Winding field rotor

Abstract

This rotor (60) is provided with: a rotor core (61) that comprises a plurality of principal pole sections (62) disposed at magnetic poles arrayed in a circumferential direction; a field winding (70) disposed so as to encircle the principal pole sections; and a metal annular member (102) disposed so as to surround the principal pole sections and the field winding from the radially outer side. The rotor is disposed in a rotating electrical machine (40) so as to face a stator (50) in the radial direction. The annular member comprises, in the circumferential direction, first portions (141) that are on the radially outer side of the principal pole sections, and second portions (142) that are on the radially outer side of the field winding. The first portions and the second portions differ in magnetic flux density, and the magnetic flux density is relatively higher in the first portions than in the second portions.

Description

Wound field rotor CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Application No. 2024-064014, filed on April 11, 2024, the contents of which are incorporated herein by reference.

[0002] The disclosure herein relates to wound field rotors.

[0003] A wound-field rotating electric machine includes a stator having a stator winding and a rotor having a field winding. The rotor includes a rotor core having a plurality of main poles (magnetic salient poles), and the field winding is wound around the main poles. Patent Document 1 also discloses a rotor structure in which a metal wire is wound spirally around the outer periphery of the field winding.

[0004] Japanese Patent Application Laid-Open No. 2013-9553

[0005] When a stator is disposed radially outside the rotor, the outer periphery of the rotor transmits magnetic flux to the stator, and it is desirable for the wire wound around the outer periphery of the rotor to be magnetic. However, if the magnetic flux density of the wire is high, magnetic flux leakage may occur, which may result in a decrease in motor torque. In this regard, the technology described in Patent Document 1 describes that the wire is wound uniformly around the outer periphery of the rotor, and there is thought to be room for technical improvement.

[0006] The present disclosure has been made in consideration of the above circumstances, and has an object to provide a wound field rotor that can improve motor performance.

[0007] The present disclosure relates to a wound field rotor arranged radially opposite a stator in a rotary electric machine, comprising: a rotor core having a plurality of main pole portions provided for each circumferentially arranged magnetic pole; a field winding provided in a state where it is wrapped around each of the main pole portions; and a metallic circular member provided so as to surround each of the main pole portions and the field winding from the radial outside, wherein the circular member has, in the circumferential direction, a first portion that is radially outside the main pole portions and a second portion that is radially outside the field winding, the first portion and the second portion having different magnetic flux densities, the first portion having a relatively higher magnetic flux density than the second portion.

[0008] In a rotating electric machine, when each main pole portion of a rotor core and a field winding are surrounded by a metal annular member, displacement and deformation of the field winding are suppressed even when centrifugal force acts on the field winding during rotor rotation. Furthermore, on the outer periphery of the rotor, the radially outer side of the main pole portion transmits magnetic flux to the stator, and a high magnetic flux density is desirable. On the other hand, if the magnetic flux density of the annular member is high radially outside the field winding, magnetic flux leakage occurs, which may result in a decrease in motor torque. In consideration of this issue, the magnetic flux density of the annular member is made different between a first portion radially outside the main pole portion and a second portion radially outside the field winding, with the first portion having a higher magnetic flux density than the second portion. This ensures proper transmission of magnetic flux between the rotor and the stator. As a result, motor performance can be improved.

[0009] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which Fig. 1 is an overall configuration diagram of a control system for a rotating electric machine, Fig. 2 is a diagram showing an inverter and its peripheral configuration, Fig. 3 is a cross-sectional view of a rotor and a stator, Fig. 4 is a diagram showing an electric circuit provided in the rotor, Fig. 5 is a perspective view showing the overall configuration of the rotor, Fig. 6 is a perspective view showing the rotor with an annular member and a coil end cover removed, Fig. 7 is an exploded perspective view of the rotor, Fig. 8 is a longitudinal cross-sectional view of the rotor, and Fig. 9 is a diagram showing a main portion of the rotor. 10 is a cross-sectional view showing the cross-sectional structure of a portion of the rotor main part, FIG. 11 is a cross-sectional view showing the cross-sectional structure of a portion of the rotor main part, FIG. 12 is a longitudinal cross-sectional view showing the winding structure of the wire material in the circular member, FIG. 13 is a cross-sectional view showing another configuration of the circular member, FIG. 14 is a cross-sectional view showing another configuration of the circular member, FIG. 15 is a cross-sectional view showing another configuration of the circular member, and FIG. 16 is a cross-sectional view showing another configuration of the circular member.

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A wound-field rotating electric machine according to an embodiment of the present disclosure is used as a power source for driving electric vehicles such as electric vehicles and hybrid vehicles.

