Patent Application
20210036562
The present invention relates to a motor, a compressor, and an air conditioner.
Large-sized air conditioners, such as commercial air conditioners, are required to have an increased capacity of a compressor. In order to increase the capacity of the compressor, it is necessary to enlarge the stroke volume of the compressor and increase the rotation speed of a motor. When the rotation speed of the motor is increased, the frequency of a current flowing through a coil of the motor increases. Thus, in a permanent magnet embedded motor using a rare earth magnet as a permanent magnet, the efficiency of the motor is reduced due to an eddy current generated in the permanent magnet.
In order to reduce the eddy current in a permanent magnet, Patent reference 1 proposes inserting the permanent magnet into a hole formed by punching a steel sheet with an insulating film. Furthermore, Patent reference 2 proposes dividing a permanent magnet in the axial direction and providing an insulating layer between the divided parts of the permanent magnet.
Patent Reference 1: Japanese Patent Application Publication No. 2015-116105 (see
Patent Reference 2: Japanese Patent Application Publication No. 2005-354899 (see
However, when the steel sheet with the insulating film is used as in patent reference 1, the manufacturing cost increases. Further, when the permanent magnet is divided as in patent reference 2, the number of magnets increases and the processing cost increases, and thus the manufacturing cost also increases.
The present invention is intended to solve the above described problems, and an object of the present invention is to reduce eddy current loss without increasing the manufacturing cost.
A motor of the present invention includes a rotor rotatable about a rotation axis, and a stator surrounding the rotor so as to form an air gap between the stator and the rotor. The rotor has a rotor core having a magnet insertion hole and a rare earth magnet disposed in the magnet insertion hole. The rotor core has a plurality of slits on an outer side of the magnet insertion hole in a radial direction about the rotation axis. Each of the plurality of slits has a length in the radial direction which is longer than a length in a circumferential direction about the rotation axis. The plurality of slits have a uniform minimum distance to the magnet insertion hole. When the minimum distance is expressed as T and the air gap is expressed as G, 2.75≤T/G≤5.25 is satisfied.
In the present invention, the eddy current can be reduced because the plurality of slits have the uniform distance to the magnet insertion hole, and the relationship of 2.75≤T/G≤5.25 is satisfied between the distance T and the air gap G. Furthermore, since there is no need to divide the rare earth magnet, the manufacturing cost can be reduced.
The motor 100 includes a rotatable rotor 2 and a stator 1 provided so as to surround the rotor 2. The stator 1 is assembled inside the above-described shell 5. An air gap (i.e., a gap) of, for example, 0.5 mm is provided between the stator 1 and the rotor 2.
Hereinafter, a direction of the axis C1, which is a rotation axis of the rotor 2, is referred to as an “axial direction”. A direction along a circumference about the axis C1 is referred to as a “circumferential direction”. A radial direction about the axis C1 is referred to as a “radial direction”.
The stator 1 includes a stator core 10 and windings 15 wound on the stator core 10. The stator core 10 is formed of a plurality of stack elements which are stacked in the axial direction and fastened by crimping or the like. For example, an electromagnetic steel sheet having a thickness of 0.25 to 0.5 mm and subjected to punching is used as the stack element.
The stator core 10 has a yoke 11 having an annular shape about the axis C1 and a plurality of teeth 12 protruding from the yoke 11 inward in the radial direction. The number of teeth 12 is 18 in this example, but is not limited to 18. The winding 15 is wound around the tooth 12 of the stator core 10 via a not shown insulating portion (insulator). Slots 13 for accommodating the windings 15 are formed each between the teeth 12 adjacent to each other in the circumferential direction.
A plurality of abutting surfaces 17 which are cylindrical surfaces about the axis C1 and a plurality of cutout portions 16 which are flat surfaces parallel to the axis C1 are formed on an outer circumference of the stator core 10. The plurality of abutting surfaces 17 and the plurality of cutout portions 16 are alternately formed in the circumferential direction. Each of the number of the abutting surfaces 17 and the number of the cutout portions 16 is 6 in this example, but is not limited to 6.
