Rotary electric machine

Abstract

To provide a rotary electric machine that is light-weight, and capable of improving energy efficiency at high rotational speeds.SOLUTION: A rotary electric machine according to an embodiment includes a rotor and a stator. The rotor is a rotor capable of rotating about a central axis. The stator surrounds the rotor from one side of the radial direction. The stator has a back yoke, a coil portion, and a plurality of partition portions. The back yoke is annular about the central axis. The coil portion is disposed on the other side of the radial direction of the back yoke. The plurality of partition portions partition a winding range in which the coil portion is disposed in the circumferential direction. The partition portion has a magnetic body portion formed of a magnetic body. The circumferential dimension of the magnetic body section is less than the circumferential dimension of the winding range. The radial dimension of the magnetic body portion is half the radial dimension of the coil portion or more.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] An embodiment of the present invention relates to a rotating electric machine. [Background technology]

[0002] In recent years, with the growing awareness of environmental considerations, aircraft in which a propulsion fan is driven by a rotating electric machine are being developed. Rotating electric machines for aircraft are required to be lightweight and capable of high-speed rotation. As a rotating electric machine for ensuring light weight, a machine in which a stator is formed by combining a coil and an annular back yoke is known. In such a rotating electric machine, the magnetic flux passes through the conductor of the coil, so copper loss is likely to occur. In particular, in a rotating electric machine that rotates at high speed, there is a problem that the copper loss becomes significant and the energy efficiency of the rotating electric machine decreases. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP2020-018132 Public Relations Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a rotating electric machine that is lightweight and capable of improving energy efficiency during high speed rotation. [Means for solving the problem]

[0005] A rotating electric machine according to an embodiment has a rotor and a stator. The rotor is rotatable about a central axis. The stator surrounds the rotor from one radial side. The stator has a back yoke, a coil portion, and multiple partition portions. The back yoke is annular about the central axis. The coil portion is disposed on the other radial side of the back yoke. The multiple partition portions define a winding range in the circumferential direction in which the coil portion is disposed. The partition portion has a magnetic material portion made of a magnetic material. A ratio of a circumferential dimension of the magnetic material portion to a circumferential dimension of the winding range is less than 1. A ratio of a radial dimension of the magnetic material portion to a radial dimension of the winding range is 1 / 2 or more. [Brief description of the drawings]

[0006] [Figure 1] 1 is a cross-sectional view of a rotating electric machine according to a first embodiment. [Diagram 2] 1 is a perspective view of a magnet included in a rotating electric machine according to a first embodiment. [Diagram 3] 1 is a schematic cross-sectional view of a stator included in a rotating electric machine according to a first embodiment. [Figure 4] 5 is a graph showing the relationship between the ratio of the radial dimension of the magnetic body portion to the radial dimension of the winding range and the driving efficiency in the rotating electric machine according to the first embodiment. [Diagram 5] FIG. 6 is a schematic cross-sectional view of a stator according to a second embodiment. [Figure 6] FIG. 13 is a perspective view of a magnet according to a modified example. [Figure 7] FIG. 1 is a schematic diagram showing an example configuration of an aircraft. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Hereinafter, a rotating electric machine according to an embodiment will be described with reference to the drawings. The design of a rotating electric machine can be changed as appropriate according to specifications, etc. Therefore, the shape, etc. of each member included in the rotating electric machine can be changed arbitrarily, and the shapes, numbers, etc. in the drawings are merely examples.

[0008] (First embodiment) FIG. 1 is a cross-sectional view of a rotating electric machine 1 according to the present embodiment. As shown in FIG. 1, the rotating electric machine 1 has a rotor 20 and a stator 30. In the following description, a direction parallel to the central axis J is simply called the "axial direction", a radial direction centered on the central axis J is simply called the "radial direction", and a circumferential direction centered on the central axis J is simply called the "circumferential direction". Furthermore, a radial direction away from the central axis J may be called the "radial outer side" or "one radial side", and a radial direction approaching the central axis J may be called the "radial inner side" or "other radial side". In addition, a circumferential direction θ around the central axis J is illustrated in each drawing as necessary. In each drawing, a direction in which an arrow of the circumferential direction θ points may be called the "one circumferential side (+θ)", and an opposite direction may be called the "other circumferential side (-θ)".

[0009] The rotating electric machine 1 according to this embodiment is an inner rotor type rotating electric machine in which the rotor 20 is disposed radially inside the stator 30. However, the rotating electric machine may be an outer rotor type rotating electric machine in which the rotor is disposed radially outside the stator. In this case, the configuration is such that one radial side and the other radial side are reversed in each part of the rotor.

[0010] The rotor 20 is rotatable about a central axis J. The rotor 20 includes a shaft 21 having a central axis J, a hub member 22, a rotor core 27, a magnet unit 25, and a cover 26.

[0011] The shaft 21 extends along the central axis J. The shaft 21 included in the rotating electric machine 1 according to this embodiment is, for example, cylindrical and extending in the axial direction. The shaft 21 is supported by a bearing (not shown) so as to be rotatable about the central axis J.

[0012] The hub member 22 is, for example, cylindrical with a sufficient thickness in the radial direction. The hub member 22 can be fixed to the outer circumferential surface of the shaft 21. In addition, the rotor core 27 can be fixed to the outer circumferential surface of the hub member 22. Note that the hub member 22 may be provided with a plurality of holes penetrating in the axial direction.

[0013] The rotor core 27 is made of a magnetic material. The rotor core 27 is, for example, a laminated steel plate formed by stacking a plurality of electromagnetic steel plates in the axial direction. The rotor core 27 provided in the rotating electric machine 1 according to this embodiment is, for example, cylindrical. The magnet unit 25 is disposed on the outer circumferential surface of the rotor core 27.