[0011] First, a control system including a rotating electric machine will be described with reference to Fig. 1. The control system includes a DC power supply 10, an inverter 20, a control device 30, and a rotating electric machine 40. The rotating electric machine 40 is a self-excited wound field type synchronous machine. For example, the rotating electric machine 40, the inverter 20, and the control device 30 may be configured as an electromechanical integrated drive device, or the rotating electric machine 40, the inverter 20, and the control device 30 may each be configured as a separate component.

[0012] The rotating electric machine 40 includes a housing 41, and a stator 50 and a rotor 60 housed in the housing 41. The rotating electric machine 40 of this embodiment is an inner rotor type rotating electric machine in which the rotor 60 is disposed radially inside the stator 50.

[0013] The stator 50 includes a stator core 51 and a stator winding 52. The stator winding 52 is made of, for example, copper wire, and includes U-, V-, and W-phase windings 52U, 52V, and 52W that are arranged with an electrical angle offset of 120° from one another.

[0014] The rotor 60 includes a rotor core 61 and a field winding 70. The field winding 70 is preferably made of a conductor material such as aluminum wire, which has a low specific gravity and is easily formed. The conductor material of the field winding 70 is not limited to aluminum wire, and may be copper wire or CNT (carbon nanotube), for example. A rotating shaft 32 is attached to the center hole of the rotor core 61. The rotating shaft 32 is rotatably supported by bearings 42 and 43 in the housing 41.

[0015] As shown in FIG. 2 , the inverter 20 includes a series connection of upper-arm switches SUp, SVp, and SWp for U, V, and W phases and lower-arm switches SUn, SVn, and SWn for U, V, and W phases. First ends of U-, V-, and W-phase windings 52U, 52V, and 52W are connected to the connection points between the upper-arm switches SUp, SVp, and SWp and the lower-arm switches SUn, SVn, and SWn for each phase. Second ends of the U-, V-, and W-phase windings 52U, 52V, and 52W are connected at the neutral point. That is, in this embodiment, the stator winding 52 is star-connected. However, the stator winding 52 may also be delta-connected. In this embodiment, each of the switches SUp to SWn is, for example, an IGBT. A freewheel diode is connected in antiparallel to each of the switches SUp to SWn.

[0016] The collectors of the upper arm switches SUp, SVp, SWp of each phase are connected to the positive terminal of a DC power supply 10. The emitters of the lower arm switches SUn, SVn, SWn of each phase are connected to the negative terminal of the DC power supply 10. A smoothing capacitor 11 is connected in parallel to the DC power supply 10.

[0017] Next, the stator 50 and the rotor 60 will be described with reference to FIG.

[0018] The stator 50 and the rotor 60 are both arranged coaxially with the rotating shaft 32. In the following description, the direction in which the rotating shaft 32 extends is referred to as the axial direction, the direction extending radially from the center of the rotating shaft 32 is referred to as the radial direction, and the direction extending circumferentially around the rotating shaft 32 is referred to as the circumferential direction.

[0019] The stator core 51 is made of laminated steel plates made of a soft magnetic material and has an annular back yoke 51a and multiple teeth 51b protruding radially inward from the back yoke 51a. Multiple slots 54 are formed between adjacent teeth 51b in the circumferential direction. The stator winding 52 is formed by accommodating the phase windings of each phase in a predetermined order in each of these slots 54. For example, the stator 50 may employ a segment coil structure using multiple conductor segments. However, the structure of the stator winding 52 is arbitrary.

[0020] The rotor core 61 is made of a soft magnetic material, for example, laminated steel plates. The rotor core 61 has a cylindrical portion 61a and a plurality of main pole portions 62 extending radially outward from the cylindrical portion 61a. A field winding 70 is wound around the main pole portions 62 by concentrated winding. In this embodiment, eight main pole portions 62 are provided at equal intervals in the circumferential direction.

[0021] The field winding 70 includes a first winding portion 71 and a second winding portion 72. The first winding portion 71 is wound radially outward around each main pole portion 62, and the second winding portion 72 is wound radially inward relative to the first winding portion 71. In each main pole portion 62, the winding directions of the conductor wire in the first winding portion 71 and the second winding portion 72 are the same. Furthermore, among circumferentially adjacent main pole portions 62, the winding direction of each winding portion 71, 72 wound around one is opposite to the winding direction of each winding portion 71, 72 wound around the other. Therefore, the magnetization directions of circumferentially adjacent main pole portions 62 are opposite to each other. In the rotor 60, each main pole portion 62 in the rotor core 61 and the field winding 70 wound around each main pole portion 62 form a plurality of magnetic poles (field poles) arranged circumferentially.

