 relative to the stator 2, and is applied to, for example, a servo motor not shown in the figure. The stator 2 is a component fixed to a housing not shown in the figure of a device (such as a servo motor, a device for mounting a servo motor) to which the rotary transformer 1 is applied. The rotor 3 is a component supported by an axis so as to be able to rotate integrally with an axis not shown (around a center line C) relative to the stator 2. The rotor 3 is configured in a manner that a small gap G is separated from the stator 2 in the first axial direction Da1 in the axial direction. Hereinafter, the direction opposite to the first axial direction Da1 in the axial direction is referred to as the second axial direction Da2.

[0023] The stator 2 and the rotor 3 each include a sheet-like substrate 21, 31. Each substrate 21, 31 is a relatively thin sheet made of an insulating resin (eg, polyimide), for example, Figure 2 As shown, it is formed into a disk shape with the center line C as the center. It should be noted that Figure 2 This is a diagram showing the first substrate 21 of the stator 2 and the second substrate 31 of the rotor 3 as viewed from the gap G side between the stator 2 and the rotor 3 .

[0024] In this embodiment, if Figure 3 as well as Figure 5As shown, each substrate 21, 31 has two layers, an upper layer Lf and a lower layer Lb, which are stacked in the axial direction. Figure 3 As shown, 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 a side farther from the rotor 3 than the first upper layer Lf1 (i.e., the second axial direction Da2 side). Figure 5 As shown, the second substrate 31 provided on the rotor 3 has a second upper layer Lf2 located on the stator 2 side (ie, the second axial direction Da2 side) and a second lower layer Lb2 located farther from the stator 2 than the second upper layer Lf2 (ie, the first axial direction Da1 side).

[0025] The upper layer Lf and the lower layer Lb are provided on the surface of each substrate 21, 31 on the side of the gap G and the surface away from the gap G, respectively. Figure 3 as well as Figure 5 In FIG. 1 , the lower layer Lb is viewed through the upper layer Lf (ie, the gap G side).

[0026] It should be noted that if Figure 1 As shown, the stator 2 may be provided with an iron core 22 stacked on the second axial direction Da2 side of the first substrate 21, or a non-magnetic metal plate 23 covering the first substrate 21 and the iron core 22 from the second axial direction Da2 side. Similarly, the rotor 3 may be provided with an iron core 32 stacked on the first axial direction Da1 side of the second substrate 31, or a non-magnetic metal plate 33 covering the second substrate 31 and the iron core 32 from the first axial direction Da1 side.

[0027] like Figure 2 As shown, a plurality of coils 11 to 15 (sheet coils) are formed on the substrates 21 and 31, respectively. That is, the rotary transformer 1 is a sheet-type rotary transformer having a plurality of sheet-shaped coils 11 to 15. It should be noted that these coils 11 to 15 are made of, for example, copper foil. By using sheet coils, it is possible to achieve a thinner coil 11 to 15, thereby achieving a thinner rotary transformer 1.

[0028] In the present embodiment, a rotary transformer 1 of a two-input one-output type (two-phase excitation single-phase output type) with an axial multiple of 1X is exemplified. The rotary transformer 1 has two excitation coils 11, 12, a detection coil 13 (coil), a transmitting coil 14, and a receiving coil 15. In addition, the rotary transformer 1 is provided with a sine excitation coil 11 and a cosine excitation coil 12 as two excitation coils 11, 12, which transmit AC signals whose electrical angles are different from each other by 90 degrees. The sine excitation coil 11, the cosine excitation coil 12, and the detection coil 13 are all coils with an axial multiple of 1X, and have a magnetic characteristic of forming a magnetic pole pair (N pole and S pole) when a current flows.

[0029] like Figure 1 as well as Figure 2 As shown, the two exciting coils 11, 12 and the receiving coil 15 are disposed on the first substrate 21 and are electrically connected to the signal processing circuit 4. The detecting coil 13 and the transmitting coil 14 are disposed on the second substrate 31 and are electrically connected to each other (connected in series).

[0030] In the first substrate 21, the two excitation coils 11 and 12 are formed into, for example, an annular shape centered on the center line C, and are arranged to overlap in the axial direction. Figure 2 as well as Figure 3 When a current flows in the direction of the hollow arrow shown, two magnetic poles (a magnetic pole pair) facing in different directions are formed. In addition, the two excitation coils 11 and 12 are configured so that the centers of the respective magnetic poles are staggered and arranged at equal intervals in the circumferential direction. It should be noted that Figure 2 as well as Figure 3 In the figure, for convenience, the sine excitation coil 11 is shown by a solid line, and the cosine excitation coil 12 is shown by a dotted line.

[0031] In detail, Figure 2 As shown, the sinusoidal excitation coil 11 is configured to form a magnetic pole toward the back side of the paper (a magnetic pole marked with a cross (×) surrounded by a thinner solid line, hereinafter referred to as an "S pole") and a magnetic pole toward the front side of the paper (a magnetic pole marked with a dot (·) surrounded by a thinner solid line, hereinafter referred to as an "N pole") across the center line C when a current flows in the direction of the hollow arrow of the solid line. In the following description of the two excitation coils 11 and 12, Figure 2 as well as Figure 3 The positions of three points on the paper of the stator 2 are set as the origin (0°) of the circumferential direction of the stator 2. The sinusoidal excitation coil 11 has an S pole centered at a position of 90° (12 o'clock on the paper) and an N pole centered at a position of 270° (6 o'clock on the paper).

[0032] The cosine excitation coil 12 is configured to form an S pole (magnetic pole surrounded by a thinner dotted line and marked with an ×) and an N pole (magnetic pole surrounded by a thinner dotted line) across the center line C when a current flows in the direction of the hollow arrow of the dotted line. For example, the cosine excitation coil 12 forms an S pole centered at a position of 0° (3 o'clock on the paper), and forms an N pole centered at a position of 180° (9 o'clock on the paper).

[0033] That is, the two excitation coils 11 and 12 are configured such that the phases of the centers of the S pole of the cosine excitation coil 12, the S pole of the sine excitation coil 11, the N pole of the cosine excitation coil 12, and the N pole of the sine excitation coil 11 are sequentially shifted by 90° in the counterclockwise direction from the circumferential origin of the stator 2. It should be noted that each excitation coil 11 and 12 is actually excited by inputting an AC signal from the signal processing circuit 4, so when the rotation angle of the rotor 3 is detected, the direction (polarity) of the magnetic pole of each excitation coil 11 and 12 is not constant but changes over time. The detailed structure of the two excitation coils 11 and 12 will be described later.

[0034] In the first substrate 21 , the receiving coil 15 is formed, for example, in a shape in which a conducting wire (conductor) is arranged spirally around the center line C at a position radially inward of the two exciting coils 11 and 12 .

