CN115995897A - Magnet embedded motor - Google Patents

Abstract

The invention provides a magnet embedded motor, which can restrain the reduction of effective magnetic flux caused by leakage magnetic flux and can facilitate the assembly of a rotor. A rotor (30) of a magnet-embedded motor (1) is provided with a plurality of magnets (33) arranged at equal angular intervals and a rotor core (32) in which the magnets (33) are embedded. A rotor core (32) is provided with: a slit (35) in which a magnet (33) is disposed; magnetic pole parts (34) located between circumferentially adjacent slits (35); and an inner connection part (37) which connects the circumferentially adjacent magnetic pole parts (34) to the radially inner side of the slit (35). A step (43) extending toward the center of the slit (35) in the circumferential direction is provided on at least one side edge (41, 42) in the circumferential direction of the slit (35). The magnet (33) is in contact with the step (43) from the radial outside, and a first gap (51) is provided between the magnet (33) and the inside connecting portion (37).

Description

Magnet embedded motor

Technical Field

The present invention relates to a magnet embedded motor including a rotor in which a plurality of magnets are embedded in a rotor core made of a magnetic material.

Background

As a rotor of the magnet embedded motor, a rotor is used in which a plurality of slits are formed in a rotor core so as to be radially arranged, and a magnet is embedded in each of the plurality of slits. Such a magnet embedded motor is disclosed in patent documents 1 and 2.

The rotary electric machines (magnet embedded motors) of patent documents 1 and 2 are inner rotor type motors in which a rotor is disposed on the inner peripheral side of a stator, and a rotor core is formed by laminating a plurality of steel plates. The rotor core includes a plurality of magnetic pole portions arranged at equal angular intervals in the circumferential direction, and magnets are embedded in slits provided between circumferentially adjacent magnetic pole portions. Further, punched holes are formed at the inner peripheral end of each magnetic pole portion. Therefore, gaps functioning as flux barriers are provided on both circumferential sides of the inner circumferential end of each magnet.

In the rotor of patent document 1, the magnets extend to an end portion provided on the inner peripheral side of the slit of the rotor core. On the other hand, in the rotor of patent document 2, the radial length of the magnet is shorter than the radial length of the slit, and the magnet is disposed so as to be offset to the end portion on the outer peripheral side of the slit. Therefore, a gap is formed between the end surface of the inner periphery side of the magnet and the edge of the inner periphery side of the slit.

Prior art literature

Patent literature

Patent document 1: japanese patent No. 5057171

Patent document 2: japanese patent No. 6673707

Disclosure of Invention

As in patent document 2, when the punched holes are formed not only on both sides of the magnet in the circumferential direction but also on the inner circumferential side of the magnet, leakage magnetic flux around the inner circumferential side of the magnet can be reduced. Therefore, the magnetic flux that can be effectively used can be increased, and the motor torque can be increased. In addition, by shortening the radial length of the magnet, the amount of the magnet used can be reduced. Therefore, the component cost can be reduced.

However, in patent document 2, the magnet and the slit are formed in a shape in which the magnet can slide in the radial direction in the slit. Therefore, when the magnetized magnet is assembled to the rotor core, the magnet is attracted to the inner peripheral side, and it is difficult to position the magnet at the end portion of the slit on the outer peripheral side. Although the magnet may be positioned on the outer peripheral side by sandwiching the nonmagnetic member on the inner peripheral side of the magnet, there is a problem in that the number of members increases and the number of assembly man-hours increases.

In view of the above, an object of the present invention is to reduce leakage magnetic flux around the inner periphery of a magnet in a magnet-embedded motor, to increase motor torque, and to facilitate assembly of a rotor.

In order to solve the above problems, a magnet embedded motor according to the present invention includes: a rotor including a plurality of magnets arranged at equal angular intervals and a rotor core in which the magnets are embedded; and a stator including a plurality of salient poles arranged at equal angular intervals on an outer peripheral side of the rotor and wound with coils, wherein the rotor core includes: a slit in which the magnet is disposed; magnetic pole parts positioned between circumferentially adjacent slits; and an inner connecting portion connecting circumferentially adjacent magnetic pole portions to the radially inner side of the slit, wherein a step portion extending toward the center of the slit in the circumferential direction is provided on at least one side edge in the circumferential direction of the slit, the magnet is abutted against the step portion from the radially outer side, and a first gap is provided between the magnet and the inner connecting portion.

