JP2005204380A - Axial gap type motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an axial gap type motor which can effectively suppress rotation deviation generated at the time of the rotation of a rotor. <P>SOLUTION: In the axial gap type motor, the gap G formed between the magnetized surface 241 of a stator 2 and the magnetized surfaces 331 of rotors 31, 32 is formed by inclining at a predetermined angle with respect to the axial direction of a rotor output shaft 3. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an axial gap type electric motor in which a stator and a rotor are arranged to face each other with a predetermined gap (gap) along an axial direction of an output shaft, and more specifically, rotational runout (blur) generated when the rotor rotates. The present invention relates to an axial gap type electric motor that suppresses noise.

  An axial gap type electric motor is an electric motor in which a disk-shaped rotor is arranged oppositely with a predetermined gap (gap) with respect to the axial direction of a disk-shaped stator. Can be designed to be thin, it is preferably used as a drive motor such as a hub motor or FD drive of a bicycle with an electric motor.

  As an example, there is Patent Document 1, for example. In this axial gap type electric motor, by arranging the first and second magnets in parallel so as to sandwich both sides of the stator stator, the magnetic flux can be captured effectively and high torque can be obtained. .

  In general, in an axial gap type electric motor, it is important that the gap (gap) formed between the magnetic pole surface of the stator and the magnetic pole surface of the rotor is uniform. This is because the distance between the surfaces of the gap is made small in order to increase the output of the motor as much as possible. If the distance between the surfaces of the gap is not uniform, the rotor may come into contact with the stator.

  However, as shown in FIG. 5, in the case where the gap is formed in a vertical plane (perpendicular to the axial direction of the output shaft), all the magnetic attractive force F generated when the motor is energized is directed to the stator side. The magnetic attraction force F was increased, and rotational vibration (blur) was likely to occur due to the attraction repulsive force generated when the magnet of the rotor climbed over each tooth (stator) of the stator. If the rotational runout increases, the stator and the rotor come into contact with each other, which may cause abnormal noise or cause a motor failure.

JP 2000-253635 A

  Therefore, an object of the present invention is to provide an axial gap type electric motor that can effectively suppress rotational runout that occurs during rotation of a rotor.

  In order to solve the above-described problems, the present invention provides an axial gap motor according to claim 1, wherein the stator and the rotor are arranged to face each other so that a parallel gap is formed between their magnetic pole faces. The magnetic pole surfaces of the rotor and the stator are inclined at a predetermined angle with respect to the axial direction of the output shaft.

  In claim 2, the inclined surface is a straight surface, and in claim 3, the inclined surface is a curved surface.

  According to a fourth aspect of the present invention, the inclined surface has a convex surface on the stator side, and accordingly, the rotor side has a concave surface.

  According to a fifth aspect of the present invention, each of the magnetic pole surfaces has a concave surface on the stator side, and accordingly, the rotor side has a convex surface.

  According to the first aspect of the present invention, since the magnetic pole surfaces of the rotor and the stator are inclined at a predetermined angle with respect to the axial direction of the output shaft, the magnetic attraction in the normal direction generated when a voltage is applied. Since the force is reduced by vector decomposition, it is possible to effectively suppress rotational shake.

  According to invention of Claim 2 or 3, a moldability is good by making an inclined surface into a linear surface. Further, by using the curved surface, the vector-resolved magnetic attraction force is decomposed along the tangential direction of the curve, so that the rotational shake can be more effectively suppressed.

  According to invention of Claim 3 or 4, since the rotor side is a concave surface, the weight of a rotor can be reduced and a rotation shake can be suppressed further.

  Next, an embodiment of an axial gap type electric motor of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing an internal structure of an axial gap type electric motor according to an embodiment of the present invention.

  This axial gap type electric motor 1 includes a stator 2 formed in a disk shape, and a pair of rotors 31 and 32 disposed opposite to each other with a predetermined gap (gap) G on both sides of the stator 2. In this embodiment, the axial gap type electric motor 1 is a permanent magnet type electric motor.

  In addition, although this axial gap type electric motor 1 has arrange | positioned a pair of rotors 31 and 32 on the both sides of the stator 2, only any one may be sufficient. Further, each mechanism including the stator 2 and the rotors 31 and 32 is actually housed in a bracket (not shown). However, in the present invention, the configuration of the bracket is arbitrary and is not shown, and the description thereof is omitted.

  The stator 2 includes a stator core 21 formed in an annular shape and a bearing portion 22 disposed at the center of the stator core 21 as a bearing portion of the rotor output shaft 3, which are integrally molded with a synthetic resin 23. . Each rotor 31 and 32 is coaxially fixed with respect to the rotor output shaft 3 which outputs a rotational driving force.

  A plurality of fan-shaped teeth 24 having a narrow outer peripheral width and a wide inner peripheral width are annularly arranged in the stator core 21 along the circumferential direction. A coil (stator winding) 25 is wound around each tooth 24 using this as a bobbin. The coil 25 wound around each tooth 24 is connected to a drive circuit (not shown) and generates a magnetic force when supplied with a drive current.

  As shown in FIG. 1, the teeth 24 are formed by stacking a plurality of punched magnetic steel sheets of different sizes in a direction orthogonal to the axial direction of the output shaft 3 to form one block body. Thus, both end surfaces in the axial direction (left and right in FIG. 1), so-called magnetic pole surfaces 241 and 241 are formed in a trapezoidal cross-section that is inclined at a predetermined angle.

