Rotor of permanent magnet rotating electrical machine and permanent magnet rotating electrical machine

Abstract

In a rotor (4) in which one pole is constituted by two magnet insertion holes provided in a V-shape, the strength of an inner-diameter bridge can be ensured even if the inner-diameter bridge is reduced in width.　A magnet insertion hole (45) comprises an inner-diameter flux barrier (45a) on the inner-diameter side and an outer-diameter flux barrier (45b) on the outer-diameter side of the position where a permanent magnet (43) is disposed. A lightening hole (46) is made in the rotor at a position overlapping a d-axis between inner-diameter flux barriers. The portion between an inner-diameter flux barrier and the lightening hole is an inner-diameter bridge (42a), and a straight line L1 perpendicular to the cross section of a minimum width part W1 of said inner-diameter bridge intersects the d-axis on the outer-diameter side or the inner-diameter side of said inner-diameter bridge.

Description

Rotor of permanent magnet rotating electric machine and permanent magnet rotating electric machine

[0001] The present disclosure relates to a rotor for a permanent magnet type rotating electric machine and a permanent magnet type rotating electric machine.

[0002] Known rotors for permanent magnet rotating electric machines include rotors with rotor cores each having a V-shaped magnet insertion hole facing the outer diameter. Permanent magnets are inserted into the magnet insertion holes of the rotor core. The portion of the rotor core between the inner diameter side of the V-shaped magnet insertion hole is called an inner diameter bridge, and the portion of the rotor core between the outer diameter side of the V-shaped magnet insertion hole and the outer diameter of the rotor core is called an outer diameter bridge. The width of the bridge is important in permanent magnet rotating electric machines, and narrowing the bridge width is effective for reducing leakage flux of the permanent magnet and increasing torque. On the other hand, the width of the bridge needs to be increased to improve the rotor core's resistance to centrifugal forces generated during rotation and inertial forces due to sudden acceleration and deceleration of rotation.

[0003] One conventional rotor for a permanent magnet rotating electric machine that addresses these issues is one that has an opening at the center of the magnetic poles of a pair of permanent magnets to increase magnetic resistance at the center of the magnetic poles and improve torque, and that also has two inner diameter bridges that connect the inner and outer diameter sides of the rotor core at the openings. In this rotor, the two inner diameter bridges are arranged symmetrically about the center line of the magnetic poles to ensure strength against centrifugal force (see, for example, Patent Document 1).

[0004] JP 2011-259688 A

[0005] However, in conventional rotors for permanent magnet rotating electric machines, when centrifugal force acts on a permanent magnet inserted into a V-shaped magnet insertion hole, the outer diameter side of the magnet insertion hole is pushed by the permanent magnet, so the direction of the reaction force is not parallel to the d-axis. Furthermore, the reaction force acting on the magnet insertion hole due to centrifugal force is also affected by the shape of the flux barriers provided at both ends of the permanent magnet insertion hole. The shape of the flux barriers is also a factor in the direction of the reaction force acting on the magnet insertion hole due to centrifugal force not being parallel to the d-axis. Thus, in conventional rotors for permanent magnet rotating electric machines, because the inner diameter bridge is parallel to the d-axis, the width of the inner diameter bridge must be increased to ensure the strength required to reduce stress on the outer diameter bridge. In other words, in conventional rotors for permanent magnet rotating electric machines, reducing the width of the inner diameter bridge prevents the inner diameter bridge from achieving the strength required to reduce stress on the outer diameter bridge.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a rotor for a permanent magnet type rotating electric machine having a V-shaped magnet insertion hole, which can ensure the strength of the inner diameter side bridge required to reduce stress on the outer diameter side bridge even if the width of the inner diameter side bridge is reduced.

[0007] The rotor of the permanent magnet rotating electric machine of the present disclosure includes a shaft serving as a rotation axis, a rotor core fastened to the shaft and having a plurality of magnet insertion holes, and a plurality of permanent magnets disposed in each of the plurality of magnet insertion holes, wherein, in a cross section perpendicular to the shaft, the rotor core has a plurality of magnetic poles disposed circumferentially, each magnetic pole consisting of two permanent magnets disposed in two magnet insertion holes that are V-shaped and open toward the outer diameter side about the d-axis, the magnet insertion holes have inner diameter-side flux barriers disposed on the inner diameter side of the positions where the permanent magnets are disposed, and outer diameter-side flux barriers disposed on the outer diameter side, the rotor core has lightening holes disposed between the inner diameter-side flux barriers of the plurality of magnet insertion holes at positions overlapping with the d-axis, and the portion of the rotor core between the inner diameter-side flux barrier and the lightening hole is an inner diameter-side bridge, and a line perpendicular to the cross section of the narrowest part of the inner diameter-side bridge intersects the d-axis on the outer diameter side or inner diameter side of the inner diameter-side bridge.