The abutting surfaces 17 are fitted to an inner circumferential surface 51 of the shell 5. Thus, the motor 100 is attached to the shell 5. A gap is formed between each cutout portion 16 and the inner circumferential surface 51 of the shell 5. The gap serves as a refrigerant flow passage as will be described later.
The rotor 2 has a rotor core 20 having a plurality of magnet insertion holes 21 formed therein, and permanent magnets 22 disposed in the magnet insertion holes 21. The rotor core 20 is formed of the stack elements which are stacked in the axial direction and fastened by crimping or the like. For example, the stack element is obtained by punching an electromagnetic steel sheet having a thickness of 0.25 to 0.5 mm.
The rotor core 20 has an outer circumferential surface having a cylindrical shape about the axis C1. A shaft hole 24 is formed at a center of the rotor core 20 in the radial direction. A rotational shaft 25 is fixed into the shaft hole 24 by press-fitting.
The magnet insertion holes 21 are formed along an outer circumference of the rotor core 20 and pass through the rotor core 20 in the axial direction. The number of magnet insertion holes 21 is six. The magnet insertion holes 21 are formed at equal intervals in the circumferential direction of the rotor core 20. In an example illustrated in
One permanent magnet 22 is disposed in each of the magnet insertion holes 21. The permanent magnet 22 constitutes a magnetic pole of the rotor 2, and the number of permanent magnets 22 is the same as the number of poles of the rotor 2. That is, the number of magnetic poles of the rotor 2 is six in this example. The number of magnetic poles of the rotor 2 is not limited to six, and it is sufficient that the number of magnetic poles of the rotor 2 is two or more.
The permanent magnet 22 is formed of a rare earth magnet (more specifically, a rare earth sintered magnet) that contains neodymium (Nd), iron (Fe), and boron (B) as main components. The rare earth magnet has a high residual flux density and high coercive force, thereby making it possible to enhance the efficiency of the motor 100 and to enhance the demagnetization resistance. In order to further enhance the coercive force of the permanent magnet 22, dysprosium (Dy) or terbium (Tb) may be added.
The permanent magnet 22 is magnetized to have different magnetic poles on an outer side and an inner side in the radial direction of the rotor core 20. The permanent magnets 22 adjacent to each other in the circumferential direction have the magnetization directions opposite to each other.
Flux barriers 23 are formed on both sides of the magnet insertion hole 21 in the circumferential direction. The flux barrier 23 is a hole extending in the radial direction from an end of the magnet insertion hole 21 in the circumferential direction toward the outer circumference of the rotor core 20. The flux barrier 23 is provided to reduce leakage magnetic flux between adjacent magnetic poles (i.e., magnetic flux flowing through an interpolar portion).
In the rotor core 20, side slits 35 are formed on the inner sides of two flux barriers 23 in the circumferential direction. The side slit 35 is a slit elongated in the circumferential direction and extends along the outer circumference of the rotor core 20 as will be described later.
The rotor core 20 has slits 31, 32, 33, and 34 formed on an outer side of the magnet insertion hole 21 in the radial direction. The slits 31, 32, 33, and 34 are collectively referred to as a slit group 30.
Specifically, the slits 31, 32, 33, and 34 are formed in this order from the center of the magnet insertion hole 21 in the circumferential direction toward one end (the right end in the figure) of the magnet insertion hole 21 in the circumferential direction. Meanwhile, the slits 31, 32, 33, and 34 are formed in this order from the center of the magnet insertion hole 21 in the circumferential direction toward the other end (the left end in the figure) of the magnet insertion hole 21 in the circumferential direction. Two slits 31 are formed symmetrically with respect to the magnetic pole center line M1, two slits 32 are formed symmetrically with respect to the magnetic pole center line M1, two slits 33 are formed symmetrically with respect to the magnetic pole center line M1, and two slits 34 are formed symmetrically with respect to the magnetic pole center line M1. The expression that “the slits are formed symmetrically” means that the slits are symmetrical in shape and arrangement.
