JP2015142439A - rare earth magnet motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rare earth magnet motor increased in rigidity of a stator core and a rotor yoke while reduced in size and lightened in weight of a motor.SOLUTION: In a rare earth magnet motor, a stator core 4 is integrally molded with a housing 2 without discontinuity by a dust core made by compression molding of magnetic powder having an insulation film formed on a surface thereof, and a rotor yoke 9 is integrally molded with an output axis 8 without discontinuity by a dust core made by compression molding of magnetic powder having an insulation film formed on a surface thereof. A recessed portion 20 in which a coil is accommodated is formed on an inner peripheral surface of the housing 2, on both end sides of the stator core 4 in the axial direction.

Description

  The present invention relates to a rare earth magnet motor that is used for driving, for example, a joint portion of a robot and includes a stator and a rotor.

Conventionally, a motor has an annular stator in which a coil is wound around a stator core.
The stator core may be a laminated core formed by laminating electromagnetic steel plates such as silicon steel plates in the axial direction, or may be a dust core formed by compression molding a powder magnetic material.

  Patent Document 1 describes a stator core composed of an assembly of a laminated core and a dust core, and the stator core includes a pair of dust cores disposed at both ends in the axial direction, and the pair of dust cores. And a laminated core disposed between the powder magnetic cores.

JP2007-306740

However, this prior art has a problem that the stator core is composed of two members, a laminated core and a dust core, and a gap is formed in the portion where the two members are joined together, so that the rigidity of the stator core is reduced. there were. In addition, the magnetic resistance is increased due to the gap between the two members, and the magnetic flux density generated by the stator is weakened, which may reduce the output torque of the motor.
In addition, since the stator core and the housing are separate members, the assembly process is complicated and the manufacturing cost increases, and the outer diameter of the motor increases.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a rare earth magnet motor in which the rigidity of the stator and the rotor is increased while reducing the size and weight of the motor.

In order to achieve such an object, a rare earth magnet motor according to the present invention includes a stator having a stator core to which a plurality of coils are fixed, and a rotor having a rotor core in which a plurality of rare earth magnets are arranged at equal intervals in the circumferential direction. And the rotor is arranged coaxially so as to be rotatably opposed to the stator.
In particular, the rare earth magnet motor of the present invention is characterized in that it comprises at least one of a housing formed integrally with the stator core without a break and an output shaft formed integrally with the rotor yoke without a break.

  Furthermore, the stator core and the rotor yoke are preferably dust cores. Furthermore, it is preferable that a recess for accommodating a coil is formed on the peripheral surface of the housing on both axial ends of the stator core.

ADVANTAGE OF THE INVENTION According to this invention, the rare earth magnet motor which improved the rigidity of the stator and the rotor can be provided, aiming at size reduction and weight reduction of a motor.
That is, the rare earth magnet motor of the present invention has a structure in which the stator core and the housing, or the rotor yoke and the output shaft are seamlessly integrated so that the electromagnetic steel sheets are laminated and fixed, or the laminated core is fixed to the housing or the output shaft. There is no need to fix to. As a result, a member and a mechanism for fixing the stator core to the housing or a member and a mechanism for fixing the rotor yoke to the output shaft are not necessary, so that the motor can be reduced in size and weight. And since there is no gap between the stator core and the housing, a stator core having excellent magnetic properties can be manufactured. Furthermore, since the stator core is firmly coupled to the housing and the rotor yoke is firmly coupled to the output shaft, the rigidity of the stator and the rotor can be increased, and the performance of the motor using these can be improved.
In particular, in the present invention, since at least one of the stator and the rotor described above is provided, a high-torque, low-vibration rare earth magnet motor can be provided at low cost. This is because an attraction force is generated between the rotor and the stator, but the stator core and the rotor yoke described above have improved rigidity, so that the vibration caused by the attraction force and the repulsive force acting between the rotor and the stator is reduced. This is because the increase can be more effectively suppressed.