According to the present invention, a stepped portion is provided on a circumferential side edge of a slit provided in a rotor core, and a magnet is abutted against the stepped portion from a radially outer side. Therefore, when the rotor is assembled, the magnets arranged in the slits can be positioned in contact with the stepped portions, and therefore the magnetized magnets can be prevented from being attracted to the inner peripheral side. Thus, the rotor having the first gap provided on the inner peripheral side of the magnet can be easily assembled. Further, by providing the first gap, leakage magnetic flux around the inner periphery of the magnet can be reduced. Therefore, the reduction of the effective magnetic flux interlinked with the stator can be suppressed, and thus the motor torque can be increased.

In addition, according to the present invention, since the magnet can be positioned by abutting against the step portion, it is not necessary to use a non-magnetic member for securing the first gap. Therefore, an increase in the number of components and an increase in the number of assembly man-hours can be suppressed. Further, since the portion where the first gap is provided can shorten the radial length of the magnet, the magnet can be miniaturized, and the component cost can be reduced.

In the present invention, it is preferable that the step portions are provided at side edges on both sides in the circumferential direction of the slit. Thus, since both ends in the circumferential direction of the magnet are in contact with the stepped portions, the magnet can be prevented from being inclined. This can improve the positional accuracy of the magnet.

In the present invention, it is preferable that the magnetic pole portion includes a hole portion that forms a second gap, and at least a part of the second gap is located radially outward of the step portion. Thus, the magnetic flux does not easily pass through the region where the second gap is provided. Therefore, the leakage flux that bypasses from both sides in the circumferential direction of the magnet to the inner circumferential side can be reduced, and thus the reduction of the effective magnetic flux can be suppressed.

In the present invention, the hole preferably includes: a side edge portion surrounding one side of the second gap in the circumferential direction; and another side edge portion surrounding another side of the second gap in a circumferential direction, the one side edge portion and the another side edge portion each including: a first linear portion extending substantially parallel to a circumferential side edge of the magnet; and a second linear portion that is connected to a radially outer end of the first linear portion and that is inclined in a direction away from the magnet as it goes radially outward, wherein the step portion is located radially inward of a bending point connecting the first linear portion and the second linear portion. Thus, the width of the portion between the first linear portion of the magnetic pole portion and the side surface of the magnet is narrowed, and a thin portion is formed. Therefore, the magnetic flux does not easily pass through both sides in the circumferential direction of the magnet, and thus leakage magnetic flux can be reduced. Further, the magnetic flux is directed to the outer peripheral side along the inclined surface (second straight line portion) on the radially outer side of the first straight line portion. Therefore, the effective magnetic flux can be increased.

In the present invention, it is preferable that the rotor core includes a magnetic pole portion inner peripheral portion extending in a circumferential direction radially inward of the hole portion, and a radial width of the magnetic pole portion inner peripheral portion is substantially equal to a radial width of the inner connecting portion. In this way, if the radial width of the inner peripheral portion of the rotor core is uniform, the stress caused by expansion and contraction of the metal can be equalized when the rotor core is fixed to the rotating shaft by the press-fitting.

In the present invention, it is preferable that the rotor core includes an outer connecting portion that connects the magnetic pole portions adjacent to each other in the circumferential direction on the outer side in the radial direction of the slit, and that an end surface of the magnet on the outer side in the radial direction is in contact with the outer connecting portion. In this way, the magnet can be positioned with high accuracy.

Effects of the invention

According to the present invention, a stepped portion is provided on a circumferential side edge of a slit provided in a rotor core, and a magnet is abutted against the stepped portion from a radially outer side. Therefore, when the rotor is assembled, the magnet disposed in the slit can be easily positioned by abutting against the step portion, and therefore the magnetized magnet can be prevented from being attracted to the inner peripheral side. Thus, the rotor having the first gap provided on the inner peripheral side of the magnet can be easily assembled. Further, by providing the first gap, leakage magnetic flux around the inner periphery of the magnet can be reduced. Therefore, the reduction of the effective magnetic flux interlinked with the stator can be suppressed, and thus the motor torque can be increased.

