JP5518026B2 - Rotor, electric motor equipped with the rotor, compressor equipped with the electric motor, refrigeration cycle apparatus equipped with the compressor, and air conditioner equipped with the refrigeration cycle apparatus - Google Patents

Description

  The present invention relates to a rotor, an electric motor including the rotor, a compressor including the electric motor, a refrigeration cycle apparatus including the compressor, and an air conditioner including the refrigeration cycle apparatus.

  In general, it is known that when a permanent magnet is exposed to a strong demagnetizing field in a high temperature state, the magnetization direction is reversed and demagnetization, that is, a phenomenon in which the magnetic force is weakened occurs.

  In a permanent magnet type motor with a permanent magnet built into the rotor core, the demagnetizing field applied to the permanent magnet increases as the stator winding current increases. When the winding current exceeds a certain value, it decreases rapidly. Magnetic susceptibility increases. This phenomenon is more likely to occur as the temperature of the permanent magnet increases.If irreversible demagnetization occurs in which the magnetic force does not recover even if the temperature of the permanent magnet is returned to room temperature after the demagnetization rate has once increased, the performance as a motor is reduced. It will deteriorate significantly. Hereinafter, the demagnetization caused by the temperature rise of the permanent magnet is referred to as “high temperature demagnetization”.

  Conventionally, in a surface magnet type motor (SPM motor: Surface Permanent Magnet Motor) having a structure in which a permanent magnet is attached to the outer peripheral surface of a rotor core, it is formed over the outer peripheral surface of the permanent magnet, that is, the surface facing the stator. A plurality of narrow grooves are provided at equal intervals in the rotation axis direction, and the surface area of the permanent magnets is increased by the grooves, thereby facilitating the cooling of the permanent magnets and suppressing the temperature rise of the permanent magnets. A technique for suppressing a decrease in magnetic properties of a magnet, that is, suppressing high temperature demagnetization of a permanent magnet is disclosed (for example, Patent Document 1).

JP 2001-074011 A

  However, the above prior art is a technique for a surface magnet type electric motor, and for a permanent magnet type electric motor including an interior permanent magnet motor (IPM motor) having a structure in which a permanent magnet is embedded in a rotor core. It is not a general-purpose technology. In addition, the fluid that should cool the permanent magnet flows in the axial direction on the surface of the permanent magnet. On the other hand, in the above-described prior art, since the groove is provided in the circumferential direction of the permanent magnet, a sufficient cooling effect cannot be obtained. There is a problem that the effect of suppressing the high temperature demagnetization of the permanent magnet is small.

  The present invention has been made in view of the above, and an object of the present invention is to provide a rotor capable of enhancing the effect of suppressing high temperature demagnetization of a permanent magnet embedded in a rotor core.

  In order to solve the above-described problems and achieve the object, the rotor according to the present invention is formed by laminating a plurality of electromagnetic steel plates in which a plurality of magnet insertion holes are provided at equiangular intervals along the circumferential outer periphery. A rotor iron core and a plurality of permanent magnets that are inserted alternately into the magnet insertion holes adjacent to each other to form magnetic poles, and the plurality of magnet insertion holes, when the permanent magnets are inserted, Grooves are formed in parallel to the axial direction so that a gap is formed at both ends in the circumferential direction of the magnet insertion hole, and the cross section of both ends in the circumferential direction exposed in the gap has a wavy uneven shape. And is used as a refrigerant flow path for the refrigerant to flow through the gap.

  According to the present invention, there is an effect that the effect of suppressing the high temperature demagnetization of the permanent magnet embedded in the rotor core can be enhanced.

FIG. 1 is a side view of a rotor according to an embodiment. FIG. 2 is a cross-sectional view of the rotor according to the embodiment. FIG. 3 is an enlarged view of a magnetic pole portion of the rotor according to the embodiment. FIG. 4 is a diagram illustrating one shape example of the end plate in the embodiment. FIG. 5 is a diagram in which the rotor according to the embodiment is viewed in the axial direction. FIG. 6 is a longitudinal sectional view of the compressor according to the embodiment. FIG. 7 is a diagram illustrating a configuration example of the refrigeration cycle apparatus according to the embodiment.

