Resolver stator and method for manufacturing same
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2025-04-01
- Publication Date
- 2026-08-13
Smart Images
Figure JP2025013398_13082026_PF_FP_ABST
Abstract
Description
Resolver stator and method for manufacturing the same
[0001] The present invention relates to a resolver stator and a method for manufacturing the same.
[0002] In a rotating electric machine such as a motor or a generator for driving wheels of a hybrid vehicle, an electric vehicle, etc., a resolver is used as a rotation angle sensor for detecting a rotation angle. The resolver includes a resolver stator having coils (excitation coil and output coil) disposed in slots, and a rotor facing the resolver stator through a gap. The rotation axis of a motor or the like to be detected is connected to the rotor, and an output signal corresponding to the rotation angle is obtained from the output coil based on the change in the gap permeance between the rotor and the stator accompanying the rotation of the rotor, and the rotation angle is calculated. However, the waveform of the output signal may be distorted due to the influence of noise caused by external magnetism, which may affect the detection accuracy. As a countermeasure, Patent Document 1 discloses a structure in which a plurality of air gaps are provided in the stator body of the resolver stator to block magnetic flux (external noise caused by magnetism) entering from the outer peripheral side.
[0003] However, in the configuration of Patent Document 1, there remains a possibility that external noise may enter through a path that bypasses the periphery of the plurality of air gaps and still affects the output signal. In view of this point, Patent Document 2 discloses a configuration in which the resolver stator is separated into a resolver core that supports the coils and an external attachment member disposed on the outer periphery thereof, and an air gap is provided over the entire circumference in the circumferential direction between the two. Similarly to Patent Document 2, Patent Document 3 also describes a configuration in which the resolver stator is composed of a first core portion that supports the coils and a second core portion disposed outside thereof, and an annular gap is provided between the first core portion and the second core portion.
[0004] JP-A-2006-64409 JP-A-2015-119523 JP-A-2015-104241
[0005] The configurations described in Patent Documents 2 and 3 provide a further reduction in external noise compared to the configuration in Patent Document 1. On the other hand, the opposing surface of the resolver core or the first core section facing the rotor forms a magnetic circuit with the rotor, but if its thickness (length along the lamination direction of the laminate (the axial direction of the resolver)) is too thin, the magnetic flux density will be sparse, and sufficient output sensitivity cannot be obtained. Therefore, a thickness of electromagnetic steel sheet of a predetermined value or greater is used. Furthermore, Patent Document 3 describes that the second core section is composed of a laminate of electromagnetic steel sheets similar to that of the first core section. Although there is no specific description regarding the thickness, both the first and second core sections have a multilayer structure, and referring to the drawings, it is assumed that the thickness of both is the same. In the case of the structure in Patent Document 2, there is a description that the external mounting member can be made from a non-magnetic material, but there is also a description of an embodiment in which it is made from a magnetic material. As an example, it is described that the same magnetic material as the resolver core is used, and referring to the drawings, although there is no specific description regarding the thickness of both, it is assumed that the thickness of both is the same.
[0006] As described above, the resolver's rotor is connected to the rotating shaft of the motor or other device being detected, and the resolver stator is fixed via clamps or flanges so as to face the end face of the motor's stator. Therefore, the closer the resolver stator is to the motor's stator, the more likely it is that leakage magnetic flux from the motor will flow into the resolver, resulting in the aforementioned external noise.
[0007] The present invention has been made in view of the above, and aims to provide a resolver stator and a method for manufacturing the same that can further reduce external noise in a configuration in which the magnetic circuit section (corresponding to the "resolver core" in Patent Document 2 and the "first core section" in Patent Document 3) and the external mounting member (corresponding to the "external mounting member" in Patent Document 2 and the "second core section" in Patent Document 3) are separate in order to reduce external noise.
[0008] To solve the above problems, the present invention provides a resolver stator having: an annular magnetic circuit portion having slots and teeth supporting coils alternately arranged in the circumferential direction on the inner peripheral edge facing the rotor; an annular external mounting member having an inner diameter larger than the outer diameter of the magnetic circuit portion and an inner peripheral edge disposed with a gap between it and the outer peripheral edge of the magnetic circuit portion; and a resin portion integrating the magnetic circuit portion and the external mounting member, wherein the external mounting member is made of a magnetic steel plate, its thickness in the axial direction is less than the thickness of the magnetic circuit portion in the axial direction, and the back surface of the external mounting member and the back surface of the magnetic circuit portion are located on the same plane perpendicular to the axial direction, and the axial distance from the rotating electric machine to be detected to the surface of the magnetic steel plate constituting the external mounting member located on the rotating electric machine side is longer than the axial distance from the magnetic circuit portion to the surface located on the rotating electric machine side.
[0009] It is preferable that the magnetic steel plate constituting the external mounting member is made from a single sheet. The magnetic circuit portion can be made from a laminate of multiple electromagnetic steel plates stacked along the axial direction, a sintered soft magnetic material, or an electromagnetic steel plate having a predetermined width, with its width direction aligned with the axial direction and the width direction corresponding to the thickness direction along the axial direction.
[0010] Furthermore, it is preferable that the external mounting member has multiple gaps formed through it in the thickness direction, arranged symmetrically along the circumference, to suppress the inflow of external magnetic flux that would cause noise. It is also preferable that the inner periphery of the external mounting member has an inner periphery wall portion that rises in the thickness direction.
[0011] The magnetic circuit portion may be formed in a substantially U-shape in plan view and comprises a connecting plate portion along the circumferential direction and two tooth pieces projecting inward from each end of the connecting plate portion, and a plurality of divided cores that form an annular shape in plan view by arranging multiple tooth pieces back to back in the circumferential direction, and a tooth piece of one divided core that is adjacent back to back with the tooth piece of the other divided core combines to form one tooth, and the gap surrounded by the connecting plate portion and the two tooth pieces of the divided core may constitute the slot.
