JP2005045978A - Motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brushless DC motor which has high assemblability and is capable of using magnets having high magnetic flux density. <P>SOLUTION: A segment magnet 28 is accommodated in a comb tooth 22b of the ring magnets 22A, 22B to manufacture a rotor 20, thus providing high assemblability of the magnet. The segment magnet 28 having high magnetic power is assembled into the ring magnets 22A, 22B having low magnetic power, thus obtaining strong magnetic flux with the rotor 20. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a motor having magnets on the outer periphery of a rotor or the inner periphery of a stator.

As shown in FIG. 7 (B), the rotor (rotor) of the brushless DC motor has a plurality of rod-shaped segment magnets 28 arranged on the surface of the rotor 120 as shown in FIG. 7 (A). The thing which has arrange | positioned the anisotropic ring magnet 22 formed in the cylinder shape on the surface of the rotor 120 is used. For example, a radial anisotropic ring magnet in which different polarities are simply magnetized in the radial direction alternately in the circumferential direction, or a radial direction in which the magnetic flux entering the magnet from the radial direction is bent in the circumferential direction. (See Non-Patent Document 1 below), all of which are used for rotors (rotors) of brushless DC motors.
Hitachi Metals, Ltd. Internet homepage, product information / magnet / neodymium sintered anisotropic ring magnet [searched on June 6, 2003], Internet <URL; http://www.hitachi-metals.co .jp / prod / prod03 / p03_01_d.html>

  When the segment magnet is used, the magnetic force of the segment magnet itself is strong, so that positioning accuracy in the circumferential direction is required to reduce the cogging torque and torque ripple, but the assemblability has been lowered to ensure the accuracy. Furthermore, in order to reduce the cogging torque and torque ripple, it is necessary to dispose the segment magnets obliquely with respect to the axis in order to add skew, which makes it very difficult to assemble.

  On the other hand, ring magnets can be magnetized after they are assembled, so they are easy to assemble and are easy to skew magnetize. On the other hand, they are hardened with resin compared to segment magnets. There was a problem of being weak.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide a motor that can be used with a magnet having a high magnetic flux density and high assemblability.

In order to achieve the above object, the invention of claim 1 is a motor having magnets on the outer periphery of the rotor or the inner periphery of the stator.
A technical feature is that the rotor or the stator is formed of a ring magnet, and the segment magnet is accommodated in a recess provided in the ring magnet.

The invention of claim 2 is a motor having a magnet on the outer periphery of the rotor,
The rotor is composed of a pair of ring magnets, and a segment magnet is accommodated in a comb-shaped recess provided in the ring magnet, and the comb-shaped tips of the pair of ring magnets are brought into contact with each other.

The invention of claim 3 is a motor having a magnet on the outer periphery of the rotor,
The rotor is composed of a ring magnet, and the technical feature is that the segment magnet is accommodated in a recess provided in the axial direction on the outer periphery of the ring magnet.

  Since the motor according to claim 1 can manufacture the rotor or the stator by housing the segment magnet in the concave portion of the ring magnet, the magnet can be easily assembled. In addition, since a segment magnet having a large magnetic force is incorporated into a ring magnet having a small magnetic force, a strong magnetic flux density can be obtained with a rotor or a stator. Furthermore, since the segment magnet is accommodated in the concave portion of the ring magnet, even if the segment magnet is peeled off, the concave portion serves as a detent and the safety is improved. Therefore, when used for a motor such as an electric power steering apparatus, the mechanical reliability can be improved. In addition, since a ring magnet that can be magnetized after assembly is used, skew magnetization for making the magnetic flux uniform in the circumferential direction can be easily performed, and smooth rotation can be realized by reducing cogging torque and torque ripple. .