[0008] In the rotor of the permanent magnet rotating electric machine disclosed herein, a straight line perpendicular to the cross section of the narrowest part of the inner diameter side bridge intersects with the d axis on the outer diameter side or inner diameter side of the inner diameter side bridge, so that even if the width of the inner diameter side bridge is reduced, the strength of the inner diameter side bridge required to reduce stress in the outer diameter side bridge can be ensured.

[0009] 1 is a cross-sectional view of a permanent magnet rotating electric machine according to a first embodiment. 2 is a cross-sectional view of a rotor of a permanent magnet rotating electric machine according to a first embodiment. 3 is an enlarged cross-sectional view of a rotor of a permanent magnet rotating electric machine according to a first embodiment. 4 is an enlarged cross-sectional view of a rotor of a permanent magnet rotating electric machine according to a second embodiment. 5 is a cross-sectional view of a rotor of a permanent magnet rotating electric machine according to a third embodiment. 6 is an enlarged cross-sectional view of a rotor of a permanent magnet rotating electric machine according to a third embodiment. 7 is an enlarged cross-sectional view of a rotor of a permanent magnet rotating electric machine according to a third embodiment. 8 is an enlarged cross-sectional view of a rotor of a permanent magnet rotating electric machine according to a third embodiment. 9 is an enlarged cross-sectional view of a rotor of a permanent magnet rotating electric machine according to a third embodiment. 10 is an enlarged cross-sectional view of a rotor of a permanent magnet rotating electric machine according to a third embodiment. 11 is an enlarged cross-sectional view of a rotor of a permanent magnet rotating electric machine according to a fourth embodiment. 12 is an enlarged cross-sectional view of a rotor of a permanent magnet rotating electric machine according to a fifth embodiment.

[0010] Hereinafter, a rotor for a permanent magnet type rotating electric machine according to an embodiment of the present disclosure will be described in detail with reference to the drawings. Note that the same reference numerals in the various drawings indicate the same or corresponding parts.

[0011] Embodiment 1. Figure 1 is a cross-sectional view of a permanent magnet rotating electric machine according to embodiment 1. Figure 1 is a cross-sectional view taken in a direction parallel to the axial direction, which will be described later. The permanent magnet rotating electric machine 1 according to this embodiment includes a stator 3 fastened to the inner diameter side of a cylindrical frame 2, and a rotor 4 disposed on the inner diameter side of the stator 3 via a gap. The stator 3 is composed of a stator core 31 formed by stacking a plurality of electromagnetic steel plates in the axial direction, and a stator coil 32 wound around the stator core 31. Although not shown, the stator core 31 has a plurality of teeth formed thereon that protrude toward the inner diameter side, and the stator coil 32 is wound around these teeth.

[0012] The rotor 4 is composed of a shaft 41 serving as a rotation axis, a rotor core 42 fastened to the shaft 41, permanent magnets 43 inserted into magnet insertion holes provided in the rotor core 42, and a pair of end plates 44 that secure both axial ends of the rotor core 42 and the permanent magnets 43. The rotor core 42 is composed of multiple electromagnetic steel plates stacked in the axial direction. The shaft 41 is rotatably supported by bearings 5. The permanent magnets 43 are divided into multiple pieces in the axial direction and inserted into the magnet insertion holes. The end plates 44 prevent the permanent magnets 43 from moving axially, and may have holes or plates added to adjust the rotational balance.

[0013] In the permanent magnet rotating electric machine 1 of this embodiment, the rotor 4 rotates around the shaft 41 as the rotation axis. Hereinafter, the direction parallel to the shaft 41 will be referred to as the axial direction, the direction perpendicular to the shaft 41 as the radial direction, and the direction in which the shaft 41 rotates as the circumferential direction. Furthermore, the inner diameter side is the direction approaching the shaft 41 in the radial direction, and the outer diameter side is the direction moving away from the shaft 41 in the radial direction.

[0014] FIG. 2 is a cross-sectional view of the rotor 4 of the permanent magnet rotating electric machine 1 according to this embodiment. FIG. 2 is a cross-sectional view taken along the line A-A in FIG. 1 , i.e., a direction perpendicular to the axial direction. The shaft is omitted from FIG. 2 . The rotor core 42 is provided with V-shaped magnet insertion holes 45 that are symmetrical about the d-axis and open toward the outer diameter side. The magnet insertion holes 45 are composed of a pair of through-holes that penetrate the rotor core 42 in the axial direction. The permanent magnets 43 are inserted into the magnet insertion holes 45. The permanent magnets 43 inserted into the magnet insertion holes 45 are attached with adhesive so as to contact at least a portion of the surface of the magnet insertion holes 45. The permanent magnets 43 may be fixed in the magnet insertion holes 45 by filling the space between the magnet insertion holes 45 and the permanent magnets 43 with resin. One magnetic pole is composed of two V-shaped magnet insertion holes 45 and two permanent magnets 43, and multiple magnetic poles are arranged circumferentially. The central axis of the permanent magnets 43 arranged in a V-shape in one magnetic pole is the d-axis, and the central axis between adjacent magnetic poles is the q-axis. In the rotor 4 of this embodiment, a trapezoidal lightening hole 46 is provided at a position overlapping with the d-axis between the V-shaped magnet insertion holes 45 of one magnetic pole. This lightening hole 46 is a through-hole that passes through the rotor core 42 in the axial direction. From the perspective of adjusting the balance of the rotor, it is desirable that the lightening hole 46 have a structure that is line-symmetrical with respect to the d-axis.