Drawings

Fig. 1 is a cross-sectional view of a magnet embedded motor according to the present invention taken along a plane including a rotation axis, and a cross-sectional view of a rotor and a stator core taken along a plane orthogonal to the rotation axis.

Fig. 2 is a cross-sectional view of the rotor taken in a plane orthogonal to the axis of rotation.

Fig. 3 is an enlarged partial cross-sectional view of the rotor.

Fig. 4 is an enlarged view of the outer connecting portion.

Detailed Description

Hereinafter, a magnet embedded motor to which the present invention is applied will be described with reference to the drawings. Fig. 1 (a) is a cross-sectional view of the magnet embedded motor 1 of the present invention taken along a plane including the rotation axis L. Fig. 1 (b) is a cross-sectional view of the rotor 30 and the stator core 21 taken along a plane orthogonal to the rotation axis L. In the present specification, the direction in which the rotation axis L of the magnet embedded motor 1 extends is referred to as the rotation axis direction, one side in the rotation axis direction (the side from which the output shaft 2 protrudes) is referred to as the output side L1, and the other side in the rotation axis direction (the side opposite to the side from which the output shaft 2 protrudes) is referred to as the counter output side L2.

(integral structure)

As shown in fig. 1 a and 1 b, the magnet embedded motor 1 (hereinafter simply referred to as a motor 1) includes a motor case 10, a cylindrical stator 20 disposed inside the motor case 10, and a rotor 30 rotatably disposed inside the stator 20. The motor housing 10 includes: a cylindrical portion 11 that opens in the direction of the rotation axis of the motor 1; a first bearing holder 12 fixed to an end of the output side L1 of the cylindrical portion 11; and a second bearing holder 13 fixed to an end of the cylindrical portion 11 on the opposite output side L2. An outer race of the first bearing 14 constituted by a ball bearing is held in the inner portion Zhou Cebao of the first bearing holder 12. Further, an outer ring of the second bearing 15 constituted by a ball bearing is held in the inner portion Zhou Cebao of the second bearing holder 13. An unshown encoder cover is attached to the opposite output side L2 of the second bearing holder 13, and an unshown encoder is disposed inside the encoder cover. The encoder detects the rotational speed and angular position of the rotor 30.

The stator 20 has: an annular stator core 21 having a plurality of salient poles 24 protruding radially inward at equal angular intervals; and a coil 23 wound around each salient pole 24 of the stator core 21 via an insulating member 22, and the stator 20 is fixed to the inside of the cylindrical portion 11. The coil 23 is connected to a wiring board, not shown, disposed at an end of the stator core 21. A power supply line is connected to the wiring board, and power is supplied to the coil 23 via the power supply line and the wiring board.

The rotor 30 is rotatably disposed inside the stator 20. The rotor 30 includes a rotary shaft 31 extending in the rotation axis direction of the motor 1, a rotor core 32 fixed to the outer peripheral side of the rotary shaft 31, and a magnet 33 embedded in the rotor core 32. The rotation shaft 31 protrudes toward the output side L1 and the counter output side L2 of the rotor core 32. An output shaft 2 protruding from the first bearing holder 12 is provided at an end of the output side L1 of the rotary shaft 31.

The rotor core 32 is a laminated body formed by laminating a plurality of plates (magnetic plates) of a magnetic material such as a silicon steel plate. As shown in fig. 1 (b), a plurality of magnets 33 are embedded in the rotor core 32 in a radial arrangement. A plurality of salient poles 24 protruding toward the rotor core 32 are radially arranged on the outer peripheral side of the rotor core 32. The magnets 33 and the salient poles 24 are arranged at equal angular intervals. In the present embodiment, the number of magnets 33 embedded in the rotor core 32 is 10, and the number of salient poles 24 provided in the stator 20 is 12, so that the motor 1 is a 10-pole 12-slot motor. Three-phase currents of U-phase, V-phase, and W-phase are supplied to the coils 23 wound around the salient poles 24. The number of poles of the rotor 30 may be two or more, and the number of salient poles 24 may be other than 12.

