Stator, electric motor, compressor, and air conditioning device

Abstract

In stators using distributed winding, there has been a problem wherein, when windings of a single phase are connected in parallel, depending on the placement positions of windings accommodated in a slot, the winding inductance becomes unbalanced, the electric current is not divided equally in the parallel connection, and copper loss occurring in the windings increases, thereby reducing electric motor efficiency. The purpose of the present disclosure is to provide a stator with which it is possible to increase electric motor efficiency. This stator comprises: a stator core configured by stacking electromagnetic steel sheets in the axial direction; and windings wound on the stator core in the manner of distributed winding. The stator core includes a plurality of slots in the circumferential direction. The windings include first windings and second windings, and an outer winding and a first inner-outer winding are connected in series in the first windings, and an inner winding and a second inner-outer winding are connected in series in the second windings.

Description

Stators, electric motors, compressors and air conditioners

[0001] The present disclosure relates to a stator, an electric motor, a compressor, and an air conditioner.

[0002] There are two types of winding methods for the stator of an electric motor: concentrated winding and distributed winding. Distributed winding is easier to suppress the electromagnetic excitation force generated in the stator, and because it has a higher winding coefficient than concentrated winding, it can effectively utilize the magnetic force generated by the rotor, thereby improving the efficiency and output of the electric motor.

[0003] For example, Patent Document 1 discloses a stator using distributed winding that reduces the manufacturing cost of the winding and improves the efficiency of the electric motor.

[0004] International Publication No. 2020 / 089994

[0005] However, when one phase of winding is connected in parallel, the winding inductance can become unbalanced depending on the position of the winding housed in the slot, causing current to flow unevenly among the parallel connections, increasing copper loss in the winding and resulting in reduced motor efficiency.

[0006] An object of the present disclosure is to provide a stator that can improve the efficiency of an electric motor.

[0007] The stator according to this disclosure includes a stator core formed by laminating electromagnetic steel sheets in the axial direction, and a winding wound in a distributed winding manner around the stator core. The stator core has a plurality of slots in the circumferential direction, and the winding has a first winding and a second winding, the first winding having an outer layer winding and a first inner and outer layer winding connected in series, and the second winding having an inner layer winding and a second inner and outer layer winding connected in series. In a plane perpendicular to the axial direction, a circle centered on the rotation axis of the stator core and passing through the outermost diameter portions of the slots in the radial direction is defined as a first circle, a circle centered on the rotation axis of the stator core and passing through the innermost diameter portion of the stator core in the radial direction is defined as a second circle, and a circle centered on the rotation axis of the stator core and dividing the first and second circles in half radially is defined as a third circle. The outer layer winding is arranged across two slots, with the radial centers of the outer layer windings in one slot and the other slot located outer than the third circle. The first inner and outer layer winding is arranged across two slots, with the radial center of the first inner and outer layer winding in one slot located outer than the third circle, and the radial center of the first inner and outer layer winding in the other slot located inner than the third circle. The inner layer winding is arranged across two slots, with the radial centers of the inner layer winding in one slot and the other slot located inner than the third circle. The second inner and outer layer winding is arranged across two slots, with the radial center of the second inner and outer layer winding in one slot located on the outer diameter side of the third circle, and the radial center of the second inner and outer layer winding in the other slot located on the inner diameter side of the third circle.

[0008] According to the present disclosure, the efficiency of the electric motor can be improved.

[0009] 1. A cross-sectional view of an electric motor according to embodiment 1. A cross-sectional view of a rotor according to embodiment 1. A cross-sectional view of a stator according to embodiment 1. A circuit diagram of windings according to embodiment 1. A perspective view of a stator according to embodiment 1. A cross-sectional view taken along line A-A in FIG. 3. A connection diagram of U-phase, V-phase, and W-phase windings according to embodiment 1. A top view showing a view of windings according to embodiment 1 inserted into an inserter. A side view of an inserter according to embodiment 1. A cross-sectional view of a stator according to comparative example 1. A circuit diagram of windings according to comparative example 1. A cross-sectional view of a stator according to comparative example 2. A circuit diagram of windings according to comparative example 2. A waveform diagram of current flowing in a U-phase winding of an electric motor according to comparative example 1. A waveform diagram of current flowing in a U-phase winding of an electric motor according to comparative example 2. A waveform diagram of current flowing in a U-phase winding of an electric motor according to embodiment 1. Numerical data of current flowing in a U-phase winding of electric motors according to comparative example 1, comparative example 2, and embodiment 1. Data of copper loss occurring in the U-phase winding of electric motors according to comparative example 1, comparative example 2, and embodiment 1. A schematic diagram for explaining coil impedance. 1 is data showing the inductance ratio between the first winding and the second winding in a motor according to comparative example 1 and a motor according to embodiment 1. FIG. 2 is a schematic diagram showing magnetic flux flowing around a winding when the winding is positioned on the outer diameter side of the slot. FIG. 3 is a schematic diagram showing magnetic flux flowing around a winding when the winding is positioned on the inner diameter side of the slot. FIG. 4 is a cross-sectional view showing an example of a compressor according to embodiment 2. FIG. 5 is a cross-sectional view showing the configuration of a compression mechanism part according to embodiment 2. FIG. 6 is a diagram showing a schematic configuration of an air conditioner according to embodiment 3. FIG. 7 is a refrigerant circuit diagram showing the flow of refrigerant during cooling operation in an air conditioner according to embodiment 3. FIG. 8 is a refrigerant circuit diagram showing the flow of refrigerant during heating operation in an air conditioner according to embodiment 3.

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following drawings, identical or corresponding parts are designated by the same reference numerals, and their description will not be repeated. Furthermore, in the following drawings, including FIG. 1, the dimensional relationships between components may differ from those in reality. Furthermore, the configurations of components shown in the entire specification are merely illustrative and are not limited to these descriptions. The direction along the circumference of a circle centered on the axis C1, which is the center of rotation of the stator 2, is referred to as the "circumferential direction," the direction parallel to the axis C1 as the "axial direction," and the direction perpendicular to the axis C1 as the "radial direction." The drawings also show an x-y-z Cartesian coordinate system to facilitate mutual understanding of the drawings. The z-axis is a coordinate axis parallel to the axis C1 of the stator 2. The y-axis is a coordinate axis perpendicular to the z-axis. The x-axis is a coordinate axis perpendicular to both the y-axis and the z-axis.

[0011] Embodiment 1. <Motor Configuration> Fig. 1 is a cross-sectional view of an electric motor 1 according to Embodiment 1. The electric motor 1 shown in Fig. 1 is configured with a circular stator 2 and a rotor 3 disposed on the inner diameter side of the stator 2 with a gap of 0.25 to 1.25 mm therebetween.

[0012] <Configuration of Rotor> Fig. 2 is a cross-sectional view of the rotor 3 according to the present embodiment 1. The rotor 3 shown in Fig. 2 is configured by a circular rotor core 50 and a plurality of permanent magnets 58.

[0013] The rotor core 50 is cylindrical and centered on the axis C1, and is constructed by laminating multiple electromagnetic steel sheets, each having a thickness t, in the axial direction and fastening them together with caulking 53 and rivets (not shown). The thickness t is, for example, 0.1 to 0.7 mm.

[0014] As shown in FIG. 2, the rotor core 50 is provided with a magnet insertion hole 51, a shaft hole 52, and a slit 54 that penetrate the rotor core 50 in the axial direction.