[0035] In the second substrate 31, the detection coil 13 is formed into a circular ring shape with the center line C as the center, and is arranged to face the two exciting coils 11 and 12. The detection coil 13 is configured to be Figure 2 as well as Figure 5 When current flows in the direction of the black arrow shown, an S pole (magnetic pole marked with ×) and an N pole (magnetic pole marked with ·) are formed as a magnetic pole pair across the center line C. It should be noted that the detection coil 13 actually generates an induced current due to the interlinkage of magnetic fluxes of the excitation coils 11 and 12, so when the rotation angle of the rotor 3 is detected, the detection coil 13 does not spontaneously form a magnetic pole.

[0036] Therefore, strictly speaking, the detection coil 13 is configured to have Figure 2 as well as Figure 5 When a current flows in the direction of the black arrow shown in FIG. 1 , the magnetic characteristics of the S pole and the N pole are formed across the center line C. In the following description of the detection coil 13, unless otherwise specified, the detection coil 13 is along the direction of the black arrow shown in FIG. Figure 2 as well as Figure 5 In the following description of the detection coil 13, the current is referred to as Figure 2 as well as Figure 5 The position of 6 o'clock on the paper of the rotor 3 shown is set as the origin (0°) in the circumferential direction of the rotor 3. The detection coil 13 forms an S pole centered at the position of 180° (12 o'clock on the paper) and an N pole centered at the position of 0° (6 o'clock on the paper).

[0037] like Figure 5As shown, the detection coil 13 has an upper coil 16 (first coil) arranged on the second upper layer Lf2 (first layer), and a lower coil 17 (second coil) arranged on the second lower layer Lb2 (second layer). The detection coil 13 is configured to form the above-mentioned magnetic pole pair through the interaction of the magnetic fluxes formed by the upper coil 16 and the lower coil 17 when current flows. It should be noted that Figure 2 In the figure, for convenience, the upper coil 16 is shown by a solid line, and the lower coil 17 is shown by a dotted line. The detailed structure of the detection coil 13 will be described later.

[0038] The transmission coil 14 and the reception coil 15 are disposed opposite to each other on the second substrate 31. The transmission coil 14 is formed in a shape in which a conductive wire is arranged spirally around the center line C, for example, at a position radially inward of the detection coil 13.

[0039] The signal processing circuit 4 is a circuit arranged at a different position from the stator 2 and the rotor 3. Figure 1 As shown, a signal generation circuit 5 and a signal detection circuit 6 are built in. 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 sent back from the receiving coil 15.

[0040] The signal generating circuit 5 inputs AC signals having electrical angles different from each other by 90 degrees to the sine excitation coil 11 and the cosine excitation coil 12. Specifically, the sine excitation coil 11 receives a cosine wave AC signal, and the cosine excitation coil 12 receives a sine wave AC signal.

[0041] In the resolver 1, when an AC signal is input from the signal processing circuit 4 to the exciting coils 11 and 12, the exciting coils 11 and 12 are excited to generate magnetic flux (see Figure 1 The magnetic flux interlinks with the detection coil 13 on the rotor 3 side to generate an induced voltage. As a result, a signal phase-modulated according to the rotation angle (relative angle) of the rotor 3 relative to the stator 2 is generated in the detection coil 13. In addition, the signal transmitted from the detection coil 13 excites the transmission coil 14 to generate a magnetic flux (see Figure 1 The magnetic flux interlinks with the receiving coil 15 on the stator 2 side to generate an induced voltage. The output waveform of the induced voltage is output to the signal processing circuit 4, and the rotation angle of the rotor 3 is obtained based on the phase change of the output waveform. That is, the resolver 1 is a modulated waveform resolver that inputs an amplitude modulated AC signal and detects the rotation angle based on a phase modulated signal generated in the detection coil 13 using the amplitude modulated AC signal.

[0042] [2. Structure of the excitation coil]

[0043] Below, refer to Figure 2~Figure 4 The structure of the two excitation coils 11 and 12 is described in detail. As described above, the two excitation coils 11 and 12 are arranged to overlap axially on the first substrate 21. As a result, each excitation coil 11 and 12 can be arranged (expanded) wider in the circumferential direction, and each excitation coil 11 and 12 can be configured to form a magnetic flux distribution with less distortion in a wider range in the circumferential direction. Therefore, the detection coil 13 can be used to obtain a detection signal (phase-modulated signal) corresponding to the rotation angle of the rotor 3, so the detection accuracy of the rotary transformer 1 is improved. It should be noted that the magnetic flux distribution with less distortion mentioned here means that in the circumferential direction, there are fewer places where the magnetic coupling between the excitation coils 11 and 12 and the detection coil 13 disappears, and there is no magnetic flux distribution with a sharp change in the magnetic flux.

[0044] Here, in the first substrate 21, the axial positions of the first upper layer Lf1 and the first lower layer Lb1 are slightly different. Therefore, as a structure in which two excitation coils 11 and 12 are stacked on the first substrate 21, for example, it is assumed that the sine excitation coil 11 is arranged in the first upper layer Lf1 and the cosine excitation coil 12 is arranged in the first lower layer Lb1. In this case, due to the slight difference in the axial positions of the layers Lf1 and Lb1, a magnetic resistance difference (impedance difference) is generated 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.

[0045] Therefore, the two excitation coils 11 and 12 are respectively provided with a structure for suppressing the impedance difference between the two excitation coils 11 and 12. Specifically, Figure 3 As shown, the two excitation coils 11 and 12 are respectively provided with first parts 11f and 12f arranged in the first upper layer Lf1 (common layer, upper layer), and second parts 11b and 12b arranged in the first lower layer Lb1 (layer other than the common layer, lower layer), and the first part 11f and the second part 11b, and the first part 12f and the second part 12b are respectively combined to form a magnetic pole. Each of the first parts 11f and 12f extends along the first circumferential direction Dc1 (for example, the clockwise direction, the first direction) of the circumferential direction with the center of the respective magnetic pole as a reference. In addition, each of the second parts 11b and 12b extends along the second circumferential direction Dc2 (for example, the counterclockwise direction, the second direction) opposite to the first circumferential direction Dc1 with the center of the respective magnetic pole as a reference, and is stacked on the first parts 12f and 11f of the excitation coils 12 and 11 of different (the other) phase from the excitation coils 11 and 12 forming the magnetic pole. As a result, the positional relationship (axial distance) between the two exciting coils 11 and 12 and the detection coil 13 in the axial direction becomes equal, and thus the impedance difference between the two exciting coils 11 and 12 can be suppressed.

[0046] In the present embodiment, each of the excitation coils 11 and 12 forms two magnetic poles, an S pole and an N pole. Therefore, each of the excitation coils 11 and 12 has two first parts 11f and 12f and two second parts 11b and 12b. The sine excitation coil 11 has an S pole first part 11fs and an S pole second part 11bs as a part forming the S pole, and has an N pole first part 11fn and an N pole second part 11bn as a part forming the N pole. The cosine excitation coil 12 has an S pole first part 12fs and an S pole second part 12bs as a part forming the S pole, and has an N pole first part 12fn and an N pole second part 12bn as a part forming the N pole.

