JP2008092674A - Electric motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric motor capable of suppressing the decline of magnetic characteristics. <P>SOLUTION: The electric motor 1 is equipped with an annular stator core 8 and a coil 9 wound around the stator core 8. The stator core 8 includes first split cores 40 split into the axial direction Z1 and a pair of second split cores 41, wherein the end parts of the first split cores 40 are engaged with the engaging recessed parts 17 of the second split cores 41 arranged at the end parts. A part of the outer periphery 40a of the first split core 40 is covered with an outside extension part 16 which forms the outer peripheral wall of the engaging recessed parts 17. The stator core 8 is fixed to a housing 5 by press fitting or shrinkage fitting, with the first split cores 40 prevented from directly contacting to the housing 5, with the stress due to the press fitting or shrinkage fitting scattered to a pair of the second split cores 41. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electric motor.

Some electric motors include, for example, an annular stator core and a coil wound around the stator core. The stator core is usually held in a cylindrical housing.
For example, in Patent Document 1 below, the stator core is fixed in the housing by shrink fitting.
JP 2004-40948 A

However, when the stator core is fixed to the housing by shrink fitting or press fitting, stress due to the shrink fitting or the like 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.

  The present invention for achieving the above object includes a stator (4) including an annular stator core (8) and a coil (9) wound around the stator core, and a cylindrical housing (5) for holding the stator core. The stator core is formed by combining the first divided core (40) including the laminated steel plate and the second divided core (41 to 43) including the dust core, and the second divided core is the first divided core. Including a portion (16, 25, 28) that covers at least a part of the outer periphery (40a) of the cylindrical housing and is fitted to the inner periphery (18a) of the cylindrical housing, wherein the first divided core is formed by the second divided core. An electric motor (1) characterized by being held.

  According to the present invention, the first divided core and the housing are directly connected by fitting the second divided core holding the first divided core to the inner periphery of the housing, for example, by shrink fitting or press fitting. The stator core can be fixed to the housing without coming into contact with the housing. As a result, the stress caused by shrink fitting or press fitting can be dispersed in the second divided core, and the stress applied to the first divided core can be reduced. Therefore, it is possible to suppress a decrease in the magnetic characteristics of the stator core.

In the present invention, a pair of the second split cores may be provided, and the pair of second split cores (41) may sandwich the first split core in the axial direction (Z1) of the stator core. In this case, stress due to shrink fitting or press fitting is evenly distributed to the pair of second divided cores, so that the stress applied to the first divided core can be further reduced.
Moreover, in this invention, the 1st and 2nd division | segmentation core may be couple | bonded with the axial direction only by the winding force of the said coil. In this case, for example, the first and second divided cores may not be coupled by welding or press fitting. Therefore, since stress due to welding or press fitting is not applied to the first and second divided cores, it is possible to further suppress the deterioration of the magnetic characteristics of the stator core. In addition, since processes such as welding and press-fitting are not required, man-hours can be reduced.

  In the present invention, the second split core includes an outer cylinder portion (25) that covers the entire outer periphery of the first split core and is fitted to the inner periphery of the housing, and the first split core. An inner cylinder part (24) that covers the entire inner periphery (40b) and a pair of connection parts (26) that connect the outer cylinder part and the inner cylinder part to each other, and the first split core is formed by the pair of connection parts. In some cases, the stator core is sandwiched in the axial direction. In this case, the first split core is disposed between the outer cylinder portion and the inner cylinder portion, and the first split core is sandwiched between the pair of connecting portions in the axial direction, thereby allowing the inside of the second split core to be inside. The first divided core can be fixed and held securely.

  In the present invention, the second split core includes an outer cylindrical member (28) that covers the entire outer periphery of the first split core and is fitted to the inner periphery of the housing, and the first split core. An inner cylinder member (27) covering the entire inner periphery, and each of the outer cylinder member and the inner cylinder member may include a restricting portion (29) for restricting the axial movement of the first divided core. In this case, the first split core is moved between the outer cylinder member and the inner cylinder member while the first split core is moved in the axial direction by the restriction portions provided on each of the outer cylinder member and the inner cylinder member. By regulating, the first split core can be fixed and securely held within a predetermined range between the outer cylinder member and the inner cylinder member.

  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 of the electric motor 1 along the line II-II in FIG.
Referring to FIG. 1, an electric motor 1 according to the present embodiment is a brushless motor, and a cylindrical rotor 3 connected to a rotary shaft 2 so as to be integrally rotatable with the rotor 3 at a predetermined interval. An enclosing annular stator 4 and a cylindrical housing 5 that accommodates the rotor 3 and the stator 4 are provided.

