JP5370686B2 - Brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brushless motor capable of preventing deterioration of magnetic characteristics of a stator core due to press fitting even when a stator core is press fitted into a case, and reducing loss torque. <P>SOLUTION: The brushless motor 1 includes a stator 9, which has a stator core 7 and a coil 8 wound around the stator core 7, and a case 2A housing the stator 9. The stator core 7 has a structure in which multiple magnetic steel sheets 71 to 75, each of which has different outer diameters, are laminated, and the stator core 7 is inserted into the case 2A. The stator core 7 is press fitted into the case 2A to join thereto. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to a brushless motor, and more particularly to an improvement of a brushless motor suitably used in an electric power steering apparatus.

  Conventionally, in order to reduce loss torque of an electric power steering (hereinafter referred to as “EPS”) motor, the hysteresis loss per frequency of 1 Hz when magnetized to a maximum magnetic flux density of 1.5 T is 0.10 J / kg or less. A technology using electromagnetic steel sheets for motor cores has been introduced. (For example, refer to Patent Document 1).

  Moreover, the hysteresis loss characteristics are improved by performing heat treatment on the electromagnetic steel sheet for EPS motor core so that the slab heating temperature during hot rolling is 1050 to 1180 ° C, and more preferably, the annealing temperature during magnetic annealing is 720 to 900 ° C. Technology to reduce loss torque is also introduced. (For example, refer to Patent Document 2).

  And a stator core in which a ring-shaped core piece formed by forming an electromagnetic steel sheet is laminated, the electromagnetic steel sheet having magnetic anisotropy by rolling, and rolling of core pieces adjacent in the vertical direction of the lamination An EPS motor has also been introduced that reduces loss torque by laminating the core pieces so that the directions differ by a predetermined angle. (For example, refer to Patent Document 3).

  A stator iron core comprising an annular stator yoke portion and a plurality of stator salient poles formed separately from the stator yoke portion and fixed to the stator yoke portion. In addition, an EPS motor that reduces loss torque by using an amorphous iron core as the iron core of the stator salient pole is also introduced. (For example, refer to Patent Document 4).

  Still further, the stator unit includes a stator core accommodated in a case, and a rotor that is rotatable with respect to the stator unit, and the stator core and the case are fixed by a protruding portion that protrudes to receive a load. In addition, an EPS motor that reduces loss torque by introducing a structure in which the stator core and the case are not in contact with each other except for the protrusion is also introduced. (For example, refer to Patent Document 5).

JP 2001-11585 A JP 2001-335843 A JP 2004-350369 A JP 2005-253168 A JP 2006-333657 A

  However, the electromagnetic steel sheet for EPS motor core described in Patent Document 1 has good magnetic characteristics of the material itself constituting the electromagnetic steel sheet, but when the stator core is press-fitted into the case, the magnetic characteristics of the stator core are affected by the press-fitting. It is difficult to obtain sufficient characteristics such as deterioration and iron loss. Further, Patent Documents 2 to 4 do not describe a method of disposing a stator core in the case or a configuration when the stator core is disposed in the case (relationship between the case and the stator core).

  In the EPS motor described in Patent Document 5, since the protrusion is in surface contact with the case, the effect of preventing deterioration of magnetic characteristics is small, and the protrusion is not necessary as a magnetic path. Since it is a part, the outer diameter and mass of the motor become large, and it is difficult to achieve miniaturization.

  The present invention has been made in view of such circumstances, and even when a stator core is press-fitted into a case, the magnetic characteristics of the stator core can be prevented from being lowered due to the press-fitting, and a brushless capable of reducing loss torque. An object is to provide a motor.

  In order to achieve this object, the present invention is a brushless motor comprising a stator having a stator core and a coil wound around the stator core, and a case housing the stator, and the stator is press-fitted into the case. The stator core has a configuration in which a plurality of electromagnetic steel plates having different outer diameters are stacked, and provides a brushless motor in which the case and the stator core are press-fitted and joined.

  In the brushless motor having this configuration, since the stator core having a configuration in which a plurality of electromagnetic steel plates having different outer diameters are stacked is press-fitted to the case, the contact area between the stator core and the case can be reduced. . Therefore, even if the stator is press-fitted into the case, deformation of the stator core due to the press-fitting can be suppressed, and the magnetic flux can be stabilized. For this reason, it can prevent that the magnetic characteristic of the said stator core falls.