[0015] A fixing hole 47 for fastening to the shaft is provided in the center of rotor core 42. The structure of the shaft inserted into fixing hole 47 of rotor core 42 is not limited to a cylindrical shape, and may be a hollow cylindrical boss structure. In the rotor of this embodiment, the rotor core and the shaft are fastened together by a process such as press fitting or shrink fitting. Although not shown, the fastening may also be performed via a fitting structure provided on the inner circumferential surface of fixing hole 47 of rotor core 42 and the outer circumferential surface of the shaft.

[0016] 3 is an enlarged cross-sectional view of the rotor 4 of the permanent magnet rotating electric machine 1 according to this embodiment. Fig. 3 is a cross-sectional view perpendicular to the axial direction, enlarging one pole. As shown in Fig. 3, an inner diameter-side flux barrier 45a is configured on the inner diameter side of the position where the permanent magnet 43 is inserted in the magnet insertion hole 45, and an outer diameter-side flux barrier 45b is configured on the outer diameter side. The portion of the rotor core 42 between the inner diameter-side flux barrier 45a and the weight-reducing hole 46 is the inner diameter-side bridge 42a, and the portion of the rotor core 42 between the outer diameter-side flux barrier 45b and the outer peripheral surface 49 of the rotor core 42 is the outer diameter-side bridge 42b.

[0017] 3, both sides of the inner diameter side bridge 42a are sandwiched between the linear portion 45L of the inner diameter side flux barrier 45a and the linear portion 46L of the weight-reducing hole 46. A straight line L1 perpendicular to the cross section of the minimum width portion W1 of the inner diameter side bridge 42a intersects with the d-axis on the outer diameter side of the inner diameter side bridge 42a. In other words, the distance between the inner diameter side bridge 42a and the d-axis increases toward the inner diameter side.

[0018] In a rotor 4 configured in this manner, when centrifugal force acts on the rotor 4, the amount of deformation of the rotor core 42 toward the outer diameter side increases as it approaches the d-axis relative to the q-axis side. As shown in FIG. 3 , when the inner diameter side bridges 42a are configured so that their distance from the d-axis increases toward the inner diameter side, shear stress is less likely to occur in the inner diameter side bridges 42a, and tensile stress becomes dominant. Therefore, the rotor 4 of this embodiment has the effect of improving the strength of the inner diameter side bridges 42a. As a result, even if the width of the inner diameter side bridges 42a is reduced, the strength of the inner diameter side bridges 42a required to reduce stress in the outer diameter side bridges 42b can be ensured.

[0019] Methods of processing electromagnetic steel sheets into the shape of a rotor core include wire cutting and press working, and press working is often used for products intended for mass production, including from a cost perspective. In press working, when punching out the electromagnetic steel sheet with a die, it is best to make the minimum width of the inner diameter side bridge at least twice the thickness of the electromagnetic steel sheet to prevent deformation of the punched portion.

[0020] FIG. 4 is an enlarged cross-sectional view of the rotor 4 of another permanent magnet rotating electric machine 1 according to this embodiment. FIG. 4 is a cross-sectional view perpendicular to the axial direction, enlarging one pole. As shown in FIG. 4 , the inner diameter bridge 42a is sandwiched between the linear portion 45L of the inner diameter flux barrier 45a and the linear portion 46L of the weight-reducing hole 46. A straight line L1 perpendicular to the cross section of the minimum width portion W1 of the inner diameter bridge 42a intersects with the d-axis on the inner diameter side of the inner diameter bridge 42a. In other words, the distance between the inner diameter bridge 42a and the d-axis increases toward the outer diameter side.

[0021] In a rotor 4 configured in this manner, when centrifugal force acts on the rotor 4, the amount of deformation of the rotor core 42 toward the outer diameter increases as it approaches the d-axis relative to the q-axis. As shown in FIG. 4 , when the inner diameter bridge 42a is configured so that its distance from the d-axis increases toward the outer diameter, shear stress is less likely to occur in the inner diameter bridge 42a, and tensile stress becomes dominant. Therefore, the rotor 4 of this embodiment has the effect of improving the strength of the inner diameter bridge 42a. As a result, even if the width of the inner diameter bridge 42a is reduced, the strength of the inner diameter bridge 42a required to reduce stress in the outer diameter bridge 42b can be ensured. Furthermore, reducing the width of the inner diameter bridge 42a reduces leakage magnetic flux from the permanent magnets 43, thereby improving torque.