[0012] In this case, it is preferable that the divided core has a recess formed on its outer edge, and the resin portion is provided by penetrating the recess. Furthermore, it is preferable that the outer surfaces of each corner of the connecting plate portion and the two tooth pieces of the divided core are chamfered, and that a gap is formed between the chamfered outer surfaces of the chamfered corners of adjacent back-to-back tooth pieces, allowing the resin portion to penetrate. The magnetic circuit portion can also be configured using an annular core that is pre-formed in an annular shape in plan view, with a notch formed on the outer edge of the annular core, and the resin portion being provided by penetrating the notch.
[0013] Furthermore, the present invention provides a method for manufacturing a resolver stator having an annular magnetic circuit portion having slots and teeth for supporting coils alternately arranged in the circumferential direction on the inner peripheral edge facing the rotor, and an annular external mounting member having an inner diameter larger than the outer diameter of the magnetic circuit portion and an inner peripheral edge disposed with a gap between it and the outer peripheral edge of the magnetic circuit portion, wherein the external mounting member is made of a magnetic steel plate and its thickness in the axial direction is less than the thickness of the magnetic circuit portion in the axial direction, and the method includes the steps of positioning the magnetic steel plate constituting the external mounting member in a mold, arranging the magnetic circuit portion together with the coil inside the magnetic steel plate, and then injecting resin to form a resin portion and integrating the magnetic circuit portion and the external mounting member, wherein the mold used has a support surface formed such that when the external mounting member and the magnetic circuit portion are arranged, the back surface of the magnetic steel plate of the external mounting member and the back surface of the magnetic circuit portion are on the same plane perpendicular to the axial direction.
[0014] When arranging the magnetic circuit portion together with the coil inside the magnetic steel plate, it is preferable to insert the positioning holes formed in the thickness direction of the magnetic circuit portion through the positioning pins provided in the mold, and then inject the resin to form the resin portion.
[0015] The magnetic circuit portion is formed in a substantially U-shape in plan view and comprises a connecting plate portion along the circumferential direction and two tooth pieces projecting inward from each end of the connecting plate portion. Multiple tooth pieces are arranged back-to-back in the circumferential direction, thereby forming an annular shape in plan view. The divided core has a recess formed on its outer edge. When the resin is injected, the resin enters the recess of the divided core and becomes part of the resin portion. A combination of a tooth piece from one back-to-back adjacent divided core and a tooth piece from the other divided core constitutes one tooth, and the void surrounded by the connecting plate portion of the divided core and the two tooth pieces projecting inward from each end is preferably the slot.
[0016] The magnetic circuit portion is formed in a substantially U-shape in plan view and comprises a connecting plate portion along the circumferential direction and two tooth pieces projecting inward from each end of the connecting plate portion. Multiple divided cores are arranged back-to-back in the circumferential direction, forming an annular shape in plan view. The outer surfaces of each corner of the divided core, where the connecting plate portion and the two tooth pieces meet, are chamfered, and a gap is formed between the chamfered outer surfaces of the chamfered corners of adjacent back-to-back tooth pieces, into which the resin portion enters. When the resin is injected, the resin enters the gap and becomes part of the resin portion. Preferably, a combination of a tooth piece from one back-to-back adjacent divided core and a tooth piece from the other divided core constitutes one tooth, and the void surrounded by the connecting plate portion of the divided core and the two tooth pieces projecting inward from each end is the slot. Furthermore, it is also preferable to use a magnetic circuit portion that is constructed using an annular core that is pre-formed as an annular shape in plan view, and in which a notch is formed on the outer edge of the annular core, and to manufacture it so that when the resin is injected, the resin enters the notch of the annular core and becomes part of the resin portion.
[0017] The resolver stator of the present invention has an external mounting member that is thinner than the magnetic circuit section, and the back surfaces of the external mounting member and the magnetic circuit section are located on the same plane perpendicular to the axial direction. The rotating electric machine to be detected and the axial distance from the surface of the magnetic steel plate constituting the external mounting member that is on the rotating electric machine side are positioned further apart than the axial distance from the surface of the magnetic circuit section that is on the rotating electric machine side. As a result, compared to the case where the external mounting member is formed with the same thickness as the magnetic circuit section, the distance from the rotating electric machine to be detected can be increased, suppressing the inflow of external magnetic flux that causes noise, i.e., leakage magnetic flux from the rotating electric machine, and improving the accuracy of rotation angle detection.
[0018] Furthermore, according to the method for manufacturing a resolver stator of the present invention, a mold is used which, when the external mounting member and the magnetic circuit section are arranged, has a support surface formed such that the back surface of the magnetic steel plate of the external mounting member and the back surface of the magnetic circuit section are on the same plane perpendicular to the axial direction. As a result, the axial distance between the rotating electric machine to be detected and the surface of the magnetic steel plate constituting the external mounting member that is located on the rotating electric machine side is greater than the axial distance between the surface of the magnetic circuit section that is located on the rotating electric machine side, thereby increasing the effect of suppressing the intrusion of external noise in the resulting resolver stator.
