JP6824333B2 - Electric motors, rotors, compressors and refrigeration and air conditioners - Google Patents

Description

The present invention relates to a permanent magnet embedded electric motor and its rotor, and a compressor and a refrigerating air conditioner using the electric motor.

Conventionally, an electric motor in which a permanent magnet is attached to a rotor has been known. This type of motor is roughly divided into a surface magnet type motor in which a permanent magnet is attached to the surface of the rotor (see, for example, Patent Document 1) and a permanent magnet embedded type motor in which a permanent magnet is embedded inside the rotor. Will be done. In the permanent magnet embedded type electric motor, a magnet insertion hole is formed in the rotor core, and the permanent magnet is arranged in the magnet insertion hole. The magnet insertion hole is provided with a magnet holding portion (projection) for positioning the permanent magnet so that it does not move in the magnet insertion hole.

JP-A-6-70520 (see FIG. 2)

However, since the magnet holding portion is made of the same magnetic material as the rotor core, the magnetic flux from the stator tends to flow to the magnet holding portion when the electric motor is driven. Therefore, the end portion of the permanent magnet adjacent to the magnet holding portion is likely to be demagnetized.

The present invention has been made to solve the above problems, and an object of the present invention is to suppress demagnetization of a permanent magnet.

The electric motor of the present invention includes a stator and a rotor arranged inside the stator. The rotor has a rotor core having a magnet insertion hole and two adjacent permanent magnets arranged in the magnet insertion hole of the rotor core. The magnet insertion hole is continuously formed in a V shape in which the central portion in the circumferential direction of the rotor core projects inward in the radial direction of the rotor core . The rotor core includes a first magnet holding portion arranged between two adjacent permanent magnets in the magnet insertion hole and a second magnet holding portion arranged at the end of the magnet insertion hole in the circumferential direction of the rotor core. Has. The first magnet holding portion and the second magnet holding portion are protrusions formed in the magnet insertion hole, and a gap is formed in the magnet insertion hole on the outer side in the radial direction of the protrusion. The rotor core is formed by laminating a plurality of electromagnetic steel plates in the axial direction. Let A be the number of the plurality of electrical steel sheets of the rotor core, let B be the number of electrical steel sheets having the first magnet holding portion, and be the number of electrical steel sheets having the second magnet holding portion among the plurality of electrical steel sheets of the rotor core. When C is set, the relationship of A> B and A> C is established.

The rotor of the present invention has a rotor core having a magnet insertion hole and two adjacent permanent magnets arranged in the magnet insertion hole of the rotor core. The magnet insertion hole has a V-shape in which the central portion in the circumferential direction of the rotor core projects inward in the radial direction of the rotor core. The rotor core includes a first magnet holding portion arranged between two adjacent permanent magnets in the magnet insertion hole and a second magnet holding portion arranged at the end of the magnet insertion hole in the circumferential direction of the rotor core. Has. The rotor core is formed by laminating a plurality of electromagnetic steel plates in the axial direction. Let A be the number of the plurality of electrical steel sheets of the rotor core, let B be the number of electrical steel sheets having the first magnet holding portion, and be the number of the electrical steel sheets having the second magnet holding portion among the plurality of electrical steel sheets of the rotor core. When C is set, the relationship of A> B and A> C is established.

The compressor of the present invention includes an electric motor and a compression mechanism driven by the electric motor. The electric motor includes a stator and a rotor arranged inside the stator. The rotor has a rotor core having a magnet insertion hole and two adjacent permanent magnets arranged in the magnet insertion hole of the rotor core. The magnet insertion hole has a V-shape in which the central portion in the circumferential direction of the rotor core projects inward in the radial direction of the rotor core. The rotor core includes a first magnet holding portion arranged between two adjacent permanent magnets in the magnet insertion hole and a second magnet holding portion arranged at the end of the magnet insertion hole in the circumferential direction of the rotor core. Has. The rotor core is formed by laminating a plurality of electromagnetic steel plates in the axial direction. Let A be the number of the plurality of electrical steel sheets of the rotor core, let B be the number of electrical steel sheets having the first magnet holding portion, and be the number of the electrical steel sheets having the second magnet holding portion among the plurality of electrical steel sheets of the rotor core. When C is set, the relationship of A> B and A> C is established.

The refrigeration and air conditioner of the present invention includes a compressor, a condenser, a decompression device and an evaporator. The compressor includes an electric motor and a compression mechanism driven by the electric motor. The electric motor includes a stator and a rotor arranged inside the stator. The rotor has a rotor core having a magnet insertion hole and two adjacent permanent magnets arranged in the magnet insertion hole of the rotor core. The magnet insertion hole has a V-shape in which the central portion in the circumferential direction of the rotor core projects inward in the radial direction of the rotor core. The rotor core includes a first magnet holding portion arranged between two adjacent permanent magnets in the magnet insertion hole and a second magnet holding portion arranged at the end of the magnet insertion hole in the circumferential direction of the rotor core. Has. The rotor core is formed by laminating a plurality of electromagnetic steel plates in the axial direction. Let A be the number of the plurality of electrical steel sheets of the rotor core, let B be the number of electrical steel sheets having the first magnet holding portion, and be the number of the electrical steel sheets having the second magnet holding portion among the plurality of electrical steel sheets of the rotor core. When C is set, the relationship of A> B and A> C is established.

According to the present invention, among a plurality of electrical steel sheets constituting the rotor core, the number B of the electrical steel sheets having a first magnet holding portion between adjacent permanent magnets in the V-shaped magnet insertion hole, and the circumferential direction. The number C of the electrical steel sheets having the second magnet holding portion at the end of the magnet insertion hole in the above is smaller than the total number A of the electrical steel sheets. Therefore, demagnetization of the permanent magnet due to the magnetic flux flowing from the first magnet holding portion and the second magnet holding portion to the permanent magnet can be suppressed. Further, the permanent magnet can be positioned in the magnet insertion hole by the first magnet holding portion and the second magnet holding portion provided on some of the electromagnetic steel sheets.