[0022] In the rotor 4 shown in FIG. 4 , the inner diameter bridge 42 a is configured so that the distance from the d-axis increases toward the outer diameter, and therefore the outer diameter end of the inner diameter bridge 42 a is located closer to the outer diameter than the outer diameter end of the inner diameter bridge of the rotor shown in FIG. 3 . Therefore, in the rotor 4 shown in FIG. 4 , the load acting on the outer diameter bridge is supported by the inner diameter bridge, thereby reducing stress on the outer diameter bridge. In particular, in the rotor 4 shown in FIG. 4 , the inner diameter bridge 42 a is configured so that the distance from the d-axis decreases toward the inner diameter, and therefore the inner diameter bridge 42 a can mainly support the centrifugal force acting on the center of mass of the rotor components located outer diameter side of the inner diameter bridge 42 a. Therefore, the rotor 4 shown in FIG. 4 can more effectively reduce stress on the outer diameter bridge.

[0023] In the rotor of this embodiment, both sides of the inner diameter bridge 42a are sandwiched between the straight portions 45L of the inner diameter flux barrier 45a and the straight portions 46L of the lightening holes 46. The inner diameter bridge 42a does not necessarily have to be sandwiched between the straight portions, and may be sandwiched between a combination of straight portions and curved portions. Also, although the lightening holes 46 are trapezoidal, they may have other shapes. Furthermore, by arranging the magnet insertion holes 45, permanent magnets 43, and lightening holes 46 in line symmetry about the d-axis, imbalance in magnetic flux flow can be prevented.

[0024] Embodiment 2. Figure 5 is an enlarged cross-sectional view of a rotor of a permanent magnet type rotating electric machine according to embodiment 2. Figure 5 is a cross-sectional view in a direction perpendicular to the axial direction, showing one pole on an enlarged scale. The configuration of the permanent magnet type rotating electric machine according to this embodiment is the same as the configuration of the permanent magnet type rotating electric machine according to embodiment 1. In the permanent magnet type rotating electric machine according to this embodiment, the rotor structure is different from the rotor structure of embodiment 1.

[0025] In the rotor of this embodiment, as shown in FIG. 5, if an imaginary circle inscribed in the inner diameter side flux barrier 45a is denoted by C1, at least a portion of the weight-reducing holes 46 is provided on the inner diameter side of C1.

[0026] Fastening the shaft to the fixing hole of the rotor core generates stress in the fixing hole of the rotor core. This stress is transmitted to the inner diameter side flux barrier 45a and the lightening holes 46, which are provided on the inner diameter side of the rotor core. Deformation of the inner diameter side flux barrier 45a is also promoted by the centrifugal force of the permanent magnets 43 inserted in the magnet insertion holes 45. In the rotor of this embodiment, a portion of the lightening holes 46 is located closer to the inner diameter of the rotor core 42 than the inner diameter side flux barrier 45a, so that the stress generated in the fixing hole of the rotor core is transmitted mainly to the lightening holes 46. As a result, it is possible to reduce the stress transmitted to the inner diameter side flux barrier 45a.

[0027] Third Embodiment Figure 6 is a cross-sectional view of the rotor 4 of a permanent magnet rotating electric machine 1 according to a third embodiment. Figure 6 is a cross-sectional view in a direction perpendicular to the axial direction. The shaft is omitted from Figure 6. The configuration of the permanent magnet rotating electric machine according to this embodiment is similar to the configuration of the permanent magnet rotating electric machine according to the first embodiment. In the permanent magnet rotating electric machine according to this embodiment, the rotor structure is different from that of the rotor according to the first embodiment.

[0028] In the rotor core 42 of this embodiment, magnet insertion holes are arranged in two layers, with one magnetic pole symmetrical about the d-axis and V-shaped and open toward the outer diameter side. The magnet insertion hole on the inner diameter side is referred to as the first-layer magnet insertion hole 55, and the magnet insertion hole on the outer diameter side is referred to as the second-layer magnet insertion hole 65. The permanent magnets inserted into the first-layer magnet insertion holes 55 are referred to as the first-layer permanent magnets 53, and the permanent magnets inserted into the second-layer magnet insertion holes 65 are referred to as the second-layer permanent magnets 63. A trapezoidal weight reduction hole 46 is provided between the first-layer magnet insertion holes 55 at a position overlapping with the d-axis.