Each of the slits 31, 32, 33, and 34 has a shape elongated in the radial direction. The expression “shape elongated in the radial direction” means a shape having a length in the radial direction longer than its length in the circumferential direction. Each of the slits 31, 32, 33, and 34 has a rectangular shape elongated in the radial direction and having four curved corners.
Specifically, the slit 31 has an outer end portion 31a which is an end portion on the outer side in the radial direction, an inner end portion 31b which is an end portion on the inner side in the radial direction, and two side end portions 31c which are end portions on both sides in the circumferential direction. Similarly, the slit 32 has an outer end portion 32a, an inner end portion 32b, and two side end portions 32c. The slit 33 has an outer end portion 33a, an inner end portion 33b, and two side end portions 33c. The slit 34 has an outer end portion 34a, an inner end portion 34b, and two side end portions 34c.
The outer end portions 31a, 32a, 33a, and 34a of the slits 31, 32, 33 and 34 extend along the outer circumference of the rotor core 20. The inner end portions 31b, 32b, 33b, and 34b of the slits 31, 32, 33 and 34 extend along the first edge 21a of the magnet insertion hole 21. Longitudinal directions of the slits 31, 32, 33, and 34 are parallel to the magnetic pole center line M1.
The distance from each of the outer end portions 31a, 32a, 33a, and 34a of the slits 31, 32, 33, and 34 to the outer circumference of the rotor core 20 is desirably twice or more than a plate thickness of each of the stack elements (i.e., the electromagnetic steel sheets) constituting the stator core 10. The slits 31, 32, 33, and 34 are not limited to the shape described herein, and it is sufficient that each slit has a shape having a length in the radial direction longer than its length in the circumferential direction.
Similarly, a distance from the slit 32 to the magnet insertion hole 21, i.e., a distance from the inner end portion 32b of the slit 32 to the first edge 21a of the magnet insertion hole 21 is expressed as T2. A distance from the slit 33 to the magnet insertion hole 21, i.e., a distance from the inner end portion 33b of the slit 33 to the first edge 21a of the magnet insertion hole 21 is expressed as T3. A distance from the slit 34 to the magnet insertion hole 21, i.e., a distance from the inner end portion 34b of the slit 34 to the first edge 21a of the magnet insertion hole 21 is expressed as 14.
The distances T1, T2, T3, and T4 from the slits 31, 32, 33, and 34 to the magnet insertion hole 21 are uniform. That is, T1=T2=T3=T4 is satisfied. The uniform distance from each of the slits 31, 32, 33, and 34 to the magnet insertion hole 21 is expressed as the distance T. Because the distances T1, T2, T3, and T4 are uniform, the inner end portions 31b, 32b, 33b, and 34b of the slits 31, 32, 33, and 34 are located on one straight line B1.
In
The lengths L1, L2, L3, and L4 of the slits 31, 32, 33, and 34 satisfy L1>L2>L3>L4. That is, among the slits 31, 32, 33, and 34, the slit closer to the magnetic pole center line M1 has a longer length, whereas the slit farther from the magnetic pole center line M1 has a shorter length.
The slit 31 has a shape having the length L1 in the radial direction longer than its length W1 in the circumferential direction. Similarly, each of the slits 32, 33, and 34 has a shape having a length in the radial direction longer than its length in the circumferential direction.
An air gap (i.e., gap) G is formed between the outer circumference of the rotor core 20 and an inner circumference 12a of the tooth 12 of the stator 1. The distance T from each of the above-described slits 31, 32, 33, and 34 to the magnet insertion hole 21 and the air gap G satisfy 2.75≤T/G≤5.25. The reason for this will be described later.
The above-described side slits 35 are formed on the inner sides of the flux barriers 23 in the circumferential direction. Each side slit 35 is desirably formed in a position that is as close as possible to the flux barrier 23 in the circumferential direction.
