JP2021010284A - Outer rotation type surface magnet rotating electric machine - Google Patents

Abstract

To provide an outer rotation type surface magnet rotating electric machine that reduces torque ripple while reducing the disadvantages of magnet breakage and increase in magnetoresistance.SOLUTION: An outer rotation type surface magnet rotating electric machine includes a rotor having a rotor core and a permanent magnet arranged on the inner diameter side of the rotor core, and a stator having a stator core arranged on the inner diameter side of the rotor via a gap, and a coil attached to the stator core, and the rotor core has a plurality of voids per pole on the outer diameter side of the surface to which the permanent magnet is attached.SELECTED DRAWING: Figure 2

Description

The present invention relates to an abduction type surface magnet rotating electric machine.

The rotary electric machine, which is an electric / mechanical energy conversion device, is built in various devices, and as the devices are miniaturized, the rotary electric machine is also required to be miniaturized. An abduction type permanent magnet rotary electric machine is used as one of the means for miniaturizing the rotary electric machine. The abduction type permanent magnet rotating electric machine has a configuration in which a rotor with a permanent magnet is arranged on the outer peripheral side of a stator to which a coil is attached. Compared to the adduction type permanent magnet rotary electric machine, the abduction type permanent magnet rotary electric machine has a larger radius of the gap between the rotor and the stator, and the circumference of one pole is longer because the rotor is on the outside. Therefore, there is a feature that a magnet having a large area when viewed from the radial direction can be arranged. As a result, the output can be increased and the rotary electric machine can be miniaturized.

Since the abduction type permanent magnet rotating electric machine has a rotor iron core on the outer peripheral side of the magnet, there is little problem of holding the magnet against centrifugal force, so that the surface magnet type is often used. Since the surface magnet type reduces short circuits of magnetic flux in the rotor core, the effective magnetic flux can be increased and the output can be increased.

One of the issues of rotary electric machines is reduction of torque ripple. Torque ripple is the pulsation of torque. Torque ripple causes vibration and noise of the drive unit.

Regarding the reduction of torque ripple, there is a technique described in Patent Document 1. The rotor of a rotary electric machine includes a substantially annular rotor core having a plurality of magnet insertion holes formed at predetermined intervals in the circumferential direction, and a permanent magnet inserted into the magnet insertion holes. The rotor core is formed by laminating a large number of electromagnetic steel sheets, and is characterized in that a hole portion is provided on the substantially d-axis of each magnetic pole portion formed of a permanent magnet on the outer peripheral side of the magnet insertion hole of the rotor core.

Further, regarding the reduction of torque ripple, there is a technique described in Patent Document 2. A magnet holding portion having a cylindrically shaped multi-pole magnetized magnet and a back yoke provided in contact with one surface of the magnet in the radial direction, and a magnetic field generating portion located opposite to the other surface of the magnet. In a spindle motor in which one of the magnet holding portion and the magnetic field generating portion is rotatably provided, the back yoke has a surface on the side where the magnet comes into contact with the magnetic poles adjacent to the magnet. It is characterized in that a recess is provided along the boundary line.

JP 2018-137924 JP 2001-57752

In Patent Document 1, torque ripple is reduced by providing a gap on the gap side with respect to the magnet. However, in the surface magnet type, it is difficult to adapt because the magnet faces the gap.

In Patent Document 2, torque ripple is reduced by providing a groove (non-magnetic portion) on the outer shape side of the magnet end portion. However, since the magnetic resistance increases due to the non-magnetic portion, the magnetic flux at the end of the magnet cannot be effectively used. Further, when an impact is applied to the magnet for some reason, there is a high possibility that the magnet will be damaged because there are few members for holding the magnet.

An object of the present invention is to provide an abduction type surface magnet rotating electric machine that reduces the demerits of magnet breakage and increase in magnetic resistance and reduces torque ripple.

A preferred example of the present invention is a rotor having a rotor core, a permanent magnet arranged on the inner diameter side of the rotor core, and a stator core arranged on the inner diameter side of the rotor via a gap. The rotor core has a stator having a coil attached to the stator core, and the rotor core is an abduction type having a plurality of voids per pole on the outer diameter side of the surface to which the permanent magnet is attached. It is a surface magnet rotating electric machine.

