Rotor and rotating electric machine

The rotor includes: a rotor core having a plurality of insertion holes penetrating in an axial direction at intervals in a circumferential direction; and magnets respectively provided in the insertion holes. A space is formed between a hole inner side peripheral surface of each insertion hole and a magnet inner side peripheral surface of each magnet. An adhesion layer portion is formed between a hole outer side peripheral surface of each insertion hole and a magnet outer side peripheral surface of each magnet, and the hole outer side peripheral surface of each insertion hole and the magnet outer side peripheral surface of each magnet with which the adhesion layer portion contacts are formed in a flat-surface shape. A width in a radial direction of the space is longer than a width in the radial direction of the adhesion layer portion.

TECHNICAL FIELD

The present invention relates to a rotor and a rotating electric machine in which reduction of torque performance can be suppressed and magnets can be stably held.

BACKGROUND ART

In recent years, rotating electric machines used as electric motors and electric generators are required to have small sizes and be capable of high-speed rotation and high output. In one of methods for realizing such a rotating electric machine having a small size and capable of high-speed rotation and high output, reluctance torque is utilized with a shape in which magnets are embedded in a rotor, and the reluctance torque is combined with magnet torque due to magnets, thereby increasing generated torque.

However, in the case of attempting to achieve size reduction, high-speed rotation, and high output of a rotating electric machine, there is a problem that generated torque might greatly vary depending on the shapes of magnets embedded in the rotor. Accordingly, it is conventionally proposed that the magnet shape is formed to be convex inward in the radial direction from a rectangular shape, thereby utilizing reluctance torque and improving generated torque (see, for example, Patent Document 1).

CITATION LIST

Patent Document

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

In the conventional rotor and rotating electric machine, the magnet shape is formed to be convex inward in the radial direction, thereby improving torque. However, using such a magnet shape as to be convex inward in the radial direction causes problems that it is difficult to mold such magnets, it is difficult to perform positioning for insertion into magnet insertion holes, it is difficult to hold the magnets at the time of insertion thereof, and it is difficult to apply an adhesive agent to the magnets.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a rotor and a rotating electric machine in which reduction of torque performance can be suppressed and magnets can be stably held.

Solution to the Problems

A rotor according to the present invention includes: a rotor core in which a plurality of insertion holes penetrating in an axial direction are formed at intervals in a circumferential direction; and magnets respectively provided in the insertion holes. A hole inner side peripheral surface of each insertion hole and a magnet inner side peripheral surface of each magnet are not in contact with each other so that a space is formed therebetween. An adhesion layer portion is formed between a hole outer side peripheral surface of each insertion hole and a magnet outer side peripheral surface of each magnet, and the hole outer side peripheral surface of each insertion hole and the magnet outer side peripheral surface of each magnet with which the adhesion layer portion contacts are formed in a flat-surface shape. A width in a radial direction of the space is longer than a width in the radial direction of the adhesion layer portion.

A rotating electric machine according to the present invention includes: the rotor configured as described above; a rotary shaft for rotating the rotor core; and a stator having a coil and located with an air gap from the rotor.

Effect of the Invention

In the rotor and the rotating electric machine according to the present invention, reduction of torque performance can be suppressed and magnets can be stably held.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the invention of the present application will be described.FIG. 1is a plan view showing the structure of a rotor according to embodiment 1 of the present invention.FIG. 2is a partially enlarged plan view showing the structure of a ⅛ model of the rotor shown inFIG. 1.FIG. 3is a partially enlarged plan view showing the structure of half of the rotor shown inFIG. 2.FIG. 4is a perspective view showing the structure of a rotating electric machine formed with the rotor shown inFIG. 1.FIG. 5is a plan view showing the structure of the rotating electric machine shown inFIG. 4.FIG. 6shows magnet usage rates of the rotating electric machine of the present invention and a rotating electric machine of a comparative example. Only inFIG. 2, hatching is applied for the purpose of understanding structures. In the other figures, the same structures are shown and therefore hatching is omitted.

