JP3633232B2 - Electric motor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric motor.
[0002]
[Prior art]
Conventionally, an electric motor has a rotor and a stator disposed around the rotor, and the stator includes a stator core and a stator coil wound around the stator core. When a current is supplied to the stator coil and a rotating magnetic field is formed, the rotor rotates.
[0003]
Further, in a synchronous motor in which magnetic poles are formed by disposing permanent magnets on the rotor, permanent magnets are disposed at a plurality of locations on a core formed by stacking electromagnetic steel plates.
FIG. 2 is a cross-sectional view of a main part of a conventional synchronous motor.
In the figure, reference numeral 14 denotes a motor case, and a synchronous motor 15 is accommodated in the motor case 14. The motor case 14 includes a cylindrical portion 14a and a lid (lid) portion 14b that forms a sealed motor housing chamber 18 by closing one end of the cylindrical portion 14a. A plurality of fins 24 are formed on the outer peripheral surface of the cylindrical portion 14a.
[0004]
A hole is formed in the center of the bottom of the cylindrical portion 14a and the center of the lid portion 14b, and a motor shaft 27 is disposed through the hole. The motor shaft 27 is supported by bearings 29 and 30. It is supported rotatably. Further, a recess 14c is formed adjacent to the hole of the lid portion 14b, and the sensor chamber 34 is formed by closing the recess 14c with the lid member 33.
[0005]
A resolver 35 is disposed in the sensor chamber 34, and the resolver 35 detects the position of the magnetic pole of the electric motor 15 based on the rotation of the motor shaft 27.
The electric motor 15 is mounted at substantially the center in the axial direction of the motor shaft 27, and is made to face the rotor 37 on the rotor 37 rotated together with the motor shaft 27 and the inner peripheral surface of the cylindrical portion of the cylindrical portion 14a. The stator 38 includes a stator core 38a and a three-phase (U-phase, V-phase, and W-phase) coil 39 wound around the stator core 38a.
[0006]
Therefore, the rotor 37 can be rotated by supplying a three-phase alternating current generated in an inverter (not shown) to each coil 39.
The rotor 37 includes a core 17 formed by laminating a plurality of electromagnetic steel plates, and permanent magnets 55 disposed at a plurality of locations of the core 17. The permanent magnets 55 are arranged at equal pitches at a plurality of locations. The permanent magnet 55 is fixed in a state of being pressed by end plates 56 and 57 disposed at both ends, and forms a magnetic pole of the electric motor 15. For this purpose, a spline 27a is formed on the outer peripheral surface of the motor shaft 27, a spline 37a is formed on the inner peripheral surface of the rotor 37, and splines 56a and 57a are formed on the inner peripheral surfaces of the end plates 56 and 57, respectively. The rotor 37 and the end plates 56 and 57 can be spline-engaged.
[0007]
A locking projection 27 b is formed on the outer peripheral surface of the motor shaft 27 so as to be adjacent to the bearing 30. Therefore, the end plate 57 is pressed against the locking projection 27b, and the end plate 57, the rotor 37 and the end plate 56 are sequentially set on the motor shaft 27, and the locking nut 16 is screwed into a predetermined portion of the motor shaft 27. By combining, the rotor 37 can be positioned and fixed with respect to the motor shaft 27.
[0008]
The end plates 56 and 57 have an annular shape corresponding to the rotor 37, and have a radial dimension such that the outer peripheral edge is slightly inward from the outer peripheral edge of the rotor 37. Therefore, the end surfaces of the rotor 37 and the permanent magnet 55 can be pressed and covered by the end plates 56 and 57, so that the rotor 37 can be prevented from moving in the axial direction, and the permanent magnet 55 is damaged. It is possible to prevent the magnet pieces from being scattered around.
[0009]
On the other hand, in an induction motor using a squirrel-cage rotor as a rotor, both ends of copper bars disposed at a plurality of locations in the circumferential direction of the rotor are connected by a short-circuit ring.
FIG. 3 is a schematic view of a rotor of a conventional induction motor.
In the figure, 101 is a rotor, 102 is a motor shaft, 103 is a copper rod disposed at a plurality of positions in the circumferential direction at an equal pitch on the outer periphery of the rotor 101, and 104 is connected to both ends of each rod 103. This is an aluminum short-circuited ring.
[0010]
[Problems to be solved by the invention]
However, in the conventional electric motor, in the case of the synchronous motor 15 (FIG. 2), the end plates 56, 57 cover the end surfaces of the rotor 37 and the permanent magnet 55 with the end plates 56, 57. Has a radial dimension that is slightly inward from the outer peripheral edge of the rotor 37, the outer peripheral edges of the end plates 56 and 57 are close to the coil end of the coil 39.