[0029] FIG. 7 is an enlarged cross-sectional view of the rotor 4 of the permanent magnet rotating electric machine 1 according to this embodiment. This cross-sectional view is perpendicular to the axial direction and shows an enlarged cross-sectional view of one pole. As shown in FIG. 7 , a first-layer inner diameter-side flux barrier 55a is configured in the first-layer magnet insertion hole 55 on the inner diameter side of the position where the first-layer permanent magnet 53 is inserted, and a first-layer outer diameter-side flux barrier 55b is configured on the outer diameter side. The portion of the rotor core 42 between the straight portion 55L of the first-layer inner diameter-side flux barrier 55a and the straight portion 46L of the weight-reducing hole 46 is the first-layer inner diameter-side bridge 52a, and the portion of the rotor core 42 between the first-layer outer diameter-side flux barrier 55b and the outer peripheral surface 49 of the rotor core 42 is the first-layer outer diameter-side bridge 52b. Furthermore, a second-layer inner diameter side flux barrier 65a is configured on the inner diameter side of the position where the second-layer permanent magnet 63 is inserted in the second-layer magnet insertion hole 65, and a second-layer outer diameter side flux barrier 65b is configured on the outer diameter side. The portion of the rotor core 42 between the inner diameter sides of the second-layer inner diameter side flux barriers 65a is the second-layer inner diameter side bridge 62a, and the portion of the rotor core 42 between the second-layer outer diameter side flux barrier 65b and the outer peripheral surface 49 of the rotor core 42 is the second-layer outer diameter side bridge 62b.

[0030] 7, both sides of the first-layer inner diameter side bridge 52a are sandwiched between the linear portion 55L of the first-layer inner diameter side flux barrier 55a and the linear portion 46L of the weight-reducing hole 46. A straight line L1 perpendicular to the cross section of the minimum width portion W1 of the first-layer inner diameter side bridge 52a intersects with the d-axis on the outer diameter side of the first-layer inner diameter side bridge 52a. In other words, the first-layer inner diameter side bridge 52a is configured so that the distance from the d-axis increases toward the inner diameter side.

[0031] In a rotor 4 configured in this manner, when centrifugal force acts on the rotor 4, the amount of deformation of the rotor core 42 toward the outer diameter increases closer to the d-axis than to the q-axis. As shown in FIG. 7 , when the first-layer inner diameter side bridges 52a are configured so that their distance from the d-axis increases toward the inner diameter side, shear stress is less likely to occur in the first-layer inner diameter side bridges 52a, and tensile stress becomes dominant. Therefore, the rotor 4 of this embodiment has the effect of improving the strength of the first-layer inner diameter side bridges 52a. As a result, even if the width of the first-layer inner diameter side bridges 52a is reduced, the strength of the first-layer inner diameter side bridges 52a required to reduce stress in the first-layer outer diameter side bridges 52b can be ensured. Furthermore, reducing the width of the first-layer inner diameter side bridges 52a reduces leakage flux from the first-layer permanent magnets 53, thereby improving torque.

[0032] FIG. 8 is an enlarged cross-sectional view of the rotor 4 of another permanent magnet rotating electric machine 1 according to this embodiment. FIG. 8 is a cross-sectional view perpendicular to the axial direction, enlarging one pole. As shown in FIG. 8 , the first-layer inner diameter side bridge 52a is sandwiched on both sides between the linear portion 55L of the first-layer inner diameter side flux barrier 55a and the linear portion 46L of the weight-reducing hole 46. A line L1 perpendicular to the cross section of the minimum width portion W1 of the first-layer inner diameter side bridge 52a intersects with the d-axis on the inner diameter side of the first-layer inner diameter side bridge 52a. In other words, the first-layer inner diameter side bridge 52a is configured such that the distance from the d-axis increases toward the outer diameter side.

[0033] In a rotor with one pole configured with a two-layer magnet insertion hole, the first-layer outer diameter bridge 52b supports not only the centrifugal force generated in the first-layer permanent magnet 53 but also the centrifugal force generated in the second-layer permanent magnet 63. In the rotor 4 shown in FIG. 8, the first-layer inner diameter bridge 52a is configured so that its distance from the d-axis increases toward the outer diameter. This allows the direction of force F, which is generated in the second-layer permanent magnet 63 and pushes the second-layer magnet insertion hole 65 toward the outer diameter, to be parallel to the direction of the straight line L1 of the first-layer inner diameter bridge 52a. Therefore, the rotor shown in FIG. 8 can more effectively reduce stress in the first-layer outer diameter bridge. The direction of force F, which pushes the second-layer magnet insertion hole 65 toward the outer diameter, can be calculated, for example, using numerical simulation.

[0034] FIG. 9 is an enlarged cross-sectional view of the rotor 4 of another permanent magnet rotating electric machine 1 according to this embodiment. FIG. 9 is a cross-sectional view perpendicular to the axial direction, enlarging one pole. As shown in FIG. 9 , both sides of the first-layer inner diameter side bridge 52a are sandwiched between the curved portion 45C of the first-layer inner diameter side flux barrier 55a and the straight portion 46L of the weight-reducing hole 46. A straight line L1 perpendicular to the cross section of the minimum width portion W1 of the first-layer inner diameter side bridge 52a intersects with the d-axis on the inner diameter side of the first-layer inner diameter side bridge 52a. That is, the first-layer inner diameter side bridge 52a is configured such that the distance from the d-axis increases toward the outer diameter side.

