Rotary electric machine

Abstract

This rotary electric machine (1) has a shaft (2), a rotor (4), a stator (3), a bearing (6), a housing (5), and a resolver (8). The resolver (8) has: a resolver rotor (82) that is disposed between the bearing (6) and the rotor (4) in the axial direction (Y) and rotates together with the shaft (2); and a resolver stator (81) that is disposed with a gap (G2) between the resolver stator (81) and the resolver rotor (82). Between the resolver stator (81) and the rotor (4) in the axial direction (Y), are provided: a magnetic shield (9) formed in an annular shape around the shaft (2); and a low magnetic permeability part (7) that is provided so as to be sandwiched between the resolver stator (81) and the magnetic shield (9) in the axial direction (Y) and that is formed of a material having a magnetic permeability that is smaller than the magnetic permeability of the magnetic shield (9).

Description

Rotating electric machines

[0001] The present disclosure relates to a rotating electric machine.

[0002] A conventional rotating electric machine has been disclosed that has a resolver, which is a magnetic sensor, to detect the rotational position of the rotating electric machine. The resolver is composed of a resolver rotor, a resolver stator core, and a resolver coil wound around the resolver stator core, and detects the rotational position of the rotor using magnetism. Therefore, when the resolver is close to the stator and rotor of the rotating electric machine, magnetic flux generated from the stator and rotor of the rotating electric machine flows into the resolver, reducing the angle detection accuracy of the resolver for the rotational angle of the rotor of the rotating electric machine (hereinafter, "the angle detection accuracy of the resolver for the rotational angle of the rotor of the rotating electric machine" will be referred to as "the angle detection accuracy of the resolver").

[0003] As a configuration in which a resolver is disposed close to the stator and rotor of a rotating electric machine, a configuration has been disclosed in which the resolver is disposed within a housing constituting the rotating electric machine, and the resolver is disposed between a bearing that holds the rotor shaft and a rotor core of the rotating electric machine.As a means for preventing magnetic flux generated from the stator and rotor of the rotating electric machine from flowing into the resolver, a configuration has been disclosed in which a magnetic shield made of a magnetic material is disposed between the resolver stator and the rotor of the rotating electric machine, and the resolver stator is fixed by sandwiching it between the housing of the rotating electric machine and the magnetic shield (see, for example, Patent Document 1).

[0004] JP 2009-50056 A

[0005] In conventional rotating electric machines, the resolver stator is fixed to the housing, so that the resolver stator comes into contact with a magnetic shield made of a magnetic material. As a result, magnetic flux generated from the stator and rotor of the rotating electric machine flows into the magnetic shield, and the magnetic flux flows from the magnetic shield into the resolver, resulting in a problem of reduced angle detection accuracy of the resolver.

[0006] The present disclosure discloses a technology for solving the above-mentioned problems, and aims to provide a rotating electric machine that can suppress the flow of magnetic flux generated from the stator and rotor of the rotating electric machine into the resolver and the resulting decrease in the angle detection accuracy of the resolver, thereby improving the angle detection accuracy of the resolver.

[0007] a resolver stator disposed axially between the rotor and the bearing; a resolver rotor disposed axially between the rotor and the bearing; a resolver rotor disposed radially between the rotor and the bearing; a resolver stator disposed radially between the resolver rotor and the bearing; a resolver rotor disposed radially between the resolver rotor and the bearing; a resolver stator disposed radially opposite the resolver rotor and the gap; a resolver stator having a resolver stator core back portion and a ring-shaped resolver stator core back portion; and a resolver stator core having a plurality of resolver teeth protruding from the radially inner side of the resolver stator core back portion and spaced apart in the circumferential direction; and a plurality of resolver coils wound around each of the resolver teeth. A magnetic shield formed in an annular shape around the shaft is provided between the resolver stator and the rotor in the axial direction, and a low magnetic permeability portion is provided sandwiched between the resolver stator and the magnetic shield in the axial direction and made of a material having a magnetic permeability lower than that of the magnetic shield.

[0008] According to the rotating electric machine of the present disclosure, it is possible to suppress the flow of magnetic flux generated from the stator and rotor of the rotating electric machine into the resolver and the resulting decrease in the angle detection accuracy of the resolver, thereby improving the angle detection accuracy of the resolver.

[0009] 1 is an axial cross-sectional view showing the configuration of a rotating electric machine according to a first embodiment. FIG. 2 is a plan view showing the configuration of a resolver stator of the rotating electric machine shown in FIG. 1. FIG. 3 is a plan view showing the configuration of a low magnetic permeability portion as viewed from the rotor side of the rotating electric machine shown in FIG. 1. FIG. 4 is a plan view showing the configuration of a magnetic shield as viewed from the rotor side of the rotating electric machine shown in FIG. 1. FIG. 5 is a plan view showing a configuration in which a resolver stator, a low magnetic permeability portion, and a magnetic shield are superimposed as viewed from the rotor side of the rotating electric machine shown in FIG. 1. FIG. 6 is a plan view showing a configuration in which a resolver stator, a low magnetic permeability portion, and a magnetic shield are fixed as viewed from the rotor side of the rotating electric machine shown in FIG. 1. FIG. 7 is a cross-sectional view showing an enlarged portion of the rotating electric machine shown in FIG. 1. FIG. 8 is an axial cross-sectional view showing the configuration of another rotating electric machine according to the first embodiment. FIG. 9 is an axial cross-sectional view showing the configuration of a rotating electric machine according to a second embodiment. FIG. 10 is a plan view showing the configuration of a low magnetic permeability portion as viewed from the rotor side of the rotating electric machine shown in FIG. 9. FIG. 11 is a plan view showing a configuration in which a resolver stator, a low magnetic permeability portion, and a magnetic shield are superimposed as viewed from the rotor side of the rotating electric machine shown in FIG. 9. FIG. 12 is an axial cross-sectional view showing a partial configuration of a rotating electric machine according to a third embodiment. 14 is a plan view showing a configuration in which a resolver stator, a low magnetic permeability portion, and a magnetic shield are superimposed as seen from the rotor side of the rotating electric machine shown in Fig. 12. FIG. 15 is an axial cross-sectional view showing the configuration of a rotating electric machine according to embodiment 4. FIG. 16 is a plan view showing the configuration of a magnetic shield as seen from the resolver side of the rotating electric machine shown in Fig. 14.