[0022] 4 is a diagram showing an electric circuit including the first and second winding portions 71, 72 in the rotor 60. The first winding portion 71 and the second winding portion 72 are connected in series by connecting the second end 71b of the first winding portion 71 to the first end 72a of the second winding portion 72. A diode 91 and a capacitor 92 are connected to the second end 71b of the first winding portion 71 in parallel with the second winding portion 72. A diode 93 and a capacitor 94 are connected in series to the series connection of the first winding portion 71 and the second winding portion 72. The capacitors 92, 94 are, for example, ceramic capacitors or film capacitors.

[0023] The diode 91 has a cathode connected to the first end 72a of the second winding portion 72 and an anode connected to the second end 72b of the second winding portion 72. As a result, in a closed circuit including the second winding portion 72 and the diode 91, current flows in one direction, from the anode side to the cathode side of the diode 91. Furthermore, the diode 93 has a cathode connected to the first end 71a of the first winding portion 71 and an anode connected to the second end 72b of the second winding portion 72. As a result, the field current flowing through each winding portion 71, 72 is rectified. In this embodiment, the number of windings of the second winding portion 72 is greater than the number of windings of the first winding portion 71.

[0024] Returning to the description of FIG. 2 , the control device 30 is an electronic control unit (EC) primarily composed of a microcomputer 31. The microcomputer 31 includes a central processing unit (CPU). The functions provided by the microcomputer 31 can be provided by software stored in a physical memory device and a computer executing the software, software alone, hardware alone, or a combination thereof. For example, if the microcomputer 31 is provided by a hardware electronic circuit, the functions can be provided by a digital circuit including multiple logic circuits or an analog circuit. For example, the microcomputer 31 executes a program stored in a non-transitory tangible storage medium (NSS) that serves as its own storage unit. The program includes a program for controlling the rotating electric machine 40. A method corresponding to the program is executed by executing a set of instructions that constitute the program. The storage unit is, for example, a non-volatile memory. The program stored in the storage unit can be updated via a communication network such as the Internet, for example, via OTA (Over the Air).

[0025] The control device 30 generates drive signals that turn on and off the switches SUp to SWn that configure the inverter 20. Specifically, the control device 30 generates drive signals that turn on and off the switches SUp to SWn and outputs the generated drive signals to the gates of the switches SUp to SWn in order to convert the DC power output from the DC power supply 10 into AC power and supply it to the U-, V-, and W-phase windings 52U, 52V, and 52W. As a result, the upper and lower arm switches in each phase are alternately turned on with dead times therebetween.

[0026] The control device 30 turns on and off the switches SUp to SWn so that a composite current of a fundamental current and a high-frequency current (specifically, a high-frequency excitation current) having a frequency higher than that of the fundamental current flows through each of the phase windings 52U, 52V, and 52W. The fundamental current is a current that mainly serves to generate torque in the rotary electric machine 40. The high-frequency current is a current that mainly serves to excite the first and second winding portions 71 and 72 that constitute the field winding 70, thereby inducing a field current in the field winding 70. The phase currents flowing through the phase windings 52U, 52V, and 52W are shifted by 120 electrical degrees.

[0027] The high-frequency current flowing through the stator winding 52 may be a harmonic current whose fluctuating frequency is N times (N is an integer of 2 or more) the frequency of the fundamental current, or may be a current whose fluctuating frequency is different from N times the frequency of the fundamental current.

[0028] When a high-frequency current flows through the stator winding 52, a voltage is induced in the first and second winding portions 71 and 72, causing a field current to flow. The induced voltages in the first and second winding portions 71 and 72 are, for example, in phase. The currents IL1 and IL2 flowing through the first and second winding portions 71 and 72 contain frequency components of the high-frequency current.

[0029] In the electric circuit shown in Figure 4, when the first and second winding portions 71, 72 are excited by energizing the stator winding 52, a current flows from the first winding portion 71 to the second winding portion 72. Furthermore, when the voltage across the second winding portion 72 exceeds the forward voltage of the diode 91, a current IL2, which is greater than the current IL1 flowing through the first winding portion 71, flows through the closed circuit including the second winding portion 72 and the diode 91. The current flowing through the closed circuit including the second winding portion 72 and the diode 91 increases the DC component of the field current. This increases the DC component of the magnetic flux of the rotor 60, thereby increasing the torque of the rotating electric machine 40.

[0030] Next, the configuration of the rotor 60 will be described in more detail. Fig. 5 is a perspective view showing the overall configuration of the rotor 60, and Fig. 6 is a perspective view showing the rotor 60 with the ring member 102 covering the rotor main section 101 and the coil end covers 103 and 104 removed. Fig. 7 is an exploded perspective view of the rotor 60, and Fig. 8 is a longitudinal cross-sectional view of the rotor 60.