[0047] Hereinafter, the center position of the S pole of the sine excitation coil 11 (position of 90°) is referred to as the first S pole center position Pcs1, and the center position of the N pole of the sine excitation coil 11 (position of 270°) is referred to as the first N pole center position Pcn1. In addition, the first S pole center position Pcs1 and the first N pole center position Pcn1 are also collectively referred to as the first center position Pc1. The center position of the S pole of the cosine excitation coil 12 (position of 0°) is referred to as the second S pole center position Pcs2, and the center position of the N pole of the cosine excitation coil 12 (position of 180°) is referred to as the second N pole center position Pcn2. In addition, the second S pole center position Pcs2 and the second N pole center position Pcn2 are also collectively referred to as the second center position Pc2.

[0048] As the part forming the S pole of the sine excitation coil 11, the S pole first part 11fs is, based on the first S pole center position Pcs1, in the shape of a quarter ring (partial ring) extending to the vicinity of (before) the position (0°) at which the phase difference is 90° in the first circumferential direction Dc1. The S pole second part 11bs is, based on the position Pcs1, in the shape of a quarter ring extending to the vicinity of (180°) at which the phase difference is 90° in the second circumferential direction Dc2, and is stacked on the N pole first part 12fn of the cosine excitation coil 12.

[0049] As the portion forming the N pole of the sine excitation coil 11, the N pole first portion 11fn is, based on the first N pole center position Pcn1, in the shape of a quarter circle extending to the vicinity of a position (180°) with a phase difference of 90° in the first circumferential direction Dc1, for example. The N pole second portion 11bn is, based on the position Pcn1, in the shape of a quarter circle extending to the vicinity of a position (0°) with a phase difference of 90° in the second circumferential direction Dc2, for example, and is stacked on the S pole first portion 12fs of the cosine excitation coil 12.

[0050] Similarly, as the portion forming the S pole of the cosine excitation coil 12, the S pole first portion 12fs is, for example, in the shape of a quarter-circle ring extending to the vicinity of a position (270°) with a phase difference of 90° in the first circumferential direction Dc1 based on the second S pole center position Pcs2. The S pole second portion 12bs is, for example, in the shape of a quarter-circle ring extending to the vicinity of a position (90°) with a phase difference of 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.

[0051] As the portion forming the N pole of the cosine excitation coil 12, the N pole first portion 12fn is, for example, in the shape of a quarter-circle extending to the vicinity of a position (90°) with a phase difference of 90° in the first circumferential direction Dc1 based on the second N pole center position Pcn2. The N pole second portion 12bn is, for example, in the shape of a quarter-circle extending to the vicinity of a position (270°) with a phase difference of 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.

[0052] However, in the case where the portion forming one magnetic pole as described above is composed of two parts arranged in different layers Lf1 and Lb1, it is necessary to set a portion (connection portion) that penetrates the first substrate 21 and electrically connects the portions 11f and 12f arranged in the first upper layer Lf1 and the portions 11b and 12b arranged in the first lower layer Lb1. However, at such a connection portion, the resistance value of the conductor is prone to deviation due to manufacturing conditions (for example, etching processing, plating processing). The deviation of the resistance value of such a connection portion is caused by the deviation of the wiring resistance of the excitation coils 11 and 12, and thus, a wiring resistance difference is prone to occur between the two excitation coils 11 and 12.

[0053] Therefore, the two excitation coils 11 and 12 are respectively provided with a structure for suppressing the above-mentioned wiring resistance difference. Specifically, the first part 11f, 12f and the second part 11b, 12b of each excitation coil 11 and 12 are respectively formed into a roughly closed shape formed by winding the wire W11 and W12 around the center position Pc1 and Pc2 of each magnetic pole, and the first part 11f, 12f and the second part 11b, 12b that form one magnetic pole are electrically connected via a single through hole 11h, 12h (connection part). As a result, the number of connection parts that form a magnetic pole is suppressed to a minimum, so that the wiring resistance difference caused by the deviation of the resistance value of the connection part can be suppressed. It should be noted that the wire W11 that forms each part 11f, 11b of the sine excitation coil 11 and the wire W12 that forms each part 12f, 12b of the cosine excitation coil 12 are wires of different systems and are not electrically connected to each other.

[0054] The following description will focus on the sinusoidal excitation coil 11. The first portion 11f and the second portion 11b of the sinusoidal excitation coil 11 are formed, for example, by laying out the conductive wire W11 in a manner that surrounds (or surrounds) the first center position Pc1, so that they are formed into a substantially closed shape. It should be noted that the substantially closed shape mentioned here means a shape in which the conductive wire W11 exists in all parts around the first center position Pc1 of the magnetic pole, and a shape in which the conductive wire W11 does not exist in a part around the first center position Pc1, for example, a shape in which the conductive wire W11 does not exist, for example, a shape in which the conductive wire W11 does not exist in a part around the first center position Pc1.

[0055] Each part 11f, 11b of the sinusoidal excitation coil 11 can be formed, for example, by winding a wire W11 in a spiral manner (thunder pattern) around the first center position Pc1 in each layer Lf1, Lb1 as shown in the figure. In this way, each part 11f, 11b can be formed by the wire W11 continuously laid out in each layer Lf1, Lb1 in a straight line without interruption. Each part 11f, 11b is formed in the inner area ( Figure 3 The areas indicated by dots in the figure form magnetic poles.

[0056] Furthermore, in the present embodiment, the first portion 11f and the second portion 11b are developed in such a manner that the number of turns decreases as they are farther from the first center position Pc1. That is, the conductor W11 forming each portion 11f, 11b is wound in a partially circular shape in one direction from a starting point (through hole 11h) located near the first center position Pc1 and has an end point at the outer portion of the winding, and is arranged in such a manner that the folded portion on the side opposite to the first center position Pc1 side is more sparse than the folded portion on the side of the first center position Pc1.

[0057] Thus, a magnetic flux distribution can be obtained in which the magnitude of the magnetic flux changes in a manner that the magnitude of the magnetic flux has a peak value at the first center position Pc1 and decreases as the distance from the first center position Pc1 increases, thereby suppressing the distortion of the magnetic flux distribution (particularly, a sharp change in the magnetic flux). The above description is focused on the sine excitation coil 11, but for the cosine excitation coil 12, the conductor W12 is similarly laid around the second center position Pc2 to form the first portion 12f and the second portion 12b.

[0058] The first parts 11f, 12f and the second parts 11b, 12b are respectively, for example, Figure 4 The wires W11 and W12 are arranged in a manner having a relationship of the number of turns as shown in the graph. Figure 4 is a graph that specifies the number of turns M of each portion 11f, 11b, 12f, 12b in the circumferential direction, and the horizontal axis corresponds to Figure 3The circumferential angle shown, the vertical axis corresponds to the number of turns M of each part 11f, 11b, 12f, 12b. On the vertical axis, the "(S)" side corresponds to the number of turns M of the parts 11fs, 12fs, 11bs, 12bs forming the S pole, and the "(N)" side corresponds to the number of turns M of the parts 11fn, 12fn, 11bn, 12bn forming the N pole.

