JP2001320859A - Rotor of motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor wherein a mixed gas of coolant gas and lubricant is stirred in the upper part of the casing of a closed electric compressor to prevent the lubricant from being stagnant in the upper part of the casing. SOLUTION: Both the ends of a plate-like horseshoe-shaped balance weight attached to the end of a permanent-magnet rotor for the purpose of balance correction are joined to each other by an annular cross-linking portion larger than a rotor shaft hole. One or more of the plate-like horseshoe-shaped balance weights are laminated at the end of the permanent magnet rotor. Thus, the lubricant is prevented from being stagnant in the upper part of the casing of the closed electric compressor and let to return to the sump located at the bottom of the casing, and seizure in the interior of the compressor is prevented to avoid damage to the compressor assembly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor for an electric motor, and more particularly to a permanent magnet rotor suitable for a hermetic electric compressor and the like.

[0002]

2. Description of the Related Art Generally, a rotor of a hermetic electric compressor is corrected by attaching a balance weight to an end of a permanent magnet rotor in order to correct an imbalance generated in a compressor section. As a conventional method of correcting the balance of the permanent magnet rotor, a balance weight integrally formed by die casting is attached. When the balance required for the hermetic electric compressor is small, the compressor is formed of a metal such as aluminum, which has a low specific gravity and is relatively easy to perform injection molding. When the balance amount is large, it is formed of a metal such as zinc having a high specific gravity.

[0003] In the hermetic electric compressor, the amount of imbalance changes depending on the difference in compression capacity. Therefore, the amount of imbalance corrected at the rotor end of the motor also differs. Therefore,
The size of the balance weight attached to the rotor is changed according to the compression capacity.

A conventional example will be described with reference to the drawings. FIG.
1 shows a front sectional view of a hermetic electric compressor. The outer diameter of the stator core 1 is covered by a casing 7, and the interior of the stator core 1 is a hermetic electric compressor having a permanent magnet rotor 19. A permanent magnet 20 is mounted inside the rotor core 2, and a shaft 5 connecting to the compressor unit 6 is fixed to the rotor shaft hole 13 by press fitting or shrink fitting. The shaft 5 compresses the refrigerant gas in the compressor unit 6 by rotating the permanent magnet rotor 19. At both ends of the permanent magnet rotor 19, balance weights 3 and 4 for correcting the unbalance amount of the compressor section 6 are attached. An oil reservoir 1 for lubricating oil is provided at the bottom of the casing 7.
When the permanent magnet rotor 19 is driven to rotate, the refrigerant gas in the casing 7 and the mixed gas of the lubricating oil are wound up by centrifugal force and the windings 17 and the permanent magnets that jump out of the stator end at the upper part of the casing 7 After colliding with the magnet rotor 19 and the like, only lubricating oil is used for the stator core cut portion and the stator core 1
And the air returns to the oil sump 18 through the air gap portion and the like of the permanent magnet rotor 19. The refrigerant gas is discharged outside from a discharge pipe 8 provided beside the casing 7.

[0005] In the case of a scroll compressor or the like generally known as a hermetic electric compressor, a compressor section 6 is used.
, The balance weights 3 and 4 attached to the rotor also become large.

[0006]

With a balance weight attached to the end of a permanent magnet rotor and integrally formed by die-casting, the product has a very large thermal shrinkage during die-casting and large variations in product dimensions. Therefore, the balance weight is not stable. Also, since there are many nests or bubbles in the die-cast product, this is also a factor that increases the variation in the balance weight. In order to solve this problem, fine adjustments are made to the balance weight by drilling or the like to obtain a stable product.

When the required balance amount is small, it is formed of a metal such as aluminum, which has a low specific gravity and is relatively easy to be injection-molded.
In addition to cavities and bubbles as described above, mold burrs and the like are generated, and deburring work in post-processing is required. Also,
When the balance amount is large, it is molded with a metal such as zinc having a high specific gravity. However, similarly to aluminum, there is a problem that plastic deformation at high temperature is fast, in addition to problems such as nests, bubbles, and mold burrs. The inside of the hermetic electric compressor in which the permanent magnet rotor to which this balance weight is attached is built becomes extremely hot, and the permanent magnet rotor rotates at high speed, and centrifugal force is directly applied to the balance weight portion. There is a risk that the plastic weight starts to be formed earlier than aluminum and the balance weight contacts the inner diameter of the stator. Therefore, there is a need to restrict the use in the hermetic electric compressor.

[0008] Further, in the hermetic electric compressor, the amount of imbalance changes due to the difference in compression capacity, so that the amount of imbalance generated at the end of the permanent magnet rotor of the motor also changes. Accordingly, a balance weight mold for the permanent magnet rotor has to be manufactured for each specification of the compression capacity, so that the manufacturing cost of the mold is high.