[0014] The magnet unit 25 has, for example, a circular ring shape. The magnet unit 25 can be fixed to the outer circumferential surface of the rotor core 27 by a joining means such as adhesive. The rotor 20 provided in the rotating electric machine 1 according to this embodiment is a surface magnet type in which the magnet unit 25 directly faces the stator 30 magnetically. However, the configuration of the rotor 20 is not limited to this embodiment, and may be, for example, an embedded magnet type.

[0015] The magnet unit 25 has a plurality of first magnets 25s and a plurality of second magnets 25n. The first magnets 25s and the second magnets 25n are arranged alternately in the circumferential direction. The magnetization directions of the first magnets 25s and the second magnets 25n are opposite to each other in the radial direction. The first magnets 25s are magnets that form an S pole on the radially outer side, and the second magnets 25n are magnets that form an N pole on the radially outer side. Hereinafter, when the first magnets 25s and the second magnets 25n are not distinguished from each other, they are simply referred to as magnets 25m. That is, the magnet unit 25 has a plurality of magnets 25m whose magnetization directions alternate in the circumferential direction.

[0016] The magnet 25m provided in the rotating electric machine 1 according to this embodiment extends, for example, in an arc shape centered on the central axis J when viewed in the axial direction. The magnet 25m is plate-shaped with its thickness direction in the radial direction. An inner surface of the magnet 25m facing radially inward is adhesively fixed to an outer surface of the rotor core 27. An outer surface of the magnet 25m facing radially outward is covered by a cylindrical cover 26. The cover 26 surrounds the magnet unit 25 and prevents the multiple magnets 25m from detaching from the rotor core 27. The cover 26 is made of a material that is unlikely to affect the magnetic force of the magnet unit 25.

[0017] FIG. 2 is a perspective view of a magnet 25m included in the rotating electric machine according to this embodiment. As shown in FIG. 2, the magnet 25m included in the rotating electric machine 1 according to this embodiment may be a split magnet. In the case of a split magnet, the magnet 25m has a plurality of element magnets 25e stacked in the axial direction. The plurality of element magnets 25e are, for example, sintered magnets. In the example shown in FIG. 2, the element magnets 25e aligned in the axial direction are joined to each other via adhesive layers 25b. The magnetization directions of the stacked element magnets 25e are radial and coincide with each other. In the example shown in FIG. 2, the plurality of element magnets 25e are magnetized after being joined to each other via adhesive layers 25b.

[0018] The magnet 25m provided in the rotating electric machine 1 according to this embodiment is formed by joining a plurality of element magnets 25e. Therefore, compared to a case where the magnet is formed of a single sintered magnet, the value of the eddy current flowing through each element magnet 25e can be made smaller, and the eddy current loss generated in the magnet 25m as a whole can be reduced. This suppresses heat generation in the magnet 25m caused by eddy currents generated in the magnet 25m, reduces a decrease in the magnetic force of the magnet 25m, and improves the torque performance of the rotating electric machine 1.

[0019] In this embodiment, the adhesive layer 25b that bonds the element magnets 25e together is preferably made of an insulating material. In this case, it is possible to prevent current from flowing between the bonded element magnets 25e, and to effectively suppress eddy current loss in the magnet 25m. In addition, the element magnets 25e may be insulated from each other by, for example, forming an insulating coating on the surface of the element magnets 25e.

[0020] In this embodiment, the element magnet 25e is preferably made of a samarium-cobalt magnet. That is, the magnet 25m of the rotating electric machine 1 according to this embodiment is preferably a samarium-cobalt magnet. The samarium-cobalt magnet has superior heat resistance compared to other common rare earth magnets such as neodymium magnets, and is known to maintain high magnetic properties even at high temperatures of 150°C or higher. When the rotating electric machine 1 according to this embodiment is mounted on an aircraft 90, it is required to be small and lightweight. For this reason, it is difficult to adopt a cooling structure and a heat dissipation structure for the rotating electric machine 1. According to this embodiment, by adopting a samarium-cobalt magnet as the magnet 25m, it is possible to configure a rotating electric machine 1 that exhibits sufficient torque performance even when the magnet 25m becomes hot. As a result, the cooling structure and the heat dissipation structure of the rotating electric machine 1 can be simplified.

[0021] 1, a stator 30 included in a rotary electric machine 1 according to this embodiment surrounds a rotor 20 from the radial outside. The stator 30 has a back yoke 31, a guide member 32, and a coil portion .

[0022] The back yoke 31 is, for example, annular about the central axis J. The back yoke 31 is made of a magnetic material. The back yoke 31 is, for example, a laminated steel plate formed by stacking a plurality of electromagnetic steel plates in the axial direction. A magnetic circuit for rotating the rotor 20 passes through the back yoke 31. The inner peripheral surface of the back yoke 31 provided in the rotating electric machine 1 according to this embodiment is a cylindrical surface centered on the central axis J and has no irregularities. In other words, the back yoke 31 provided in the rotating electric machine 1 according to this embodiment does not have a typical teeth structure.

[0023] The guide member 32 has, for example, a resin portion 32c made of insulating resin and a plurality of magnetic material portions 33 made of magnetic material. The guide member 32 can be manufactured by, for example, insert molding in which the magnetic material portions 33 are embedded in the resin portions 32c.