(rotor core)

Fig. 2 is a cross-sectional view of the rotor 30 taken in a plane orthogonal to the rotation axis L, and fig. 3 is a partial enlarged cross-sectional view of the rotor 30. As shown in fig. 1 (b) and 2, in the rotor core 32, a portion between circumferentially adjacent magnets 33 becomes a magnetic pole portion 34. A plurality of slits 35 are formed in the rotor core 32 at equal angular intervals, and the magnets 33 are embedded in the slits 35. The rotor core 32 further includes: an outer connecting portion 36 that connects the circumferentially adjacent magnetic pole portions 34 and is located radially outward of the slit 35 and the magnet 33; and an inner connecting portion 37 that connects the circumferentially adjacent magnetic pole portions 34 and is located radially inward of the slit 35 and the magnet 33.

The magnetic pole 34 has a punched hole 38 formed at a position adjacent to the radially inner end of the slit 35 in the circumferential direction. The magnetic pole 34 includes a magnetic pole inner peripheral portion 39 located radially inward of the punched hole 38. The magnetic pole inner peripheral portion 39 and the inner connecting portion 37 constitute an inner peripheral portion of the rotor core 32, and surround the rotary shaft 31 fixed to the center of the rotor core 32. The rotor core 32 is fixed to the rotary shaft 31 by a press fit.

The slits 35 and the punched holes 38 are formed by punching out the rotor core 32 in the rotation axis direction. The slits 35 extend radially and the punched holes 38 are hexagonal. The slit 35 and the punched hole 38 are open at the end face in the rotation axis direction of the rotor core 32.

The rotor 30 is provided with 3 gaps functioning as flux barriers. Each magnet 33 is buried in a position where a radial gap (first gap 51) is provided between the magnet and the inner connecting portion 37 disposed radially inward of the slit 35. In addition, punched holes 38 (hole portions) provided in the respective magnetic pole portions 34 form second gaps 52. A third gap 53 is provided between the radially outer end of each slit 35 and the circumferential side surface of the magnet 33.

(shape of slit)

The radial dimension of the slit 35 is longer than the radial dimension of the magnet 33, and the magnet 33 is buried in a position offset from the radially outer end of the slit 35. As shown in fig. 3, each slit 35 includes a magnet housing portion 351 into which the magnet 33 is fitted, and a distal end portion 352 extending radially inward from the magnet housing portion 351. The front end portion 352 has a circumferential width smaller than that of the magnet housing portion 351, and the front end portion 352 is located at a circumferential center of the magnet housing portion 351. The magnet housing portion 351 includes a wide portion 353 provided at an end portion radially outward. The magnet housing portion 351 has a constant circumferential width except for the wide portion 353.

The side edge 41 of one side in the circumferential direction of the slit 35 and the side edge 42 of the other side in the circumferential direction of the slit 35 each include a step portion 43 connecting the side edge in the circumferential direction of the magnet housing portion 351 and the side edge in the circumferential direction of the distal end portion 352. The step portion 43 extends from the radially inner end of the magnet housing portion 351 toward the circumferential center of the slit 35. In the present embodiment, the dimension D of the step 43 in the circumferential direction is 0.5mm. Further, recesses 44 are provided in the circumferential side edges 41 and 42 of the slit 35 at the radially outer ends of the magnet housing 351, respectively, and the portions where the recesses 44 are provided are wide portions 353.

The magnet 33 is formed in a plate shape having a constant thickness, and is embedded so that the circumferential end surface thereof contacts the circumferential side edges 41 and 42 of the slit 35. The magnet 33 is magnetized so that the end face facing one side and the end face facing the other side have different polarities. In addition, the poles of the circumferentially adjacent magnets 33 are reversed, and the poles of the same polarity are circumferentially opposite to each other.