Further, in the hermetic electric compressor, the refrigerant gas and the mixed gas of the lubricating oil in the casing are wound up by the centrifugal force of the permanent magnet rotor or the like and reach the upper portion of the casing, and return to the oil sump in the lower portion of the casing. However, when the balance weight of the balance weight attached to the end of the permanent magnet rotor is large, the balance height is inevitably increased, so that the refrigerant gas and the mixed gas of the lubricating oil, Stirred by this balance weight,
After the lubricating oil stagnates at the upper portion of the casing without returning to the oil sump at the bottom of the casing, the mixed gas is discharged from the discharge pipe, so that the amount of lubricating oil in the compressor is reduced and the inside of the compressor is seized. As a result, the hermetic electric compressor is broken. Further, when the mixed gas is discharged from the discharge pipe, the heat exchange efficiency of the heat exchange system deteriorates. In particular, when the hermetic electric compressor is the scroll compressor described above, since the amount of unbalance is very large, the height of the balance weight attached to the rotor also increases,
This tendency appears remarkably.

The axial opening of the rotor core is covered with an end plate or the like in order to prevent the magnet powder or chips of the permanent magnet mounted on the permanent magnet rotor from scattering outside the rotor. Further, in the surface-attached type, the surface of the permanent magnet is covered with a non-magnetic protective cover or the like. In the permanent magnet rotor embedded type, a permanent magnet is embedded inside the rotor core, and the rotor surface is covered with the iron core. For this reason, the magnetized position of the permanent magnet mounted inside the rotor cannot be confirmed visually, making the magnetization of the permanent magnet rotor extremely difficult. Therefore, if the magnet is erroneously magnetized, the magnet will be magnetized at a position different from the original magnetic pole position of the permanent magnet, and problems such as deterioration in performance of the electric motor, sound, and vibration occur.

The number of slots of the stator of the motor is 3N.
(N is a natural number), and when the stator teeth are wound by concentrated winding or the like, the height of the winding can be reduced as compared with the conventional distributed winding. loss,
That is, copper loss can be reduced. As a result, it is possible to reduce the protruding portion of the winding from the end of the stator, thereby reducing the overall length of the stator. However, as described above, the height of the balance weights attached to both ends of the 2N (N is a natural number) permanent magnet rotor needs to be very high. The overall length of the compressor could not be reduced and the hermetic motor compressor could not be lowered.

[0012]

Means for Solving the Problems A plate-shaped horseshoe-shaped balance weight for correcting the balance is provided at the end of the permanent magnet type rotor, and the plate-shaped horseshoe-shaped balance weight is formed by a shaft hole of the permanent magnet rotor. With a large ring-shaped bridge,
The plate-shaped horseshoe-shaped balance weight is formed by connecting both ends thereof. At least one plate-shaped horseshoe-shaped balance weight is laminated on the end of the permanent magnet rotor, thereby forming the upper part of the casing of the hermetic electric compressor. Thus, the mixed gas of the refrigerant gas and the lubricating oil can be stirred, and the lubricating oil can be returned to the oil sump at the bottom of the casing without stagnation at the upper portion of the casing. In addition, a stable balance weight can be obtained by using a plate-shaped horseshoe-shaped balance weight having a high specific gravity.

In order to magnetize the permanent magnet mounted on the permanent magnet type rotor, a positioning mark is provided on a plate-shaped horseshoe-shaped balance weight connected by a ring-shaped bridge portion larger than the shaft hole. Magnetization can be easily performed by adjusting the distance between the poles of the stator to the positioning mark.

The number of slots of the stator is 3N (N is a natural number), and the stator teeth are wound by concentrated winding or the like, and the magnetic poles are 2N (N is a natural number).
In the pole permanent magnet rotor, the overall length of the motor can be reduced by providing a plate-shaped horseshoe-shaped balance weight connected by a ring-shaped bridge portion larger than the shaft hole,
The overall length of the hermetic electric compressor can also be reduced.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a mounting diagram of a balance weight when the permanent magnet rotor of the present invention is viewed from the axial direction. FIG. 2 is a perspective view of the permanent magnet rotor shown in FIG. 1, and therefore the description of the drawing is shared with the description of FIG.
FIG. 1 or FIG. 2 shows a known embedded permanent magnet rotor in which a permanent magnet is embedded in a permanent magnet receiving hole provided in a laminated rotor core 2.

