JP2013138531A - Permanent magnet motor and compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a permanent magnet motor that is capable of improving motor efficiency by suppressing a current increase by outputting a torque in accordance with pulsation of a load and of improving system reliability and redundancy by suppressing detection of an overcurrent; and a drive system that utilizes this permanent magnet motor.SOLUTION: The permanent magnet motor comprises: a stator with multiple teeth; and a rotor which is provided with a predetermined gap from the stator. In the permanent magnet motor, a pass-through flux in the gap direction is allowed to pass through more easily at least at one of the teeth than at the other teeth, and a pass-through flux in the gap direction is allowed to pass through more easily at least at one of poles of the rotor than at the other poles.

Description

  The present invention relates to a permanent magnet motor and a compressor using the same.

  In general, the torque of an electric motor is proportional to the square of the magnetic flux density vector generated in the gap between the stator and the rotor. In order to generate a constant torque, it is desirable that the magnetomotive force distribution generated in the gap by the stator is a sine wave and the magnetomotive force distribution generated by the rotor in the gap is a sine wave. In practice, however, the stator periodically has a plurality of slot portions for providing the windings and a plurality of teeth portions around which the windings are wound, so that the magnetomotive force distribution Includes a harmonic component called a slot harmonic and causes distortion. In addition, the stator winding is composed of multiple phases (generally, permanent magnet motors have many UVW three-phase alternating current configurations, and other than that, single-phase alternating currents are divided by a capacitor or the like to form two-phase alternating currents. Therefore, the distribution of the combined magnetomotive force of each phase includes a harmonic component called magnetomotive force harmonics, and distortion occurs similarly. Such distortion of the magnetomotive force distribution has been a factor that generates torque ripple and deteriorates drive stability and noise reduction. Prior art document 1 describes a technique for reducing distortion of magnetomotive force distribution by periodically projecting a plurality of teeth portions in the gap direction for the purpose of reducing torque ripple.

Utility Model No. 2559450

  As described above, since the torque of the permanent magnet motor includes ripples, it is general to design such that the ripples are reduced as much as possible and a constant torque is generated.

  However, depending on the drive system on which the motor is mounted, it may not always be a good idea to generate a constant torque. For example, in a refrigerant compressor for compressing a refrigerant, a load fluctuation occurs during the refrigerant compression operation, and the load torque is greatest when the refrigerant is discharged. When a motor that generates a constant torque is designed and applied to a drive system having such a load fluctuation, the current increases when the load pulsation peaks as shown in FIG. Further, during operation at the maximum load, the increase in the current exceeds the overcurrent detection threshold value, so that the motor stop frequency increases, and the reliability of the system may be reduced.

  An object of the present invention is to improve the motor efficiency by outputting torque matched to the pulsation of the load and suppressing the increase in current, and to suppress the overcurrent detection caused by the load fluctuation and improve the reliability. It is an object to provide a possible permanent magnet motor and a compressor using the same.

  In a permanent magnet electric motor comprising a stator having a plurality of teeth and a rotor disposed on an inner peripheral side with a predetermined gap with respect to the stator, at least one tooth among the plurality of teeth The gap in the same number of parts as the teeth configured to increase the transmitted magnetic flux in the rotor is configured such that the transmitted magnetic flux in the gap direction of the teeth is larger than the transmitted magnetic flux in the gap direction of the other teeth. The transmitted magnetic flux in the direction is configured to be larger than the transmitted magnetic flux in the gap direction of other portions.

According to the present invention, it is possible to improve the motor efficiency by outputting torque in accordance with the pulsation of the load and suppressing the increase in current, and also to suppress the overcurrent detection caused by the load fluctuation and improve the reliability. A possible permanent magnet motor and a compressor using the same can be provided.
Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

The cross-section figure of the compressor by one Example of this invention. 1 is a radial cross-sectional view of a permanent magnet motor according to a first embodiment of the present invention. The radial direction sectional view of the permanent magnet motor by the 2nd example of the present invention. The radial direction sectional view of the permanent magnet motor by the 3rd example of the present invention. The radial direction sectional view of the permanent magnet motor by the 3rd example of the present invention. The radial direction sectional view of the permanent magnet motor by the 3rd example of the present invention. The radial direction sectional view of the permanent magnet motor by the 4th example of the present invention. The figure for demonstrating the load fluctuation | variation of a refrigerant compressor.

