JPH10136595A - Magnet rotor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the torque and the efficiency of an electric motor, by reducing the radius of the arc surface at the outer periphery side of a magnet as compared from that of the arc surface of an insertion hole corresponding to the part after engaging the magnet. SOLUTION: The radius of the arc surface at the outer periphery side of a magnet 7 is reduced as compared with that of the arc surface of an insertion hole 2 corresponding to the arc surface, thus bringing the arc surface of the magnet into contact with the arc surface of the insertion hole 2 at a center part in peripheral direction and generating a gap 12 at the edge part in peripheral direction. With this configuration, the rate of a magnetic flux due to the magnet for flowing in and out through the area of a center part 11 in peripheral direction of a bridge part 10 increases and, at the same time, the amount of leakage decreases at the area between poles of the edge part in peripheral direction, and the magnetic flux density at this area decreases, thus creating a condition at a core part 9 between the magnets at a part between poles where a stator magnetic flux easily flows in and out, increasing q-axis inductance value and hence a protrusion pole ratio, and increasing reluctance torque due to the magnetic flux of a stator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adduction type rotor having a permanent magnet mounted thereon, such as a motor for driving a compressor of a refrigerator or an air conditioner, and more particularly, to a rotor in which a magnet is embedded inside an iron core. And a so-called IPM magnet rotor.

[0002]

2. Description of the Related Art In general, the above-mentioned rotor forms an iron core by laminating a large number of thin iron plates, and the iron core has a plurality of receiving holes for receiving magnets. Known examples are disclosed, for example, in Japanese Patent Application Laid-Open No. 5-176487.

This rotor is disposed in a stator having three-phase windings so as to face each other with a predetermined air gap therebetween, and constitutes a permanent magnet type synchronous motor. The excitation is performed to perform rotation. In the case of the IPM motor configured as described above, the reluctance torque generated due to the difference in the magnetic resistance depending on the rotor position,
Control driving is performed so as to use both of the main magnetic flux torque generated by the magnetic flux of the magnet interlinking with the stator winding.

That is, the direction connecting the center of the magnetic pole of the magnet of the rotor and the axis of rotation is defined as d-axis, and the electrical angle 90 with respect to this d-axis is assumed.
゜ Phase is q axis, magnetic flux amount by magnet is Φ, d axis current is Id, q axis current is Iq, d axis inductance is Ld, q
When the shaft inductance is Lq, the motor torque T
Is generally represented by the following equation. T = Φ · Iq + (Ld−Lq) Id · Iq (1)

[0005] The IPM motor exhibits a so-called reverse saliency with a relation of Ld <Lq, and a reluctance torque component is obtained instead of the main magnetic flux Φ being slightly reduced, and this reluctance torque is effectively utilized. Large torque and high efficiency can be achieved.

[0006]

In the above-described magnet rotor of the IPM, the shape of a plurality of receiving holes provided in the iron core is substantially similar to the cross-sectional shape of the magnet, and the magnet is inserted into the receiving hole by, for example, press-fitting. It is configured by being fitted. In this configuration, since the iron core portion is interposed between the poles of the magnets, the magnetic flux from the magnet leaks into the interpole portion, and the magnetic flux density in the iron core portion becomes extremely high. Therefore, a state in which the stator magnetic flux is difficult to flow in and out is formed in this portion. As a result, the value of the q-axis inductance is small, and the salient pole ratio Lq
/ Ld is reduced, so that an increase in motor efficiency due to an increase in reluctance torque cannot be expected.

Further, since the receiving hole and the magnet have similar shapes,
The contact area between the two exists over the entire circumference, so that a slight misalignment of one of them or the addition of both misalignments tends to cause poor fitting, making it impossible to insert the magnet into the accommodation hole, reducing the number of insertion steps. In many cases, it was necessary. In order to prevent this, increase the number of polishing of the punching die to maintain the accuracy of the punching dimensions of the iron core, increase the polishing cost to obtain the accuracy of the magnet dimensions, etc.
It was very costly.

[0008]

According to the present invention, an iron core is formed by laminating a large number of thin iron plates, and an accommodation hole for fitting a magnet is provided in the iron core. In a magnet rotor in which a portion to be disposed is formed by fitting a magnet having an arcuate surface, the radius of the arcuate surface on the outer peripheral side of the magnet is determined by the radius of the arcuate surface of the receiving hole corresponding to this portion after the magnet is inserted. Are also made smaller.

In addition, as a result of the above configuration, the outer circumferential surface of the magnet is in contact with the outer circumferential surface of the housing hole corresponding to this portion at the center in the circumferential direction. A central portion in the circumferential direction of the iron core bridge portion interposed between the outer peripheral arc surface of the accommodation hole is formed so as to be recessed from the outer diameter of the iron core before the magnet is fitted.

