JPH11285184A - Permanent-magnet motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance motor efficiency by making effective use of magnet torque and reluctance torque, in a permanent-magnet motor. SOLUTION: In an inner rotor-type permanent-magnet motor, permanent magnets 11 in a number equivalent to the number of poles concerned are embedded in the rim of a core at equal intervals, and the permanent magnets 11 are so formed that their cross-sectional shape is of convex lens. Flux barriers are formed at both the ends of the permanent-magnets 11, and the permanent magnets 11 are formed such that their faces on one side are located along the rim of the rotor core 10, and their faces on the other side are of a shape with the distance from the center hole 4 take into account. The distance between the adjacent permanent magnets 11 in different poles is set to a value not less than the thickness of one electromagnetic steel plate used for the rotor core 10 to ensure magnetic path from the stator core 1. Caulking pins 12 are inserted and caulking areas 13 are formed in the region between the permanent magnets 11 and the center hole 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inner rotor type permanent magnet electric motor used for an air conditioner, a compressor of a refrigerator, and the like, and more particularly, to an effective use of reluctance torque by a shape of a permanent magnet for obtaining a magnet torque. The present invention relates to a permanent magnet motor that can be used.

[0002]

2. Description of the Related Art An inner rotor of this type of permanent magnet motor has a structure in which permanent magnets are embedded in a rotor core.

As shown in FIG. 5, a plate-shaped permanent magnet 3 is provided on a rotor core 2 in a 24-slot stator core 1 by the number of poles (four poles) of the permanent magnet motor along an outer diameter in a circumferential direction. Buried in In addition, 4 is a center hole (hole for a shaft), 5 is a caulking pin, and 6 is a swaged portion.

In this case, since the shape of the permanent magnet 3 is substantially fan-shaped in cross section, the outer arc of the fan is formed along the outer periphery of the core, and the inner arc of the fan is formed as a straight line. (Magnet amount) is large, and a large magnet torque can be obtained. In addition, since the inside of the fan shape is a straight line, a square boss is formed at the center of the core. The caulking pin 5 can be passed through the boss, and the caulked portion 6 can be formed. There is also a distance from the center hole 4, which is preferable from the viewpoint of core strength.

[0005]

However, the above-mentioned permanent magnet motor has a drawback that reluctance torque cannot be used and motor efficiency cannot be improved. That is, in order to increase the usage of the permanent magnets 3, the space between the adjacent permanent magnets 3 is narrow, and the width (thickness) of the permanent magnets 3 is increased, so that the magnetic flux from the stator core 1 is increased. This is because it is difficult to secure the road.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object thereof is to change a sectional shape of a permanent magnet to effectively use a magnet torque and a reluctance torque, and to improve motor efficiency. It is an object of the present invention to provide a permanent magnet motor as described above.

[0007]

In order to achieve the above object, the present invention relates to a permanent magnet electric motor having a rotor core therein, wherein permanent magnets corresponding to the number of poles are embedded in the rotor core at equal intervals along the outer periphery of the core. In addition, the cross-sectional shape of the permanent magnet is a convex lens shape.

[0008] In this case, it is preferable that the adjacent permanent magnets to be buried have different polarities, and the interval between the permanent magnets having different polarities is equal to or greater than the thickness of one electromagnetic steel sheet used for the rotor core.

One surface of the permanent magnet is a curve along the outer periphery of the core, and the other surface is a curve having a predetermined distance between the midpoint of the arc and the center hole. It is preferable to form a flux barrier by chamfering.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to FIGS. In the figure,
The same parts as those in FIG. 5 are denoted by the same reference numerals, and redundant description will be omitted.

According to the permanent magnet motor of the present invention, if the permanent magnet embedded in the rotor core has a convex lens cross section, the amount of the permanent magnet used (magnet amount) can be increased, that is, the magnet torque can be improved. In addition, attention is paid to the fact that a path for the magnetic flux from the stator core can be secured, that is, the use of reluctance torque can be expected.

Therefore, as shown in FIGS. 1 and 2,
In the rotor core 10 of the permanent magnet motor, permanent magnets 11 having a convex lens cross section are embedded at equal intervals along the outer periphery of the core by the number of poles (quadrupoles). Each permanent magnet 11 has one surface along the outer periphery of the core and the other surface facing the center hole 4.

Further, as shown in FIG. 3, a predetermined width s is provided between adjacent permanent magnets 11 having different polarities in order to secure a path for the magnetic flux from the stator core 1.
It is preferable that the thickness be equal to or more than the thickness of one electromagnetic steel sheet used for the zero. Note that the other surface of the permanent magnet 11 (the surface facing the center hole 4) may be a curve along a magnetic path (so-called magnetic flux path) from the stator core 1.

Therefore, in FIG. 1, the permanent magnet 11 is interposed in the path of the magnetic flux from the stator core 1 with respect to the q axis, and the path of the magnetic flux from the stator core 1 is arranged along the curve with respect to the d axis. Will be formed. That is, the difference between the q-axis inductance and the d-axis inductance increases, and the generation of reluctance torque can be expected.

Since each of the permanent magnets 11 has a convex lens shape in cross section, a certain area is formed between each of the permanent magnets 11 and the center hole 4, and a caulking pin 12 is passed through this area to form a caulking portion 13. To form

Further, as shown in FIG.
It is preferable to form flux barrier holes 11a on both end sides of 1. In this case, both ends of each permanent magnet 11 may be cut. This flux barrier hole 11a is
Since the short circuit and the leakage of the magnetic flux are prevented, the loss of the magnetic flux of the permanent magnet 11 is suppressed, and the decrease of the magnet torque is suppressed.

