JP2008022592A - Electric motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric motor which can suppress deterioration of the magnetic characteristics. <P>SOLUTION: The electric motor 1 comprises a cylindrical frame 19 and a stator core 5, which is press-fit into the frame 19. Grooves 14 for coil winding are formed at both ends of the stator core 5 with respect to the axial direction Z1, and the external wall of the groove 14 is constituted of ends 12 of a yoke 7, which constitutes a part of the stator core 5. A ring-shaped recess 16 is formed at the external periphery 15 of the stator core 5, in a range in which the external periphery 18 of the external wall 12 of the groove 14 is excluded. A non-contact region A1, which will not contact the internal periphery 20a of the frame 19, is formed at the external periphery 15 of the stator core 5, corresponding to the ring-shaped recess 16, and a pair of press-insertion regions B1, B2 are formed on both sides with the non-contact region A1, interposed therebetween in the axial direction Z1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electric motor.

An electric motor usually includes a cylindrical stator core and a coil wound around the stator core, and the stator core is held by a cylindrical frame. For example, in Patent Document 1 below, the stator core is fixed to the frame by shrink fitting.
JP 2004-40948 A

However, when the stator core is fixed to the frame by shrink fitting or press fitting, stress due to shrink fitting or press fitting is applied to a part of the stator core. As a result, the magnetic flow in the stator core is disturbed, and the magnetic properties of the stator core are degraded. For this reason, an iron loss increases and a loss torque becomes large.
The present invention has been made based on such a background, and an object thereof is to provide an electric motor capable of suppressing a decrease in magnetic characteristics.

In order to achieve the above object, the present invention comprises a cylindrical frame (19) and an annular stator core (5) around which a coil (6) is wound and press-fitted into the frame, and the outer periphery (15) of the stator core. Further, the electric motor (1) is characterized in that non-contact areas (A1 to A4) that are not in contact with each other are formed between the inner periphery (20a) of the frame.
According to the present invention, the stress applied to the stator core can be reduced in the portion corresponding to the non-contact region. Therefore, it is possible to suppress a decrease in the magnetic characteristics of the stator core.

In the present invention, a recess (16, 16a, 27, 29) is formed on at least one of the outer periphery of the stator core and the inner periphery of the frame, and the non-contact region is formed corresponding to the recess. There is. In this case, a non-contact region can be reliably formed on the outer periphery of the stator core by forming the recess.
In the present invention, the stator core includes a pair of end portions (12) in the axial direction (Z1) of the stator core and an intermediate portion (26) between the pair of end portions, and the non-contact region (A1). Is formed on the outer periphery (28) of the intermediate portion, and the press-fitted region (B1, B2) for the frame may be formed on the outer periphery (18) of the pair of end portions. In this case, since the non-contact region is formed in the intermediate part that is likely to affect the magnetic characteristics when subjected to stress, it is possible to effectively suppress the deterioration of the magnetic characteristics of the stator core. Moreover, the stator core can be securely fixed to the frame by forming the press-fitting region on the outer periphery of the pair of end portions.

In the present invention, the stator core includes a pair of end portions in the axial direction of the stator core and an intermediate portion between the pair of end portions, and the non-contact region (A2, A3) is the pair of end portions. It may be formed on the outer periphery of. In this case, since stress applied to the pair of end portions can be reduced, durability of the end portions can be improved.
In the present invention, the pair of end portions of the stator core includes a dust core (P), and the coil winding grooves (14) open to the pair of end portions outward in the axial direction of the stator core. May be provided. In this case, since the powder core has a high degree of freedom in shape, a coil winding groove can be easily formed at the pair of ends.

  In the above description, the alphanumeric characters in parentheses represent reference numerals of corresponding components in the embodiments described later, but the scope of the claims is not limited by these reference numerals.

Embodiments of the present invention will be specifically described below with reference to the drawings.
FIG. 1 is a cross-sectional view schematically showing a schematic configuration of the electric motor 1 according to the first embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view showing a part of a cross section taken along line II-II of the electric motor 1 in FIG.
Referring to FIG. 1, an electric motor 1 according to the present embodiment is a brushless motor, and includes a rotor 3 connected to a rotary shaft 2 so as to be integrally rotatable, and an annular stator 4 surrounding an outer periphery of the rotor 3. .