[0035] In the rotor 4 shown in Fig. 8, the first-layer inner diameter side bridge 52a is sandwiched between the straight portion 45L of the first-layer inner diameter side flux barrier 55a and the straight portion 46L of the lightening hole 46. In this case, the curvature of both radial ends of the first-layer inner diameter side bridge 52a is small, and large stress is generated at these ends. In the rotor 4 shown in Fig. 9, the first-layer inner diameter side bridge 52a is sandwiched between the curved portion 45C of the first-layer inner diameter side flux barrier 55a and the straight portion 46L of the lightening hole 46. Therefore, the curvature of both radial ends of the first-layer inner diameter side bridge 52a can be increased, and stress generated at these ends can be reduced.

[0036] FIG. 10 is an enlarged cross-sectional view of the rotor 4 of another permanent magnet rotating electric machine 1 according to this embodiment. FIG. 10 is a cross-sectional view perpendicular to the axial direction, enlarging one pole. As shown in FIG. 10 , both sides of the first-layer inner diameter side bridge 52a are sandwiched between the straight portion 45L of the first-layer inner diameter side flux barrier 55a and the curved portion 46C of the weight-reducing hole 46. A straight line L1 perpendicular to the cross section of the minimum width portion W1 of the first-layer inner diameter side bridge 52a intersects with the d-axis on the inner diameter side of the first-layer inner diameter side bridge 52a. That is, the first-layer inner diameter side bridge 52a is configured such that the distance from the d-axis increases toward the outer diameter side.

[0037] As with the rotor shown in FIG. 9, the rotor 4 shown in FIG. 10 can increase the curvature of both radial ends of the first layer inner diameter side bridge 52a, thereby reducing the stress generated at these ends.

[0038] FIG. 11 is an enlarged cross-sectional view of the rotor 4 of another permanent magnet rotating electric machine 1 according to this embodiment. FIG. 11 is a cross-sectional view perpendicular to the axial direction, enlarging one pole. As shown in FIG. 11 , both sides of the first-layer inner diameter side bridge 52a are sandwiched between the curved portion 45C of the first-layer inner diameter side flux barrier 55a and the straight portion 46L of the weight-reducing hole 46. A line L1 perpendicular to the cross section of the narrowest portion of the first-layer inner diameter side bridge 52a intersects with the d-axis on the inner diameter side of the first-layer inner diameter side bridge 52a. That is, the first-layer inner diameter side bridge 52a is configured such that the distance from the d-axis increases toward the outer diameter side.

[0039] 11 , that is, the region of the rotor core 42 surrounded by the d-axis and imaginary plane A that divides the first-layer inner diameter side bridges 52a in the radial direction and imaginary plane B that divides the first-layer outer diameter side bridges 52b in the circumferential direction, as well as the region of the first-layer permanent magnets 53 and second-layer permanent magnets 63, is defined as the outer diameter side region of the rotor 4. Here, when the first-layer inner diameter side bridges 52a and the first-layer outer diameter side bridges 52b are considered to be elastically deformable beams, and the mass of the outer diameter side region is considered to be added mass, and a beam having a concentrated mass is modeled with one degree of freedom, it is generally known that approximately one-third of the mass of the beam, or more precisely 33 / 140, should be added to the free end. For this reason, imaginary planes A and B are set at positions where the respective masses of the shaded regions of the first-layer inner diameter side bridge 52a and the first-layer outer diameter side bridge 52b included in the outer diameter side region are approximately one-third of the total mass of the first-layer inner diameter side bridge 52a and the first-layer outer diameter side bridge 52b. The region of the rotor core 42 surrounded by the imaginary planes A and B set in this way and the d-axis, as well as the region of the first-layer permanent magnets 53 and the second-layer permanent magnets 63, are defined as the outer diameter side region, and the center of mass of this outer diameter side region is defined as point CW. In the rotor of this embodiment, as shown in FIG. 11 , a straight line L1 passes through point CW.

[0040] The rotor 4 configured in this manner can reduce stress generated in the second-layer outer-diameter bridge 62b by supporting the centrifugal force generated in the outer-diameter region of the rotor 4 with the first-layer inner-diameter bridge 52a and the first-layer outer-diameter bridge 52b. Furthermore, in the rotor 4 of this embodiment, the line L1 passes through point CW, so the first-layer inner-diameter bridge 52a can mainly support the centrifugal force applied to the center of mass of the outer-diameter region of the rotor 4. As a result, stress in the first-layer outer-diameter bridge 52b can be more effectively reduced.

[0041] When resin is filled in the outer diameter region of the rotor 4 to fix the permanent magnets in the magnet insertion holes, the mass of the resin must also be taken into consideration.