  Referring to the accompanying drawings below, a rotor according to an embodiment of the present invention, an electric motor including the rotor, a compressor including the electric motor, a refrigeration cycle apparatus including the compressor, and a refrigeration cycle apparatus thereof An air conditioner equipped with the above will be described. In addition, this invention is not limited by embodiment shown below.

Embodiment.
FIG. 1 is a side view of a rotor according to an embodiment. FIG. 2 is a cross-sectional view of the rotor according to the embodiment. In the present embodiment, a description will be given of an example applicable to an interior permanent magnet motor (IPM motor) having a structure in which a permanent magnet is embedded in a rotor core.

  As shown in FIG. 1 and FIG. 2, the rotor 1 according to the embodiment is formed by punching a thin plate (for example, about 0.1 to 1.0 mm) of electromagnetic steel sheet into a predetermined shape with a mold, and a predetermined number (multiple pieces). The shaft insertion hole 2a is provided at the center of the rotor core 3 formed by stacking, and the shaft 2 is inserted and fixed in the shaft insertion hole 2a. Further, in the axial direction on the outer peripheral side of the rotor core 3, a plurality of magnet insertion holes 6 are provided at equiangular intervals along the circumferential outer periphery, and adjacent permanent magnets are provided in the respective magnet insertion holes 6. 5 are inserted with alternating polarities. Further, the rotor core 3 is provided with a plurality of through holes 7 serving as main refrigerant flow paths in the axial direction inside the magnet insertion hole 6. The rotor 1 includes an end plate 4 that sandwiches the stator core 3 in the axial direction and fixes the permanent magnet 5 in the axial direction. The number, position, and shape of the through holes 7 may be other than those shown in FIG.

  FIG. 3 is an enlarged view of a magnetic pole portion of the rotor according to the embodiment. As shown in FIG. 3, the magnet insertion hole 6 is configured such that when the permanent magnet 5 is inserted, a gap 8 is formed in the circumferential direction both ends 6 a of the magnet insertion hole 6 as a refrigerant flow path in the same manner as the through hole 7. Is formed. In the present embodiment, this gap 8 is used as a refrigerant flow path for the refrigerant to flow therethrough. Thereby, the circumferential direction both ends 5a of the permanent magnet 5 are exposed to the space | gap 8, and it contacts a refrigerant | coolant directly. The permanent magnet 5 is cooled by allowing the low-temperature refrigerant to flow through the gap 8.

  Further, the circumferentially opposite end portions 5a of the permanent magnet 5 exposed in the gap 8 are formed with groove portions parallel to the axial direction so that the cross section has a wavy uneven shape. As a result, the surface areas of the circumferential end portions 5a of the permanent magnet 5 in contact with the refrigerant are increased, and the permanent magnet 5 can be cooled more efficiently without hindering the flow of the refrigerant. The effect of suppressing magnetism can be enhanced.

  FIG. 4 is a diagram illustrating one shape example of the end plate in the embodiment. FIG. 5 is a diagram in which the rotor according to the embodiment is viewed in the axial direction. As shown in FIGS. 4 and 5, the end plate 4 is processed into a shape that does not block the plurality of through holes 7 and the gaps 8 provided in the rotor core 3. 4 and 5, holes 10 are provided corresponding to the plurality of through holes 7 provided in the rotor core 3, and are located at positions around each magnetic pole portion including the circumferential end 5 a of the adjacent permanent magnet 5. The example which provided the notch 9 correspondingly is shown. 4 and 5, not only the notches 9 are provided, but the same number of holes having the same number as the gaps 8 may be provided corresponding to the positions of the gaps 8. In this way, even if the permanent magnet 5 is missing, it is possible to prevent the fragments from scattering.