It is sectional drawing of the electric motor of Embodiment 1. FIG. It is sectional drawing of the rotor which shows the 1st electrical steel sheet of Embodiment 1 in plan view. It is sectional drawing of the rotor core which shows the 1st electrical steel sheet of Embodiment 1 in plan view. It is sectional drawing of the rotor which shows the 2nd electrical steel sheet of Embodiment 1 in plan view. It is sectional drawing of the rotor core which shows the 2nd magnetic steel sheet of Embodiment 1 in plan view. It is a figure which shows the laminated structure of the rotor core of Embodiment 1. FIG. It is a figure which shows another example of the laminated structure of the rotor core of Embodiment 1. FIG. It is sectional drawing of the compressor of Embodiment 1. FIG. It is a figure of the refrigerating air conditioner of Embodiment 1. It is sectional drawing of the rotor which shows the 3rd magnetic steel sheet of Embodiment 2 in plan view. It is sectional drawing of the rotor core which shows the 3rd magnetic steel sheet of Embodiment 2 in plan view. It is a figure which shows the laminated structure of the rotor core of Embodiment 2. It is a graph which shows the change of the demagnetization rate of the electric motor of Embodiment 2 and the electric motor of a comparative example. It is sectional drawing of the rotor which shows the 4th electromagnetic steel plate of the modification in plan view. It is sectional drawing of the rotor core which shows the 4th electromagnetic steel plate of the modification in plan view. It is sectional drawing of the rotor which shows the 5th electromagnetic steel plate of another modification in plan view. It is sectional drawing of the rotor core which shows the 5th electromagnetic steel plate of another modification in plan view. It is sectional drawing of the rotor which shows the 1st electrical steel sheet of Embodiment 3 in plan view. It is sectional drawing of the rotor core which shows the 1st electrical steel sheet of Embodiment 3 in a plan view. It is sectional drawing of the rotor which shows the 2nd electrical steel sheet of Embodiment 3 in plan view. It is sectional drawing of the rotor core which shows the 2nd magnetic steel sheet of Embodiment 3 in plan view. It is sectional drawing of the rotor which shows the 1st electrical steel sheet of Embodiment 4 in a plan view. It is sectional drawing of the rotor core which shows the 1st electrical steel sheet of Embodiment 4 in a plan view. It is sectional drawing of the rotor which shows the 2nd electrical steel sheet of Embodiment 4 in a plan view. It is sectional drawing of the rotor core which shows the 2nd magnetic steel sheet of Embodiment 4 in a plan view. It is sectional drawing of the rotor core which shows the 1st electrical steel sheet of Embodiment 5. It is sectional drawing of the rotor core which shows the 2nd electromagnetic steel plate of Embodiment 5.

Embodiment 1.
First, Embodiment 1 of the present invention will be described. The first embodiment is intended to position the permanent magnet in the magnet insertion hole of the rotor and suppress the demagnetization of the permanent magnet in the permanent magnet embedded type electric motor.

FIG. 1 is a cross-sectional view showing the configuration of the electric motor 100 according to the first embodiment of the present invention. The electric motor 100 is a permanent magnet-embedded electric motor in which a permanent magnet 40 is embedded in a rotor 2, and is used, for example, in a rotary compressor 300 (see FIG. 8). Note that FIG. 1 is a cross-sectional view of a plane orthogonal to the rotation axis of the rotor 2.

As shown in FIG. 1, the electric motor 100 includes a stator 1 and a rotor 2 rotatably provided inside the stator 1. An air gap of, for example, 0.3 to 1 mm is formed between the stator 1 and the rotor 2.

The stator 1 includes a stator core 10 and a coil 15 (FIG. 8) wound around the stator core 10. The stator core 10 is formed by laminating a plurality of electromagnetic steel plates having a thickness of 0.1 to 0.7 mm (here, 0.35 mm) in the direction of the rotation axis and fastening them by caulking.

The stator core 10 has an annular yoke portion 11 and a plurality of (here, nine) teeth 12 projecting radially inward from the yoke portion 11. Slots are formed between adjacent teeth 12. Each tooth 12 has a tooth tip portion 13 having a wide width (dimension in the circumferential direction of the stator core 10) at the tip inside in the radial direction.

A coil 15 (FIG. 8), which is a stator winding, is wound around each tooth 12. The coil 15 is formed by winding a magnet wire around a tooth 12 via an insulator 16 (FIG. 8). Further, the coil 15 is formed by Y-connecting three phases (U phase, V phase and W phase).

The stator core 10 has a configuration in which a plurality of blocks (nine in this case) for each tooth 12 are connected via a thin portion. With the stator core 10 unfolded in a strip shape, a magnet wire (coil 15) having a diameter of 1.0 mm is wound around each tooth 12 for, for example, 80 turns, and then the stator core 10 is bent in an annular shape to weld both ends. The stator core 10 is not limited to one having a configuration in which a plurality of blocks are connected in this way.

Next, the configuration of the rotor 2 will be described. The rotor 2 has a rotor core 20 and a permanent magnet 40 attached to the rotor core 20. The rotor core 20 is formed by laminating a plurality of electromagnetic steel plates having a thickness of 0.1 to 0.7 mm (here, 0.35 mm) in the direction of the rotation axis and fastening them by caulking. Here, the rotor core 20 is configured by laminating two types of electrical steel sheets, that is, a first electrical steel sheet 201 (FIGS. 2 to 3) and a second electrical steel sheet 202 (FIGS. 4 to 5).

FIG. 2 is a cross-sectional view of the rotor 2 showing the first electromagnetic steel plate 201 in a plan view. The rotor core 20 has a cylindrical shape, and a shaft hole 21 (center hole) is formed at the center in the radial direction thereof. A shaft serving as a rotation shaft of the rotor 2 (for example, the shaft 315 of the rotary compressor 300 shown in FIG. 8) is fixed to the shaft hole 21 by shrink fitting or press fitting.

Hereinafter, the direction along the outer circumference (circumference) of the rotor core 20 is simply referred to as "circumferential direction". Further, the axial direction (direction of the rotation axis) of the rotor core 20 is simply referred to as "axial direction". Further, the radial direction of the rotor core 20 is simply referred to as "diameter direction".

Along the outer peripheral surface of the rotor core 20, a plurality of (here, six) magnet insertion holes 22 into which the permanent magnets 40 are inserted are formed. The magnet insertion hole 22 is a gap, and one magnet insertion hole 22 corresponds to one magnetic pole. Since six magnet insertion holes 22 are provided here, the rotor 2 as a whole has six poles. The number of poles is not limited to 6 poles, and may be 2 poles or more. Further, the space between the adjacent magnet insertion holes 22 is between the poles.

Two permanent magnets 40 are arranged in one magnet insertion hole 22. That is, two permanent magnets 40 are arranged for one magnetic pole. Here, since the rotor 2 has 6 poles as described above, a total of 12 permanent magnets 40 are arranged.