  An embodiment of the present invention will be described below with reference to the drawings. In the drawings to be cited, the rotation direction is counterclockwise. However, even if the rotation direction is clockwise, the same effect as intended by the present invention can be obtained by reversing the shape.

  FIG. 1 is a sectional view of a compressor according to an embodiment of the present invention. In FIG. 1, the compression mechanism section is formed by meshing a spiral wrap 15 standing upright on the end plate 14 of the fixed scroll member 13 and a spiral wrap 18 standing upright on the end plate 17 of the orbiting scroll member 16. . The air sucked from the suction pipe 23 is compressed by rotating the orbiting scroll member 16 by the crankshaft 6.

  Of the compression chambers 19 (19 a, 19 b,...) Formed by the fixed scroll member 13 and the orbiting scroll member 16, the compression chamber 19 located on the outermost diameter side has both scroll members 13 along with the orbiting motion. , 16 toward the center and the volume gradually decreases. When both the compression chambers 19 a and 19 b reach the vicinity of the center of the fixed scroll member 13 and the orbiting scroll member 16, the compressed gas in both the compression chambers 19 is discharged from the discharge port 20 communicating with the compression chamber 19. The discharged compressed gas passes through a gas passage (not shown) provided in the fixed scroll member 13 and the frame 21 and reaches the pressure vessel 22 below the frame 21, and a discharge pipe provided on the side wall of the pressure vessel 22. (Not shown) is discharged out of the compressor.

  A permanent magnet motor 24 is enclosed in the pressure vessel 22 and rotates at an arbitrary speed to perform a compression operation. An oil reservoir 25 is provided below the permanent magnet motor 24. Oil in the oil reservoir 25 passes through an oil hole 26 provided in the crankshaft 6 due to a pressure difference caused by rotational movement, and the sliding portion between the orbiting scroll member 16 and the crankshaft 6, the sliding bearing 27, etc. Used for lubrication.

  In this compressor, a load fluctuation occurs during the refrigerant compression operation, and the load torque becomes maximum when the refrigerant is discharged. If a permanent magnet motor 24 that drives a drive system (compressor) having such a load fluctuation is applied, a current that increases when the load pulsation peaks as shown in FIG. This will cause a decrease in efficiency. Therefore, in this embodiment, as will be described below, a permanent magnet motor 24 capable of outputting torque in accordance with the peak load is adopted.

  FIG. 2 is a radial sectional view of the permanent magnet motor 24 according to this embodiment. The permanent magnet motor 24 shown in FIG. 2 includes a stator 50 having a plurality of stator teeth 52 and a rotor 1 disposed with a predetermined gap with respect to the stator 50. In addition, at least one of the stator teeth 52 is configured such that the transmitted magnetic flux in the gap direction is easier to transmit than the other teeth, and the transmitted magnetic flux in the gap direction is at least one pole of the rotor 1. It is configured so as to be easier to transmit than the poles.

  That is, the stator 50 is configured such that the transmitted magnetic flux in the gap direction of at least one stator tooth 52 among the plurality of stator teeth 52 is larger than the transmitted magnetic flux in the gap direction of the other stator teeth 52. Is done. On the other hand, in the rotor 1, the transmitted magnetic flux in the gap direction in the same number of parts as the stator teeth 52 configured to increase the transmitted magnetic flux is larger than the transmitted magnetic flux in the gap direction of other parts. It is comprised.

  In FIG. 2, as means for that purpose, at least one of the stator teeth 52 has a portion (stator tooth protrusion 55) protruding in the gap direction, and a part of the outer peripheral surface of one pole of the rotor 1 is formed. It has the structure which has the site | part (rotor outer peripheral surface protrusion part 8) which protrudes in a gap direction. That is, in the stator 50, the tooth configured to increase the transmitted magnetic flux has a portion (stator tooth protruding portion 55) that protrudes in the gap direction as compared with other teeth. On the other hand, in the rotor, a portion (rotor outer peripheral surface protruding portion 8) configured to increase the transmitted magnetic flux is formed to protrude in the gap direction as compared with other portions.