In the present embodiment, the case of using a permanent-magnet-type rotating electric machine1with eight poles and forty-eight slots will be described as an example. It is noted that the number of poles and the number of slots in the rotating electric machine1can be increased or decreased as appropriate, and rotating electric machines in such cases can also be configured in the same manner in the present embodiment and the other embodiments. Therefore, the description thereof is omitted as appropriate.

InFIG. 4andFIG. 5, the rotating electric machine1is composed of a stator2, a rotor3, and a shaft4. The stator2, the rotor3, and the shaft4are arranged in this order from the outer circumferential side of the rotating electric machine1. The stator2is arranged with an air gap5, which is a space, from the rotor3. A length L of the air gap5in a radial direction X is set at 0.1 mm to 2.5 mm.

The stator2includes a stator core20and a coil21. The stator core20is formed in an annular shape. The stator core20is formed by stacking a plurality of electromagnetic steel sheets in an axial direction Y, for example. The thickness of each of the electromagnetic steel sheets to be used is often 0.1 mm to 1.0 mm. In the present embodiment, the case of forming the stator core20from electromagnetic steel sheets is shown as an example, but without limitation thereto, the stator core20may be formed from materials other than electromagnetic steel sheets, and the same applies to the other embodiments. Therefore, the description thereof is omitted as appropriate. The coil21wound around the stator core20may be formed in either a distributed winding manner or a concentrated winding manner.

The rotor3is formed with a rotor core30fixed to the shaft4inserted on the center axis. The rotor3is a permanent magnet rotor having the rotor core30arranged inside the stator2, and having permanent magnets6. The shaft4is fixed to the rotor core30by, for example, shrink fit or press fit.

Next, the details of the structure of the rotor3will be described with reference toFIG. 1toFIG. 3. As shown inFIG. 1, the rotor3is composed of: the rotor core30in which a plurality of insertion holes7penetrating in the axial direction Y are formed at intervals in a circumferential direction Z; the permanent magnets6(hereinafter, permanent magnets are referred to as magnets) arranged in the respective insertion holes7; and the shaft4for rotating the rotor core30.

Therefore, the magnets6are formed in such sizes and shapes as to be able to be inserted into the respective insertion holes7. In the following description, when the magnets6and the insertion holes7are mentioned, all the magnets6and insertion holes7in the rotor3are referred to.

As shown inFIG. 2, a plurality of insertion holes7are formed at intervals in the circumferential direction Z of the rotor core30, and formed in a plurality of layers in the radial direction X. In the present embodiment, the case where the insertion holes7are arranged in two layers in the radial direction X will be described. The insertion holes7include two layers of a first insertion hole71and a second insertion hole72. In the first insertion hole71, a first bridge portion41is formed on the magnetic pole center axis, and thus the first insertion hole71is divided into a first insertion hole71A and a first insertion hole71B having shapes line-symmetric between left and right with respect to the center axis. In the second insertion hole72, a second bridge portion42is formed on the magnetic pole center axis, and thus the second insertion hole72is divided into a second insertion hole72A and a second insertion hole72B having shapes line-symmetric between left and right with respect to the center axis.

A first magnet61A and a first magnet61B are respectively inserted in the first insertion hole71A and the first insertion hole71B, and a second magnet62A and a second magnet62B are respectively inserted into the second insertion hole72A and the second insertion hole72B. Therefore, first magnets61are composed of the first magnet61A and the first magnet61B, and second magnets62are composed of the second magnet62A and the second magnet62B. Regarding each magnet6, in particular, as shown inFIG. 3, a width H1thereof in the radial direction X on a side near the magnetic pole center axis of the insertion hole7is longer than a width H2in the radial direction X on a side far from the magnetic pole center axis of the insertion hole7.