[0010] In the following description, each direction in the rotating electric machine 1 will be indicated as an axial direction Y, a circumferential direction Z, a radial direction X, an outer side X1 of the radial direction X, and an inner side X2 of the radial direction X of the central axis Q of the shaft 2 which is the center of rotation of the rotor 4. Therefore, each direction in the stator 3 and other parts will be described based on these directions.

[0011] Embodiment 1. Fig. 1 is an axial cross-sectional view showing the configuration of a rotating electric machine according to embodiment 1. Fig. 2 is a plan view showing the configuration of a resolver stator of the rotating electric machine shown in Fig. 1. Fig. 3 is a plan view showing the configuration of a low magnetic permeability portion as viewed from the rotor side of the rotating electric machine shown in Fig. 1. Fig. 4 is a plan view showing the configuration of a magnetic shield as viewed from the rotor side of the rotating electric machine shown in Fig. 1.

[0012] Fig. 5 is a plan view showing a configuration in which a resolver stator, a low magnetic permeability portion, and a magnetic shield are superimposed, as seen from the rotor side of the rotating electric machine shown in Fig. 1. Fig. 6 is a plan view showing a configuration in which a resolver stator, a low magnetic permeability portion, and a magnetic shield are fixed, as seen from the rotor side of the rotating electric machine shown in Fig. 1. Fig. 7 is a cross-sectional view showing an enlarged portion of the rotating electric machine shown in Fig. 1. Fig. 8 is an axial cross-sectional view showing the configuration of another rotating electric machine according to embodiment 1.

[0013] As shown in Fig. 1, the rotating electric machine 1 has a shaft 2, a stator 3, a rotor 4, a housing 5, a bearing 6, and a resolver 8. Although the shaft 2 is shown in Fig. 1 as an example made of a solid material, the present invention is not limited to this and the shaft 2 may be similarly configured as, for example, a hollow shaft 2 provided with an oil passage in the axial direction Y, or a shaft 2 having a boss structure in which a member of the shaft 2 provided along the central axis Q is connected to a cylindrical core holding portion and rotates integrally.

[0014] The rotor 4 is mounted on the shaft 2 and rotates together with the shaft 2. The rotor 4 has a cylindrical rotor core 41 and a permanent magnet 42 inserted into the rotor core 41. The rotor 4 rotates about the central axis Q via the shaft 2 due to an attractive force generated by the magnetic flux generated by the stator 3 and the magnetic flux generated by the rotor 4. The stator 3 is disposed opposite the rotor 4 on the outer side X1 in the radial direction X, with a gap G1 (see FIG. 7 ) interposed therebetween. The stator 3 has a cylindrical stator core 31 and a coil 32 wound around the stator core 31. The stator 3 is housed in the housing 5 by being press-fitted or fixed with bolts or the like (not shown).

[0015] The resolver 8 detects the rotation angle of the rotor 4. The resolver 8 is installed between the bearing 6 and the rotor 4 in the axial direction Y. The resolver 8 has a resolver stator 81 and a resolver rotor 82. The resolver rotor 82 is installed on the outer periphery of the shaft 2 and rotates together with the shaft 2. The resolver stator 81 is arranged opposite the resolver rotor 82 on the outer side X1 in the radial direction X, with a gap G2 (see FIG. 7 ) interposed therebetween. The resolver stator 81 has a resolver stator core 811 and a resolver coil 812.

[0016] 2, the resolver stator core 811 has an annular resolver stator core back portion 801 and a plurality of resolver teeth portions 802 that protrude from an inner side X2 in the radial direction X of the resolver stator core back portion 801 and are formed at intervals in the circumferential direction Z. The resolver coils 812 are formed by being wound around the resolver teeth portions 802, respectively. The resolver coils 812 are used for input / output signals of the resolver 8. The housing 5 is formed with an annular protrusion 51 that protrudes toward the rotor 4 and into which the outer periphery of the resolver stator 81 is fitted and fixed. By inserting and fixing the resolver stator 81 into the inner side X2 in the radial direction X of the protrusion 51, the central axis Q of the rotary electric machine 1 and the central axis Q of the resolver stator 81 are precisely coaxial and are restricted in the radial direction X.

[0017] A magnetic shield 9, which is a magnetic body formed in an annular shape around the shaft 2, is disposed between the resolver stator 81 and the rotor 4 in the axial direction Y. The magnetic shield 9 is formed of, for example, an iron-based material. A low-permeability portion 7, which is formed of a material having a lower magnetic permeability than the magnetic shield 9, is disposed between the resolver stator 81 and the magnetic shield 9 in the axial direction Y and is sandwiched between the resolver stator 81 and the magnetic shield 9. As shown in FIGS. 3 and 4 , the outer shape of the magnetic shield 9 and the outer shape of the low-permeability portion 7 are configured in an annular shape.