  As described above, the configuration of FIG. 2 is different from that of a normal motor in that the stator teeth projecting portion 55 and the rotor outer peripheral surface projecting portion 8 are provided. In a normal motor, such a protrusion is not provided, and it is designed to output a constant torque with little torque ripple. On the other hand, in the case of the configuration as shown in FIG. 2, a large torque can be obtained when the stator teeth projecting portion 55 and the rotor outer peripheral surface projecting portion 8 face each other, and such positional relationship is one. It can occur only once per rotation.

  Therefore, for example, if the permanent magnet motor of the present embodiment is applied to a system having a peak load once per revolution such as a single rotary compressor, a torque suitable for load fluctuations can be generated under a constant current. It becomes possible. This makes it possible to suppress an increase in current due to load fluctuations, so that the motor efficiency is improved and overcurrent detection is suppressed compared to a motor designed to output a constant torque. Improves reliability and redundancy.

  Further, in the case of a system having a peak load twice per rotation, such as a twin rotary compressor, the same effect can be obtained by providing another set of the stator tooth protrusion 55 and the rotor outer peripheral surface protrusion 8. Can be obtained. At this time, if the peak load appears at equal intervals with respect to the motor rotation angle, the stator teeth protrusions 55 are arranged to face each other with the rotation shaft therebetween, and the rotor outer peripheral surface protrusions 8 are similarly arranged. A greater effect can be obtained by arranging the rotating shafts so as to face each other. On the other hand, if the peak load appears at unequal intervals with respect to the motor rotation shaft, the stator teeth protruding portion 55 and the rotor outer peripheral surface protruding portion 8 are arranged in accordance with the appearance intervals, thereby increasing the load. An effect is obtained.

  Similarly, even in a system having a peak load more than twice per revolution, it is possible to suppress an increase in current due to load fluctuations by configuring the protrusion, so that a constant torque is output. Compared with the designed motor, the motor efficiency is improved, the overcurrent detection is suppressed, and the reliability and redundancy of the system are improved.

  Further, in the case of a system in which a speed increasing gear with a gear ratio α (α> 1) is connected to the motor output shaft and the output shaft side of the gear has a peak load once per rotation, one rotation of the motor is α. It is output as a double rotation speed. Therefore, in the case of a single rotary compressor, the motor is configured to have α pulsation in one rotation of the motor, that is, by providing α combinations of the stator tooth protrusion 55 and the rotor outer peripheral surface protrusion 8. In the same manner as described above, it is possible to generate torque suitable for load fluctuation under a constant current. This makes it possible to suppress an increase in current due to load fluctuations, so that the motor efficiency is improved and overcurrent detection is suppressed compared to a motor designed to output a constant torque. Improves reliability and redundancy. On the other hand, even in the case of a system in which the gear output shaft side has a plurality of peak loads per rotation, the same effect can be obtained by providing the protruding portion according to the above-described concept.

  In FIG. 2, the rotational width of the stator tooth protrusion 55 is about half of the rotational width of the tooth tip, and the rotational width of the rotor outer peripheral surface protrusion 8 is one rotor pole. Although it is about half of the width in the rotation direction, the width of the protrusion may be freely adjusted according to the period during which the peak load is applied or the mechanical angle pitch.

The second embodiment of the present invention will be described below with reference to FIG.
The configuration described in the first embodiment can output torque in accordance with the pulsation of the load, but has a protruding portion in the gap direction, so that the stator inner diameter and the rotor are caused by shaft misalignment and eccentricity during motor assembly. There was a possibility that the outer diameter would interfere mechanically. Interference may cause an increase in vibration and noise. In order to avoid mechanical interference and increase in vibration and noise, if the gap length when facing the protrusion is adjusted to the level of the conventional design, the gap length of the non-protrusion will become large, and sufficient torque will be applied during periods other than the pulsation peak. It cannot be generated.