[0010]

By inserting the magnet, the arcuate surface on the outer peripheral side of the magnet and the arcuate surface on the outer peripheral side of the accommodation hole corresponding to this portion are brought into contact with each other at the center in the circumferential direction, and a gap is formed at the circumferential end. Becomes As a result, the ratio of the magnetic flux by the magnet passing near the central portion in the circumferential direction increases, and the amount of leakage near the gap between the circumferential ends decreases, so that the magnetic flux density in this portion decreases. Therefore, a state where the stator magnetic flux easily flows in and out of the core portion between the magnets in the pole portion is formed. As a result, the value of the q-axis inductance increases and the salient pole ratio Lq / Ld increases.

Further, as described above, since the magnet and the circular arc surface on the outer peripheral side of the housing hole abut at the central portion in the circumferential direction, when the outer peripheral portion of the bridge portion of the iron core swells due to this, when the outer peripheral portion of the bridge portion of the iron core protrudes, By bulging into the dent, it does not protrude more than a predetermined core outer diameter.

[0012]

An embodiment of the present invention will be described with reference to the drawings.
In the rotor shown in FIG. 1, reference numeral 1 denotes an iron core, which is a well-known caulking clamp means 6 for laminating a number of thin iron plates punched in a predetermined shape, cutting and raising the thin iron plates, and caulking them with projections.
Is formed by being fixed. An outer peripheral portion of the iron core 1 forms a surface facing the stator via an air gap, and a shaft hole 3 is provided at a central portion. A plurality of receiving holes 2 are provided annularly in the vicinity of the outer periphery, and a magnet 7 is fitted into each receiving hole 2 and one magnet is magnetized to form one pole to generate a field. Has formed. Reference numeral 4 denotes a caulking pin insertion hole. End plates are attached to both ends of the iron core 1 in the stacking direction by caulking pins 8 inserted into the insertion holes, thereby closing the accommodating hole 2 to seal the magnet 7 and, if necessary, a rotor. Attachment parts such as balance weights are attached to the ends.

[0013] The magnet 7 has a camber-like shape having an arcuate outer circumferential side and a linear cross-sectional shape on the inner circumferential side. This shape has a large thickness in the radial direction, and thus has excellent magnetic flux amount and demagnetization resistance. It has a shape. This magnet 7 is an iron core 1
Into the receiving hole 2 by a clearance fit.
It is fixed so that it is pressed from the inner peripheral side to the outer peripheral side in the accommodation hole and does not move easily.

FIG. 2 is an enlarged sectional view showing an essential part of the rotor of FIG. 1 in an exaggerated manner, and FIGS. 3 and 4 show the iron core 1 in FIG.
2 shows a state before the magnet 7 is assembled. Magnet 7
The radius R3 of the arc surface 17 on the outer peripheral side of the magnet is formed smaller than the radius R1 of the arc surface 16 of the accommodating hole 2 corresponding to the arc surface 17, and as a result, as shown in FIG. 17 and the arcuate surface 16 of the accommodation hole abut at the center in the circumferential direction, and a gap 12 is formed at the end in the circumferential direction.

With this configuration, the ratio of the magnetic flux generated by the magnet flowing out and in through the vicinity of the circumferential central portion 11 of the bridge portion 10 increases, and the amount of leakage decreases near the gap between the circumferential ends. As a result, the magnetic flux density in this portion becomes low. Therefore, a state where the stator magnetic flux easily flows in and out of the iron core portion 9 between the magnets in the inter-pole portion is formed. As a result, the value of the q-axis inductance increases and the salient pole ratio Lq
/ Ld increases. Therefore, the reluctance torque due to the stator magnetic flux increases.

On the other hand, as described above, only the circumferential center portion of the arc surface 17 of the magnet 7 is in contact with the arc surface 16 of the housing hole 2, so that the circumferential center portion 11 of the bridge portion 10 of the iron core is deformed. The outer peripheral portion of the iron core 1 swells, and the rotor comes into contact with the stator, or a run-out occurs, which may cause large vibration or noise during rotation. In order to cope with this, as shown in an enlarged view in FIG. 5, a central portion 11 of the bridge portion 10 has a predetermined core outer diameter 1 indicated by a broken line.
5 is provided in advance with a concave portion 13 formed by recessing
Even if this portion is deformed outward due to the insertion of the magnet, it does not protrude beyond the predetermined iron core outer diameter 15 formed by the radius R2, or its size does not increase even if it protrudes.