[0011]
The end plates 56 and 57 are usually made of a nonmagnetic metal. Therefore, when an alternating current is supplied to the coil 39, an eddy current is generated in the end plates 56 and 57 due to a high frequency component included in the alternating current or an induced electromotive force generated along with the alternating current, Reduce efficiency.
[0012]
In the case of an induction motor, short-circuit rings 104 are disposed at both ends of the rod 103 in the rotor 101, and the short-circuit rings 104 are usually formed of a nonmagnetic metal. As a result, an eddy current is generated in the short-circuit ring 104 and the efficiency of the motor is lowered.
An object of the present invention is to solve the problems of the conventional electric motor and to provide an electric motor that can suppress the generation of eddy current and increase the efficiency.
[0013]
[Means for Solving the Problems]
Therefore, in the electric motor of the present invention, a rotor in which permanent magnets are arranged at a plurality of locations in the circumferential direction of the core, a stator arranged at a predetermined interval from the rotor, and a winding around the stator Coil.
And it has the end plate which fixes in the state which pressed down the both ends of the said permanent magnet, and covers the end surface of a rotor and a permanent magnet.
[0014]
Further, the end plate includes a step portion formed at a portion opposite to the end surface in the axial direction, and an air gap between an outer peripheral edge of the portion not covering the end surface and an inner peripheral edge of the coil is increased, The outer peripheral edge of the part covering the end face is arranged closer to the coil end than the outer peripheral edge of the part not covering the end face.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view of an essential part of a synchronous motor according to a first embodiment of the present invention.
In the figure, reference numeral 14 denotes a motor case, and a synchronous motor 15 is accommodated in the motor case. The motor case 14 includes a cylindrical portion 14a and a lid portion 14b that closes one end of the cylindrical portion 14a to form a sealed motor accommodating chamber 18. A plurality of fins 24 are formed on the outer peripheral surface of the cylindrical portion 14a.
[0018]
A hole is formed in the center of the bottom of the cylindrical portion 14a and the center of the lid portion 14b, and a motor shaft 27 is disposed through the hole. The motor shaft 27 is supported by bearings 29 and 30. It is supported rotatably. Further, a recess 14c is formed adjacent to the hole of the lid portion 14b, and the sensor chamber 34 is formed by closing the recess 14c with the lid member 33.
[0019]
A resolver 35 is disposed in the sensor chamber 34, and the resolver 35 detects the position of the magnetic pole of the electric motor 15 based on the rotation of the motor shaft 27.
The electric motor 15 is mounted at substantially the center in the axial direction of the motor shaft 27, and is made to face the rotor 37 on the rotor 37 rotated together with the motor shaft 27 and the inner peripheral surface of the cylindrical portion of the cylindrical portion 14a. And a stator 38 disposed at a predetermined distance from the rotor 37. The stator 38 has a stator core 38a and three phases (U phase, V phase) wound around the stator core 38a. And a W-phase) coil 139.
[0020]
Therefore, the rotor 37 can be rotated by supplying each coil 139 with a three-phase alternating current generated in an inverter (not shown).
The rotor 37 includes a core 17 formed by laminating a plurality of electromagnetic steel plates, and permanent magnets 55 disposed at a plurality of locations of the core 17. The permanent magnets 55 are arranged at equal pitches at a plurality of locations. The permanent magnet 55 is fixed while being pressed by end plates 156 and 157 as end members disposed at both ends, and forms a magnetic pole of the motor 15. For this purpose, a spline 27a is formed on the outer peripheral surface of the motor shaft 27, a spline 37a is formed on the inner peripheral surface of the rotor 37, and splines 56a and 57a are formed on the inner peripheral surfaces of the end plates 156 and 157. The rotor 37 and the end plates 156 and 157 can be spline-engaged.
[0021]
A locking projection 27 b is formed on the outer peripheral surface of the motor shaft 27 so as to be adjacent to the bearing 30. Therefore, the end plate 157 is pressed against the locking projection 27b, the end plate 157, the rotor 37 and the end plate 156 are sequentially set on the motor shaft 27, and the locking nut 16 is screwed into a predetermined portion of the motor shaft 27. Thus, the rotor 37 can be positioned and fixed with respect to the motor shaft 27.
