JP2007014178A - Rotor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotor which improves response of a motor irrespective of a position of a magnetic polarity. <P>SOLUTION: The rotor 10 includes a rotating shaft 11, a rotor back yoke 12 fixed so that it may integrally rotate around the rotating shaft, and a permanent magnet 13 which is stuck to the outer peripheral face of the rotor back yoke. The rotor back yoke 12 includes a hollow portion 12b in an axial intermediate portion, at such a portion as excluding an outer periphery 12c in contact with the permanent magnet 13. A magnetic path width W1 of the outer periphery 12c is constituted to have a dimension which does not cause saturation of magnetic flux. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a rotor provided in a motor.

  Conventionally, for example, a brushless motor has a winding on the stator (stator) side and a permanent magnet on the rotor (rotor) side. And as a rotor, what equipped the rotor back yoke between the rotating shaft (shaft) and a permanent magnet is also known (for example, patent document 1 etc.). The rotor back yoke has both a function for fixing the rotating shaft and the permanent magnet so as to rotate integrally, and a function as a magnetic path for efficiently passing the magnetic flux of the permanent magnet.

4 (a), 4 (b) and 5 (a), 5 (b) are a plan view and a longitudinal sectional view showing a conventional form of such a rotor. As shown in the figure, the rotor 90 includes a rotating shaft 91, a rotor back yoke 92 fixed so as to rotate integrally with the rotating shaft 91, and a permanent magnet 93 fixed to the outer peripheral surface of the rotor back yoke 92. And. 4 shows a rotor back yoke 92A formed by molding (sintering) magnetic powder, and FIG. 5 shows a rotor back yoke 92B formed by stacking steel plates.
Japanese Patent Laid-Open No. 9-275669 JP-A-9-275552

  By the way, any rotor back yoke 92A, 92B shown in FIG. 4 and FIG. 5 becomes a lump of magnetic material that fills the entire space between the rotary shaft 91 and the permanent magnet 93. Moment) will increase and the motor response will be impaired.

  On the other hand, in the technique of Patent Document 2, a space is provided on the extension of the center of the magnet divided into a plurality of arcs in cross section. In this case, if an attempt is made to create a magnet by magnetizing the magnetic body after providing an undivided ring-shaped magnetic body on the outer periphery of the rotor back yoke, it is necessary to accurately position the magnetized. . Furthermore, if skew magnetization is performed such that the magnetic poles are shifted in the circumferential direction as they go in the axial direction, the space must be provided in a spiral shape.

  Therefore, an object of the present invention is to improve the responsiveness of the motor regardless of the position of the polarity of the magnet.

  In order to solve the above problems, the invention according to claim 1 is fixed to a rotating shaft, a rotor back yoke fixed to rotate integrally with the rotating shaft, and an outer peripheral surface of the rotor back yoke. In a rotor including a permanent magnet, the rotor back yoke has a thinned portion in a portion excluding the outer peripheral portion in contact with the permanent magnet, and the magnetic path width of the outer peripheral portion is set to a size that does not cause saturation of magnetic flux. Is the gist.

  According to a second aspect of the present invention, in the rotor according to the first aspect, the thinned portions are recessed radially outward from the inner peripheral surface at both axial end portions of the rotor back yoke. The gist.

  According to a third aspect of the present invention, in the rotor according to the first aspect, the thinned portion is formed to be recessed radially outward from the inner peripheral surface at an axially intermediate portion of the rotor back yoke. The gist.

  According to a fourth aspect of the present invention, there is provided a rotor including a rotating shaft, a rotor back yoke fixed so as to rotate integrally with the rotating shaft, and a permanent magnet fixed to an outer peripheral surface of the rotor back yoke. The rotor back yoke includes a plurality of holes that are parallel to the axial direction of the rotating shaft and provided at predetermined angles in the circumferential direction, and the holes are arranged at the same distance from the rotating shaft, respectively. Magnetic path width between the inner peripheral surface of the yoke and the inner peripheral surface of each hole, magnetic path width between the inner peripheral surface of each hole and the outer peripheral surface of the rotor back yoke, and between each hole and the hole The gist of the magnetic path width is to set the magnetic path width so as not to cause saturation of the magnetic flux.