[0018] By forming the magnetic shield 9 and the low permeability portion 7 in this manner, the magnetic shield 9 can prevent the magnetic flux generated from the stator 3 and the magnetic flux generated from the rotor 4 from flowing into the resolver 8, thereby improving the angle detection accuracy of the resolver 8. Furthermore, since the low permeability portion 7 is disposed between the resolver stator 81 and the magnetic shield 9 in the axial direction Y, a constant distance is maintained between the magnetic shield 9 and the resolver 8, and magnetic flux does not easily pass through the low permeability portion 7. Therefore, the magnetic flux generated from the stator 3 and the rotor 4 and flowing in the magnetic shield 9 can be prevented from flowing into the resolver 8, thereby further improving the angle detection accuracy of the resolver 8.

[0019] As shown in Fig. 2, the resolver stator 81 has a plurality of elongated fixing holes 80 formed in the circumferential direction Z and penetrating in the axial direction Y in a resolver stator core back portion 801 located on the outer side X1 in the radial direction X of the resolver coil 812. As shown in Fig. 3, the low permeability portion 7 has a plurality of fixing holes 70 formed in the circumferential direction Z and penetrating in the axial direction Y. As shown in Fig. 4, the magnetic shield 9 has a plurality of fixing holes 90 formed in the circumferential direction Z and penetrating in the axial direction Y.

[0020] The fixing holes 80, 70, 90 of the resolver stator 81, the low magnetic permeability portion 7, and the magnetic shield 9 are formed at the same locations in the circumferential direction Z and the radial direction X. When the resolver stator 81, the low magnetic permeability portion 7, and the magnetic shield 9 are stacked at predetermined positions in the axial direction Y and the circumferential direction Z, as shown in FIG. 5, the fixing holes 80, 70, 90 are configured to communicate in the axial direction Y.

[0021] As shown in Fig. 2, a plurality of positioning recesses 800 are formed in the circumferential direction Z on the outer periphery of the resolver stator 81, recessed toward the inner side X2 in the radial direction X. As shown in Fig. 3, the low permeability portion 7 is formed with positioning holes 700 for positioning at positions different from the fixing holes 70. As shown in Fig. 4, the magnetic shield 9 is formed with positioning holes 900 for positioning at positions different from the fixing holes 90.

[0022] As shown in FIG. 1 , a positioning pin 500 is formed on the housing 5. A recess 800 of the resolver stator 81 is inserted into the positioning pin 500 to regulate the position of the resolver 8 in the circumferential direction Z. Then, a positioning hole 700 of the low-permeability portion 7 and a positioning hole 900 of the magnetic shield 9 are inserted into the positioning pin 500 to position the low-permeability portion 7 and the magnetic shield 9. Then, the positioned resolver stator 81, low-permeability portion 7, and magnetic shield 9 are fixed to the housing 5 by a bolt 100 as a common fixing portion, which is installed in the fixing holes 80, 70, and 90 of each member (see FIGS. 6 and 7 ). As shown in FIG. 7 , the bolt 100 does not contact the inner wall of the fixing hole 80 of the resolver stator 81, and a predetermined space S is provided in the radial direction X between the bolt 100 and the inner wall of the fixing hole 80.

[0023] By installing the bolt 100 in this manner, the resolver stator 81, the low magnetic permeability portion 7, and the magnetic shield 9 can be fixed at one time with the common bolt 100, thereby improving the productivity of the rotating electric machine 1 and reducing the production cost of the rotating electric machine 1. Furthermore, if the bolt 100 is made of a magnetic material, by providing a predetermined space S between the resolver stator 81 and the bolt 100 in the radial direction X, it is possible to prevent magnetic flux generated from the stator 3 and the rotor 4 from flowing from the bolt 100 to the resolver stator 81, and to prevent deterioration of the angle detection accuracy of the resolver 8. Alternatively, it is also possible to form the bolt 100 from a non-magnetic material.

[0024] In this embodiment, as described above, the resolver stator 81, the low magnetic permeability portion 7, and the magnetic shield 9 are fixed to the housing 5 using the fixing holes 80, 70, and 90 formed at common positions in each member and the common bolt 100, which is a more preferable example in terms of the productivity and production cost of the rotating electric machine 1 and the space efficiency near the fixing portions. However, the present invention is not limited to this. For example, the resolver stator 81, the low magnetic permeability portion 7, and the magnetic shield 9 can be fixed to the housing 5 by overlapping them with a flange of the housing 5 and using a clamp portion that can clamp the periphery as a common fixing portion. In this case, it is possible to improve the angle detection accuracy of the resolver 8, and it is also effective in that the respective members can be fixed at once, improving the productivity of the rotating electric machine 1 and reducing the production cost of the rotating electric machine 1.