  In this example, the magnetic pole surfaces 241 and 241 are inclined surfaces that are inclined toward the outer peripheral direction of the stator 2. In this embodiment, the inclined surfaces 241 and 241 are inclined so as to have an inclination angle of 45 °. . The more preferable inclination angle of the inclined surfaces 241 and 241 is preferably set within a range of 35 to 50 °.

  According to this, as shown in FIG. 2, an annular inclined surface formed by connecting the teeth 24 to both end surfaces of the stator 2 appears.

  The bearing portion 22 has two radial ball bearings 221 and 222 and is provided coaxially in the center of the stator 2. The output shaft 3 is press-fitted and fixed to the inner diameter rings of the radial ball bearings 221 and 222. In the present invention, the configuration of the bearing portion 22 is arbitrary.

  Next, the rotors 31 and 32 will be described. In addition, since each rotor 31 and 32 is symmetrical shape on both sides of the stator 2, in this embodiment, one rotor 31 is demonstrated and description about the other rotor 32 is abbreviate | omitted.

  The rotor 31 includes a disk-shaped rotor main body (hub) 34 fixed to the rotor output shaft 3 and a rotor magnet 33 supported by the rotor main body 34. The rotor magnet 33 includes a plurality of magnet chips formed in a fan shape (not shown) for each magnetic pole, and is integrally incorporated in the rotor body 34.

  As shown in FIG. 1, the rotor magnet 33 forms a gap G parallel to the magnetic pole surface 241 of the opposing stator core 24. Therefore, a magnetic pole surface 331 parallel to the magnetic pole surface 241 of the stator core 24 is formed on the opposing surface side. I have.

  According to this, as shown in FIG. 3, since the gap G is formed in a state inclined at a predetermined angle with respect to the axial direction of the rotating shaft, the magnetic attractive force F generated in the rotor is perpendicular to the axial direction. By vector decomposition into a working force Fa and a force Fb working in a direction parallel to the axial direction, the magnetic attraction force is weakened, so that the rotational shake due to rotation can be effectively suppressed. Moreover, since it is not inclined in the rotational direction, the rotational component of F does not change, and the torque and rotational efficiency can be kept constant.

  Furthermore, by making each magnetic pole surface a parallel inclined surface, the gap area is increased as compared with the case where the gap surface is a vertical plane, and thus torque and rotational efficiency are improved.

  In this embodiment, the inclined surface 241 of the stator core 24 and the inclined surface 331 of the rotor magnet 33 are linear in consideration of ease of molding, and the gap G is also provided on the straight line accordingly. However, for example, as shown in FIG. 4a, the inclined surfaces 241a and 331a may have a curved shape with a predetermined curvature. Such an embodiment is also included in the present invention.

  According to this, by making each inclined surface 241a, 331a into a curved surface, the vector-resolved magnetic attraction force is decomposed along the tangential direction of the curve, so that the rotational shake can be more effectively suppressed. .

  Furthermore, each inclined surface 331.241 of the present invention is formed so as to be inclined toward the outer circumferential direction. In addition to this, as shown in FIG. 4b, each inclined surface of the stator core 24b and the rotor magnet 33b. You may make it incline 241b, 331b toward an axial direction.

  An example of the assembly procedure of the axial gap type electric motor 1 will be described. First, the tip of the rotor output shaft 3 previously attached to one rotor 31 is inserted into the bearing portion 22 of the stator 2 so that the stator 22 and the rotor 31 are predetermined. Is press-fitted and fixed so as to form a gap surface maintaining the distance between the surfaces.

  Next, the other rotor 32 is inserted from the tip of the rotor output shaft 3, and the stator 22 and the rotor 32 are press-fitted and fixed so as to form a gap surface maintaining a predetermined inter-surface distance. Finally, the outer peripheral end of the stator is fixed with a bracket (not shown) to complete the axial gap type electric motor 1.

  In the present invention, the stator core 24 is convex and the rotor magnet 33 is concave, but conversely, the stator core 24 side may be concave and the rotor magnet 33 may be convex.

  In this embodiment, the axial gap type electric motor 1 is a permanent magnet type electric motor using a rotor magnet 33 made of a permanent magnet for the rotor 3, but the present invention may be applied to an induction type electric motor. If the gap G formed between the stator 2 and the rotors 31 and 32 is inclined at a predetermined angle with respect to the axial direction, this type of modification is also included in the present invention.

1 is a cross-sectional view schematically showing an internal structure of an axial gap type electric motor according to an embodiment of the present invention. The perspective view of the stator of the axial gap type electric motor of the said embodiment. Explanatory drawing explaining the effect of the axial gap type electric motor of this invention. The schematic diagram which shows the modification of the axial gap type electric motor of this invention. The schematic diagram which shows the modification of the axial gap type electric motor of this invention. Explanatory drawing explaining the effect of the conventional axial gap type motor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Axial gap type electric motor 2 Stator 21 Stator core 22 Bearing part 23 Synthetic resin 24 Teeth 241 Inclined surface 25 Coil 31, 32 Rotor 33 Rotor magnet 331 Inclined surface G Gap

Claims (3)

In the axial gap type electric motor in which the stator and the rotor are arranged to face each other so that a gap is formed between their magnetic pole faces,
Each axial surface of the rotor and the stator is inclined at a predetermined angle with respect to the axial direction of the output shaft.   The axial gap type electric motor according to claim 1, wherein each of the magnetic pole surfaces is a straight surface and / or a curved surface.   3. The axial gap type electric motor according to claim 1, wherein each of the magnetic pole surfaces has a convex surface or a concave surface on the stator side, and accordingly, the rotor side has a concave surface or a convex surface.

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