  According to a fifth aspect of the present invention, in the rotor according to the fourth aspect, the inner circumferential surface of the rotor back yoke has a plurality of notches for reducing a press-fit load when fixed to the rotating shaft. The gist is that the holes are formed at predetermined angles in parallel to the direction, and the plurality of holes are arranged at an angular position of a central portion of each adjacent notch.

  According to a sixth aspect of the present invention, in the rotor according to the fifth aspect, the magnetic path width between the tip of the notch and the inner peripheral surface of the hole is secured so that no magnetic flux saturation occurs. The gist is to set so that.

(Function)
According to the first or second aspect of the present invention, the rotor back yoke has a lightening portion in a portion excluding the outer peripheral portion that is in contact with the permanent magnet. Inertia (moment of inertia) is reduced, and the responsiveness of the motor including the rotor is improved. In addition, the magnetic path width of the outer peripheral portion is set to a dimension that does not cause saturation of the magnetic flux. For example, after providing a ring-shaped magnetic body that is not divided on the outer periphery of the rotor back yoke, the magnetic body is magnetized. Even in the case of taking a method of creating a magnet, it is not necessary to accurately position the magnetizing.

  According to the third aspect of the present invention, the lightening portion is recessed radially outward from the inner peripheral surface at the axially intermediate portion of the rotor back yoke. At both ends in the axial direction, both ends are fixed to the rotating shaft. Therefore, the rotor back yoke is fixed and supported on the rotating shaft in a more stable posture.

  According to a fourth aspect of the present invention, the rotor back yoke is parallel to the axial direction of the rotating shaft and includes a plurality of holes provided at predetermined angles in the circumferential direction. The inertia of the rotor is reduced by the corresponding weight reduction, and the responsiveness of the motor including the rotor is improved. Further, the plurality of holes are arranged at the same distance from the rotation axis, and the magnetic path width (W4) between the inner peripheral surface of the rotor back yoke and the inner peripheral surface of each hole, and the inner peripheral surface of each hole Magnetic path width (W5) between each of the rotor back yoke and the outer peripheral surface of the rotor back yoke, and magnetic path width (W6) between each hole so as to ensure a magnetic path width that does not cause saturation of the magnetic flux. Even if the magnet is made by magnetizing the magnetic body after providing a ring-shaped magnetic body that is not divided, for example, on the outer periphery of the rotor back yoke, the magnetizing positioning can be achieved. There is no need to do it exactly. In particular, since the magnetic path is formed on both sides in the radial direction of the rotor back yoke even at the angular position where the plurality of holes are disposed, the plurality of holes are provided for the required magnetic path width. It can arrange | position to the outer peripheral side of a yoke, In this case, the inertia of a rotor is reduced more.

  According to the invention described in claim 5 or 6, the plurality of holes are arranged at an angular position of a central portion of each adjacent notch so that, for example, the holes and the notch have the same angle with each other. The opening area of the hole when securing a predetermined magnetic path width can be further increased as compared with the case where the rotor is disposed at a position, and in this case, the inertia of the rotor is further reduced.

  In the inventions according to claims 1 to 6, the responsiveness of the motor can be improved regardless of the position of the polarity of the magnet.

(First embodiment)
Hereinafter, a first embodiment in which the present invention is embodied in a rotor of a brushless motor will be described with reference to FIG. 1A is a plan view showing the rotor 10 of this embodiment, and FIG. 1B is a cross-sectional view taken along line 1B-1B in FIG. As shown in FIG. 1, the rotor 10 includes a rotating shaft 11, a rotor back yoke 12, and a permanent magnet 13.

  The rotor back yoke 12 is formed by laminating steel plates, and has an inner diameter equivalent to the outer diameter of the rotating shaft 11 and is formed in a substantially cylindrical shape. A plurality (ten) notches 12a are formed on the inner peripheral surface of the rotor back yoke 12 at predetermined angles in parallel with the axial direction. The rotor back yoke 12 is fixed so as to rotate integrally with the rotary shaft 11 by being press-fitted into the rotary shaft 11. At this time, the press-fit load between the rotary shaft 11 and the rotor back yoke 12 is reduced by the plurality of notches 12a.