The permanent magnet 40 is a flat plate-shaped member that is long in the axial direction of the rotor core 20, has a width in the circumferential direction of the rotor core 20, and has a thickness in the radial direction. The thickness of the permanent magnet 40 is, for example, 2 mm. The permanent magnet 40 is composed of, for example, a rare earth magnet containing neodymium (Nd), iron (Fe) and boron (B) as main components, which will be described later.

The permanent magnet 40 is magnetized in the thickness direction. Further, the two permanent magnets 40 arranged in one magnet insertion hole 22 are magnetized so that the same magnetic poles face the same side in the radial direction. For example, the two permanent magnets 40 arranged in a certain magnet insertion hole 22 are magnetized so that the inner side in the radial direction is the north pole and the outer side in the radial direction is the south pole.

Next, the configuration of the rotor core 20 will be described. FIG. 3 is a cross-sectional view of the rotor core 20 showing the first electromagnetic steel plate 201 in a plan view. The magnet insertion holes 22 are evenly arranged in the circumferential direction of the rotor core 20. Further, each magnet insertion hole 22 has a V-shape in which the central portion in the circumferential direction protrudes inward in the radial direction.

Further, the magnet insertion hole 22 has a first portion 22a and a second portion 22b on both sides of a central portion (a portion forming a V-shaped apex) in the circumferential direction. The first portion 22a and the second portion 22b of the magnet insertion hole 22 extend linearly, respectively, and a permanent magnet 40 (FIG. 2) is inserted into each.

That is, two permanent magnets 40 are arranged in a V shape on one magnetic pole of the rotor 2. By arranging in this way, the electric resistance of the permanent magnets can be increased and the in-plane eddy current loss can be reduced as compared with the case where one permanent magnet 40 is arranged on one magnetic pole. As a result, the loss during driving of the electric motor 100 can be reduced, and the efficiency of the electric motor 100 can be improved.

Flux barriers 24 are formed on both sides of the magnet insertion hole 22 in the circumferential direction. The flux barrier 24 is a gap continuously formed in the magnet insertion hole 22. The flux barrier 24 is for suppressing the leakage flux between adjacent magnetic poles (that is, the magnetic flux flowing through the poles).

The region between the outer circumference of the rotor core 20 and the flux barrier 24 is formed so that the magnetic path is narrowed so that the magnetic flux is not short-circuited between the permanent magnets 40 of the adjacent magnetic poles. Here, the distance between the outer circumference of the rotor core 20 and the flux barrier 24 is set to be the same as the thickness of the electromagnetic steel plate constituting the rotor core 20 (for example, 0.35 mm).

The rotor core 20 has a first magnet holding portion 31 which is a protrusion at a central portion (central portion in the circumferential direction) of the magnet insertion hole 22 in the circumferential direction. The first magnet holding portion 31 is arranged between two permanent magnets 40 (FIG. 2) adjacent to each other in the magnet insertion hole 22.

The first magnet holding portion 31 is formed so as to project toward the inside of the permanent magnet 40 with respect to the plate surface (flat surface) of the permanent magnet 40 in the thickness direction of the permanent magnet 40. In other words, the first magnet holding portion 31 is formed so as to be able to abut against the end faces of the two permanent magnets 40 facing each other.

Further, the rotor core 20 has second magnet holding portions 32, which are protrusions, at both ends (circumferential end portions) of the magnet insertion hole 22 in the circumferential direction. The second magnet holding portion 32 is arranged outside the two permanent magnets 40 (FIG. 2) adjacent to each other in the magnet insertion hole 22 in the circumferential direction.

The second magnet holding portion 32 is formed so as to project toward the inside of the permanent magnet 40 with respect to the plate surface (flat surface) of the permanent magnet 40 in the thickness direction of the permanent magnet 40. In other words, each of the second magnet holding portions 32 is formed so as to be in contact with each end surface of the two permanent magnets 40 on the sides separated from each other.

The width of the magnet insertion hole 22 (dimension in the thickness direction of the permanent magnet 40) is set to a width that allows the permanent magnet 40 to be held without rattling. Further, assuming that the thickness of the permanent magnet 40 is 2 mm, the amount of protrusion of the magnet holding portions 31 and 32 in the thickness direction of the permanent magnet 40 is set to, for example, 0.5 mm.

The magnet holding portions 31 and 32 are formed as a part of the rotor core 20, and position (position restrict) the permanent magnet 40 so as not to move in the circumferential direction in the magnet insertion hole 22. When the electric motor 100 is driven, an electromagnetic force is generated in the direction of moving the permanent magnet 40 in the magnet insertion hole 22 by the action of the magnetic flux generated from the coil 15 of the stator 1 and the permanent magnet 40. By providing the magnet holding portions 31 and 32, the movement of the permanent magnet 40 can be suppressed, and the generation of vibration noise accompanying the movement of the permanent magnet 40 can be suppressed.

Another configuration for positioning the permanent magnet 40 in the magnet insertion hole 22 is to provide a bridge portion at the center of the magnet insertion hole 22 in the circumferential direction to divide the magnet insertion hole 22 into two. However, since the bridge portion is made of a magnetic material, for example, a short circuit occurs in which the magnetic flux emitted from the north pole of the permanent magnet 40 flows through the bridge portion to the south pole of the same permanent magnet 40. Such a short circuit of magnetic flux causes a decrease in magnet torque.

On the other hand, by arranging a plurality of permanent magnets 40 in the magnet insertion hole 22 and adopting a configuration in which the protruding magnet holding portions 31 and 32 are provided, a short circuit of magnetic flux as in the case where a bridge portion is provided is adopted. Can be suppressed, and a decrease in magnet torque can be suppressed.

Here, the opposite sides of the two permanent magnets 40 are positioned by one first magnet holding portion 31 provided at the central portion in the circumferential direction of the magnet insertion hole 22. However, two first magnet holding portions 31 may be provided at the central portion in the circumferential direction of the magnet insertion hole 22, and each of them may position the permanent magnet 40.

The magnet holding portions 31 and 32 are formed inside the magnet insertion hole 22 in the radial direction. That is, a gap is formed on the radial outer side of the magnet holding portions 31 and 32. The magnet holding portions 31 and 32 are formed inside the magnet insertion hole 22 instead of outside in the radial direction in order to enhance the effect of suppressing demagnetization of the permanent magnet 40.

Here, the demagnetization of the permanent magnet 40 will be described. When the electric motor 100 is driven, the magnetic flux generated by the coil 15 of the stator 1 passes through the outer peripheral side of the permanent magnet 40 of the rotor core 20 to generate a magnetic attraction force, and a rotational torque to rotate the rotor 2 is generated.