[0025] 1, 4, and 7, the magnetic shield 9 has an extension portion 91 that extends inward in the radial direction X2 to separate the rotor 4 from the resolver coil 812 in the axial direction Y. The extension portion 91 of the magnetic shield 9 is formed with a step from a portion of the magnetic shield 9 that contacts the low permeability portion 7 toward the rotor 4 in the axial direction Y to avoid contact with the resolver coil 812. As shown in FIG. 7, a portion T1 of the extension portion 91 on the inner side X2 in the radial direction X is formed more inward in the radial direction X than a portion T2 of the inner side X2 in the radial direction X of the resolver coil 812 that faces the extension portion 91 in the axial direction Y. The low permeability portion 7 is formed of a flat plate, and a portion T3 of the low permeability portion 7 on the inner side X2 in the radial direction X is formed more outward in the radial direction X than a portion T4 of the outer side X1 in the radial direction X of the resolver coil 812 of the resolver 8 that faces the extension portion 91 in the radial direction X.

[0026] With this configuration, the magnetic shield 9 covers the resolver coil 812 of the resolver stator 81, preventing magnetic flux generated from the stator 3 and rotor 4 from flowing to the resolver coil 812 and preventing a deterioration in the angle detection accuracy of the resolver 8. Furthermore, since the low permeability portion 7 is formed from a flat plate, it is possible to reduce the production cost of the rotating electric machine 1. Furthermore, the low permeability portion 7 is a non-magnetic material with magnetic permeability close to that of air, and is formed from a material with higher conductivity than that of the magnetic shield 9. Specifically, aluminum is used.

[0027] In this way, by using a non-magnetic, highly conductive material for the low permeability portion 7, high-frequency noise that is generated in the resolver 8 due to inverter switching or the like when the rotating electric machine 1 is inverter-driven can be blocked, and deterioration of the angle detection accuracy of the resolver 8 can be prevented. Also, while an example in which aluminum is used for the low permeability portion 7 has been shown, this is not limitative and other non-magnetic, highly conductive materials such as copper may be used. In cases where the resolver 8 is not affected by high-frequency noise, a non-magnetic member made of a non-metallic material such as resin or rubber that does not have high conductivity may be used for the low permeability portion 7. Furthermore, SUS (Steel Use Stainless Steel), which has a lower magnetic permeability than iron-based materials, may be used.

[0028] When a resin material is used for the low permeability portion 7, it is possible to omit providing a fixing portion by, for example, integrally molding the resolver stator 81 and the magnetic shield 9 using the resin material of the low permeability portion 7. Furthermore, as shown in Fig. 8, when, for example, an adhesive or pressure-sensitive adhesive sheet of a resin material having an adhesive function is used as the resin material used for the low permeability portion 7, it is also possible to adhesively fix the resolver stator 81 and the magnetic shield 9 to each other via the resin material of the low permeability portion 7 having an adhesive function. In this case, it is possible to omit providing the fixing holes and fixing portions described above.

[0029] Furthermore, even when the resolver stator 81 and the magnetic shield 9 are fixed to each other using a resin material for the low magnetic permeability portion 7, a redundant fixing configuration may be adopted using fixing portions and fixing holes, etc., from the viewpoint of preventing peeling and reinforcing the low magnetic permeability portion 7 made of a resin material. Furthermore, when a resin material is used for the low magnetic permeability portion 7, the low magnetic permeability portion 7 can also be formed by coating a predetermined surface of the resolver stator 81 or the magnetic shield 9 with a low magnetic permeability resin material. In this case, either the resolver stator 81 or the magnetic shield 9 will be integrally molded with the low magnetic permeability portion 7.

[0030] Then, when fixing the resolver stator 81 or magnetic shield 9 on the side that is not integrally molded, the resolver stator 81, the magnetic shield 9, and the low magnetic permeability portion 7 may be fixed to one another using a common bolt 100 or the like in a fixing hole as a separate fixing portion. Also, in the example in which a resin material is used for the low magnetic permeability portion 7 as shown above, it is also possible to use, for example, rubber, which is a non-metallic material that does not have a high magnetic permeability, such as silicone rubber that has a relatively high heat resistance and a magnetic permeability close to 1, or other heat-resistant rubber such as fluororubber. Also, if the applied rotating electric machine 1 has high cooling performance and is designed to keep the temperature near the resolver stator 81 at a relatively low temperature of around 100°C at most, it is also possible to use, for example, synthetic rubber that has a heat resistance of slightly more than 100°C as the low magnetic permeability portion 7.

[0031] The rotating electric machine of the first embodiment configured as described above has: a shaft; a rotor that rotates together with the shaft; a stator that is arranged radially opposite the rotor with a gap between them; a housing that holds the shaft via a bearing and that houses the rotor and the stator; and a resolver that detects a rotation angle of the rotor, wherein the resolver is arranged between the bearing and the rotor in the axial direction of the shaft, and the resolver has: a resolver rotor that is installed on the outer periphery of the shaft and rotates together with the shaft; and a resolver stator that is arranged radially opposite the resolver rotor with a gap between them, and the resolver stator has: a resolver stator core that has an annular resolver stator core back portion and a plurality of resolver teeth that protrude from the radially inner side of the resolver stator core back portion and are formed at intervals in the circumferential direction; and a plurality of resolver coils that are wound around each of the resolver teeth, A magnetic shield formed in a ring shape around the shaft is provided between the resolver stator and the rotor in the axial direction, and a low-permeability portion is sandwiched between the resolver stator and the magnetic shield in the axial direction and formed of a material having a magnetic permeability lower than that of the magnetic shield.As a result, the magnetic shield can prevent magnetic flux generated from the stator and rotor from flowing into the resolver, and not only can the angle detection accuracy of the resolver be improved, but also, since the low-permeability portion is located between the resolver stator and the magnetic shield, the magnetic shield and the resolver are formed at a certain distance apart, and magnetic flux does not easily pass through the low-permeability portion, the magnetic flux generated from the stator and rotor and flowing in the magnetic shield can be prevented from flowing into the resolver, thereby suppressing the resulting decrease in the angle detection accuracy of the resolver, and a rotating electric machine can be provided that can improve the angle detection accuracy of the resolver.