  In the motor according to the second aspect, since the rotor can be manufactured by housing the segment magnet in the concave portion of the comb teeth of the ring magnet, the magnet can be easily assembled. Further, since a segment magnet having a large magnetic force is incorporated into a ring magnet having a small magnetic force, a strong magnetic flux density can be obtained with the rotor. Furthermore, since the segment magnet is accommodated in the concave part of the comb teeth of the ring magnet, even if the segment magnet is peeled off, the concave part serves as a detent and the safety is improved. Further, since the segment magnets are accommodated in the concave portions of the comb teeth provided on the pair of ring magnets, even if the ring magnets are separated from each other, the segment magnets can prevent the ring magnets from rotating and the safety is improved. Therefore, when used for a motor such as an electric power steering apparatus, the mechanical reliability can be improved. In addition, since a ring magnet that can be magnetized after assembly is used, skew magnetization for making the magnetic flux uniform in the circumferential direction can be easily performed, and smooth rotation can be realized by reducing cogging torque and torque ripple. .

  Since the rotor of a motor of Claim 3 can manufacture a rotor by accommodating a segment magnet in the recessed part of a ring magnet, the assembly | attachment property of a magnet is high. Further, since a segment magnet having a large magnetic force is incorporated into a ring magnet having a small magnetic force, a strong magnetic flux density can be obtained with the rotor. Furthermore, since the segment magnet is accommodated in the concave portion of the ring magnet, even if the segment magnet is peeled off, the concave portion serves as a detent and the safety is improved. Therefore, when used for a motor such as an electric power steering apparatus, the mechanical reliability can be improved. In addition, since a ring magnet that can be magnetized after assembly is used, skew magnetization for making the magnetic flux uniform in the circumferential direction can be easily performed, and smooth rotation can be realized by reducing cogging torque and torque ripple. .

  Further, when the motor according to claim 3 is composed of a plurality of ring magnets, the segment magnets are accommodated in the recesses provided in the plurality of ring magnets, so even if the ring magnets are separated from each other, the segment magnets This prevents the rotation of the ring magnet and improves safety.

  By placing the segment magnet in the center of the pole in the circumferential direction as viewed from the rotor and parallel to the axis, a segment magnet with strong magnetic force is placed at the center of the pole, and the magnetic force between the poles Since a weak ring magnet is disposed, smooth magnetic flux switching can be created, and the motor can be smoothly rotated.

Embodiments of a DC motor according to the present invention will be described below with reference to the drawings.
[First embodiment]
A brushless DC motor 10 according to a first embodiment of the present invention will be described with reference to FIGS. This brushless DC motor 10 is used for steering assist of an electric power steering apparatus.
FIG. 3 shows a cross section of the brushless DC motor 10. The brushless DC motor 10 is mainly composed of a rotor 20 in which a ring magnet 22 and a segment magnet 28 are provided on the outer periphery of a rotating shaft 12, and a stator 30 provided on the entire periphery of the rotor 20. Yes. In addition, the housing which accommodates these is abbreviate | omitted in FIG.

  The rotor 20 of the brushless DC motor 10 is provided so as to be rotatable about a rotating shaft 12. The rotating shaft 12 passes through the hole 22 a of the ring magnet 22 and rotates together with the ring magnet 22. It is configured to function as a child 20. In other words, the rotational force generated by the rotation of the rotor 20 by the rotating field by the stator 30 can be output from the rotating shaft 12 as motor torque.

  The stator 30 is formed in a cylindrical shape in which laminated steel plates made of a ferromagnetic material formed in an annular shape are stacked, and a coil 34 for generating a rotating field is wound inside the stator 30. 32 is formed.

  A ring magnet and a segment magnet constituting the rotor 20 according to the first embodiment will be described with reference to FIGS. 1 and 2. FIG. 1A is a cross-sectional view of the rotor 20 of the brushless DC motor 10 of the first embodiment, and FIG. 1B is a side view of the rotor 20. FIG. 1A corresponds to a cross section along line AA in FIG. FIG. 2 is an assembly diagram of the ring magnet and the segment magnet that constitute the rotor 20.