When the current flowing through the coil 15 of the stator 1 is large, or when the current phase is changed, the magnetic flux generated by the coil 15 may act in the direction of canceling the magnetization of the permanent magnet 40. Then, when the value of the current flowing through the coil 15 exceeds the threshold value, a phenomenon called demagnetization occurs in which the magnetization of the permanent magnet 40 is reversed and cannot be restored.

When the magnet holding portions 31 and 32 are provided on the radial outer side of the magnet insertion hole 22, since the magnet holding portions 31 and 32 are made of a magnetic material, they are integrated with the radial outer region of the magnet insertion hole 22 in the rotor core 20. It becomes easy to form a magnetic path. Since this region is a region in which the magnetic flux generated by the coil 15 is particularly easy to flow, the end portion of the permanent magnet 40 adjacent to the magnet holding portions 31 and 32 is likely to be demagnetized.

Therefore, the magnet holding portions 31 and 32 are arranged inside the magnet insertion hole 22 instead of outside in the radial direction. When arranged in this way, a gap (that is, a gap inside the magnet insertion hole 22) is formed between the region radially outside the magnet insertion hole 22 in the rotor core 20 and the magnet holding portions 31 and 32. Therefore, the magnetic flux generated by the coil 15 is less likely to flow to the magnet holding portions 31 and 32, and the permanent magnet 40 is less likely to be demagnetized.

However, the inside of the magnet insertion hole 22 is a void, and the magnetic resistance is very large. In the magnet insertion hole 22, the portion where the magnet holding portions 31 and 32 are provided is a portion where the magnetic resistance is locally small. Therefore, when the current flowing through the coil 15 becomes large, the magnetic flux generated by the coil 15 may flow through the magnet holding portions 31 and 32, and the end portion of the permanent magnet 40 adjacent to the magnet holding portions 31 and 32 can be demagnetized. There is sex.

Therefore, in the first embodiment, the rotor core 20 is configured by laminating two types of electrical steel sheets (the first electrical steel sheet 201 and the second electrical steel sheet 202). As shown in FIG. 3, the first magnetic steel sheet 201 has a first magnet holding portion 31 at the central portion in the circumferential direction of the magnet insertion hole 22, and further, a first magnet holding portion 31 is provided at the circumferential end portion of the magnet insertion hole 22. It has 2 magnet holding portions 32.

FIG. 4 is a cross-sectional view of the rotor 2 showing the second electromagnetic steel plate 202 in a plan view. FIG. 5 is a cross-sectional view of the rotor core 20 showing the second electromagnetic steel plate 202 in a plan view.

Like the first electrical steel sheet 201, the second electrical steel sheet 202 has a plurality of (here, six) magnet insertion holes 22. The magnet insertion hole 22 has a V-shape in which the central portion in the circumferential direction protrudes inward in the radial direction, and two permanent magnets 40 are arranged in one magnet insertion hole 22. However, the magnet insertion holes 22 of the second magnetic steel sheet 202 are not provided with the magnet holding portions 31 and 32.

FIG. 6 is a diagram showing a laminated structure of the rotor core 20. The rotor core 20 has N1 first electrical steel sheet 201, N2 second electrical steel sheet 202, and N3 first electrical steel sheet 201, N4 in the direction of its rotation axis in order from the top shown in FIG. It is a stack of two second electrical steel sheets 202 and N5 first electrical steel sheets 201. That is, the first electromagnetic steel plate 201 is arranged at both ends and the center of the rotor core 20 in the rotation axis direction (lamination direction).

The total number A of the electromagnetic steel sheets constituting the rotor core 20 is N1 + N2 + N3 + N4 + N5. On the other hand, among the electromagnetic steel sheets constituting the rotor core 20, the number B of the electromagnetic steel sheets (first electromagnetic steel sheet 201) having the first magnet holding portion 31 between the permanent magnets 40 adjacent to each other in the magnet insertion hole 22 is It is N1 + N3 + N5. Further, the number C of the electromagnetic steel sheets (first electromagnetic steel sheet 201) having the second magnet holding portion 32 at the circumferential end of the magnet insertion hole 22 is also N1 + N3 + N5.

That is, the total number A of the electromagnetic steel sheets constituting the rotor core 20 and the number B of the electromagnetic steel sheets (first electromagnetic steel sheet 201) having the first magnet holding portion 31 between the permanent magnets 40 adjacent to each other in the magnet insertion hole 22. And the number C of the electrical steel sheet (first electrical steel sheet 201) having the second magnet holding portion 32 at the circumferential end of the magnet insertion hole 22 satisfies the relationship of A> B, A> C.

In the first embodiment, the permanent magnet 40 can be positioned in the magnet insertion hole 22 by the magnet holding portions 31 and 32 provided on the first electromagnetic steel plate 201 of the rotor core 20. Further, since the second electromagnetic steel plate 202 of the rotor core 20 is not provided with the magnet holding portions 31 and 32, even when the current flowing through the coil 15 of the stator 1 becomes large, the magnet holding portions 31 and 32 It is possible to suppress demagnetization of the permanent magnet 40 due to the magnetic flux flowing through the permanent magnet 40.

As described above, in the first embodiment, the total number A of the electromagnetic steel sheets constituting the rotor core 20, the number B of the electrical steel sheets having the first magnet holding portion 31 (the first electrical steel sheet 201), and the second By satisfying the relationship of A> B and A> C with the number C of the electromagnetic steel sheet (first electromagnetic steel sheet 201) having the magnet holding portion 32, the permanent magnet 40 is positioned in the magnet insertion hole 22. Moreover, the demagnetization of the permanent magnet 40 can be suppressed.

In particular, by arranging the first electromagnetic steel plate 201 at at least one end in the rotation axis direction of the rotor core 20, when the permanent magnet 40 is inserted into the magnet insertion hole 22, the magnet holding portions 31 and 32 guide the permanent magnet 40. Functions as. Therefore, the work of inserting the permanent magnet 40 becomes easy.

Further, by arranging the first electromagnetic steel sheets 201 at both ends and the center of the rotor core 20 in the rotation axis direction, the permanent magnets 40 are spaced apart in the longitudinal direction (rotation axis direction of the rotor core 20). It is held by the magnet holding portions 31 and 32 of the electromagnetic steel plate 201. Therefore, the inclination of the permanent magnet 40 in the magnet insertion hole 22 can be effectively suppressed.