  Further, the rotor back yoke 12 is formed with a thinned portion 12b that is concentrically recessed from the inner peripheral surface to the outer side in the radial direction at the axially intermediate portion thereof. That is, the rotor back yoke 12 has a thinned portion 12b in a portion excluding the outer peripheral portion 12c in contact with the permanent magnet 13. The thinned portion 12b is formed so that the rotor back yoke 12 has a symmetrical structure with respect to a plane orthogonal to the axial direction. The thinned portion 12b is formed by changing the shape of the steel plates laminated at both axial end portions and the intermediate portion. That is, the steel plates 14 laminated at both axial ends are formed in a disc shape having an inner diameter equivalent to the outer diameter of the rotating shaft 11. On the other hand, the steel plates 15 laminated in the intermediate portion in the axial direction are formed in a disk shape having an inner diameter larger than the outer diameter of the rotating shaft 11 and an outer diameter equivalent to the steel plate 14. The thickness of the rotor back yoke 12 (the distance in the radial direction from the outer peripheral surface of the rotating shaft 11 to the inner peripheral surface of the thinned portion 12b) is a required magnetic path in the outer peripheral portion 12c of the rotor back yoke 12. The width W1 is secured, and the dimension is set such that the magnetic flux is not saturated.

  The permanent magnet 13 is formed in a cylindrical shape having an inner diameter equivalent to the outer diameter of the rotor back yoke 12, and is fixed to the outer peripheral surface of the rotor back yoke 12. This permanent magnet 13 has a polarity (N pole, S pole) that alternates at every predetermined angle. The permanent magnet 13 may be formed by integrating a plurality of arc-shaped permanent magnets in a cylindrical shape so that the polarities are alternate, and magnetizes a single cylindrical material with alternate polarities. It may be what you did.

The rotor 10 having such a structure is rotatably accommodated inside a known stator having windings, and is driven to rotate by feeding control of the windings.
As described above in detail, according to the present embodiment, the following effects can be obtained.

  (1) In the present embodiment, the rotor back yoke 12 has the lightening portion 12b in the portion excluding the outer peripheral portion 12c in contact with the permanent magnet 13, thereby reducing the weight of the rotor 10 due to the formation thereof. Inertia can be reduced, and the responsiveness of the motor including the rotor 10 can be improved.

  In addition, since the magnetic path width W1 of the outer peripheral portion 12c is set to a size that does not cause magnetic flux saturation, for example, an undivided ring-shaped magnetic body is provided on the outer periphery of the rotor back yoke 12, and then the magnetic body is magnetized. Thus, even when the method of creating a magnet is adopted, it is not necessary to accurately position the magnetizing.

  (2) In the present embodiment, the thinned portion 12b is recessed radially outward from the inner peripheral surface in the axially intermediate portion of the rotor back yoke 12, so that the rotor back yoke 12 is Both end portions in the axial direction are fixed to the rotating shaft 11 by both-end support. Therefore, the rotor back yoke 12 can be fixed and supported on the rotary shaft 11 in a more stable posture.

(Second Embodiment)
Hereinafter, a second embodiment in which the present invention is embodied in a rotor of a brushless motor will be described with reference to FIG. Note that the second embodiment has a configuration in which thinned portions are formed at both axial end portions of the rotor back yoke, and thus detailed description of similar portions is omitted.

  Fig.2 (a) is a top view which shows the rotor 20 of this embodiment, FIG.2 (b) is sectional drawing along the 2B-2B line | wire of Fig.2 (a). As shown in the figure, the rotor back yoke 21 of the rotor 20 is formed by laminating steel plates, and has an inner diameter equivalent to the outer diameter of the rotating shaft 11 and is formed in a substantially cylindrical shape. Has been. The rotor back yoke 21 is formed with thinned portions 21a and 21b that are concentrically recessed from the inner peripheral surface to the radially outer side at both axial end portions. The hollow portions 21a and 21b are formed so that the rotor back yoke 21 has a symmetrical structure with respect to a plane orthogonal to the axial direction. These thinned portions 21a and 21b are formed by changing the shape of the steel plates laminated at both axial end portions and the intermediate portion. That is, the steel plates 22 laminated at the axially intermediate portion are formed into a disk shape having an inner diameter equivalent to the outer diameter of the rotating shaft 11. On the other hand, the steel plates 23 laminated at both ends in the axial direction are formed in a disk shape having an inner diameter larger than the outer diameter of the rotating shaft 11 and an outer diameter equivalent to the steel plate 22. Note that the thickness of the rotor back yoke 21 (the distance in the radial direction from the outer peripheral surface of the rotating shaft 11 to the inner peripheral surfaces of the thinned portions 21a and 21b) depends on the outer peripheral portion 21c of the rotor back yoke 12. The dimension is set such that the magnetic path width W2 is secured and the magnetic flux is not saturated.