[0059] It should be noted that in Figure 4 For convenience, the portions 11fs, 11fn, 12fs, and 12fn arranged in the first upper layer Lf1 are indicated by thicker lines than the portions 11bs, 11bn, 12bs, and 12bn arranged in the first lower layer Lb1. In addition, 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 dotted lines.

[0060] like Figure 4 As shown, the S-pole first portion 11fs of the sinusoidal excitation coil 11 is set so that the number of turns M increases from near 0° to near 90°, and the number of turns M is at a maximum value (here, 5) near 90°, that is, near the first S-pole center position Pcs1. The S-pole second portion 11bs of the sinusoidal excitation coil 11 is set so that the number of turns M decreases from near 90° to near 180° in a symmetrical manner with the S-pole first portion 11fs.

[0061] The N-pole first portion 11fn of the sinusoidal excitation coil 11 is set so that the number of turns M increases from about 180° to about 270°, and the number of turns M is at a maximum value (here, 5) near 270°, that is, near the first N-pole center position Pcn1. The N-pole second portion 11bn of the sinusoidal excitation coil 11 is set so that the number of turns M decreases from about 270° to about 360° in a symmetrical manner with the N-pole first portion 11fn.

[0062] In the sinusoidal excitation coil 11, the number of turns M of each part 11fs, 11bs, 11fn, 11bn is set to be approximately a sinusoidal waveform whose cycle is one circumferential cycle as mentioned above, so that when the sinusoidal excitation coil 11 is excited, a magnetic flux distribution corresponding to the change in the number of turns M of each part 11fs, 11bs, 11fn, 11bn, that is, a magnetic flux distribution in the shape of a sinusoidal wave is formed, so that a magnetic flux distribution with less distortion can be obtained.

[0063] The S-pole second portion 12bs of the cosine excitation coil 12 is set so that the number of turns M is the maximum value (here, 5) near 0°, that is, near the second S-pole center position Pcs2, and the number of turns M decreases from near 0° to near 90°. The S-pole first portion 12fs of the cosine excitation coil 12 is set so that the number of turns M decreases symmetrically with the S-pole second portion 12bs as it moves from near 0° to near -90° (270°).

[0064] The N-pole first portion 12fn of the cosine excitation coil 12 is set so that the number of turns M increases from about 90° to about 180°, and the number of turns M is at a maximum value (here, 5) near 180°, that is, near 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 about 180° to about 270° in a symmetrical manner with the N-pole first portion 12fn.

[0065] In the cosine excitation coil 12, the number of turns M of each part 12bs, 12fn, 12bn, and 12fs is set to be approximately a cosine waveform whose circumferential cycle is one cycle as described above. Therefore, when the cosine excitation coil 12 is excited, a magnetic flux distribution corresponding to the change in the number of turns M of each part 12bs, 12fn, 12bn, and 12fs, that is, a cosine wave-shaped magnetic flux distribution is formed, so that a magnetic flux distribution with less distortion can be obtained.

[0066] It should be noted that, in the present embodiment, the number of turns (maximum number of turns) of the first part 11f, 12f and the second part 11b, 12b, which respectively form one magnetic pole, is the same, but the number of turns of the first part 11f, 12f and the second part 11b, 12b may be different. For example, the number of turns of the first part 11f, 12f may be less than the number of turns of the second part 11b, 12b. Thus, the impedance difference between the first part 11f, 12f and the second part 11b, 12b caused by the difference in the axial position of each layer Lf1, Lb1 can be suppressed.

[0067] In addition, in this embodiment, if Figure 2 as well as Figure 3 As shown in the figure, the radial widths of the first part 11f, 12f and the second part 11b, 12b, which form a magnetic pole respectively, are substantially the same, but the radial widths of the first part 11f, 12f and the second part 11b, 12b may be different. For example, the area of ​​the region where the magnetic pole is formed in the first part 11f, 12f may be smaller than the area of ​​the region where the magnetic pole is formed in the second part 11b, 12b. Thus, the impedance difference between the first part 11f, 12f and the second part 11b, 12b caused by the difference in the axial position of each layer Lf1, Lb1 can be suppressed.

[0068] [3. Structure of the detection coil]

[0069] Below, refer to Figure 2 , Figure 5 , Figure 6 The structure of the detection coil 13 is described in detail. As described above, the detection coil 13 has an upper coil 16 and a lower coil 17. The magnetic fluxes of the upper coil 16 and the lower coil 17 interact with each other to form magnetic poles (S pole and N pole) facing different directions. Figure 2 as well as Figure 5 The position of the rotor 3 at 180° shown in FIG. 1 is referred to as the third S-pole center position Pcs3, and the center position of the N-pole of the detection coil 13 ( Figure 2 as well as Figure 5 The 0° position of the rotor 3 shown in the figure is called the third N-pole center position Pcn3.

[0070] like Figure 5 As shown, the detection coil 13 is formed by a wire W13 (wire) arranged in the second upper layer Lf2 and the second lower layer Lb2. It should be noted that the wire W13 forming the detection coil 13 and the wires W11 and W12 forming the excitation coils 11 and 12 are wires of different systems and are not electrically connected to the wires W11 and W12.

[0071] The upper layer coil 16 is formed into a substantially annular shape formed by winding the upper layer conductor Wf arranged in the second upper layer Lf2 (first layer) of the conductor W13 along the first circumferential direction Dc1 (first direction) with the radially outer end point as the starting point. The lower layer coil 17 is formed into a substantially annular shape formed by winding the lower layer conductor Wb arranged in the second lower layer Lb2 (second layer) of the conductor W13 along the second circumferential direction Dc2 (second direction) with the radially inner end point as the starting point. The upper layer conductor Wf and the lower layer conductor Wb are arranged in a manner of winding at least two or more times (multiple times) around the center line C without turning back in the direction opposite to the respective winding directions (the first circumferential direction Dc1 and the second circumferential direction Dc2), and are electrically connected to each other via the through hole 13h, thereby being continuously provided.

[0072] It should be noted that Figure 5 The thin arrow drawn on the wire W13 in FIG. 1 means that the end point (i.e. Figure 5 The direction of laying of the wire W13 when the upper wire Wf and the lower wire Wb are laid out in sequence (the position of the black arrow in the figure) as the starting point. The arrow of the thin line can also be said to be the direction of the current along Figure 5 The direction of flow of the current when the current flows in the direction of the black arrow.

[0073] The upper coil 16 and the lower coil 17 each have an outer peripheral portion 16o, 17o and an inner peripheral portion 16i, 17i as a portion forming two magnetic poles facing different directions. Each outer peripheral portion 16o, 17o is a portion extending in the circumferential direction near the outer peripheral edge of each of the upper coil 16 and the lower coil 17 formed in a substantially annular shape, and each inner peripheral portion 16i, 17i is a portion extending in the circumferential direction at a position radially inward of each outer peripheral portion 16o, 17o.

