JP6336711B2 - Electric motor - Google Patents

Description

  The present invention relates to an electric motor, and more particularly to an improvement in a permanent magnet fixing structure used in a rotor of an embedded permanent magnet type synchronous motor.

  Conventionally, in a rotor of an embedded permanent magnet type synchronous motor, a permanent magnet is inserted into a plurality of holes provided in a rotor core, and an adhesive is applied to a gap formed between the outer surface of the permanent magnet and the inner surface of the hole. It is known to fill and thus fix the permanent magnet to the rotor core (see, for example, Patent Documents 1 and 2).

JP 2007-236020 A JP 2009-303445 A

  However, conventionally, since the adhesive is filled in a wide range between the outer surface of the permanent magnet and the inner surface of the hole portion, there is a problem that the filling work is troublesome. In particular, in Patent Document 1, even the flux barrier provided continuously in the hole is filled with the adhesive, so that the filling work takes an extra time and the workability is poor.

  Moreover, conventionally, an adhesive is filled in a gap formed at a position on the inner peripheral side of the rotor core among the gaps between the hole and the permanent magnet. By doing so, the permanent magnet is pushed to the outer peripheral side of the rotor core and brought into contact with the inner surface of the hole located on the outer peripheral side of the rotor core. For this reason, no gap is formed on the outer peripheral side, and the adhesive does not rotate. Therefore, the adhesive is mainly filled in the gap formed at the position on the inner peripheral side, but if a situation where the gap is not sufficiently filled occurs, the fixing strength of the permanent magnet is remarkably lowered. When a large centrifugal force generated during high load and high rotation is repeatedly applied, the permanent magnet may fall off in the hole.

Further, since the conventional configuration is such that the adhesive is pumped and filled, there is a problem that the equipment becomes expensive, such as a pump for pumping is required.
Furthermore, in Patent Documents 1 and 2, there is no mention of cooling of permanent magnets or rotor cores, which may lead to insufficient cooling.

  An object of the present invention is to provide an electric motor that can facilitate the filling operation of an adhesive and can reliably hold a permanent magnet.

  An electric motor according to a first aspect of the present invention includes an annular stator mounted in a housing, a rotor disposed in the stator and rotatably supported by the housing, and a plurality of permanent magnets in a rotor core of the rotor. Embedded in the rotor core, the rotor core is provided with embedded holes into which the permanent magnets are fitted, and the permanent magnets in the embedded holes are diagonally positioned in the axial direction of the rotor core. A continuous filling hole is formed along the surface.

  In the electric motor according to the second aspect of the present invention, it is desirable that the rotor core is provided with a flux barrier by an end portion of the embedded hole, and the flux barrier is an oil passage through which cooling oil flows.

  In the electric motor according to the third aspect of the invention, it is preferable that a flux barrier is provided on the rotor core by an end portion of the embedded hole, and a support portion that supports the permanent magnet is provided on the flux barrier.

  In the electric motor according to the fourth aspect of the present invention, it is preferable that the support portion is provided on the opposite side of the filling hole across the corner portion of the permanent magnet having a prismatic shape.

  An electric motor according to a fifth aspect of the present invention includes an annular stator mounted in a housing, and a rotor disposed in the stator and rotatably supported by the housing. The rotor core of the rotor has a plurality of rectangular cross sections. An electric motor in which a permanent magnet having a shape is embedded, and one magnetic pole is formed by a pair of the permanent magnets arranged in a V shape when viewed from the axial center of the rotor, and the rotor core has the permanent magnet Formed by one end of the embedded hole and the outer peripheral flux barrier located near the outer periphery of the rotor core and the other end of the embedded hole. And an inner flux barrier located on the inner side of the flux barrier, and the rotor is disposed at a diagonal position of the permanent magnet in the embedded hole. A continuous filling hole is formed along the axial direction of the inner wall, and the inner flux barrier is an oil passage through which cooling oil flows, and the outer peripheral flux barrier and the inner flux barrier. Is provided with a support portion that abuts a part of the end face of the permanent magnet and supports the permanent magnet, and the support portion is formed between the filling hole and the corner portion of the permanent magnet having a prismatic shape. Is provided on the opposite side.

  According to the first invention, since the permanent magnet is bonded to the rotor core only at the portions corresponding to the two diagonal positions, the filling amount of the adhesive or the like can be greatly reduced, and the filling operation can be performed quickly and easily. In addition, since the permanent magnet is fitted into the embedded hole, even if it is fixed by adhesion at only two locations, it can sufficiently resist the centrifugal force when the rotor rotates, and the permanent magnet is securely held in the embedded hole. It is possible to leave.