The laminated structure of the rotor core 20 is not limited to the laminated structure shown in FIG. For example, as shown in FIG. 7, the first electromagnetic steel plate 201 may be laminated on both ends of the rotor core 20 in the rotation axis direction, and the second electromagnetic steel plate 202 may be laminated on the other portions. Even with such a laminated structure, the permanent magnet 40 can be positioned in the magnet insertion hole 22 and demagnetization of the permanent magnet 40 can be suppressed.

Next, the configuration of the permanent magnet 40 will be described. As described above, the permanent magnet 40 is composed of a rare earth magnet containing neodymium (Nd), iron (Fe) and boron (B) as main components, and does not contain dysprosium (Dy). The residual magnetic flux density of the permanent magnet 40 at 20 ° C. is 1.27 to 1.42 T, and the coercive force at 20 ° C. is 1671 to 1922 kA / m.

Rare earth magnets containing neodymium, iron and boron as main components have the property that the coercive force decreases as the temperature rises, and the rate of decrease is -0.5 to -0.6% / K. When the electric motor 100 is used as a compressor, it is used in a high temperature atmosphere of 100 to 150 ° C. In this case, the electric motor 100 is used at a temperature about 130 ° C. higher than room temperature (20 ° C.). Therefore, assuming that the rate of decrease in the coercive force of the permanent magnet 40 is −0.5% / K, at 150 ° C. The coercive force will be reduced by 65%. Therefore, in general, dysprosium is added to the permanent magnet to improve the coercive force. The coercive force increases in proportion to the dysprosium content.

A coercive force of about 1100 to 1500 A / m is required to prevent demagnetization of the permanent magnet when the maximum load assumed on the compressor is applied. In order to secure this coercive force at an atmospheric temperature of 150 ° C., it is necessary to design the coercive force at room temperature (20 ° C.) to be 1800 to 2300 A / m.

Rare earth magnets containing neodymium, iron and boron as main components have a coercive force of about 1800 A / m at room temperature in a state where dysprosium is not added. Therefore, in order to obtain a coercive force of 2300 A / m, it was necessary to add 2% by weight of dysprosium. On the other hand, dysprosium is known to have unstable prices and carry procurement risks.

Further, when dysprosium is added to the permanent magnet, the residual magnetic flux density decreases. When the residual magnetic flux density decreases, the magnet torque of the motor decreases, and the current required to obtain the desired output increases. That is, the copper loss increases and the efficiency of the motor decreases. For these reasons, it is required to reduce the amount of dysprosium added.

Therefore, the permanent magnet 40 used in the first embodiment is composed of a rare earth magnet containing neodymium, iron and boron as main components, and does not contain dysprosium. Rare earth magnets containing no dysprosium (mainly composed of neodymium, iron and boron) have a residual magnetic flux density of 1.27 to 1.42 T at 20 ° C and a coercive force at 20 ° C. Is 1671 to 1922 kA / m.

In the first embodiment, the rotor 2 has a structure in which the above-mentioned first electromagnetic steel sheet 201 and the second electrical steel sheet 202 are laminated to suppress demagnetization of the permanent magnet 40. Therefore, even if the permanent magnet 40 does not contain dysprosium (the residual magnetic flux density at 20 ° C is 1.27 to 1.42 T and the coercive force at 20 ° C is 1671 to 1922 kA / m), it is demagnetized. Can be suppressed. In addition, since it is possible to avoid a decrease in the residual magnetic flux density due to the addition of dysprosium, it is possible to reduce the current value required to obtain the same torque. As a result, copper loss can be reduced and the efficiency of the electric motor can be improved.

Next, the rotary compressor 300 using the electric motor 100 will be described. FIG. 8 is a cross-sectional view showing the configuration of the rotary compressor 300. The rotary compressor 300 includes a frame 301, a compression mechanism 310 arranged in the frame 301, and an electric motor 100 for driving the compression mechanism 310.

The compression mechanism 310 includes a cylinder 311 having a cylinder chamber 312, a shaft 315 rotated by an electric motor 100, a rolling piston 314 fixed to the shaft 315, and a vane that divides the inside of the cylinder chamber 312 into a suction side and a compression side (shown). , And an upper frame 316 and a lower frame 317 into which the shaft 315 is inserted to close the axial end face of the cylinder chamber 312. An upper discharge muffler 318 and a lower discharge muffler 319 are mounted on the upper frame 316 and the lower frame 317, respectively.

The frame 301 is, for example, a cylindrical container formed by drawing a steel plate having a thickness of 3 mm. Refrigerating machine oil (not shown) that lubricates each sliding portion of the compression mechanism 310 is stored in the bottom of the frame 301. The shaft 315 is rotatably held by the upper frame 316 and the lower frame 317.

The cylinder 311 includes a cylinder chamber 312 inside. The rolling piston 314 rotates eccentrically in the cylinder chamber 312. The shaft 315 has an eccentric shaft portion, and a rolling piston 314 is fitted to the eccentric shaft portion.

The stator core 10 of the electric motor 100 is attached to the inside of the frame 301 by shrink fitting. Power is supplied to the coil 15 wound around the stator core 10 from the glass terminal 305 fixed to the frame 301. A shaft 315 is fixed to the shaft hole 21 (FIG. 1) of the rotor 2.

An accumulator 302 for storing the refrigerant gas is attached to the outside of the frame 301. A suction pipe 303 is fixed to the frame 301, and refrigerant gas is supplied from the accumulator 302 to the cylinder 311 via the suction pipe 303. Further, a discharge pipe 307 for discharging the refrigerant to the outside is provided on the upper part of the frame 301.

As the refrigerant, for example, R410A, R407C, R22 or the like can be used. From the viewpoint of preventing global warming, it is desirable to use a refrigerant having a low GWP (global warming potential). As the low GWP refrigerant, for example, the following refrigerants can be used.

(1) First, a halogenated hydrocarbon having a carbon double bond in the composition, for example, HFO (Hydro-Fluoro-Orefin) -1234yf (CF3CF = CH2) can be used. The GWP of HFO-1234yf is 4.
(2) Further, a hydrocarbon having a carbon double bond in the composition, for example, R1270 (propylene) may be used. The GWP of R1270 is 3, which is lower than HFO-1234yf but higher in flammability than HFO-1234yf.
(3) Also, a mixture containing at least one of a halogenated hydrocarbon having a carbon double bond in the composition or a hydrocarbon having a carbon double bond in the composition, for example, a mixture of HFO-1234yf and R32. You may use it. Since the above-mentioned HFO-1234yf is a low-pressure refrigerant, the pressure loss tends to be large, which may lead to deterioration of the performance of the refrigeration cycle (particularly the evaporator). Therefore, it is practically desirable to use a mixture with R32 or R41, which is a higher pressure refrigerant than HFO-1234yf.