As described above in detail, according to the present embodiment, the same effect as (1) in the first embodiment can be obtained.
(Third embodiment)
Hereinafter, a third embodiment in which the present invention is embodied in a rotor of a brushless motor will be described with reference to FIG. In addition, since 3rd Embodiment is the structure which employ | adopted the several hole penetrated in parallel with the axial direction of a rotor back yoke as a lightening part, the detailed description is abbreviate | omitted about the same part.

  FIG. 3A is a plan view showing the rotor 30 of the present embodiment, and FIG. 3B is a cross-sectional view taken along line 3B-3B in FIG. As shown in the figure, the rotor back yoke 31 included in the rotor 30 is formed by laminating steel plates having the same shape, and has an inner diameter equivalent to the outer diameter of the rotary shaft 11 and is substantially cylindrical. It is formed in a shape. The rotor back yoke 31 is formed with a plurality (ten) of holes 32 penetrating at predetermined angles in parallel with the axial direction. The holes 32 are arranged at the same distance from the rotating shaft 11. The plurality of holes 32 are arranged at the angular position of the central portion of each adjacent notch 12a on the outer peripheral side of the notch 12a. In other words, the plurality of notches 12 a are disposed at the angular position of the central portion of each adjacent hole 32. The opening area and the radial position of these holes 32 are set so that a required magnetic path width is substantially secured. For example, with respect to the flow of magnetic flux on the inner peripheral side of the hole 32, the magnetic path width W 3 is between the tip of each adjacent notch 12 a and the inner peripheral surface of each hole 32 and the inner surface of the rotor back yoke 31. A magnetic path width W4 is ensured between the peripheral surface (the outer peripheral surface of the rotating shaft 11) and the inner peripheral surface of each hole 32. Further, with respect to the flow of magnetic flux on the outer peripheral side of the hole 32, a magnetic path width W <b> 5 is secured between the inner peripheral surface of the hole 32 and the outer peripheral surface of the rotor back yoke 31. Further, a magnetic path width W6 is secured between the inner peripheral surfaces of the adjacent holes 32. These magnetic path widths W3 to W6 are set so as to ensure a substantial magnetic path width that does not cause saturation of magnetic flux.

As described above in detail, according to the present embodiment, the following effects can be obtained in addition to the effect (1) in the first embodiment.
(1) In the present embodiment, the rotor back yoke 31 is provided with a plurality of holes 32 that are parallel to the axial direction of the rotating shaft 11 and provided at predetermined angles in the circumferential direction. The inertia of the rotor 30 can be reduced by the corresponding weight reduction, and the responsiveness of the motor including the rotor 30 can be improved.

  The plurality of holes 32 are arranged at the same distance from the rotary shaft 11, and the magnetic path width W 4 between the inner peripheral surface of the rotor back yoke 31 and the inner peripheral surface of each hole 32, The magnetic path width W5 between the inner peripheral surface and the outer peripheral surface of the rotor back yoke 31 and the magnetic path width W6 between each hole 32 and the hole 32 ensure a magnetic path width that does not cause saturation of the magnetic flux. Even if a method of creating a magnet by magnetizing the magnetic material after providing a ring-shaped magnetic material that is not divided on the outer periphery of the rotor back yoke 31 is adopted, It is not necessary to perform positioning accurately. Furthermore, even when a method of creating a magnet by performing skew magnetization on the magnetic material so that the magnetic poles are shifted in the circumferential direction as it goes in the axial direction, it is not necessary to provide the holes 32 in a spiral shape. The rotor back yoke 31 can be easily manufactured.

  In particular, even at the angular position where the plurality of holes 32 are disposed, magnetic paths are formed on both sides in the radial direction of the rotor back yoke 31, so that the plurality of holes 32 are formed with respect to a required magnetic path width. The rotor back yoke 31 can be disposed on the outer peripheral side, and in this case, the inertia of the rotor 30 can be further reduced.