[0019] Figure 1(a) is a perspective view showing a resolver stator according to one embodiment of the present invention, Figure 1(b) is a perspective view showing the magnetic circuit section and the external mounting member combined, and Figure 1(c) is an exploded perspective view of the resolver stator shown in Figure 1(a). Figure 2(a) is a plan view to explain the state in which the gap between the external mounting member and the magnetic circuit section is formed almost uniformly in the circumferential direction when a combination of divided cores is used, Figure 2(b) is a plan view to explain the state in which the gap between the external mounting member and the magnetic circuit section is formed almost uniformly in the circumferential direction when a magnetic circuit section made of an annular electromagnetic steel plate is used, Figure 2(c) is a plan view showing a state in which the gap is uneven with the same configuration as in Figure 2(a), and Figure 2(d) is a plan view showing a state in which the gap is uneven with the same configuration as in Figure 2(b). Figure 3(a) is a perspective view illustrating a structure in which a resin part is provided in a magnetic circuit section using a segmented core with irregularities on its outer edge, and Figure 3(b) is a cross-sectional view taken along line A-A in Figure 3(a). Figure 4 is a schematic diagram illustrating the separation distance between the motor-side member, which is a rotating electric machine, and the resolver stator according to the above embodiment. Figures 5(a) and (b) show examples of air gaps. Figure 6(a) is a diagram illustrating a method for manufacturing a resolver stator according to one embodiment of the present invention, showing the magnetic circuit section and external mounting member arranged in the lower mold, and Figure 6(b) is a partially enlarged view of Figure 6(a). Figures 7(a) and (b) are diagrams illustrating positioning holes provided in the magnetic circuit section. Figure 8 shows the analysis results of Experimental Example 1. Figure 9(a) shows the magnetic flux density distribution of Experimental Example 2, Figure 9(b) shows the magnetic flux density distribution of Comparative Example 2, and Figure 9(c) shows the measurement results of disturbance error representing the effect of noise on the structures of Experimental Example 2 and Comparative Example 2. Figure 10(a) compares the positional accuracy (core positional accuracy) of the magnetic circuit section of Experimental Example 3 and Comparative Example 3, and Figure 10(b) shows the results of the analysis of the effect of noise on the structures of Experimental Example 3 and Comparative Example 3. Figure 11 shows a part of an embodiment using a long electromagnetic steel sheet bent into a roughly U-shape. Figure 12 is a diagram for explaining an external mounting member equipped with an inner peripheral wall.Figure 13(a) is a perspective view illustrating a structure in which a resin portion is provided in a magnetic circuit section using a segmented core that does not have irregularities on its outer edge, and Figure 13(b) is a cross-sectional view taken along line B-B in Figure 13(a). Figure 14(a) is a plan view of an embodiment equipped with a segmented core with chamfered corners, Figure 14(b) is an enlarged view of section A in Figure 14(a), and Figure 14(c) is a cross-sectional view illustrating the state in which the resin portion has penetrated into the gap formed between the chamfered outer surfaces. Figure 15(a) is a plan view of an embodiment equipped with an annular core with a notch formed on its outer edge, and Figure 15(b) is a cross-sectional view taken along line B-B in Figure 15(a) with the resin portion provided.
[0020] Embodiments of the present invention will be described below with reference to the drawings. Figures 1(a) to 1(c) show the overall configuration of the resolver stator 1 according to this embodiment, and consist of a magnetic circuit section 10, an external mounting member 20, and a resin section 30. A rotor 2, which is connected to the rotating shaft of a rotating electric machine such as a motor, is arranged on the inner circumference side of the magnetic circuit section 10.
[0021] The magnetic circuit section 10 is formed in an annular shape in plan view, and a plurality of slots 11 are provided along the circumferential direction of the inner peripheral edge 10a. Teeth 12 are provided between adjacent slots 11, 11. That is, the slots 11 and teeth 12 are provided alternately in the circumferential direction. Furthermore, as shown in Figures 1(c) and 2(a), the magnetic circuit section 10 of this embodiment is formed in a substantially U-shape in plan view and is constructed by combining a plurality of divided cores 10b, each having a connecting plate section 10b1 along the circumferential direction and two tooth pieces 10b2, 10b3 projecting inward from each end of the connecting plate section 10b1 along the circumferential direction. One tooth 12 is formed when one tooth piece 10b2 of one circumferentially adjacent divided core 10b and the other tooth piece 10b3 of the other divided core 10b are combined back to back. The gap surrounded by the connecting plate portion 10b1 and the two tooth pieces 10b2 and 10b3 of the divided core 10b constitutes the slot 11.
[0022] The magnetic circuit section 10 is composed of a laminate of electromagnetic steel sheets. The electromagnetic steel sheets are made of high permeability materials that generate the magnetic flux or magnetic flux density necessary for detecting the rotation angle of the rotor when a magnetic field is applied, and are formed from non-oriented electromagnetic steel sheets, grain-oriented electromagnetic steel sheets, non-oriented silicon steel sheets, grain-oriented silicon steel sheets, stainless steel, structural carbon steel, soft magnetic alloys such as Fe-Ni alloy, Permendur such as Fe-Al alloy and Fe-Co alloy, amorphous metals, and ferrites such as FeO, CoO, and ZnO. In this embodiment, the magnetic circuit section 10 is composed of a collection of multiple divided cores 10b, so each divided core 10b is composed of a laminate of divided electromagnetic steel sheets 15a (see Figure 14(c)).
[0023] The magnetic circuit section 10 may, of course, be composed of a laminate of a single annular electromagnetic steel sheet 15b (annular core 10h (see Figure 15)) that has been pre-formed into an annular shape, rather than being composed of an assembly of divided cores 10b as in this embodiment, as shown in Figure 2(b). The divided electromagnetic steel sheets 15a or annular electromagnetic steel sheet 15b are usually, for example, 0.25 to 0.5 mm thick, and are laminated in the range of 8 to 32 sheets using means such as crimping or bonding, so that the thickness of the laminated divided core 10b or annular core 10h along the lamination direction (axial direction of the resolver stator 1) is in the range of 4 to 7 mm.
[0024] A coil 13 is wound around and supported on each tooth 12. Therefore, the coil 13 is positioned in the space of two adjacent slots 11, 11 in the circumferential direction, flanking the wound tooth 12. The coil 13 comprises an excitation coil and an output coil. In the case of one-phase excitation and two-phase output, the output coil consists of a sine winding and a cosine winding. In the case of two-phase excitation and one-phase output, the excitation coil consists of a sine winding and a cosine winding. Electrical wiring is connected to the coil 13 via a connector. When an AC voltage is applied to the excitation coil, a transformed output voltage corresponding to the rotation angle of the rotor 2 is output from the output coil, and this signal is input to a calculation unit such as an R / D converter to determine the rotation angle.
[0025] As shown in Figures 1(a) to (c) and 2(a) and (b), the external mounting member 20 is formed in an annular shape in plan view, with an inner diameter larger than the outer diameter of the magnetic circuit section 10. Therefore, when the external mounting member 20 is placed outside the magnetic circuit section 10, a gap 21 is formed between the inner peripheral edge 20a of the external mounting member 20 and the outer peripheral edge 10c of the magnetic circuit section 10 (see Figures 2(a) and (b)).