[0074] The upper outer peripheral portion 16o of the upper coil 16 is arranged in a manner that does not partially overlap with the upper inner peripheral portion 16i of the upper coil 16 in the circumferential direction, and is arranged at substantially the same circumferential position as the lower inner peripheral portion 17i of the lower coil 17. Similarly, the lower outer peripheral portion 17o of the lower coil 17 is arranged in a manner that does not partially overlap with the lower inner peripheral portion 17i in the circumferential direction, and is arranged at substantially the same circumferential position as the upper inner peripheral portion 16i.

[0075] In the present embodiment, the upper outer peripheral portion 16o is extended in two directions (the first circumferential direction Dc1 and the second circumferential direction Dc2) in the circumferential direction with the third N-pole center position Pcn3 as the reference in the circumferential direction except the periphery of the third S-pole center position Pcs3. The lower inner peripheral portion 17i is adjacently arranged on the radial inner side of the upper outer peripheral portion 16o. The upper inner peripheral portion 16i is extended in two directions in the circumferential direction with the third S-pole center position Pcs3 as the reference in the circumferential direction except the periphery of the third N-pole center position Pcn3. Thus, the upper outer peripheral portion 16o and the upper inner peripheral portion 16i are configured in the circumferential direction so as not to partially overlap in the peripheries of the third N-pole center position Pcn3 and the third S-pole center position Pcs3.

[0076] In this way, the upper outer peripheral portion 16o is provided on the third N-pole center position Pcn3 side, and the upper inner peripheral portion 16i is provided on the third S-pole center position Pcs3 side. Therefore, it can be said that the upper coil 16 is eccentric to the third N-pole center position Pcn3 side relative to the center line C. Figure 5 When a current flows in the direction of the black arrow shown in FIG. 1 , the upper region Rf ( Figure 5 The area shown by thick dots in the figure forms a magnetic flux of N polarity.

[0077] The same is true for the lower coil 17. The lower outer peripheral portion 17o, except for the periphery of the third N-pole center position Pcn3 in the circumferential direction, is extended in two directions in the circumferential direction with the third S-pole center position Pcs3 as a reference. The upper inner peripheral portion 16i is adjacently arranged on the radial inner side of the lower outer peripheral portion 17o. The lower inner peripheral portion 17i, except for the periphery of the third S-pole center position Pcs3 in the circumferential direction, is extended in two directions in the circumferential direction with the third N-pole center position Pcn3 as a reference. Thus, the lower outer peripheral portion 17o and the lower inner peripheral portion 17i are configured in the circumferential direction so as not to partially overlap around the third N-pole center position Pcn3 and the third S-pole center position Pcs3.

[0078] In this way, the lower layer outer peripheral portion 17o is provided on the third S pole center position Pcs3 side, and the lower layer inner peripheral portion 17i is provided on the third N pole center position Pcn3 side. Therefore, it can be said that the lower layer coil 17 is eccentric to the third S pole center position Pcs3 side relative to the center line C. The lower layer coil 17 is arranged along Figure 5 When a current flows in the direction of the black arrow shown in FIG. 1 , the lower region Rb ( Figure 5 The area shown by light dots in the figure forms a magnetic flux of S polarity.

[0079] In the detection coil 13, along Figure 2 as well as Figure 5 When current flows in the direction of the black arrow shown in FIG. 1 , the magnetic fluxes of the upper coil 16 and the lower coil 17 interact with each other. As a result, in the area radially inward of the inner circumference 16i, 17i, the magnetic flux of the upper coil 16 and the magnetic flux of the lower coil 17 cancel each other out. Figure 2 As shown in FIG. 1 , magnetic poles with different orientations are formed between the upper outer peripheral portion 16o and the lower inner peripheral portion 17i and between the upper inner peripheral portion 16i and the lower outer peripheral portion 17o. Specifically, between the upper outer peripheral portion 16o and the lower inner peripheral portion 17i, in a semicircular area ( Figure 2 The N pole is formed in the area indicated by thick dots in the figure, and between the upper inner peripheral portion 16i and the lower outer peripheral portion 17o, in the semicircular area (centered at the third S pole center position Pcs3) Figure 2 The area shown with light dots in the figure forms the S pole.

[0080] like Figure 5As shown, the upper outer peripheral portion 16o is formed by a plurality of outer windings Wfo extending in two directions in the circumferential direction based on the third N-pole center position Pcn3 in the upper conductor Wf. The upper inner peripheral portion 16i is formed by a plurality of inner windings Wfi extending in two directions in the circumferential direction based on the third S-pole center position Pcs3 in the upper conductor Wf. The plurality of windings Wfo and Wfi forming each upper outer peripheral portion 16o and the upper inner peripheral portion 16i are set so that the number of windings Wfo and Wfi is reduced as they are away from the center positions Pcn3 and Pcs3 of the respective magnetic poles.

[0081] Furthermore, in the present embodiment, a plurality of connecting wires Wfc connecting a plurality of outer windings Wfo and a plurality of inner windings Wfi are provided on the upper conductor Wf. The upper conductor Wf is arranged so that an outer winding Wfo, an inner winding Wfi, and two connecting wires Wfc connecting the ends of the windings Wfo and Wfi are formed every time the upper conductor Wf goes around the center line C.

[0082] The upper conductor Wf is arranged, for example, in the following manner: starting from a position near the third N-pole center position Pcn3 and radially outward of the position where the upper outer peripheral portion 16o is formed, an outer winding Wfo is formed toward the first circumferential direction Dc1. And arranged in the following manner: bending radially inward near the third S-pole center position Pcs3, forming a connecting wire Wfc on one side, an inner winding Wfi, and a connecting wire Wfc on the other side in sequence. In detail, the upper conductor Wf is arranged in a manner to form a connecting wire Wfc on one side toward the radial inward, and is arranged in a manner to form an inner winding Wfi toward the first circumferential direction Dc1, and then is arranged in a manner to form a connecting wire Wfc on the other side toward the radial outward. The upper conductor Wf is arranged in the periphery of the third S-pole center position Pcs3 in a manner that a part of the outer circle extending from the outer winding Wfo is cut off. It should be noted that in the present embodiment, each connecting wire Wfc is extended in the radial direction as shown in the accompanying drawings, but each connecting wire Wfc can also be extended in a direction inclined relative to the radial direction. For example, the above-mentioned one connecting wire Wfc may be arranged so as to extend radially inward and in the first circumferential direction Dc1, and the above-mentioned other connecting wire Wfc may be arranged so as to extend radially outward and in the first circumferential direction Dc1. The upper layer conductor Wf is then arranged toward the first circumferential direction Dc1 again so as to form an outer winding wire Wfo, and when passing near the third N-pole center position Pcn3, it is arranged slightly radially inward compared with the previous outer winding wire Wfo, and the above operation is repeated.

[0083] The upper conductor Wf is arranged in such a way that the circumferential width of the cutout formed by the pair of connecting wires Wfc and the inner winding wire Wfi increases every time it circles the center line C. Thus, both the upper outer peripheral portion 16o and the upper inner peripheral portion 16i are configured so that the farther away from the center positions Pcn3 and Pcs of the respective magnetic poles, the fewer the number of windings Wfo and Wfi.