  Further, the brushless motor according to the present invention is laminated such that the outer diameters of the plurality of electromagnetic steel plates are sequentially increased, and the outer peripheral surface of each of the electromagnetic steel plates and the inner periphery of the case facing the outer peripheral surface. It is possible to have a configuration in which the inner peripheral surface of the case is inclined so that each press-fitting allowance formed between the surfaces is uniform in the axial direction. By comprising in this way, since the outer peripheral surface of each electromagnetic steel plate and the inner peripheral surface of a case will carry out line contact (contact by the line along a circumference), the contact area of a stator core and a case is further increased. Can be small.

  In the brushless motor according to the present invention, a notch is formed in the outer peripheral surface of the stator core, and the control is performed between the outer peripheral surface of the stator core and the inner peripheral surface of the case via the notch. The vibration member can be filled. By configuring in this way, vibration generated when the brushless motor is driven can be absorbed by the damping member, so that generation of vibration can be suppressed in addition to the above-described advantages.

  In the brushless motor according to the present invention, the stator core may have a configuration obtained by rolling the at least one electromagnetic steel plate. By rolling the magnetic steel sheet in this way, in addition to the above-mentioned advantages, magnetic flux variation can be efficiently suppressed, so that the magnetic characteristics in the rotational direction can be improved and the loss torque can be further reduced. it can.

  Furthermore, the brushless motor according to the present invention may have a configuration in which a protrusion that can contact an end surface opposite to the press-fitting direction of the stator core is formed on the inner peripheral surface of the case into which the stator core is press-fitted. it can. By configuring in this way, in addition to the above-mentioned advantages, when the stator core tries to move to the opposite side of the press-fitting direction of the stator core, the end face of the stator core comes into contact with the protruding portion, thereby preventing the stator core from coming out. be able to.

  ADVANTAGE OF THE INVENTION According to this invention, even if it press-fits a stator core in a case, the fall of the magnetic characteristic of the stator core by the said press-fit can be prevented, and the brushless motor which can reduce loss torque can be provided.

It is a longitudinal cross-sectional view of the brushless motor which concerns on the Example of this invention. It is a top view of the stator core which is a component of the brushless motor shown in FIG. It is sectional drawing along the axial direction which simplifies and shows the state which press-fitted the stator core shown in FIG. 2 in the case which is a component of the brushless motor shown in FIG. It is sectional drawing along the IV-IV line shown in FIG. It is sectional drawing along the VV line shown in FIG.

  Next, embodiments for carrying out the present invention will be described with reference to the drawings. In addition, the Example described below is the illustration for demonstrating this invention, and this invention is not limited only to these Examples. Therefore, the present invention can be implemented in various forms without departing from the gist thereof.

  1 is a longitudinal sectional view of a brushless motor according to an embodiment of the present invention, FIG. 2 is a plan view of a stator core that is a component of the brushless motor shown in FIG. 1, and FIG. 3 is a configuration of the brushless motor shown in FIG. 2 is a simplified cross-sectional view along the axial direction showing the state in which the stator core shown in FIG. 2 is press-fitted into the element case, FIG. 4 is a cross-sectional view taken along the line IV-IV shown in FIG. 3, and FIG. 5 is a sectional view taken along line VV shown in FIG. In addition, in each said figure, in order to make explanation easy to understand, the thickness, size, enlargement / reduction ratio, etc. of each member were described without matching with an actual thing.

  As shown in FIGS. 1 to 5, a brushless motor 1 according to this embodiment includes a case 2 </ b> A formed of a magnetic material, and a substantially disc-shaped front bracket 2 </ b> B that closes one opening end of the case 2 </ b> A. have. A bottom 2a is formed integrally with the case 2A at the end of the case 2A opposite to the side on which the front bracket 2B is provided so as to close the end.

  The case 2A has a substantially conical shape (taper shape) in which the diameter on the side where the front bracket 2B is provided is gradually larger than the diameter on the bottom 2a side, and the inner peripheral surface 12 of the case 2A is inclined. It is a surface. As the magnetic material forming the case 2A, for example, a general steel material such as SPCC (Steel Plate Cold Commercial), electromagnetic soft iron, or the like can be applied. The front bracket 2B serves as a flange when the brushless motor 1 is attached to a desired device.

  Further, as shown in FIG. 3, when a stator core 7 to be described in detail later is press-fitted into the case 2A on the front bracket 2B side of the case 2A, an end surface opposite to the press-fitting direction of the stator core 7 (that is, the front bracket) A protrusion 21 that can abut on the end surface on the 2B side is formed. When the stator core 7 is about to move to the front bracket 2B side, the protrusion 21 abuts against the end surface of the stator core 7, and thus the stator core 7 can be prevented from slipping out to the front bracket 2B side. In addition, this projection part 21 can be formed with tools, such as caulking and a punch, for example.