[0026] The external mounting member 20 is formed from a magnetic steel sheet. If it is formed from synthetic resin, durability may be a concern, so it is preferable to form it from a magnetic steel sheet. As the magnetic steel sheet, cold-rolled steel sheet, galvanized steel sheet, some stainless steels, etc., can be used. The thickness of the external mounting member 20 in the axial direction is less than the thickness of the magnetic circuit section 10 in the axial direction (in this embodiment, since it is formed from a laminate of electromagnetic steel sheets 15a and 15b, this is the total thickness in the laminate direction). The external mounting member 20 can also be made from a laminate of magnetic steel sheets, but in the case of magnetic steel sheets such as cold-rolled steel sheets, if the thickness is 1 mm or more, it has the desired strength, so it is preferable to form it from a single sheet for ease of manufacture, manufacturing cost, etc. The thickness is preferably in the range of 1 / 4 to 1 / 2 of the thickness of the magnetic circuit section 10.
[0027] When the resolver stator 1 is fixed to the end face of the stator of a rotating electric machine whose rotation angle is to be detected, the surfaces of the magnetic circuit section 10 and the external mounting member 20 facing the rotating electric machine are designated as front surfaces 10d and 20d, and the surfaces facing the opposite side are designated as back surfaces 10e and 20e. In this case, as shown in Figure 3(b), the back surface 10e of the magnetic circuit section 10 and the back surface 20e of the external mounting member 20 are positioned on the same plane perpendicular to the axial direction of the resolver stator 1, that is, they are arranged flush with the gap 21 between them.
[0028] As a result, as shown in Figure 4, the axial distance A1 from the rotating electric machine to be detected (e.g., a motor) to the surface 20d of the magnetic steel plate which is the external mounting member 20 becomes longer than the axial distance A2 to the surface 10d of the magnetic circuit section 10. If the axial thickness of the external mounting member 20 and the axial thickness of the magnetic circuit section 10 are the same as in the conventional case (external mounting member 20' shown by dashed lines in Figure 4), the above relationship of distances would be A1' = A2. However, in this embodiment, A1 > A2, so the inflow of leakage magnetic flux from the rotating electric machine that causes noise can be suppressed.
[0029] Furthermore, even if the external mounting member 20 is thinner than the magnetic circuit section 10 used in this embodiment, if the back surface 20e of the magnetic steel plate constituting the external mounting member 20 is not on the same plane as the back surface 10e of the magnetic circuit section 10, then inevitably the back surface 20e of the magnetic steel plate will be closer to the rotating electric machine than the back surface 10e of the magnetic circuit section 10. In other words, compared to this embodiment, the axial distance A1 to the surface 20d of the magnetic steel plate which is the external mounting member 20 will be shorter.
[0030] In this embodiment, the external mounting member 20 is positioned such that the axial distance A1 to the surface 20d of the magnetic steel plate is as short as possible compared to the axial distance A2 to the surface 10d of the magnetic circuit section 10. This arrangement effectively suppresses the inflow of leakage magnetic flux from the rotating electric machine.
[0031] The influence of leakage flux from a rotating electric machine, more specifically as shown in Figure 4, involves, using a motor as an example of a rotating electric machine, the distance B between the motor-side rotor core and the magnet, the distance C between the motor-side rotor core and the air gap between the motor-side rotor core and the motor-side stator core, and the distance D to the motor-side coil (shortest distance). As described above, since the resolver is installed by fixing the resolver stator 1 to the motor-side stator core, the distance B between the motor-side rotor core and the magnet is approximately the same as the axial distance A1 to the surface 20d of the magnetic steel plate, which is the external mounting member 20. The distance C between the motor-side rotor core and the air gap between the motor-side stator core is slightly oblique, but is close to the axial distance A1 to the surface 20d of the magnetic steel plate, which is the external mounting member 20.
[0032] Therefore, the distance B between the motor-side rotor core and the magnet, and the distance C between the motor-side rotor core and the motor-side stator core, are such that the axial distance A1 to the surface 20d of the magnetic steel plate which is the external mounting member 20 is longer than the axial distance A1' (= A2) if the thickness of the external mounting member 20 were the same as the thickness of the magnetic circuit section 10, thereby reducing the influence of leakage magnetic flux from those locations.
[0033] On the other hand, the distance D to the motor-side coil core is small because the motor-side coil protrudes in the axial direction, and the distance to the external mounting member 20 is close to the direction perpendicular to the axial direction. However, both the magnetic circuit section 10 and the external mounting member 20 are located outside the end of the motor-side coil in the axial direction. Therefore, the distance A1 in the axial direction to the surface 20d of the magnetic steel plate which is the external mounting member 20 is longer than the distance A1' (= A2) in the axial direction if the thickness of the external mounting member 20 were the same as the thickness of the magnetic circuit section 10. Consequently, the distance D to the motor-side coil is also longer than the distance D' to the external mounting member 20 if it were the same thickness as the magnetic circuit section 10.
[0034] Therefore, of the three distances B, C, and D, at least the distances B and C along a straight line parallel or nearly parallel to the axial distance A1 to the surface 20d of the magnetic steel plate which is the external mounting member 20 are significantly longer compared to the case where the external mounting member 20 is the same thickness as the magnetic circuit section 10, thus reducing the influence of leakage flux from the motor. In addition, the distance D from the motor-side coil is also slightly longer compared to the case where the external mounting member 20 is the same thickness as the magnetic circuit section 10, contributing to the suppression of leakage flux from the motor.
[0035] The external mounting member 20 is provided with multiple circumferential gaps 22 formed through the thickness direction to suppress the inflow of external magnetic flux (mainly leakage magnetic flux from the motor) that would otherwise cause noise. As shown in Figure 1, in this embodiment, the gaps 22 consist only of arc-shaped elongated holes 22a, but this is not limited to this. For example, as shown in Figure 5(a), they can be configured as a combination of elongated holes 22a and circular holes 22b, or as shown in Figure 5(b), they can be configured as a combination of elongated holes 22a and notches 22c cut out in a semicircular shape from the outer edge of the external mounting member 20. At least a portion of these gaps 22 (elongated holes 22a, circular holes 22b, notches 22c) are used as mounting holes through which bolts or the like are inserted when attaching to the external member.