[0084] It should be noted that, in the present embodiment, the phase of the circumferential position of the connecting wire Wfc of the upper conductor Wf and the circumferential position of the connecting wire Wbc of the lower conductor Wb described later is offset, so that the upper coil 16 as a whole is arranged to be inclined at a predetermined angle to the first circumferential direction Dc1 relative to the diameter line connecting the third S-pole center position Pcs3 and the third N-pole center position Pcn3. In detail, the outer winding Wfo is centered on the first offset position P1 offset by a predetermined angle to the first circumferential direction Dc1 relative to the third N-pole center position Pcn3 and extends to both sides of the circumferential direction. The inner winding Wfi is centered on the second offset position P2 offset by a predetermined angle to the first circumferential direction Dc1 relative to the third S-pole center position Pcs3 and extends to both sides of the circumferential direction. The predetermined angle can be set according to the maximum number of windings Wfo and Wfi.

[0085] The lower outer peripheral portion 17o is formed by a plurality of outer windings Wbo extending in two directions in the circumferential direction based on the third S pole center position Pcs3 in the lower conductor Wb. The lower inner peripheral portion 17i is formed by a plurality of inner windings Wbi extending in two directions in the circumferential direction based on the third N pole center position Pcn3 in the lower conductor Wb. Similar to the windings Wfo and Wfi of the upper outer peripheral portion 16o and the upper inner peripheral portion 16i, the plurality of windings Wbo and Wbi forming each lower outer peripheral portion 17o and the lower inner peripheral portion 17i are set to be less in number as they are farther away from the center positions Pcs3 and Pcn3 of the respective magnetic poles.

[0086] In this embodiment, similarly to the upper conductor Wf, the lower conductor Wb is provided with a plurality of connecting wires Wbc that connect the plurality of outer windings Wbo and the plurality of inner windings Wbi. The lower conductor Wb is arranged so that each time it goes around the center line C, an outer winding Wbo, an inner winding Wbi, and two connecting wires Wbc that connect the ends of the windings Wbo and Wbi are formed.

[0087] The lower conductor Wb is arranged, for example, in the following manner: starting from a position near the third N-pole center position Pcn3 and radially inward of the position where the lower inner peripheral portion 17i is formed (the position of the through hole 13h), an inner winding Wbi is formed toward the second circumferential direction Dc2. And arranged in the following manner: bending radially outward near the third S-pole center position Pcs3, forming a connecting wire Wbc on one side, an outer winding Wbo, and a connecting wire Wbc on the other side in sequence. In detail, the lower conductor Wb is arranged in a manner to form a connecting wire Wbc on one side toward the radial outward, and is arranged in a manner to form an outer winding Wbo toward the second circumferential direction Dc2, and then is arranged in a manner to form a connecting wire Wbc on the other side toward the radial inward. The lower conductor Wb is arranged in the vicinity of the third N-pole center position Pcn3 in such a manner that a portion of the inner circle from which the inner winding Wbi extends protrudes. It should be noted that, in the present embodiment, each connecting wire Wbc is extended in the radial direction as shown in the accompanying drawings, but each connecting wire Wbc can also be extended in a direction inclined relative to the radial direction. For example, the connecting wire Wbc of one side can also be arranged in a manner extending radially outward and in the second circumferential direction Dc2, and the connecting wire Wbc of the other side can also be arranged in a manner extending radially inward and in the second circumferential direction Dc2. The lower layer conductor Wb is then arranged toward the second circumferential direction Dc2 again in a manner of forming an inner winding wire Wbi, and when passing near the third N-pole center position Pcn3, it is arranged slightly radially outward compared to the previous inner winding wire Wbi, and the above operation is repeated.

[0088] The lower conductor Wb is arranged so that the circumferential width of the protrusion composed of a pair of connecting wires Wbc and the outer winding wire Wbo increases every time it circles the center line C. Thus, both the lower outer peripheral portion 17o and the lower inner peripheral portion 17i are configured so that the farther away from the center position Pcs3 and Pcn3 of the magnetic pole, the fewer the number of winding wires Wbo and Wbi.

[0089] It should be noted that, in the present embodiment, in contrast to the upper coil 16, the lower coil 17 as a whole is arranged to be inclined at a predetermined angle toward the second circumferential direction Dc2 relative to the diameter line connecting the third S-pole center position Pcs3 and the third N-pole center position Pcn3. In detail, the outer winding Wbo is centered on the third offset position P31 offset by a predetermined angle toward the second circumferential direction Dc2 relative to the third S-pole center position Pcs3 and extends toward both sides of the circumferential direction. In addition, the inner winding Wbi is centered on the fourth offset position P41 offset by a predetermined angle toward the second circumferential direction Dc2 relative to the third N-pole center position Pcn3 and extends toward both sides of the circumferential direction. Thus, as Figure 2As shown, the circumferential position of the connecting wire Wfc of the upper conductor Wf and the circumferential position of the connecting wire Wbc of the lower conductor Wb are arranged in phases in a manner that they are staggered in the circumferential direction. It should be noted that the above-mentioned prescribed angle of the lower coil 17 can be set according to the maximum number of windings Wbo and Wbi. The above-mentioned prescribed angle of the upper coil 16 can be the same as or different from the above-mentioned prescribed angle of the lower coil 17.

[0090] The number of windings Wfo, Wfi, Wbo, and Wbi of the outer peripheral portions 16o and 17o and the inner peripheral portions 16i and 17i in the circumferential direction is set to be, for example, Figure 6 The graph shown shows the relationship of the number of roots. Figure 6 It is a graph which defines the number m of windings Wfo, Wfi, Wbo, and Wbi of each of the portions 16o, 16i, 17o, and 17i in the circumferential direction.

[0091] exist Figure 6 In the chart of Figure 5 The circumferential angle shown. The left vertical axis corresponds to the number m of windings Wfo, Wfi, Wbo, and Wbi. On the left vertical axis, the "(S)" side corresponds to the number m of windings Wfi and Wbo forming the S pole, and the "(N)" side corresponds to the number m of windings Wfo and Wbi forming the N pole. It should be noted that Figure 6 In FIG. 1 , for convenience, the outer windings Wfo and Wbo are shown with thicker lines than the inner windings Wfi and Wbi. In addition, the windings Wfo and Wfi of the upper conductor Wf are shown with solid lines, and the windings Wbo and Wbi of the lower conductor Wb are shown with dotted lines.

[0092] In addition, Figure 6 In the graph, the right vertical axis corresponds to the number of turns M of the S pole and the N pole formed in the detection coil 13 due to the interaction of the parts 16o, 16i, 17o, and 17i. On the right vertical axis, the "(S)" side corresponds to the number of turns M of the S pole, and the "(N)" side corresponds to the number of turns M of the N pole.

[0093] like Figure 6 As shown, the inner winding wire Wfi of the upper conductor Wf and the outer winding wire Wbo of the lower conductor Wb are set so that the number m is the maximum value (here 5) near 180°, that is, near the third S pole center position Pcs3. In addition, the number m is set to decrease as the position is farther away from 180°, and the number m is the minimum value (here 0) near 0° (360°).