The side slit 35 has an end portion 35a on a side closer to the flux barrier 23, an end portion 35b on a side closer to the magnetic pole center line M1, and two end portions 35c on both sides in the radial direction. The side slit 35 has a shape having a length L5 in the circumferential direction (i.e., the maximum distance between the end portions 35a and 35b) longer than its length W5 in the radial direction (i.e., the maximum distance between the two end portions 35c).
That is, each of the slits 31, 32, 33, and 34 has a shape having a length in the radial direction longer than its length in the circumferential direction, whereas the side slit 35 has a shape having a length in the circumferential direction longer than a length in the radial direction.
By forming the side slits 35 on the inner sides of the flux barriers 23 in the circumferential direction, the magnetoresistance in the flux barrier 23 can be enhanced, and thus the flow of magnetic flux (i.e., leakage magnetic flux) from the permanent magnet 22 to the adjacent magnetic pole across the interpolar portion M2 can be reduced. Thus, the effective magnetic flux that interlinks with the winding 15 of the stator 1 can be increased, so that the efficiency of the motor can be enhanced.
The side slit 35 desirably protrudes to the magnet insertion hole 21 side (i.e., the inner side in the radial direction) with respect to the straight line B1 passing through the inner end portions 31b, 32b, 33b, and 34b of the slits 31, 32, 33, and 34. In other words, the distance from the side slit 35 to the magnet insertion hole 21 is desirably shorter than the distance T described above. Thus, an interval between the side slit 35 and the flux barrier 23 is narrowed, and the effect of reducing the leakage magnetic flux can be enhanced.
Next, a function to reduce the eddy current loss exhibited by the motor 100 of the first embodiment will be described. The permanent magnet 22 is formed of a rare earth magnet and thus has conductivity. While magnetic flux (i.e., stator magnetic flux) generated at the winding 15 of the stator 1 passes through the permanent magnet 22, an eddy current flows inside the permanent magnet 22 due to a change with time (dΦ/dt) of the stator magnetic flux Φ passing through the permanent magnet 22. The eddy current leads to a loss (i.e., eddy current loss), and causes the reduction in the efficiency of the motor. Further, the temperature of the permanent magnet 22 increases due to Joule heating, which causes high-temperature demagnetization of the permanent magnet 22.
In the first embodiment, the slits 31, 32, 33, and 34 of the rotor core 20 achieve the reduction in the eddy current loss. First, for comparison with the motor 100 of the first embodiment, a motor 100H of a comparison example will be described.
That is, the distance T1 from the slit 31 closest to the center of the magnetic pole to the magnet insertion hole 21 is the shortest, and the distance T2 from the slit 32 to the magnet insertion hole 21 is the second shortest. The distances T3 and T4 from the slits 33 and 34 to the magnet insertion hole 21 are equal to each other and longer than the distances T1 and T2.
From the result shown in
The reason why the eddy current loss is reduced in this way is considered as follows. In the motor 100H of the comparison example, the distances from the slits 31, 32, 33, and 34 to the magnet insertion hole 21 are not uniform, and the magnetic path between the slit 31 and the magnet insertion hole 21 is the narrowest. Thus, when the stator magnetic flux flows through this part, magnetic saturation occurs. When the magnetic saturation occurs in a part of the rotor core 20H facing the permanent magnet 22, the eddy current is more likely to flow in the permanent magnet 22.
In contrast, in the motor 100 of the first embodiment (
Generally, in order to reduce the eddy current loss, a configuration in which the permanent magnet 22 is divided into a plurality of parts insulated from each other by an insulating film is employed. However, this configuration increases the number of parts due to the division of the permanent magnet 22. Further, as the size of the permanent magnet 22 is reduced, the processing cost of the permanent magnet 22 increases. For these reasons, dividing the permanent magnet 22 leads to an increase in the manufacturing cost.