In the first embodiment, the rotor cores 2 are equally distributed in the radial direction at 90 ° so as to be three-phase and four-pole.
The permanent magnets are equally inserted into the respective permanent magnet receiving holes. End plates 1 are provided at both ends of the rotor core 2 in the axial direction.
0 is attached. The end plate 10 is provided with a clamp pin hole at the same position as the horseshoe-shaped balance weight 3a and the rotor core 2, and by inserting the clamp pin 9 into the clamp pin hole, the rotor into which the permanent magnet is inserted is inserted. Iron core 2, end plate 10, horseshoe-shaped balance weight 3a
Are fixed together. It is preferable to select a non-magnetic material as the material of the end plate 10. Also, the clamp pin 9
As the material of the magnetic material, a magnetic material or a non-magnetic material is appropriately selected and used depending on a position where the change in the magnetic flux is small and the characteristics of the motor are not deteriorated, a position where the influence of the mechanical stress is hardly affected, and the like. Also,
The method of forming the permanent magnet rotor is not limited to the above-mentioned method, and includes a method in which a permanent magnet is attached to the outer periphery of the rotor core 2 and the surface of the permanent magnet is covered with a protective cover made of a nonmagnetic material or the like.

The balance weight 3a of the first embodiment is
Because it is a plate-shaped horseshoe-shaped balance weight made of brass, stainless steel, or iron, etc., it differs from the balance weight that is integrally formed by die-casting of aluminum or zinc. As a result, variations in the balance weight are reduced, and no mold flash is generated at the time of injection molding of die casting, so that a stable product can be obtained.

In addition, since the product is stabilized, it is not necessary to make fine adjustments such as sharpening of the balance weight in a post-process. Further, since the inside of the hermetic motor compressor is at a high temperature, plastic deformation of the balance weight portion does not occur due to the influence of centrifugal force during high-speed rotation. In addition, since there is no need to manufacture a balance weight type for the permanent magnet rotor due to the difference in compression capacity of the hermetic electric compressor, when adjusting the balance amount, the thickness of the balance weight,
By stacking a plurality of plate-shaped balance weights, the balance weight can be adjusted. Therefore, it is possible to share the balance weight type, and it is not necessary to spend a mold cost. As the balance weight type, there is a method in which one sheet is punched one by one manually, or a known auto clamp type in which a plurality of sheets are stacked at a time and integrally crimped. The latter can simplify the manual laminating operation.

If the balance weight of the balance weight 3a attached to the end of the permanent magnet rotor is very large and the balance height is high, the rotor connecting the end portions 21 of the horseshoe-shaped balance weight 3a as in the first embodiment is used. By providing the wall of the ring-shaped bridging portion 11 larger than the shaft hole 13, the mixed gas of the refrigerant gas and the lubricating oil is wound up by the centrifugal force of the permanent magnet rotor or the like, and at the upper part of the casing of the hermetic electric compressor,
The mixing gas does not stir and stay at the upper portion of the casing. Accordingly, the mixed gas is not discharged from the discharge pipe, and the lubricating oil can be returned to the oil sump at the bottom of the casing, so that seizure inside the compressor can be prevented and the hermetic electric compressor is broken. No more. Further, since the mixed gas is not discharged from the discharge pipe, the heat exchange efficiency of the heat exchange system does not deteriorate.

Further, in the second embodiment, as shown in FIGS. 1 and 2, even if the arrangement of the permanent magnet mounted inside the permanent magnet rotor is not known, the horseshoe-shaped balance weight 3a is Positioning mark 12 for magnetizing
, The permanent magnet rotor can be easily and accurately magnetized. Therefore, since the magnet is not erroneously magnetized at a position different from the original magnetic pole position of the rotor, problems such as performance degradation, sound, and vibration of the electric motor do not occur. In addition, this positioning mark 12 is
It is not limited to the notch-shaped one shown in FIGS. 1 and 2, but may be provided with a horseshoe-shaped balance weight having a surface protruding in a convex shape, a concave indentation, or a groove shape. It is sufficient if the magnetized position of the permanent magnet rotor can be known when magnetizing is performed.