The rotor 3 has a cylindrical shape, and a plurality of permanent magnets (not shown) are arranged along the circumferential direction X1 of the electric motor 1 on the outer periphery thereof. The outer periphery of the rotor 3 is a magnetic pole in which the N pole and the S pole are alternately switched in the circumferential direction X1.
Referring to FIG. 2, stator 4 includes a stator core 5 and a coil 6 wound around stator core 5. The stator core 5 is constituted by a dust core P, and has an annular yoke 7 and a plurality of teeth 8 that are formed to protrude from the inner periphery 7 a of the yoke 7. The dust core P is a magnetic core obtained by compressing and molding a powder material containing a soft magnetic material and hardening it by sintering or resin. Examples of the soft magnetic material include pure iron, iron silicon alloy, iron aluminum alloy, iron nickel alloy, carbonyl iron, CSC (Coasted Single Crystal), and ferrite.

  The annular yoke 7 is divided in the circumferential direction X1, and is constituted by a plurality of divided bodies 9 having an arc shape. The teeth 8 are formed so as to protrude from the inner periphery of each divided body 9. Therefore, the plurality of teeth 8 are annularly arranged together with the plurality of divided bodies 9. In the present embodiment, each divided body 9 and the teeth 8 corresponding thereto are integrally formed of a single material (powder material including the soft magnetic material).

The teeth 8 are generally T-shaped, and extend from the inner periphery 7a of the yoke 7 to the inside of the electric motor 1 in the radial direction Y1 and extend from both ends of the main body 10 to both sides in the circumferential direction X1. Part 11. The coil 6 is wound along the main body 10.
A slot S is formed between the teeth 8 adjacent to each other in the circumferential direction of the yoke 7 (the same direction as the circumferential direction X1 in FIG. 2). That is, the adjacent teeth 8 are annularly arranged with the slot S interposed in the circumferential direction X1.

  Referring to FIG. 1 again, with respect to the axial direction Z1 of the stator core 5, the yoke 7 and the extending portion 11 are longer than the main body portion 10 of the tooth 8, and both ends 12 of the yoke 7 and both ends of the extending portion 11 are provided. 13 protrudes outward from the end face of the main body 10 in the axial direction Z1. Therefore, at both ends of the stator core 5 in the axial direction Z1, the coil winding is defined by the inner periphery of the end portion 12 of the yoke 7, the outer periphery of the end portion 13 of the extending portion 11, and the end surface of the main body portion 10. The groove 14 is formed corresponding to each tooth 8.

The outer wall of each groove 14 is constituted by the end portion 12 of the yoke 7, and the inner wall of each groove 14 is constituted by the end portion 13 of the extending portion 11. Further, the bottom surface of each groove 14 is constituted by the end surface of the main body 10.
Referring to FIGS. 1 and 2, an annular recess 16 extending in the axial direction Z <b> 1 with a predetermined length is formed on the outer periphery 15 of the stator core 5. The annular recess 16 is constituted by a plurality of arc-shaped recesses 17 formed on the outer periphery of each divided body 9 as shown in FIG. 2, and the groove is formed on the outer periphery 15 of the stator core 5 as shown in FIG. 1. An annular recess 16 is formed in a range excluding the outer periphery 18 of the outer wall 14 (the end 12 of the yoke 7).

With reference to FIG. 1, the rotor 3 and the stator 4 are accommodated in a cylindrical frame 19. The frame 19 includes a tubular portion 20 and a pair of end walls 21 and 22 disposed at the end of the tubular portion 20. In the present embodiment, one of the pair of end walls 21 and 22 (the end wall 21 in the present embodiment) and the cylindrical portion 20 are integrally formed of a single material.
Insertion holes 23 through which the rotary shaft 2 is inserted are respectively formed in the center portions of the pair of end walls 21 and 22. Each insertion hole 23 is formed with a bearing holding portion 25 that holds the bearing 24, and the rotary shaft 2 is rotatably held by the frame 19 via the bearing 24 held by the bearing holding portion 25. .

  The stator core 5 is fixed to the inner periphery 20a of the cylindrical portion 20 by, for example, press fitting. Since the annular recess 16 is formed on the outer periphery 15 of the stator core 5 as described above, the outer periphery 15 of the stator core 5 corresponding to the annular recess 16 is not in contact with the inner periphery 20 a of the tubular portion 20. A non-contact area A1 is formed. Further, on both sides sandwiching the non-contact area A1 in the axial direction Z1, a pair of outer periphery 15 of the stator core 5 (a range including the outer periphery 18 of the outer wall 12 of each groove 14) is in contact with the inner periphery 20a of the cylindrical portion 20. The press-fitting regions B1 and B2 are respectively formed.