[0036] It is preferable that the voids 22 (elongated holes 22a, round holes 22b, and notches 22c) are arranged point-symmetrically. In Figure 1, it is preferable that the elongated holes 22a are arranged point-symmetrically; in Figure 5(a), it is preferable that the elongated holes 22a and round holes 22b are each arranged point-symmetrically; and in Figure 5(b), it is preferable that the elongated holes 22a and notches 22c are each arranged point-symmetrically. By arranging them point-symmetrically, an even number of elongated holes 22a, round holes 22b, and notches 22c are each formed at equal intervals in the circumferential direction.
[0037] By arranging the gaps 22 (elongated holes 22a, round holes 22b, notches 22c) in a point-symmetrical manner, the magnetic flux distribution becomes more even compared to the case where an odd number of gaps 22 (elongated holes 22a, round holes 22b, notches 22c) are arranged circumferentially and are not point-symmetrically, as shown in Experimental Example 2 below. As a result, the influence of external noise can be reduced.
[0038] In addition, as in Patent Document 1, when the parts corresponding to the magnetic circuit section 10 and the external mounting member 20 in this embodiment are formed from a single laminate of electromagnetic steel sheets, it is necessary to perform roll stacking. As a result, when the teeth and slots of the magnetic circuit section are aligned, the voids provided in the external mounting member do not align in the lamination direction, causing misalignment. However, in this embodiment, since the external mounting member 20 is made from a separate material from the magnetic circuit section 10, misalignment does not occur even if the external mounting member 20 is made from a laminate of multiple magnetic steel sheets. In particular, in this embodiment, since it is made from a single magnetic steel sheet, there is no such concern at all, and it is easy to provide the voids 22 (elongated holes 22a, round holes 22b, notches 22c) point-symmetrically.
[0039] As described above, a gap 21 is formed between the inner peripheral edge 20a of the external mounting member 20 and the outer peripheral edge 10c of the magnetic circuit portion 10. This gap 21 is provided to suppress the inflow of leakage magnetic flux from the outside, but as shown in Figures 2(c) and (d), if the width of the gap 21 is uneven and there are narrow parts, leakage magnetic flux will easily flow in from those narrow parts. Therefore, it is preferable that the width of the gap 21 be as uniform as possible in the circumferential direction, as shown in Figures 2(a) and (b). In order to make the width of the gap 21 as uniform as possible in the circumferential direction, it is preferable to position the magnetic circuit portion 10 in the mold when molding the resin portion 30, but this point will be described later.
[0040] Reference numeral 23 in Figures 1(a) and 3(a) indicates a terminal block equipped with terminals 23a for electrically connecting to the coil 13 and an external power supply, and is supported by utilizing one of the voids 22 (elongated holes 22a in this embodiment) formed in the external mounting member 20.
[0041] As shown in Figures 3(a) and 3(b), the resin part 30 is formed in an annular shape on both sides near the boundary between the magnetic circuit part 10 and the external mounting member 20 so as to cover the outer peripheral edge 10c and the portion of the outer peripheral edge 10c of the surface 10d and back surface 10e of the magnetic circuit part 10, and the portion of the inner peripheral edge 20a of the surface 20d and back surface 20e of the external mounting member 20. The resin part 30 integrates the two while providing electrical insulation between them. Preferably, the resin part 30 is provided so as to fit into the gap 21 between the outer peripheral edge 10c of the magnetic circuit part 10 and the inner peripheral edge 20a of the external mounting member 20. In addition, the resin part 30 covers the magnetic circuit part 10 and the external mounting member 20 in an annular shape as described above, and also covers a portion of the surface of the terminal block 23 supported in one of the elongated holes 22a of the external mounting member 20, thereby fixing the terminal block 23 to the external mounting member 20.
[0042] The resolver stator 1 of this embodiment is manufactured as follows. First, the external mounting member 20 is placed inside the mold. Specifically, as shown in Figure 6(a), the lower mold 100 is provided with an outer circumference positioning projection 101 that matches the outer diameter of the external mounting member 20, and the external mounting member 20 is placed in line with the outer circumference positioning projection 101.
[0043] Further, as shown in FIGS. 1(b) and 1(c), the magnetic circuit unit 10 used in this embodiment has positioning holes 10f formed in the thickness direction. The magnetic circuit unit 10 is composed of a laminate of electromagnetic steel sheets 15a and 15b, and the electromagnetic steel sheets 15a and 15b are integrated in the stacking direction by caulking or adhesion. Therefore, the positioning hole 10f may be a hole penetrating from the back surface 10e side to the front surface 10d side of the magnetic circuit unit 10 as shown in FIG. 7(a), or may be a hole drilled to an appropriate depth from the back surface 10e side toward the front surface 10d side as shown in FIG. 7(b). As shown in FIG. 1, when the magnetic circuit unit 10 is formed from the split cores 10b, it is preferable that the positioning holes 10f are provided for each split core 10b. The formation position of the positioning hole 10f in the split core 10b may be at the portion of the teeth 12 or outside the slot 11, and is not limited. In the case of being composed of a laminate of the annular electromagnetic steel sheets 15b (see FIG. 2(b)), it is preferable that a plurality of them are formed at predetermined intervals in the circumferential direction.
[0044] In the lower mold 100, as shown in FIGS. 6(a) and 6(b), positioning pins 102 to be inserted into the positioning holes 10f are provided at positions corresponding to the above-described positioning holes 10f formed in the magnetic circuit unit 10 inside the external attachment member 20. When the magnetic circuit unit 10 is arranged on the lower mold 100, the positioning pins 102 are inserted into the positioning holes 10f (see FIGS. 7(a) and 7(b)). Here, the outer peripheral positioning convex portion 101 and the positioning pins 102 for positioning the outer peripheral portion of the external attachment member 20 are provided such that when the external attachment member 20 and the magnetic circuit unit 10 are positioned by these, the gap 21 between them is formed with a width that is as uniform as possible in the circumferential direction.