[0031] The rotor 60 is broadly divided into a rotor main section 101, a cylindrical ring member 102 provided to surround the outer periphery of the rotor main section 101, coil end covers 103 and 104 attached to one and the other axial ends of the rotor main section 101, and a busbar module 105 and a circuit module 106 provided at one of both axial ends of the rotor main section 101. The rotor main section 101 includes a rotor core 61 and a field winding 70, and the rotating shaft 32 is assembled to the center hole of the rotor core 61. The field winding 70 is made up of a plurality of winding units 110 arranged circumferentially. The coil end covers 103 and 104 are provided to cover the coil ends of the field winding 70 on both axial sides.

[0032] The busbar module 105 and the circuit module 106 are fixed to the rotating shaft 32 with the rotating shaft 32 inserted through each hollow portion, so that the busbar module 105 and the circuit module 106 are provided at positions axially facing the coil end portions of the field winding 70. The busbar module 105 has a plurality of bus bars for electrically connecting the winding units 110 for each magnetic pole.

[0033] The circuit module 106 includes a component holder 107 that houses electrical components, and a heat sink 108 that is placed over the component holder 107. The component holder 107 and the heat sink 108 are integrated with their axial end faces joined together. The component holder 107 holds diodes 91 and 93 and capacitors 92 and 94 as electrical components.

[0034] The heat sink 108 is fixed to one of the axial ends of the component holder 107, opposite the rotor core 61 (the right side in the figure). The heat sink 108 is made of, for example, aluminum. By fixing the heat sink 108 to the axial end face of the component holder 107, heat generated in the diodes 91 and 93 and the capacitors 92 and 94 when current is applied to the component holder 107 is released via the heat sink 108.

[0035] The circular member 102 is formed by using a metal wire 131 and winding the wire 131 in multiple layers around the outer periphery of the plurality of winding units 110 assembled to the rotor core 61. The circular member 102 surrounds each main pole 62 of the rotor core 61 and the field winding 70 from the radially outer side. The circular member 102 corresponds to an outer periphery covering portion that covers the main pole 62 and the field winding 70 from the outer periphery side.

[0036] The rotor 60 is provided with coil end covers 103, 104 on both axial sides of a circular member 102. The axial range in which the circular member 102 is provided is a range that radially overlaps with the rotor core 61, and this range X is shown in Figure 8. In range X, the main pole portions 62 and winding units 110 are arranged alternately in the circumferential direction, and the circular member 102 is formed by spirally and multiple-wound wire 131 around the radially outer sides of each of the main pole portions 62 and winding units 110.

[0037] Fig. 9 is an exploded perspective view of the winding unit 110 in the rotor main section 101, and Fig. 10 is a cross-sectional view showing the cross-sectional structure of a portion of the rotor main section 101. Note that Fig. 10 depicts the annular member 102 shown in Fig. 5 and other figures as a structure for holding the field winding 70 wound around the main pole section 62 of the rotor core 61.

[0038] The rotor main section 101 has a plurality of winding units 110, one for each magnetic pole of the rotor 60. Each winding unit 110 is formed in an annular shape with the axial direction as the longitudinal direction, and is assembled to the rotor core 61 with the main pole section 62 of the rotor core 61 inserted into its hollow section. In this embodiment, the winding units 110 form a "pole coil."

[0039] The winding unit 110 has a first coil module 111 that is located on the radially outer side when attached to the main pole portion 62, and a second coil module 112 that is located on the radially inner side. The first coil module 111 is a coil module that corresponds to the first winding portion 71, and the second coil module 112 is a coil module that corresponds to the second winding portion 72.

[0040] The first coil module 111 has an annular coil body 121 formed by multiple windings of a conductor material made of a rectangular wire in the circumferential and radial directions, and a thin plate-like insulator 122 provided integrally with the coil body 121. The insulator 122 has a portion that extends circumferentially and covers the outer peripheral portions on the radially outer and inner sides of the coil body 121, and a portion that extends radially and covers the hollow portion of the coil body 121. In other words, the outer peripheral portion on the radially outer side and the inner peripheral portion and hollow portion of the coil body 121 are insulated and coated with the insulator 122.

[0041] The second coil module 112 has an annular coil body 123 formed by multiple windings of a conductor material made of a rectangular wire in the circumferential and radial directions, and a thin plate-like insulator 124 provided integrally with the coil body 123. The insulator 124 has a portion that extends circumferentially and covers the outer peripheral portions on the radially outer and inner sides of the coil body 123, and a portion that extends radially and covers the hollow portion of the coil body 123. In other words, the outer peripheral portion on the radially outer side, the inner peripheral portion on the radially inner side, and the hollow portion of the coil body 123 are insulated and coated with the insulator 124.

[0042] The coil body 121 of the first coil module 111 is, for example, an α-winding coil in which a conductive wire is wound in an α-winding manner. The coil body 123 of the second coil module 112 is a continuously wound coil in which a conductive wire is continuously wound in a predetermined circumferential direction. Two conductive wire ends 125 extend axially in the first coil module 111, and two conductive wire ends 126 extend axially in the second coil module 112. In each of the winding units 110 arranged circumferentially, the conductive wire ends 125, 126 are connected to each other, thereby connecting the multiple first coil modules 111 provided on each main pole portion 62 in series, and connecting the multiple second coil modules 112 provided on each main pole portion 62 in series.

