JP2015126545A - Electric motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric motor capable of maintaining a fixed state between a stator and a steel plate bracket while preventing generation of electric corrosion in bearings.SOLUTION: An electric motor includes: a stator 1 including a stator core 11 whose outer periphery is covered with an insulating member 12; a rotor rotatably arranged on the inner peripheral side of the stator 1; bearings for respectively supporting the output side and the counter output side of a shaft of the rotor; and a steel plate bracket 5 for holding the bearings and storing and fixing the stator 1. A plurality of projections 514 are formed on an inner peripheral surface 515 of the steel plate bracket 5 and a plurality of recesses 121 with which the plurality of projections 514 are to be engaged are formed on an outer peripheral surface 122 of the stator 1.

Description

  The present invention relates to an electric motor having a stator fixed to a steel plate bracket.

  A conventional electric motor includes an inner rotor type electric motor in which a rotor is rotatably disposed inside a stator, and is used, for example, as a brushless DC motor for rotationally driving a blower fan mounted on an air conditioner. This electric motor has, for example, a structure in which a stator is press-fitted into a steel plate bracket having a bearing house, and the steel plate bracket and the stator core are in direct contact with each other to be conducted. For this reason, when the potential of the stator core is increased, the potential difference between the steel plate bracket and the shaft of the motor supported by the bearing is increased, and there is a possibility that electrolytic corrosion occurs in the bearing. As a countermeasure, an insulating member may be interposed between the steel plate bracket and the stator core. Since the steel plate bracket and the stator core become non-conductive due to the presence of an insulating member, the potential difference between the steel plate bracket and the shaft does not increase even when the potential of the stator core increases, and the occurrence of electrolytic corrosion on the bearing is prevented. Can do.

  By the way, the structure which interposed the vibration isolator which prevents the vibration of a motor between the steel plate bracket and the stator core is known for the conventional electric motor. This anti-vibration member is a buffer portion that bulges from the end face of the insulator that covers the outer periphery of the stator core (see, for example, Patent Document 1). Therefore, since this buffer part can also be used as an insulating member between the steel plate bracket and the stator core, it can also serve as a member for preventing the occurrence of electrolytic corrosion on the bearing.

  However, in the case of a structure in which the outer periphery of the stator core is covered with a resin member such as an insulator, if the stator is press-fitted into the steel plate bracket and fixed, the elastic force of the resin member will deteriorate due to aging and the stator will continue to be fixed to the steel plate bracket There was a risk of being lost.

JP 2002-101606 A

  In view of the above problems, an object of the present invention is to provide an electric motor that maintains a fixed state between a stator and a steel plate bracket while preventing the occurrence of electrolytic corrosion on a bearing.

  In order to solve the above problems, an electric motor according to the present invention includes a stator having a stator core whose outer periphery is covered with an insulating member, a rotor rotatably disposed on the inner peripheral side of the stator, and an output side of a shaft of the rotor. The bearing includes a bearing that supports each of the non-output sides, and a steel plate bracket that holds the bearing and holds and fixes the stator, and a plurality of protrusions are formed on the inner peripheral surface of the steel plate bracket. A plurality of recesses into which a plurality of projecting portions are respectively fitted are formed on the outer peripheral surface of the.

  In the electric motor of the present invention, the steel plate bracket includes two steel plate bracket pieces divided in the axial direction of the shaft, the steel plate bracket pieces are formed with bearing houses on the respective bottom surfaces, and at least one of the steel plate bracket pieces is a cylinder. The stator is inserted into the steel plate bracket piece along the axial direction of the shaft, and the outer peripheral surface of the stator is inserted in the insertion direction on the outer peripheral surface continuous with the concave portion in the stator insertion direction. A tapered portion is formed such that the outer diameter decreases toward the end.

  Further, in the electric motor of the present invention, three or more fitting portions constituted by the concave portion and the protruding portion are at the same height in the axial direction from the bottom surface of one steel plate bracket piece and at equal intervals in the circumferential direction. The protruding portion is characterized in that the stator core side wall of the stator is pressed in the radial direction via the recess.

  According to the electric motor of the present invention, the steel plate bracket that holds the bearing and holds and fixes the stator is provided, and the plurality of protrusions are formed on the inner peripheral surface of the steel plate bracket, and the plurality of protrusions are formed on the outer peripheral surface of the stator. By forming the plurality of recesses into which the parts are respectively fitted, it is possible to maintain the fixed state between the stator and the steel plate bracket while preventing the occurrence of electrolytic corrosion on the bearing.