  In this embodiment, means for solving this problem will be described. In other words, the permanent magnet motor of the present embodiment avoids mechanical interference and increases in vibration and noise by providing a portion that is magnetically easy to transmit magnetic flux rather than a portion that is mechanically easy to transmit magnetic flux. However, it is possible to obtain the same effect as that of the first embodiment while making it possible to output a sufficient torque during a period other than the pulsation peak.

  FIG. 3 shows a radial sectional view of the permanent magnet motor of this embodiment. In FIG. 3, the same components as those in FIG. The configuration of FIG. 3 is different from that of FIG. 2 in that, as shown in the stator magnetic flux transmission facilitating portion 56, at least one tooth, the magnetic permeability of all or part of the magnetic material constituting the tooth is changed to the other It is to make it higher than the magnetic permeability of the magnetic material. That is, as the stator teeth 52 configured to increase the transmitted magnetic flux, a part or all of the stator teeth 52 is formed by a member (stator magnetic flux transmission easy portion 56) having a higher magnetic permeability than other teeth. As this member (the stator magnetic flux transmission facilitating portion 56), for example, an amorphous material or a nanocrystal material may be used.

On the other hand, as shown in the rotor magnetic flux transmission facilitating part 9 as the rotor 1, at least in one pole, the magnetic permeability of all or a part of the magnetic body constituting the pole is determined by the other magnetic body constituting the rotor. The point is that it is higher than the magnetic permeability. That is, the part (rotor magnetic flux transmission easy part 9) configured to increase the transmitted magnetic flux is formed by a member having a higher magnetic permeability than other parts. For example, an amorphous material or a nanocrystal material may be used as the member (the rotor magnetic flux transmission easy portion 9).

  With this configuration, a large torque can be obtained when the stator magnetic flux transmission facilitating portion 56 and the rotor magnetic flux transmission facilitating portion 9 face each other, and such a positional relationship occurs only once per rotation. Can be made. Therefore, as in the first embodiment, in a system having a peak load once per revolution, it is possible to generate torque that is suitable for load fluctuations under a constant current. This makes it possible to suppress an increase in current due to load fluctuations, so that the motor efficiency is improved and overcurrent detection is suppressed compared to a motor designed to output a constant torque. Improves reliability and redundancy.

  Furthermore, since the mechanical gap length is almost uniform in the circumferential direction, by following the design of the conventional motor, mechanical interference and vibration / noise increase due to shaft misalignment and eccentricity during motor assembly can be avoided, The torque does not drop significantly during periods other than the pulsation peak.

  The above is described for a system having a peak load once per rotation. However, by providing a plurality of sets of the stator magnetic flux transmission facilitating portion 56 and the rotor magnetic flux transmission facilitating portion 9, two times per rotation. In the system having the above peak load and the system in which the gears are connected, the same effect as described in the first embodiment can be obtained. Further, the configuration of the rotor 1 or the stator 50 of FIG. 2 may be combined with the configuration of the rotor 1 or the stator 50 shown in the first embodiment.

  As another form of the present embodiment, instead of providing the rotor magnetic flux transmission facilitating portion 9, at least one pole of the rotor 1 relates to all or a part of the permanent magnet 4 constituting the pole. The residual magnetic flux density may be larger than that of other magnets. With such a configuration, a large torque can be obtained when the permanent magnet having a high residual magnetic flux density and the rotor magnetic flux transmission easy portion 9 face each other, and such a positional relationship is generated only once per rotation. Therefore, the same effect as that obtained by the above-described embodiment can be obtained. This configuration may be combined with the configuration shown in the first embodiment, or may be combined with the configuration shown in FIG.