[0043] The conductor wire used for the coil bodies 121, 123 is, for example, a flat wire having a substantially rectangular cross section (specifically, a substantially rectangular shape). The flat wire consists of a conductor portion made of aluminum or the like and an insulating layer covering the conductor portion. However, a round wire having a circular cross section can also be used as the conductor wire. The coil structure of each coil module 111, 112 is optional; for example, the coil bodies 121, 123 can both be continuous wound coils.

[0044] 10 , the first coil module 111 has two radially wound layers of conductor wire, while the second coil module 112 has twelve radially wound layers. Each of the coil modules 111, 112 may have any number of layers, but it is preferable that the number of layers in the second coil module 112 is greater than that of the first coil module 111. The coil modules 111, 112 have different numbers of circumferential windings (i.e., the number of rows of conductor wire in the circumferential direction), with the number of windings being greater on the radially outer side than on the radially inner side. This improves the space factor of the field winding 70.

[0045] Next, the configuration of the circular member 102 will be described. Fig. 11 is a horizontal cross-sectional view showing the cross-sectional structure of a portion of the rotor main section 101. Fig. 12 is a vertical cross-sectional view showing the winding structure of the wire rod 131 around the circular member 102. Note that Fig. 11 shows a simplified configuration of the winding unit 110. In Fig. 12, the left-right direction is the axial direction, and the up-down direction is the radial direction.

[0046] As shown in FIG. 12 , the wires 131 are wound radially in multiple layers (four layers in the figure) while contacting each other in the axial direction. The wires 131 are preferably steel flat wires having a rectangular cross section. The wires 131 are also preferably magnetic materials, specifically SUS430, SUS631, piano wire, or the like. By using flat wires as the wires 131, gaps are less likely to form between the wires 131 in the annular member 102. This prevents the wires 131 from collapsing or deforming in the annular member 102. Furthermore, the space factor in the annular member 102 is increased, thereby enhancing the strength of the annular member 102.

[0047] Furthermore, the wire rods 131 are wound around the circular member 102 in a linearly aligned state in both the axial and radial directions. In this case, because the wire rods 131 are wound around the circular member 102 in an axially aligned state, the outer circumferential surface (the radially outer circumferential surface) of the circular member 102 is flat. Therefore, the mechanical space between the rotor 60 and the stator 50 (the gap between the outer circumferential surface of the circular member 102 and the stator 50) can be kept constant in the axial direction. Furthermore, because the wire rods 131 are wound around the circular member 102 in a radially aligned state, the circular member 102 is divided into predetermined intervals in the axial direction. Therefore, eddy currents are reduced in the circular member 102.

[0048] The annular member 102 and the coil end covers 103, 104 are provided radially outside the main pole portion 62 and the field winding 70, and are continuous in the axial direction with their axial end faces facing each other.

[0049] As shown in FIG. 11 , the circular member 102 has first portions 141 located radially outward of the main pole portion 62 and second portions 142 located radially outward of the field winding 70 (winding unit 110) alternately arranged in the circumferential direction. Furthermore, the circular member 102 does not have a uniform magnetic flux density in the circumferential direction, with the magnetic flux density differing between the first portions 141 and the second portions 142. Specifically, the magnetic flux density is relatively higher in the first portions 141 than in the second portions 142. In this case, the average value of the magnetic flux density (average magnetic flux density) within the first portions 141 is higher than the average magnetic flux density within the second portions 142. In the configuration shown in FIG. 11 , in the circular member 102, the first portions 141 are high-magnetic flux density portions 151 with a relatively high magnetic flux density, and the second portions 142 are low-magnetic flux density portions 152 with a relatively low magnetic flux density. The first portion 141 and the second portion 142 preferably have different magnetic flux densities due to the crystal structures of the wire material 131 being different from each other.

[0050] As a specific configuration of the circular member 102, when the magnetic flux density of the circular member 102 is uniform around the entire circumference, the magnetic flux density B50 [T] when the magnetizing force is 5000 A / m may be, for example, B50 = 1.56 "T." On the other hand, when the magnetic flux density is made different between the first portion 141 and the second portion 142 of the circular member 102, for example, the magnetic flux density of the first portion 141 may be B50 = 1.56 "T," and the magnetic flux density of the second portion 142 may be B50 = 0.7 "T."