[0032] Furthermore, according to the rotating electric machine of the first embodiment configured as described above, the resolver stator, the low magnetic permeability portion, and the magnetic shield are fixed to the housing by a common fixing portion. Therefore, the resolver stator, the low magnetic permeability portion, and the magnetic shield can be fixed at the same time by the common fixing portion, thereby improving the productivity of the rotating electric machine and enabling a reduction in the production cost of the rotating electric machine.

[0033] Furthermore, according to the rotating electric machine of embodiment 1 configured as described above, the resolver stator, the low magnetic permeability portion, and the magnetic shield each have fixing holes formed at the same circumferential and radial locations, and the fixing portions are installed in the fixing holes that axially communicate with the resolver stator, the low magnetic permeability portion, and the magnetic shield. Since each fixing hole is configured to penetrate in the axial direction, using each fixing hole makes it easier to fix using a common fixing portion.

[0034] Furthermore, according to the rotating electric machine of the first embodiment configured as described above, the fixing portion is formed by a bolt, so that the resolver stator, the low magnetic permeability portion, and the magnetic shield can be easily fixed at once by a common bolt, thereby reducing the production cost of the rotating electric machine.

[0035] Furthermore, according to the rotating electric machine of embodiment 1 configured as described above, the fixed portion is not in contact with the inner wall of the fixing hole of the resolver stator, and is installed with a predetermined space between the fixed portion and the inner wall of the fixing hole. Therefore, when the fixed portion is made of a magnetic material, by providing a predetermined space between the resolver stator and the fixed portion, it is possible to prevent magnetic flux generated from the stator and rotor from flowing from the fixed portion to the resolver stator, and to prevent deterioration of the angle detection accuracy of the resolver.

[0036] Furthermore, according to the rotating electric machine of embodiment 1 configured as described above, the fixed portion is formed of a non-magnetic material. Therefore, by using a non-magnetic material for the fixed portion, it is possible to prevent magnetic flux generated from the stator and rotor flowing into the magnetic shield from flowing from the fixed portion to the resolver stator, thereby preventing deterioration in the angle detection accuracy of the resolver.

[0037] Furthermore, according to the rotating electric machine of the first embodiment configured as described above, the magnetic shield has an extension portion that extends radially inward and blocks the axial space between the rotor and the resolver coil. Therefore, by covering the resolver coil of the resolver stator with the magnetic shield, it is possible to prevent magnetic flux generated from the stator and rotor from flowing to the resolver coil, and to prevent deterioration of the angle detection accuracy of the resolver.

[0038] Furthermore, according to the rotating electric machine of the first embodiment configured as described above, the low permeability portion is formed of a flat plate, so that the production cost of the low permeability portion can be reduced.

[0039] Furthermore, according to the rotating electric machine of embodiment 1 configured as described above, the low permeability portion is formed of a material having a higher conductivity than the magnetic shield. Therefore, by using a material with a high conductivity for the low permeability portion, when the rotating electric machine is driven by an inverter, for example, it is possible to block high-frequency noise to the resolver generated by inverter switching, etc., and to prevent deterioration of the angle detection accuracy of the resolver.

[0040] Embodiment 2. Fig. 9 is an axial cross-sectional view showing the configuration of a rotating electric machine according to embodiment 2. Fig. 10 is a plan view showing the configuration of a low permeability section as seen from the rotor side of the rotating electric machine shown in Fig. 9. Fig. 11 is a plan view showing the configuration in which a resolver stator, a low permeability section, and a magnetic shield are superimposed as seen from the rotor side of the rotating electric machine shown in Fig. 9. In the figure, parts that are the same as those in embodiment 1 above are given the same reference numerals, and descriptions thereof will be omitted.

[0041] As shown in FIG. 9 , the low permeability portion 77 is sandwiched between the resolver stator 81 and the magnetic shield 9 in the axial direction Y, as in the first embodiment. The low permeability portion 77 is formed of a material having a magnetic permeability lower than that of the magnetic shield 9. In the second embodiment, as shown in FIG. 10 , a plurality of low permeability portions 77 are provided at separate locations in the circumferential direction Z (here, three low permeability portions are provided locally). Each low permeability portion 77 is formed as a hollow cylinder having a fixing hole 70. In FIG. 10 , the position of the outline of the low permeability portion 7 of the first embodiment is indicated by a dotted line in order to compare each low permeability portion 77 of the second embodiment with the low permeability portion 7 of the first embodiment.

[0042] 9, there are mixed regions between the resolver stator 81 and the magnetic shield 9, where the low permeability portions 77 are arranged and where the low permeability portions 77 are not substantially arranged and an air layer 777 with low magnetic permeability is formed. The other configurations are the same as those of the first embodiment.

[0043] By configuring the low permeability portion 77 in this manner, the low permeability portion 77 functions as a spacer for providing a gap between the resolver stator 81 and the magnetic shield 9 in the axial direction Y, and it is possible to secure both a region through the air layer 777 with low magnetic permeability and a region through the low permeability portion 77. This further improves the shielding performance of the magnetic flux generated from the stator 3 and the rotor 4 to the resolver 8. Furthermore, by locally arranging the low permeability portion 77, it is possible to reduce the weight of the low permeability portion 77 and reduce production costs.