Hereinafter, Example 3 of the present invention will be described with reference to FIGS.
FIG. 4 shows a radial cross-sectional view of the permanent magnet motor according to this embodiment. In FIG. 4, the same components as those in FIG. 4 differs from FIG. 2 in that a stator slit 53 (hole) is first provided in at least one of the stator teeth 52 so that the magnetic flux can be relatively easily transmitted (stator magnetic flux transmission). The easy part 56) is provided. On the other hand, in a plurality of poles of the rotor 1, a rotor slit 7 (hole) is provided in a part of a magnetic body constituting the poles, and at least one pole of the rotor 1 is the rotation A portion (rotor magnetic flux transmission easy portion 9) that relatively facilitates magnetic flux transmission by reducing the sectional area of the slit or eliminating the slit is provided for a plurality of poles provided with the child slit 7. It is.

  With this configuration, a large torque can be obtained when the stator magnetic flux transmission facilitating portion 56 and the rotor magnetic flux transmission facilitating portion 9 face each other, and such a positional relationship occurs only once per rotation. Can be made. Therefore, by adopting the permanent magnet motor of this embodiment in accordance with the load peak of a system having a peak load once per rotation, such as a refrigerant compressor, torque suitable for load fluctuation can be generated under a constant current. Is possible. Although detailed explanation is omitted, it is obvious that the same effect as in the first and second embodiments can be obtained.

  4 is excellent in terms of manufacturability. Basically, when punching a motor core, a punching die provided with a stator slit 53 and a rotor slit 7 as shown in FIG. 4 is used. It can be manufactured by preparing, and unlike the second embodiment, it does not take time and effort to change the constituent material and physical properties of a specific portion. Further, as shown in FIG. 5, the stator slit 53 provided in the stator tooth 52 may be formed in a groove shape that is concave with respect to the gap surface. Moreover, as shown in FIG. 6, you may add the groove-shaped rotor slit 7b which becomes concave with respect to a gap surface among the rotor slits 7 provided in a rotor.

  The above is described for a system having a peak load once per rotation. However, by providing a plurality of sets of the stator magnetic flux transmission facilitating portion 56 and the rotor magnetic flux transmission facilitating portion 9, two times per rotation. In the system having the above peak load and the system in which the gears are connected, the same effect as described in the first embodiment can be obtained. Moreover, you may combine the structure of FIG.4, FIG.5, FIG.6 with the structure of any one or both shown in Example 1 and Example 2. FIG.

  FIG. 7 is a radial sectional view of the permanent magnet motor according to the first embodiment of the present invention. In FIG. 7, the same components as those in FIG. The configuration of FIG. 7 is different from that of FIG. 4 in that the width of the teeth 52a in the rotational direction is made larger than that of the other teeth and a portion (stator magnetic flux transmission easy portion 56) that facilitates magnetic flux transmission is provided. . With such a configuration, a large torque can be obtained when the stator magnetic flux transmission easy part 56 and the rotor magnetic flux transmission easy part 9 face each other, and such a positional relationship occurs only once per rotation. Therefore, in a system having a peak load once per revolution, it is possible to generate a torque suitable for the load fluctuation under a constant current. This makes it possible to suppress an increase in current due to load fluctuations, so that the motor efficiency is improved and overcurrent detection is suppressed compared to a motor designed to output a constant torque. Improves reliability and redundancy. In addition, since the mechanical gap length is almost uniform in the circumferential direction, by following the design of the conventional motor, mechanical interference due to shaft misalignment and eccentricity during motor assembly and vibration and noise increase can be avoided, The torque does not drop significantly during periods other than the pulsation peak. 7 is also excellent in terms of manufacturability. Basically, when punching a motor core, a punching die provided with a stator slit 53 and a rotor slit 7 as shown in FIG. 7 is used. It can be manufactured by preparing, and unlike the second embodiment, it does not take time and effort to change the constituent material and physical properties of a specific portion.

  The above is described for a system having a peak load once per rotation. However, by providing a plurality of sets of the stator magnetic flux transmission facilitating portion 56 and the rotor magnetic flux transmission facilitating portion 9, two times per rotation. In the system having the above peak load and the system in which the gears are connected, the same effect as described in the first embodiment can be obtained. 7 may be combined with any or all of the configurations shown in the first embodiment, the second embodiment, and the third embodiment.