  As shown in FIG. 2, each of the pair of ring magnets 22A and 22B is provided with a hole 22a at the center and comb teeth 22b facing each other. Between each comb tooth 22b, the recessed part 22c for accommodating the rod-shaped segment magnet 28 is formed. The concave portions 22c of the ring magnets 22A and 22B are formed so that the segment magnet 28 can be arranged in the center of the pole in the circumferential direction when viewed from the rotor 20 so as to be parallel to the axis. Here, the tips of the comb teeth 22b of the ring magnet 22A and the comb teeth 22b of the ring magnet 22B are brought into contact with each other, and the recess 22c between the comb teeth 22b and 22b of the ring magnet 22A and the comb teeth 22b of the ring magnet 22B, By accommodating the segment magnet 28 in the recess 22c between 22b, the rotor 20 is configured as shown in FIG. 1 (A) and FIG. 1 (B). As described above, by accommodating the segment magnets 28 in the concave portions 22c of the ring magnets 22A and 22, the segment magnets 28 can be arranged at the center of the pole in the circumferential direction as viewed from the rotor 20 so as to be parallel to the axis.

  After assembling to the rotor 20 shown in FIG. 1B, the ring magnets 22A and 22B are magnetized. At this time, as shown by S in the figure, skew magnetization is performed by being magnetized obliquely with respect to the axial direction. Here, the magnets are magnetized after the ring magnets 22A and 22B are assembled to the rotary shaft 12. However, the magnets can be magnetized before the assembly.

  In the first embodiment, the ring magnets 22A, 22B are configured as bond magnets (rubber magnets, plastic magnets, etc.) made of, for example, neodymium / iron / boron or samarium / cobalt. On the other hand, the segment magnet 28 is composed of, for example, a magnet made of neodymium / iron / boron or samarium / cobalt. Since the ring magnets 22 </ b> A and 22 </ b> B are hardened with resin or the like, the magnetic force is weaker than that of the segment magnet 28. The segment magnet 28 is assembled in a magnetized state.

  According to the brushless DC motor 10 of the first embodiment, the rotor 20 can be manufactured by housing the segment magnets 28 in the recesses 22c of the comb teeth 22b of the ring magnets 22A and 22B. Further, since the segment magnet 28 having a large magnetic force is incorporated into the ring magnets 22A and 22B having a small magnetic force, a strong magnetic flux density can be obtained by the rotor 20. Further, since the segment magnet 28 is accommodated in the recess 22c of the comb tooth 22b of the ring magnet 22, even if the segment magnet 28 is peeled off, the recess 22c serves as a detent and improves safety. Furthermore, since the segment magnets 28 are accommodated in the recesses 22c of the comb teeth 22b provided in the pair of ring magnets 22A and 22B, even if the ring magnets 22A and 22B are separated, the recesses 22c of the comb teeth 22b The accommodated segment magnet 28 can prevent the ring magnets 22A and 22B from rotating, thereby improving safety. Therefore, when used in a motor such as an electric power steering apparatus, mechanical reliability can be improved. Furthermore, since the ring magnet 22 that can be magnetized after assembling is used, skew magnetization for making the magnetic flux in the circumferential direction uniform can be easily performed, and smooth rotation can be realized by reducing cogging torque and torque ripple.

  Further, the segment magnet 28 is arranged at the center of the pole in the circumferential direction when viewed from the rotor 20 so as to be parallel to the axis. For this reason, since the segment magnet 28 having a strong magnetic force is arranged at the center of the pole and the ring magnets 22A and 22B having a low magnetic force are arranged between the poles, a smooth switching of the magnetic flux can be created. The DC motor can be smoothly rotated.

[Second Embodiment]
A brushless DC motor 10 according to a second embodiment of the present invention will be described with reference to FIGS. 4 and 5. This brushless DC motor 10 is used for steering assist of an electric power steering apparatus.
FIG. 5 shows a cross section of the brushless DC motor 10. The brushless DC motor 10 is mainly composed of a rotor 20 in which a ring magnet 22 and a segment magnet 28 are provided on the outer periphery of a rotating shaft 12, and a stator 30 provided on the entire periphery of the rotor 20. Yes. The rotor 20 of the brushless DC motor 10 is provided so as to be rotatable about a rotating shaft 12. The rotating shaft 12 passes through the hole 22 a of the ring magnet 22 and rotates together with the ring magnet 22. It is configured to function as a child 20. The stator 30 has a cylindrical shape in which laminated steel plates are stacked, and a plurality of slots 32 are formed inside the stator 30 for winding a coil 34 that generates a rotating field.