[0015] One or more magnet insertion holes 51 are provided in the rotor core 50, and permanent magnets 58 are inserted into the magnet insertion holes 51 to form magnetic poles. In Fig. 2, six magnet insertion holes 51 are provided, but the number of magnet insertion holes 51 is not limited to six, and two or more holes may be provided.

[0016] The shaft hole 52 is a hole into which a shaft (not shown) is inserted. The shaft is, for example, a crankshaft 65. Details of the crankshaft 65 will be described later.

[0017] The slits 54 are provided on the outer diameter side of the magnet insertion holes 51. The slits 54 can regulate the flow of magnetic flux from the permanent magnets 58 toward the stator core 10, thereby suppressing the electromagnetic excitation force generated in the stator core 10 during operation of the electric motor 1. The shape and number of the slits 54 are arbitrary, and the rotor core 50 does not necessarily need to have slits 54.

[0018] The permanent magnets 58 may be rare earth magnets whose main components are neodymium (Nd), iron (Fe), and boron (B), or ferrite magnets whose main component is iron oxide (FeO). Either rare earth magnets or ferrite magnets may be used, but rare earth magnets have a higher energy product (the product of magnetic flux density B and magnetic field H), which is one indicator of the performance of the permanent magnets 58, than ferrite magnets. Therefore, to ensure the same efficiency of the electric motor 1 for both, the volume of the permanent magnets 58 can be reduced when using rare earth magnets compared to ferrite magnets.

[0019] The permanent magnets 58 are arranged at regular intervals around the circumferential direction of the rotor core 50. In Fig. 2, one permanent magnet 58 is provided for each magnet insertion hole 51, but two or more permanent magnets 58 may be provided for each magnet insertion hole 51.

[0020] <Configuration of Stator> Fig. 3 is a cross-sectional view of the stator 2 according to the present embodiment 1. The stator 2 shown in Fig. 3 is configured with a circular stator core 10, a plurality of windings 20, and a plurality of insulating papers (not shown).

[0021] The stator core 10 is annular and centered on the axis C1, and is constructed by laminating multiple electromagnetic steel sheets, each having a thickness of 0.1 to 0.7 mm, in the axial direction and fastening them together by caulking (not shown). The stator core 10 also includes an annular back yoke 11 and multiple teeth 12 that protrude radially inward from the back yoke 11. Furthermore, slots 13 are formed between the teeth 12 in the circumferential direction, providing insertion spaces for the windings 20. In the first embodiment, four D-cuts are provided on the outer peripheral surface of the back yoke 11, penetrating it in the axial direction. The number of D-cuts is not limited to four, and it is sufficient that one or more D-cuts are provided.

[0022] The teeth 12 are arranged at regular intervals around the circumferential direction of the stator core 10, and in the present embodiment 1, 18 teeth 12 are provided. The number of teeth 12 is not limited to 18, and it is sufficient that two or more teeth are provided.

[0023] The windings 20 are formed by winding a conducting wire around the teeth 12. The conducting wire is made up of a conductor (not shown) whose main component is copper (Cu) or aluminum (Al) and an insulating coating (not shown) that covers the outer periphery of the conductor. The main component of the conductor is not limited to copper (Cu) or aluminum (Al), but may be silver (Ag) or iron (Fe). However, copper (Cu) and aluminum (Al) are more inexpensive than silver (Ag), and can be procured more cheaply. Furthermore, copper (Cu) and aluminum (Al) have lower resistivity than iron (Fe), which reduces losses in the windings 20 and improves the efficiency of the electric motor 1. Therefore, by forming the conductor of the windings 20 of the first embodiment from copper (Cu) or aluminum (Al), an inexpensive and highly efficient electric motor 1 can be constructed.

[0024] In the electric motor 1 according to the first embodiment, the winding 20 is wound using distributed winding. In contrast to concentrated winding, in which the winding 20 is wound around one tooth 12, distributed winding, in which the winding is wound across multiple teeth 12, tends to result in coil ends that are higher in the axial direction. However, because distributed winding has a higher winding factor than concentrated winding, it can effectively utilize the magnetic flux generated from the permanent magnet 50, resulting in higher efficiency and higher output. Furthermore, compared to concentrated winding, distributed winding can make the magnetic flux linking the winding 20 closer to a sinusoidal wave, making it easier to suppress the electromagnetic excitation force generated in the stator core 10 and reducing the sound vibrations generated by the electric motor 1.

[0025] 3, the stator 2 according to the first embodiment has one winding 20 wound across three teeth 12. The detailed configuration of the winding 20 will be described later.

[0026] The insulating paper is made of, for example, polyethylene terephthalate film (polyester film), and is used to insulate the slots 13 of the stator 2, the interphase insulation of the windings 20, and the coil ends.

[0027] <Winding Configuration> A description will be given of the configuration of winding 20 in stator 2 according to embodiment 1. Winding 20 of stator 2 according to embodiment 1 has three phases consisting of U-phase, V-phase, and W-phase, but for the sake of explanation, only the U-phase is shown in Fig. 3, and the V-phase and W-phase are omitted.

[0028] Fig. 4 is a circuit diagram of the winding 20 according to the present embodiment 1. As shown in Fig. 4, the winding 20 according to the present embodiment 1 has a first winding 21 and a second winding 22 connected in parallel.

[0029] 3 and 4, the first winding 21 includes a winding housed on the outer diameter side of the slot 13 and the outer diameter side of the slot 13 (hereinafter referred to as the "outer layer winding 21a"), a winding housed on the inner diameter side of the slot 13 and the outer diameter side of the slot 13 (hereinafter referred to as the "first inner and outer layer winding 21b"), and a winding housed on the inner diameter side of the slot 13 and the outer diameter side of the slot 13 (hereinafter referred to as the "third inner and outer layer winding 21c") connected in series. The outer layer winding 21a, the first inner and outer layer winding 21b, and the third inner and outer layer winding 21c are each formed by bundling a plurality of electric wires.

[0030] As shown in Fig. 3, the outer layer winding 21a, the first inner and outer layer winding 21b, and the third inner and outer layer winding 21c are each wound at a three-slot pitch, in other words, every three slots. The slot pitch represents the angle between adjacent slots in the circumferential direction. In the stator 2 according to the first embodiment, 18 slots 13 are formed at equal intervals in the stator core 10, and therefore the slot pitch is 360 [degrees] / 18 = 20 [degrees] in mechanical angle.

[0031] That is, the same outer layer winding 21a is inserted into the third slot counting from the slot 13 into which the outer layer winding 21a is inserted. In other words, the outer layer winding 21a, the first inner and outer layer winding 21b, and the third inner and outer layer winding 21c are wound so as to straddle three teeth 12.

[0032] Because the winding 20 is wound at a 3-slot pitch, each winding 20 is wound over a mechanical angle of 360 degrees × 3 / 18 = 60 degrees. In other words, the coil pitch is 60 degrees. The coil pitch represents the angle in the circumferential direction from one coil side 210 of the winding 20 (described later) to the other coil side 210 of the same winding 20.

[0033] The outer layer winding 21a, the first inner and outer layer winding 21b, and the third inner and outer layer winding 21c are each arranged at a pitch of three slots.

[0034] The second winding 22 is configured such that a winding housed on the inner diameter side of the slot 13 and the inner diameter side of the slot 13 (hereinafter referred to as the "inner layer winding 22a"), a winding arranged every three slots from the inner layer winding 22a and housed on the inner diameter side of the slot 13 and the outer diameter side of the slot 13 (hereinafter referred to as the "second inner and outer layer winding 22b"), and a winding arranged every three slots from the second inner and outer layer winding 22b and housed on the inner diameter side of the slot 13 and the outer diameter side of the slot 13 (hereinafter referred to as the "fourth inner and outer layer winding 22c") are connected in series. The inner layer winding 22a, the second inner and outer layer winding 22b, and the fourth inner and outer layer winding 22c are each formed by bundling a plurality of electric wires.