  Further, according to the electric motor of the present invention, the outer peripheral surface of the stator is formed with a tapered portion whose outer diameter decreases in the insertion direction on the outer peripheral surface that is continuous with the recess in the insertion direction of the stator. Therefore, the stator can be easily inserted into the steel plate bracket.

  Further, according to the electric motor of the present invention, three or more fitting portions constituted by the concave portion and the protruding portion are at the same height in the axial direction from the bottom surface of one steel plate bracket piece and at equal intervals in the circumferential direction. The protrusions are disposed and the air gap is made uniform by pressing the stator core side wall of the stator in the radial direction via the recesses.

It is a schematic sectional drawing which shows the electric motor by this invention. It is an external appearance perspective view which shows the state which accommodated and fixed the stator to the steel plate bracket piece of the non-output side of the electric motor by this invention. FIG. 3 is a top view of the electric motor according to the present invention shown in FIG. 2. It is AA sectional drawing shown in FIG. 3 of the electric motor by this invention, (a) is whole sectional drawing, (b) is a fragmentary sectional view.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. 1 to 4 are diagrams illustrating the electric motor according to the present embodiment. 1 is a schematic cross-sectional view including a cross-sectional view taken along the line BB shown in FIG. The electric motor in the embodiment is an inner rotor type electric motor in which a rotor is rotatably arranged on the inner peripheral side of a stator that generates a rotating magnetic field. For example, a brushless DC motor for rotationally driving a blower fan mounted on an air conditioner Used as

  As shown in FIGS. 1 to 3, the electric motor M includes a stator 1 including a stator core 11 whose outer periphery is covered with an insulating member 12, a rotor 2 that is rotatably disposed on the inner peripheral side of the stator 1, and a rotor A bearing 41 that supports the opposite output side of the shaft 3 of the shaft 2, a bearing 42 that supports the output side of the shaft 3 of the rotor 2, and a steel plate bracket that holds the two bearings 41 and 42 and accommodates and fixes the stator 1. And 5.

  The stator core 11 is formed in a cylindrical shape by laminating a plurality of thin steel plates, and includes an annular back yoke portion 111 and a plurality of teeth portions 112 extending from the back yoke portion 111 to the inner diameter side. An insulating member 12 is integrally formed on the stator core 11, and a stator winding 13 is wound around the tooth portion 112 via the insulating member 12. The insulating member 12 is formed of a resin such as PBT, PET, or unsaturated polyester, and covers the stator core 11 except for the front end surface 1121 of the teeth portion 112 (the inner peripheral surface of the stator core 11). The stator 1 configured as described above is fixed to the steel plate bracket 5 so that the front end surface 1121 of the tooth portion 112 faces the outer peripheral surface 21 of the rotor 2 with a predetermined interval (so-called air gap).

  The steel plate bracket 5 includes two steel plate bracket pieces 51 and 52 divided in the axial direction of the shaft 3. A steel plate bracket piece 51 is provided on the opposite side of the shaft 3 and a steel plate bracket piece 52 is provided on the output side of the shaft 3. The steel plate bracket piece 51 on the opposite output side is formed in a bottomed cylindrical shape. The stator 1 is inserted into the steel plate bracket piece 51 along the axial direction of the shaft 3. At the center of the bottom surface 511 of the steel plate bracket piece 51, a bottomed cylindrical bearing house 512 having a smaller diameter than the bottom surface 511 and protruding in the axial direction is formed, and the bearing 41 is held by the bearing house 512. The steel plate bracket piece 51 and the bearing 41 are in direct contact with each other via the bearing house 512 and are electrically connected.

  The steel plate bracket piece 52 on the output side is formed in a bottomed cylindrical shape shallower than the steel plate bracket piece 51, and the inner peripheral surface 523 of the steel plate bracket piece 52 is fitted to the outer peripheral surface 513 of the steel plate bracket piece 51. At the center of the bottom surface 521 of the steel plate bracket piece 52, a bottomed cylindrical bearing house 522 having a smaller diameter than the bottom surface 521 and protruding in the axial direction is formed, and the bearing 42 is held by the bearing house 522. The steel plate bracket piece 52 and the bearing 42 are in direct contact with each other via the bearing house 522 and are electrically connected. The steel plate bracket 5 includes two steel plate bracket pieces 51 and 52 having a bottomed cylindrical shape. However, the present invention is not limited to this, and one of them is a bottomed cylindrical steel plate bracket piece and the other is a disc shape. It is good also as a steel plate bracket piece.