  A ring magnet and a segment magnet constituting the rotor 20 according to the second embodiment will be described with reference to FIG. FIG. 4A is a cross-sectional view of a ring magnet constituting the rotor 20 of the brushless DC motor according to the second embodiment, FIG. 4B is a cross-sectional view of the rotor 20, and FIG. 3 is a side view of the rotor 20. FIG. FIG. 4B corresponds to a BB cross section of FIG.

  Each of the pair of ring magnets 22A and 22B is provided with a hole 22a at the center, and the segment magnet 28 can be arranged on the outer periphery at the center of the pole in the circumferential direction when viewed from the rotor 20 so as to be parallel to the axis. A recess 22d is formed on the surface. Here, the side end of the ring magnet 22A and the side end of the ring magnet 22B are brought into contact with each other, and the segment magnets 28 are accommodated in the recesses 22d of the ring magnets 22A and 22B, so that FIGS. ), The rotor 20 is configured. As described above, by accommodating the segment magnets 28 in the recesses 22d of the ring magnets 22A and 22B, the segment magnets 28 can be arranged at the center of the pole in the circumferential direction as viewed from the rotor 20 so as to be parallel to the axis.

  After assembling to the rotor 20 shown in FIG. 4 (C), the ring magnet 22 is magnetized. At this time, as shown by S in the figure, skew magnetization is performed by being magnetized obliquely with respect to the axial direction.

  In the brushless DC motor 10 of the second embodiment, since the rotor 20 can be manufactured by housing the segment magnet 28 in the concave portions 22d of the ring magnets 22A and 22B, the assembling property of the segment magnet is high. Further, since the segment magnet 28 having a large magnetic force is incorporated into the ring magnets 22A and 22B having a small magnetic force, a strong magnetic flux density can be obtained by the rotor 20. Furthermore, since the segment magnets 28 are accommodated in the recesses 22d of the ring magnets 22A and 22B, even if the segment magnets 28 are peeled off, the recesses 22d serve to prevent rotation and improve safety. Therefore, when used for a motor such as an electric power steering apparatus, the mechanical reliability can be improved. Furthermore, since the ring magnet 22 that can be magnetized after assembling is used, skew magnetization for making the magnetic flux in the circumferential direction uniform can be easily performed, and smooth rotation can be realized by reducing cogging torque and torque ripple.

  Further, since the rotor 20 is composed of two ring magnets 22A and 22B, and the segment magnet 28 is accommodated in the recess 22d provided in the plurality of ring magnets 22A and 22B, the ring magnets 22A and 22B are connected to each other. Even if separated, the segment magnets 28 can prevent the ring magnets 22A and 22B from rotating, thereby improving safety. In the first embodiment, the rotor 20 is composed of a pair of ring magnets 22A and 22B. However, in the second embodiment, there is an advantage that the rotor 20 can be easily configured even when three or more ring magnets are used. It can be suitably used for a DC motor having a long length.

[Third embodiment]
A DC motor 100 according to a third embodiment of the present invention will be described with reference to FIG.
In the first embodiment and the second embodiment described above, the ring magnet and the segment magnet are arranged on the rotor 20 side. On the other hand, in 3rd Embodiment, the ring magnet and the segment magnet are used for the stator 30 side.

FIG. 6B shows a cross section of the DC motor 100 according to the third embodiment.
The DC motor 100 mainly includes a rotor 20 fixed to the outer periphery of a rotating shaft 120 and a stator 30 formed by providing a ring magnet 22 and a segment magnet 28 on the inner periphery. The rotor 20 is formed in a cylindrical shape in which laminated steel plates are stacked, and a slot 26 for accommodating a coil 34 that generates a rotating field is formed on the outside thereof.