  (2) In the present embodiment, the plurality of holes 32 are arranged at the angular position of the central portion of each adjacent notch 12a, so that, for example, the holes 32 and the notches 12a are positioned at the same angular position. As compared with the case where the magnetic path is disposed, the opening area of the hole 32 when a predetermined magnetic path width is secured can be further increased. In this case, the inertia of the rotor can be further reduced.

In addition, you may change the said embodiment as follows.
In the third embodiment, if the press-fit load between the rotating shaft 11 and the rotor back yoke 31 is sufficiently reduced by forming the hole 32, the notch 12a may be omitted. In this case, the shape of the rotor back yoke 31 can be further simplified.

  In the third embodiment, the shape of the hole 32 is not limited to a circle but may be an ellipse or a polygon. The number and arrangement of the holes 32 are also arbitrary. Further, the hole 32 may be a through hole that penetrates the rotor back yoke 31 in the axial direction, but may be a hole that does not penetrate completely.

In each of the above embodiments, the rotor back yoke may be formed by molding (sintering) magnetic powder.
The present invention may be a permanent magnet rotor having a rotor back yoke. For example, the present invention is applied to a DC brush motor having a winding and a commutator on the stator side, and a brush slidably contacting the commutator on the rotor side. You may apply. The power supply to the brush on the rotor side may be performed by an appropriate electrode that is in sliding contact with the electrode on the stator side as it rotates.

  -The thinned portion defined in the present invention substantially reduces inertia such as notches and guides provided in the rotor back yoke in the immediate vicinity of the rotation axis in order to reduce the press-fitting load between the rotation shaft and the rotor back yoke. It should be distinguished from shapes that cannot contribute to

(A) and (b) are the top view and sectional drawing which show the 1st Embodiment of this invention. (A) and (b) are the top view and sectional drawing which show the 2nd Embodiment of this invention. (A) and (b) are the top view and sectional drawing which show the 3rd Embodiment of this invention. (A) and (b) are the top view and sectional drawing which show a conventional form. (A) and (b) are the top view and sectional drawing which show a conventional form.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10, 20, 30 ... Rotor, 11 ... Rotating shaft, 12, 21, 31 ... Rotor back yoke, 12a ... Notch, 12b, 21a, 21b ... Meat removal part, 12c, 21c ... Outer peripheral part, 13 ... Permanent magnet, 32 ... hole.

Claims (6)

In a rotor comprising a rotating shaft, a rotor back yoke fixed so as to rotate integrally with the rotating shaft, and a permanent magnet fixed to the outer peripheral surface of the rotor back yoke,
The rotor back yoke has a thinned portion in a portion excluding the outer peripheral portion in contact with the permanent magnet, and a magnetic path width of the outer peripheral portion is set to a dimension that does not cause saturation of magnetic flux. The rotor according to claim 1, wherein
The rotor is characterized in that the thinned portions are recessed radially outward from the inner peripheral surface at both axial end portions of the rotor back yoke. The rotor according to claim 1, wherein
The rotor according to claim 1, wherein the lightening portion is recessed radially outward from the inner peripheral surface at an axially intermediate portion of the rotor back yoke. In a rotor comprising a rotating shaft, a rotor back yoke fixed so as to rotate integrally with the rotating shaft, and a permanent magnet fixed to the outer peripheral surface of the rotor back yoke,
The rotor back yoke includes a plurality of holes that are parallel to the axial direction of the rotating shaft and provided at predetermined angles in the circumferential direction, and the holes are arranged at the same distance from the rotating shaft, respectively. Magnetic path width (W4) between the inner peripheral surface of the back yoke and the inner peripheral surface of each hole, magnetic path width (W5) between the inner peripheral surface of each hole and the outer peripheral surface of the rotor back yoke, and The rotor is characterized in that the magnetic path width (W6) between the holes is set so as to ensure a magnetic path width that does not cause saturation of the magnetic flux. The rotor according to claim 4, wherein
On the inner peripheral surface of the rotor back yoke, a plurality of notches for reducing a press-fit load when being fixed to the rotating shaft are formed at predetermined angles in parallel with the axial direction,
The rotor, wherein the plurality of holes are arranged at an angular position of a central portion of each adjacent notch. The rotor according to claim 5, wherein
The rotor characterized in that the magnetic path width (W3) between the tip of the notch and the inner peripheral surface of the hole is set so as to ensure a magnetic path width that does not cause saturation of magnetic flux.

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