According to the second invention, since the flux barrier is not filled with the adhesive, the flux barrier can be reliably secured as an oil passage for circulating the cooling oil, and the permanent magnet and the rotor core can be cooled well.
According to the third aspect of the invention, since the support portion is provided on the flux barrier, the permanent magnet fitted in the embedded hole can be more reliably fixed, and the permanent magnet can be prevented from falling off in the embedded hole.
According to the fourth invention, since the support portion is provided on the side opposite to the adhesive filling hole across the corner portion of the permanent magnet, the filling hole and the support portion can be sufficiently large and fixed at positions where they do not interfere with each other. Strength and durability can be improved.
According to the fifth aspect, the effects of the first to fourth aspects can be obtained similarly.

A sectional view showing the whole electric motor concerning one embodiment of the present invention. The figure which shows the rotor core of the said electric motor. The enlarged view which expands and shows the principal part of the said rotor core.

[Overall configuration of electric motor]
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing the entire electric motor 1 of the present embodiment. FIG. 2 is a view showing the rotor core 41 of the electric motor 1.

  In FIG. 1, an electric motor 1 includes an annular stator 3 mounted inside a housing 2, and a rotor 4 that is disposed in the stator 3 and is rotatably supported in the housing 2. Such an electric motor 1 is configured as an embedded permanent magnet type synchronous motor in which a permanent magnet 43 is embedded in a rotor core 41 of a rotor 4.

[Stator]
Although not clearly shown in the figure, the stator 3 includes a stator core 31 formed by laminating a large number of electromagnetic steel plates along the axial direction. The stator core 31 includes an outer circumferential yoke 32 that is continuous in the circumferential direction, and a plurality of teeth 33 that project from the yoke 32 toward the central rotor 4. The plurality of teeth 33 are provided at equal intervals along the circumferential direction of the yoke 32. An electromagnetic coil 34 is wound around such a tooth 33.

[Rotor]
The rotor 4 includes an annular rotor core 41 configured by laminating a large number of electromagnetic steel plates along the axial direction in the same manner as the stator core 31, and a rotor shaft 42 inserted through an insertion hole 41A provided in the center of the rotor core 41. And a total of 16 prismatic permanent magnets 43 fitted into the embedded holes 41B (see FIG. 2) of the rotor core 41.

  In FIG. 2, the embedded hole 41 </ b> B of the rotor core 41 is provided in a V shape so as to be symmetric when viewed from the axial center side. A pair of such embedded holes 41B is taken as one set, and one magnetic pole is formed by a pair of permanent magnets 43 embedded in the set of embedded holes 41B. That is, the number of poles of the rotor 4 of this embodiment is eight. The polarities of adjacent magnetic poles are different from each other. The magnetic poles are formed at equal intervals along the circumferential direction of the rotor core 41.

  In the rotor core 41, one end in the longitudinal direction of the embedded hole 41B whose opening shape is a long hole is a flux barrier 41C made of a gap. Of the pair of end surfaces 43B, 43B on the short side of the permanent magnet 43 having a rectangular cross section, one end surface 43B (see FIG. 3) is positioned on the flux barrier 41C. Similarly, the other end in the longitudinal direction of the embedded hole 41B is a similar flux barrier 41D on which the other end face 43B of the permanent magnet 43 is located. That is, a pair of side surfaces 43A (see FIG. 3) on the long side of the permanent magnet 43 are in contact with the inner surface of the embedded hole 41B except for a part of an end surface 43B that comes into contact with support portions 71 and 72 described later. doing.

  Of the flux barriers 41 </ b> C and 41 </ b> D, the flux barrier 41 </ b> C located on the outer peripheral side of the rotor core 41 is provided in order to reduce the leakage magnetic flux from the permanent magnet 43. The flux barrier 41D located on the inner side far from the outer peripheral surface of the rotor core 41 is provided to reduce leakage magnetic flux from the permanent magnet 43 and to constitute a part of a cooling structure described later. A side bridge 44 is provided between the flux barrier 41C and the outer peripheral surface of the rotor core 41, and a center bridge 45 is provided between the flux barriers 41D adjacent to each other on the center side of the magnetic pole. The side bridge 44 will be described later.