Therefore, the stress generated by press-fitting the stator core 5 into the cylindrical portion 20 is applied to the outer wall 12 of the groove 14 and the vicinity thereof, and is applied to the intermediate portion 26 in the axial direction Z1 of the stator core 5 where the non-contact region A1 is formed. In this case, the stress is hardly applied.
As described above, in this embodiment, the non-contact region A1 is formed on the outer periphery 28 of the intermediate portion 26 of the stator core 5 that is likely to affect the magnetic characteristics of the stator core 5, so that the press-fitting applied to the intermediate portion 26 is performed. The stress resulting from fitting can be reduced. Accordingly, it is possible to suppress a decrease in the magnetic characteristics of the stator core 5.

In addition, by forming the pair of press-fit regions B1 and B2 on the outer circumferences at both ends of the stator core 5, the stator core 5 can be reliably fixed to the frame 19 with almost no deterioration in the magnetic characteristics of the stator core 5.
The first embodiment described above can be modified as follows. That is, in the first embodiment, the case where the entire stator core 5 is the dust core P has been described. However, the stator core 5 may include the dust core P and the laminated steel plate Q. In the first embodiment, the case where the annular recess 16 is formed on the outer periphery 15 of the stator core 5 has been described. However, the annular recess 16 may be formed on the inner periphery 20 a of the cylindrical portion 20 of the frame 19. Good.

When the stator core 5 includes the dust core P and the laminated steel plate Q, the intermediate portion 26 of the stator core 5 may be the laminated steel plate Q and both ends of the stator core 5 may be the dust core P as shown in FIG. By disposing the dust cores P having a high degree of freedom at both ends of the stator core 5, the grooves 14 can be easily formed at both ends of the stator core 5.
The laminated steel sheet Q is formed by stacking and fixing a plurality of thin plates formed by punching electromagnetic steel sheets into a predetermined shape in the axial direction Z1. As the electromagnetic steel plate, for example, a silicon steel plate whose surface is insulated can be used.

  When the annular recess 16a is formed on the inner periphery 20a of the cylindrical portion 20 of the frame 19, as shown in FIG. 4, the inner periphery 20a of the cylindrical portion 20 does not face the outer periphery 18 of the outer wall 12 of each groove 14. An annular recess 16a may be formed in the range. In this case, since the non-contact region A1 is formed on the outer periphery 28 of the intermediate portion 26 of the stator core 5 which is a portion that easily affects the magnetic characteristics by the annular recess 16a, the deterioration of the magnetic characteristics of the stator core 5 can be suppressed. it can.

FIG. 5 is a cross-sectional view schematically showing a schematic configuration of the electric motor 1 according to the second embodiment of the present invention. In FIG. 5, the same components as those shown in FIG. 1 described above are denoted by the same reference numerals as those in FIG.
Referring to FIG. 5, the second embodiment is mainly different from the first embodiment in that the intermediate portion 26 of the stator core 5 is constituted by the laminated steel plate Q, and both ends of the stator core 5 are constituted by the dust core P. The outer periphery 28 of the intermediate portion 26 protrudes outward in the radial direction Y1 from the outer periphery 18 of the outer wall 12 of the groove 14. That is, annular recesses 27 including the outer periphery 18 of the outer wall 12 of the groove 14 and the end face of the intermediate portion 26 are formed at both ends of the stator core 5.

In a state where the stator core 5 is press-fitted to the frame 19, a press-fit region B3 is formed on the outer periphery 28 of the intermediate portion 26 of the stator core 5, and the outer periphery 15 of the stator core 5 is located on both sides of the press-fit region B3 in the axial direction Z1. A pair of non-contact areas A2 and A3 are respectively formed.
In the second embodiment, by forming the pair of non-contact areas A2 and A3 at both ends of the stator core 5 that is the dust core P, stress due to press-fitting applied to both ends of the stator core 5 can be reduced. Therefore, durability of both ends of the stator core 5 can be improved.

FIG. 6 is a cross-sectional view schematically showing a schematic configuration of the electric motor 1 according to the third embodiment of the present invention. FIG. 7 is a part of a cross section taken along the line VII-VII of the electric motor 1 in FIG. FIG. 6 and FIG. 7, the same components as those shown in FIG. 1 and FIG. 2 described above are denoted by the same reference numerals as those in FIG. 1 and FIG.
6 and 7, the third embodiment is mainly different from the first embodiment in that a plurality of axial grooves 29 extending in the axial direction Z1 are formed on the outer periphery 15 of the stator core 5. There is. Specifically, each axial groove 29 is formed in the corresponding divided body 9 and extends from one end of the stator core 5 to the other end.