[0051] On the outer periphery of the rotor 60, the radially outer side of the main pole portion 62 is a portion that transmits magnetic flux to the stator 50, and the high magnetic flux density of the first portion 141 on the radially outer side of the main pole portion 62 ensures that magnetic flux is transmitted appropriately between the rotor 60 and the stator 50. Furthermore, if the magnetic flux density is high on the radially outer side of the field winding 70, magnetic flux leakage occurs, which may result in a decrease in motor torque. In this regard, the high magnetic flux density of the second portion 142 on the radially outer side of the field winding 70 suppresses magnetic flux leakage.

[0052] More specifically, the configuration of the circular member 102 may be such that the circular member 102 is formed by winding the wire 131 around the outer periphery of the main pole portion 62 of the rotor core 61 and the field winding 70, and then the circular member 102 is subjected to a partially different heat treatment (annealing treatment) to recrystallize the wire 131. For example, the second portion 142, which is radially outward of the field winding 70, may be subjected to heat treatment at a higher temperature than the first portion 141 to reduce the magnetic flux density. When the circular member 102 is heat-treated, a heat dissipation member that suppresses a temperature rise during heat treatment may be attached to the first portion 141 of the portions 141, 142, so that the first portion 141 is kept at a lower temperature than the second portion 142, and the heat treatment of each portion 141, 142 may be performed in this state.

[0053] Alternatively, the magnetic flux density may be made different between the first portion 141 and the second portion 142 by cold or hot working the annular member 102. In this case, the magnetic flux density of the second portion 142, which is radially outward of the field winding 70, may be reduced by performing cold or hot working more times than that of the first portion 141 or by increasing the processing stress.

[0054] The circular member 102 may also have a configuration shown in Fig. 13. In the configuration shown in Fig. 13, high magnetic portions A1 and low magnetic portions A2 are alternately provided at predetermined intervals in the wire 131 constituting the circular member 102, and the wire 131 is then wound around the outer periphery of the main pole 62 of the rotor core 61 and the field winding 70. In this case, the wire 131 has high magnetic portions A1, which are relatively highly magnetic, and low magnetic portions A2, which are relatively low magnetic, at intervals corresponding to the circumferential pole pitch of the rotor 60. When the wire 131 is wound, the high magnetic portions A1 of the wire 131 form a high magnetic flux density portion 151 in the first portion 141, and the low magnetic portions A2 form a low magnetic flux density portion 152 in the second portion 142.

[0055] In the circular member 102, there is a concern about magnetic flux leakage in a portion of the second portion 142 that is radially outward of the field winding 70 and that is circumferentially near the main pole portion 62. In other words, in the circular member 102, both circumferential end portions of the second portion 142 are regions where magnetic flux leakage occurs. In this case, in a configuration in which the magnetic flux densities of the portions 141, 142 of the circular member 102 are different from each other, if, for example, the set range of the high magnetic portion in the first portion 141 is shifted in the circumferential direction, it is conceivable that unintended magnetic flux leakage will occur in both circumferential end portions of the second portion 142.

[0056] 14 , in the annular member 102, the high magnetic flux density portion 151 may be defined in a circumferentially narrower range than the first portion 141 located radially outward from the main pole portion 62. In this case, the magnetic flux density is relatively lower in the first portion 141 at a portion near the boundary between the first portion 141 and the circumferentially adjacent second portion 142 than in the other portions near the boundary. Furthermore, the low magnetic flux density portion 152 is defined in a circumferentially wider range than the second portion 142 located radially outward from the field winding 70. In the configuration of FIG. 14 , in the annular member 102, the boundary position between the high magnetic flux density portion 151 and the low magnetic flux density portion 152 does not necessarily coincide with the boundary position between the first portion 141 and the second portion 142.

[0057] The low magnetic flux density portion 152 is a circumferentially wider region than the second portion 142, and the proportion of the region with relatively low magnetic flux density over the entire circumferential direction of the circular member 102 is greater than the proportion of the second portion 142. Therefore, the circular member 102 is configured such that suppression of magnetic flux leakage is prioritized near the boundary position between the first portion 141 and the second portion 142. In this case, even if the high magnetic flux density portion 151 is unintentionally shifted circumferentially in the circular member 102, magnetic flux leakage in the second portion 142 is suppressed.

[0058] 13 , in a configuration in which wire 131 having high magnetic portions A1 and low magnetic portions A2 is wound, a shift in the magnetic flux density switching position may occur due to a shift in the winding position of wire 131. However, by defining high magnetic flux density portion 151 in a range narrower in the circumferential direction than first portion 141 as described above, magnetic flux leakage in second portion 142 is suppressed.

[0059] In the annular member 102, as a configuration in which the magnetic flux density is made different between the first portion 141 and the second portion 142, a configuration in which the wire 131 is wound in a state in which a tensile stress is applied, and the tensile stress is made different between the first portion 141 and the second portion 142 may be employed. In this case, the magnetic flux density is made smaller in the second portion 142 by making the tensile stress in the winding direction of the wire 131 larger than in the first portion 141.