As shown inFIG. 3, a first adhesion layer portion11is formed between a hole outer side peripheral surface80of the first insertion hole71and a magnet outer side peripheral surface90of the first magnet61, thereby fixing them. In addition, a second adhesion layer portion12is formed between a hole outer side peripheral surface80of the second insertion hole72and a magnet outer side peripheral surface90of the second magnet62, thereby fixing them.

Each hole outer side peripheral surface80at which the first adhesion layer portion11is formed and which is a side surface in the circumferential direction Z on the outer side in the radial direction X of the first insertion hole71, is formed in a flat-surface shape. Each magnet outer side peripheral surface90at which the first adhesion layer portion11is formed and which is a surface in the circumferential direction Z on the outer side in the radial direction X of the first magnet61, is formed in a flat-surface shape. Similarly, each hole outer side peripheral surface80at which the second adhesion layer portion12is formed and which is a side surface in the circumferential direction Z on the outer side in the radial direction X of the second insertion hole72, is formed in a flat-surface shape. Each magnet outer side peripheral surface90at which the second adhesion layer portion12is formed and which is a surface in the circumferential direction Z on the outer side in the radial direction X of the second magnet62, is formed in a flat-surface shape.

A hole inner side peripheral surface81which is a side surface in the circumferential direction Z on the inner side in the radial direction X of each insertion hole71,72, is formed in an arc-surface shape that is convex inward in the radial direction X of the rotor3. A magnet inner side peripheral surface91which is a surface in the circumferential direction Z on the inner side in the radial direction X of each magnet61,62, is formed in an arc-surface shape that is convex inward in the radial direction X of the rotor3.

The insertion hole7and the magnet6are adhered by each adhesion layer portion11,12. The hole inner side peripheral surface81of the first insertion hole71and the magnet inner side peripheral surface91of the first magnet61are not in contact with each other and a space is provided therebetween to form a first gap portion51. The hole inner side peripheral surface81of the second insertion hole72and the magnet inner side peripheral surface91of the second magnet62are not in contact with each other and a space is provided therebetween to form a second gap portion52.

A width T1in the radial direction X of the first gap portion51is longer than a width T2in the radial direction X of the first adhesion layer portion11. Similarly, a width T3in the radial direction X of the second gap portion52is longer than a width T4in the radial direction X of the second adhesion layer portion12. Specifically, the widths T2, T4are about 0.03 mm to 0.15 mm. The widths T1, T3are longer than the widths T2, T4but are about 1 mm or less.

On the hole inner side peripheral surface81of each first insertion hole71A,71B, a first projection82is formed which projects outward in the radial direction X and contacts with a circumferential-direction-side end surface93of each first magnet61A,61B on a side opposite to the first bridge portion41side in the circumferential direction Z. On the first bridge portion41between the first insertion holes71, a second projection83is formed which projects toward the first magnet61side in each first insertion hole71and contacts with each first magnet61. Each projection82,83serves as a contact stopper for preventing the first magnet61inserted in the first insertion hole71from moving during rotation of the rotor core30.

Hole circumferential-direction-side end surfaces84of the first insertion holes71A,71B are formed in an arc shape. In the first insertion holes71A,71B, there are spaces where the first magnets61A,61B are not present, and these spaces serve as flux barrier portions8.

On the hole inner side peripheral surface81of each second insertion hole72A,72B, a first projection82is formed which projects outward in the radial direction X and contacts with a circumferential-direction-side end surface93of each second magnet62A,62B on a side opposite to the second bridge portion42side in the circumferential direction Z. On the second bridge portion42between the second insertion holes72, a second projection83is formed which projects on the second magnet62side in each second insertion hole72and contacts with each second magnet62. Each projection82,83serves as a contact stopper for preventing the second magnet62inserted in the second insertion hole72from moving during rotation of the rotor core30.