[0035] As shown in Fig. 3, in the stator core 10 according to the first embodiment, a first circle C11, a second circle C12, and a third circle C13 are defined. Specifically, in a plane perpendicular to the axial direction, the first circle C11 is an imaginary circle that is centered on the axis C1 of the stator core 10 and passes through the outermost diameter portions of the slots 13 in the radial direction. The second circle C12 is an imaginary circle that is centered on the axis C1 of the stator core 10 and passes through the innermost diameter portions of the stator core 10 in the radial direction. The third circle C13 is an imaginary circle that is centered on the axis C1 of the stator core 10 and bisects the first circle C11 and the second circle C12 in the radial direction.

[0036] The following describes the outer layer winding 21a provided in the first winding 21. As shown in Fig. 3, the outer layer winding 21a is arranged across two slots 13. In one slot 13 and the other slot 13, either the radial center or the center of gravity of the coil side 210 of the outer layer winding 21a is located on the outer diameter side of the third circle C13.

[0037] Next, a description will be given of the first inner and outer layer winding 21b provided in the first winding 21. As shown in Fig. 3 , the first inner and outer layer winding 21b is disposed across two slots 13, and in one slot 13, either the radial center or the center of gravity of the coil side 210 of the first inner and outer layer winding 21b is located on the outer diameter side of the third circle C13, while in the other slot 13, either the radial center or the center of gravity of the coil side 210 of the first inner and outer layer winding 21b is located on the inner diameter side of the third circle C13.

[0038] Next, a description will be given of the third inner and outer layer winding 21c provided in the first winding 21. As shown in Fig. 3 , the third inner and outer layer winding 21c is disposed across two slots 13, and in one slot 13, either the radial center or the center of gravity of the coil side 210 of the third inner and outer layer winding 21c is located on the outer diameter side of the third circle C13, while in the other slot 13, either the radial center or the center of gravity of the coil side 210 of the third inner and outer layer winding 21c is located on the inner diameter side of the third circle C13.

[0039] The following describes the inner layer winding 22a provided in the second winding 22. As shown in Fig. 3, the inner layer winding 22a is disposed across two slots 13, and either the radial center or the center of gravity of the coil side 210 of the inner layer winding 22a in one slot 13 and the other slot 13 is located radially inward of the third circle C13.

[0040] The following describes the second inner and outer layer winding 22b provided in the second winding 22. As shown in Fig. 3 , the second inner and outer layer winding 22b is disposed across two slots 13, with either the radial center or the center of gravity of the coil side 210 of the second inner and outer layer winding 22b being located on the outer diameter side of the third circle C13 in one slot 13, and either the radial center or the center of gravity of the coil side 210 of the second inner and outer layer winding 22b being located on the inner diameter side of the third circle C13 in the other slot 13.

[0041] Next, a description will be given of the fourth inner and outer layer winding 22c provided in the second winding 22. As shown in Fig. 3, the fourth inner and outer layer winding 22c is disposed across two slots 13, and in one slot 13, either the radial center or the center of gravity of the coil side 210 of the fourth inner and outer layer winding 22c is located on the outer diameter side of the third circle C13, while in the other slot 13, either the radial center or the center of gravity of the coil side 210 of the fourth inner and outer layer winding 22c is located on the inner diameter side of the third circle C13.

[0042] That is, the stator 2 according to the first embodiment has six windings 20 per phase.

[0043] Although the stator 2 according to the first embodiment has six windings 20 per phase, the total number of windings 20 is not limited to six. The first winding 21 may include an outer layer winding 21a and a first inner and outer layer winding 21b. Similarly, the second winding 22 may include an inner layer winding 22a and a second inner and outer layer winding 22b. In this case, the total number of windings 20 per phase is four.

[0044] Fig. 5 is a perspective view of the stator 2 according to the first embodiment. Fig. 6 is a cross-sectional view taken along line AA in Fig. 3.

[0045] 5-6 , each winding 20 has a coil side 210, a coil end 211, and a coil root 212. The coil side 210 is the portion that is inserted into the slot 13. The coil end 211 is the portion that is formed so as to fit along the axial end face of the stator core 10. The coil root 212 is the portion that protrudes axially from the stator core 10 and is formed between the coil side 210 and the coil end 211.

[0046] A gap 213 is formed between the axial end face of the stator core 10 and the coil end 211. If the axial height of the gap 213 is Hc, it is desirable to satisfy the relationship 4≦Hc≦8 mm. By satisfying 4≦Hc mm, the blades 201 can be easily inserted into the gap 213 while ensuring the mechanical strength of the blades 201 provided in the inserter 200 in the winding process described below, thereby improving winding productivity.

[0047] Furthermore, in a 6-pole, 18-slot electric motor 1, it is common to configure the motor with three windings 20 per phase. In this case, however, each winding 20 is large, and therefore Hc tends to increase to 8 mm or more. In the stator 2 according to the first embodiment, six windings 20 are configured per phase, and therefore each winding 20 can be made smaller. In other words, the stator 2 according to the first embodiment satisfies Hc≦8 mm. This makes it possible to suppress a significant increase in the circumferential length of the windings 20, and therefore suppress an increase in copper loss occurring in the windings.

[0048] 3, a first winding 21 and a second winding 22 are wound around the stator core 10, so that six windings 20 are wound on the stator 2 per phase. Each winding 20 is wound at a three-slot pitch.

[0049] The stator 2 according to the first embodiment has six windings 20 wound per phase, which is the same number as the number of poles of the rotor 3 (the rotor 3 according to the first embodiment has six poles). Since the windings 20 of the stator 2 according to the first embodiment are wound at a three-slot pitch, the coil pitch of the stator 2 is 360 degrees × 3 / 18 = 60 degrees in mechanical angle. The coil pitch represents the angle in the circumferential direction from one coil side 210 of the winding 20 to the other coil side 210 of the same winding 20. In other words, one winding 20 is wound over a mechanical angle of 60 degrees. Furthermore, the magnetic pole pitch of the rotor 3 is 360 degrees / 6 = 60 degrees in mechanical angle. In other words, adjacent magnetic poles of the rotor 3 are spaced apart by a mechanical angle of 60 degrees.

[0050] In the electric motor 1 according to the first embodiment, the coil pitch of the stator 2 and the magnetic pole pitch of the rotor 3 both match at a mechanical angle of 60 degrees. A winding configuration in which the coil pitch and the magnetic pole pitch are equal is called a "full-pitch winding." In the electric motor 1 according to the first embodiment, the primary winding factor Kw1 is 1. The primary winding factor Kw1 is an index indicating the proportion of magnetic flux that can contribute to the effective magnetic flux of the fundamental wave that links with the winding 20 of the stator 2, out of the magnetic flux generated from the permanent magnet 50 provided in the rotor 3. In other words, in the electric motor 1 according to the first embodiment, the primary winding factor Kw1 can be maximized to 1, so that the magnetic flux of the permanent magnet 50 can be effectively utilized, and the efficiency of the electric motor 1 can be improved.

[0051] In the electric motor 1 according to the first embodiment, the total number S of slots 13 in the stator 2, the number of phases M, and the number P of poles in the rotor 3 are S / (MP) = 18 / (3 × 6) = 1. That is, the number of slots 13 per phase and per pole (hereinafter referred to as the "number of slots per phase per pole") is 1. Since the number of slots per phase per pole is an integer, it is possible to reduce the electromagnetic excitation force generated in the stator 2 while the electric motor 1 is operating.