In contrast, in the motor 100 of the first embodiment, the slits 31, 32, 33, and 34 have the uniform distance T to the magnet insertion hole 21, and T/G is set within a range of 2.75≤T/G≤5.25. Thus, the effect of reducing the eddy current loss can be obtained without dividing the permanent magnet 22 to the same extent as the case in which the permanent magnet 22 is divided.
As described above, since the magnetic path having a width corresponding to the distance T is formed between each of the slits 31, 32, 33, and 34 and the magnet insertion hole 21, the stator magnetic flux directed to the permanent magnet 22 can be released to the magnetic path. Thus, the stator magnetic flux is less likely to be concentrated on the permanent magnet 22, and thus the demagnetization of the permanent magnet 22 can be suppressed. That is, the demagnetization resistance can be enhanced.
Next, a refrigerant flow passage of the motor 100 will be described. The motor 100 is used, for example, in the compressor 500 (
Thus, as shown in
The cutout portions 16 are desirably formed evenly in the circumferential direction of the stator 1. This is because such an arrangement of the cutout portions 16 can make the flow of refrigerant uniform. In the stator 1, six cutout portions 16 are formed. However, the number of cutout portions 16 is not limited to six and may be five or less, or seven or more.
Through-holes 18 are formed in the yoke 11 of the stator core 10. The through-holes 18 pass through the stator core 10 in the axial direction. During operation of the compressor 500, the refrigerant flows through the through-holes 18 in the axial direction. That is, the through-holes 18 form the refrigerant flow passages.
In an example illustrated in
The through-hole 18 is desirably formed on a straight line Al in the radial direction that passes through the center of the tooth 12 in the circumferential direction. That is, the through-hole 18 is desirably formed at equal distances from the slots 13 adjacent in the circumferential direction. This is to make the through-hole 18 interrupt the flow of magnetic flux through the tooth 12 and the yoke 11 as least as possible.
The stator 1 has the cutout portions 16 and the through-holes 18 as the refrigerant flow passages, so that a sufficient flow rate of the refrigerant through the compressor 500 can be obtained. The refrigerant passes through the motor 100, and heat of the motor 100 is dissipated by the refrigerant. Thus, an increase in the temperature of the motor 100 is reduced, and thus the demagnetization of the permanent magnet 22 at high temperature can be suppressed.
In this example, the stator 1 includes the cutout portions 16 and the through-holes 18 as the refrigerant flow passages, but the stator 1 may be configured to include either the cutout portions 16 alone or the through-holes 18 alone.
Two first through-holes 26 are provided for each magnetic pole and formed on both sides of the magnetic pole center line M1 in the circumferential direction. One second through-hole 27 is provided for each magnetic pole and formed on the magnetic pole center line M1. One third through-hole 28 is provided for each magnetic pole and formed to straddle the interpolar portion M2. Among the through-holes 26, 27, and 28, the inner diameter of the first through-hole 26 is the smallest, while the inner diameter of the second through-hole 27 is the largest. Each of the through-holes 26, 27, and 28 has a circular shape, but is not limited thereto.
In this way, the rotor 2 includes the through-holes 26, 27, and 28 as the refrigerant flow passages, and thus the rotor 2 can be efficiently cooled by the refrigerant flowing through the through-holes 26, 27, and 28. Thus, an increase in the temperature of the permanent magnet 22 is reduced, the demagnetization of the permanent magnet 22 at high temperature can be suppressed.
In
Since at least one of the through-holes 26, 27, and 28 (in this example, the first through-hole 26 and the second through-hole 27) satisfies H≥D/4, the refrigerant flow passage can be positioned close to the permanent magnet 22. As a result, the permanent magnet 22 is efficiently cooled, and thus the effect of suppressing the demagnetization of the permanent magnet 22 at high temperature can be enhanced.
Next, the crimping portion 29 of the rotor core 20 will be described.