[0022]
The end plates 156 and 157 have an annular shape corresponding to the rotor 37, and have a radial dimension such that the outer peripheral edge is slightly inward from the outer peripheral edge of the rotor 37. Accordingly, the end surfaces of the rotor 37 and the permanent magnet 55 can be pressed and covered by the end plates 156 and 157, so that the rotor 37 can be prevented from moving in the axial direction, and the permanent magnet 55 can be damaged. It is possible to prevent the magnet pieces from being scattered around.
[0023]
By the way, in order to cover the end surfaces of the rotor 37 and the permanent magnet 55 by the end plates 156, 157, the end plates 156, 157 have a radial dimension such that the outer peripheral edge is slightly inward from the outer peripheral edge of the rotor 37. Therefore, the outer peripheral edges of the end plates 156 and 157 are close to the coil end of the coil 139. The end plates 156 and 157 are usually formed of a nonmagnetic metal.
[0024]
Therefore, when an alternating current is supplied to the coil 139, an eddy current is generated in the end plates 156 and 157 due to a high frequency component included in the alternating current or an induced electromotive force generated along with the alternating current. Reduce efficiency.
Therefore, in order to suppress the generation of eddy currents in the end plates 156, 157, annular step portions 158, 159 as eddy current generation suppression portions are formed in the end plates 156, 157. Moreover, the coil ends 161 and 162 as the eddy current generation suppressing portion are bent outward in the radial direction.
[0025]
Accordingly, since the air gap between the outer peripheral edge of the end plates 156 and 157 and the inner peripheral edge of the coil 139 is increased, the number of magnetic fluxes linking the end plates 156 and 157 can be reduced accordingly. As a result, the generation of eddy currents in the end plates 156 and 157 can be suppressed, so that the efficiency of the electric motor 15 can be increased.
[0026]
Further, the rotor 37 can be reduced in weight by the amount that the step portions 158 and 159 are formed.
Next, a second embodiment of the present invention will be described.
FIG. 4 is a cross-sectional view of a main part of the synchronous motor according to the second embodiment of the present invention. In addition, about the thing which has the same structure as 1st Embodiment, the description is abbreviate | omitted by providing the same code | symbol.
[0027]
In this case, in order to suppress the generation of eddy currents in the end plates 256 and 257 as end members, annular tapered surfaces 258 and 259 as eddy current generation suppressing portions are formed on the end plates 256 and 257, respectively. The Moreover, the coil ends 161 and 162 as the eddy current generation suppressing portion are bent outward in the radial direction.
Therefore, since the air gap between the outer peripheral edge of the end plates 256 and 257 and the inner peripheral edge of the coil 139 is increased, the number of magnetic fluxes that link the end plates 256 and 257 can be reduced accordingly. As a result, the generation of eddy currents in the end plates 256 and 257 can be suppressed, so that the efficiency of the electric motor 15 can be increased.
[0028]
Further, the rotor 37 can be reduced in weight by the amount that the tapered surfaces 258 and 259 are formed.
In the first and second embodiments, the end plates 156, 157, 256, and 257 all have an annular shape, but only a portion that covers the end surface of the permanent magnet 55 protrudes radially outward. Other parts can be cut into a radial shape.
[0029]
Next, a third embodiment of the present invention will be described.
FIG. 5 is a schematic view of the rotor of the induction motor according to the third embodiment of the present invention, and FIG. 6 is a side view of the rotor of the induction motor according to the third embodiment of the present invention.
In the figure, 201 is a rotor, 202 is a motor shaft, 203 is a copper bar disposed at a plurality of positions in the circumferential direction at an equal pitch, and 204 is connected to both ends of each bar 203. This is a short-circuited ring made of aluminum as an end member.
[0030]
In this case, in order to suppress the generation of eddy current in the short-circuit ring 204, an annular step portion 205 as an eddy current generation suppression portion is formed in the short-circuit ring 204.
Therefore, since the air gap between the outer peripheral edge of the short-circuit ring 204 and the inner peripheral edge of the coil (not shown) is increased, the number of magnetic fluxes interlinking the short-circuit ring 204 can be reduced accordingly. As a result, the generation of eddy current in the short-circuit ring 204 can be suppressed, so that the efficiency of the electric motor can be increased.
[0031]
Further, the rotor 201 can be reduced in weight by the amount that the step portion 205 is formed.
Next, a fourth embodiment of the present invention will be described.
FIG. 7 is a schematic view of the rotor of the induction motor according to the fourth embodiment of the present invention.
[0032]
In the figure, 301 is a rotor, 302 is a motor shaft, 303 is a copper rod, and 304 is a short circuit ring as an end member.