  If the permanent magnet motor of any of the embodiments described above is employed in the compressor of FIG. 1, a compression mechanism (compression chamber 19) that sucks in and compresses and discharges the refrigerant, and this compression mechanism (compression chamber) 19) In the compressor provided with the permanent magnet motor 24 for driving the permanent magnet motor 24, the permeation magnetic flux of the stator 50 increases so that the load torque of the compressor increases during one rotation. When the formed teeth and the portion formed so as to increase the transmitted magnetic flux of the rotor 1 are positioned to face each other through the gap, the effects described in the respective embodiments can be obtained. Can do.

DESCRIPTION OF SYMBOLS 1 Rotor 2 Rotor core 3 Permanent magnet 4 Permanent magnet insertion hole 5 Shaft hole 6 Crankshaft 7 Rotor slit 8 Rotor outer peripheral surface protrusion part 9 Rotor magnetic flux transmission easy part 13 Fixed scroll members 14, 17 End plate 15, 18 Spiral wrap 16 Orbiting scroll member 19 Compression chamber 20 Discharge port 21 Frame 22 Pressure vessel 23 Suction piping 24 Permanent magnet motor 25 Oil reservoir 26 Oil hole 27 Sliding bearing 50 Stator 51 Stator core 52 Stator teeth 53 Stator Slit 54 Stator winding 55 Stator tooth protrusion 56 Stator magnetic flux transmission easy portion

Claims (11)

A stator having a plurality of teeth;
In a permanent magnet motor comprising a rotor disposed on the inner peripheral side with a predetermined gap with respect to the stator,
The transmitted magnetic flux in the gap direction of at least one of the plurality of teeth is configured to be larger than the transmitted magnetic flux in the gap direction of the other teeth,
In the rotor, the transmitted magnetic flux in the gap direction in the same number of parts as the teeth configured to increase the transmitted magnetic flux is configured to be larger than the transmitted magnetic flux in the gap direction of other parts. Characteristic permanent magnet motor. In claim 1,
The teeth configured to increase the transmitted magnetic flux are formed with a portion protruding in the gap direction as compared with other teeth. In the permanent magnet motor according to claim 1 or 2,
In the rotor, the part configured to increase the transmitted magnetic flux is formed so as to protrude in the gap direction as compared with other parts. In claim 1,
A part of or all of the teeth configured to increase the transmitted magnetic flux is formed of a member having a higher magnetic permeability than other teeth. In claim 1 or 4,
In the rotor, the part configured to increase the transmitted magnetic flux is formed by a member having a higher magnetic permeability than other parts. In claim 1 or 4,
In the rotor, the part configured to increase the transmitted magnetic flux is formed by a member having a higher residual magnetic flux density of the permanent magnet than other parts. In claim 1,
Some or all of the plurality of teeth have holes formed therein, and the teeth configured to increase the transmitted magnetic flux are not formed with the above-described holes, or have holes that are not compared to other teeth. A permanent magnet motor having a small cross-sectional area. In claim 1 or 7,
In the rotor, a plurality of holes are formed on the outer peripheral side, and the portion configured to increase the transmitted magnetic flux has a smaller number of holes than other portions, or a cross-sectional area of the holes. The permanent magnet motor is characterized in that it is formed to be small. In claim 1,
A permanent magnet electric motor characterized in that the tooth configured to increase the transmitted magnetic flux is formed to have a larger width in the rotational direction than other teeth. In claim 9,
A permanent magnet electric motor characterized in that at least one pair of teeth having a reduced width in the rotation direction and teeth having an increased width in the rotation direction are arranged to face each other across the rotation shaft. In a compressor equipped with a compression mechanism section that sucks and compresses refrigerant and discharges it, and an electric motor that drives the compression mechanism section,
The motor is a permanent magnet motor according to any one of claims 1 to 10,
The permanent magnet motor is
Teeth formed so that the transmitted magnetic flux of the stator increases during a time when the load torque of the compressor increases during one rotation, and a portion formed such that the transmitted magnetic flux of the rotor increases. Is configured so as to face each other through a gap.