[0002] In a third embodiment, as shown in FIG.
The laminated stator core 1 has 3N (N is a natural number) slots. The stator teeth are provided with concentrated three-phase windings 16, and the stator has 2N poles inside. With a permanent magnet rotor. The insulation of each slot of the stator is made by a molded insulation 15 or the like, and a concentrated winding system manufactured by directly winding a winding 16 thereon. Since the winding height of the concentrated winding 16 applied to the stator can be made lower than the height of the conventional distributed winding 17 shown by a dotted line, copper loss, which is a loss due to the winding, can be reduced. Can be reduced. Therefore, by making the winding 16 of concentrated winding, the protruding portion from the end of the stator core 1 can be reduced, and the overall length of the stator can be reduced. However, in comparison with this, the conventional permanent magnet rotor has a problem of specific gravity of a die-cast product because the conventional balance weights 3 and 4 are formed by die-casting as shown by the dashed line in FIG. Because the height of the balance weights 3 and 4 is high, the total length of the permanent magnet rotor cannot be reduced even though the total length of the stator is low, and the total length of the motor cannot be reduced. . As in the third embodiment of the present invention, the height of the balance weight can be reduced by laminating the plate-shaped horseshoe-shaped balance weight 3a having a high specific gravity, that is, using the permanent magnet rotor of the present invention. Thus, the overall length of the motor can be reduced. Further, since the overall length of the hermetic electric compressor can be further reduced, the material of the hermetic electric compressor can be reduced. Also,
Since the plate-shaped horseshoe-shaped balance weight is stamped and laminated, nests, air bubbles, mold burrs, etc., which are conventionally generated, are eliminated, and the quality is improved. Also, the performance of the electric motor is improved, and the generation of noise and vibration is eliminated.

[0022]

The permanent magnet type rotor according to the present invention is provided with a plate-shaped horseshoe-shaped balance weight for correcting the balance at the end thereof, and the plate-shaped horseshoe-shaped balance weight has a ring shape larger than the rotor shaft hole. Both ends of the horseshoe-shaped balance weight are connected by a bridge portion, and at least one plate-shaped horseshoe-shaped balance weight is attached to the end of the permanent magnet rotor.
By laminating more than one, the mixed gas of the refrigerant gas and the lubricating oil is agitated at the upper part of the casing of the hermetic electric compressor and stagnated at the upper part of the casing, so that this mixed gas is not discharged from the discharge port and lubrication Since oil can be returned to the oil sump at the bottom of the casing, seizure inside the compressor is prevented, and the compressor is not broken. Also,
Since the mixed gas is not discharged from the discharge pipe, the heat exchange efficiency of the heat exchange system does not deteriorate.

When the permanent magnet rotor of the present invention is magnetized, the horseshoe-shaped balance weight is provided with a positioning mark to prevent the magnet from being erroneously magnetized. Motor performance degradation due to displacement, sound,
Problems such as vibration do not occur.

Further, the stator of the motor provided with the permanent magnet type rotor of the present invention has a slot number of 3N (N is a natural number), and the stator teeth are provided with windings such as concentrated winding. Further, by using a motor having a permanent magnet type rotor having 2N magnetic poles (N is a natural number), copper loss of the motor can be reduced, the efficiency of the motor can be increased, and the overall length of the motor can be reduced. Therefore, the overall length of the hermetic electric compressor can be reduced. Further, the present invention can be used for a hermetic electric compressor of a driving motor for an air conditioner or a refrigerator.

[Brief description of the drawings]

FIG. 1 is a view showing a first embodiment and a second embodiment of the present invention, in which a balance weight is attached when viewed from an axial direction of a permanent magnet rotor.

FIG. 2 is a perspective view of a permanent magnet rotor to which the balance weight of FIG. 1 is attached.

FIG. 3 is a front sectional view of an electric motor according to a third embodiment of the present invention.

FIG. 4 is a front partial sectional view of a conventional hermetic electric compressor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Stator core, 2 ... Rotor iron, 3, 3a, 4 ... Balance weight, 5 ... Shaft, 6 ... Compressor part, 7 ... Casing, 8 ... Discharge pipe, 9 ... Clamp pin, 10 ... End plate, 11
... Bridge section, 12 ... Positioning mark, 13 ... Shaft hole, 14 ...
Through-hole, 15: molded insulation, 16: winding, 17: winding, 1
8 ... oil pool, 19 ... permanent magnet rotor, 20 ... permanent magnet,
21 ... End.

Claims (3)

[Claims] An end portion of a permanent magnet type rotor is provided with a plate-shaped horseshoe-shaped balance weight for correcting the balance, and the plate-shaped horseshoe-shaped balance weight has a ring shape larger than a shaft hole of the permanent magnet rotor. By the bridge portion of the plate-shaped horseshoe-shaped balance weight is connected to both ends,
A permanent magnet type rotor, wherein at least one plate-shaped horseshoe-shaped balance weight is laminated on an end of the permanent magnet rotor. 2. The permanent magnet type rotating device according to claim 1, wherein a positioning mark is provided on the horseshoe-shaped balance weight for magnetizing the permanent magnet mounted on the permanent magnet type rotor. Child. 3. The stator of a motor having the permanent magnet type rotor has a slot number of 3N (N is a natural number), and the permanent magnet type rotor has a magnetic pole of 2N (N is a natural number).
The electric motor according to claim 1, wherein the electric motor is a pole.