[0045] In addition, in order to further improve the positioning accuracy of the magnetic circuit unit 10, as shown in FIGS. 6(a), (b) and FIGS. 7(a), (b), as the lower mold 100, inside the position where the positioning pins 102 are provided, it is preferable to use a lower mold 100 in which teeth positioning convex portions 103 for the teeth 12 are provided at predetermined intervals in the circumferential direction, and the ends of the respective protruding pieces 12a extending along the inner peripheral edge of the teeth 12 of the magnetic circuit unit 10 abut thereon.
[0046] Further, as shown in FIG. 6(b), on the bottom surface of the lower mold 100, when the back surface 10e of the magnetic circuit unit 10 and the back surface 20e of the external attachment member 20 are arranged, a flat support surface 104 is provided to position the respective back surfaces 10e, 20e on the same plane orthogonal to the axial direction.
[0047] After setting the magnetic circuit unit 10 and the external attachment member 20 on the lower mold 100 as described above, an upper mold (not shown) having a predetermined inner surface shape is covered. Then, when resin is injected, a resin portion 30 is formed in a predetermined shape on the front surface 10d, 20d sides and the back surface 10e, 20e sides of the magnetic circuit unit 10 and the external attachment member 20 (see FIG. 3(b)). As a result, although the magnetic circuit unit 10 and the external attachment member 20 have different thicknesses, their back surfaces 10e, 2e are arranged on the same plane orthogonal to the axial direction.
[0048] (Experimental Example 1) (Comparison of the thickness of the external attachment member) As the magnetic circuit unit 10, eight electromagnetic steel sheets 15 with a thickness of 0.5 mm were laminated to have an overall thickness of 4 mm along the axial direction. The external attachment member 20 used a resolver stator 1 (Experimental Example 1) having the configuration of the present embodiment with a single magnetic steel sheet (cold-rolled steel sheet) with a thickness of 2 mm, and a resolver stator (Comparative Example 1) using a single magnetic steel sheet (cold-rolled steel sheet) with a thickness of 4 mm, which is the same as the thickness of the magnetic circuit unit, and having the same configuration as Experimental Example 1 except for this, an analysis was performed to obtain the detection error of the rotation angle when leakage magnetic flux, which becomes noise, flows in as disturbance error.
[0049] FIG. 8 shows the results. From the analysis results, it can be seen that Experimental Example 1 can reduce the disturbance error by about 40% compared with Comparative Example 1.
[0050] (Experimental Example 2) (Differences due to the arrangement of the gaps) The noise effect was analyzed for a resolver stator 1 (Experimental Example 2, Figure 9(a)) having the configuration of this embodiment in which eight elongated holes 22a and notches 22c are formed at equal intervals in the circumferential direction on an external mounting member 20 made of a single magnetic steel plate, and both the elongated holes 22a and notches 22c are arranged point-symmetrically, and for a configuration (Comparative Example 2, Figure 9(b)) in which seven elongated holes 22a and notches 22c are formed at equal intervals in the circumferential direction on an external mounting member 20 made of a single magnetic steel plate, and the elongated holes 22a and notches 22c are not arranged point-symmetrically. In both cases, the number of coils is 14.
[0051] Figure 9(a) shows the magnetic flux density distribution for Experimental Example 2, and Figure 9(b) shows the magnetic flux distribution for Comparative Example 2. The circled areas in each figure indicate areas that are 180 degrees opposite each other. Comparing the magnetic flux densities at these areas, it can be observed that the magnetic flux density distribution is symmetrical in the configuration of Experimental Example 2 in Figure 9(a), whereas in the configuration of Comparative Example 2 in Figure 9(b), the magnetic flux density distribution is biased and not symmetrical.
[0052] Figure 9(c) shows the analysis results comparing the detection error of the rotation angle as a disturbance error when leakage flux, which acts as noise, flows into Experimental Example 2 in Figure 9(a) and Comparative Example 2 in Figure 9(b). It can be seen that Experimental Example 2 can reduce the disturbance error significantly more than Comparative Example 2.
[0053] (Experimental Example 3) (Difference in the presence or absence of a manufacturing process using positioning pins for the magnetic circuit section) When injection molding the resin section 30, the positional accuracy (whether or not there is a bias) of the magnetic circuit section 10 with respect to the external mounting member 20 was compared between a resolver stator 1 (Experimental Example 3) manufactured using a lower mold 100 equipped with positioning pins 102, which is the method of this embodiment, and a resolver stator (Comparative Example 3) manufactured using a lower mold 100 that does not have positioning pins 102, but is equipped only with outer peripheral positioning protrusions 101 and tooth positioning protrusions 103.
[0054] As shown in Figure 10(a), Experimental Example 3 showed a 39% improvement in the positional accuracy of the magnetic circuit section 10 compared to Comparative Example 3. Therefore, it is preferable that the gap 21 between the inner peripheral edge 20a of the external mounting member 20 and the outer peripheral edge 10c of the magnetic circuit section 10 has a uniform width in the circumferential direction, but the accuracy can be improved by using the positioning pin 102 for positioning.
[0055] When the effect of noise was measured for multiple samples in Experimental Example 3 and Comparative Example 3, as shown in Figure 10(b), the effect of noise was reduced in Experimental Example 3 compared to Comparative Example 3. Furthermore, when comparing the sample-to-sample variability of SIN-induced voltage and COS-induced voltage for Experimental Example 3 and Comparative Example 3, the variability was smaller in Experimental Example 3 than in Comparative Example 3.
[0056] From the experimental results above, it can be seen that the configuration of the external mounting member 20 according to this embodiment is effective in reducing the influence of external noise. In addition, it can be seen that the influence of noise can be further reduced by combining this with at least one of the following: forming the gap portion 22 point-symmetrically as in this embodiment, or using the positioning pin 102 to position the magnetic circuit portion 10 during injection molding of the resin portion 30.