[0044] When a configuration is adopted in which both a region through the air layer 777 with low magnetic permeability and a region through the low permeability portion 77 are ensured, particularly when the low permeability portion 77 is made of a material with a higher magnetic permeability than the air layer 777, it is desirable to set the area ratio of the region through the air layer 777 to the region through the low permeability portion 77 in the region sandwiched between the resolver stator 81 and the magnetic shield 9 so that the area ratio of the region through the air layer 777 is higher than that of the region through the low permeability portion 77. This makes it possible to further improve the shielding properties of the magnetic flux generated from the stator 3 and the rotor 4 to the resolver 8 within the constraints on the permeability of the material that can be used for the low permeability portion 77.

[0045] When a resin material is used for the low magnetic permeability portion 77, the resolver stator 81 and the magnetic shield 9 may be integrally molded via the resin, and an adhesive or pressure-sensitive adhesive sheet having an adhesive function may be used. Furthermore, bolts 100 are used as fixing portions that fix the resolver stator 81, the low magnetic permeability portion 77, and the magnetic shield 9, and the bolts 100 are made of a non-magnetic material. In this way, using a non-magnetic material for the fixing portions can prevent the magnetic flux generated by the stator 3 and rotor 4, which flows in the magnetic shield 9, from flowing from the fixing portions to the resolver stator 81, and can prevent deterioration of the angle detection accuracy of the resolver 8.

[0046] Furthermore, an example has been described in which the fixing hole 70 is formed in the low magnetic permeability portion 77, and the fixing holes 80, 90 formed in the resolver stator 81 and the magnetic shield 9 are aligned with the fixing hole 70, and the resolver stator 81 and the magnetic shield 9 are firmly fixed to each other using the bolt 100 that serves as a common fixing portion. However, if only the resolver stator 81 and the magnetic shield 9 are fixed by fixing portions and the low magnetic permeability portion 77 is fixed by being sandwiched between the resolver stator 81 and the magnetic shield 9, the fixing hole 70 formed in the low magnetic permeability portion 77 may be omitted.

[0047] Even when using a low permeability portion 77 without the fixing hole 70, the low permeability portion 77 still functions as a spacer. Therefore, the low permeability portions 77 are disposed in an annular region sandwiched between the resolver stator 81 and the magnetic shield 9, at three or more locations dispersed in the circumferential direction Z. By providing low permeability portions 77 with a predetermined thickness, the distance in the axial direction Y of an air layer 777 formed between the resolver stator 81 and the magnetic shield 9, i.e., the distance in the axial direction Y between the resolver stator 81 and the magnetic shield 9, can be set to a predetermined distance. Note that when using a low permeability portion 77 without the fixing hole 70, the low permeability portion 77 without the fixing hole 70 is disposed in a position that does not block the fixing holes 80, 90 formed in the resolver stator 81 and the magnetic shield 9 in the axial direction Y.

[0048] In the above embodiment, the low permeability portions 77 are arranged at three locations in the circumferential direction Z as spacers for uniformly distributing the distance of the air layer 777 in the axial direction Y, but the present invention is not limited to this. For example, as a preferred configuration, it is effective to arrange an annular, flat-plate-shaped low permeability portion concentrically in a region facing the resolver stator 81 and the magnetic shield 9 in the axial direction Y. When arranging such an annular low permeability portion, a configuration may be adopted in which fixing holes are formed and the resolver stator 81 and the magnetic shield 9 are firmly fixed to each other using bolts 100 that serve as fixing portions common to the resolver stator 81 and the magnetic shield 9, or, as in the configuration exemplified above, fixing holes may be omitted and the resolver stator 81 and the magnetic shield 9 may be sandwiched between them, and annular low permeability portions may be formed and arranged at concentric positions offset to the inner side X2 or the outer side X1 in the radial direction X between the fixing holes 80, 90 formed in the resolver stator 81 and the magnetic shield 9.

[0049] The rotating electric machine of the second embodiment configured as described above has the same effects as the first embodiment, and in addition, the low permeability portions are arranged at multiple locations in the circumferential direction between the resolver stator and the magnetic shield in an axial direction and spaced apart from each other, and an air space where no low permeability portion is arranged is formed in the radial direction between the resolver stator and the magnetic shield in the axial direction, thereby ensuring both an area with an air space with low magnetic permeability and an area with a low permeability portion, thereby further improving the ability to block magnetic flux generated from the stator and rotor to the resolver. Furthermore, by locally arranging the low permeability portions, it is possible to reduce the weight and production costs of the low permeability portions.

[0050] Embodiment 3. Fig. 12 is an axial cross-sectional view of a partial configuration of a rotating electric machine according to embodiment 3. Fig. 13 is a plan view of a state in which a resolver stator, a low magnetic permeability portion, and a magnetic shield are fixed, as viewed from the rotor side according to embodiment 3. In the figure, parts that are the same as those in the above embodiments are given the same reference numerals, and description thereof will be omitted.

[0051] 12 , the shaft 2 is formed with a flange portion 200 having a locally increased diameter at a position facing the magnetic shield 9 in the radial direction X. The low permeability portion 7 is formed of a material such as aluminum whose magnetic permeability is equivalent to that of air. The distance in the radial direction X from the inner side X2 of the magnetic shield 9 in the radial direction X to the flange portion 200 of the shaft 2 is defined as a distance W1.