[0024] The guide member 32 has, for example, an annular portion 32a and a plurality of partition portions 32b. The annular portion 32a is, for example, cylindrical and centered on a central axis J. The outer circumferential surface of the annular portion 32a can be fixed to the inner circumferential surface of the back yoke 31 by a joining means such as adhesive. The entire annular portion 32a is constituted by a resin portion 32c. The annular portion 32a is disposed between the back yoke 31 and the coil portion 40. The annular portion 32a provides insulation between the back yoke 31 and the coil portion 40.

[0025] The partitions 32b protrude radially inward from the inner circumferential surface 32e of the annular portion 32a. The partitions 32b have a rib shape that protrudes radially and extends along the axial direction. The partitions 32b are arranged at equal intervals in the circumferential direction. A winding range C in which the coil portion 40 is arranged is provided between the partitions 32b adjacent to each other in the circumferential direction. That is, the partitions 32b partition the winding range C. The stator 30 provided in the rotating electric machine 1 according to this embodiment is provided with the same number of winding ranges C as the partitions 32b. The winding range C provided in the rotating electric machine 1 according to this embodiment forms a flattened rectangular shape that is larger in the circumferential direction than in the radial direction. This allows the coil portion 40 arranged in the winding range C to be thinned in the radial direction, and as a result, the rotating electric machine 1 can be made smaller in the radial direction. The configurations of the partitions 32b and the winding range C are not limited to this embodiment.

[0026] In this specification, the "winding range C" refers to the range in which the coil portion 40 can be arranged. As described below, since the coil portion 40 is composed of a plurality of wires 42e, it is difficult to determine the shape of the coil portion 40. The winding range C is an area in which the coil portion 40, which has no fixed shape, can be arranged, and is an area defined as described below.

[0027] In this embodiment, the winding range C is a range between adjacent partitions 32b in the circumferential direction. Therefore, the winding range C is provided between a surface 32g facing the other circumferential side (-θ) of the partition 32b located on one circumferential side (+θ) of the partition 32b adjacent to each other in the circumferential direction and a surface 32h facing the one circumferential side (+θ) of the partition 32b located on the other circumferential side (-θ) of the partition 32b.

[0028] In this embodiment, the winding range C is a range between the rotor 20 and the annular portion 32a in the radial direction. In addition, an air gap G is provided on the radial outside of the rotor 20 to avoid contact with the stator 30. For this reason, the winding range C is provided between a virtual circle VC that is offset radially outward from the outer circumferential surface 20f of the rotor 20 by the size of the air gap G, and the inner circumferential surface 32e of the annular portion 32a. The virtual circle VC passes through the inner end of the coil portion 40 on the radial inside. Therefore, the radial dimension of the winding range C can be the distance from the inner circumferential surface 32e of the annular portion 32a to the radially inner end of the coil portion 40.

[0029] The magnetic body part 33 is embedded in the resin part 32c of the partition part 32b. That is, the partition part 32b provided in the rotating electric machine 1 according to this embodiment has the magnetic body part 33 and the resin part 32c covering the outer surface of the magnetic body part 33. The resin part 32c covering the magnetic body part 33 insulates between the magnetic body part 33 and the coil part 40. In this embodiment, a part of the resin part 32c is interposed between the magnetic body part 33 and the back yoke 31 to suppress contact between the magnetic body part 33 and the back yoke 31. However, the magnetic body part 33 may be in contact with the inner peripheral surface of the back yoke 31 at an end surface facing radially outward, or the magnetic body part 33 and the back yoke 31 may be formed integrally.

[0030] The magnetic body part 33 included in the rotating electric machine 1 according to this embodiment has, for example, a rectangular column shape extending along the axial direction. The magnetic body part 33 included in the rotating electric machine 1 according to this embodiment has a rectangular shape when viewed from the axial direction. The magnetic body part 33 is, for example, a laminated steel plate formed by laminating a plurality of electromagnetic steel plates in the axial direction. The magnetic body part 33 passes magnetic flux intensively between the winding ranges C arranged in the circumferential direction. The action of the magnetic body part 33 will be described in detail later. The shape of the magnetic body part 33 is not limited to this embodiment. The magnetic body part 33 may have any shape, and may have, for example, a shape in which the end face in the circumferential direction or the radial direction is curved. In addition, the multiple magnetic body parts 33 may have different shapes from each other. That is, the magnetic body part 33 may have an indefinite shape.

[0031] The coil section 40 is disposed on the radial inside of the back yoke 31 via the annular portion 32a. The coil section 40 has a plurality of (three in this embodiment) phase coils 41. Here, in order to illustrate and explain a three-phase AC rotating electric machine, the number of phase coils 41 is assumed to be three, but the number of phase coils 41 is not limited to this embodiment. The coil section 40 in FIG. 1 is configured by distributed winding in which the phase coils 41 of different phases are shifted in the circumferential direction and overlap in the radial direction. AC currents of different phases flow through each of the phase coils 41. In the example shown in FIG. 1, AC currents with a phase shift of 120° flow through the three phase coils 41. The phase difference of the AC currents flowing through the phase coils 41 is appropriately changed depending on the number of phase coils 41. In the following description, when the plurality of phase coils 41 are to be distinguished from one another, they are called a U-phase coil 41U, a V-phase coil 41V, and a W-phase coil 41W.

[0032] The U-phase coil 41U, the V-phase coil 41V, and the W-phase coil 41W are arranged in different winding ranges C. That is, only phase coils 41 of the same phase are arranged in one winding range C. In this embodiment, the U-phase coil 41U, the V-phase coil 41V, and the W-phase coil 41W are arranged in this order in the multiple winding ranges C arranged on one circumferential side, and then the U-phase coil 41U, the V-phase coil 41V, and the W-phase coil 41W are arranged in this order again. Therefore, the phase coils 41 of the same phase are arranged in winding ranges C that are three adjacent to each other in the circumferential direction.