In a state where the stator core 5 is press-fitted into the frame 19, as shown in FIG. 7, a plurality of non-contact areas A 4 corresponding to the respective axial grooves 29 and a plurality of press-fit areas B 4 are formed on the outer periphery 15 of the stator core 5. The non-contact areas A4 and the press-fit areas B4 that are formed are alternately formed in the circumferential direction X1.
In the third embodiment, since a plurality of axial grooves 29 are formed on the outer periphery 15 of the stator core 5, stress caused by press-fitting can be uniformly dispersed in the stator core 5. The deterioration of characteristics can be suppressed.

  In the present embodiment, the case where each axial groove 29 is formed in the corresponding divided body 9 has been described. However, the plurality of axial grooves 29 can be arbitrarily arranged on the outer periphery 15 of the stator core 5 with respect to the circumferential direction X1. It may be formed in the position. That is, there may be a divided body 9 in which two or more axial grooves 29 are formed, or there may be a divided body 9 in which the axial grooves 29 are not formed. Further, the plurality of axial grooves 29 may be formed on the inner periphery 20a of the tubular portion 20 of the frame 19 instead of being formed on the outer periphery 15 of the stator core 5, and the stator core 5 may be formed as described above. Moreover, the dust core P and the laminated steel plate Q may be included.

The present invention is not limited to the contents of the above embodiments, and various modifications can be made within the scope of the claims. For example, in the above-described embodiment, the case where the stator core 5 is fixed to the frame 19 by press fitting is described. However, the stator core 5 may be fixed to the frame 19 by shrink fitting or other interference fitting.
In the above-described embodiment, the case where the stator core 5 is a divided stator core 5 divided in the circumferential direction X1 has been described. However, the stator core 5 is an integrated stator core 5 that is not divided in the circumferential direction X1. May be.

It is sectional drawing which shows typically schematic structure of the electric motor which concerns on 1st Embodiment of this invention. It is an expanded sectional view which shows a part of cross section which follows the II-II line | wire of the electric motor in FIG. It is sectional drawing which shows another form of the electric motor which concerns on 1st Embodiment of this invention. It is sectional drawing which shows another form of the electric motor which concerns on 1st Embodiment of this invention. It is sectional drawing which shows typically schematic structure of the electric motor which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows typically schematic structure of the electric motor which concerns on 3rd Embodiment of this invention. It is an expanded sectional view which shows a part of cross section which follows the VII-VII line of the electric motor in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electric motor, 5 ... Stator core, 6 ... Coil, 12 ... End part (a pair of edge part), 14 ... Groove, 15 ... Outer periphery (outer periphery of stator core), 16 , 16a ... annular recess (recess), 18 ... outer periphery (periphery of a pair of ends), 19 ... frame, 20a ... inner periphery (inner periphery of frame), 27 ... recess, 26 ... intermediate part, 28 ... outer periphery (outer periphery of intermediate part), 29 ... axial groove (recessed part), A1 to A4 ... non-contact area, B1, B2 ... press-fit area, P ... Dust core, Z1 ... Axial direction

Claims (5)

A cylindrical frame,
A coil is wound and an annular stator core press-fitted into the frame,
An electric motor characterized in that a non-contact region that is non-contact with each other is formed between an outer periphery of a stator core and an inner periphery of a frame. In claim 1, a recess is formed on at least one of the outer periphery of the stator core and the inner periphery of the frame,
The electric motor, wherein the non-contact region is formed corresponding to the recess. In Claim 1 or 2, the stator core includes a pair of end portions in the axial direction of the stator core, and an intermediate portion between the pair of end portions,
The non-contact region is formed on the outer periphery of the intermediate portion,
An electric motor, wherein a press-fitting region for a frame is formed on the outer periphery of the pair of end portions. In Claim 1 or 2, the stator core includes a pair of end portions in the axial direction of the stator core, and an intermediate portion between the pair of end portions,
The non-contact region is formed on the outer periphery of the pair of end portions. In Claim 3 or 4, the pair of ends of the stator core includes a dust core,
An electric motor, wherein the pair of ends are provided with coils winding grooves that open outward in the axial direction of the stator core.

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