It is a figure which shows the internal structure of the motor concerning the 1st Embodiment of this invention. It is a top view of the stator and rotor of FIG. It is a top view of the stator and rotor concerning the motor of the 2nd Embodiment of this invention. It is a top view of the stator and rotor concerning the motor of the 3rd Embodiment of this invention. It is a figure which shows the internal structure regarding the motor of the 4th Embodiment of this invention. It is a top view of the stator and rotor of FIG.

(First embodiment)
Hereinafter, a first embodiment for carrying out the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing an internal structure of a rare earth magnet motor according to the present embodiment, and FIG. 2 is a plan view of a stator and a rotor. In the present embodiment, the motor 1 is an inner rotor type direct drive (DD) motor, but the type of the motor is not limited to this.

  The motor 1 includes a stator core 4 and a rotor yoke 9, and further includes a housing 2, an output shaft 8, and a bearing 11. The stator core 4 is an annular structure formed on the inner periphery of the housing 2 that is a cylindrical structure, and the rotor yoke 9 is an annular structure formed on the outer periphery of the output shaft 8 that is a cylindrical structure. It is a structure. Since the motor 1 is an inner rotor type direct drive motor, the rotor yoke 9 is disposed on the radially inner side of the stator core 4, and the output shaft 8 has a hollow hole 23 in the inner diameter portion.

  The stator core 4 is a powder magnetic core formed integrally with the housing 2 by compression molding magnetic powder having an insulating film formed on the surface thereof. Similarly, the rotor yoke 9 is a dust core formed integrally with the output shaft 8 by compression molding a magnetic powder having an insulating film formed on the surface thereof. The rotor yoke 9 constitutes the rotor 7 together with a plurality of rare earth magnets 10 arranged on the outer peripheral surface of the rotor yoke 9 at equal intervals in the circumferential direction. The stator core 4 constitutes the stator 3 together with the plurality of coils 5 arranged in the plurality of slots 6, and the rotor 7 is rotated by sequentially supplying electric power from the power line 19 to each coil 5. The output shaft 8 is connected to a drive target (not shown) of the motor 1, and the stator 3 rotates the rotor yoke 9 formed integrally with the output shaft 8 through the output shaft 8. , Drive the drive target. At both ends in the axial direction of the motor 1, mounting holes 21 for fixing the motor 1 and coupling a drive target are provided.

  A pair of resolver supports 17, which are cylindrical members, are attached to one end of the motor 1 in the axial direction in order to arrange a resolver 16 that detects the rotation angle of the output shaft 8. The resolver support 17 is made of a nonmagnetic material such as aluminum or stainless steel so as not to affect the detection accuracy of the resolver 16. One of the resolvers 16 is disposed on the housing 2 that is a stationary system, and the other is disposed on the output shaft 8 that is a rotating system. The rotation angle of the output shaft 8 relative to the housing 2 detected by the resolver 16 is output from the sensor line 18 as an electrical signal.

On both sides in the axial direction of the output shaft 8, the inner ring 13 of the bearing 11 is attached with bolts via the bearing ring attachment 15 and the resolver support 17, and the outer ring 12 of the bearing 11 is attached to the housing 2. Each bearing 11 is a ball bearing in which a plurality of balls 14 are arranged to freely roll between an inner ring 13 and an outer ring 12, and are assembled in a state in which a preload is applied by a back surface combination (DB). With such a structure, the output shaft 8 is rotatably supported in a state in which both an axial load and a radial load can be supported with respect to the housing 2. At this time, the rotor 7 and the output shaft 8 rotate around the rotation center axis Zr of the motor 1. The bearing 11 is not limited to a ball bearing, and may be a cross roller bearing capable of supporting an axial load and a radial load at the same time.
Next, the structure of the stator core 4 and the rotor yoke 9 will be described in more detail.

  The stator core 4 is a powder magnetic core formed by compression-molding magnetic powder whose surface is covered with an insulating film, and is formed simultaneously with the housing 2 so that the stator core 4 and the housing 2 are integrated. . As shown in FIG. 2, the stator core 4 has a plurality of slots 6 for accommodating the coils 5, and the coil 5 in a state where an electric wire is wound around a bobbin is inserted into the slots 6, It is fixed to the stator core 4. On the inner peripheral surface of the housing 2 at both axial ends of the stator core 4, recesses 20 for accommodating the coils 5 are formed. In the present embodiment, the stator 3 has 30 coils 5.