[0052] 7 is a connection diagram of the U-phase, V-phase, and W-phase of the winding 20 according to the present embodiment 1. As shown in FIG. 7, the first winding 21 and the second winding 22 connected in parallel are configured as a Y connection connected to the neutral point N.

[0053] The electric motor 1 according to the first embodiment is a full-pitch winding with a pole number P of 6 and a slot number S of 18. In this winding configuration, the primary winding factor Kw1 is 1, and the tertiary winding factor Kw3 is also 1.

[0054] In a motor 1 having a tertiary winding coefficient Kw3 of 1, if the U, V, and W phases are configured as a delta connection, a current will be generated that circulates between the U, V, and W phases (hereinafter referred to as a "circulating current"). When the motor 1 is operating, the circulating current does not contribute to the torque generated in the rotor 3, but rather causes an increase in copper loss in the winding 20.

[0055] Therefore, by configuring the electric motor 1 according to the first embodiment with a Y connection, a closed loop is not formed between the U phase, V phase, and W phase, and the path of the current circulating between the U phase, V phase, and W phase is cut off. As a result, no circulating current is generated in the Y connection, and the efficiency of the electric motor 1 can be improved.

[0056] <Winding Production Method> A method for producing the winding 20 according to the present embodiment 1 will now be described. Fig. 8 is a top view showing the winding 20 according to the present embodiment 1 inserted into the inserter 200. To insert the winding 20 into the slot 13, the inserter 200 as shown in Fig. 8 is used.

[0057] 9 is a side view of the inserter 200 according to the first embodiment. As shown in FIGS. 8 and 9, the inserter 200 includes a plurality of blades 201 and a connecting portion 202 that connects the blades 201. The number of blades 201 is the same as the number of slots 13, and the blades 201 are arranged at equal intervals in the circumferential direction around the axis C1, and extend axially from the connecting portion 202.

[0058] 8, the outer layer winding 21a, the first inner / outer layer winding 21b, the second inner / outer layer winding 21c, the inner layer winding 22a, the third inner / outer layer winding 22b, and the fourth inner / outer layer winding 22c are mounted on the inserter 200. Each winding is wound across three blades 201.

[0059] The inserter 200 is inserted into the inner diameter side of the stator core 10 so that each blade 201 faces the radially inner side of the tooth 12, and then is pulled out in the axial direction. As a result, each winding wire stretched across the blade 201 is accommodated in the slot 13 and wound around the stator core 10.

[0060] <Comparative Examples> In order to explain the effects of the electric motor 1 according to the first embodiment, the configurations and effects of comparative examples 1 and 2 will be described.

[0061] <Explanation of Comparative Example 1> Fig. 10 is a cross-sectional view of a stator 2a according to Comparative Example 1. Fig. 11 is a circuit diagram of a winding 20a according to Comparative Example 1. As with Figs. 3 and 4, Figs. 10 and 11 show only the U-phase for explanation.

[0062] As shown in FIG. 11, in the winding 20a according to the first comparative example, a first winding 31 and a second winding 32 are connected in parallel.

[0063] As shown in FIGS. 10 and 11 , the first winding 31 is configured such that a winding housed on the outer diameter side of the slots 13 and on the outer diameter side of the slots 13 (hereinafter referred to as the “first outer layer winding 31 a”), a winding arranged every six slot pitches from the first outer layer winding 31 a and housed on the outer diameter side of the slots 13 and on the outer diameter side of the slots 13 (hereinafter referred to as the “second outer layer winding 31 b”), and a winding arranged every six slot pitches from the second outer layer winding 31 b and housed on the outer diameter side of the slots 13 and on the outer diameter side of the slots 13 (hereinafter referred to as the “third outer layer winding 31 c”) are connected in series.

[0064] The second winding 32 is configured such that a winding housed between the inner diameter sides of the slots 13 (hereinafter referred to as the "first inner layer winding 32a"), a winding arranged every six slot pitches from the second inner layer winding 32a and housed between the inner diameter sides of the slots 13 (hereinafter referred to as the "second inner layer winding 32b"), and a winding arranged every six slot pitches from the second inner layer winding 32b and housed between the inner diameter sides of the slots 13 (hereinafter referred to as the "third inner layer winding 32c") are connected in series.

[0065] <Explanation of Comparative Example 2> Fig. 12 is a cross-sectional view of a stator 2b according to Comparative Example 2. Fig. 13 is a circuit diagram of a winding 20b according to Comparative Example 2. As with Figs. 3 and 4, Figs. 12 and 13 show only the U-phase for explanation.

[0066] As shown in FIG. 13, in the winding 20b according to the second comparative example, a first winding 41 and a second winding 42 are connected in series.

[0067] As shown in FIGS. 12 and 13 , the first winding 41 is configured such that a winding housed on the outer diameter side of the slots 13 and on the outer diameter side of the slots 13 (hereinafter referred to as the “first outer layer winding 41 a”), a winding arranged every six slot pitches from the first outer layer winding 41 a and housed on the outer diameter side of the slots 13 and on the outer diameter side of the slots 13 (hereinafter referred to as the “second outer layer winding 41 b”), and a winding arranged every six slot pitches from the second outer layer winding 41 b and housed on the outer diameter side of the slots 13 and on the outer diameter side of the slots 13 (hereinafter referred to as the “third outer layer winding 41 c”) are connected in series.

[0068] The second winding 42 is configured such that a winding housed between the inner diameter sides of the slots 13 (hereinafter referred to as the "first inner layer winding 42a"), a winding arranged every six slot pitches from the first inner layer winding 42a and housed between the inner diameter sides of the slots 13 (hereinafter referred to as the "second inner layer winding 42b"), and a winding arranged every six slot pitches from the second inner layer winding 42b and housed between the inner diameter sides of the slots 13 (hereinafter referred to as the "third inner layer winding 42c") are connected in series.

[0069] <Effects of the Electric Motor According to the First Embodiment> The effects of the electric motor 1 according to the first embodiment will be described. Fig. 14 is a waveform diagram of the current flowing in the U-phase winding of the electric motor 1a according to the first comparative example. Fig. 15 is a waveform diagram of the current flowing in the U-phase winding of the electric motor 1b according to the second comparative example. Fig. 16 is a waveform diagram of the current flowing in the U-phase winding of the electric motor 1 according to the first embodiment. Figs. 14 to 16 each show the waveform of the current flowing in the U-phase winding calculated by numerical analysis when the rotation speed of the rotor 3 is 90 [rps] and the torque of the rotor 3 is 15 [Nm].

[0070] 14, in the electric motor 1a according to the first comparative example, there is a significant difference between the waveform of the current Iu31 flowing through the first winding 31 and the waveform of the current Iu32 flowing through the second winding 32. Specifically, the current Iu32 flowing through the second winding 32 is larger than the current Iu31 flowing through the first winding 41.

[0071] 15, in the electric motor 1b according to the second comparative example, the waveform of the current Iu41 flowing through the first winding 41 matches the waveform of the current Iu42 flowing through the second winding 42. This is because the first winding 41 and the second winding 42 are connected in series in the winding according to the second comparative example, and therefore Iu41 = Iu42.