FIG. 6A is a cross-sectional view of a ring magnet and a segment magnet constituting the stator 30 of the DC motor.
The ring magnet 22 is formed with a recess 22e on the inner periphery so that the segment magnet 28 can be disposed in the center of the pole in the circumferential direction when viewed from the stator 30 so as to be parallel to the axis. By accommodating the segment magnet 28 in the recess 22 e of the ring magnet 22, the segment magnet 28 is arranged at the center of the pole in the circumferential direction as viewed from the stator 30 so as to be parallel to the axis. Although not shown, skew magnetization is performed on the inner periphery of the ring magnet 22 as in the first and second embodiments.

  In 3rd Embodiment, since the stator 30 can be manufactured by accommodating the segment magnet 28 in the recessed part 22e of the ring magnet 22, the assembly | attachment property of a magnet is high. Further, since the segment magnet 28 having a large magnetic force is incorporated into the ring magnet 22 having a small magnetic force, a strong magnetic flux density can be obtained by the stator 30. Furthermore, since the segment magnet 28 is accommodated in the recess 22e of the ring magnet 22, even if the segment magnet 28 is peeled off, the recess 22e serves as a detent and improves safety. Therefore, when used for a motor such as an electric power steering apparatus, the mechanical reliability can be improved. Furthermore, since a ring magnet that can be magnetized after assembly is used, skew magnetization that equalizes the magnetic flux in the circumferential direction can be easily performed, and smooth rotation can be realized by reducing cogging torque and torque ripple.

  In the above-described embodiment, an example in which the configuration of the present invention is applied to a brushless DC motor has been described. However, it goes without saying that the present invention can be applied to various motors using magnets in addition to various DC motors. Furthermore, in the first and second embodiments, a pair (two) of ring magnets are used, but a single ring magnet can be used.

FIG. 1A is a cross-sectional view of the rotor of the brushless DC motor according to the first embodiment, and FIG. 1B is a side view of the rotor. It is an assembly drawing of the ring magnet and segment magnet which comprise a rotor. It is sectional drawing of the brushless DC motor which concerns on 1st Embodiment. 4A is a cross-sectional view of a ring magnet constituting the rotor of the brushless DC motor of the second embodiment, FIG. 4B is a cross-sectional view of the rotor, and FIG. 4C is a rotor. FIG. It is sectional drawing of the brushless DC motor which concerns on 2nd Embodiment. FIG. 6A is a cross-sectional view of a ring magnet and a segment magnet constituting the stator of the DC motor of the third embodiment, and FIG. 6B is a cross-sectional view of the DC motor according to the third embodiment. FIG. 7A is a perspective view of a rotor using a segment magnet according to the prior art, and FIG. 7B is a perspective view of a rotor using a ring magnet.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Brushless DC motor 12 Rotating shaft 20, 120 Rotor 22, 22A, 22B Ring magnet 22a Hole 22b Comb tooth 22c Recessed 22d Recessed 26 Slot 28 Segment magnet 30 Stator 32 Slot 34 Coil 100 DC motor

Claims (6)

In a motor having magnets on the outer periphery of the rotor or the inner periphery of the stator,
A motor characterized in that a rotor or a stator comprises a ring magnet, and a segment magnet is accommodated in a recess provided in the ring magnet. In a motor having a magnet on the outer periphery of the rotor,
A motor characterized in that the rotor is composed of a pair of ring magnets, a segment magnet is accommodated in a comb-shaped recess provided in the ring magnet, and the comb-teeth tips of the pair of ring magnets are brought into contact with each other. In a motor having a magnet on the outer periphery of the rotor,
A motor characterized in that a rotor is made of a ring magnet, and a segment magnet is housed in a recess provided in an axial direction on the outer periphery of the ring magnet.   The motor according to claim 3, wherein the ring magnet includes a plurality of ring magnets.   The motor according to any one of claims 2 to 4, wherein the segment magnet is disposed at a position that becomes a center of a pole in a circumferential direction with respect to the rotor. 6. The motor according to claim 1, wherein skew magnetizing is performed on the ring magnet.

Images