  Inside the case 2A, a bearing 3A is disposed at a substantially central portion of the front bracket 2B, and a bearing 3B is disposed at a substantially central portion of the bottom portion 2a. The bearing 3A rotatably supports one end of the rotating shaft 4 disposed inside the case 2A, and the bearing 3B supports the other end of the rotating shaft 4 rotatably.

  A rotor core 10 is disposed on the outer peripheral side of the rotary shaft 4, and a motor driving magnet 5 is fixed on the outer peripheral side of the rotor core 10. The magnet 5 is a permanent magnet having S poles and N poles alternately magnetized in the circumferential direction of the rotary shaft 4 at equal intervals, and the brushless motor 1 is freely rotatable by the rotary shaft 4, the rotor core 10 and the magnet 5. The rotor 6 is configured. The magnet 5 may have a divided shape (segment structure) or a ring shape. Reference numeral 11 denotes a magnet cover.

  Further, the end of the rotating shaft 4 on the front bracket 2B side protrudes to the outside, and a joint 19 is provided at the end protruding to the outside. By connecting a desired shaft or the like to the joint 19, the rotational output of the brushless motor 1 can be taken out. A resolver 25 that detects the rotational position of the rotor 6 and a terminal block 26 that supports the resolver 25 are provided on the front bracket 2 </ b> B side of the rotating shaft 4. The resolver 25 includes a resolver rotor 31 fixed to the circumferential surface of the rotary shaft 4 and a resolver stator 32 disposed to face the resolver rotor 31 with a predetermined gap.

  A stator 9 is disposed between the outer peripheral side of the rotor 6 and the inner peripheral surface 12 of the case 2A. The stator 9 includes a stator core 7 and three-phase exciting coils 8 (see FIG. 1) wound around teeth 18A to 18L, which will be described in detail after the stator core 7.

  The stator core 7 has a configuration in which a plurality of magnetic steel plates (silicon steel plates) 71 to 75 having different outer diameters (in this embodiment, described as five sheets for easy understanding) are sequentially laminated. I have. Moreover, as for these electromagnetic steel plates 71-75, at least 1 electromagnetic steel plate is rolled at a predetermined angle. Thus, by rolling at least one of the electromagnetic steel sheets 71 to 75, the thickness error generated when the electromagnetic steel sheets 71 to 75 are laminated can be minimized. For this reason, variation in magnetic flux can be efficiently suppressed, magnetic characteristics in the rotational direction can be improved, and loss torque can be reduced.

  These electromagnetic steel plates 71 to 75 include an annular back yoke portion 17 constituting an outer peripheral portion, and a plurality of (in this embodiment, 12 pieces) protruding from the back yoke portion 17 toward the radial center of the back yoke portion 17. ) Teeth 18A to 18L. The electromagnetic steel sheets 71 to 75 are configured such that the outer diameter of the electromagnetic steel sheet 71 is the smallest (shorter), the outer diameter becomes larger (longer) in the stacking order, and the outer diameter of the electromagnetic steel sheet 75 is the largest. And the outer diameter of the electromagnetic steel sheets 71-75 is set so that the difference of the outer diameter of the mutually adjacent electromagnetic steel sheets may become the same. In the present embodiment, the outer diameters of the electromagnetic steel plates 71 to 75 are determined by changing the radial length of the back yoke portion 17.

  As shown in FIG. 3, the stator core 7 on which the electromagnetic steel sheets 71 to 75 are laminated is press-fitted into the case 2 </ b> A so that the electromagnetic steel sheet 71 is positioned on the bottom 2 a side of the case 2 </ b> A. Outer peripheral end 71e, an outer peripheral end 72e on the bottom 2a side of the electromagnetic steel plate 72, an outer peripheral end 73e on the bottom 2a side of the electromagnetic steel plate 73, an outer peripheral end 74e on the bottom 2a side of the electromagnetic steel plate 74, and a bottom of the electromagnetic steel plate 75. The outer peripheral end 75e on the 2a side is press-fitted and joined to the case 2A in a state where the inner peripheral surface 12 of the case 2A is in contact (line contact). Therefore, since the contact area between the stator core 7 and the case 2A can be reduced, even if the stator core 7 is press-fitted into the case 2A, deformation of the stator core 7 due to press-fitting can be suppressed, and the magnetic flux can be stabilized. It becomes. As a result, it is possible to prevent the magnetic characteristics of the stator core 7 from being lowered, and it is possible to reduce the loss torque.