[0033] 1 is located radially inward relative to the end face of the partition 32b facing radially inward. According to the rotating electric machine 1 of this embodiment, the partition 32b is made smaller in the radial direction, and the weight of the rotating electric machine 1 can be reduced. The end face of the partition 32b facing radially inward may be located radially inward relative to the radially inward end of the coil unit 40. In this case, the radially inward end of the stator 30 can be the end face of the partition 32b, making it easier to manage the dimensions of the air gap G.

[0034] Fig. 3 is a schematic cross-sectional view of a stator 30 included in the rotary electric machine 1 according to this embodiment. In Fig. 3, the circumferential direction is shown as a straight line.

[0035] As shown in FIG. 3, the phase coil 41 includes a plurality of wire bundles 42. In the stator 30 included in the rotating electric machine 1 according to this embodiment, a plurality of wire bundles 42 are arranged in one winding range C. Each wire bundle 42 is formed by bundling a plurality of wires 42e. The wires 42e may be either round or rectangular, and may have an irregular cross section. The wire bundle 42 is wound in a loop shape a plurality of times between three adjacent winding ranges C in the circumferential direction to form the phase coil 41. The number of wire bundles 42 arranged in the winding range C can be arbitrarily changed depending on the coil design.

[0036] In this embodiment, the radially inner region of the back yoke 31 is divided into a plurality of winding ranges C by the partitioning portion 32b. According to the rotating electric machine 1 of this embodiment, it is possible to easily position each phase coil 41 of the coil section 40 in the circumferential direction, and the assembly process of the stator 30 can be simplified. In addition, the partitioning portion 32b suppresses the coil section 40 from being displaced in the circumferential direction due to the magnetic force applied to the coil section 40 when the rotating electric machine 1 is driven. In addition, in this embodiment, the partitioning portion 32b is disposed between the phase coils 41 of different phases, thereby insulating the phase coils 41 of different phases from each other. This suppresses discharge between the phase coils 41 of different phases, and a highly reliable rotating electric machine 1 can be configured.

[0037] Here, of the wire bundle 42 wound in a loop shape, a portion arranged in one winding range C is referred to as a first portion 42a, and a portion arranged in a winding range C three winding ranges away from the aforementioned winding range C is referred to as a second portion 42b. The first portion 42a and the second portion 42b are connected via a crossover portion 42d of the wire bundle 42. The crossover portion 42d constitutes coil ends on one axial side and the other axial side of the back yoke 31, respectively. The wire bundle 42 extends from one axial side to the other axial side in the first portion 42a in the winding range C, extends in the circumferential direction in the crossover portion 42d located on the other axial side of the back yoke 31, and extends from the other axial side to one axial side in the second portion 42b in the winding range C. That is, the direction of the current flowing through the wire bundle 42 is opposite to that in the axial direction in the first portion 42a and the second portion 42b.

[0038] Each of the wires 42e is formed by applying an insulating coating such as enamel coating to the surface of a wire material having excellent electrical conductivity, such as a copper alloy. The wires 42e may be wire material made of a superconductor. The multiple wires 42e constituting one wire bundle 42 are connected in parallel to each other. The number of wires 42e included in the wire bundle 42 can be arbitrarily changed depending on the coil design.

[0039] Of the multiple wires 42e included in one wire bundle 42 provided in the rotating electric machine 1 according to this embodiment, the multiple wires 42e in the first portion 42a and the multiple wires 42e in the second portion 42b are preferably arranged in mirror symmetry with each other. Therefore, for example, the wire 42e arranged furthest on one circumferential side (+θ) in the first portion 42a is connected to the wire 42e arranged furthest on the other circumferential side (-θ) in the second portion 42b via a crossover portion 42d. Note that "arranged in mirror symmetry" means that the wire bundle 42 is wound so that the arrangement of the wires 42e is reversed relative to one another in the circumferential direction to form the coil portion 40. Therefore, a structure in which the wires 42e are slightly out of alignment or the shape of each wire bundle 42 is slightly out of alignment during or after winding the wire bundle 42 is also included in the structure in which the wires are arranged in mirror symmetry.

[0040] A conventional stator includes a stator core having a back yoke and a plurality of teeth extending radially inward from the back yoke, and a coil portion wound around the teeth. In such a conventional stator, the magnetic flux generated when the rotating electric machine is driven flows concentratedly in the teeth, so that the number of magnetic fluxes passing through the coil wire constituting the coil can be reduced, and copper loss in the coil portion can be reduced. However, on the other hand, in the stator of the conventional structure, the cross-sectional area of ​​the teeth is sufficiently secured in order to suppress magnetic saturation in the teeth, which makes the rotating electric machine large and heavy.

[0041] In contrast, the stator 30 of the rotating electric machine 1 according to this embodiment employs a teethless structure (or a slotless structure) that does not have teeth. Therefore, according to this embodiment, the weight of the rotating electric machine 1 can be reduced. Furthermore, since the stator 30 of the rotating electric machine 1 according to this embodiment does not have teeth, the winding range C provided radially inside the back yoke 31 can be secured wide in the circumferential direction. As a result, the coil section 40 arranged in the winding range C can be arranged wide in the circumferential direction, and the stator 30 can be made small in the radial direction while securing a sufficient cross-sectional area of ​​the coil section 40. That is, according to this embodiment, it is possible to configure a small and lightweight rotating electric machine 1.