[0072] 16 , in motor 1 according to the first embodiment, the waveform of current Iu21 flowing through first winding 21 and the waveform of current Iu22 flowing through second winding 22 also roughly match. That is, although winding 20 according to the first embodiment is connected in parallel like winding 20a according to comparative example 1, motor 1 according to the first embodiment can suppress the imbalance in current between first winding 21 and second winding 22 compared to motor 1a according to comparative example 1.

[0073] FIG. 17 shows numerical data of the currents flowing through the U-phase windings of the electric motors 1a, 1b, and 1 according to the first comparative example, the second comparative example, and the first embodiment.

[0074] As shown in FIG. 17, when the ratio Iu31 / Iu32 of the current Iu31 of the first winding 31 to the current Iu32 of the second winding 32 in the electric motor 1a according to the first comparative example is calculated, Iu31 / Iu32 = (Iu3 × 0.472) / (Iu3 × 0.730) = 64.7%.

[0075] In contrast, as shown in FIG. 17, when the ratio Iu21 / Iu22 of the current Iu21 of the first winding 21 to the current Iu22 of the second winding 22 in the electric motor 1 according to the first embodiment is calculated, Iu21 / Iu22 = (Iu2 × 0.491) / (Iu2 × 0.509) = 96.5 [%].

[0076] That is, compared to the electric motor 1a according to the comparative example 1, in the electric motor 1 according to the present embodiment 1, the ratio of the current Iu21 of the first winding 21 to the current Iu22 of the second winding 22 can be made close to 100% and it can be seen that the imbalance in the current between the first winding 21 and the second winding 22 can be suppressed.

[0077] Next, an explanation will be given of the effect of suppressing the current imbalance between the first winding 21 and the second winding 22 in the electric motor 1 according to the present embodiment 1. Fig. 18 shows data on copper loss generated in the U-phase winding of the electric motors 1a, 1b, and 1 according to the comparative example 1 and the comparative example 2 and the present embodiment 1. Fig. 18 shows the copper loss generated in the U-phase winding calculated by numerical analysis when the rotation speed of the rotor 3 is 90 [rps] and the torque of the rotor 3 is 15 [Nm].

[0078] 18 , in the electric motor 1a according to Comparative Example 1, a copper loss W3 of 73.7 [W] occurs in the U-phase winding 20a. In contrast, in the electric motor 1b according to Comparative Example 2, a copper loss W4 of 40 [W] occurs in the U-phase winding 20b, which is 45.7 [%] reduced compared to the copper loss occurring in the electric motor 1a according to Comparative Example 1. In the electric motor 1 according to the first embodiment, a copper loss W2 of 40.5 [W] occurs in the U-phase winding 20b, which is reduced to a value close to the copper loss occurring in the electric motor 1b according to Comparative Example 2.

[0079] The occurrence of copper loss will be analyzed in detail. As shown in Fig. 18, in the electric motor 1a according to the first comparative example, the copper loss W31 occurring in the first winding 31 is 21.7 [W], while the copper loss W32 occurring in the second winding 32 is 52.0 [W]. The reason why the copper loss W32 occurring in the second winding 32 is large is because the current Iu32 flowing through the second winding 32 is large, as shown in Fig. 17.

[0080] 18, in the electric motor 1b according to the comparative example 2, the copper loss W41 generated in the first winding 41 is 20.0 [W], whereas the copper loss W42 generated in the second winding 42 is 20.0 [W]. In the stator 2b according to the comparative example 2, the first winding 41 and the second winding 42 are connected in series, and therefore no current imbalance occurs, and therefore the copper loss W41 generated in the first winding 41 and the copper loss W42 generated in the second winding 42 have the same value.

[0081] 18, in the electric motor 1 according to the first embodiment, the copper loss W21 generated in the first winding 21 is 19.5 [W], whereas the copper loss W22 generated in the second winding 22 is 21.0 [W]. Thus, in the electric motor 1 according to the first embodiment, even though the first winding 21 and the second winding 22 are connected in parallel, the values ​​of the copper loss W21 generated in the first winding 21 and the copper loss W22 generated in the second winding 22 are similar, and the influence of the current imbalance is reduced.

[0082] Next, a description will be given of why the electric motor 1 according to the present embodiment 1 can suppress the current imbalance. Fig. 19 is a schematic diagram for explaining the impedance of the coils.

[0083] As shown in FIG. 19 , the equivalent circuit of the first winding 21 can be considered as a series connection of a first winding resistance R21 [Ω] and a first winding inductance L21 [H]. The equivalent circuit of the second winding 22 can be considered as a series connection of a second winding resistance R22 [Ω] and a second winding inductance L22 [H]. The first winding resistance R21 and the second winding resistance R22 are determined by the material, wire diameter, perimeter, and other factors of the electric wire constituting the winding 20. The first winding inductance L21 and the second winding inductance L22 are determined by the number of turns of the winding 20, the magnetic flux linkage, and other factors. The first winding impedance Z21 and the second winding impedance Z22 are expressed by the following Equation 1-2. In Equation 1-2, j is a complex number, and ω [rad / sec] is angular velocity.

[0084]

[0085]

[0086] The current imbalance occurs due to the imbalance between the first winding impedance Z21 and the second winding impedance Z22. From Equation 1-2, it can be seen that in order to suppress the imbalance between the first winding impedance Z21 and the second winding impedance Z22, it is desirable that the first winding resistance R21 and the second winding resistance R22 match, and that the first winding inductance L21 and the second winding inductance L22 match.

[0087] If the wires constituting the winding 20 are made of the same material, wire diameter, and circumferential length, the first winding resistance R21 and the second winding resistance R22 will generally match. However, as will be described later, the flux linkage changes depending on the positional relationship within the slots 13 of the winding 20, so the first winding inductance L21 and the second winding inductance L22 do not necessarily match. Therefore, the electric motor 1 according to the first embodiment aims to approximate the values ​​of the first winding inductance L21 and the second winding inductance L22.

[0088] The relationship between the first winding inductance L21 and the second winding inductance L22 in the electric motor 1 according to the present embodiment 1 will now be described. Fig. 20 shows data representing the inductance ratio (L1 / L2) between the first winding 21 and the second winding 22 in the electric motor 1a according to the comparative example 1 and the electric motor 1 according to the present embodiment 1. The closer the inductance ratio (L1 / L2) is to 100%, the closer the values ​​of the first winding inductance L21 and the second winding inductance L22 become.

[0089] 20, the inductance ratio of the electric motor 1a according to the first comparative example is 104.6%, while the inductance ratio of the electric motor 1 according to the first embodiment is 100.9%. That is, the values ​​of the first winding impedance Z21 and the second winding impedance Z22 can be made closer in the electric motor 1 according to the first embodiment than in the electric motor 1a according to the first comparative example.

[0090] The reason why the inductance ratio (L1 / L2) of the electric motor 1 according to the first embodiment approaches 100% compared to the electric motor 1a according to the comparative example 1 will be explained. Fig. 21 is a schematic diagram showing the magnetic flux flowing around the winding 20 when the winding 20 is located on the outer diameter side of the slot 13. Fig. 22 is a schematic diagram showing the magnetic flux flowing around the winding 20 when the winding 20 is located on the inner diameter side of the slot 13.

[0091] 21 , magnetic flux flows in a circular pattern along the outer periphery of winding 20, and the amount of this magnetic flux determines the inductance of winding 20. When winding 20 is positioned on the outer diameter side of slot 13, the magnetic flux passes from tooth 12 toward back yoke 11, from back yoke 11 toward the adjacent tooth 12, from the adjacent tooth 12 through slot 13, and returns to tooth 12, forming a closed-loop magnetic path.