[0057] For example, by adopting one of the following configurations, the noise effect can be reduced compared to the conventional configuration: a configuration having only structure X in which the external mounting member 20 is thinner than the magnetic circuit portion 10, and the back surface 10e of the magnetic circuit portion 10 and the back surface 20e of the external mounting member 20 are located on the same plane perpendicular to the axial direction of the resolver stator 1; a configuration having both structure X and structure Y in which the gap portion 22 of the external mounting member 20 is formed point-symmetrically, but positioning is not performed using the positioning pin 102 of the magnetic circuit portion 10 during injection molding of the resin portion 30; a configuration having both structure X and structure Z in which positioning is performed using the positioning pin 102 of the magnetic circuit portion 10, but the gap portion 22 of the external mounting member 20 is not point-symmetrical but is formed in an odd number of places, for example, in the circumferential direction; or a configuration having all of structures X, Y, and Z. However, from the standpoint of further reducing the effects of noise, a configuration having both structure X and Y, or both structure X and Z, is preferable to a configuration having only structure X, and a configuration having all of structures X, Y, and Z is even more preferable.
[0058] In the above embodiment, the magnetic circuit section 10 is made up of a laminate of multiple electromagnetic steel sheets 15a and 15b. However, it can also be made up of other materials used as the magnetic circuit section (core) of a motor, such as a sintered soft magnetic material (Fe-based, Fe-P-based, Fe-Si-based, etc.) having a predetermined thickness along the axial direction.
[0059] Furthermore, in the magnetic circuit section 10 of the above embodiment, the electromagnetic steel sheets 15a and 15b are stacked in the direction of thickness along the axial direction of the resolver stator 1, which is the stacking direction of the resolver stator 1. The width direction of the elongated electromagnetic steel sheet bent into a substantially U shape, as disclosed in Japanese Patent Application Publication No. 2011-239645 by the present applicant, is aligned with the width direction of the elongated electromagnetic steel sheet, which is folded into a substantially U shape, and an electromagnetic steel sheet 15c of a predetermined width is used, with the substantially U-shaped open end facing inward to connect the coils (see Figure 11). In this case, the width direction W is greater than the thickness of the external mounting member 20, and one end face W1 in the width direction is integrated with the resin part 30 such that it is located on the same plane as the back surface 20e of the external mounting member 20, which is perpendicular to the axial direction of the resolver stator 1.
[0060] Furthermore, the external mounting member 20 can be configured not simply as an annular shape, but as shown in Figure 12, with an inner circumferential wall portion 24 that rises in the thickness direction, which is the axial direction of the resolver stator 1, on its inner edge. Since the external mounting member 20 is made of a single sheet of magnetic steel, such an inner circumferential wall portion 24 can also be easily formed by drawing. By providing such an inner circumferential wall portion 24 with a gap 21 between it and the magnetic circuit portion 10, the effect of blocking further magnetic flux inflow of noise from the outside is enhanced.
[0061] In the embodiments shown in Figures 1 and 3, as shown in those figures, the outer peripheral edge 10c of the divided core 10b constituting the magnetic circuit portion 10 is provided with irregularities. However, as shown in Figure 13, it is also possible to have a configuration in which the outer peripheral edge 10c does not have irregularities. However, when forming the resin portion 30 that integrates the magnetic circuit portion 10 and the external mounting member 20, in the embodiment of Figure 3, the resin penetrates into the recesses of the outer peripheral edge 10c and exerts an anchoring effect. Therefore, if the resin is molded to surround the recesses, the magnetic circuit portion 10 can be fixed with less resin (see Figure 3(b)). In contrast, in the embodiment of Figure 13, it is necessary to mold the resin portion to surround the protrusions shown in Figure 3(a). Therefore, in order to reduce the diameter of the resin portion 30 and make it more compact, it is preferable to have an configuration in which the outer peripheral edge 10c of the magnetic circuit portion 10 is provided with irregularities, as shown in Figures 1 and 3.
[0062] Furthermore, as shown in Figures 14(a) to (c), it is also preferable that the divided core 10b be configured such that the outer surfaces 10b4 and 10b5 of the corners of the connecting plate portion 10b1 and each tooth portion 10b2 and 10b3 are chamfered. While it is possible to use an R-shaped chamfer, a C-shaped chamfer is more preferable. As shown in Figure 14(b), among adjacent divided cores 10b, 10b, a roughly triangular gap 10b6 is formed in plan view between the outer surface 10b4 of the corner on the side of one tooth portion 10b2 and the outer surface 10b5 of the corner on the side of the other tooth portion 10b3. As a result, as shown in Figure 14(c), the injected resin penetrates into the gap 10b6, exhibiting an anchoring effect, which allows the magnetic circuit portion 10 and the external mounting member 20 to be fixed more securely.
[0063] The means for inserting and fixing the resin part 30 into the recess and the gap 10b6 can be either the recess or the gap 10b6, and of course it is also possible to have a configuration that includes both a recess and a gap 10b6, for example, as the divided core 10b used in experimental example 2 in Figure 9(a).
[0064] Furthermore, when the magnetic circuit section 10 is composed of an annular core 10h that is pre-formed in an annular shape, it is preferable to form at least one notch 10h1 on the outer edge of the annular core 10h, as shown in Figure 15(a). As shown in Figure 15(b), by injecting the resin section 30 into this notch 10h1, the fixing to the external mounting member 20 when using the annular core 10h as the magnetic circuit section 10 can be made more secure, similar to the above.
[0065] 1 Resolver stator 10 Magnetic circuit section 10a Inner edge (of the magnetic circuit section) 10b Divided core 10c Outer edge (of the magnetic circuit section) 10d Surface (of the magnetic circuit section) 10e Back surface (of the magnetic circuit section) 10f Positioning hole 10h Annular core 11 Slot 12 Teeth 15a Electromagnetic steel sheet (electromagnetic steel sheet for the divided core) 15b Electromagnetic steel sheet (annular electromagnetic steel sheet) 20 External mounting member 20a Inner edge 20d Surface (of the external mounting member) 20e Back surface (of the external mounting member) 21 Gap 22 Void 22a Elongated hole 22b Round hole 22c Notch 23 Terminal block 24 Inner wall section 30 Resin section 100 Lower mold 101 Outer positioning projection 102 Positioning pin 103 Positioning protrusion for teeth
Claims
1. A resolver stator having an annular magnetic circuit section having slots and teeth supporting coils alternately arranged in the circumferential direction on the inner peripheral edge facing the rotor; an annular external mounting member having an inner diameter larger than the outer diameter of the magnetic circuit section and an inner peripheral edge positioned with a gap between it and the outer peripheral edge of the magnetic circuit section; and a resin section integrating the magnetic circuit section and the external mounting member, wherein the external mounting member is made of a magnetic steel plate, its thickness in the axial direction is less than the thickness of the magnetic circuit section in the axial direction, and the back surface of the external mounting member and the back surface of the magnetic circuit section are located on the same plane perpendicular to the axial direction, and the axial distance from the rotating electric machine to be detected to the surface of the magnetic steel plate constituting the external mounting member located on the rotating electric machine side is longer than the axial distance from the magnetic circuit section to the surface located on the rotating electric machine side.