[0094] On the contrary, the outer winding wire Wfo of the upper layer wire Wf and the inner winding wire Wbi of the lower layer wire Wb are set so that the number m is the maximum value (here 5) near 0° (360°), that is, near the third N-pole center position Pcn3. In addition, the number m is set so that the farther away from 0°, the smaller the number m is, and the minimum value (here 0) is near 180°.

[0095] By setting the number m of windings Wfo, Wfi, Wbo, and Wbi as described above, a change in the number of turns M of a cosine wave shape forming one cycle in the circumferential direction can be obtained in the detection coil 13 as shown in the dotted waveform. Starting from the position of 90° which is the boundary position between the S pole and the N pole of the detection coil 13, in other words, a change in the number of turns of a sine wave shape forming one cycle between the S pole and the N pole can be obtained in the detection coil 13.

[0096] Thus, when 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, that is, a sine wave-shaped magnetic flux distribution is formed, so that a magnetic flux distribution with less distortion can be obtained. In other words, by setting the number m of roots of each winding Wfo, Wfi, Wbo, and Wbi in such a way that the waveform of the dotted composite wave of the lines (waveforms) of each winding Wfo, Wfi, Wbo, and Wbi is close to a sine waveform that becomes one cycle in one circumferential cycle (between the S pole and the N pole), the detection coil 13 can have a magnetic characteristic that forms a sine wave-shaped magnetic flux distribution with less distortion between the S pole and the N pole.

[0097] Here, in the present embodiment, since the connecting wires Wfc and Wbc extend in the radial direction as described above, the step positions of the waveforms showing the winding wires Wfo, Wfi, Wbo, and Wbi correspond to the positions of the connecting wires Wfc and Wbc. Figure 6 The graph of is also a graph showing the positions of the respective connecting lines Wfc and Wbc in this way, and therefore can also be said to be a graph that specifies the positional relationship of the plurality of connecting lines Wfc and Wbc in the circumferential direction.

[0098] The detection coil 13 is located at a position in the circumferential direction that passes through a sinusoidal magnetic flux distribution that forms a cycle between the S pole and the N pole, that is, Figure 6 By setting (laying out) a plurality of connecting wires Wfc and Wbc in the manner of the step positions of the waveforms of the windings Wfo, Wfi, Wbo, and Wbi shown in FIG. Figure 6 The number of turns of the waveform indicated by dots in the figure changes, thereby suppressing the distortion of the magnetic flux distribution when current flows.

[0099] It should be noted that, for the detection coil 13, the number of turns M changes at the above-mentioned step position, and the size of the magnetic flux changes according to the change in the number of turns M. Therefore, the above-mentioned step position can also be referred to as the magnetic flux change position. For the detection coil 13, even in the case where each connecting wire Wfc, Wbc is extended and arranged to be inclined relative to the radial direction, each connecting wire Wfc, Wbc is arranged in a manner to pass through the magnetic flux change position, thereby suppressing the distortion of the magnetic flux distribution when a current flows. The magnetic flux change position can be set based on the circumferential length between a pair of magnetic poles and the maximum value of the number m of each winding Wfo, Wfi, Wbo, and Wbi. In the case where each connecting wire Wfc, Wbc is extended and arranged to be inclined relative to the radial direction, each connecting wire Wfc, Wbc is preferably arranged to pass through each magnetic flux change position and make Figure 6 The step-shaped steps are arranged with an inclination like a slope. As a result, the waveform of the dotted wave that becomes the synthetic wave of the waveforms of each winding Wfo, Wfi, Wbo, and Wbi can be changed more smoothly. As a result, a waveform that is closer to a sine waveform can be obtained, so the distortion of the magnetic flux distribution (especially the rapid change of the magnetic flux) can be suppressed.

[0100] Furthermore, in the present embodiment, due to the arrangement (inclination) relationship between the upper coil 16 and the lower coil 17, the phases of the inner winding wire Wfi of the upper conductor Wf and the outer winding wire Wbo of the lower conductor Wb are shifted by the difference between the second shift position P2 and the third shift position P3. The phases of the outer winding wire Wfo of the upper conductor Wf and the inner winding wire Wbi of the lower conductor Wb are shifted by the difference between the first shift position P1 and the fourth shift position P4.

[0101] Therefore, the position (step position, magnetic flux change position) of the connecting wire Wfc of the upper conductor Wf and the position (step position, magnetic flux change position) of the connecting wire Wbc of the lower conductor Wb are arranged so as to be offset from each other by the above-mentioned phase difference. In this way, the phase of the position on the circumferential direction through which the connecting wire Wfc of the upper conductor Wf passes and the phase of the position on the circumferential direction through which the connecting wire Wbc of the lower conductor Wb passes are offset, so the step of the waveform to be dotted is finer. Therefore, a waveform closer to a sine waveform can be obtained, so that the distortion of the magnetic flux distribution (especially the rapid change of the magnetic flux) can be suppressed.

[0102] [4. Function and effect]

[0103] (1) In the above-mentioned rotary transformer 1, the detection coil 1 arranged on the second substrate 31 has an upper coil 16 arranged on the second upper layer Lf2 of the second substrate 31, and a lower coil 17 arranged on the second lower layer Lb2. The upper coil 16 and the lower coil 17 are formed by the conductive wires Wf and Wb wound in different directions in the circumferential direction. In this way, in the above-mentioned rotary transformer 1, unlike the conventional rotary transformer in which one coil (detection coil or excitation coil) is formed by two spiral coils formed within a half-circumference range in one layer, the detection coil 13 is formed by the upper coil 16 and the lower coil 17 formed by the conductive wires W13 wound in different directions in the circumferential direction in different layers Lf2 and Lb2. Thus, a novel rotary transformer 1 can be provided.

[0104] In the above-mentioned rotary transformer 1, the upper coil 16 and the lower coil 17 have outer peripheral portions 16o, 17o and inner peripheral portions 16i, 17i. When current flows in the detection coil 13, magnetic poles facing different directions are formed between the upper outer peripheral portion 16o and the lower inner peripheral portion 17i and between the upper inner peripheral portion 16i and the lower outer peripheral portion 17o. The outer peripheral portions 16o, 17o and the inner peripheral portions 16i, 17i of the detection coil 13 are respectively formed by a plurality of windings Wfo, Wfi, Wbo, and Wbi extending in two directions in the circumferential direction based on the center positions Pcs3 and Pcn3 of the respective magnetic poles, and are set so that the farther away from the center positions Pcs3 and Pcn3 of the respective magnetic poles, the fewer the number of windings Wfo, Wfi, Wbo, and Wbi. Thus, a magnetic flux distribution can be obtained in which the magnitude of the magnetic flux changes in a manner that the magnitude of the magnetic flux has a peak value at the center position Pcs3, Pcn3 of the magnetic pole and gradually decreases as the distance from the center position Pcs3, Pcn3 of the magnetic pole increases. Therefore, according to the above-mentioned resolver 1, the detection coil 13 having a structure different from that of the conventional coil can have a magnetic characteristic that forms a magnetic flux distribution with less distortion in the circumferential direction. Thus, an appropriate detection signal corresponding to the rotation angle of the rotor 3 can be obtained, so that the detection accuracy of the resolver 1 can be improved.