1 and 2, reference numeral 5 in FIG. 1 and FIG. 2 denotes an elongated hole provided in the vicinity of the inner peripheral side of the accommodation hole 2, and after the magnet 7 is inserted into the accommodation hole 2, The core portion 14 between the long hole 5 and the housing hole 2 is pressed in the laminating direction or the outer diameter direction to be plastically deformed radially outward, so that the radially outwardly swelled portion is pressed against the magnet 7. Thus, the magnet 7 is fixed in the housing hole 2. As another method, before the magnet 7 is inserted into the housing hole 2, the core portion 14 may be pressed to expand into the housing hole 2, and then the magnet 7 may be pressed into the housing hole 2. .

As is well known, magnets such as ferrite and neodymium-based rare earths have a large variation in finished dimensions, and therefore are formed by dimensional adjustment by polishing in the final step. In the case of a Kamaboko-shaped magnet as shown in FIG.
First, the inner peripheral straight part is polished, and then the outer circular arc is polished based on this linear part. Has to be allowed. Further, since the receiving hole provided in the iron core is formed by punching out with a press die, a dimensional variation of about ± 0.05 mm also occurs in this case.

Therefore, in the present invention, the radius R3 of the circular arc surface on the outer peripheral side of the magnet 7 and the radius R1 of the circular arc surface on the outer peripheral side of the housing hole 2 have the above-mentioned dimensional variations.
For this reason, in setting the actual dimensions, if the upper limit dimension value of the tolerance of R3 in the polishing process is set to be smaller than the lower limit dimension value of the tolerance of R1 in the punching,
The desired shape of the present invention can be reliably obtained.

As a feature of the present invention, since the arc surface 17 of the magnet 7 and the arc surface 16 of the housing hole 2 are locally abutted as described above, the interference of the abutting portion is somewhat large. Even if it does, there will be no trouble in press-fitting the magnet into the housing hole. Therefore, the punching dimensions of the iron core 1 and the magnet 7
The tolerances for one or both of the polishing dimensions of these do not require very tight control.

FIG. 6 shows another embodiment of the present invention, and shows an example of a rotor using a C-shaped magnet 7a in which both the outer peripheral side and the inner peripheral side are formed in an arc shape. Also in the case of the rotor of FIG. 6, the radius of the arc surface on the outer peripheral side of the magnet 7a is formed smaller than the radius of the arc surface on the outer peripheral side of the accommodation hole 2a of the iron core 1a corresponding to this arc surface. . The other parts are the same as those of the rotor of FIG. 1, and the same or corresponding parts as those shown in FIG. 1 are denoted by the same reference numerals, and the description of the overlapping parts will be omitted.

[0022]

According to the present invention, the q-axis inductance is increased, and the salient pole ratio Lq / Ld is increased. As a result, the reluctance torque is increased, and a higher torque and higher efficiency of the motor are achieved. is there.

Further, since the magnet and the arcuate surface on the outer peripheral side of the accommodation hole are locally brought into contact with each other, it is easy to insert the magnet, and it is not necessary to strictly control the polishing size of the magnet and the punching size of the iron core. Cost can be significantly reduced. Further, by forming the central portion in the circumferential direction of the iron core bridge portion so as to be depressed from the outer diameter of the iron core, even when the core bridge portion is deformed by the insertion of the magnet, the predetermined outer diameter of the iron core is substantially equal. The effect is maintained that the contact with the stator and the generation of vibration and noise can be prevented.

[Brief description of the drawings]

FIG. 1 is a plan sectional view of a rotor showing an embodiment of the present invention.

FIG. 2 is an enlarged view showing an essential part of FIG. 1 in an exaggerated manner.

FIG. 3 is a sectional view showing an iron core before assembly in the rotor of FIG. 2;

FIG. 4 is a sectional view showing a magnet before assembly in the rotor of FIG. 2;

FIG. 5 is an enlarged view of a main part of FIG. 3;

FIG. 6 is a plan sectional view of a rotor showing another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 1a Iron core 2, 2a Housing hole 3 Shaft hole 6 Caulking clamp means 7, 7a Magnet 8 Caulking pin 9 Core part between magnets 10 Bridge part 13 Recess

Claims (2)

[Claims] 1. An iron core formed by laminating a number of thin iron plates,
In the magnet rotor provided with a receiving hole for fitting a magnet in the iron core, the receiving hole is configured by fitting at least a magnet formed in an arc surface at a portion arranged on the outer peripheral side,
A magnet rotor, wherein the radius of the arc surface on the outer peripheral side of the magnet is smaller than the radius of the arc surface of the accommodation hole corresponding to this portion after the magnet is inserted. 2. A central portion in a circumferential direction of a core bridge portion interposed between an outer peripheral portion of the iron core and an outer peripheral arc surface of the accommodation hole is recessed from an outer diameter of the iron core before the magnet is fitted. The magnet rotor according to claim 1, wherein the magnet rotor is formed.