The crimping portion 29 is provided on the outer side of the magnet insertion hole 21 of the rotor core 20 in the radial direction and on the magnetic pole center line M1 (i.e., at the center of the magnet insert hole 21 in the circumferential direction). As described above, a wide space is provided between the two slits 31 of the rotor core 20, and thus the crimping portion 29 can be formed between the two slits 31. Further, the crimping portion 29 and the slit 31 are spaced apart from each other, making it possible to avoid the concentration of magnetic flux.
As described above, the motor 100 of the first embodiment of the present invention has a plurality of slits 31, 32, 33, and 34 disposed on the outer side of the magnet insertion hole 21 of the rotor core 20 in the radial direction. The slits 31, 32, 33, and 34 are elongated in the radial direction. These plurality of slits 31, 32, 33, and 34 have the uniform distance T to the magnet insertion hole 21, and the distance T and the air gap G between the stator 1 and the rotor 2 satisfy 2.75≤T/G≤5.25. With this configuration, the eddy current flowing through the permanent magnets 22 can be reduced. That is, the eddy current loss can be reduced, and the efficiency of the motor can be enhanced. Since there is no need to divide the permanent magnet 22, an increase in the manufacturing cost can be avoided.
Further, the stator magnetic flux directed toward the permanent magnet 22 can be released to the magnetic path between each of the slits 31, 32, 33, and 34 and the magnet insertion hole 21. Thus, the concentration of the stator magnetic flux on the permanent magnet 22 can be suppressed, and the demagnetization of the permanent magnet 22 can be suppressed.
Each of the plurality of slits 31, 32, 33, and 34 extends parallel to the magnetic pole center line M1, and thus the magnetic flux emanated from the permanent magnet 22 can be guided to the stator 1 by the shortest distance.
Since the plurality of slits 31, 32, 33, and 34 are formed symmetrically with respect to the magnetic pole center line M1, the spatial harmonic of the magnetic flux generated in the air gap is suppressed, and torque ripple (torque pulsation) and exciting force in the radial direction are also suppressed. Thus, noise and vibration can be suppressed.
The interval between two slits 31 formed closest to the center of the magnet insertion hole 21 in the circumferential direction among the plurality of slits 31, 32, 33, and 34 is wider than the interval between the other two adjacent slits. Thus, the crimping portion 29 can be formed between the two slits 31.
The rotor core 20 includes the side slits 35 on both ends of the magnet insertion hole 21 in the circumferential direction, and thus the leakage magnetic flux between the adjacent magnetic poles can be reduced.
Since the magnet insertion hole 21 extends linearly in the direction perpendicular to the magnetic pole center line M1, a core portion located on the outer side of the magnet insertion hole 21 in the radial direction can be reduced. Thus, when the rotor 2 rotates, the centrifugal force applied to the core portion on the outer side of the magnet insertion hole 21 in the radial direction is reduced, and thus the durability of the rotor core 20 can be enhanced.
The rotor core 20 includes the through-holes 26, 27, and 28 passing through the rotor core 20 in the axial direction, and thus the rotor 2 can be cooled by the refrigerant flowing through the through-holes 26, 27, and 28. Thus, the demagnetization of the permanent magnet 22 at high temperature can be suppressed.
The diameter D of the rotor core 20 and the distance H from the axis C1 to the center of each of the through-holes 27 and 28 satisfy D/4≤H, and thus the permanent magnet 22 can be efficiently cooled by the refrigerant flowing through the through-holes 27 and 28. As a result, the effect of suppressing the demagnetization of the permanent magnet 22 at high temperature can be enhanced.
The winding 15 of the stator 1 has the conductor 15a made of copper or aluminum and the insulating film 15b covering the surface of the conductor 15a, and thus corrosion of the winding 15 can be prevented in, for example, the refrigerant of the compressor 500.
Further, since the stator core 10 has the through-holes 18 passing through the stator core 10 in the axial direction and has the cutout portions 16 on the outer circumference of the stator core 10, the motor 100 can be cooled, for example, by the refrigerant flowing through the through-holes 18.
Next, a second embodiment of the present invention will be described.