[0052] Furthermore, the distance in the radial direction X of the gap G2 between the resolver stator 81 and the resolver rotor 82 is defined as distance W2 (i.e., the distance in the radial direction X from the outer side X1 of the resolver rotor 82 in the radial direction X to the inner side X2 of the resolver stator 81 in the radial direction X). The thickness in the axial direction Y of the low magnetic permeability portion 7 is defined as thickness W3 (i.e., the thickness W3 is the shortest distance between the points where the resolver stator core 811 and the magnetic shield 9 face each other in the axial direction Y). When these settings are made, each member is formed so that "W1 < W2 + W3" holds.

[0053] According to the rotating electric machine of the third embodiment configured as described above, the components are formed so that "W1<W2+W3" is satisfied, and therefore the magnetic resistance between the magnetic shield 9 and the shaft 2 is smaller than the sum of the magnetic resistance of the gap G2 between the resolver rotor 82 and the resolver stator 81 and the magnetic resistance between the resolver stator 81 and the magnetic shield 9. Therefore, the magnetic flux generated from the stator 3 and rotor 4 and flowing to the resolver 8 through the shaft 2 of the rotating electric machine 1 is more likely to flow from the shaft 2 to the magnetic shield 9 than from the shaft 2 to the resolver rotor 82 to the resolver stator 81 to the magnetic shield 9. This further prevents the magnetic flux generated from the stator 3 and rotor 4 from flowing into the resolver 8. This prevents the angle detection accuracy of the resolver 8 from deteriorating.

[0054] Although an example in which the shaft 2 is provided with a flange portion 200 has been shown, this is not limited to this, and for example, a ring-shaped magnetic material such as iron may be fixed to the relevant part of the shaft 2 by press-fitting or the like to form a protrusion.

[0055] The rotating electric machine of the third embodiment configured as described above has the same effects as the above embodiments, and also has the following relationship: W1 is the radial distance between the radial inside of the magnetic shield and the shaft, W2 is the radial distance of the gap between the resolver rotor and the resolver stator, and W3 is the axial thickness of the low magnetic permeability portion. Therefore, the magnetic resistance between the magnetic shield and the shaft is smaller than the sum of the magnetic resistance of the gap between the resolver rotor and the resolver stator and the magnetic resistance between the resolver stator and the magnetic shield. This makes it easier for the magnetic flux generated from the stator and rotor and flowing through the shaft of the rotating electric machine to the resolver to flow from the shaft to the magnetic shield than from the shaft to the resolver rotor to the resolver stator to the magnetic shield. This makes it possible to further prevent the magnetic flux generated from the stator and rotor from flowing into the resolver, and prevents a deterioration in the angle detection accuracy of the resolver.

[0056] Embodiment 4 Fig. 14 is a cross-sectional view showing an axial section of a rotating electric machine according to embodiment 4. Fig. 15 is a plan view showing the configuration of a magnetic shield as seen from the resolver side of the rotating electric machine shown in Fig. 14.

[0057] 14 and 15 , the magnetic shield 9 has a cylindrical portion 901 extending on the outer periphery of the magnetic shield 9 on the side opposite to the stator 3 in the axial direction Y so as to cover the outer periphery of the outer periphery X1 of the resolver stator 81 in the radial direction X. In addition, the plate thickness W4 (see FIG. 12 ) of the magnetic shield 9 is set so as to be equal to or less than the saturation magnetic flux density of the material of the magnetic shield 9 in the operating range of the rotating electric machine 1. The other configurations are the same as those of the first embodiment.

[0058] According to the fourth embodiment configured as described above, the cylindrical portion 901 of the magnetic shield 9 can further prevent magnetic flux generated from the stator 3 and the rotor 4 from flowing from the outside X1 in the radial direction X of the resolver stator 81 from the stator 3, thereby further improving the angle detection accuracy of the resolver 8. Furthermore, the plate thickness W4 of the magnetic shield 9 is formed to be equal to or less than the saturation magnetic flux density of the material of the magnetic shield 9. As a result, the magnetic flux density of the magnetic shield 9 becomes equal to or less than the saturation magnetic flux density, and magnetic flux generated from the stator 3 and the rotor 4 and flowing through the magnetic shield 9 can be prevented from leaking and flowing into the resolver stator 81, thereby preventing a deterioration in the angle detection accuracy of the resolver 8.

[0059] Since the thickness W4 of the magnetic shield 9 is formed to be a thickness that is equal to or less than the saturation magnetic flux density of the material of the magnetic shield 9 in the operating range of the rotating electric machine 1, the distance in the axial direction Y from the resolver 8 may be shortened, the thickness W3 (see FIG. 12) of the low permeability portion 7 may be reduced, and the production cost of the low permeability portion 7 may be reduced. Note that, as long as the angle detection accuracy of the resolver 8 remains within an acceptable range during operation of the rotating electric machine 1, the thickness W4 of the magnetic shield 9 may be a thickness that is equal to or greater than the saturation magnetic flux density of the material of the magnetic shield 9.

[0060] The rotating electric machine of the fourth embodiment configured as described above has the same effects as the above-described embodiments, and furthermore, the magnetic shield has a cylindrical portion formed by extending the radial outside of the magnetic shield in the axial direction so as to cover the radial outside of the resolver stator. Therefore, the cylindrical portion can prevent magnetic flux generated from the stator and rotor from flowing in from the radial outside of the resolver stator, and further enables improvement of the angle detection accuracy of the resolver.