  The rotor yoke 9 is a powder magnetic core formed by compression molding magnetic powder whose surface is covered with an insulating film, and is formed simultaneously with the output shaft 8 so that the rotor yoke 9 and the output shaft 8 are integrated. ing. In the rotor 7, a plurality of permanent magnets 10 are arranged on the outer peripheral surface of the rotor yoke 9 at equal intervals in the circumferential direction. And the said output shaft 8 is a cylindrical structure, and has the hollow hole 23 in the internal diameter part. In the present embodiment, the diameter of the hollow hole 23 is 60% of the outer diameter of the motor 1, and both axial ends of the output shaft 8 (including the resolver support 17) are located at the housing 2 (resolver support 17. Projecting from both axial end faces. The stator core 4 and the rotor yoke 9 are annular structures, and their center axes coincide with the rotation center axis Zr of the motor 1.

With the configuration as described above, the rare earth magnet motor of the present embodiment can increase the rigidity of the stator 3 and the rotor 7 while reducing the size and weight of the motor 1.
That is, in the motor 1 of the present invention, by making the stator core 4 and the housing 2 or the rotor yoke 9 and the output shaft 8 as an integrated structure, welding or caulking or the like when laminating and fixing the electromagnetic steel sheets becomes unnecessary. Furthermore, it is not necessary to fix the laminated core to the housing 2. As a result, since the member and mechanism for fixing the stator core 4 to the housing 2 or the member and mechanism for fixing the rotor yoke 9 to the output shaft 8 are not required, the motor 1 can be reduced in size and weight.

  Further, by providing a recess 20 for housing the coil 5 on the inner peripheral surface of the housing 2, the radial dimension of the stator core 4 and the winding space of the coil 5 are secured. This is because the stator core 4 having a larger diameter than the inner diameter of the housing 2 can be formed because it is not necessary to incorporate a stator core as a separate member into the inner diameter of the housing as in the prior art. That is, both axial end portions of the housing 2 to which the bearing 11 is attached secure a wall thickness (inner diameter dimension) necessary for holding the bearing 11, while an axial intermediate portion of the housing 2 where the stator core 4 is formed is thin. As described above, expansion of the outer diameter of the housing 2 is suppressed while ensuring the diameter of the stator core 4. By providing the recess 20, interference between the coil 5 housed in the stator core 4 and the housing 2 is avoided. As described above, by integrating the housing 2 and the stator core 4, the outer diameter of the housing 2 can be reduced.

Similarly, by integrating the rotor yoke 9 with the output shaft 8 and sharing a part of the rotor yoke 9 as the structure of the output shaft 8, the intermediate portion in the axial direction of the output shaft 8 is made thin, and the radial direction of the output shaft 8 The expansion of the width dimension is suppressed. Therefore, the diameter of the hollow hole 23 provided in the inner diameter of the output shaft 8 can be increased, and the output shaft 8 can be reduced in size and weight. Further, since the yoke can be thinned by increasing the number of poles, the hollow hole can be enlarged.
Furthermore, the motor 1 can be further reduced in size by using the bearing 11 in which the outer ring 12 and the inner ring 13 are thin.

And since there is no gap between the stator core 4 and the housing 2, it is possible to manufacture the stator core 4 in which deterioration of magnetic properties is suppressed. Further, since the stator core 4 is firmly connected to the housing 2 and the rotor yoke 9 is firmly connected to the output shaft 8, the rigidity of the stator 3 and the rotor 7 is improved, and the performance of the motor using these is improved. Can do.
In particular, in the present invention, since it has at least one of the housing 2 and the output shaft 8 described above, a high-torque, low-vibration rare earth magnet motor can be provided. In the rare earth magnet motor, an attractive force and a repulsive force act between the rotor yoke 9 and the stator core 4. However, since the stator core 4 and the rotor yoke 9 described above have improved rigidity, the rotor yoke 9 and the stator core 4 This is because it is possible to more effectively suppress an increase in vibration due to the attractive force and the repulsive force acting between the two.