  The rotor 3 includes a cylindrical rotor core 6 coaxially connected to the rotating shaft 2 and a plurality of permanent magnets 7 held on the outer periphery of the rotor core 6. Although not shown, the plurality of permanent magnets 7 are arranged at a predetermined interval in the circumferential direction of the rotor 3, and the outer circumference of the rotor 3 is a magnetic pole in which the N pole and the S pole are alternately switched in the circumferential direction of the rotor 3. It has become. The rotor core 6 is integrally formed of a single material.

Referring to FIGS. 1 and 2, stator 4 includes an annular stator core 8 and a coil 9 wound around stator core 8.
The stator core 8 includes an annular yoke 10 and a plurality of teeth 11 protruding from the inner periphery of the yoke 10 toward the inside of the stator core 8 in the radial direction X1.
As shown in FIG. 2, the plurality of teeth 11 are annularly arranged at equal intervals in the circumferential direction Y1 of the stator core 8, and each tooth 11 has a T-shaped cross section. That is, each tooth 11 is connected to the first portion 12 as a radially extending portion extending inward in the radial direction X1 from the inner periphery of the yoke 10 and the tip portion of the first portion 12, and is concentric with the yoke 10. And a second portion 13 as a circumferentially extending portion that extends along a circle that forms a circle.

As shown in FIG. 1, the stator core 8 includes a first divided core 40 and a pair of second divided cores 41 as axially divided bodies that are divided in the axial direction Z1 of the stator core 8.
The first split core 40 is composed of a laminated steel plate in which a plurality of electromagnetic steel plates are laminated and fixed in the axial direction Z1, and the second split core 41 is formed of a powder material containing a soft magnetic material. It is composed of a dust core.

  Specifically, the dust core is a magnetic core obtained by compression-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. Moreover, as said electromagnetic steel plate, the silicon steel plate etc. by which the insulation process was given to the surface can be used, for example. The plurality of electromagnetic steel sheets are laminated and fixed by, for example, caulking or welding.

Further, the pair of second divided cores 41 are respectively disposed at the end portions of the first divided core 40 with respect to the axial direction Z1, and the end surfaces of the second divided cores 41 on the outer side in the axial direction Z1 are disposed on the end surfaces. A coil receiving groove 14 for winding a coil extending in the circumferential direction Y1 is formed.
In addition, an annular inner extending portion 15 and an outer extending portion 16 extending toward the inner side in the axial direction Z1 are provided on the end surface on the inner side in the axial direction Z1 of each second split core 41. Yes. A fitting recess 17 into which the first split core 40 is fitted is formed between the inner extending portion 15 and the outer extending portion 16.

  That is, as shown in FIGS. 1 and 2, the inner extending portion 15 extends from the inner peripheral edge portion (corresponding to a part of the second portion 13 of the tooth 11) of the end surface on the inner side in the axial direction Z <b> 1. The outer extending portion 16 extends from the outer peripheral edge portion (corresponding to a part of the yoke 10) of the end surface on the inner side in the axial direction Z1. Accordingly, the inner extending portion 15 and the outer extending portion 16 are opposed to each other at a predetermined interval in the radial direction X1.

The first split core 40 is shorter in the radial direction X1 than the second split core 41, and each end of the first split core 40 is disposed at the end as shown in FIG. The second split core 41 is fitted in the fitting recess 17. As a result, the first divided core 40 is held between the pair of second divided cores 41 in the axial direction Z1.
Further, in a state where the first divided core 40 is fitted in the fitting recess 17, a part of the outer periphery 40 a of the first divided core 40 is covered by the outer extending portion 16 of each second divided core 41. In addition, a part of the inner periphery 40 b of the first divided core 40 is covered with the inner extending portion 15 of each second divided core 41.

As will be described later, the outer extending portion 16 is fitted and fixed to the inner circumference 18a of the cylindrical housing 5 by shrink fitting or press fitting, for example. That is, the outer extending portion 16 constitutes a portion that covers a part of the outer periphery 40 a of the first divided core 40 and is fitted to the inner periphery 18 a of the cylindrical housing 5.
As shown in FIGS. 1 and 2, the coil 9 is wound along the first portion 12 of each tooth 11. A part of the coil 9 wound around each tooth 11 is accommodated in a coil accommodation groove 14 corresponding to the tooth 11. In a state where the coil 9 is wound around each tooth 11, the first split core 40 and the pair of second split cores 41 are coupled in the axial direction Z <b> 1 by the winding force of the coil 9. Thereby, the first split core 40 can be reliably held by the pair of second split cores 41.