[0042] Fourth Embodiment Figure 12 is an enlarged cross-sectional view of the rotor 4 of a permanent magnet rotating electric machine 1 according to a fourth embodiment. Figure 12 is a cross-sectional view in a direction perpendicular to the axial direction, showing one pole on an enlarged scale. The configuration of the permanent magnet rotating electric machine according to this embodiment is similar to the configuration of the permanent magnet rotating electric machine according to the first embodiment. In the permanent magnet rotating electric machine according to this embodiment, the rotor structure is different from that of the rotor according to the first embodiment.

[0043] In the rotor of embodiment 3 shown in FIG. 7 , the second-layer magnet insertion holes 65 are symmetrical about the d-axis and have a V-shape that opens toward the outer diameter. In the rotor 4 of this embodiment, as shown in FIG. 12 , the second-layer magnet insertion holes 65 are symmetrical about the d-axis and extend perpendicular to the d-axis. The first-layer inner bridge 52a is sandwiched between the linear portion 55L of the first-layer inner flux barrier 55a and the linear portion 46L of the weight-reducing hole 46. Furthermore, a line L1 perpendicular to the cross section of the minimum width portion W1 of the first-layer inner bridge 52a intersects with the d-axis on the outer diameter side of the first-layer inner bridge 52a. In other words, the first-layer inner bridge 52a is configured such that its distance from the d-axis increases toward the inner diameter.

[0044] In the rotor 4 configured in this manner, the strength of the first-layer inner diameter side bridges 52a necessary for reducing stress on the first-layer outer diameter side bridges 52b can be ensured even if the width of the first-layer inner diameter side bridges 52a is reduced, as in the rotor of embodiment 3. Furthermore, by reducing the width of the first-layer inner diameter side bridges 52a, leakage flux of the first-layer permanent magnets 53 can be reduced, thereby improving torque.

[0045] Fifth Embodiment Figure 13 is an enlarged cross-sectional view of the rotor 4 of a permanent magnet rotating electric machine 1 according to a fifth embodiment. Figure 13 is a cross-sectional view in a direction perpendicular to the axial direction, showing one pole on an enlarged scale. The configuration of the permanent magnet rotating electric machine according to this embodiment is similar to the configuration of the permanent magnet rotating electric machine according to the first embodiment. In the permanent magnet rotating electric machine according to this embodiment, the rotor structure is different from that of the rotor according to the first embodiment.

[0046] In the rotor 4 of this embodiment, as in the rotor of embodiment 3 shown in Fig. 7 , magnet insertion holes are arranged in two layers, with one magnetic pole symmetrical about the d axis and V-shaped and open toward the outer diameter side. As shown in Fig. 13 , a first-layer inner diameter side flux barrier 55a is configured in the first-layer magnet insertion hole 55 on the inner diameter side of the position where the first-layer permanent magnet 53 is inserted, and a first-layer outer diameter side flux barrier 55b is configured on the outer diameter side. The portion of the rotor core 42 between the first-layer inner diameter side flux barrier 55a and the weight-reducing hole 46 is the first-layer inner diameter side bridge 52a, and the portion of the rotor core 42 between the first-layer outer diameter side flux barrier 55b and the outer peripheral surface 49 of the rotor core 42 is the first-layer outer diameter side bridge 52b. Furthermore, second-layer inner diameter side flux barriers 65a are configured in the second-layer magnet insertion holes 65 on the inner diameter side of the positions where the second-layer permanent magnets 63 are inserted, and second-layer outer diameter side flux barriers 65b are configured on the outer diameter side. The portions of the rotor core 42 between the inner diameter sides of the second-layer inner diameter side flux barriers 65a are second-layer inner diameter side bridges 62a, and the portions of the rotor core 42 between the second-layer outer diameter side flux barriers 65b and the outer peripheral surface 49 of the rotor core 42 are second-layer outer diameter side bridges 62b. Trapezoidal weight-reducing holes 46 are provided between the first-layer magnet insertion holes 55 at positions overlapping with the d-axis.

[0047] In the rotor 4 of this embodiment, d1 is the shortest distance between the first-layer magnet insertion hole 55 and the second-layer magnet insertion hole 65. L2 is the line representing the position d1 away from the second-layer magnet insertion hole 65 toward the inner diameter, and L3 is the line extending the short side of the first-layer permanent magnet 53 toward the outer diameter. In the rotor 4 of this embodiment, the weight reduction holes 46 are located on the inner diameter side of lines L2 and L3.

[0048] A rotor configured in this manner can increase the area occupied by the lightening holes while reducing the effect on the magnetic flux generated by the first layer permanent magnet 53, thereby making the rotor lighter.

[0049] Although various exemplary embodiments are described in this disclosure, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not illustrated are contemplated within the scope of the technology disclosed in this specification. For example, this includes cases where at least one component is modified, added, or omitted, or where at least one component is extracted and combined with components of another embodiment.