According to the present invention, it is possible to reduce the demerits of magnet breakage and increase in magnetic resistance, and also to reduce torque ripple.

The figure which shows the radial cross section of the abduction type surface magnet rotary electric machine in Example 1. FIG. The figure which shows the radial cross section which enlarged the void in Example 1. FIG. The figure which shows the radial cross section which enlarged the void in Example 2. FIG. The figure which showed the torque ripple with respect to the number of voids in Example 2. FIG. The figure which shows the radial cross section which enlarged the void in Example 3. FIG. The figure which showed the torque ripple with respect to the void position in Example 3. FIG. The figure which shows the cross section in the axial direction in Example 4. FIG. The figure which shows the cross section in the axial direction of the elevator hoisting machine in Example 5.

Hereinafter, examples will be described with reference to the drawings.

FIG. 1 shows Example 1 of the abduction type surface magnet rotary electric machine of the present invention. FIG. 1 is a radial sectional view of an abduction type surface magnet rotating electric machine. The radial direction refers to the outer peripheral direction from the center of FIG. The abduction type surface magnet rotating electric machine 1 of the present embodiment is arranged with a predetermined gap on the inner diameter side of the rotor 4 composed of the rotor core 2 and the permanent magnet 3 and the stator core. A stator 7 composed of 5 and a coil 6 is provided.

Here, it is desirable that the permanent magnet 3 is a surface magnet type arranged on the surface of the rotor core 2. As a result, by arranging the permanent magnet 3 on the surface of the rotor core 2, the leakage magnetic flux in which the magnet magnetic flux is short-circuited in the rotor can be reduced, and the effective magnetic flux is increased, so that the output can be increased.

Further, it is desirable that the coil 6 is attached to the stator core 5 by centralized winding. As a result, the length of the axial end portion of the coil 6 is shortened, the axial length of the abduction type surface magnet rotating electric machine 1 is shortened, and the size can be reduced. Further, it is desirable that the portion (slot 8) in which the coil 6 of the stator core 5 is arranged is an open slot. This facilitates the insertion of the coil 6 and improves the assembleability.

Further, it is desirable that the radius of curvature near the gap side (tip of the tooth) of the stator core 5 has a radius smaller than the radius of the stator 7. As a result, the rate of change of the magnetic resistance in the circumferential direction can be reduced, and the torque ripple can be reduced.

Here, a gap 9 is provided on the outer diameter side of the mounting surface on which the permanent magnet 3 of the rotor core 2 is mounted. FIG. 2 shows an enlarged view of the vicinity of the gap 9. By providing the gap, the change in the magnetic resistance seen from the stator side is leveled, the harmonic component superimposed on the magnetic flux is reduced, and the torque ripple can be reduced. In FIG. 2, two voids 9 are arranged per magnet.

When there is only one gap 9, the gap may be enlarged in order to obtain a gap position where optimum torque ripple reduction can be obtained. Since the void 9 is a non-magnetic portion, it becomes a magnetic resistance when viewed from a magnet. As the number of voids increases, the magnetic resistance also increases and the electrical characteristics deteriorate. On the other hand, when two or more voids that do not contact each other are formed, the gap is a magnetic material and magnetic flux can pass through, so that deterioration of electrical characteristics can be reduced.

In addition, by using voids instead of dents and grooves, the shape of the magnet placement part becomes constant, so there is no need to change the manufacturing method, and the risk of magnet damage due to impact is the same as before, so this book is easy. The structure can be applied.

Although FIG. 1 shows an abduction type surface magnet rotary electric machine having 40 poles and 48 slots, the shape is not limited to this, and the same effect can be obtained with other slot combinations. Further, when the abduction type rotary electric machine rotates both times, it is desirable that the positions of the two gaps are symmetrical with respect to the central axis of the permanent magnet 3 as shown in FIG.