  On both sides of the rotor core 41 in the axial direction, annular end plates 46 and 47 are attached. On the side of the output portion 42A (left side in FIG. 1) of the rotor shaft 42, the end plate 46 attached to the rotor core 41 communicates the portion corresponding to the flux barrier 41D of the rotor core 41 and the rotor shaft 42 side. A path 46A is provided along the radial direction. A discharge hole 46B opened in the housing 2 is provided at the end of the oil passage 46A. The other end plate 47 is provided with a discharge opening 47A at a position corresponding to the flux barrier 41D, and the flux barrier 41D communicates with the inside of the housing 2. In the present embodiment, the horizontal electric motor 1 in which the axial direction of the rotor shaft 42 is substantially horizontal is described. However, in the present invention, the vertical electric motor in which the axial direction of the rotor shaft is substantially vertical is described. An electric motor may be used. And when set vertically, the discharge hole 46B may be omitted.

  In the center of the rotor shaft 42, there is provided an oil passage 42B that opens on the side opposite to the output portion 42A and extends toward the output portion 42A along the axial direction. The end portion on the output portion 42A side of the oil passage 42B communicates with the oil passage 42C penetrating in the radial direction. The oil passage 42 </ b> C communicates with the oil passage 46 </ b> A of the end plate 46.

  As the permanent magnet 43, a rare earth permanent magnet such as neodymium or dysprosium is preferably used. Such a permanent magnet 43 is fixed by an adhesive in a state of being fitted in the embedded hole 41B of the rotor core 41. The fixing structure of the permanent magnet 43 will be described later.

(Cooling structure)
In the electric motor 1, the stator core 31, the electromagnetic coil 34, the rotor core 41, and the permanent magnet 43 are in a high temperature state due to heat generation caused by hysteresis loss and eddy current loss. For this reason, in the present embodiment, a structure in which the cooling oil circulates between the inside of the housing 2 and the external cooling oil tank 51 to cool the electric motor 1 is adopted.

  In this structure, the supply flow path 52 from the cooling oil tank 51 is connected to the opening side of the oil path 42 </ b> B provided in the rotor shaft 42 of the electric motor 1. On the other hand, a drain passage 53 to the cooling oil tank 51 is connected to a drain opening 2 </ b> A provided in the bottom portion of the housing 2 constituting the electric motor 1. The supply passage 52 is provided with a hydraulic pump 54, and the drain passage 53 is provided with an oil cooler 55.

  The cooling oil sucked up by the hydraulic pump 54 from the cooling oil tank 51 enters the oil passage 42B of the rotor shaft 42, flows in the oil passage 42B from one end side to the other end side along the axial direction, and the other end. It flows into the oil passage 46A of the end plate 46 through the radial oil passage 42C provided on the side.

  A part of the cooling oil that has entered the oil passage 46A is injected into the housing 2 from the discharge hole 46B to cool the rotor core 41 and the electromagnetic coil 34. Further, the other cooling oil that has entered the oil passage 46A enters the flux barrier 41D of the rotor core 41 and cools the rotor core 41 and the permanent magnet 43 by flowing in the flux barrier 41D along the axial direction. The cooling oil that has finished flowing through the flux barrier 41D is injected into the housing 2 from the discharge opening 47A of the end plate 47, and also cools the rotor core 41 and the electromagnetic coil 34.

  The cooling oil sprayed from the discharge hole 46B and the discharge opening 47A cools the rotor core 41 and the electromagnetic coil 34, and cools the bearings 21 and 22 that support the rotation of the rotor shaft 42. The cooling oil that has cooled them is dropped into the housing 2 and collected in the oil reservoir 23 at the bottom. The collected cooling oil flows from the oil reservoir 23 through the drain opening 2 </ b> A through the drain passage 53, is cooled by the oil cooler 55, and then returns to the cooling oil tank 51.

[Side Bridge]
FIG. 3 is an enlarged view showing a main part of the rotor core 41 in an enlarged manner. In FIG. 3, two adjacent poles are shown.
As shown in FIG. 3, the outer peripheral surface of the rotor core 41 is provided with a first recess 61 and a second recess 62 that are recessed inward in the vicinity of the flux barrier 41 </ b> C located near the outer periphery. In each magnetic pole, the first recesses 61 are provided at positions on the outer side in the circumferential direction with respect to the center of the magnetic pole, and the second recesses 62 are provided at positions on the inner side in the circumferential direction with respect to the center of the magnetic pole. And the space | interval of the circumferential direction of the 1st recessed part 61 and the 2nd recessed part 62 is a magnitude | size of the grade which straddles the flux barrier 41C in the circumferential direction. That is, when the line connecting the first recess 61 and the axis center of the rotor core 41 is L1, and the line connecting the second recess 62 and the axis center of the rotor core 41 is L2, the flux barrier 41C is between the lines L1 and L2. Is provided. As a result, the side bridge 44 that connects the first recess 61 and the second recess 62 is formed by the thin portion between the flux barrier 41 </ b> C and the outer peripheral surface of the rotor core 41.