The radially outer end surface of the magnet 33 contacts the outer connecting portion 36. On the other hand, the radially inner end surface of the magnet 33 is in contact with the stepped portions 43 provided on the circumferential side edges 41 and 42 of the slit 35 from the radially outer side. Thereby, the magnet 33 is positioned at a position separated from the inner connecting portion 37 located on the inner peripheral side of the slit 35 in the radial direction, and the first gap 51 is formed between the magnet 33 and the inner connecting portion 37.

By providing the first gap 51 between the magnet 33 and the inner connecting portion 37, leakage magnetic flux that bypasses radially inward of the magnet 33 can be reduced. The present inventors studied the presence or absence of the first gap 51 and the increase or decrease of the effective magnetic flux interlinked with the stator 20 by magnetic field analysis. As a result, when the radial dimension H of the first space 51 is about 1mm, a larger amount of effective magnetic flux is obtained than when the first space 51 is not provided (that is, when the tip end portion 352 is not provided in the slit 35).

In contrast to the wide portion 353 provided at the radially outer end of the magnet housing portion 351, the magnet 33 has a constant circumferential thickness, and therefore the inner surface of the wide portion 353 (i.e., the inner surface of the recess 44) is separated from the circumferential side surface of the magnet 33. Therefore, the third gaps 53 are provided on both sides in the circumferential direction of the radially outer end portion of the magnet 33. The third gap 53 is disposed on the outer peripheral portion of the rotor core 32 and on the inner peripheral side of the outer connecting portion 36 connecting the adjacent magnetic pole portions 34. By providing the third gap 53 at such a position, the influence of the magnetic field from the stator 20 side can be reduced, and demagnetization of the magnet 33 can be made less likely to occur. The outer connecting portion 36 is formed with a third gap 53, and the length in the circumferential direction thereof is longer than the thickness in the circumferential direction of the magnet 33 by the width of the third gap 53.

(punching shape)

The punched holes 38 formed in the magnetic pole portions 34 of the rotor core 32 are hexagonal and are formed in a shape symmetrical in the circumferential direction with reference to a reference line P (see fig. 2) extending radially through the circumferential center of the magnetic pole portions 34. As shown in fig. 3, each punched hole 38 includes: a side edge portion 61 surrounding one side in the circumferential direction of the second void 52; the other side edge portion 62 surrounding the other side in the circumferential direction of the second void 52; an outer peripheral side edge 63 surrounding the second void 52 on the radially outer side; and an inner peripheral side edge portion 64 surrounding the radially inner side of the second void 52.

The one side edge 61 and the other side edge 62 are each bent at a bending point Q at substantially the center in the radial direction. The one side edge portion 61 and the other side edge portion 62 each include a first straight portion 65 extending linearly from the end of the inner peripheral side edge portion 64 to the bending point Q and a second straight portion 66 extending linearly from the bending point Q to the end of the outer peripheral side edge portion 63. Slits 35 are formed on both sides of the punched hole 38 in the circumferential direction, and magnets 33 are arranged. The first linear portion 65 extends substantially parallel to the circumferential side edge of the magnet 33. On the other hand, the second linear portion 66 is inclined with respect to the first linear portion 65, and extends in a direction away from the side edge of the magnet 33 in the circumferential direction as going radially outward.

The inner peripheral edge 64 of the punched hole 38 is located radially inward of the step 43 of the slit 35, and the outer peripheral edge 63 is located radially outward of the step 43. Therefore, the second gap 52 extends from a position radially inward of the stepped portion 43 to a position radially outward of the stepped portion 43. More specifically, in the present embodiment, the bending point Q of the one edge 61 and the other edge 62 of the punched hole 38 is located radially outward of the step 43 of the slit 35. Therefore, a portion between the first straight portion 65 of the punched hole 38 and the circumferential side edge of the magnet housing portion 351 is a thin portion 67 having a substantially constant circumferential thickness. In the present embodiment, the thickness T of the thin portion 67 is 0.3mm.

The radially inner side of the magnet 33 is surrounded by the first gap 51, and both circumferential sides of the magnet 33 are surrounded by the thin wall portion 67 and the second gap 52. Therefore, the leakage flux that bypasses the magnet 33 radially inward can be reduced. On the other hand, a second linear portion 66 is provided radially outward of the thin portion 67, and the second linear portion 66 is inclined in a direction toward the circumferential center of the magnetic pole portion 34 as it goes radially outward. Therefore, the magnetic flux passing through the magnetic pole portion 34 is guided in the direction along the second linear portion 66 radially outward of the inflection point Q, and faces radially outward while facing the center of the magnetic pole portion 34 in the circumferential direction.