[0060] 15 , a spacer 161 is interposed between circumferentially adjacent main pole portions 62 and between the winding unit 110 and the annular member 102. In this case, the interposition of the spacer 161 makes it possible to increase the tensile stress in the winding direction of the wire 131 in the second portion 142 compared to the first portion 141.

[0061] During the manufacture of the rotor 60, the wire 131 is wound around the main pole 62 of the rotor core 61 and the field winding 70 while applying a predetermined initial tensile stress without the spacer 161. The spacer 161 is then pressed axially between the winding unit 110 and the annular member 102 in the radial direction. The outer peripheral surface of the main pole 62 is arc-shaped with its center at the rotor axis. The spacer 161 has a cross-sectional shape consisting of an arc with the same diameter as the outer peripheral surface of the main pole 62 and a chord linearly connecting both ends of the arc. The axial length of the spacer 161 is the same as that of the rotor core 61.

[0062] By forcing the spacer 161 between the winding unit 110 and the circular member 102, the circular member 102 expands radially outward by the amount of the spacer. This results in a configuration in which the tensile stress of the wire 131 is greater in the second portion 142 than in the first portion 141. In this case, the circular member 102 is formed into a circular shape by the outer peripheral surfaces of the main pole portion 62 and the spacer 161.

[0063] When winding the wire 131 around the main pole 62 of the rotor core 61 and the outer periphery of the field winding 70, it is preferable that the radially outer outer surface of the main pole 62 and the wire 131 are joined with an adhesive or the like, and that the multiple wound wires 131 are joined together with an adhesive or the like.

[0064] Alternatively, a foamable resin may be interposed between the winding unit 110 and the annular member 102, and the foamable resin may be foamed and hardened by an external stimulus such as heat or ultraviolet light, thereby increasing the tensile stress. The foamable resin may be a thermosetting foamable resin, for example, made of epoxy resin, which is a thermosetting resin, with beads dispersed therein that foam in response to a thermal stimulus.

[0065] According to the present embodiment described above in detail, the following excellent effects can be obtained.

[0066] In the rotating electric machine 40, the main pole portions 62 of the rotor core 61 and the field winding 70 are surrounded by a metallic annular member 102. This suppresses displacement and deformation of the field winding 70 even when centrifugal force acts on the field winding 70 during rotor rotation. Furthermore, in the annular member 102, a first portion 141 located radially outward of the main pole portions 62 and a second portion 142 located radially outward of the field winding 70 have different magnetic flux densities, with the first portion 141 having a higher magnetic flux density than the second portion 142. This allows for proper transmission of magnetic flux between the rotor 60 and the stator 50. As a result, the motor torque of the rotating electric machine 40 can be improved, resulting in improved motor performance. Furthermore, the rotating electric machine 40 can be made smaller and have a higher torque.

[0067] In the circular member 102, there is a concern about magnetic flux leakage in a portion of the second portion 142 that is radially outward of the field winding 70 and that is circumferentially near the main pole portion 62. Furthermore, if a shift occurs in the magnetic flux density switching position in the circular member 102, it is thought that the effect of suppressing magnetic flux leakage in the second portion 142 will be reduced. In consideration of this, the circular member 102 is configured such that the high magnetic flux density portion 151 (a range with relatively high magnetic flux density) is defined in a circumferentially narrower range than the first portion 141. In this case, even if a shift occurs in the magnetic flux density switching position in the circular member 102, magnetic flux leakage can be suitably reduced.

[0068] The annular member 102 is formed by winding the wire 131, with tensile stress applied, around the outer periphery of each main pole portion 62 and the field winding 70. In particular, the second portion 142 is configured to have a larger tensile stress in the winding direction of the wire 131 than the first portion 141. In this case, the difference in tensile stress in the wire 131 can cause the magnetic flux density to vary locally, thereby improving motor performance.

[0069] By interposing spacers 161 between circumferentially adjacent main pole portions 62 and between the winding unit 110 and the annular member 102, the tensile stress of the wire material 131 is made larger in the second portion 142 than in the first portion 141. In this case, after the winding units 110 of each magnetic pole are assembled to the rotor core 61, the tensile stress of the wire material 131 can be suitably adjusted by press-fitting the spacers 161.

[0070] Wire 131 having high magnetic portions A1 and low magnetic portions A2 spaced apart in the circumferential direction according to the magnetic pole pitch is used, with the high magnetic portions A1 of wire 131 constituting first portions 141 and the low magnetic portions A2 constituting second portions 142. In this case, by winding wire 131 around each main pole portion 62 of rotor core 61 and the outer periphery of field winding 70, first portions 141 and second portions 142 can be easily provided for each magnetic pole.