  The side bridge 44 has a substantially uniform thickness (a radial thickness) in the circumferential direction of the rotor core 41 in relation to the opening shape of the flux barrier 41 </ b> C, and on the outer side in the radial direction of the rotor core 41. It is formed in an arch shape curved so as to protrude. That is, the first recess 61 and the second recess 62 are provided on the base end side of the arched side bridge 44. The curvature radius of the side bridge 44 is smaller than the radius of the outer periphery of the rotor core 41.

  In the side bridge 44 having such a shape, stress concentration occurs due to the centrifugal force accompanying the rotation of the rotor 4, but the places where the stress occurs are near both ends in the circumferential direction of the side bridge 44 and the center in the circumferential direction. Specifically, stress is generated by being dispersed at three locations, that is, the bottom portions of the first recess portion 61 and the second recess portion 62 and the inner surface side portion of the side bridge 44 (flux barrier 41C). Therefore, stress concentration does not occur at one point, the stress generated at each location can be reduced, and durability is improved. Of the first recess 61 and the second recess 62, in the present embodiment, the second recess 62 can function as a portion that reduces torque pulsation, iron loss, magnetic flux harmonics, or cogging torque, The characteristics of the electric motor 1 can be improved.

[Permanent magnet fixing structure]
Below, based on FIG. 3, the fixed structure of the permanent magnet 43 is demonstrated.
As shown in FIG. 3, support portions 71 and 72 projecting toward two diagonal positions of the permanent magnet 43 are provided at portions where the flux barriers 41 </ b> C and 41 </ b> D of the steel plate 7 are formed. The support portion 71 on the flux barrier 41 </ b> C side is in contact with the edge farther from the outer peripheral surface of the rotor core 41 in one end face 43 </ b> B of the permanent magnet 43. The support portion 72 on the flux barrier 41D side is provided at the base end portion on the outer side of the center bridge 45, and the other end surface 43B of the permanent magnet 43 is on the edge closer to the outer peripheral surface of the rotor core 41. It is in contact. Thus, the permanent magnet 43 is supported by the rotor core 41 at two diagonal positions on the opposite short side edge.

  Here, the contact width at which the support portions 71 and 72 are in contact with the end surface 43B of the permanent magnet 43 is approximately 1/5 (5 minutes) with respect to the entire width on the short side of the permanent magnet 43 provided with the end surface 43B. It is desirable to be shorter than 1). By being shorter than 1/5, the leakage magnetic flux from the end face 43B can be reduced. Further, the contact portion of the support portions 71 and 72 on the end surface 43 </ b> B may be separated from the end portion in the width direction of the end surface 43 </ b> B that is a corner portion of the permanent magnet 43.

  And in the part which forms the embedding hole 41B of the steel plate 7, the extension part 73 is provided in the position on the opposite side to the support parts 71 and 72 across the corner | angular part of the permanent magnet 43. As shown in FIG. The extended portion 73 is provided by extending a part of the embedded hole 41 </ b> B in order to form a slight gap with the side surface 43 </ b> A of the permanent magnet 43. The extension part 73 is also provided in all the steel plates 7 to be laminated. The laminated steel plates 7 all have the same shape, and by aligning each, an embedded hole 41B communicating with the lamination direction (same as the axial direction of the rotor core 41) is formed, and the permanent magnet 43 is formed in the embedded hole 41B. Can be incorporated.

  In addition, the filling holes 48 penetrating the rotor core 41 along the axial direction are formed in two locations at different diagonal positions of the permanent magnet 43 in the embedded hole 41B by all the extended portions 73 communicating in the stacking direction. Is done. That is, such a filling hole 48 is formed between the permanent magnet 43 and the extended portion 73 in a state where the permanent magnet 43 is incorporated in the embedded hole 41B. By filling the filling hole 48 continuous in the axial direction with the adhesive, the two opposing positions of the opposing long side edges of the permanent magnet 43 are fixed to the rotor core 41. A resin material such as a molding material may be used as the adhesive.

  Therefore, in this embodiment, it is not necessary to rotate and fix the adhesive on the entire side surface 43A of the permanent magnet 43, and the labor for filling the adhesive can be greatly reduced, and the assembling work can be facilitated. Moreover, the permanent magnet 43 is fitted in the embedded hole 41B, and the side surfaces 43A on both sides of the permanent magnet 43 are in contact with the inner surface of the embedded hole 41B. Therefore, the permanent magnet 43 can be reliably held in the embedded hole 41B with at least an adhesive filling amount.