[0105] (2) In the above-mentioned resolver 1, the plurality of connection wires Wfc and Wbc of the upper coil 16 and the lower coil 17 are set to pass through the circumferential position (magnetic flux change position) that forms a sinusoidal magnetic flux distribution with one cycle between the S pole and the N pole. As a result, the detection coil 13 can have a magnetic characteristic that forms a sinusoidal magnetic flux distribution with less distortion between the S pole and the N pole. As a result, a more appropriate detection signal corresponding to the rotation angle of the rotor 3 can be obtained, and thus the detection accuracy of the resolver 1 can be further improved.

[0106] (3) In the above-mentioned rotary transformer 1, the phases of the circumferential positions through which the plurality of connecting wires Wfc of the upper coil 16 pass and the circumferential positions through which the plurality of connecting wires Wbc of the lower coil 17 pass are mutually offset. As a result, the magnetic flux of the detection coil 13 in the circumferential direction can be changed more finely (more step-by-step), so that the detection coil 13 can have magnetic characteristics that form a magnetic flux distribution with less distortion.

[0107] In the resolver 1 described above, the two excitation coils 11 and 12 whose magnetic flux distribution is less distorted and whose impedance difference is suppressed are combined with the detection coil 13 having magnetic characteristics that form a magnetic flux distribution with less distortion, so that when an AC signal is input from the signal processing circuit 4, a change in the linkage magnetic flux (a change in the induced voltage) corresponding to the rotation angle of the rotor 3 can be obtained on the detection coil 13 side. As a result, an appropriate detection signal corresponding to the rotation angle of the rotor 3 can be obtained, and thus the detection accuracy of the resolver 1 can be improved.

[0108] [5. Others]

[0109] The structure of the above-mentioned rotary transformer 1 is an example and is not limited to the above-mentioned structure. In the above-mentioned rotary transformer 1, a rotary transformer with an axis multiplication angle of 1X is illustrated, but the rotary transformer 1 can also be a rotary transformer with an axis multiplication angle of kX (k is a natural number greater than 2). In other words, the detection coil 13 may not be a coil with an axis multiplication angle of 1X having magnetic characteristics that form one magnetic pole pair, but a coil with an axis multiplication angle of kX having magnetic characteristics that form k magnetic pole pairs. In this case, the upper coil 16 and the lower coil 17 can have k outer peripheral portions 16o, 17o and k inner peripheral portions 16i, 17i, respectively.

[0110] Alternatively, the upper conductor Wf forming the upper coil 16 is wound in the second upper layer Lf2 along the second circumferential direction Dc2, and the lower conductor Wb forming the lower coil 17 is wound in the second lower layer Lb2 along the first circumferential direction Dc1. In addition, the first circumferential direction Dc1 and the second circumferential direction Dc2 in the above-mentioned rotary transformer 1 are only examples, and these directions may also be defined in the opposite direction. In other words, the "first coil" and "second coil" described in the technical solution may be formed by at least conductors arranged in different layers and wound in different directions in the circumferential direction.

[0111] The second substrate 31 on which the detection coil 13 is arranged may not have a double-layer structure, but may have a structure having three or more layers stacked in the axial direction. In addition, the substrate on which the detection coil 13 is arranged may not be the second substrate 31 of the rotor 3, but may be the first substrate 21 of the stator 2. The excitation coil provided in the rotary transformer 1 may also be a well-known excitation coil structure instead of the above-mentioned excitation coils 11 and 12.

[0112] The "coil" described in the technical solution is not limited to the detection coil, but may also be an excitation coil. The "rotating transformer" described in the technical solution may or may not be a two-input and one-output type rotating transformer, but may be a one-input and two-output type rotating transformer. In addition, the "rotating transformer" described in the technical solution may also be a structure in which the rotor is not provided with a coil (the so-called inductance sensor). In the case of this rotating transformer, both an excitation coil and a detection coil may be provided on the stator, and a conductor that generates a reverse magnetic field in a direction that cancels out the magnetic field of the excitation coil with a size corresponding to the rotation angle may be provided on the rotor. The "coil" described in the technical solution may also be applied as one of the excitation coil and the detection coil of such a rotating transformer.

[0113] Description of Reference Numerals

[0114] 1. Resolver

[0115] 2 Stator

[0116] 3 Rotor

[0117] 13 Detection coil (coil)

[0118] 16 Upper coil (first coil)

[0119] 16i Upper inner periphery (inner periphery)

[0120] 16o Upper periphery (periphery)

[0121] 17 Lower coil (second coil)

[0122] 17i Lower layer inner periphery (inner periphery)

[0123] 17o Lower periphery (periphery)

[0124] 31. Second substrate (substrate)

[0125] Dc1 First circumferential direction (first direction)

[0126] Dc2 Second circumferential direction (second direction)

[0127] Lb2 Second lower layer (second layer)

[0128] Lf2 Second upper layer (first layer)

[0129] m Number of roots (number of winding wires)

[0130] W13 Wire (wire)

[0131] Wbc cable

[0132] Wbi Inside Winding (winding)

[0133] Wbo Outside Winding (winding)

[0134] Wfc cable

[0135] Wfi inner winding (winding)

[0136] Wfo Outside winding (winding).

Claims

1. A rotary transformer, which detects the rotation angle of a rotor relative to a stator, characterized in that: The rotary transformer has: a sheet-like substrate, which is provided on the stator or the rotor and has a first layer and a second layer stacked in the axial direction; and a coil disposed on the substrate, The coil includes a first coil having a substantially annular shape formed by a conductive wire wound in a first direction in a circumferential direction in the first layer, and a second coil having a substantially annular shape formed by the conductive wire wound in a second direction opposite to the first direction in the second layer. The first coil and the second coil each have an outer peripheral portion extending in the circumferential direction and an inner peripheral portion extending in the circumferential direction at a position radially inward of the outer peripheral portion. The coils form magnetic poles facing different directions between the outer periphery of the first coil and the inner periphery of the second coil and between the inner periphery of the first coil and the outer periphery of the second coil. The outer periphery and the inner periphery are respectively formed by a plurality of windings in the conductive wire extending along the first direction and the second direction with the center of the magnetic pole formed by the outer periphery and the inner periphery as the reference, and the number of the windings decreases as the distance from the center of the magnetic pole decreases.

2. The rotary transformer according to claim 1, characterized in that: The first coil and the second coil are respectively provided with a plurality of connection wires for connecting the plurality of windings on the outer circumference with the plurality of windings on the inner circumference. The plurality of connecting lines are set so as to pass through positions in the circumferential direction of the sinusoidal magnetic flux distribution that forms one cycle between the magnetic poles that are oriented in different directions.

3. The rotary transformer according to claim 2, characterized in that: The positions through which the plurality of connection lines of the first coil pass and the positions through which the plurality of connection lines of the second coil pass are shifted in phase from each other.

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