[0042] In a stator 30 having a teethless structure such as the rotating electric machine 1 according to this embodiment, since magnetic flux passes through the coil section 40, an electromotive force is generated in the coil section 40, and copper loss is likely to occur in the coil section 40. In particular, the rotating electric machine 1 according to this embodiment is used to rotate a propulsion fan 93 of an aircraft 90, or to generate power using a jet engine 91 of the aircraft 90. For this reason, it is expected that the rotating electric machine 1 will be used at a high rotation speed of, for example, several thousand rpm or more. Thus, in a rotating electric machine 1 that steadily rotates at a high speed, copper loss occurring in the coil section 40 is likely to become significant.

[0043] In contrast, according to the rotating electric machine 1 of this embodiment, the magnetic body portion 33 is provided between the winding ranges C. As a result, when the rotating electric machine 1 is driven, a part of the magnetic flux formed in the radial direction between the rotor 20 and the back yoke 31 can be concentrated in the magnetic body portion 33, and the number of magnetic fluxes passing through the coil portion 40 can be reduced. This can reduce copper loss occurring in the coil portion 40. Note that, unlike teeth, the magnetic body portion 33 provided in the rotating electric machine 1 of this embodiment becomes magnetically saturated when the rotating electric machine 1 is driven. This is because the circumferential dimension Wst of the magnetic body portion 33 provided in the rotating electric machine 1 of this embodiment is limited, thereby ensuring a large circumferential dimension Wc of the winding range C. However, even if the magnetic body portion 33 becomes magnetically saturated when driven, the influence is limited to a narrow range when viewed from the entire rotating electric machine 1, so that a highly efficient rotating electric machine 1 can be configured while taking advantage of the advantages of the teethless structure.

[0044] In the conventional structure, the teeth serve as the main magnetic path of the stator, and therefore magnetic saturation leads to a decrease in the torque of the rotating electric machine, and therefore a decrease in efficiency. In contrast, the magnetic body part 33 of the rotating electric machine 1 according to this embodiment has a main role of reducing the imbalance of the magnetic flux passing through the coil part 40 and the interlinking magnetic flux between different wires, and does not serve as the main magnetic path. Therefore, in the rotating electric machine 1 of this embodiment, even if the magnetic body part 33 becomes magnetically saturated, the torque of the rotating electric machine 1 is not significantly affected, while the copper loss generated in the coil part 40 is reduced. As a result, the torque of the rotating electric machine 1 can be maintained while improving the driving efficiency.

[0045] Copper loss occurring in the coil section 40 is classified into those caused by DC resistance, those caused by the proximity effect, and those caused by circulating current. Copper loss due to the proximity effect is energy loss that occurs when the magnetic flux density interlinking with each strand 42e of the coil section 40 changes over time, causing eddy currents to flow through the strands 42e and dissipate as heat. In the rotating electric machine 1 according to this embodiment, the rotor 20 is a surface magnet type, and the magnets 25m directly face the stator 30 magnetically. Therefore, as the rotor 20 rotates, the magnetic flux density interlinking with the strands 42e is likely to change suddenly, and the eddy currents flowing on the surface of the strands 42e are likely to increase. According to this embodiment, the partition section 32b has the magnetic body section 33, so that the number of magnetic fluxes passing through the strands 42e can be suppressed, and copper loss due to the proximity effect can be reduced.

[0046] Copper loss due to circulating current is an energy loss that occurs when the density of magnetic flux linking between the wires 42e included in the wire bundle 42 of the coil portion 40 changes over time, causing a current to flow between the wires 42e and be released as heat. According to this embodiment, the magnetic flux when the rotating electric machine 1 is driven is concentrated in the magnetic body portion 33. This makes it difficult for the number of magnetic fluxes linking with different wires 42e to be distributed between the first portion 42a and the second portion 42b of the wire bundle 42. As a result, it becomes difficult for differences in electromotive force to occur between the wires 42e, making it possible to suppress potential differences between the wires 42e and suppressing circulating current.

[0047] As described above, in the wire bundle 42 included in the rotating electric machine 1 according to this embodiment, the arrangement of the plurality of wires 42e in the first portion 42a and the arrangement of the plurality of wires 42e in the second portion 42b are mirror symmetric. This makes it possible to reduce the change over time in the difference in the number of magnetic fluxes linking different wires 42e, and further reduce the difference in electromotive force generated between the wires 42e. In other words, according to this embodiment, by making the arrangement of the wires 42e in the first portion 42a and the arrangement of the wires 42e in the second portion 42b mirror symmetric, it is possible to further suppress copper loss due to circulating current.

[0048] In the stator 30 included in the rotating electric machine 1 according to this embodiment, the ratio (Wst / Wc) of the circumferential dimension Wst of the magnetic material portion 33 to the circumferential dimension Wc of the winding range C is preferably less than 1, and more preferably less than 1 / 2. In this specification, the "circumferential dimension" means the linear distance in a direction perpendicular to the radial direction as viewed from the axial direction, and does not mean the length of an arc extending in the circumferential direction.

[0049] Here, the circumferential dimension Wst of the magnetic body part 33 is the maximum distance dimension between the end 33a on one circumferential side (+θ) and the end 33b on the other circumferential side (-θ) of one magnetic body part 33. Since the magnetic body part 33 provided in the rotating electric machine 1 according to the present embodiment is rectangular when viewed from the axial direction, in FIG. 3, the circumferential dimension Wst of the magnetic body part 33 is constant at any radial position of the magnetic body part 33. Also, for example, when the magnetic body part is triangular or trapezoidal tapered toward the radially inner side when viewed from the axial direction, the circumferential dimension Wc of the magnetic body part is the circumferential dimension at the radially outer end of the magnetic body part 33. In this way, the circumferential dimension Wc of the magnetic body part 33 is set to obtain the maximum distance dimension of the magnetic body part 33. Also, the circumferential dimension Wc of the winding range C means the circumferential dimension of the area in which the coil part 40 can be arranged between the partition parts 32b. Therefore, the circumferential dimension Wc of the winding range C means the minimum distance between surface 32g facing the other circumferential side (-θ) of partition 32b arranged on one circumferential side (+θ) relative to the winding range C, and surface 32h facing one circumferential side (+θ) of partition 32b arranged on the other circumferential side (-θ) relative to the winding range C.