The operation of the rotary compressor 300 is as follows. The refrigerant gas supplied from the accumulator 302 is supplied into the cylinder chamber 312 of the cylinder 311 through the suction pipe 303. When the electric motor 100 is driven and the rotor 2 rotates, the shaft 315 rotates together with the rotor 2. Then, the rolling piston 314 fitted to the shaft 315 rotates eccentrically in the cylinder chamber 312, and the refrigerant is compressed in the cylinder chamber 312. The compressed refrigerant passes through the discharge mufflers 318 and 319, and further rises in the frame 301 through the air holes (not shown) provided in the electric motor 100, and is discharged from the discharge pipe 307.

Next, the refrigerating and air-conditioning apparatus 400 of the first embodiment will be described. FIG. 9 is a diagram showing the configuration of the refrigerating air conditioner 400 of the first embodiment. The refrigerating and air-conditioning device 400 shown in FIG. 9 includes a compressor 401, a condenser 402, a throttle device (expansion valve) 403, and an evaporator 404. The compressor 401, the condenser 402, the throttle device 403 and the evaporator 404 are connected by a refrigerant pipe 407 to form a refrigeration cycle. That is, the refrigerant circulates in the order of the compressor 401, the condenser 402, the drawing device 403, and the evaporator 404.

The compressor 401, the condenser 402, and the drawing device 403 are provided in the outdoor unit 410. The compressor 401 is composed of the rotary compressor 300 shown in FIG. The outdoor unit 410 is provided with an outdoor blower 405 that supplies outdoor air to the condenser 402. The evaporator 404 is provided in the indoor unit 420. The indoor unit 420 is provided with an indoor blower 406 that supplies indoor air to the evaporator 404.

The operation of the refrigerating air conditioner 400 is as follows. The compressor 401 compresses and sends out the sucked refrigerant. The condenser 402 exchanges heat between the refrigerant flowing in from the compressor 401 and the outdoor air, condenses the refrigerant, liquefies it, and sends it out to the refrigerant pipe 407. The outdoor blower 405 supplies outdoor air to the condenser 402. The throttle device 403 adjusts the pressure of the refrigerant flowing through the refrigerant pipe 407 by changing the opening degree.

The evaporator 404 exchanges heat between the refrigerant reduced to a low pressure by the throttle device 403 and the air in the room, causes the refrigerant to take heat of the air, evaporate (vaporize) it, and send it to the refrigerant pipe 407. The indoor blower 406 supplies the indoor air to the evaporator 404. As a result, the cold air whose heat has been taken away by the evaporator 404 is supplied to the room.

The compressor 401 of the refrigerating air conditioner 400 is used in a high temperature atmosphere, and causes a large load fluctuation during compression. At high temperatures, the coercive force of the permanent magnet 40 tends to decrease, and the fluctuation of the current flowing through the coil 15 also increases due to load fluctuations. Since the electric motor 100 of the first embodiment has a configuration that suppresses the demagnetization of the permanent magnet 40 as described above, it is suitable for use in the compressor 401 of such a refrigerating air conditioner 400.

As described above, according to the first embodiment of the present invention, the total number A of the electrical steel sheets constituting the rotor core 20 and the number of the electrical steel sheets having the first magnet holding portion 31 (the first electrical steel sheet 201). B and the number C of the electrical steel sheets (first electrical steel sheet 201) having the second magnet holding portion 32 are configured to satisfy A> B and A> C. As a result, the permanent magnet 40 can be positioned in the magnet insertion hole 22, and demagnetization of the permanent magnet 40 due to the magnetic flux passing through the magnet holding portions 31 and 32 can be suppressed. Further, by suppressing the demagnetization of the permanent magnet 40 in this way, the performance deterioration of the electric motor 100 is suppressed, and stable drive control becomes possible.

Further, the magnet holding portions 31 and 32 are formed so as to project toward the inside of the permanent magnet 40 with respect to the plate surface of the permanent magnet 40 in the thickness direction of the permanent magnet 40. Therefore, the permanent magnet 40 can be effectively positioned in the magnet insertion hole 22.

Further, the magnet holding portions 31 and 32 are arranged inside the rotor core 20 in the radial direction in the magnet insertion hole 22. Therefore, the magnetic flux generated by the coil 15 of the stator 1 is less likely to flow to the magnet holding portions 31 and 32, and demagnetization of the permanent magnet 40 due to the magnetic flux flowing through the magnet holding portions 31 and 32 can be suppressed.

Further, the number B of the electromagnetic steel plate (first electromagnetic steel plate 201) having the first magnet holding portion 31 and the number C of the electromagnetic steel plate (first electromagnetic steel plate 201) having the second magnet holding portion 32 are Since they are the same, the electromagnetic steel sheets constituting the rotor core 20 can be of two types, the first electromagnetic steel sheet 201 and the second electrical steel sheet 202. As a result, the number of types of dies for pressing the electromagnetic steel sheet can be reduced, and the manufacturing cost can be reduced.

Further, a first electrical steel sheet 201 having magnet holding portions 31 and 32 is arranged at at least one end in the rotation axis direction of the rotor core 20. Therefore, when the permanent magnet 40 is inserted into the magnet insertion hole 22, the magnet holding portions 31 and 32 function as guides for the permanent magnet 40, facilitating the insertion work of the permanent magnet 40.

The permanent magnet 40 is a rare earth magnet containing neodymium (Nd), iron (Fe) and boron (B) as main components, and the residual magnetic flux density at 20 ° C. is within the range of 1.27T to 1.42T. Yes, the coercive force at 20 ° C. is in the range of 1671 kA / m to 1922 kA / m. Therefore, dysprosium can be eliminated, and a decrease in residual magnetic flux density due to the addition of dysprosium can be avoided. That is, the current value required to obtain the same torque can be reduced, copper loss can be reduced, and the efficiency of the electric motor can be improved.

Further, the magnet insertion hole 22 has a V-shape in which the central portion in the circumferential direction protrudes inward in the radial direction, and two permanent magnets 40 are arranged. Therefore, two permanent magnets 40 can be arranged in a V shape on one magnetic pole, thereby reducing in-plane eddy current loss in the permanent magnets 40, improving the efficiency of the electric motor, and reducing energy consumption. It can be reduced.