  Next, the configuration of the compressor according to the present embodiment will be described. FIG. 6 is a longitudinal sectional view of the hermetic compressor according to the embodiment. As shown in FIG. 6, the compressor 11 according to the embodiment is driven by an electric motor 21 and an electric motor 21 inside a sealed container 19 having a bottomed cylindrical shape and an upper opening closed by a lid. A compression mechanism 20 is installed, and a refrigerating machine oil (not shown) for lubricating a sliding portion (not shown) of the compression mechanism 20 is mainly stored in the bottom of the sealed container 19.

  The electric motor 21 includes a stator 22 fixed to the upper part of the hermetic container 2 and a rotor 1 according to the embodiment in which the shaft 2 is inserted and fixed in the center, and is rotatably disposed on the inner peripheral surface of the stator 22. And.

  Next, the configuration and operation of the refrigeration cycle apparatus according to the present embodiment will be described. FIG. 7 is a diagram illustrating a configuration example of the refrigeration cycle apparatus according to the embodiment. Note that the refrigeration cycle apparatus according to the present embodiment shown in FIG. 7 is suitable for use in an air conditioner, for example.

  As shown in FIG. 7, the refrigeration cycle apparatus according to the embodiment includes a compressor 11, a condenser 12, a decompressor 13, an evaporator 14, a temperature sensor 15, and a bypass circuit (liquid injection circuit) 16 according to the embodiment. And a control circuit 25. The bypass circuit 16 is configured by connecting a pressure reducing device 17 and an on-off valve 18 in series between a liquid refrigerant discharge port of the condenser 12 and a gas suction port of the hermetic compressor 11. The temperature sensor 15 is provided in the vicinity of the gas discharge port of the compressor 11 and detects the temperature of the refrigerant flowing through the gas discharge port. The control circuit 25 controls the on-off valve 18 based on the detection result of the temperature sensor 15.

  First, the operation | movement at the time of the normal driving | operation of the refrigerating-cycle apparatus concerning embodiment is demonstrated with reference to FIG.2, FIG.3, FIG.6 and FIG. During normal operation of the refrigeration cycle apparatus, as shown in FIG. 6, a refrigeration cycle in which the refrigerant circulates in the order of the compressor 11, the condenser 12, the decompression device 13, and the evaporator 14 and returns to the compressor 11 again is performed.

  The high-temperature and high-pressure refrigerant gas compressed in the compressor 11 is condensed by exchanging heat with air in the condenser 12 to become a liquid refrigerant. The liquid refrigerant expands in the decompression device 13 to become a low-temperature and low-pressure refrigerant gas, evaporates by exchanging heat with air in the evaporator 14 and is compressed again in the compressor 11 to become a high-temperature and high-pressure refrigerant gas.

  Inside the compressor 11, the refrigerant gas flows along a path indicated by a dotted arrow in FIG. 6. The low-temperature and low-pressure refrigerant gas sucked from the gas suction port of the compressor 11 through the refrigerant suction pipe 23 is compressed by the compression mechanism 20 driven by the electric motor 21. The refrigerant gas that has become high temperature and pressure in this manner passes through the plurality of through holes 7 and the gaps 8 of the rotor core 3 described in FIGS. 2 and 3 and is discharged from the gas discharge port through the refrigerant discharge pipe 24. Is done.

  Next, an operation when the temperature of the refrigerant gas discharged from the gas discharge port of the compressor 11 abnormally rises due to some factor will be described with reference to FIGS. 2, 3, 6 and 7. In this case, the bypass circuit 16 bypasses the liquid refrigerant discharge port of the condenser 12 and the gas suction port of the compressor 11 and circulates the refrigerant along the path indicated by the solid line arrow in FIG. The liquid refrigerant is directly injected into the compressor 11. Thereby, the refrigerant temperature inside the compressor 11 rapidly decreases, and the refrigerant whose temperature has decreased passes through the plurality of through holes 7 and the gaps 8 of the rotor core 3. In the present embodiment, when the refrigerant whose temperature has decreased passes through the gap 8, it directly contacts the permanent magnet 5 exposed in the gap 8, so that the permanent magnet 5 can be efficiently cooled.