[0050] According to the rotating electric machine 1 of this embodiment, the ratio (Wst / Wc) of the circumferential dimension Wst of the magnetic body part 33 to the circumferential dimension Wc of the winding range C is set to less than 1, so that the winding range C can be secured wide in the circumferential direction. As a result, the cross-sectional area of ​​the coil part 40 can be secured sufficiently, and the amount of heat generated can be suppressed even when a large current is passed through the coil part 40, and the torque performance of the rotating electric machine 1 can be improved. By securing the winding range C wide in the circumferential direction, the radial dimension of the coil part 40 can be reduced while securing a sufficient cross-sectional area of ​​the coil part 40, and the rotating electric machine 1 can be made smaller in the radial direction. Furthermore, according to the rotating electric machine 1 of this embodiment, the winding range C is secured wide in the circumferential direction, so that the exposed range of the coil part 40 arranged in the winding range C toward the radial inside is wide. As a result, the coil part 40 is easily able to dissipate heat, and the temperature of the coil part 40 can be suppressed from rising too high. For the same reason, it is more preferable that the ratio (Wst / Wc) of the circumferential dimension Wst of the magnetic body portion 33 to the circumferential dimension Wc of the winding range C is less than 1 / 2.

[0051] In the stator 30 provided in the rotating electric machine 1 of this embodiment, the ratio (Hst / Hc) of the radial dimension Hst of the magnetic material portion 33 to the radial dimension Hc of the winding range C is preferably 1 / 2 or more, and more preferably 5 / 8 or more and 8 / 9 or less.

[0052] Here, the radial dimension Hst of the magnetic material part 33 is the maximum distance between the radially inner end 33c and the radially outer end 33d of the magnetic material part 33. Moreover, the radial dimension Hc of the winding range C is the maximum distance between the radially inner end and the radially outer end of the winding range C. In this embodiment, the radial dimension Hc of the winding range C is the radial distance from the inner circumferential surface 32e of the annular part 32a to the radially inner end of the coil part 40.

[0053] 4 is a graph showing the results of a simulation of the relationship between the ratio (Hst / Hc) of the radial dimension Hst of the magnetic body part 33 to the radial dimension Hc of the winding range C and the driving efficiency in the rotating electric machine 1 according to this embodiment. In this simulation, the ratio (Wst / Wc) of the circumferential dimension Wst of the magnetic body part 33 to the circumferential dimension Wc of the winding range C was set to 1 / 4. The rotation speed of the rotating electric machine 1 was set to 12000 rpm. The driving efficiency was calculated using general-purpose electromagnetic field analysis software JMAG (registered trademark), taking into account the effect of eddy currents flowing in the coil part 40.

[0054] 4, it was confirmed that the driving efficiency of the rotating electric machine 1 can be made 90% or more by setting the ratio (Hst / Hc) of the radial dimension Hst of the magnetic body part 33 to the radial dimension Hc of the winding range C to 1 / 2 or more. Furthermore, when the ratio (Hst / Hc) of the radial dimension Hst of the magnetic body part 33 to the radial dimension Hc of the winding range C is set to 5 / 8 or more and 8 / 9 or less, the driving efficiency can be made 92% or more, and a rotating electric machine 1 with even higher driving efficiency can be configured.

[0055] The configuration and effects of the rotating electrical machine 1 according to this embodiment will be summarized below. The rotating electric machine 1 according to the present embodiment includes a rotor 20 and a stator 30. The rotor 20 is rotatable about a central axis J. The stator 30 is disposed on one radial side of the rotor 20 (in the present embodiment, on the radially outer side). As shown in FIG. 3, the stator 30 includes a back yoke 31, a coil portion 40, and a plurality of partitions 32b. The back yoke 31 is annular about the central axis J. The coil portion 40 is disposed on the other radial side of the back yoke 31 (in the present embodiment, on the radially inner side). The plurality of partitions 32b partition a winding range C in which the coil portion 40 is disposed in the circumferential direction. The partitions 32b include a magnetic material portion 33 made of a magnetic material. A ratio (Wst / Wc) of a circumferential dimension Wst of the magnetic material portion 33 to a circumferential dimension Wc of the winding range C is less than 1 (Wst / Wc<1). The ratio (Hst / Hc) of the radial dimension Hst of the magnetic body portion 33 to the radial dimension Hc of the winding range C is equal to or greater than 1 / 2 (Hst / Hc≧1 / 2).

[0056] According to this configuration, the stator 30 has the partition portion 32b, so that the positional deviation of the coil portion 40 in the circumferential direction can be suppressed. Furthermore, the partition portion 32b has the magnetic body portion 33, so that the magnetic flux formed in the radial direction between the rotor 20 and the back yoke 31 can be concentrated in the magnetic body portion 33 when the rotating electric machine is driven, and the copper loss generated in the coil portion 40 can be suppressed. Furthermore, the ratio (Wst / Wc) of the circumferential dimension Wst of the magnetic body portion 33 to the circumferential dimension Wc of the winding range C is less than 1, so that the winding range C can be secured wide in the circumferential direction. As a result, the radial dimension of the coil portion 40 can be reduced while securing a sufficient cross-sectional area of ​​the coil portion 40, and the rotating electric machine 1 can be made compact in the radial direction. In addition, by setting the ratio (Hst / Hc) of the radial dimension Hst of the magnetic body portion 33 to the radial dimension Hc of the winding range C to 1 / 2 or more, the driving efficiency of the rotating electric machine 1 can be made 90% or more, as shown in FIG. 4.