[0071] (Other Embodiments) The above embodiment may be modified as follows, for example.

[0072] 16, the annular member 102 is formed by joining together a plurality of circumferentially divided arc members 171. Fig. 16(a) shows the state after the arc members 171 have been assembled to the rotor core 61 and the field winding 70, and Fig. 16(b) shows the state before the arc members 171 have been assembled.

[0073] Each arc member 171 has high magnetic portions 172 with relatively high magnetic properties and low magnetic portions 173 with relatively low magnetic properties, spaced at intervals corresponding to the circumferential magnetic pole pitch. When each arc member 171 is attached, the high magnetic portions 172 of each arc member 171 form the first portion 141, and the low magnetic portions 173 form the second portion 142. The arc members 171 are joined to each other at their circumferential joining surfaces by adhesive bonding, welding, melt-adhesion, or the like. Note that each arc member 171 may be attached to the main pole 62 by adhesive bonding, or by fastening with fasteners such as screws.

[0074] In the circular member 102, the boundary position between the high magnetic portion 172 and the low magnetic portion 173 may or may not coincide with the boundary position between the first portion 141 and the second portion 142. If they do not coincide, the high magnetic portion 172 may be a narrower region in the circumferential direction than the first portion 141, and the low magnetic portion 173 may be a wider region in the circumferential direction than the second portion 142. The number of divisions in the circumferential direction of the circular member 102 may be other than two, and may be, for example, divided into three or four parts in the circumferential direction.

[0075] In the above configuration, by assembling a plurality of arc members 171 on the outer periphery of each main pole portion 62 of the rotor core 61 and the field winding 70, the first portion 141 and the second portion 142 can be easily provided for each magnetic pole.

[0076] The annular member 102 may be formed in advance into an annular shape and then fitted axially around the outer periphery of each main pole portion 62 of the rotor core 61 and the field winding 70 .

[0077] In the stator 50, the stator core may not be provided with teeth.

[0078] The rotating electric machine is not limited to a rotating electric machine used as an in-vehicle main engine, but may be, for example, a rotating electric machine used as an ISG (Integrated Starter Generator) that is both a motor and a generator.

[0079] The moving body on which the rotating electric machine system is mounted is not limited to a vehicle, but may be, for example, an aircraft or a ship. Furthermore, the rotating electric machine system is not limited to a system mounted on a moving body, but may be a stationary system.

[0080] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and equivalent modifications. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

Claims

1. A wound field rotor (60) comprising: a rotor core (61) having a plurality of main pole portions (62) provided for each of the magnetic poles arranged in the circumferential direction; a field winding (70) provided in a state where it is wrapped around each of the main pole portions; and a metallic circular member (102) provided so as to surround each of the main pole portions and the field winding from the radial outside, the wound field rotor (60) being disposed radially opposite a stator (50) in a rotating electric machine (40), wherein the circular member has, in the circumferential direction, a first portion (141) that is radially outside the main pole portions and a second portion (142) that is radially outside the field winding, the first portion and the second portion having different magnetic flux densities, the first portion having a relatively higher magnetic flux density than the second portion.

2. A wound field rotor according to claim 1, wherein the area of ​​said annular member where the magnetic flux density is relatively high is defined as an area narrower in the circumferential direction than said first portion.

3. A wound field rotor as claimed in claim 1 or 2, wherein the annular member is formed by winding metal wire (131) around the outer periphery of each of the main poles and the field winding while a tensile stress is applied thereto, and the tensile stress in the winding direction of the wire is greater in the second portion than in the first portion.

4. A wound field rotor as set forth in claim 3, wherein the field winding has a plurality of pole coils (110) each provided for each of the main pole portions and wound with conductive wire, and spacers (161) are interposed between the circumferentially adjacent main pole portions and between the pole coils and the annular member, so that the tensile stress in the winding direction of the wire is greater in the second portion than in the first portion.

5. A wound field rotor as claimed in claim 1 or 2, wherein the annular member is formed by winding a metal wire (131) around the outer periphery of each of the main poles and the field winding, the wire having high magnetic portions (A1) with relatively high magnetic properties and low magnetic portions (A2) with relatively low magnetic properties at intervals corresponding to the circumferential pole pitch, and wherein, when the wire is wound, the high magnetic portions of the wire constitute the first portion and the low magnetic portions constitute the second portion.

6. A wound field rotor as claimed in claim 1 or 2, wherein the annular member is formed by joining together a plurality of circumferentially divided arc members (171), each of which has high magnetic portions (172) with relatively high magnetic properties and low magnetic portions (173) with relatively low magnetic properties at intervals corresponding to the circumferential magnetic pole pitch, and wherein, when the arc members are attached, the high magnetic portions of each arc member constitute the first portion, and the low magnetic portions constitute the second portion.

Images