Hole circumferential-direction-side end surfaces84of the second insertion holes72A,72B are formed in an arc shape. In the second insertion holes72A,72B, there are spaces where the second magnets62A,62B are not present, and these spaces serve as flux barrier portions8.

Next, a method for manufacturing the rotor of the rotating electric machine of embodiment 1 configured as described above will be described. First, an adhesive agent is applied on the magnet outer side peripheral surface90of each magnet6. As the adhesive agent, any material that enables fixation between the magnet6and the insertion hole7may be used. For example, the adhesive agent is applied with a thickness of about 0.03 mm to 0.15 mm (corresponding to widths T2, T4). Next, the magnet6is inserted into the insertion hole7. At this time, in order that the adhesive agent will not adhere to a part other than a necessary part, the magnet6is inserted such that the magnet outer side peripheral surface90thereof on the side where the adhesive agent is applied moves along the hole outer side peripheral surface80of the insertion hole7.

Next, each magnet6is moved outward in the radial direction X so that the adhesive agent on the magnet6is pressed to the hole outer side peripheral surface80, to cure the adhesive agent. This pressing step may be performed on any condition that does not cause the magnet6or the insertion hole7to crack or chip, and means and the number of times for pressing the magnet6to the insertion hole7are not particularly limited. Thus, the first adhesion layer portions11and the second adhesion layer portions12are each formed between the magnet outer side peripheral surface90of the magnet6and the hole outer side peripheral surface80of the insertion hole7. In addition, the circumferential-direction-side end surfaces93of each magnet6are in contact with the first projection82and the second projection83.

Here, the magnet outer side peripheral surface90of each magnet6and the hole outer side peripheral surface80of each insertion hole7, on which the first adhesion layer portion11and the second adhesion layer portion12are adhered, are formed in a flat-surface shape, and therefore, as compared to the case where these surfaces are formed in a curved-surface shape, positioning of the magnet6is facilitated, and since the magnet6and the insertion hole7are in surface-to-surface contact with each other, adhesion and fixation can be made strongly and stably. Further, since the circumferential-direction-side end surfaces93of each magnet6are in contact with the first projection82and the second projection83, the position of the magnet6is stabilized.

At this time, the magnet inner side peripheral surface91of each magnet6and the hole inner side peripheral surface81of each insertion hole7are not in contact with each other, and a space is provided between the magnet inner side peripheral surface91of each magnet6and the hole inner side peripheral surface81of each insertion hole7, whereby the first gap portion51and the second gap portion52are formed.

Next, a method for assembling the rotating electric machine1using the rotor3manufactured as described above will be described. For the stator2, electromagnetic steel sheets as a main material are stamped to form the stator core20. It is noted that the method for forming the stator core20is not limited to stamping of electromagnetic steel sheets. Next, the coil21assembled in an annular shape, to which an insulation sheet is attached, is inserted into the stator core20. It is noted that the method for assembling the coil21and the stator core20is not limited to the above method. Next, the shaft4is fixed to the rotor core30of the rotor3manufactured as described above. Next, the rotor3is inserted into the stator2with the air gap5therebetween, and thus they are assembled and the rotating electric machine1is manufactured. It is noted that, also in the other embodiments below, the rotating electric machine1can be configured in the same manner, and therefore the description and illustration thereof are omitted.

In embodiment 1 configured as described above, the rotor is configured such that, the hole inner side peripheral surface of each insertion hole and the magnet inner side peripheral surface of each magnet are not in contact with each other so that a space is formed therebetween, an adhesion layer portion is formed between the hole outer side peripheral surface of each insertion hole and the magnet outer side peripheral surface of each magnet, the hole outer side peripheral surface of each insertion hole and the magnet outer side peripheral surface of each magnet with which the adhesion layer portion contacts are formed in a flat-surface shape, the width in the radial direction of the space between each insertion hole and each magnet is longer than the width in the radial direction of the adhesion layer portion. In addition, the rotating electric machine is provided with the rotor, a rotary shaft for rotating the rotor core, and a stator having a coil and located with an air gap from the rotor. In the above rotor and rotating electric machine, reduction of torque performance can be suppressed and the magnets can be stably held.