Further, the voids do not need to be filled with air and may be a non-magnetic material such as resin. Regarding the shape of the void, although it is a semicircular shape in FIG. 2, it may be circular, triangular, trapezoidal, or the like, and the shape is not limited. In addition, the size and shape of the gap need not be unified within one magnetic pole, and the size and shape of the gap may be changed for each magnetic pole. Further, one or more permanent magnets 3 may be arranged per pole, and may be arranged in the circumferential direction with a substantially constant space from the permanent magnets of adjacent magnetic poles.

According to the first embodiment, the gap 9 is arranged in the rotor core 2 on the outer diameter side of the mounting surface of the rotor core 2 to which the permanent magnet 3 is mounted, which affects the member holding the magnet. Without giving, the possibility of damaging the magnet can be reduced. Further, it is possible to reduce torque ripple while reducing the demerit of increasing magnetic resistance.

FIG. 3 is a diagram showing an abduction type surface magnet rotating electric machine according to a second embodiment. In Example 1, the number of voids per pole was considered to be two, but the number of voids may be two or more. FIG. 4 shows the sixth torque ripple with respect to the number of voids. The sixth torque ripple is a pulsation that is a multiple of 6 of the fundamental frequency.

As described above, the torque ripple reduction effect differs depending on the position of the gap. Therefore, the void position and size were defined by the same standard by the optimization method. From FIG. 4, it can be seen that by changing the number of voids from 2 to 4, the torque ripple is reduced and the effect of reducing the torque ripple is greatly increased.

However, even if the number of voids is set to 4 to 6, the effect of reducing torque ripple is small. Increasing the voids increases the number of processes and may increase the cost, so it is inappropriate to increase the number of voids. Therefore, the number of voids is preferably 4.

According to the second embodiment, by setting the number of voids per pole to 4, the effect of reducing torque ripple can be increased.

FIG. 5 is a diagram showing an abduction type surface magnet rotating electric machine of the third embodiment. In the second embodiment, the effect of reducing the sixth-order torque ripple was examined, but the effect of reducing the torque ripple due to the irregularity of the rotating electric machine is examined.

In the case of a 10-pole, 12-slot abduction type surface magnet rotating electric machine, secondary and 2.4th-order torque ripples are generated due to irregularities in the rotating electric machine. As shown in FIG. 5, the shortest distance between the central portion of the permanent magnet 3 and the gap is W1, and the shortest distance between the end of the permanent magnet 3 and the gap is W2.

FIG. 6 shows a comparison between torque ripple when W1> W2 and torque ripple when W1 <W2. When there are a plurality of voids, the largest void is targeted, and when there are a plurality of voids of the same size, the void closest to the center of the magnet is targeted.

As shown in FIG. 6, it can be seen that the effect of reducing torque ripple due to irregularity of the rotating electric machine is greater when W1 <W2. Therefore, in order to reduce torque ripple due to irregularity of the rotating electric machine, it is preferable that W1 <W2.

According to the third embodiment, the effect of reducing the torque ripple can be increased by adjusting the positional relationship between the permanent magnet and the void.

FIG. 7 is a diagram showing an abduction type surface magnet rotating electric machine of the fourth embodiment. FIG. 7 is a cross-sectional view in the axial direction, which is shown for 1/2 minute in the radial direction. It should be noted that the hatched portion in FIG. 7 shows that it is a rotating structure. The rotor 4 is arranged in the rotor frame 10, and the stator 7 is arranged in the stator frame 11.

The rotor frame 10 is connected to the shaft 12 and is connected to the stator frame 11 via a bearing 13. The axial direction is the longitudinal direction of the shaft 12. Here, an auxiliary bearing 14 may be provided to hold the shaft.

A high thermal conductive member 15 such as a heat pipe is arranged in the gaps shown in Examples 1 to 3 and extends to the outside of the rotor 4 of the high thermal conductive member 15. The operating temperature of permanent magnets is limited, and the performance deteriorates due to irreversible demagnetization at high temperatures. Moreover, the temperature of the permanent magnet is not constant and has a distribution in the axial direction.

Therefore, it is desirable that the magnet temperature is uniform because only the portion having the highest temperature of the permanent magnet may be irreversibly demagnetized.