Each of the above-described slits 31, 32, 33, and 34 of the first embodiment extends parallel to the magnetic pole center line M1 (see
The slits 31, 32, 33, and 34 located on one side (the right side in
The slits 31, 32, 33, and 34 located on the same side of the magnetic pole center line M1 desirably extend parallel to each other. With this configuration, the interval between the slits is not narrowed locally, and magnetic saturation is less likely to occur between the slits.
In the second embodiment, each of the slits 31, 32, 33, and 34 is elongated in the radial direction (in other words, has a length in the radial direction longer than its length in the circumferential direction). The slits 31, 32, 33, and 34 have the uniform distance T (i.e., minimum distance) to the magnet insertion hole 21, and this distance T satisfies 2.75≤T/G≤5.25.
An interval S1 between two slits 31 adjacent to each other across the magnetic pole center line M1 in the circumferential direction, an interval S2 between adjacent slits 31 and 32 in the circumferential direction, an interval S3 between adjacent slits 32 and 33 in the circumferential direction, and an interval S4 between adjacent slits 33 and 34 in the circumferential direction satisfy S1>S3>S2>S4. The crimping portion 29 (
The motor of the second embodiment is configured in a similar manner to the motor of the first embodiment except that the slits 31, 32, 33, and 34 of the rotor core 20A are inclined with respect to the magnetic pole center line M1.
In the second embodiment, while the slits 31, 32, 33, and 34 of the rotor core 20A are inclined with respect to the magnet pole center line M1, the slits 31, 32, 33, and 34 have the uniform distance T to the magnet insertion hole 21, and this distance T satisfies 2.75≤T/G≤5.25. Thus, the eddy current loss can be reduced as in the first embodiment.
Next, a third embodiment of the present invention will be described.
The above-described slits 31, 32, 33, and 34 of the first embodiment are arranged at unequal intervals in the circumferential direction. In contrast, the slits 31, 32, 33, and 34 of the third embodiment are arranged at equal intervals in the circumferential direction.
In
The slits 31, 32, 33, and 34 extend parallel to the magnetic pole center line M1 as in the first embodiment. However, as described in the second embodiment, the slits 31, 32, 33, and 34 may extend to be inclined with respect to the magnetic pole center line M1. In such a case, the slits 31, 32, 33, and 34 located on one side of the magnetic pole center line M1 and the slits 31, 32, 33, and 34 located on the other side of the magnetic pole center line M1 are desirably inclined symmetrically with respect to the magnetic pole center line M1.
As in the first embodiment, the slits 31, 32, 33, and 34 have the uniform distance (denoted by T) to the magnet insertion hole 21, and this distance T satisfies 2.75≤T/G≤5.25.
The motor of the third embodiment is configured in a similar manner to the motor of the first embodiment except that the slits 31, 32, 33, and 34 of the rotor core 20B are arranged at equal intervals.
In the third embodiment, the slits 31, 32, 33, and 34 of the rotor core 20B are arranged at equal intervals in the circumferential direction. Thus, in addition to the effects described in the first embodiment, the stator magnetic flux flowing into the rotor core 20B can be evenly dispersed, and magnetic saturation between the slits of the rotor core 20B can be suppressed.
Next, a fourth embodiment of the present invention will be described.
Although the above-described rotor core 20 of the first embodiment has eight slits for each magnetic pole, the rotor core 20C of the second embodiment has two slits 31 for each magnetic pole. The two slits 31 are arranged at equal distances from the magnetic pole center line M1.
The two slits 31 extend parallel to the magnetic pole center line M1, but may be inclined with respect to the magnetic pole center line M1 as described in the second embodiment. In such a case, the two slits 31 are desirably inclined symmetrically with respect to the magnetic pole center line M1.
The two slits 31 have the uniform distance (denoted by T) to the magnet insertion hole 21, and this distance T satisfies 2.75≤T/G≤5.25.