Specifically,FIG. 6shows a magnet usage rate of a rotor in a comparative example in which the width in the radial direction of the space between the hole inner side peripheral surface of each insertion hole and the magnet inner side peripheral surface of each magnet is shorter than the width in the radial direction of the adhesion layer portion between the hole outer side peripheral surface of each insertion hole and the magnet outer side peripheral surface of each magnet, and a magnet usage rate of the rotor corresponding to the invention of the present application, in which the width in the radial direction of the space between the hole inner side peripheral surface of each insertion hole and the magnet inner side peripheral surface of each magnet is longer than the width in the radial direction of the adhesion layer portion between the hole outer side peripheral surface of each insertion hole and the magnet outer side peripheral surface of each magnet. Calculations of both magnet usage rates were performed under the same condition. This time, the magnitude of torque per unit area of magnet, which serves as an index of torque, is shown as the result of magnet usage rates. As is obvious fromFIG. 6, it is found that the magnet usage rate in the present invention is greater than in the comparative example. Thus, it has been confirmed that reduction of the magnet usage rate is suppressed by the present invention.

Each magnet is formed such that the width in the radial direction on a side near the magnetic pole center axis of the insertion hole is longer than the width in the radial direction on a side far from the magnetic pole center axis of the insertion hole. Therefore, the salient pole ratio of the magnet can be increased, and a difference between a q-axis inductance Lq and a d-axis inductance Ld for generating torque is increased, whereby torque can be increased.

The first projection projecting outward in the radial direction is formed on the hole inner side peripheral surface of each insertion hole. This first projection is formed in contact with the circumferential-direction-side end surface of the magnet. Therefore, during rotation of the rotor, even if the magnet comes off, since the magnet is in contact with the first projection, concentration of stress applied to the rotor core can be relaxed and positional accuracy can be improved. Further, variation among directions of the magnetic fluxes due to position deviation of magnets can be reduced.

In the insertion holes divided by the bridge portion, the magnets are arranged symmetrically between left and right with respect to the magnetic pole center axis of the insertion holes. Therefore, even if parallel orientation is performed instead of radial orientation, the orientation can be concentrated on the center of the magnetic pole. Here, the radial orientation refers to that a magnet is molded with an orientation magnetic field applied radially during magnetic field application in a magnet molding step, and the parallel orientation refers to that a magnet is molded with an orientation magnetic field applied in parallel during magnetic field application in a magnet molding step. In the case of adjusting the orientation magnetic field uniformly, the adjustment can be performed more easily by the parallel orientation than by the radial orientation.

The second projection which projects toward the magnet side in each insertion hole and contacts with the magnet is formed on the bridge portion between the insertion holes divided by the bridge portion. Therefore, during rotation of the rotor, even if the magnet comes off, since the magnet is in contact with the second projection, concentration of stress applied to the rotor core can be relaxed and positional accuracy can be improved. Further, variation among directions of the magnetic fluxes due to position deviation of magnets can be reduced.

The hole circumferential-direction-side end surface of each insertion hole is formed in an arc shape. Therefore, concentration of stress applied to the rotor core part other than the insertion holes during rotation of the rotor can be relaxed.

The insertion holes are formed in a plurality of layers in the radial direction. Therefore, it is possible to adapt to various magnet arrangements.

The flux barrier portions are formed on both end sides of the insertion holes and the magnets. Therefore, leakage of a magnetic flux when the rotating electric machine is operated can be reduced.

In the present embodiment, the case where the magnets and the insertion holes are arranged one by one symmetrically between left and right with respect to the magnetic pole center axis has been shown as an example. However, without limitation thereto, the numbers of the magnets and the insertion holes to be arranged on each side may be two or more as long as they are arranged symmetrically between left and right with respect to the magnetic pole center axis, and even in such a case, the same configuration can be applied and the same effect can be provided.