[0092] As shown in Figure 22, when the winding 20 is positioned on the inner diameter side of the slot 13, the magnetic flux flows from the tooth 12 through the slot 13 to the adjacent tooth 12, then flows toward the inner diameter side of the tooth 12, and returns to the tooth 12, forming a closed loop magnetic path.

[0093] That is, even within the same slot 13, inductance tends to be large near the winding 20 arranged on the outer diameter side of the slot 13 because there is less air in the magnetic path near the winding 20. On the other hand, inductance tends to be small near the winding 20 arranged on the inner diameter side of the slot 13 because there is more air in the magnetic path near the winding 20 compared to near the winding 20 arranged on the outer diameter side of the slot 13.

[0094] As a result, by connecting the winding 20 arranged on the outer diameter side of the slot 13 and the winding 20 arranged on the inner diameter side of the slot 13 in parallel, the current flowing through each winding 20 becomes unbalanced due to the difference in inductance, and a current with a large amplitude flows through the winding 20 arranged on the inner diameter side of the slot 13, and a current with a small amplitude flows through the winding 20 arranged on the outer diameter side of the slot 13.

[0095] From the above, in the electric motor 1a according to Comparative Example 1, when comparing the first winding 31 in which the first outer layer winding 31, the second outer layer winding 31c, and the third outer layer winding 32b are connected in series with the second winding 32 in which the first inner layer winding 31b, the second inner layer winding 32a, and the third inner layer winding 32c are connected in series, the relationship between the current Iu31 flowing in the first winding 31 and the current Iu32 flowing in the second winding 32 is Iu31<Iu32.

[0096] As shown in FIGS. 13 and 15 , in the electric motor 1b according to Comparative Example 2, the first winding 41 and the second winding 42 are connected in series. This prevents current imbalance due to an imbalance in inductance between the first winding 41 and the second winding 42, and therefore prevents an increase in internal copper loss. However, compared to the electric motor 1 according to the first embodiment, in which the first winding 21 and the second winding 22 are connected in parallel, connecting the first winding 41 and the second winding 42 in series as in the electric motor 1b according to Comparative Example 2 reduces the number of turns of each winding 20 by half. This doubles the cross-sectional area of ​​each wire constituting the winding 20, resulting in thicker wires. This thicker wire can make it more difficult to bend the wire when winding the winding 20 around the stator core 10 and increase the cycle time in the winding process.

[0097] In electric motor 1 according to the first embodiment, even though first winding 21 and second winding 22 are connected in parallel, it is possible to match the amplitude and phase of current Iu21 flowing in first winding 21 and current Iu22 flowing in second winding 22 as shown in Fig. 16. In other words, electric motor 1 according to the first embodiment can reduce copper loss occurring in the windings, thereby improving motor efficiency and suppressing deterioration in productivity of winding 20.

[0098] As described above, the stator 2 according to the first embodiment includes the stator core 10 formed by laminating electromagnetic steel sheets in the axial direction, and the winding 20 wound in distributed winding on the stator core 10. The stator core 10 has a plurality of slots 13 in the circumferential direction, and the winding 20 has a first winding 21 and a second winding 22, the first winding 21 having an outer layer winding 21a and a first inner and outer layer winding 21b connected in series, and the second winding 22 having an inner layer winding 22a and a second inner and outer layer winding 22b connected in series. In a plane perpendicular to the axial direction, when a circle centered on the axis C1 of the stator core 10 and passing through the outermost diameter portion of the slot 13 in the radial direction is defined as a first circle C11, a circle centered on the axis C1 of the stator core 10 and passing through the innermost diameter portion of the stator core 10 in the radial direction is defined as a second circle C12, and a circle centered on the axis C1 of the stator core 10 and dividing the first circle C11 and the second circle C12 in the radial direction into two equal parts is defined as a third circle C13, the outer layer winding 21a is arranged across the two slots 13, and the radial centers of the outer layer winding 21a in one slot 13 and the other slot 13 are located on the outer diameter side of the third circle C13. The first inner and outer layer winding 21b is arranged across two slots 13, with the radial center of the first inner and outer layer winding 21b located radially outer than the third circle C13 in one slot 13 and the radial center of the first inner and outer layer winding 21b located radially inner than the third circle C13 in the other slot 13. The inner layer winding 22a is arranged across two slots 13, with the radial center of the inner layer winding 22a located radially inner than the third circle C13 in one slot 13 and the other slot 13. The second inner and outer layer winding 22b is arranged across two slots 13, with the radial center of the second inner and outer layer winding 22b located radially outer than the third circle C13 in one slot 13 and the radial center of the second inner and outer layer winding 22b located radially inner than the third circle C13 in the other slot 13.

[0099] Due to this feature, the electric motor 1 according to the first embodiment can prevent the inductance of the windings 20 from becoming unbalanced even when one phase of the windings 20 is connected in parallel. As a result, the current is evenly divided into the parallel connections, which reduces copper loss occurring in the windings 20. This provides the effect of improving the efficiency of the electric motor.

[0100] Furthermore, in the electric motor 1 according to the first embodiment, by connecting one-phase windings 20 in parallel, the number of turns of each winding 20 can be increased compared to when one-phase windings 20 are connected in series. In other words, the cross-sectional area of ​​each electric wire constituting the winding 20 can be reduced. As a result, each electric wire can be made thinner, which makes it easier to bend the electric wire when winding 20 around stator core 10, thereby providing the effect of suppressing a decrease in productivity of winding 20.

[0101] Second Embodiment <Configuration and Operation of Compressor> A compressor 60 according to the second embodiment will be described. Fig. 23 is a cross-sectional view showing an example of the compressor 60 according to the second embodiment. The compressor 60 is, for example, a rotary compressor. Note that the compressor 60 is not limited to a rotary compressor, and may be another type of compressor 60 such as a low-pressure compressor or a scroll compressor.

[0102] 23 , compressor 60 includes electric motor 1 according to the first embodiment, a crankshaft 65 as a rotating shaft, a compression mechanism 70, and a sealed container 90. Electric motor 1 drives compression mechanism 70. Compression mechanism 70 compresses refrigerant (not shown) drawn from accumulator 100. The configuration of compression mechanism 70 will be described later.

[0103] The crankshaft 65 connects the electric motor 1 and the compression mechanism 70. The crankshaft 65 has a shaft main body 65a fixed to the rotor 3 of the electric motor 1 and an eccentric shaft 65b fixed to the rolling piston 80 of the compression mechanism 70.

[0104] The sealed container 90 is cylindrical and houses the electric motor 1 and the compression mechanism 70. Refrigerant oil (not shown) is stored in an oil reservoir at the bottom of the sealed container 90. The refrigerant oil is a lubricant that lubricates the sliding parts of the compression mechanism 70 (for example, the fitting part between the rolling piston 80 and the eccentric shaft 65b). The refrigerant oil passes through an oil supply passage formed inside the crankshaft 65 to lubricate the sliding parts of the compression mechanism 70.

[0105] The compressor 60 further has a discharge pipe 91 and a terminal 92 attached to the upper part of the sealed container 90. The discharge pipe 91 discharges the refrigerant compressed by the compression mechanism 70 to the outside of the sealed container 90. The discharge pipe 91 is connected to the refrigerant circuit shown in FIG. 26 or 27.

[0106] The terminal 92 is connected to a driving device (not shown) provided outside the compressor 60. The terminal 92 also supplies a motor current Ia to the winding 20 of the stator 2 of the electric motor 1 via a lead wire 93. This causes the rotor 3 of the electric motor 1 to rotate.