(outer peripheral surface shape of outer connecting portion)

Fig. 4 is an enlarged view of the outside connection portion 36. As shown in fig. 2, the rotor core 32 is substantially cylindrical as a whole, and the outer peripheral surface 341 of each magnetic pole portion 34 is an arc surface centered on the rotation axis L of the rotor core 32. On the other hand, as shown in fig. 4, the outer peripheral surface 361 connecting the outer connecting portions 36 of the adjacent magnetic pole portions 34 is located on the inner peripheral side of a virtual surface 362, which is an arc surface centered on the rotation axis L of the rotor core 32 and overlapping the outer peripheral surface 341.

The outer peripheral surface 361 of the outer connecting portion 36 has a convex shape protruding radially outward, and the distal end 363 protruding to the outermost peripheral side is located at the center in the circumferential direction of the outer peripheral surface 361. The outer peripheral surface 361 includes an inclined portion 364 that retreats from the front end 363 to the radially inner side and extends to both sides in the circumferential direction. The inclined portion 364 is a bent surface protruding toward the inner peripheral side of the rotor core 32. The outer peripheral surface 361 of the outer connecting portion 36 has the smallest radial thickness at both ends 365 in the circumferential direction, and gradually increases in radial thickness as it goes toward the tip end 363. Both circumferential ends 365 of the outer circumferential surface 361 are located radially outward of the third gap 53. The radial thickness of the outer connecting portion 36 is thinnest at the positions of the circumferential both ends 365, and the radial thickness of the outer connecting portion 36 at the both ends 365 is smaller than the thickness of the magnetic plate forming the rotor core 32. The reason for adopting such a shape is that the reverse voltage, cogging torque, and permeability coefficient of the motor 1 to be produced are measured, and as a result of performing magnetic field analysis, an increase in permeability coefficient and an improvement in cogging torque are found.

(main effects of the present embodiment)

The motor 1 of the present embodiment includes: a rotor 30 having a plurality of magnets 33 arranged at equal angular intervals and a rotor core 32 in which the magnets 33 are embedded; a stator 20 having a plurality of salient poles 24 arranged at equal angular intervals on the outer peripheral side of the rotor 30 and around which coils 23 are wound. The rotor core 32 includes: a slit 35 in which the magnet 33 is disposed; magnetic pole portions 34 located between circumferentially adjacent slits 35; and an inner connecting portion 37 connecting the circumferentially adjacent magnetic pole portions 34 radially inward of the slit 35. The side edges 41 and 42 on both sides in the circumferential direction of the slit 35 are provided with step portions 43 extending toward the circumferential center of the slit 35. The magnet 33 is in contact with the stepped portion 43 from the radially outer side, and a first gap 51 is provided between the magnet 33 and the inner side connecting portion 37.

In the present embodiment, when assembling the rotor 30, the magnets 33 disposed in the slits 35 of the rotor core 32 are positioned in contact with the stepped portions 43 provided on the circumferential side edges 41 and 42 of the slits 35. This can prevent the magnetized magnet 33 from being attracted to the inner peripheral side, and therefore, the rotor 30 having the first gap 51 provided on the inner peripheral side of the magnet 33 can be easily assembled. Further, by providing the first gap 51, leakage magnetic flux around the inner periphery of the magnet 33 can be reduced. This suppresses a decrease in the effective magnetic flux interlinking with the stator 20, and thus increases the motor torque.

In the present embodiment, since the magnet 33 can be positioned in contact with the step 43, it is not necessary to use a separate nonmagnetic member for securing the first gap 51. Therefore, an increase in the number of components and an increase in the number of assembly man-hours can be suppressed. Further, since the portion where the first gap 51 is provided can shorten the length of the magnet 33 in the radial direction, the magnet 33 can be miniaturized, and the component cost can be reduced. The first gap 51 may be used as a space for filling an adhesive for fixing the magnet 33 to the rotor core 32.