Referring again to FIG. 1, the housing 5 is formed of a metal such as iron, for example, and includes a cylindrical portion 18 and a pair of end walls 19 and 20 disposed at the ends of the cylindrical portion 18. . In the present embodiment, one of the pair of end walls 19 and 20 (end wall 19) and the cylindrical portion 18 are integrally formed of a single material.
The stator core 8 is fixed to the cylindrical portion 18 by being fitted to the inner periphery 18a of the cylindrical portion 18 by, for example, shrink fitting or press fitting. Specifically, a pair of second split cores 41 holding the first split core 40 are fitted to the inner periphery 18a of the cylindrical portion 18 by, for example, shrink fitting or press fitting, and the outer extension The stator core 8 is fixed to the cylindrical portion 18 in a state where the outer periphery of each second split core 41 including the outer periphery of the installation portion 16 is in contact with the inner periphery 18 a of the cylindrical portion 18. At this time, a predetermined interval is provided between the cylindrical portion 18 and the first divided core 40, and the cylindrical portion 18 and the first divided core 40 are not in direct contact with each other. ing.

In addition, insertion holes 21 through which the rotation shaft 2 is inserted are formed in the center portions of the pair of end walls 19 and 20, respectively. Each insertion hole 21 is formed with a bearing holding portion 23 that holds the bearing 22, and the rotary shaft 2 is rotatably held by the housing 5 via the bearing 22 held by the bearing holding portion 23. .
As described above, in the first embodiment, the outer extending portion 16 that covers a part of the outer periphery 40a of the first split core 40 and is fitted to the inner periphery 18a of the cylindrical housing 5 is provided. Provided. Thereby, the second split core 41 is fitted to the cylindrical portion 18 without directly contacting the first split core 40 and the cylindrical portion 18 of the housing 5, and the stator core 8 is fixed to the housing 5. can do. As a result, it is possible to reduce the stress applied to the first divided core 40 by dispersing stress due to shrink fitting or press fitting into the second divided core 41. Therefore, the loss torque of the electric motor 1 can be reduced by suppressing the deterioration of the magnetic characteristics of the stator core 8 due to the stress.

  Further, since the first divided core 40 and the pair of second divided cores 41 are coupled by the winding force of the coil 9, the first and second divided cores 40 and 41 are coupled by, for example, welding or press fitting. It does not have to be. Therefore, since stress due to welding or press fitting is not applied to the first and second split cores 40 and 41, it is possible to further suppress the deterioration of the magnetic characteristics of the stator core 8. In addition, since processes such as welding and press-fitting are not required, man-hours can be reduced.

In the first embodiment, the example in which a part of the inner circumference 40b and the outer circumference 40a of the first divided core 40 is covered by the pair of second divided cores 41 has been described. The core 41 may cover the entire inner periphery 40b and outer periphery 40a of the first divided core 40.
FIG. 3 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. 3, the same components as those shown in FIGS. 1 and 2 described above are denoted by the same reference numerals as those in FIGS. 1 and 2, and the description thereof is omitted.

Referring to FIG. 3, the second embodiment is mainly different from the first embodiment described above in that the stator core 8 includes a first divided core 40 and a single second divided core 42. The first divided core 40 is embedded in the second divided core 42.
That is, all surfaces including the inner periphery 40 b and the outer periphery 40 a of the first divided core 40 are covered with the second divided core 42. The second split core 42 covers the entire inner periphery 40 b of the first split core 40 and the entire outer periphery 40 a of the first split core 40 and covers the entire outer periphery 40 a of the cylindrical housing 5. The outer cylinder part 25 as a part fitted by the inner periphery 18a and a pair of connection part 26 which connects the inner cylinder part 24 and the outer cylinder part 25 are included.

  Each of the inner cylinder part 24 and the outer cylinder part 25 has substantially the same axial length as the rotor 3 and is disposed opposite to the radial direction X1 at a predetermined interval. Each connection part 26 has connected the edge part of the inner cylinder part 24 and the outer cylinder part 25 regarding the axial direction Z1. Although not shown, each connecting portion 26 is divided in the circumferential direction Y1 for each tooth 11. The first split core 40 is disposed between the inner cylinder portion 24 and the outer cylinder portion 25 and is sandwiched between the pair of connecting portions 26 in the axial direction Z1.

  Further, the adjacent magnetic steel sheets of the laminated steel sheets constituting the first divided core 40 are not fixed to each other by caulking, welding, or the like, and their relative positions are fixed by the holding force of the second divided core 42. Yes. That is, a plurality of electromagnetic steel plates of the laminated steel plates constituting the first divided core 40 are arranged in a mold in a laminated state when the second divided core 42 is formed, and the second divided core 42 is Each of the relative positions is fixed by press-molding together with the above-described powder material.