[0057] In the rotating electric machine 1 according to this embodiment, the ratio (Wst / Wc) of the circumferential dimension Wst of the magnetic body part 33 to the circumferential dimension Wc of the winding range C is less than 1 / 2 (Wst / Wc<1 / 2). With this configuration, the winding range C can be made wider in the circumferential direction, and the rotating electric machine 1 can be made even smaller in the radial direction.

[0058] In the rotating electric machine 1 according to this embodiment, the ratio (Hst / Hc) of the radial dimension Hst of the magnetic body portion 33 to the radial dimension Hc of the winding range C is 5 / 8 or more and 8 / 9 or less. With this configuration, the driving efficiency of the rotating electric machine 1 can be further improved, as shown in FIG.

[0059] Moreover, in the rotating electric machine 1 according to this embodiment, the circumferential dimension Wc of the winding range C is equal to or smaller than the radial dimension Hc of the winding range C. According to this configuration, the coil portion 40 arranged in the winding range C can be made thinner in the radial direction, and as a result, the rotating electric machine 1 can be made smaller in the radial direction.

[0060] In addition, in the rotating electric machine 1 according to this embodiment, the coil section 40 has a wire bundle 42 consisting of a plurality of wires 42e connected in parallel to each other. The wire bundle 42 has a first portion 42a extending from one axial side to the other axial side, and a second portion 42b extending from the other axial side to one axial side. The arrangement of the plurality of wires 42e in the first portion 42a and the arrangement of the plurality of wires 42e in the second portion 42b are mirror symmetrical. With this configuration, the difference in electromotive force generated between different wires 42e can be further reduced. Therefore, it is possible to suppress the flow of circulating current between the wires 42e connected in parallel to each other, and the copper loss of the rotating electric machine 1 caused by the circulating current can be suppressed.

[0061] In addition, in the rotating electric machine 1 according to this embodiment, the rotor 20 is a surface permanent magnet type. That is, the rotating electric machine 1 according to this embodiment is a surface permanent magnet motor (SPM). Therefore, the magnet 25m of the rotor 20 directly faces the stator 30 magnetically, so that the magnetic force of the magnet 25m can be efficiently utilized, and the rotating electric machine 1 with high torque performance can be configured. On the other hand, the rotating electric machine 1 using the surface permanent magnet type rotor 20 also has a problem that the copper loss of the stator 30 tends to be significant. However, in the rotating electric machine 1 according to this embodiment, the copper loss is suppressed as described above, so that according to this embodiment, the rotating electric machine 1 with high efficiency and excellent torque performance can be configured.

[0062] Moreover, in the rotating electric machine 1 according to this embodiment, the rotor 20 has a plurality of magnets 25m whose magnetization directions alternate in the circumferential direction. As shown in FIG. 2, the magnets 25m are split magnets. With this configuration, it is possible to reduce eddy current loss that may occur in the magnets 25m. Furthermore, in the rotating electric machine 1 according to this embodiment, the magnets 25m are samarium-cobalt magnets. With this configuration, by using samarium-cobalt magnets with excellent heat resistance as the magnets 25m, it is possible to configure a rotating electric machine 1 that exhibits sufficient torque performance even at high temperatures.

[0063] Second embodiment Fig. 5 is a schematic cross-sectional view of a stator 130 of the second embodiment. In Fig. 5, the circumferential direction is shown as a straight line. The stator 130 of this embodiment differs from the above-mentioned embodiment mainly in the structure of the partition portion 132b. The same components as those of the above-mentioned embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0064] The stator 130 according to this embodiment has a back yoke 131, a plurality of partitions 132b, a coil portion 40, and insulating paper (not shown). In this embodiment, the back yoke 131 and the partitions 132b are configured from a yoke member 130Y, which is a single member. That is, the stator 130 includes the yoke member 130Y. The yoke member 130Y also includes a circular back yoke 131 and a plurality of partitions 132b protruding radially inward from the inner peripheral surface of the back yoke 131. The yoke member 130Y is made of a magnetic material, and is, for example, a laminated steel plate formed by stacking a plurality of electromagnetic steel plates in the axial direction. That is, the back yoke 131 and the partitions 132b are made of a magnetic material. Therefore, the partitions 132b included in the stator 130 according to this embodiment are magnetic material portions 133 entirely made of a magnetic material.

[0065] The multiple partitions 132b define a winding range C in which the coil portion 40 is disposed. An insulating paper (not shown) is disposed between the coil portion 40 and the yoke member 130Y. The insulating paper provides insulation between the coil portion 40 and the yoke member 130Y.

[0066] In the stator 130 according to this embodiment, as in the first embodiment, the ratio (Wst / Wc) of the circumferential dimension Wst of the magnetic body portion 133 (i.e., the partition portion 132b) to the circumferential dimension Wc of the winding range C is less than 1. This allows the winding range C to be wide in the circumferential direction, and the radial dimension of the coil portion 40 can be reduced while ensuring a sufficient cross-sectional area of ​​the coil portion 40. Furthermore, in the stator 130 according to this embodiment, when this ratio (Wst / Wc) is less than 1 / 2 (Wst / Wc<1 / 2), the winding range C can be even wider in the circumferential direction, and the rotating electric machine 1 can be even more compact in the radial direction.