The step 43 may be provided on at least one of the side edges 41 and 42 in the circumferential direction of the slit 35. In the structure in which the stepped portion 43 is provided only on one of the side edges 41, 42, the magnet 33 can be positioned in the radial direction.

In the present embodiment, the stepped portions 43 are provided on the side edges 41, 42 on both circumferential sides of the slit 35. Therefore, since both ends in the circumferential direction of the magnet 33 can be supported by the stepped portions 43, the magnet 33 can be prevented from tilting, and the positional accuracy of the magnet 33 can be improved. More specifically, the slit 35 of the present embodiment includes: the magnet 33 is fitted into the inner magnet housing 351; and a distal end portion 352 provided radially inward of the magnet housing portion 351 to form the first gap 51. The tip portion 352 has a circumferential width smaller than that of the magnet housing portion 351, and is disposed at a circumferential center of the magnet housing portion 351. The step 43 connects the circumferential side edges 41 and 42 of the magnet housing 351 with the circumferential side edges 41 and 42 of the distal end 352. Therefore, the first gap 51 is arranged at the center in the circumferential direction of the magnet 33, and therefore the distribution of the magnetic flux can be made uniform on both sides in the circumferential direction of the magnet 33.

In the present embodiment, the magnetic pole portion 34 of the rotor core 32 includes the punched hole 38 (hole portion) that forms the second void 52, and the second void 52 extends from a position radially outward of the step portion 43 to a position radially inward of the step portion 43. Therefore, since the first gap 51 is provided on the radially inner side of the magnet 33 and the second gaps 52 are provided on both sides in the circumferential direction of the radially inner end portion of the magnet 33, leakage magnetic flux that bypasses the inner circumferential side of the magnet 33 can be further reduced. Therefore, the decrease of the effective magnetic flux interlinking with the stator 20 can be suppressed.

The second gap 52 may be at least partially located radially outward of the stepped portion 43. In such a configuration, since the second gaps 52 are arranged on both sides in the circumferential direction of the magnet 33, leakage magnetic fluxes that pass around the inner circumferential side from both sides in the circumferential direction of the magnet 33 can be reduced.

In the present embodiment, the punched hole 38 (hole) provided in the magnetic pole portion 34 of the rotor core 32 includes one side edge portion 61 surrounding one circumferential side of the second gap 52 and the other side edge portion 62 surrounding the other circumferential side of the second gap 52. The one side edge portion 61 and the other side edge portion 62 each include a first linear portion 65 extending substantially parallel to the circumferential side edge of the magnet 33, and a second linear portion 66 connected to the radially outer end of the first linear portion 65 and inclined in a direction away from the magnet 33 as going radially outward. The stepped portion 43 is located radially inward of a bending point Q connecting the first straight line portion 65 and the second straight line portion 66. In this way, the thin portion 67 through which magnetic flux is difficult to pass is formed between the first linear portion 65 and the side surface of the magnet 33, so that leakage magnetic flux can be reduced. Further, since the inclined surface (second straight line portion) is provided radially outward of the bending point Q, the magnetic flux is directed toward the outer peripheral side along the inclined surface (second straight line portion). Therefore, the effective magnetic flux interlinking with the stator 20 can be increased.

In the present embodiment, the rotor core 32 includes a magnetic pole portion inner peripheral portion 39 extending in the circumferential direction inside the punched hole 38 (hole portion) in the radial direction. The radial dimension of the magnetic pole inner peripheral portion 39 is slightly larger than the radial dimension of the inner connecting portion 37, and the increase or decrease in the radial thickness of the inner peripheral portion of the rotor core 32 surrounding the rotary shaft 31 is small. Therefore, when the rotary shaft 31 is fixed to the rotor core 32 by the press-fit, a stress difference caused by expansion and contraction of the inner peripheral portion surrounding the rotary shaft 31 is small.

The radial width of the magnetic pole inner peripheral portion 39 may be substantially the same as the radial width of the inner connecting portion 37. In this way, when the rotary shaft 31 is fixed to the rotor core 32 by the press-fit, the stress generated by expansion and contraction of the inner peripheral portion surrounding the rotary shaft 31 can be equalized.