Therefore, according to the fourth embodiment, by providing the high thermal conductive member 15 in the void, the thermal resistance in the axial direction of the permanent magnet is lowered, and the magnet temperature can be made uniform.

Further, by attaching fins or the like to the ends of the high thermal conductive member 15, the heat dissipation area is increased, the heat transfer coefficient is improved by the peripheral speed due to rotation, and the magnet temperature can be effectively reduced.

Although the structure in which the shaft rotates is shown in FIG. 7, the same effect can be obtained even in a structure in which the shaft in which the bearing is connected between the rotor frame 10 and the shaft 12 does not rotate.

FIG. 8 is a diagram showing a sixth embodiment in which the abduction type surface magnet rotary electric machine of the fourth embodiment is applied to a hoisting machine for an elevator. Note that FIG. 8 shows only 1/2 of the radial cross section, and the rotating portion is hatched.

As shown in FIG. 8, an abduction type surface magnet rotating electric machine 1 is provided as a power for winding the rope 16 connected to the car, and a sheave 17 for winding the rope 16 for an elevator hoist and a brake 18 for mechanically stopping the rotation are provided. It is attached.

According to the fifth embodiment, since the torque pulsation of the abduction type surface magnet rotating electric machine is reduced, the riding comfort of the elevator can be improved.

1 ... Abduction type surface magnet rotary electric machine, 2 ... Rotor core, 3 ... Permanent magnet, 4 ... Rotor, 5 ... Stator core, 6 ... Coil, 7 ... Stator, 8 ... Slot, 9 ... Void, 10 ... Rotor frame, 11 ... Stator frame, 12 ... Shaft, 13 ... Bearing, 14 ... Auxiliary bearing, 15 ... High heat conductive member, 16 ... Rope, 17 ... Sheave, 18 ... Brake

Claims (12)

A rotor having a rotor core and a permanent magnet arranged on the inner diameter side of the rotor core,
It has a stator core arranged on the inner diameter side of the rotor via a gap, and a stator having a coil attached to the stator core.
The rotor core is an abduction type surface magnet rotating electric machine characterized by having a plurality of voids per pole on the outer diameter side of the surface to which the permanent magnet is attached. In the abduction type surface magnet rotating electric machine according to claim 1.
An abduction type surface magnet rotating electric machine, characterized in that one or more permanent magnets are arranged per pole and arranged in the circumferential direction with a substantially constant space with the permanent magnets of adjacent magnetic poles. In the abduction type surface magnet rotating electric machine according to claim 1.
An abduction type surface magnet rotating electric machine characterized in that the voids are not in contact with each other. In the abduction type surface magnet rotating electric machine according to claim 1.
An abduction type surface magnet rotating electric machine characterized in that the voids per pole are arranged symmetrically with respect to the center of the permanent magnet. In the abduction type surface magnet rotating electric machine according to claim 1.
An abduction type surface magnet rotating electric machine characterized in that the voids are filled with a non-magnetic material. In the abduction type surface magnet rotating electric machine according to claim 1.
An abduction type surface magnet rotating electric machine characterized in that the number of the voids per pole is four. In the abduction type surface magnet rotating electric machine according to claim 1.
An abduction type surface magnet rotating electric machine characterized in that W1 <W2 when the distance between the center of the permanent magnet and the void is W1 and the distance between the end of the permanent magnet and the void is W2. .. In the abduction type surface magnet rotating electric machine according to claim 1.
An abduction type surface magnet rotating electric machine characterized in that a high heat conductive member such as a heat pipe is arranged in the gap. An elevator hoisting machine including the abduction type surface magnet rotating electric machine according to claim 1 as a power for winding a rope connected to a car. In the abduction type surface magnet rotating electric machine according to claim 1.
An abduction type surface magnet rotating electric machine characterized in that the void has a semicircular, circular, or trapezoidal shape. In the abduction type surface magnet rotating electric machine according to claim 1.
An abduction type surface magnet rotating electric machine, characterized in that the radius of curvature of the stator core on the gap side is smaller than the radius of the stator. In the abduction type surface magnet rotating electric machine according to claim 1.
An abduction type surface magnet rotating electric machine characterized in that the coil is arranged in a slot of the stator core.

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