[0067] In the stator 130 according to this embodiment, as in the first embodiment, the ratio (Hst / Hc) of the radial dimension Hst of the magnetic body portion 133 to the radial dimension Hc of the winding range C is 1 / 2 or more. Therefore, as shown in Fig. 4, the driving efficiency of the rotating electric machine 1 can be made 90% or more. Furthermore, in the stator 130 according to this embodiment, when this ratio (Hst / Hc) is 5 / 8 or more and 8 / 9 or less, the driving efficiency of the rotating electric machine 1 can be further improved.

[0068] As in the first embodiment, the stator 130 according to this embodiment has a circumferential dimension Wc of the winding range C that is equal to or smaller than the radial dimension Hc of the winding range C. This allows the coil portion 40 arranged in the winding range C to be thinned in the radial direction, and as a result, the rotating electric machine 1 can be made smaller in size in the radial direction.

[0069] Next, a modified magnet 225m that can be used in each of the above-mentioned embodiments will be described. FIG. 6 is a perspective view of the magnet 225m of this modified example. The modified magnet 225m is a bonded magnet. Therefore, the modified magnet 225m is manufactured by mixing the magnet powder 225k with a binder 225s such as plastic or rubber, solidifying and molding the mixture, and then magnetizing it. By making the magnet 225m a bonded magnet, the magnet powders 225k are insulated from each other by the binder 225s, making it difficult for eddy currents to occur in the magnet 225m. By employing the modified magnet 225m in the rotor 20 of each of the above-mentioned embodiments, it is possible to further reduce eddy current loss that may occur in the magnet 225m.

[0070] According to at least one of the embodiments described above, the rotor 20 has magnetic material parts 33, 133 and winding range C whose circumferential and radial dimensions satisfy the above-mentioned ranges, thereby making it possible to provide a rotating electric machine 1 with excellent energy efficiency by concentrating magnetic flux in the magnetic material part 33 and suppressing copper loss while ensuring a sufficiently wide winding range C to achieve miniaturization and weight reduction.

[0071] The rotating electric machine can be mounted on various drive objects such as automobiles, trains, and aircraft. Fig. 7 is a schematic diagram of an aircraft 90 as an example of a drive object on which the rotating electric machine 1 is mounted. The aircraft 90 is a hybrid aircraft propelled by a combination of a jet engine 91 and the rotating electric machine 1. The aircraft 90 has a pair of jet engines 91 and four rotating electric machines 1. The jet engines 91 are provided on main wings 98. The jet engines 91 generate thrust by exhausting air rearward.

[0072] The four rotating electric machines 1 are classified into two power generating rotating electric machines 1A and two drive rotating electric machines 1B. The power generating rotating electric machines 1A are each connected to the main shaft of a jet engine 91. The power generating rotating electric machine 1A generates electricity by the jet engine 91. Meanwhile, the drive rotating electric machine 1B is disposed below the vertical tail 99. The drive rotating electric machine 1B rotates a propulsion fan 93 to send air rearward and generate thrust. The drive rotating electric machine 1B is driven by electric power generated by the power generating rotating electric machine 1A. Note that if the power generating rotating electric machine 1A generates surplus electric power, this electric power may be charged into a battery and used when necessary.

[0073] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents described in the claims, as well as in the scope and spirit of the invention. [Explanation of symbols]

[0074] 1... rotating electric machine, 20... rotor, 25m, 225m... magnet, 30, 130... stator, 31, 131... back yoke, 32b, 132b... partition section, 33, 133... magnetic body section, 40... coil section, 42... wire bundle, 42a... first section, 42b... second section, 42e... wire, C... winding range, Hc, Hst... radial dimension, J... central axis, Wc, Wst... circumferential dimension, θ... circumferential direction

Claims

1. A rotor rotatable about a central axis; a stator disposed on one radial side of the rotor, The stator includes: An annular back yoke centered on the central axis; A coil portion disposed on the other radial side of the back yoke; a plurality of partitions that partition a winding range in which the coil portion is arranged in a circumferential direction; The partition portion has a magnetic material portion made of a magnetic material, a ratio of a circumferential dimension of the magnetic material portion to a circumferential dimension of the winding range is less than 1; The ratio of the radial dimension of the magnetic body portion to the radial dimension of the winding range is 1 / 2 or more. Rotating electric motor.

2. The ratio of the circumferential dimension of the magnetic material portion to the circumferential dimension of the winding range is less than 1 / 2. The rotating electric machine according to claim 1 .

3. The ratio of the radial dimension of the magnetic body portion to the radial dimension of the winding range is 5 / 8 or more and 8 / 9 or less. The rotating electric machine according to claim 1 .

4. The circumferential dimension of the winding range is equal to or less than the radial dimension of the winding range. The rotating electric machine according to claim 1 .

5. the coil portion has a wire bundle made up of a plurality of wires connected in parallel to each other, The wire bundle is A first portion extending from one axial side to the other axial side; a second portion extending from the other axial side toward the one axial side, The arrangement of the plurality of strands in the first portion and the arrangement of the plurality of strands in the second portion are mirror symmetrical. The rotating electric machine according to claim 1 .

6. The rotor is a surface magnet type. The rotating electric machine according to claim 1 .

7. The rotor has a plurality of magnets whose magnetization directions alternate in a circumferential direction, The magnet is a split magnet. The rotating electric machine according to claim 1 .

8. The rotor has a plurality of magnets whose magnetization directions alternate in a circumferential direction, The magnet is a samarium cobalt magnet. The rotating electric machine according to claim 1 .

9. The rotor has a plurality of magnets whose magnetization directions alternate in a circumferential direction, The magnet is a bonded magnet. The rotating electric machine according to claim 1 .

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