In the manufacture of the rotor core 10, a core laminating method (automatic laminating method) in which an electromagnetic steel sheet is punched out by an automatic press using a core press die and caulked in the die to integrally form the rotor core 10. adopt.

In the pressing process, the core sheet 10
When punching a, the hole of the permanent magnet 11 and the hole of the caulking pin 12 are punched, and the caulked portion 13 is formed for each lamination of the core sheet 10a. Therefore, the press working by the conventional automatic lamination method can be used as it is.

After the pressed and laminated cores are automatically caulked in this way, a magnet (for example, a ferrite magnet) is buried in the hole of the permanent magnet 11 and the lid is closed.
The permanent magnet 11 is magnetized and magnetized in the thickness direction of the convex lens shape.

FIG. 4 will be additionally described.
Three-phase (U-phase, V-phase and W-phase) armature windings are applied to the four-slot stator core 1, but the number of slots and the armature windings may be different. Further, in the stator core 1, for example, the outer diameter winding may be a U phase, the inner diameter winding may be a W phase, and an intermediate winding may be a V phase.

As described above, since the cross section of each permanent magnet 11 is formed into a convex lens shape, the amount of the permanent magnet 11 used is at least unchanged from the conventional one, that is, the magnet torque does not decrease, and the amount of the used magnet depends on the shape of the convex lens. Can be increased, and the flux barrier holes 11a can prevent short-circuit and leakage of magnetic flux.

Further, since the space between the adjacent permanent magnets 11 is predetermined and the cross section of the permanent magnets 11 has a convex lens shape, a sufficient magnetic path from the stator core 1 can be ensured, and the reluctance torque can be reduced. The occurrence can be expected. That is, the difference (Lq-Ld) between the q-axis inductance and the d-axis inductance becomes large, whereby reluctance torque can be generated. Therefore, the magnet torque and the reluctance torque can be effectively used, and the motor efficiency can be improved.

The other surface of the permanent magnet 11 (the center hole 4)
The permanent magnet 11 and the center hole 4
It is good to decide it in consideration of the distance to. As a result, the core strength does not need to be reduced, and the reliability can be prevented from lowering. In addition, if the rotor core formed as described above is incorporated into a DC brushless motor and used as a compressor motor of an air conditioner, the performance of the air conditioner can be improved without increasing costs (increase in operating efficiency,
Vibration and noise).

[0024]

As described above, according to the first aspect of the present invention, in the permanent magnet motor having the rotor core therein, the permanent magnets corresponding to the number of poles are provided on the rotor core along the outer periphery of the core. Since the permanent magnets are buried at equal intervals and the cross-sectional shape of the permanent magnet is a convex lens shape, the cross-sectional area of the permanent magnet (the amount of magnet used) can be at least approximately the same as that of the related art. In addition, since the center hole side of the permanent magnet is curved, the path of the magnetic flux from the stator core can be secured and reluctance torque can be generated, so that the magnet torque and the reluctance torque can be effectively used. There is an effect that the motor efficiency can be improved.

According to a second aspect of the present invention, in the first aspect, adjacent poles of the embedded permanent magnets have different polarities,
Since the interval between the permanent magnets having different polarities is set to be equal to or greater than the thickness of one electromagnetic steel sheet used for the rotor core, in addition to the effect of the first aspect, the path of the magnetic flux from the stator core is further secured. That is, since it is possible to reduce the magnetic resistance and to expect the generation of a larger reluctance torque, there is an effect that the motor efficiency can be improved.

According to the third aspect of the present invention, one surface of the permanent magnet according to the first or second aspect is a curve along the outer periphery of the core, and the other surface is a predetermined distance between the midpoint of the arc and the center hole. 3. Since the flux barrier is formed by forming a curve with a value and chamfering both end portions of the permanent magnet, in addition to the effect of claim 1 or 2, the amount of the permanent magnet used (magnet Amount) can be maximized, the short circuit and leakage of the magnetic flux of the permanent magnet can be prevented, and the generation of a larger magnet torque can be expected, so that the effect of improving the motor efficiency can be achieved. is there.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of a permanent magnet motor showing one embodiment of the present invention.

FIG. 2 is a schematic sectional view for explaining the rotor core shown in FIG. 1;

FIG. 3 is a schematic partial plan view for explaining the rotor core shown in FIG. 1;

FIG. 4 is a schematic partial plan view of a rotor core showing a modified embodiment of the present invention.

FIG. 5 is a schematic side view of a conventional permanent magnet motor.

[Description of Signs] 1 Stator core 4 Center hole (for shaft) 10 Rotor core (magnet embedded magnetic field core) 10a Core sheet 11 Permanent magnet (convex lens shape in cross section) 11a Hole (for flux barrier) 12 Caulking pin 13 Caulking portion

Claims (3)

[Claims] 1. A permanent magnet motor having a rotor core therein, wherein permanent magnets corresponding to the number of poles are embedded at equal intervals along the outer periphery of the core in the rotor core, and the cross-sectional shape of the permanent magnet is formed into a convex lens shape. A permanent magnet motor. 2. The permanent magnet electric motor according to claim 1, wherein adjacent permanent magnets to be buried have different polarities, and the distance between the permanent magnets having different polarities is equal to or greater than the thickness of one electromagnetic steel sheet used for the rotor core. . 3. One end of the permanent magnet is a curved line along the outer periphery of the core, and the other surface is a curved line having a predetermined distance between the midpoint of the arc and the center hole. 3. The permanent magnet motor according to claim 1, wherein a flux barrier is formed by chamfering a side.