JP2006304494A - Brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-cogging brushless motor mounted to a portable personal computer. <P>SOLUTION: In the brushless motor with a rotor magnet 6 and a stator 4 comprising a stator core having a plurality of salient poles and a stator coil 3, cogging torque is reduced, teeth 1 (tips of the salient poles) of the stator 4 are reinforced, and resonant oscillation generated from the teeth is reduced by mounting at least one layer of a ring member 7 comprising a magnetic material on the outer circumference of the end face of the stator 4 in the axial direction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a brushless motor used for rotationally driving an optical disk such as a digital video disk (DVD) recently installed in a portable personal computer.

  Recently, an optical disk drive device or a hard disk drive mounted on a portable personal computer or the like has a rotor magnet mounted on the inner surface of the rotor, a stacked stator core disposed opposite to the inner periphery of the rotor magnet, and a plurality of phases. A so-called coreless brushless motor having a stator having a stator coil is generally used. Brushless motors mounted on the above devices are required to be thinner, smaller, and lighter, and to reduce cogging torque, that is, vibration and noise during operation.

  However, the brushless motor with a core has a structural problem in that cogging torque is generated by a gap between adjacent core teeth. As a brushless motor that seeks to reduce the cogging torque, a configuration in which the gap between the teeth is connected with a magnetic material has been proposed. As an example, FIG. 5 shows a configuration in which the teeth of the salient poles of each core formed in a divided manner are connected by a thin portion, the stator coil is wound, and then molded into an annular shape to complete a stator assembly.

  In FIG. 5, the brushless motor has a connecting portion 2 between teeth 1, a stator 4 portion provided with a stator coil 3, and a rotor magnet 6 on the inner periphery of the rotor 5 (for example, Patent Document 1). reference).

In addition to the conventional brushless motor, there is a configuration in which a reduction in cogging torque is required in a so-called inner rotor type brushless motor in which a rotor is disposed inside a stator. It is configured to simultaneously reduce the cogging torque by connecting the teeth at the connecting portion formed thinner than the thickness of the stator core and to suppress the reduction in efficiency due to a short circuit of the magnetic flux at the connecting portion (for example, a patent) Reference 2).
JP 2000-209795 (page 4, FIG. 1) JP 2003-88007 A (Page 6, FIG. 2)

  However, in the first conventional configuration, there is a problem that the magnetic loss increases due to the strain after the core coupling and the processing strain caused by the thinning of the core. Further, in the configuration of the second conventional technique, there is a problem that the winding method of the stator coil needs to take a special method, and the number of man-hours increases.

  The present invention solves such a conventional problem, and an object of the present invention is to provide a brushless motor that can reduce vibration and noise during operation with high efficiency and low cost.

  In order to solve the above-described problems, the present invention has a rotor magnet mounted on an inner surface of a rotor and a rotating shaft fixed to the rotor, and is laminated so as to face the inner periphery of the rotor magnet. In a brushless motor having a stator having a stator core having a plurality of salient poles and a stator coil having a plurality of phases, at least one layer of a ring-shaped member made of a magnetic material is mounted on the outer peripheral side of the axial end surface of the stator. It is.

  According to the first aspect of the present invention, by attaching a ring-shaped member made of at least one layer of magnetic material to the stator, not only the cogging torque is reduced, but also the teeth portion (saliency pole) having the smallest rigidity in the stator. Since the front end portion can be reinforced, an advantageous effect that resonance vibration generated by the tooth portion can be reduced can be obtained.

  Moreover, according to invention of Claim 2, 3 and 4, the leakage of the magnetic flux in the joint part of teeth can be suppressed, and the fall of an output can be suppressed. Further, since the ring-shaped member is formed independently of the stator core, it is possible to select an arbitrary shape and material, and it is easy to set an optimum configuration. Further, since the ring-shaped member can be attached after the stator coil is wound around the stator, an effect that the motor assembling method can be simplified can be obtained.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

(Embodiment 1)
1A and 1B are sectional views of a brushless motor according to the first embodiment of the present application. In FIGS. 1A and 1B, reference numeral 4 denotes a stator formed by winding a stator coil 3 around each salient pole of a laminated stator core, and reference numeral 5 denotes an outer periphery of the stator 4. This is a rotor in which the ring-shaped rotor magnet 6 is fixed to the inner periphery. A ring-shaped member 7 made of a magnetic material is mounted on the outer peripheral side of the axial end surface of the stator 4 to magnetically connect the teeth 1 of the stator core. The ring-shaped member 7 is fixed to the stator 4 by welding or adhesion. Since the ring-shaped member 7 is later attached and coupled to the stator 4 to which the stator coil 3 is applied, the winding method can be the same as the conventional method.