[Modification]
It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
For example, in the above-described embodiment, the filling hole 48 is formed along the axial direction of the rotor core 41. However, a communication portion that communicates the filling hole 48 with the flux barriers 41C and 41D may be further provided. In such a configuration, the air in the filling hole 48 can be extracted through the communication portion, and the filling hole 48 can be easily filled with the adhesive.

  In addition, even when such a communication portion is not provided, in order to fill the adhesive more smoothly, for example, an adhesive filling needle can be inserted into the cross section of the filling hole 48 formed by the expansion portion 73. It may be provided as large as possible. Then, after inserting such a needle to the back side of the filling hole 48, the adhesive is filled through the needle while returning from the back side to the front side.

Further, it is possible to fill the adhesive in a pre-process in which the end plates 46 and 47 are provided on the rotor core 41, that is, in a stage where the end of the filling hole 48 is open.
In addition, even in the process after the end plates 46 and 47 are provided in the rotor core 41, for example, by providing a communication hole in the end plate 46 in advance for communicating the filling hole 48 and the outside. It is also possible to configure such that the air vent is removed when the adhesive is filled through such a communication hole.

  In the embodiment, the first and second recesses 61 and 62 are provided on the outer peripheral surface of the rotor core 41. However, only the second recess 62 that functions to improve the characteristics of the generator 1 is provided. Even when the concave portion 61 is omitted or when both the first and second concave portions 61 and 62 are absent, the present invention includes the present invention.

  The present invention is used in vehicles such as an electric vehicle, a hybrid vehicle, an electric construction machine, and a hybrid construction machine, and can be preferably used as an electric motor for running these construction machines.

  DESCRIPTION OF SYMBOLS 1 ... Electric motor, 2 ... Housing, 3 ... Stator, 4 ... Rotor, 41 ... Rotor core, 41B ... Embedded hole, 41C, 41D ... Flux barrier, 43 ... Permanent magnet, 48 ... Filling hole, 71, 72 ... Support part.

Claims (5)

An electric motor comprising an annular stator mounted in a housing and a rotor disposed in the stator and rotatably supported by the housing, and a plurality of permanent magnets embedded in a rotor core of the rotor. And
The rotor core is provided with a buried hole for installing the permanent magnet,
Supporting portions that are continuous along the axial direction of the rotor core and are in contact with the short sides of the permanent magnets are provided at opposing positions on the short sides of the permanent magnets in the embedded holes,
The electric motor according to claim 1, wherein a filling hole that is continuous along the axial direction of the rotor core and is filled with an adhesive is formed at a diagonal position of the permanent magnet in the embedded hole. The electric motor according to claim 1,
The rotor core is provided with a flux barrier by the end of the embedded hole,
The electric motor characterized in that the flux barrier is an oil passage through which cooling oil flows. The electric motor according to claim 1 or 2, wherein the rotor core is provided with a flux barrier by an end portion of the embedded hole,
The electric motor, wherein the flux barrier is provided with the support portion for supporting the permanent magnet. The electric motor according to claim 3,
The electric motor according to claim 1, wherein the support portion is provided on a side opposite to the filling hole across a corner portion of the permanent magnet having a prism shape. An annular stator mounted in the housing, and a rotor disposed in the stator and rotatably supported by the housing, and a plurality of rectangular permanent magnets embedded in the rotor core of the rotor An electric motor,
One magnetic pole is formed by a pair of the permanent magnets arranged in a V shape when viewed from the axial center of the rotor,
In the rotor core,
Embedded holes for installing the permanent magnets;
An outer peripheral flux barrier formed by one end of the embedded hole and located near the outer periphery of the rotor core;
An inner flux barrier formed by the other end of the embedded hole and located on the inner side of the flux barrier; and
Supporting portions that are continuous along the axial direction of the rotor core and are in contact with the short sides of the permanent magnets are provided at opposing positions on the short sides of the permanent magnets in the embedded holes,
Filling holes that are continuous along the axial direction of the rotor core and are filled with an adhesive are formed at diagonal positions of the permanent magnets in the embedded holes,
The inner flux barrier is an oil passage through which cooling oil flows,
The outer periphery side flux barrier and the inner side flux barrier are provided with the support portion that contacts the part of the end surface of the permanent magnet and supports the permanent magnet,
The electric motor according to claim 1, wherein the support portion is provided on a side opposite to the filling hole across a corner portion of the permanent magnet having a prism shape.

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