[0050] REFERENCE SIGNS LIST 1 Permanent magnet rotating electric machine, 2 Frame, 3 Stator, 4 Rotor, 5 Bearing, 31 Stator core, 32 Stator coil, 41 Shaft, 42 Rotor core, 42a Inner diameter side bridge, 42b Outer diameter side bridge, 43 Permanent magnet, 44 End plate, 45 Magnet insertion hole, 45a Inner diameter side flux barrier, 45b Outer diameter side flux barrier, 46 Lightweighting hole, 47 Fixing hole, 49 Outer peripheral surface, 52a First layer inner diameter side bridge, 52b First layer outer diameter side bridge, 53 First layer permanent magnet, 55 First layer magnet insertion hole, 55a First layer inner diameter side flux barrier, 55b First layer outer diameter side flux barrier, 62a Second layer inner diameter side bridge, 62b Second layer outer diameter side bridge, 63 Second layer permanent magnet, 65 Second layer magnet insertion hole, 65a second layer inner diameter side flux barrier, 65b second layer outer diameter side flux barrier.

Claims

1. A rotor for a permanent magnet type rotating electric machine having a shaft serving as a rotating shaft, a rotor core having a plurality of magnet insertion holes fastened to the shaft, and a plurality of permanent magnets respectively arranged in the plurality of magnet insertion holes, wherein in a cross section perpendicular to the shaft, a plurality of magnetic poles are arranged circumferentially in the rotor core, and one magnetic pole is composed of two of the permanent magnets respectively arranged in two of the magnet insertion holes which are arranged in a V-shape opening outward from the d-axis, and an inner diameter side flux barrier is arranged on the inner diameter side of the position where the permanent magnets are arranged in the magnet insertion holes, and an outer diameter side flux barrier is arranged on the outer diameter side, and a weight-reducing hole is provided in the rotor core at a position overlapping the d-axis between the inner diameter side flux barriers of the plurality of magnet insertion holes, A rotor for a permanent magnet type rotating electric machine, characterized in that the portion of the rotor core between the inner diameter side flux barrier and the weight-reducing hole is an inner diameter side bridge, and a straight line perpendicular to the cross section of the smallest width part of the inner diameter side bridge intersects with the d-axis on the outer diameter side or inner diameter side of the inner diameter side bridge.

2. A rotor for a permanent magnet type rotating electric machine as described in claim 1, characterized in that the two magnet insertion holes that constitute one magnetic pole are arranged symmetrically about the d-axis.

3. A rotor for a permanent magnet type rotating electric machine according to claim 1 or 2, characterized in that at least a portion of the weight-reducing holes is located on the inner diameter side of an imaginary circle inscribed in the inner diameter side bridge.

4. A rotor for a permanent magnet type rotating electric machine as described in any one of claims 1 to 3, characterized in that one magnetic pole has two magnet insertion holes arranged in two layers radially, each hole being V-shaped and opening toward the outer diameter side around the d-axis, and the weight-reducing hole being formed between the two magnet insertion holes on the inner diameter side.

5. A rotor for a permanent magnet type rotating electric machine as described in claim 4, characterized in that the direction of the centrifugal force acting on the permanent magnet placed in the magnet insertion hole on the outer diameter side is parallel to the direction of a straight line perpendicular to the cross section of the narrowest part of the inner diameter side bridge.

6. A rotor for a permanent magnet type rotating electric machine as described in claim 4 or 5, characterized in that a straight line perpendicular to the cross section of the narrowest part of the inner diameter side bridge passes through the center of mass of the rotor on the outer diameter side of the inner diameter side bridge.

7. A rotor for a permanent magnet type rotating electric motor described in any one of claims 4 to 6, characterized in that when the shortest distance between the magnet insertion hole on the inner diameter side and the magnet insertion hole on the outer diameter side is d1, the line indicating a position d1 away from the magnet insertion hole on the outer diameter side toward the inner diameter is L2, and the line extending the inner diameter side edge of the permanent magnet placed in the magnet insertion hole on the inner diameter side toward the outer diameter is L3, the weight reduction hole is located on the inner diameter side of L2 and L3.

8. A rotor for a permanent magnet type rotating electric motor described in any one of claims 1 to 3, characterized in that a second magnet insertion hole is provided on the outer diameter side of the two magnet insertion holes that are arranged in a V-shape centered on the d axis and open toward the outer diameter side, a second permanent magnet is arranged in the second magnet insertion hole, the second magnet insertion holes are arranged symmetrically on the left and right sides of the d axis, and the longitudinal direction of the second magnet insertion hole is perpendicular to the d axis.

9. A permanent magnet type rotating electric machine comprising a stator having a stator core and a stator coil wound around said stator core, and a rotor of a permanent magnet type rotating electric machine according to any one of claims 1 to 8, which is arranged rotatably relative to said stator via a gap.

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