  As shown in FIGS. 3 and 4, the electric motor M is provided with a fitting portion 6 for accommodating and fixing the stator 1 to the steel plate bracket 5 as a characteristic portion of the present invention. Four fitting portions 6 are formed on the inner peripheral surface 515 of the steel plate bracket piece 51 and four protrusion portions 514 are formed on the outer peripheral surface 122 of the stator 1, and the concave portions 121 into which the four protrusion portions 514 are respectively fitted. It consists of and. When the electric motor M is assembled, the stator 1 is inserted from the opening 516 of the steel plate bracket piece 51 toward the bottom surface 511. When the stator 1 is inserted to a position where the concave portion 121 faces the protruding portion 514, the stator 1 is fixed to the steel plate bracket 5 by the fitting portion 6 constituted by the protruding portion 514 and the concave portion 121. The

  Four fitting portions 6 of the present embodiment are further arranged at the same height H in the axial direction from the bottom surface 511 of the steel plate bracket piece 51 and at equal intervals in the circumferential direction of the steel plate bracket piece 51. . Further, the four protruding portions 514 formed on the steel plate bracket piece 51 are formed so as to protrude from the inner peripheral surface 515 of the steel plate bracket piece 51 by the same height L in the radial direction. The four protrusions 514 respectively hold the stator core side wall 113 of the stator 1 in the radial direction via the recesses 121. On the other hand, each of the four recesses 121 formed in the stator 1 has a small thickness in the radial direction of the insulating member 12, so that the insulating state between the steel plate bracket piece 51 and the stator core 11 is maintained and the stator core side wall is maintained. 113 can be brought close to a state where it is directly pressed by the four protrusions 514. As a result, the radial distance between the inner peripheral surface 515 of the steel plate bracket piece 514 and the stator core side wall 113 can be made uniform over the entire circumference, and the central axis O of the rotor 2 (see FIG. 1) and the stator 1 The center axis O ′ can be matched with high accuracy, and the radial gap distance (so-called air gap) between the tip surface 1121 of the tooth portion 112 and the outer peripheral surface 21 of the rotor 2 becomes uniform. Thereby, when the electric motor M is driven, the rotational torque applied to the outer peripheral surface 21 of the rotor 2 is not uneven, and the efficiency of the electric motor M can be increased. In addition, the air gap can be made narrower.

  Further, of the outer peripheral surface 122 of the insulating member 12 of the stator 1, an outer diameter 1221 that is continuous with the wall surface 1211 of the recess 121 in the insertion direction of the stator 1 has a smaller outer diameter in the insertion direction of the stator 1. Such a tapered portion 1222 is formed. Therefore, when the stator 1 is inserted into the steel plate bracket piece 51, the taper portion 1222 can reduce mechanical resistance such as friction. As a result, the protrusion 514 is easily fitted in the recess 121, and the stator 1 can be easily inserted into the steel plate bracket piece 51.

  According to the electric motor M according to the embodiment described above, the steel plate bracket piece 51 that holds the bearing 41 and accommodates and fixes the stator 1 is provided, and four protrusions 514 are provided on the inner peripheral surface 515 of the steel plate bracket piece 51. Are formed on the outer circumferential surface 122 of the insulating member 12 of the stator 1. As a result, the insulating member 12 is interposed between the steel plate bracket piece 51 and the stator core 11 so that the steel plate bracket piece 51 and the stator core 11 become non-conductive, so that it is possible to prevent electrolytic corrosion from occurring in the bearings 41 and 42. it can. Furthermore, the fixing state of the stator 1 and the steel plate bracket piece 51 can be maintained by fitting the recess 121 of the stator 1 to the protruding portion 514 of the steel plate bracket piece 51.