  More specifically, there is a correlation between the temperature of the permanent magnet 5 embedded in the rotor 1 and the temperature of the refrigerant gas detected by the temperature sensor 15 provided near the gas discharge port of the compressor 11. Therefore, a predetermined temperature lower than the upper limit temperature at which the permanent magnet 5 is not demagnetized at high temperature is set as a threshold in advance with respect to the temperature detected by the temperature sensor 15, and the temperature detected by the temperature sensor 15 is set to the predetermined threshold. What is necessary is just to make it the control circuit 25 control the on-off valve 18 so that it may not exceed. Alternatively, the opening / closing valve 18 may be controlled to open when the temperature of the refrigerant gas detected by the temperature sensor 15 exceeds the predetermined temperature described above.

  As described above, the rotor according to the embodiment, the electric motor including the rotor, the compressor including the electric motor, the refrigeration cycle apparatus including the compressor, and the air conditioner including the refrigeration cycle apparatus According to the present invention, when the permanent magnet is inserted into the magnet insertion hole, the magnet insertion hole is formed so that a gap is formed at both circumferential ends of the magnet insertion hole, and the refrigerant flow path for allowing the refrigerant to flow through the gap Since the refrigeration cycle apparatus is provided with a bypass circuit that bypasses between the liquid refrigerant discharge port of the condenser and the gas suction port of the compressor, when the temperature of the permanent magnet rises abnormally, By injecting low-temperature liquid refrigerant directly into the compressor, it passes through the gaps at both ends in the circumferential direction of the magnet insertion holes and directly contacts the surface of the permanent magnet exposed in the gaps. You It can, it is possible to enhance the effect of suppressing the high temperature demagnetization of the permanent magnet. Further, the present invention can be applied to an embedded magnet type electric motor (IPM motor: Interior Permanent Magnet Motor) having a structure in which a permanent magnet is embedded in a rotor core.

  In addition, since the grooves parallel to the axial direction are formed so that the cross-sections at both ends in the circumferential direction of the permanent magnet exposed in the air gap are wavy uneven, the surface area of the permanent magnet in contact with the refrigerant increases, The permanent magnet can be cooled more efficiently without hindering the flow.

  Also, a shape that is cut out corresponding to the position around each magnetic pole part including the circumferential end of the adjacent permanent magnet so as not to block the plurality of through holes and the gaps provided in the rotor core This prevents the permanent magnets embedded in the rotor core from moving in the axial direction without interfering with the flow of the refrigerant flowing through the through holes and gaps. can do.

  Alternatively, if permanent magnets are missing by providing holes in the end plate that have substantially the same shape as the through-holes and gaps corresponding to the positions of the multiple through-holes and gaps provided in the rotor core However, it is possible to prevent the fragments from scattering.

  Further, by increasing the effect of suppressing the high temperature demagnetization of the permanent magnet, it becomes possible to further increase the winding current of the stator, so that the output of the motor can be increased.

  In addition, in order to obtain an output equivalent to that of a conventional electric motor, it is possible to reduce the cost by adopting a permanent magnet having a smaller coercive force or designing a thinner permanent magnet.

  In the above-described embodiment, the detailed specifications such as the specific position, the cross-sectional shape, and the dimensions of the groove portions formed at both ends in the circumferential direction of the permanent magnet affect the performance of the motor, productivity, cost, It may be determined by comprehensively judging the strength and the like. In the example described with reference to FIG. 3, it has been described that grooves are formed at both ends in the circumferential direction of the permanent magnet exposed in the gap. However, grooves are formed in part or all of the circumferential ends of the permanent magnet exposed in the gap. May be. For example, the surface perpendicular to the magnetic field of the permanent magnet, that is, the surface on the shaft side or the outer peripheral side is not exposed to the air gap, and only the surface facing the adjacent permanent magnet is exposed to the air gap. Alternatively, the groove may be formed only on the surface facing the adjacent permanent magnet. In this way, the influence on the torque force generated in the electric motor by the permanent magnet can be reduced.