2. The resolver stator according to claim 1, wherein the magnetic steel plate constituting the external mounting member is made from a single plate.
3. The resolver stator according to claim 1, wherein the magnetic circuit portion is composed of a laminate of a plurality of electromagnetic steel sheets stacked along the axial direction, a sintered soft magnetic material, or an electromagnetic steel sheet having a predetermined width, with its width direction aligned with the axial direction and the width direction corresponding to the thickness direction along the axial direction.
4. The resolver stator according to claim 1, wherein the external mounting member is provided with a plurality of gaps formed through the thickness direction, arranged point-symmetrically along the circumferential direction, for suppressing the inflow of external magnetic flux that would cause noise.
5. The resolver stator according to claim 1, wherein the inner peripheral edge of the external mounting member is provided with an inner peripheral wall portion that rises in the thickness direction thereof.
6. The resolver stator according to claim 4, wherein the magnetic circuit portion is formed in a substantially U-shape in plan view and comprises a connecting plate portion along the circumferential direction and two tooth pieces projecting inward from each end of the connecting plate portion, and is constructed using a plurality of divided cores that form an annular shape in plan view by arranging a plurality of tooth pieces back to back adjacent to each other in the circumferential direction, and a tooth piece of one divided core and a tooth piece of the other divided core that are adjacent back to back combine to form one tooth, and the gap surrounded by the connecting plate portion and the two tooth pieces of the divided core constitutes the slot.
7. The resolver stator according to claim 6, wherein the divided core has a recess formed on its outer edge, and the resin portion is provided by penetrating the recess.
8. The resolver stator according to claim 6 or 7, wherein the outer surfaces of each corner of the divided core between the connecting plate portion and the two tooth pieces are chamfered, and a gap is formed between the chamfered outer surfaces of the chamfered corners of adjacent back-to-back tooth pieces for the resin portion to enter.
9. The resolver stator according to claim 4, wherein the magnetic circuit portion is configured using an annular core that is pre-formed in an annular shape in plan view, a notch is formed on the outer edge of the annular core, and the resin portion is provided by penetrating the notch.
10. A method for manufacturing a resolver stator, comprising: an annular magnetic circuit portion having slots and teeth for supporting coils alternately arranged in the circumferential direction on its inner peripheral edge facing the rotor; and an annular external mounting member having an inner diameter larger than the outer diameter of the magnetic circuit portion, with its inner peripheral edge positioned on the outer peripheral edge of the magnetic circuit portion with a gap between them, wherein the external mounting member is made of a magnetic steel plate, and its thickness in the axial direction is less than the thickness of the magnetic circuit portion in the axial direction; the method for manufacturing a resolver stator includes the steps of positioning the magnetic steel plate constituting the external mounting member in a mold, arranging the magnetic circuit portion together with the coil inside the magnetic steel plate, and then injecting resin to form a resin portion to integrate the magnetic circuit portion and the external mounting member, wherein the mold used has a support surface formed such that, when the external mounting member and the magnetic circuit portion are arranged, the back surface of the magnetic steel plate of the external mounting member and the back surface of the magnetic circuit portion are on the same plane perpendicular to the axial direction.
11. The method for manufacturing a resolver stator according to claim 10, wherein when arranging the magnetic circuit portion together with the coil inside the magnetic steel plate, the positioning hole formed in the thickness direction of the magnetic circuit portion is inserted through a positioning pin provided in the mold, and then the resin portion is injected to form the resin portion.
12. The method for manufacturing a resolver stator according to claim 11, wherein the magnetic circuit portion comprises a connecting plate portion formed in a substantially U-shape in plan view and oriented in the circumferential direction, and two tooth pieces projecting inward from each end of the connecting plate portion, and a plurality of divided cores are used to form an annular shape in plan view by arranging multiple tooth pieces back to back adjacent to each other in the circumferential direction, wherein the divided core has a recess formed on its outer edge, and when the resin is injected, the resin enters the recess of the divided core and becomes part of the resin portion, and a combination of a tooth piece of one back-to-back adjacent divided core and a tooth piece of the other divided core constitutes one tooth, and the void surrounded by the connecting plate portion of the divided core and the two tooth pieces projecting inward from each end is the slot.
13. The method for manufacturing a resolver stator according to claim 11, wherein the magnetic circuit portion comprises a connecting plate portion formed in a substantially U-shape in plan view and oriented in the circumferential direction, and two tooth pieces projecting inward from each end of the connecting plate portion, and a plurality of divided cores are arranged in the circumferential direction with the tooth pieces facing each other back to back, thereby forming an annular shape in plan view, wherein the outer surfaces of each corner of the divided core between the connecting plate portion and the two tooth pieces are chamfered, and a gap is formed between the chamfered outer surfaces of the chamfered corners of adjacent back-to-back tooth pieces into which the resin portion enters, wherein when the resin is injected, the resin enters the gap and becomes part of the resin portion, and the combination of a tooth piece of one back-to-back adjacent divided core and a tooth piece of the other divided core constitutes one tooth, and the void surrounded by the connecting plate portion of the divided core and the two tooth pieces projecting inward from each end is the slot.
14. The method for manufacturing a resolver stator according to claim 11, wherein the magnetic circuit portion is configured using an annular core that is pre-formed in an annular shape in a plan view, and a notch is formed on the outer edge of the annular core, and when the resin is injected, the resin enters the notch of the annular core and becomes part of the resin portion.