Further, the rotary compressor 300 using the electric motor 100 is used as, for example, the compressor 401 of the refrigeration and air conditioner 400. In this case, the electric motor 100 is used in a high temperature atmosphere and is susceptible to load fluctuations. Since the electric motor 100 of the first embodiment has a configuration that suppresses the demagnetization of the permanent magnet 40 as described above, it is suitable for use in the compressor 401 of such a refrigerating air conditioner 400.

Embodiment 2.
Next, Embodiment 2 of the present invention will be described. The second embodiment aims to effectively suppress demagnetization caused by leakage flux between adjacent permanent magnets 40 in the magnet insertion hole 22.

In the rotor core 20 of the second embodiment, in addition to the first electrical steel sheet 201 (FIGS. 2 to 3) and the second electrical steel sheet 202 (FIGS. 4 to 5) described in the first embodiment, the rotor core 20 has a third aspect. The electromagnetic steel plate 203 is used. FIG. 10 is a cross-sectional view of the rotor 2 showing the third electromagnetic steel plate 203 of the second embodiment in a plan view. FIG. 11 is a cross-sectional view of the rotor core 20 showing the third electromagnetic steel plate 203 in a plan view.

Like the first electromagnetic steel sheet 201, the third electrical steel sheet 203 has a plurality of (here, six) magnet insertion holes 22. The magnet insertion hole 22 has a V-shape in which the central portion in the circumferential direction protrudes inward in the radial direction, and two permanent magnets 40 are arranged in one magnet insertion hole 22.

However, as shown in FIG. 11, the third electromagnetic steel sheet 203 has the second magnet holding portion 32 at the circumferential end of the magnet insertion hole 22, but the first magnet holding portion 31 at the circumferential central portion. Does not have. In other words, the first magnet holding portion 31 is not provided between the permanent magnets 40 adjacent to each other in the magnet insertion hole 22.

Leakage magnetic flux is likely to occur between the permanent magnets 40 adjacent to each other in the magnet insertion hole 22. Therefore, the demagnetization of the permanent magnet 40 is more likely to proceed at the central portion in the circumferential direction than at the circumferential end portion of the magnet insertion hole 22. Therefore, in the second embodiment, the third electromagnetic steel having the second magnet holding portion 32 at the circumferential end of the magnet insertion hole 22 and not having the first magnet holding portion 31 at the central portion in the circumferential direction. Steel plate 203 is used.

FIG. 12 is a diagram showing a laminated structure of the rotor core 20 according to the second embodiment. The rotor core 20 has N1 first electrical steel sheet 201, N2 second electrical steel sheet 202, and N3 third electrical steel sheet 203 and N4 in order from the top in FIG. 12 in the direction of its rotation axis. The second electromagnetic steel sheet 202 and N5 first electromagnetic steel sheets 201 are laminated. That is, the first electromagnetic steel plate 201 is arranged at both ends in the direction of the rotation axis (lamination direction) of the rotor core 20, and the third electromagnetic steel plate 203 is arranged at the central portion.

The total number A of the electromagnetic steel sheets constituting the rotor core 20 is N1 + N2 + N3 + N4 + N5. On the other hand, among the electromagnetic steel sheets constituting the rotor core 20, the number B of the electromagnetic steel sheets (first electromagnetic steel sheet 201) having the first magnet holding portion 31 between the permanent magnets 40 adjacent to each other in the magnet insertion hole 22 is It is N1 + N5. Further, among the electromagnetic steel sheets constituting the rotor core 20, the number of electromagnetic steel sheets (first electromagnetic steel sheet 201 and third electromagnetic steel sheet 203) having a second magnet holding portion 32 at the circumferential end of the magnet insertion hole 22. C is N1 + N3 + N5.

That is, the total number A of the electromagnetic steel sheets constituting the rotor core 20 and the number B of the electromagnetic steel sheets (first electromagnetic steel sheet 201) having the first magnet holding portion 31 between the permanent magnets 40 adjacent to each other in the magnet insertion hole 22. The number C of the electrical steel sheets (the first electrical steel sheet 201 and the third electrical steel sheet 203) having the second magnet holding portion 32 at the circumferential end of the magnet insertion hole 22 is A> C> B. Satisfy the relationship.

In the second embodiment, the first magnetic steel sheet 201 of the rotor core 20 has magnet holding portions 31 and 32 at the central portion in the circumferential direction and the end portion in the circumferential direction of the magnet insertion hole 22, respectively, and the third electromagnetic steel plate 203. However, since the second magnet holding portion 32 is provided at the circumferential end of the magnet insertion hole 22, the permanent magnet 40 can be positioned so as not to move in the magnet insertion hole 22.

Further, since the second electromagnetic steel plate 202 of the rotor core 20 does not have the magnet holding portions 31 and 32 in the magnet insertion holes 22, the magnet holding even when the current flowing through the coil 15 of the stator 1 becomes large. It is possible to suppress demagnetization of the permanent magnet 40 due to the magnetic flux flowing from the portions 31 and 32 to the permanent magnet 40.

Further, the third electromagnetic steel plate 203 of the rotor core 20 has the second magnet holding portion 32 at the circumferential end of the magnet insertion hole 22, and does not have the first magnet holding portion 31 at the circumferential center. Therefore, demagnetization due to leakage flux between adjacent permanent magnets 40 in the magnet insertion hole 22 can be effectively suppressed.

Further, as described in the first embodiment, by providing the first electromagnetic steel plate 201 at at least one end in the rotation axis direction of the rotor core 20, the magnet holding portion is formed when the permanent magnet 40 is inserted into the magnet insertion hole 22. 31 and 32 function as guides for the permanent magnet 40, facilitating the work of inserting the permanent magnet 40.

Further, by arranging the first electromagnetic steel sheet 201 at both ends of the rotor core 20 in the rotation axis direction and arranging the third electrical steel sheet 203 at the center, the inclination of the permanent magnet 40 can be suppressed.

The electric motor of the second embodiment has the same configuration as the electric motor 100 described in the first embodiment except for the configuration of the rotor core 20. Further, the electric motor of the second embodiment can be used for the rotary compressor 300 (FIG. 8) and the refrigerating air conditioner 400 (FIG. 9) described in the first embodiment.

Next, the results of measuring the change in the demagnetization rate with respect to the current will be described for each of the electric motor of the second embodiment and the electric motor of the comparative example.