Thereby, since it is not necessary to fix a plurality of electromagnetic steel sheets by caulking or welding, it is possible to prevent the stress due to caulking or welding from being applied to the first and second split cores 40 and 42, 8 can be suppressed.
Further, the interval in the radial direction X1 between the stator core 8 and the rotor 3 is constant over the axial direction Z1, and the stator core 8 is configured such that the entire outer periphery of the second divided core 42 is the inner periphery of the cylindrical portion 18. It is being fixed to the housing 5 in the state which contacted 18a.

  As described above, in the second embodiment, by embedding the first divided core 40 in the second divided core 42, the first divided core 40 is securely fixed in the second divided core 42. Can be retained. Therefore, the relative positions of the plurality of electromagnetic steel plates included in the first divided core 40 can be fixed without using caulking or welding. Thereby, the fall of the magnetic characteristic of the stator core 8 can be suppressed.

Further, since the outer periphery of the second split core 42 and the inner periphery 18a of the cylindrical portion 18 of the housing 5 can be brought into contact with each other over the axial length of the stator core 8, the stator core 8 is fixed to the housing 5 more firmly. can do.
In the second embodiment, the example in which the entire surface of the first divided core 40 is covered with the second divided core 42 has been described. However, the surface that is not covered with the second divided core 42 ( However, at least a part of the outer periphery of the first split core 40 may be covered.)

FIG. 4 is a cross-sectional view schematically showing a schematic configuration of the electric motor 1 according to the third embodiment of the present invention. 4, the same components as those shown in FIGS. 1 to 3 described above are denoted by the same reference numerals as those in FIGS.
Referring to FIG. 4, the third embodiment is mainly different from the second embodiment described above in that the second divided core 43 has the entire inner periphery 40 b of the first divided core 40. It is divided into an inner cylinder member 27 to be covered and an outer cylinder member 28 that covers the entire outer periphery 40a of the first divided core 40 and is fitted to the inner periphery 18a of the cylindrical housing 5. That is, the axial movement of the first split core 40 is restricted by the stepped portion 29 as the restricting portion formed on each of the cylindrical member 27 and the outer cylindrical member 28.

  That is, a fitting recess 30 slightly longer than the axial length of the first split core 40 is formed along the circumferential direction Y1 on the outer periphery of the inner cylinder member 27 and the inner periphery of the outer cylinder member 28. One split core 40 is fitted in a fitting recess 30 formed in the inner cylinder member 27 and the outer cylinder member 28. Further, the axial movement of the first split core 40 is such that the stepped portion 29 as a restricting portion provided at each end of each fitting recess 30 in the axial direction Z1 causes the first split core 40 in the axial direction Z1 to move. It is regulated by abutting against the end face of the. In this way, the first split core 40 is fixed and held in a predetermined range between the inner cylinder member 27 and the outer cylinder member 28.

Further, the interval in the radial direction X1 between the stator core 8 and the rotor 3 is constant over the axial direction Z1, and the stator core 8 is configured such that the entire outer periphery of the second divided core 43 is the inner periphery of the cylindrical portion 18. It is being fixed to the housing 5 in the state which contacted 18a.
As described above, in the third embodiment, the first divided core 40 is disposed between the inner cylindrical member 27 and the outer cylindrical member 28 of the second divided core 43, and the axial movement thereof is used as a restricting portion. By restricting by the step portion 29, the first divided core 40 can be fixed and held in a predetermined range between the inner cylinder member 27 and the outer cylinder member 28. Thereby, each relative position can be fixed, without fixing the several electromagnetic steel plate of the laminated steel plate which comprises the 1st division | segmentation core 40 by caulking or welding. As a result, it is possible to suppress a decrease in the magnetic characteristics of the stator core 8.

Moreover, since the 1st division | segmentation core 40 comprised with the laminated steel plate with a hysteresis loss smaller than a powder magnetic core can be enlarged compared with the above-mentioned 2nd Embodiment, the loss torque of the electric motor 1 can be reduced. Can do.
FIG. 5 is a cross-sectional view schematically showing a schematic configuration of the electric motor 1 according to the fourth embodiment of the present invention. 5, the same components as those shown in FIG. 1, FIG. 2, and FIG. 4 described above are denoted by the same reference numerals as those in FIG. 1, FIG. 2, and FIG. .