[0107] Fig. 24 is a cross-sectional view showing the configuration of a compression mechanism 70 according to the second embodiment. As shown in Fig. 24, the compression mechanism 70 has a cylinder 71, a rolling piston 80, a vane 81, an upper bearing 82, and a lower bearing 84. The cylinder 71 has a suction port 71a, a cylinder chamber 71b, and a vane groove 71c. The suction port 71a is connected to the accumulator 100 via a suction pipe 72. The suction port 71a is a passage through which the refrigerant drawn from the accumulator 100 flows, and is connected to the cylinder chamber 71b.

[0108] In the following description, the direction along the circumference of a circle centered on the crankshaft 65 is referred to as the "circumferential direction," the direction of the axis C1 that is the center of rotation of the crankshaft 65 is referred to as the "axial direction," and the direction of a line that is perpendicular to the axial direction and passes through the crankshaft 65 is referred to as the "radial direction." The drawings also show an x-y-z Cartesian coordinate system to facilitate understanding of the drawings. The z-axis is a coordinate axis parallel to the axis C1 of the crankshaft 65. The y-axis is a coordinate axis perpendicular to the z-axis. The x-axis is a coordinate axis perpendicular to both the y-axis and the z-axis.

[0109] The cylinder chamber 71b is a cylindrical space centered on the axis C1. The cylinder chamber 71b accommodates the eccentric shaft portion 65b of the crankshaft 65, the rolling piston 80, and the vane 81. When viewed in the z-axis direction, the rolling piston 80 has a ring-like shape. The rolling piston 80 is fixed to the eccentric shaft portion 65b of the crankshaft 65.

[0110] The vane groove 71c communicates with the cylinder chamber 71b. A vane 81 is attached to the vane groove 71c. A back pressure chamber 71d is formed at the end of the vane groove 71c. The vane 81 is pressed toward the axis C1 by a spring (not shown) disposed in the back pressure chamber 71d, thereby contacting the outer circumferential surface of the rolling piston 80. As a result, the vane 81 divides the space surrounded by the inner circumferential surface of the cylinder chamber 71b, the outer circumferential surface of the rolling piston 80, the upper bearing 82, and the lower bearing 84 into a suction-side working chamber (hereinafter referred to as the "suction chamber 86a") and a compression-side working chamber (hereinafter referred to as the "compression chamber 86b"). The suction chamber 86a communicates with the suction port 71a.

[0111] The vane 81 reciprocates in the y-axis direction within the vane groove 71c when the rolling piston 80 is rotating eccentrically. The vane 81 is, for example, plate-shaped. Note that in the example shown in Figure 24, the rolling piston 80 and the vane 81 are separate bodies, but the rolling piston 80 and the vane 81 may also be integrated.

[0112] 23, the upper bearing 82 closes the end of the cylinder chamber 71b on the +z-axis side. The lower bearing 84 closes the end of the cylinder chamber 71b on the −z-axis side. The upper bearing 82 and the lower bearing 84 are each fixed to the cylinder 71 by fastening members such as bolts (not shown).

[0113] The upper bearing 82 and the lower bearing 84 each have a discharge port that discharges the compressed refrigerant to the outside of the cylinder chamber 71b. The discharge ports of the upper bearing 82 and the lower bearing 84 communicate with the compression chamber 86b of the cylinder chamber 71b. The discharge ports are provided with discharge valves (not shown). The discharge valves open when the pressure of the refrigerant compressed in the compression chambers reaches or exceeds a predetermined pressure, and discharge the high-temperature, high-pressure refrigerant into the internal space of the sealed container 90. Note that the lower bearing 84 does not necessarily have to have a discharge port.

[0114] An upper discharge muffler 83 is attached to the upper bearing 82 with fastening members (e.g., bolts). A muffler chamber 83a is provided between the upper bearing 82 and the upper discharge muffler 83. This allows the refrigerant discharged from the discharge port of the upper bearing 82 to diffuse into the muffler chamber 83a, thereby suppressing discharge noise caused by the refrigerant being discharged from the discharge port of the upper bearing 82.

[0115] Furthermore, a lower discharge muffler 85 is attached to the lower bearing 84 with fastening members (e.g., bolts). A muffler chamber 85a is provided between the lower bearing 84 and the lower discharge muffler 85. This allows the refrigerant discharged from the discharge port of the lower bearing 84 to diffuse into the muffler chamber 85a, thereby suppressing the generation of discharge noise from the refrigerant discharged from the lower bearing 84. Note that if a discharge port is formed in either the upper bearing 82 or the lower bearing 84, the discharge muffler may be provided in the frame in which the discharge port is formed.

[0116] The compressor 60 according to the second embodiment uses the electric motor 1 described in the first embodiment, and therefore can obtain the same advantages as those described in the first embodiment. As a result, a highly efficient compressor 60 can be provided.

[0117] Third Embodiment An air conditioning apparatus 250 according to a third embodiment will now be described in detail with reference to the drawings.

[0118] <Configuration and Operation of Air Conditioning Apparatus> Figure 25 is a diagram showing a schematic configuration of an air conditioning apparatus 250 according to Embodiment 3. The air conditioning apparatus 250 of Embodiment 3 is made up of an outdoor unit 260, an indoor unit 270, and refrigerant piping 280.

[0119] 26 and 27 are refrigerant circuit diagrams showing the flow of refrigerant in an air conditioner 250 according to Embodiment 3. Fig. 26 shows the flow during cooling operation, and Fig. 27 shows the flow during heating operation.

[0120] The outdoor unit 260 is composed of an outdoor heat exchanger 261 , an outdoor blower 262 , the compressor 60 according to the second embodiment, a four-way valve 263 , and an expansion valve 264 .

[0121] The indoor unit 270 is composed of an indoor heat exchanger 271 and an indoor blower 272 .

[0122] The outdoor heat exchanger 261 functions as a condenser during cooling operation and as an evaporator during heating operation. The indoor heat exchanger 271 functions as an evaporator during cooling operation and as a condenser during heating operation. The cooling operation and heating operation are switched by switching the flow path using the four-way valve 263.

[0123] The compressor 60 compresses the refrigerant that it draws in and discharges it.

[0124] The four-way valve 263 changes the flow direction of the refrigerant flowing through the refrigerant circuit. The expansion valve 264 reduces the pressure of the refrigerant to expand it.

[0125] The operation of the condenser will now be described. The air conditioning apparatus 250 condenses high-temperature, high-pressure refrigerant gas delivered from the compressor 60 into a condenser, where it exchanges heat with a medium (e.g., air) to condense the refrigerant gas and deliver it as low-temperature, high-pressure liquid refrigerant. Heat exchange with the medium occurs when the refrigerant flows into the condenser and passes between two fins in a direction perpendicular to the axial direction of the heat transfer tube. This allows heat to be released outside the condenser in an amount equal to the amount of heat lost from the refrigerant due to condensation.

[0126] During cooling operation, heat is radiated from the outdoor heat exchanger 261, which functions as a condenser, and warm air is expelled to the outside of the outdoor unit 260 by the outdoor blower 262. During heating operation, heat is radiated from the indoor heat exchanger 271, which functions as a condenser, and warm air is supplied indoors by the indoor blower 272.

[0127] The operation of the evaporator will now be described. The low-temperature gas-liquid mixed refrigerant delivered from the expansion valve 264 flows into the evaporator, where it exchanges heat with a medium (e.g., air), evaporating the gas-liquid mixed refrigerant and delivering it as low-temperature refrigerant gas. Heat exchange with the medium occurs when the refrigerant flows into the evaporator and passes between two fins in a direction perpendicular to the axial direction of the heat transfer tube. This cools the outside of the evaporator by the amount of heat added by the refrigerant due to evaporation.