  Since the stator 4 formed in this way is magnetically coupled between the teeth 1 on the outer peripheral side by the ring-shaped member 7, the cogging torque is small, and the thickness of the combined ring-shaped member 7 is reduced to the starter core. Therefore, the loss can be suppressed because the eddy current flowing between the teeth 1 can be reduced. Further, by reinforcing each part of the teeth with the ring-shaped member 7, the rigidity is increased, and the resonance vibration caused by the one part of the teeth of the stator 4 can be reduced.

  In the above embodiment, the ring-shaped member 7 is attached only to one end face side of the stator 4, but a similar ring-shaped member 7 may be attached to the opposite end face. As described above, when the equivalent ring-shaped members 7 are attached to both axial end surfaces of the stator 4, the magnetic balance in the vertical direction with respect to the axial center of the stator 4 is balanced. As a result, it is possible to suppress the occurrence of axial vibration.

(Embodiment 2)
FIG. 2 is a perspective view of a ring-shaped member according to the second embodiment of the present application. By adopting a structure in which a thin portion with respect to the thickness direction is formed at a position corresponding to between adjacent salient poles of the stator core of the ring-shaped member 7, eddy currents flowing between the teeth 1 of the stator core can be suppressed.

(Embodiment 3)
A perspective view of a ring-shaped member according to the third embodiment of the present application is shown in FIG. By adopting a configuration in which a thin portion with respect to the circumferential direction is formed at a position corresponding to between the adjacent salient poles of the stator core of the ring-shaped member 7, eddy currents flowing between the teeth 1 of the stator core can be suppressed.

(Embodiment 4)
A perspective view of a ring-shaped member according to the fourth embodiment of the present application is shown in FIG. By adopting a configuration in which thin portions in the thickness direction and the radial direction are formed at positions corresponding to adjacent salient poles of the stator core of the ring-shaped member 7, eddy currents flowing between the teeth 1 of the stator core can be suppressed. it can.

  The brushless motor of the present invention has the effects of low cogging and low vibration, and is useful as a brushless motor used for rotationally driving an optical disk or a hard disk mounted on a portable personal computer or the like.

(A) Plan sectional drawing which shows the brushless motor by Example 1 of this invention, (b) Structural sectional drawing which shows the brushless motor by Example 1 of this invention The perspective view of the ring-shaped magnetic member by Example 2 of this invention The perspective view of the ring-shaped magnetic member by Example 3 of this invention The perspective view of the ring-shaped magnetic member by Example 4 of this invention Plan sectional view showing a conventional brushless motor

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Teeth 2 Connection part 3 Stator coil 4 Stator 5 Rotor 6 Rotor magnet 7 Ring-shaped member

Claims (4)

A rotor core mounted on the inner surface of the rotor, a rotating shaft fixed to the rotor, a stator core having a plurality of stacked salient poles arranged opposite to the inner periphery of the rotor magnet, and a plurality of phases A brushless motor comprising a stator having a stator coil, wherein the ring-shaped member made of a magnetic material is mounted on the outer peripheral side of the axial end surface of the stator. 2. The brushless motor according to claim 1, wherein the ring-shaped member has a thin portion formed in a position corresponding to between adjacent salient poles of the stator core in the thickness direction. 2. The brushless motor according to claim 1, wherein the ring-shaped member has a thin portion formed in a radial direction at a position corresponding to between adjacent salient poles of the stator core. 2. The brushless motor according to claim 1, wherein the ring-shaped member is formed with a thin portion at a position corresponding to between the salient poles adjacent to each other in the thickness direction and the radial direction.

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