  Note that the configuration shown in the above embodiment is an example of the configuration of the present invention, and can be combined with another known technique, and a part thereof is omitted without departing from the gist of the present invention. Needless to say, it is possible to change the configuration.

DESCRIPTION OF SYMBOLS 1 Rotor 2 Shaft 2a Shaft insertion hole 3 Rotor core 4 End plate 5 Permanent magnet 5a Both ends of the permanent magnet in the circumferential direction 6 Magnet insertion hole 6a Both ends in the circumferential direction of the magnet insertion hole 7 Through hole 8 Gap 9 Notch 10 Hole DESCRIPTION OF SYMBOLS 11 Compressor 12 Condenser 13 Depressurizer 14 Evaporator 15 Temperature sensor 16 Bypass circuit (liquid injection circuit)
DESCRIPTION OF SYMBOLS 17 Pressure reducing device 18 On-off valve 19 Sealed container 20 Compression mechanism 21 Electric motor 22 Stator 23 Refrigerant suction pipe 24 Refrigerant discharge pipe 25 Control circuit

Claims (11)

A rotor core formed by laminating a plurality of electromagnetic steel plates each having a plurality of magnet insertion holes provided at equiangular intervals along the circumferential outer periphery;
A plurality of permanent magnets that are inserted alternately into the magnet insertion holes adjacent to each other to form magnetic poles;
With
The plurality of magnet insertion holes are formed such that gaps are generated at both ends in the circumferential direction of the magnet insertion holes when the permanent magnet is inserted,
The permanent magnet is formed with a groove portion parallel to the axial direction so that the cross sections of both end portions in the circumferential direction exposed in the air gap have a wavy uneven shape,
A rotor characterized by being used as a refrigerant flow path for allowing refrigerant to flow through the gap.   The rotor according to claim 1, further comprising an end plate that is processed so as not to block each of the gaps and sandwiches the rotor core in an axial direction.   3. The rotor according to claim 2, wherein the end plate is cut out corresponding to a position around each magnetic pole portion including a circumferential end portion of the adjacent permanent magnets.   The rotor according to claim 2, wherein the end plate is provided with a hole having substantially the same shape as each gap corresponding to the position of each gap.   An electric motor comprising the rotor according to any one of claims 1 to 4. An electric motor according to claim 5;
A compression mechanism driven by the electric motor;
A compressor comprising: A refrigeration cycle apparatus that performs a refrigeration cycle by a compressor, a condenser, a decompression device, and an evaporator,
A compressor according to claim 6,
When the temperature of the permanent magnet rises abnormally, a low-temperature liquid refrigerant is directly injected into the compressor, bypassing between the liquid refrigerant discharge port of the condenser and the gas suction port of the hermetic compressor. A refrigeration cycle apparatus characterized by. A temperature sensor for detecting the temperature of the gas outlet of the compressor;
A bypass circuit configured by connecting a pressure reducing device and an on-off valve in series between a liquid refrigerant discharge port of the condenser and a gas suction port of the hermetic compressor;
A control circuit for controlling the on-off valve based on a temperature detected by the temperature sensor;
The refrigeration cycle apparatus according to claim 7, comprising:   The refrigeration cycle apparatus according to claim 8, wherein the control circuit controls the on-off valve so that a temperature detected by the temperature sensor does not exceed a predetermined temperature set in advance.   The refrigeration cycle apparatus according to claim 8, wherein the control circuit controls the on-off valve to be in an open state when a temperature detected by the temperature sensor exceeds a predetermined temperature set in advance.   An air conditioner comprising the refrigeration cycle apparatus according to any one of claims 7 to 10.

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