Referring to FIG. 5, the fourth embodiment is mainly different from the third embodiment described above as a coupling member that couples the cylindrical portion 18 of the housing 5 and the second divided core 43. The stator core 8 is fixed to the housing 5 by the plurality of bolts 31.
Specifically, a plurality of insertion holes 32 through which the respective bolts 31 are inserted are formed in the cylindrical portion 18 of the housing 5, and the bolts 31 are provided on the outer periphery of the outer cylindrical member 28 of the second divided core 43. A plurality of screw holes 33 into which are screwed are formed.

The stator core 8 is a housing in which the bolts 31 are inserted into the corresponding insertion holes 32 in the state in which the positions of the insertion holes 32 and the screwing holes 33 are matched, and are screwed into the corresponding screwing holes 33. 5 is fixed.
As described above, in the fourth embodiment, the stator core 8 can be fixed to the housing 5 without using shrink fitting or press fitting. Therefore, it is possible to prevent stress due to shrink fitting, press fitting, or the like from being applied to the stator core 8, so that it is possible to more reliably suppress the deterioration of the magnetic properties of the stator core 8.

In addition, the plurality of screw holes 33 into which the bolts 31 are screwed are formed in the second split core 43 formed of a dust core having a relatively high degree of freedom in shape, and thus can be easily formed. .
The present invention is not limited to the contents of the first to fourth embodiments described above, and various modifications can be made within the scope of the claims. For example, in the above-described first to fourth embodiments, an example in which the stator core 8 is an integrated stator core 8 that is not divided in the circumferential direction Y1 has been described. However, the stator core 8 is divided into a plurality of teeth 11 divided into teeth 11. You may be comprised by the circumferential direction division body.

In the first to fourth embodiments described above, the example in which the rotor core 6 is formed from a single material has been described. However, the rotor core 6 is configured by a plurality of members formed from different materials. Also good.
For example, the rotor core 6 may be constituted by the laminated steel plate and the dust core. In this case, similarly to the first and second divided cores 40 and 42 in the second embodiment, the laminated steel plates are embedded in the dust core, and a plurality of laminated steel plates are laminated by the holding force of the dust core. May be fixed.

It is sectional drawing which shows typically schematic structure of the electric motor which concerns on the 1st Embodiment of this invention. It is an expanded sectional view which shows a part of cross section of the electric motor which follows the II-II line in FIG. It is sectional drawing which shows typically schematic structure of the electric motor which concerns on the 2nd Embodiment of this invention. It is sectional drawing which shows typically schematic structure of the electric motor which concerns on the 3rd Embodiment of this invention. It is sectional drawing which shows typically schematic structure of the electric motor which concerns on the 4th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electric motor, 4 ... Stator, 5 ... Housing, 8 ... Stator core, 9 ... Coil, 16 ... Outer extension part (At least one of the outer periphery of a 1st division | segmentation core) 18a ... inner circumference (inner circumference of housing), 24 ... inner cylinder part, 25 ... outer cylinder part, 26. ..Connecting portion, 27... Inner cylindrical member, 28... Outer cylindrical member, 29... Stepped portion (regulating portion), 40. Of outer divided cores), 40b ... inner circumference (inner circumference of first divided core), 41-43 ... second divided core, 41 ... second divided core (a pair of second cores) Split core), Z1... Axial direction (axial direction of stator core)

Claims (5)

A stator including an annular stator core and a coil wound around the stator core;
A cylindrical housing for holding the stator core,
The stator core is formed by combining a first divided core including a laminated steel plate and a second divided core including a dust core,
The second split core includes a portion that covers at least a part of the outer periphery of the first split core and is fitted to the inner periphery of the cylindrical housing,
An electric motor, wherein the first divided core is held by the second divided core.   2. The electric motor according to claim 1, wherein a pair of the second divided cores are provided, and the pair of second divided cores sandwich the first divided core in the axial direction of the stator core.   3. The electric motor according to claim 2, wherein the first and second split cores are coupled in the axial direction only by the winding force of the coil.   In Claim 1, The said 2nd division | segmentation core covers the whole outer periphery of a 1st division | segmentation core, and the outer cylinder part fitted to the inner periphery of the said housing, and the whole inner periphery of a 1st division | segmentation core And a pair of connecting parts that connect the outer cylinder part and the inner cylinder part to each other, and the first split core is sandwiched in the axial direction of the stator core by the pair of connecting parts. Electric motor to do.   In Claim 1, The said 2nd division | segmentation core covers the whole outer periphery of a 1st division | segmentation core, and is fitted to the inner periphery of the said housing, The whole inner periphery of a 1st division | segmentation core And an inner cylinder member that covers the inner cylinder member, and each of the outer cylinder member and the inner cylinder member includes a restricting portion that restricts axial movement of the first divided core.

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