In the present embodiment, the rotor core 32 includes the outer connecting portion 36, the outer connecting portion 36 connects the magnetic pole portions 34 adjacent in the circumferential direction on the radially outer side of the slit 35, and the radially outer end surface of the magnet 33 contacts the outer connecting portion 36. Therefore, the inner peripheral end and the outer peripheral end of the magnet 33 are in contact with the stepped portion 43 and the outer connecting portion 36, respectively, and therefore the magnet 33 can be positioned with high accuracy.

Symbol description

1 a magnet embedded motor (motor), 2 an output shaft, 10 a motor housing, 11 a cylindrical portion, 12 a first bearing holder, 13 a second bearing holder, 14 a first bearing, 15 a second bearing, 20 a stator, 21 a stator core, 22 an insulating member, 23 coils, 24 salient poles, 30 a rotor, 31 a rotating shaft, 32 a rotor core, 33 a magnet, 34 a magnetic pole portion, 35 a slit, 36 an outside connection portion, 37 an inside connection portion, 38 a punched hole (hole portion), 39 a magnetic pole portion inner peripheral portion, circumferential side edges of 41, 42 slits, 43 a step portion, 44 a concave portion, 51 a first gap, 52 a second gap, 53 a third gap, 61 a side edge portion, 62 a side edge portion, 63 an outer peripheral side edge portion, 64 an inner peripheral side edge portion, 65 a first straight line portion, 66 a second straight line portion, 67 a thin wall portion, an outer peripheral surface of a magnetic pole portion 341, 351 a magnet housing portion, 352 a front end portion, 353 a wide width portion, an outer peripheral surface of 361 a virtual surface 363, a front end portion, 364 an inclined portion, both ends of an outer peripheral surface of 365 an outer connection portion, L rotation axis L1, L output side reverse-bent point Q2, Q2.

Claims (6)

1. A magnet embedded motor is characterized by comprising:

a rotor including a plurality of magnets arranged at equal angular intervals and a rotor core in which the magnets are embedded; and

a stator including a plurality of salient poles arranged at equal angular intervals on an outer peripheral side of the rotor and wound with coils,

the rotor core is provided with: a slit in which the magnet is disposed; magnetic pole parts positioned between circumferentially adjacent slits; and an inner connecting portion connecting circumferentially adjacent magnetic pole portions on a radially inner side of the slit,

a step part extending towards the center of the circumferential direction of the slit is arranged on at least one side edge of the circumferential direction of the slit,

the magnet is abutted against the step part from the radial outer side,

a first gap is provided between the magnet and the inner connecting portion.

2. The embedded magnet motor according to claim 1, wherein,

the step portions are provided on side edges of both circumferential sides of the slit.

3. A magnet embedded motor according to claim 1 or 2, wherein,

the magnetic pole part is provided with a hole part for forming a second gap,

at least a part of the second gap is located radially outward of the step.

4. A magnet embedded motor according to claim 3, wherein,

the hole portion includes: a side edge portion surrounding one side of the second gap in the circumferential direction; and another side edge portion surrounding another side of the second gap in the circumferential direction,

the one side edge portion and the other side edge portion are respectively provided with: a first linear portion extending substantially parallel to a circumferential side edge of the magnet; and a second linear portion connected to a radially outer end of the first linear portion and inclined in a direction away from the magnet as going radially outward,

the step portion is located radially inward of a bending point at which the first straight portion and the second straight portion are connected.

5. A magnet embedded motor according to claim 3 or 4, wherein,

the rotor core includes a magnetic pole portion inner peripheral portion extending in a circumferential direction on a radially inner side of the hole portion,

the radial width of the inner peripheral portion of the magnetic pole portion is substantially the same as the radial width of the inner connecting portion.

6. The embedded magnet motor according to any one of claims 1 to 5, wherein,

the rotor core includes an outer connecting portion connecting the circumferentially adjacent magnetic pole portions radially outside the slit,

an end surface of the magnet on the radially outer side is in contact with the outer side connecting portion.

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