[0128] During heating operation, the air is cooled by the outdoor heat exchanger 261, which functions as an evaporator, and the outdoor blower 262 blows cool air outside the outdoor unit 260. During cooling operation, the air is cooled by the indoor heat exchanger 271, which functions as an evaporator, and the indoor blower 272 supplies cool air into the room.

[0129] The refrigerant is a mixed refrigerant containing an ethylenic fluorohydrocarbon having a carbon-carbon double bond. By using a mixed refrigerant containing an ethylenic fluorohydrocarbon having a carbon-carbon double bond, the operating pressure of the compressor 60 is reduced, and a disproportionation reaction of the refrigerant can be prevented. In the third embodiment, the refrigerant is a mixed refrigerant containing R1123. Note that the refrigerant is not limited to R1123, and may be a mixed refrigerant containing another ethylenic fluorohydrocarbon.

[0130] The refrigerant may contain one or more ethylene-based fluorocarbons, and may be a mixed refrigerant made by mixing an ethylene-based fluorocarbon with another refrigerant. For example, the refrigerant may be a mixed refrigerant made by mixing R1123 and R32. The proportion of R1123 in this mixed refrigerant is preferably set within a range of 40 wt% to 60 wt%. By setting the proportion of R1123 within a range of 40 wt% to 60 wt%, a refrigerant with low global warming potential (GWP) and high refrigerant performance can be constructed. Note that R1123 is not limited to R32, and may be mixed with one or more of R1234yf, R1234ze(E), R1234ze(Z), R125, and R134a.

[0131] The refrigerant may also be a refrigerant containing two or more types of ethylenic fluorocarbons. For example, R1123 may be mixed with one or more of the ethylenic fluorocarbons R1141, R1132a, R1132(E), and R1132(Z). Furthermore, the refrigerant may be a mixed refrigerant of R516A, R445A, R444A, R454C, R444B, R454A, R455A, R457A, R459B, R452B, R454B, R447B, R447A, R446A, and R459A.

[0132] The refrigerant may also be any one of R1234yf, R1234ze, R32, and R290.

[0133] In the air conditioner 250 according to the third embodiment, the electric motor 1 described in the first embodiment is applied to the compressor 60, and therefore it is possible to obtain the same advantages as those described in the first embodiment. As a result, it is possible to provide a highly efficient air conditioner 250.

[0134] The electric motor 1 described in the first embodiment can be mounted on any electric device having a drive source, such as a machine tool, an electric vehicle, a drone, or a robot.

[0135] The features of the above-described embodiments and modifications can be combined with each other.

[0136] REFERENCE SIGNS LIST 1 electric motor, 2 stator, 3 rotor, 10 stator core, 13 slot, 20 winding, 21 first winding, 21a outer layer winding, 21b first inner and outer layer winding, 21c third inner and outer layer winding, 22 second winding, 22a inner layer winding, 22b second inner and outer layer winding, 22c fourth inner and outer layer winding, 50 rotor core, 51 magnet insertion hole, 58 permanent magnet, 60 compressor, 70 compression mechanism section, 211 coil end, 213 air gap section, 250 air conditioning device, C1 axis, C11 first circle, C12 second circle, C13 third circle, N neutral point.

Claims

1. A stator core constructed by laminating electrical steel sheets in the axial direction, The windings wound in a distributed winding on the stator core, Equipped with, The stator core has a plurality of slots in the circumferential direction, The winding has a first winding and a second winding, The first winding is configured such that the outer layer winding and the first inner and outer layer windings are connected in series. The second winding is formed by connecting the inner layer winding and the second inner and outer layer windings in series. In a plane perpendicular to the axial direction, when the circle passing through the outermost diameter portion of the slot in the radial direction with respect to the rotation axis of the stator core is defined as the first circle, the circle passing through the innermost diameter portion of the stator core in the radial direction with respect to the rotation axis of the stator core is defined as the second circle, and the circle that bisects the first circle and the second circle in the radial direction with respect to the rotation axis of the stator core is defined as the third circle, The outer layer winding is arranged across two slots, and in one slot and the other slot, either the radial center or the centroid of the outer layer winding is located on the outer diameter side of the third circle. The first inner and outer layer windings are arranged across two slots, with the radial center or centroid of the first inner and outer layer windings located on the outer diameter side of the third circle in one slot, and the radial center or centroid of the first inner and outer layer windings located on the inner diameter side of the third circle in the other slot. The inner layer winding is arranged across two slots, and in one slot and the other slot, either the radial center or the centroid of the inner layer winding is located on the inner side of the third circle. The second inner and outer layer windings are arranged across two slots, with either the radial center or the centroid of the second inner and outer layer windings located on the outer diameter side of the third circle in one slot, and either the radial center or the centroid of the second inner and outer layer windings located on the inner diameter side of the third circle in the other slot. The first winding and the second winding are connected in parallel. The winding method for the aforementioned winding is full winding. stator.

2. The first winding and the second winding are connected to the neutral point. The stator according to claim 1.

3. The aforementioned winding has three phases M and is configured in a Y-connection. The stator according to claim 1.

4. The winding has coil ends that extend radially to the outside of the axial end face of the stator core, The stator core has a gap between the axial end face and the coil end, The stator according to claim 1.

5. The aforementioned void portion has an axial height of 4 mm or more. The stator according to claim 4.

6. The aforementioned void portion has an axial height of 8 mm or less. The stator according to claim 4.

7. If the inductance of the first winding is L1 and the inductance of the second winding is L2, then 1.0 ≤ L1 / L2 ≤ 1.

046. The stator according to claim 1.

8. An electric motor comprising a stator and a rotor according to any one of claims 1 to 7, The rotor has a permanent magnet and a rotor core. The rotor core is constructed by laminating electromagnetic steel sheets in the axial direction, and is provided with magnet insertion holes. The magnet insertion holes are provided one or more times for each magnetic pole, and the permanent magnets are inserted to form magnetic poles with a number of poles P. Electric motor.

9. The total number of slots S, the number of phases M, and the number of poles P are such that S / (MP) = 1. The electric motor according to claim 8.

10. The winding coefficient Kw of the aforementioned winding is Kw = 1. The electric motor according to claim 8.

11. The aforementioned number of poles P is P = 6, The total number of slots S is S = 18. The electric motor according to claim 8.

12. The first winding further comprises a third inner / outer layer winding connected in series with the first inner / outer layer winding. The second winding further comprises a fourth inner and outer layer winding connected in series with the second inner and outer layer winding. The third inner and outer layer winding is arranged across two slots, with either the radial center or the center of gravity of the third inner and outer layer winding located on the outer diameter side of the third circle in one slot, and either the radial center or the center of gravity of the third inner and outer layer winding located on the inner diameter side of the third circle in the other slot. The fourth inner and outer layer winding is arranged across two slots, such that in one slot, either the radial center or the centroid of the fourth inner and outer layer winding is located on the outer diameter side of the third circle, and in the other slot, either the radial center or the centroid of the fourth inner and outer layer winding is located on the inner diameter side of the third circle. The electric motor according to claim 11.

13. The aforementioned permanent magnet is a rare-earth magnet. The electric motor according to claim 8.

14. The electric motor according to claim 8, A compression mechanism driven by the aforementioned electric motor, Equipped with, Compressor.

15. The compressor, condenser, pressure reducing device, and evaporator according to claim 14, Equipped with, Air conditioning system.