[0061] Furthermore, according to the rotating electric machine of the fourth embodiment configured as described above, the thickness of the magnetic shield is set to a thickness that is equal to or less than the saturation magnetic flux density of the material of the magnetic shield in the operating range of the rotating electric machine, so that the magnetic flux generated from the stator and rotor flowing through the magnetic shield can be prevented from leaking and flowing into the resolver stator, thereby preventing a deterioration in the angle detection accuracy of the resolver. In addition, the axial distance from the resolver can be shortened, which allows the thickness of the low permeability portion to be reduced and reduces the production cost of the low permeability portion.

[0062] Although various exemplary embodiments and examples are described in this disclosure, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not illustrated are contemplated within the scope of the technology disclosed in this specification. For example, this includes cases where at least one component is modified, added, or omitted, and further cases where at least one component is extracted and combined with components of another embodiment.

[0063] REFERENCE SIGNS LIST 1 Rotating electric machine, 100 Volt, 2 Shaft, 200 Flange portion, 3 Stator, 31 Stator core, 32 Coil, 4 Rotor, 41 Rotor core, 42 Permanent magnet, 5 Housing, 51 Protrusion portion, 500 Positioning pin, 6 Bearing, 7 Low magnetic permeability portion, 77 Low magnetic permeability portion, 70 Fixing hole, 700 Positioning hole, 777 Air layer, 8 Resolver, 80 Fixing hole, 800 Recess, 801 Resolver stator core back portion, 802 Resolver teeth portion, 81 Resolver stator, 811 Resolver stator core, 812 Resolver coil, 82 Resolver rotor, 9 Magnetic shield, 90 Fixing hole, 900 Positioning hole, 901 Cylindrical portion, 91 Extension portion, G1 Gap, G2 Gap, Q Central axis, X Radial direction, X1 Outer side, X2 Inner side, Y axis direction, Z circumferential direction, W1 distance, W2 distance, W3 thickness, W4 plate thickness.

Claims

1. A rotary electric machine having: a shaft; a rotor that rotates together with the shaft; a stator that is arranged radially opposite the rotor with a gap between them; a housing that holds the shaft via a bearing and that houses the rotor and the stator; and a resolver that detects a rotation angle of the rotor, wherein the resolver is arranged between the bearing and the rotor in the axial direction of the shaft, and the resolver has: a resolver rotor that is installed on the outer periphery of the shaft and rotates together with the shaft; and a resolver stator that is arranged radially opposite the resolver rotor with a gap between them, and the resolver stator has: a resolver stator core that has an annular resolver stator core back portion and a plurality of resolver teeth that protrude from the radially inner side of the resolver stator core back portion and are formed at intervals in the circumferential direction; and a plurality of resolver coils that are wound around each of the resolver teeth, a magnetic shield formed in an annular shape around the shaft between the resolver stator and the rotor in the axial direction; and a low-permeability portion sandwiched and installed between the resolver stator and the magnetic shield in the axial direction, and formed of a material having a magnetic permeability lower than that of the magnetic shield.

2. The rotating electric machine according to claim 1, wherein the resolver stator, the low magnetic permeability portion, and the magnetic shield are fixed to the housing by a common fixing portion.

3. A rotating electric machine as described in claim 2, wherein the resolver stator, the low magnetic permeability portion, and the magnetic shield each have a fixing hole formed at the same location in the circumferential and radial directions, and the fixing portion is installed within each of the fixing holes that communicate with the resolver stator, the low magnetic permeability portion, and the magnetic shield in the axial direction.

4. A rotating electric machine according to claim 3, wherein the fixing portion is formed by a bolt.

5. A rotating electric machine according to claim 3 or 4, wherein the fixing portion does not contact the inner wall of the fixing hole of the resolver stator, and is installed with a predetermined space between the fixing portion and the inner wall of the fixing hole.

6. A rotating electric machine according to any one of claims 2 to 5, wherein the fixed portion is formed of a non-magnetic material.

7. A rotating electric machine according to any one of claims 1 to 6, wherein the low permeability portions are arranged axially between the resolver stator and the magnetic shield, at multiple locations spaced apart in the circumferential direction, and an air space where no low permeability portions are arranged is formed radially between the resolver stator and the magnetic shield in the axial direction.

8. A rotating electric machine according to any one of claims 1 to 7, wherein the magnetic shield has an extension portion extending radially inward to shield the rotor from the resolver coil in the axial direction.

9. A rotating electric machine according to any one of claims 1 to 8, wherein the low magnetic permeability portion is formed of a flat plate.

10. A rotating electric machine according to any one of claims 1 to 9, wherein the relationship W1 < W2 + W3 holds, where W1 is the radial distance between the radial inside of the magnetic shield and the shaft, W2 is the radial distance of the gap between the resolver rotor and the resolver stator, and W3 is the axial thickness of the low magnetic permeability portion.

11. A rotating electric machine according to any one of claims 1 to 10, wherein the magnetic shield has a cylindrical portion formed by extending the radial outside of the magnetic shield in the axial direction so as to cover the radial outside of the resolver stator.

12. A rotating electric machine according to any one of claims 1 to 11, wherein the low permeability portion is formed of a material having a higher electrical conductivity than the magnetic shield.

13. A rotating electric machine according to any one of claims 1 to 12, wherein the thickness of the magnetic shield is formed to be equal to or less than the saturation magnetic flux density of the material of the magnetic shield in the operating range of the rotating electric machine.

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