FIG. 7is a plan view showing the structure of a rotor according to embodiment 2 of the present invention.FIG. 8is a partially enlarged plan view showing the structure of a ⅛ model of the rotor shown inFIG. 7.FIG. 9is a partially enlarged plan view showing the structure of half of the rotor shown inFIG. 8.FIG. 10shows magnet usage rates of a rotating electric machine of the present invention and a rotating electric machine of a comparative example. Only inFIG. 8, hatching is applied for the purpose of understanding structures. In the other figures, the same structures are shown and therefore hatching is omitted.

In the drawings, the same parts as in the above embodiment 1 are denoted by the same reference characters and the description thereof is omitted. In the present embodiment 2, angles θ1and θ2between the circumferential-direction-side end surfaces93and the magnet outer side peripheral surface90of each magnet6are set to 90 degrees. The other configuration is the same as in the above embodiment 1, and manufacturing can be performed in the same manner.

In embodiment 2 configured as described above, the same effects as in the above embodiment 1 are provided, and further, the following effects are provided. Since the angles between the magnet outer side peripheral surface of each magnet and the circumferential-direction-side end surfaces of the magnet are set to 90 degrees, it becomes easy to hold both circumferential-direction-side end surfaces of the magnet, whereby insertion of the magnet into the insertion hole can be facilitated and positional accuracy of the magnet at the time of insertion can be improved.FIG. 10shows a magnet usage rate in the case where the angles between the magnet outer side peripheral surface of each magnet and the circumferential-direction-side end surfaces of the magnet are set to 90 degrees in the present invention, and a magnet usage rate in the case where the angles are set to different degrees as a comparative example. Calculations of both magnet usage rates were performed under the same condition. As is obvious fromFIG. 10, it is found that the magnet usage rate in the present invention is greater than in the comparative example. Thus, it has been confirmed that reduction of the magnet usage rate is suppressed by the present invention.

FIG. 11is a plan view showing the structure of a rotor according to embodiment 3 of the present invention.FIG. 12is a partially enlarged plan view showing the structure of a ⅛ model of the rotor shown inFIG. 11.FIG. 13is a partially enlarged plan view showing the structure of half of the rotor shown inFIG. 11.FIG. 14shows magnet usage rates of a rotating electric machine of the present invention and a rotating electric machine of a comparative example. Only inFIG. 12, hatching is applied for the purpose of understanding structures. In the other figures, the same structures are shown and therefore hatching is omitted.

In the drawings, the same parts as in the above embodiments are denoted by the same reference characters and the description thereof is omitted. In the present embodiment 3, the case where the insertion holes7are formed in only one layer in the radial direction X is shown as an example. The other configuration is the same as in the above embodiments, and manufacturing can be performed in the same manner.

In embodiment 3 configured as described above, the same effects as in the above embodiments are provided. Specifically,FIG. 14shows a magnet usage rate of a rotor in a comparative example in which the insertion holes are formed in only one layer in the radial direction, the width in the radial direction of the space between the hole inner side peripheral surface of each insertion hole and the magnet inner side peripheral surface of each magnet is shorter than the width in the radial direction of the adhesion layer portion between the hole outer side peripheral surface of each insertion hole and the magnet outer side peripheral surface of each magnet, and a magnet usage rate of the rotor corresponding to the invention of the present application, in which the width in the radial direction of the space between the hole inner side peripheral surface of each insertion hole and the magnet inner side peripheral surface of each magnet is longer than the width in the radial direction of the adhesion layer portion between the hole outer side peripheral surface of each insertion hole and the magnet outer side peripheral surface of each magnet. Calculations of both magnet usage rates were performed under the same condition. As is obvious fromFIG. 14, it is found that the magnet usage rate in the present invention is greater than in the comparative example. Thus, it has been confirmed that reduction of the magnet usage rate is suppressed by the present invention.