(Second Embodiment)
FIG. 3 is a plan view of a stator and a rotor of a rare earth magnet motor according to the second embodiment of the present invention. A housing mounting hole 22 for fixing the motor is provided on the outer peripheral surface of the housing 2a of the rare earth magnet motor of the present embodiment. The housing mounting hole 22 is a tap hole provided in a direction parallel to a line orthogonal to the rotation center axis Zr of the housing 2a, and is formed integrally with the housing 2a. The housing 2a can be mounted from the radial direction by screwing the bolt into the housing mounting hole 22 and tightening. Other configurations are the same as those of the first embodiment of the present invention described above, and have the same functions and effects.

(Third embodiment)
FIG. 4 is a plan view of a stator and a rotor of a rare earth magnet motor according to the third embodiment of the present invention. A housing mounting hole 22a for fixing the motor is provided on the outer peripheral surface of the housing 2b of the rare earth magnet motor of the present embodiment. The housing mounting hole 22a is a hole penetrating in a direction parallel to a line orthogonal to the rotation center axis Zr of the housing 2b, and is formed integrally with the housing 2b. The housing 2b can be mounted from the radial direction by inserting a bolt into the housing mounting hole 22a and tightening with a nut. Other configurations are the same as those of the first embodiment of the present invention described above, and have the same functions and effects.

(Fourth embodiment)
FIG. 5 is a diagram showing an internal structure of a rare earth magnet motor according to the fourth embodiment of the present invention, and FIG. 6 is a plan view of a stator and a rotor. The rare earth magnet motor of the present embodiment is an outer rotor type direct drive motor, and the rotor 7a is disposed on the radially outer side of the stator 3a. Compared to the first embodiment, the housing 2c, the stator core 4a, the output shaft 8a, and the rotor 9a are interchanged, and the rotating output shaft 8a is located on the outer diameter side, so a higher torque is required. Suitable for use. Other configurations are the same as those of the first embodiment of the present invention described above, and have the same functions and effects.

As described above, each embodiment can provide a rare earth magnet motor with high torque and low vibration.
In addition, although each embodiment demonstrated the direct drive type rare earth magnet motor, embodiment is not limited to the content mentioned above. For example, in each embodiment, although the dust core was shown as a material of a stator core and a rotor yoke, iron (casting) can also be used if it is a use which can tolerate an iron loss. In addition, constituent elements in the above-described embodiments include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those in a so-called equivalent range.

  The rare earth magnet motor of the present invention can be suitably applied to applications such as mechanical parts, for example, joint portions of robots.

DESCRIPTION OF SYMBOLS 1, 1a Motor 2, 2a, 2b, 2c Housing 3, 3a Stator 4, 4a Stator core 5 Coil 6 Slot 7, 7a Rotor 8, 8a Output shaft 9, 9a Rotor yoke 10 Rare earth magnet 11 Bearing 12 Outer ring 13 Inner ring 14 Ball 15, 15a bearing ring fixture 16 resolver 17 resolver support 18 sensor wire 19 power line 20 recess 21 mounting hole 22, 22a housing mounting hole 23, 23a hollow hole Zr rotation center shaft

Claims (3)

A stator having a stator core to which a plurality of coils are fixed; and a rotor having a rotor yoke in which a plurality of rare earth magnets are arranged at equal intervals in the circumferential direction. In the rare earth magnet motor disposed on the housing, the stator core and the housing formed integrally with the cut, the rotor yoke and the output shaft formed integrally with the cut, and
A rare earth magnet motor comprising at least one of the following.   2. The rare earth magnet motor according to claim 1, wherein a concave portion for accommodating a coil is formed on a peripheral surface of the housing on both axial ends of the stator core.   The rare earth magnet motor according to claim 1, wherein the stator core and the rotor core are dust cores.

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