JP2003032930A - Motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor which can freely provide a digital skew to a rotor magnet at a low cost. SOLUTION: Since the number of magnetic poles of a magnet is 8 and the number of teeth is 12, the least common multiple becomes 24, and cogging can be minimized by displacing the magnetic pole for the value, a half of 15 deg., which is obtained by dividing 360 deg. with the least common multiple 24, namely by 7.5 deg.. If a key groove 21 of the rotating shaft, a groove 31a of the first rotor unit 3a of the first stage and a groove 31c of the second rotor unit 3b of the second stage are aligned and are engaged to fix these with a key 22, by setting the displacing angle θ1 of the groove 31b to 5 deg., displacing an angle θ2 of the groove 31c by 7.5 deg. and a displacing angle θ3 of the groove 31d by 2.5 deg. with reference to the groove 31a, the magnet pole positions of the first rotor unit and second rotor unit are displayed by the angle θ2 of 7.5 deg. in the digital skew.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital skew of a motor having a rotor magnet.

[0002]

2. Description of the Related Art Conventionally, a motor provided with a magnet in a rotor has a torque called a cogging torque which is not related to winding energization because of a stator core having slots for winding and a magnetic flux distribution of the rotor magnet when the rotor rotates. Pulsation occurs.

In order to improve this cogging torque, the rotor is divided into a plurality of stages in the axial direction, and the magnetic pole position of each stage is shifted by a predetermined angle and fixed, thereby providing a digital skew to reduce the cogging torque. The method was taken. A key has been used as an engaging means for the rotor unit and the rotating shaft.

[0004]

As a method of providing a digital skew between the rotor units, there is a method of providing a key groove on the outer circumference of the rotary shaft at a position corresponding to the digital skew angle. However, this method has a drawback that machining of the rotary shaft becomes complicated.

As another method, if the key grooves of the rotary shaft are arranged in a line in the axial direction and the key grooves are provided at positions corresponding to the digital skew angle on each rotor unit side, the center of the magnet magnetic pole and the key groove are formed. Since it is necessary to change the relative position of the rotor core, the number of types of rotor cores increases, and as the number of laminated layers of the rotor unit increases, the number of types of rotor cores increases accordingly, which is a factor of cost increase.

SUMMARY OF THE INVENTION The present invention solves such a conventional problem, and an object of the present invention is to provide an inexpensive motor which can freely provide a digital skew to a rotor magnet.

[0007]

In order to solve the above problems, the present invention comprises a stator having a coil wound around a tooth portion of a laminated core, and a rotor having a gap in the radial direction with the laminated core. In the motor, the rotor is composed of a rotor unit composed of a rotor core laminated in a predetermined size in the axial direction and a plurality of magnets equally divided and arranged, a rotary shaft having a key groove, and a key. , A plurality of groove portions are provided at angular positions displaced from the uniform division in the circumferential direction, and when the rotor units are laminated in a plurality of stages in the axial direction, a predetermined deviation is caused between the magnets of the rotor units due to the angle difference of the groove portions. A corner (digital skew) is provided.

[0008]

In order to solve the above problems, a motor according to a first aspect of the present invention comprises a stator having a coil wound around a tooth portion of a laminated core, and a rotor having a gap in the radial direction with the laminated core. In the motor including, the rotor includes a rotor unit configured by a rotor core laminated in a predetermined dimension in the axial direction and magnets evenly arranged in a plurality, a rotary shaft having a key groove, and a key, The rotor core is provided with a plurality of groove portions at angular positions that are offset from the uniform division in the circumferential direction. Since the predetermined deviation angle (digital skew) is provided, the predetermined digital skew can be easily provided, and the groove portion of the rotor unit can be easily provided. The combination makes it possible to create a rotor of a different deviation angle in one type of rotor core.

The motor according to claim 2 is 360 °.
A half of the angle obtained by dividing by the least common multiple of the number of magnetic poles of the magnet and the number of teeth is the deviation angle (digital skew) in the entire stacking direction, and the digital skew can be optimized.

Further, when the motor according to the third aspect is used for a rotor with a built-in magnet, the same rotor core can share a positioning function for mounting a magnet and providing a digital skew.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

In FIGS. 1 and 2, 1 is a stator, 2 is a rotating shaft, 3 is a rotor, 4 is a coil, and 5 is a gap. Reference numeral 21 is a single key groove, which is provided in the axial direction of the rotary shaft 2. 22 is a key.

The stator 1 has a laminated core 11 divided into 12 parts.
After the concentrated winding, the coils 4 are joined to each tooth portion 12 in an annular shape. A radial gap 5 between the magnet 32 and the laminated core 11 is formed while rotatably supporting the rotating shaft 2 of the rotor 3 by ball bearings housed in the left and right brackets (FIG. 1).

The rotor 3 comprises a rotor core 30 made of steel plate.
Is laminated in a predetermined number, and eight rotor units in which eight magnetic poles of the magnet 32, which are evenly divided, are alternately arranged, are stacked on the outer periphery thereof (FIG. 2).