FIG. 15is a plan view showing the structure of a rotor according to embodiment 4 of the present invention.FIG. 16is a partially enlarged plan view showing the structure of a ⅛ model of the rotor shown inFIG. 15.FIG. 17is a partially enlarged plan view showing the structure of half of the rotor shown inFIG. 16. Only inFIG. 16, hatching is applied for the purpose of understanding structures. In the other figures, the same structures are shown and therefore hatching is omitted.

In the drawings, the same parts as in the above embodiments are denoted by the same reference characters and the description thereof is omitted. In the present embodiment 4, the case where the insertion holes7are formed in three layers in the radial direction X is shown as an example. The other configuration is the same as in the above embodiments, and manufacturing can be performed in the same manner. The insertion holes7include three layers of the first insertion hole71, the second insertion hole72, and a third insertion hole73. In the third insertion hole73, a third bridge portion43is formed on the magnetic pole center axis, and thus the third insertion hole73is divided into a third insertion hole73A and a third insertion hole73B having shapes line-symmetric between left and right with respect to the center axis.

A third magnet63A and a third magnet63B are respectively inserted in the third insertion hole73A and the third insertion hole73B. Therefore, third magnets63are composed of the third magnet63A and the third magnet63B. As shown inFIG. 17, a third adhesion layer portion13is formed between a hole outer side peripheral surface80of the third insertion hole73and a magnet outer side peripheral surface90of the third magnet63, thereby fixing them. Each hole outer side peripheral surface80at which the third adhesion layer portion13is formed and which is a side surface in the circumferential direction Z on the outer side in the radial direction X of the third insertion hole73, is formed in a flat-surface shape. Each magnet outer side peripheral surface90at which the third adhesion layer portion13is formed and which is a surface in the circumferential direction Z on the outer side in the radial direction X of the third magnet63, is formed in a flat-surface shape.

A hole inner side peripheral surface81which is a side surface in the circumferential direction Z on the inner side in the radial direction X of each third insertion hole73, is formed in an arc-surface shape that is convex inward in the radial direction X of the rotor3. A magnet inner side peripheral surface91which is a surface in the circumferential direction Z on the inner side in the radial direction X of each third magnet63, is formed in an arc-surface shape that is convex inward in the radial direction X of the rotor3.

The hole inner side peripheral surface81of the third insertion hole73and the magnet inner side peripheral surface91of the third magnet63are not in contact with each other and a space is provided therebetween to form a third gap portion53. A width T5in the radial direction X of the third gap portion53is longer than a width T6in the radial direction X of the third adhesion layer portion13. Specifically, the width T6is about 0.03 mm to 0.15 mm. The width T5is longer than the width T6but is about 1 mm or less.

On the hole inner side peripheral surface81of each third insertion hole73A,73B, a first projection82is formed which projects outward in the radial direction X and contacts with a circumferential-direction-side end surface93of each third magnet63A,63B on a side opposite to the third bridge portion43side in the circumferential direction Z. On the third bridge portion43between the third insertion holes73, a second projection83is formed which projects toward the third magnet63side in each third insertion hole73and contacts with each third magnet63. Each projection82,83serves as a contact stopper for preventing the third magnet63inserted in the third insertion hole73from moving during rotation of the rotor core30.

Hole circumferential-direction-side end surfaces84of the third insertion holes73A,73B are formed in an arc shape. In the third insertion holes73A,73B, there are spaces where the third magnets63A,63B are not present, and these spaces serve as flux barrier portions8.

In embodiment 4 configured as described above, the same effects as in the above embodiments are provided, and further, since the insertion holes and the magnets are arranged in three layers, magnet torque generated by a magnetomotive force of the magnets can be increased.

It is noted that, within the scope of the present invention, the above embodiments may be freely combined with each other, or each of the above embodiments may be modified or simplified as appropriate.