  Here, since each of the electromagnetic steel sheets 71 to 75 has a constant outer diameter and the inner peripheral surface 12 of the case 2A is inclined, each of the inner peripheral surface 12 of the case 2A and each of the electromagnetic steel sheets 71 to 75 is included. In particular, as shown in FIG. 3, press-fitting allowances (gap) 81 to 85 are respectively formed between the outer peripheral surfaces of the two. In the present embodiment, the inner peripheral surface 12 of the case 2A is inclined so that these press-fitting allowances 81 to 85 are uniform in the axial direction. Each of the laminated electromagnetic steel sheets 71 to 75 is concentric with the inner peripheral surface 12 of the case 2A. Therefore, the stator core 7 is also concentric with the inner peripheral surface 12 of the case 2A.

  Further, notches for filling the press-fitting allowances 81 to 85 with the damping members 90 at the respective positions (that is, the respective positions at both ends in the radial direction) of the outer peripheral surfaces of the electromagnetic steel sheets 71 to 75 facing each other. 91 to 95 are formed. These notches 91 to 95 are formed so as to communicate with each other when the electromagnetic steel sheets 71 to 75 are laminated, and the notches 91 do not penetrate to the bottom 2a side in the laminating direction. Terminated with. With this configuration, the damping member 90 injected from the notch 95 is sequentially supplied to the notches 94, 93, 92, 91 and filled into the press-fitting allowances 81 to 85. As described above, by filling the press-fitting allowances 81 to 85 with the vibration damping member 90, the vibration generated when the brushless motor 1 is driven can be absorbed by the vibration damping member 90, and the generation of vibration can be suppressed. it can. In addition, as the damping member 90, adhesive elastic resin, rubber | gum, etc. are mentioned, for example.

  The stator 9 has a configuration in which four coil groups each including a three-phase excitation coil are continuously arranged. Specifically, the stator core 7 is formed by, for example, exciting coils 8 wound around the teeth 18A, 18B, and 18C (exciting coils are not shown in FIGS. 2 to 5 for easy understanding). One coil group (first coil group) is formed, and another coil group (second coil group) is formed by the excitation coil 8 wound around each of the teeth 18D, 18E, and 18F. Another exciting coil group (third coil group) is formed by the exciting coil 8 wound around each of the teeth 18G, 18H, and 18I, and the exciting coil 8 wound around each of the teeth 18J, 18K, and 18L. The other coil group (fourth coil group) is formed. Reference numeral 28 denotes an insulator.

  In addition, in this embodiment, in order to make an explanation easy to understand, the case where five electromagnetic steel plates 71 to 75 are laminated as the configuration of the stator core 7 has been described. However, the configuration is not limited thereto, and the stator core 7 includes six or more stator cores 7. The structure which laminated | stacked the electromagnetic steel plate from which each outer diameter differs may be sufficient. Alternatively, a plurality of block bodies in which a plurality of electromagnetic steel plates having the same outer diameter are laminated may be prepared so that the outer diameters of the respective block bodies are different. In the case of this configuration, the electromagnetic steel sheet constituting the block body may be rolled up, or the block body may be rolled up.

  Moreover, although this embodiment demonstrated the case where the notches 91-95 were formed in two places (on the same diameter) which mutually oppose, not only this but the notches 91-95 are the electromagnetic steel plates 71 depending on necessity. 1 to 75 each may be formed, or 3 or more may be formed.

  DESCRIPTION OF SYMBOLS 1 ... Brushless motor, 2A ... Case, 4 ... Rotating shaft, 7 ... Stator core, 8 ... Excitation coil, 9 ... Stator, 12 ... Inner peripheral surface, 17 ... Back yoke part, 18A-18L ... Teeth, 21 ... Projection part, 71-75 ... Electromagnetic steel plate (silicon steel plate), 81-85 ... Press-fit allowance, 90 ... Damping member, 91-95 ... Notch

Claims (4)

A stator core and a stator having a coil wound around the stator core; and a case for housing the stator; and a brushless motor in which the stator is press-fitted into the case,
The stator core has a configuration in which a plurality of electromagnetic steel sheets having different outer diameters are laminated,
The case and the stator core are press-fitted and coupled ,
The plurality of electrical steel sheets are laminated so that the outer diameter sequentially increases,
The case is formed so that each press-fitting allowance formed between the outer peripheral surface of each electromagnetic steel sheet and the inner peripheral surface of the case facing the outer peripheral surface is uniform in the axial direction. Brushless motor with an inner peripheral surface inclined . Forming a notch on the outer peripheral surface of the stator core, through the notch, and the outer peripheral surface of the stator core, formed by filling a damping member between the inner peripheral surface of the casing according to claim 1, wherein Brushless motor. The brushless motor according to claim 1, wherein the stator core is formed by rolling the at least one electromagnetic steel sheet. The inner peripheral surface of the case in which the stator core is press-fitted, according to any one of claims 1 to 3 capable of abutting projections on the end face of the press-fitting direction opposite of the stator core is formed Brushless motor.

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