  Further, according to the electric motor M according to the present embodiment, the steel plate bracket piece 51 is formed in a cylindrical shape, and the stator 1 is inserted into the steel plate bracket piece 51 along the axial direction of the shaft 3. Of these, a tapered portion 1222 having an outer diameter that decreases in the insertion direction is formed on the outer peripheral surface 1221 that is continuous with the recess 121 in the insertion direction of the stator 1. As a result, the stator 1 can be easily inserted into the steel plate bracket piece 51. When the stator 1 is inserted into the steel plate bracket piece 51, for example, it is easier to insert the lubricant by applying a lubricant to the outer peripheral surface 122 of the stator 1 in advance. The protruding portion 514 of the steel plate bracket piece 51 rides over the edge 1223 where the wall surface 1211 of the concave portion 121 of the stator 1 and the outer peripheral surface 1221 of the tapered portion 1222 intersect with each other, and is thus fitted into the concave portion 121 of the stator 1. It is difficult to remove from the steel plate bracket piece 51 in the direction opposite to the insertion direction.

  Furthermore, according to the electric motor M according to the present embodiment, the fitting portion 6 constituted by the concave portion 121 and the protruding portion 514 has the same height H from the bottom surface 511 of the steel plate bracket piece 51 in the axial direction and in the circumferential direction. Four of the four protruding portions 514 are arranged at equal intervals so as to protrude from the inner peripheral surface 515 of the steel plate bracket piece 51 by the same height L in the radial direction. The stator core side wall 113 of the stator 1 is pressed in the radial direction. As a result, as described above, the central axis O of the rotor 2 and the central axis O 'of the stator 1 can be made to coincide with each other with high accuracy, and the air gap is made uniform. In the present embodiment, four fitting parts 6 are arranged. However, the present invention is not limited to this, and the effect of making the air gap uniform can be obtained by arranging at least three fitting parts.

  In the electric motor M according to the present embodiment described above, the stator 1 is inserted along the axial direction of the shaft 3 into the steel plate bracket piece 51 on the opposite output side of the shaft 3, but the present invention is not limited to this, and the shaft The stator 1 may be inserted along the axial direction of the shaft 3 into the output-side steel plate bracket piece 52. Moreover, the fitting part 6 comprised by the recessed part 121 and the protrusion part 514 also serves as the stopper function to the circumferential direction, and can prevent idling of the stator 1 with respect to the steel plate bracket piece 51.

DESCRIPTION OF SYMBOLS 1 Stator 11 Stator core 111 Back yoke part 112 Teeth part 113 Stator core side wall 1121 Front end surface 12 Insulation member 121 Recess 1211 Wall surface 122 Outer surface 1221 Outer surface 1222 Tapered part 1223 Edge 2 Rotor 21 Outer surface 3 Shaft 41 Bearing 42 Bearing 5 Steel plate bracket 51 Steel plate bracket piece 511 Bottom surface 512 Bearing house 513 Outer peripheral surface 514 Protruding portion 515 Inner peripheral surface 516 Opening 52 Steel plate bracket piece 521 Bottom surface 522 Bearing house 523 Inner peripheral surface 6 Fitting portion M Electric motor H Axis direction from bottom surface 511 of steel plate bracket piece 51 Height L Radial length of protrusion 514 O Center axis of rotor 2 O ′ Center axis of stator 1

Claims (3)

  A stator including a stator core whose outer periphery is covered with an insulating member, a rotor rotatably disposed on the inner peripheral side of the stator, bearings that respectively support the output side and the non-output side of the shaft of the rotor, An electric motor comprising a steel plate bracket that holds and fixes the stator while holding a bearing, wherein a plurality of protrusions are formed on an inner peripheral surface of the steel plate bracket, and the plurality of protrusions are formed on an outer peripheral surface of the stator. A plurality of recesses into which the protruding portions of the motors respectively fit are formed.   The steel plate bracket includes two steel plate bracket pieces divided in the axial direction of the shaft, the steel plate bracket piece is formed with a bearing house on each bottom surface, at least one steel plate bracket piece is formed in a cylindrical shape, The stator is inserted in the one steel plate bracket piece along the axial direction of the shaft, and the outer circumferential surface of the stator is inserted in the insertion direction on the outer circumferential surface continuous with the recess toward the insertion direction of the stator. The electric motor according to claim 1, wherein a tapered portion is formed such that the outer diameter decreases toward the front.   Three or more fitting parts constituted by the recesses and the protrusions are arranged at the same height in the axial direction from the bottom surface of the one steel plate bracket piece and at equal intervals in the circumferential direction, and the protrusions are The electric motor according to claim 2, wherein a stator core side wall of the stator is pressed in a radial direction through the recess.

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