The central portion of the rotor core 30 has grooves 31a, 31b, 31c and 31 formed in the holes into which the rotary shaft 2 is fitted.
d is provided, the groove portion 31a is located at the center of the magnetic pole of the magnet, and the other groove portions are provided at positions displaced by different angles (θ1, θ2, θ3) from the center of the magnetic pole of the same pole (FIG. 1). . The digital skew can be changed by the combination of the angle differences.

FIG. 3 is a perspective view of an example in which a digital skew is provided between two-layered rotor units. A method for determining the digital skew angle will be described with reference to FIGS. 1 and 2.

Since the number of magnet magnetic poles is 8 and the number of teeth is 12, this least common multiple is 24. To minimize cogging, 360 ° is divided by 24, which is the least common multiple, to obtain a value of 1
It suffices to shift the magnetic pole by ½ of 5 °, that is, by 7.5 °.

Assuming that the deviation angle θ1 of the groove portion 31b is 5 ° with reference to the groove portion 31a, the deviation angle θ2 of the groove portion 31c is the same.
Is 7.5 ° and the deviation angle θ3 of the groove 31d is 2.5 °.

The key groove 21 of the rotary shaft 2, the groove portion 31a of the first rotor unit 3a of the first stage and the groove portion 31c of the second rotor unit 3b of the second stage are aligned and engaged and fixed by the key 22. As a result, the magnet magnetic pole positions of the first rotor unit 3a and the second rotor unit 3b have an angle θ2.
The digital skew is shifted by (7.5 °).

When the groove portion 31a and the groove portion 31b are combined, the digital skew is offset by an angle θ1 (5 °). Similarly, if the groove portion 31b and the groove portion 31c are combined, the angle (θ1
The digital skew is shifted by −θ2 = 2.5 °.

By the way, in order to obtain a digital skew of 7.5 ° by laminating the same rotor unit in four stages, the first stage has the groove portion 31a, the second stage has the groove portion 31d, the third stage has 31b, and 4b.
If the steps 31c are aligned and fixed with a key, they can be displaced by 2.5 ° between the units and can be displaced by 7.5 ° as a whole (not shown).

In this way, the number of groove portions of the rotor core and the angle difference thereof are set so that the desired digital skew angle can be obtained according to the number of magnetic poles and the number of slots. As a result, a plurality of digital skews can be obtained from one type of rotor core, and a motor with a small cogging torque can be obtained.

Even if the number of magnetic poles and the number of slots are different, the digital skew can be similarly formed. Although not shown, the magnet is not limited to the exterior type but may be implemented in the interior type as well, so that the same rotor core can share the positioning function for mounting the magnet and providing the digital skew.

The cogging torque is generated by a magnetic factor, and any winding method such as concentrated winding and distributed winding may be used, and since it is generated by relative movement of the slot (or teeth) and the magnet. It is not limited to only slot opening as in the present embodiment.

[0025]

As is apparent from the above embodiment, according to the invention described in claim 1, it is possible to obtain plural kinds of digital skews with one kind of rotor core.

Further, according to the second aspect of the present invention, since a suitable digital skew can be provided corresponding to the laminated thickness, the cogging torque of the motor can be reduced.

Further, according to the third aspect of the present invention, the same rotor core can share the positioning function for mounting the magnet and providing the digital skew.

Therefore, it is possible to inexpensively and freely provide a digital skew to the rotor magnet, and to obtain a motor with small cogging.

[Brief description of drawings]

FIG. 1 is a sectional view illustrating a digital skew according to an embodiment of the present invention.

FIG. 2 is a vertical sectional view of a motor according to an embodiment of the present invention.

FIG. 3 is a perspective view of a rotor according to an embodiment of the present invention.

[Explanation of symbols]

1 stator 2 rotation axes 3 rotor 3a, 3b rotor unit 4 coils 5 gap 11 laminated core 12 Teeth 21 keyway 22 keys 30 rotor core 31a, 31b, 31c, 31d Groove part 32 magnets

Claims (3)

[Claims] 1. A motor including a stator having a coil wound around a tooth portion of a laminated core, and a rotor having a gap in the radial direction with the laminated core, wherein the rotor is a rotor core laminated in a predetermined dimension in an axial direction. And a rotor unit composed of a plurality of magnets that are equally divided and arranged, a rotary shaft having a key groove, and a key. The rotor core is provided at a plurality of angular positions shifted from the even division in the circumferential direction. When the rotor units are stacked in a plurality of stages in the axial direction, a predetermined deviation angle (digital skew) is provided between the magnets of the rotor units due to the difference in angle between the grooves. motor. 2. The motor according to claim 1, wherein a half of an angle obtained by dividing 360 ° by the least common multiple of the number of magnetic poles of the magnet and the number of teeth is a deviation angle (digital skew) in the entire stacking direction. 3. The motor according to claim 1, wherein the rotor is of a magnet internal type.