The motor of the fourth embodiment is configured in a similar manner to the motor of the first embodiment except that the rotor core 20C has two slits 31 for each magnetic pole.
In the fourth embodiment, while the number of slits for each magnetic pole of the rotor core 20C is two, the slits 31 have the uniform distance T to the magnet insertion hole 21, and this distance T satisfies 2.75≤T/G≤5.25. Thus, the eddy current loss can be reduced as in the first embodiment.
In the first to fourth embodiments, the number of slits for each magnetic pole of the rotor core is eight or two, but it is sufficient that the number of slits is two or more.
Next, a compressor to which the motor of each embodiment described above is applicable will be described.
The compressor 500 is a scroll compressor and includes, in a container 502, a compression mechanism 510, the motor 100 that drives the compression mechanism 510, a main shaft 501 that connects the compression mechanism 510 and the motor 100, a sub-frame 503 that supports an end (a sub-shaft part) of the main shaft 501 opposite to the compression mechanism 510, and a lubricant 504 stored in an oil reservoir 505 at a bottom of the closed container 502.
The compression mechanism 510 includes a fixed scroll 511 and a swing scroll 512 combined together to form a compression chamber between their plate-like scroll teeth, an Oldham ring 513, a compliant frame 514, and a guide frame 515.
A suction pipe 506 passing through the container 502 is press-fitted to the fixed scroll 511. A discharge pipe 507 is provided so as to pass through the container 502. The discharge pipe 507 allows high-pressure refrigerant gas discharged from a discharge port 511a of the fixed scroll 511 to be discharged to the outside (a refrigeration cycle).
The container 502 has the cylindrical shell 5 into which the motor 100 is fitted by shrink-fitting. A glass terminal 508 for electrically connecting the stator 1 of the motor 100 to a drive circuit is fixed to the container 502 by welding.
The motor 100 of the first to fourth embodiments described above has the motor efficiency enhanced by reducing the eddy current loss. Thus, by using the motor 100 as a power source of the compressor 500, the operation efficiency of the compressor 500 can be enhanced, and consumption energy can be reduced.
Herein, the scroll compressor has been described as an example of the compressor, but the motor of each embodiment described above may also be applied to any compressor other than the scroll compressor.
Next, an air conditioner 400 including the above described compressor 500 will be described.
The compressor 401, the condenser 402, and the throttle device 403 are provided in an outdoor unit 410. The compressor 401 is constituted of the compressor 500 illustrated in
The operation of the air conditioner 400 is as follows. The compressor 401 compresses sucked refrigerant and sends out the compressed refrigerant. The condenser 402 exchanges heat between the refrigerant flowing from the compressor 401 and the outdoor air to condense and liquefy the refrigerant, and sends out the liquefied refrigerant to the refrigerant pipe 407. The outdoor fan 405 supplies the outdoor air to the condenser 402. The throttle device 403 adjusts the pressure and the like of the refrigerant flowing through the refrigerant pipe 407 by changing its opening degree.
The evaporator 404 exchanges heat between the refrigerant brought into a low-pressure state by the throttle device 403 and indoor air to cause the refrigerant to take heat from the indoor air and evaporate (vaporizes), and then sends out the evaporated refrigerant to the refrigerant pipe 407. The indoor fan 406 supplies the indoor air to the evaporator 404. Thus, cooled air deprived of heat at the evaporator 404 is supplied into the room.
The motor 100 described in each of the first to fourth embodiments is applicable to the compressor 401 (the compressor 500 in
The compressor 500 to which the motor of any one of the first to fourth embodiments is applied is not limited to the air conditioner 400 illustrated in
Although the desirable embodiments of the present invention have been specifically described, the present invention is not limited to the above-described embodiments, and various modifications or changes can be made to these embodiments without departing from the scope of the present invention.
This application is a U.S. national stage application of International Patent Application No. PCT/JP2018/014989 filed on Apr. 10, 2018, the disclosure of which is incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2018/014989 | 4/10/2018 | WO | 00 |