In this case, in order to suppress the generation of eddy currents in the short-circuit ring 304, an annular tapered surface 305 as an eddy current generation suppression portion is formed in the short-circuit ring 304.
Therefore, since the air gap between the outer peripheral edge of the short-circuit ring 304 and the inner peripheral edge of the coil (not shown) is increased, the number of magnetic fluxes interlinking the short-circuit ring 304 can be reduced accordingly. As a result, the generation of eddy currents in the short-circuit ring 304 can be suppressed, and the efficiency of the electric motor can be increased.
[0033]
Further, the rotor 301 can be reduced in weight by the amount that the tapered surface 305 is formed.
Next, a fifth embodiment of the present invention will be described.
FIG. 8 is a schematic diagram of a rotor of an induction motor according to a fifth embodiment of the present invention.
[0034]
In the figure, 401 is a rotor, 402 is a motor shaft, 403 is a copper rod, and 404 is a short-circuit ring as an end member.
In this case, in order to suppress the generation of eddy currents in the short-circuit ring 404 and the rod 403, annular tapered surfaces 405 as eddy current generation suppression portions are formed at both ends of the short-circuit ring 404 and the rod 403.
[0035]
Therefore, since the air gap between the outer peripheral edge of the short-circuit ring 404 and the inner peripheral edge of the coil (not shown) is increased, the number of magnetic fluxes interlinking the short-circuit ring 404 can be reduced accordingly. As a result, the generation of eddy current in the short-circuit ring 404 can be suppressed, so that the efficiency of the electric motor can be increased.
Further, the rotor 401 can be reduced in weight by the amount that the tapered surface 405 is formed.
[0036]
In addition, this invention is not limited to the said embodiment, It can change variously based on the meaning of this invention, and does not exclude them from the scope of the present invention.
[0037]
【The invention's effect】
As described above in detail, according to the present invention, in the electric motor, the rotor in which the permanent magnets are disposed at a plurality of locations in the circumferential direction of the core, and the rotor is disposed at a predetermined interval. A stator and a coil wound around the stator are provided.
And it has the end plate which fixes in the state which pressed down the both ends of the said permanent magnet, and covers the end surface of a rotor and a permanent magnet.
Further, the end plate includes a step portion formed in a portion opposite to the end surface in the axial direction, and an air gap between an outer peripheral edge of the portion not covering the end surface and an inner peripheral edge of the coil is increased, The outer peripheral edge of the part covering the end face is arranged closer to the coil end than the outer peripheral edge of the part not covering the end face.
[0038]
In this case, since the air gap between the outer peripheral edge of the end plate that does not cover the end faces of the rotor and the permanent magnet and the inner peripheral edge of the coil is increased in the end plate, the number of magnetic fluxes linking the end plate is reduced accordingly. can do. As a result, the generation of eddy current in the end plate can be suppressed, and the efficiency of the electric motor can be increased.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a main part of a synchronous motor according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view of a main part of a conventional synchronous motor.
FIG. 3 is a schematic view of a rotor of a conventional induction motor.
FIG. 4 is a cross-sectional view of a main part of a synchronous motor according to a second embodiment of the present invention.
FIG. 5 is a schematic diagram of a rotor of an induction motor according to a third embodiment of the present invention.
FIG. 6 is a side view of a rotor of an induction motor according to a third embodiment of the present invention.
FIG. 7 is a schematic view of a rotor of an induction motor according to a fourth embodiment of the present invention.
FIG. 8 is a schematic diagram of a rotor of an induction motor according to a fifth embodiment of the present invention.
[Explanation of symbols]
15 Motor 17 Core 37, 201, 301, 401 Rotor 38 Stator 55 Permanent magnet 139 Coil 156, 157, 256, 257 End plate 158, 159, 205 Step part 161, 162 Coil end 203, 303, 403 Rod 204, 304, 404 Shorted ring 258, 259, 305, 405 Tapered surface

Claims (1)

In an electric motor comprising a rotor in which permanent magnets are disposed at a plurality of locations in the circumferential direction of the core, a stator disposed at a predetermined interval from the rotor, and a coil wound around the stator. The end plate is fixed in a state where both ends of the permanent magnet are pressed, and has an end plate that covers the end surfaces of the rotor and the permanent magnet, and the end plate is formed in a portion opposite to the end surface in the axial direction. the provided, the air gap between the inner periphery of the outer peripheral edge and a coil portion does not cover the front SL end surface is large, the coil end of the outer periphery of the portion outer peripheral edge of the portion covering the end surface does not cover the end face An electric motor characterized in that it is disposed in close proximity to the motor .

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