As described above, the electric motor of the second embodiment comprises the rotor core 20 by laminating the first electromagnetic steel sheet 201, the second electrical steel sheet 202, and the third electrical steel sheet 203 as shown in FIG. is there. The dimensions of the rotor core 20 in the direction of the rotation axis were 50 mm, the laminated thickness of the first electromagnetic steel sheet 201 at the top and bottom was 5 mm, and the laminated thickness of the third electrical steel sheet 203 was 5 mm. The electric motor of the comparative example is the same as the electric motor of the second embodiment except that the rotor core 20 is composed of only one type of the first electromagnetic steel plate 201.

FIG. 13 is a graph showing changes in the demagnetization rate of the electric motor of the second embodiment and the electric motor of the comparative example. The horizontal axis is the current (A) passed through the coil 15 of the stator 1 (FIG. 1), and the vertical axis is the demagnetization rate (%). Here, the demagnetization rate of the permanent magnet 40 was measured by changing the current flowing through the coil 15 of the stator 1 from 0A to 15A.

Generally, in a permanent magnet embedded motor, the pass / fail criterion for the demagnetization rate of the permanent magnet is -3%. From the graph of FIG. 13, it can be seen that in the electric motor of the second embodiment, the current at which the demagnetization rate reaches -3% (3% demagnetization current) is increased by about 10% as compared with the electric motor of the comparative example. .. That is, it can be seen that the electric motor of the second embodiment has a wider range of usable current than the electric motor of the comparative example.

Further, when the electric motor of the second embodiment is driven by the same current as the electric motor of the comparative example, a permanent magnet having a lower coercive force can be used. That is, the amount of dysprosium or the like added to improve the coercive force of the permanent magnet can be reduced or eliminated. Therefore, the efficiency of the electric motor can be improved by reducing the manufacturing cost and avoiding the decrease in the residual magnetic flux density due to the addition of dysprosium.

As described above, in the second embodiment of the present invention, the first magnet holding portion 31 is provided between the total number A of the electromagnetic steel sheets constituting the rotor core 20 and the adjacent permanent magnets 40 in the magnet insertion hole 22. An electromagnetic steel sheet (first electromagnetic steel sheet 201 and third electromagnetic steel sheet 203) having a number B of electromagnetic steel sheets (first electromagnetic steel sheet 201) and a second magnet holding portion 32 at the circumferential end of the magnet insertion hole 22. ) Satisfyes the relationship of A> C> B. Therefore, in addition to the effect described in the first embodiment, demagnetization due to leakage flux between adjacent permanent magnets 40 in the magnet insertion hole 22 can be effectively suppressed.

In the first and second embodiments described above, the case where the rotor core 20 has the first electrical steel sheet 201 and the second electrical steel sheet 202 (in the second embodiment, the third electrical steel sheet 203) is described. However, it may have yet another electrical steel sheet.

FIG. 14 is a cross-sectional view of the rotor 2 showing the fourth electromagnetic steel plate 204 of the modified examples of the first and second embodiments in a plan view. FIG. 15 is a cross-sectional view of the rotor core 20 showing the fourth electromagnetic steel plate 204 in a plan view.

Like the first electromagnetic steel sheet 201, the fourth electrical steel sheet 204 has a plurality of (here, six) magnet insertion holes 22. The magnet insertion hole 22 has a V-shape in which the central portion in the circumferential direction protrudes inward in the radial direction, and two permanent magnets 40 are arranged in one magnet insertion hole 22. However, the fourth electromagnetic steel plate 204 has the first magnet holding portion 31 at the central portion in the circumferential direction of the magnet insertion hole 22, but does not have the second magnet holding portion 32 at the peripheral end portion.

Since the fourth electromagnetic steel plate 204 has the first magnet holding portion 31 at the central portion in the circumferential direction of the magnet insertion hole 22, the effect of suppressing the demagnetization of the permanent magnet 40 is the third electromagnetic steel plate 203 ( Although it is smaller than FIGS. 10 to 11), it has a function of positioning the permanent magnet 40 at the central portion in the circumferential direction of the magnet insertion hole 22. Therefore, for example, if the fourth electromagnetic steel plate 204 is used as a part of the rotor core 20 in the second embodiment in the rotation axis direction, the first magnet holding portion 31 serves as a guide for the permanent magnet 40, so that the magnet insertion hole 22 The permanent magnet 40 can be easily inserted into the magnet.

FIG. 16 is a cross-sectional view of the rotor 2 showing the fifth electromagnetic steel plate 205 in another modified example in a plan view. FIG. 17 is a cross-sectional view of the rotor core 20 showing the fifth electromagnetic steel plate 205 in a plan view.

Like the first electromagnetic steel sheet 201, the fifth electrical steel sheet 205 has a plurality of (six here) magnet insertion holes 22. The magnet insertion hole 22 has a V-shape in which the central portion in the circumferential direction protrudes inward in the radial direction, and two permanent magnets 40 are arranged in one magnet insertion hole 22.

However, the fifth electromagnetic steel plate 205 has a region in which the first magnet holding portion 31 is provided in the central portion of the magnet insertion hole 22 in the circumferential direction and the second magnet holding portion 32 is not provided in the peripheral end portion, and a magnet. A second magnet holding portion 32 is provided at the circumferential end of the insertion hole 22, and a region in which the first magnet holding portion 31 is not provided is provided at the central portion in the circumferential direction. Here, in the circumferential direction of the rotor core 20, the first magnet holding portion 31 is provided at the central portion in the circumferential direction of the magnet insertion hole 22, and the second magnet holding portion 32 is provided at the circumferential end of the magnet insertion hole 22. The magnets provided with the above are arranged alternately. The electromagnetic steel sheet 20 5 of the fifth, may be added to the rotor core 20 of the first or second embodiment.

Embodiment 3.
Next, Embodiment 3 of the present invention will be described. The third embodiment aims at positioning the permanent magnet 40 in the magnet insertion hole 25 and suppressing demagnetization of the permanent magnet 40 in the rotor 2A having the permanent magnet 40 in the linear magnet insertion hole 25. And.

The rotor core 20A of the rotor 2A of the third embodiment includes a first electrical steel sheet 206 (FIGS. 18 to 19) and a second electrical steel sheet 207 (FIGS. 20 to 21). FIG. 18 is a cross-sectional view of the rotor 2A showing the first electromagnetic steel plate 206 in a plan view. FIG. 19 is a cross-sectional view of the rotor core 20A showing the first electromagnetic steel plate 206 in a plan view.

The first electrical steel sheet 206 has a plurality of (here, six) magnet insertion holes 25. Unlike the V-shaped magnet insertion hole 22 of the first embodiment, the magnet insertion hole 25 extends linearly along the outer circumference of the rotor core 20A. One magnet insertion hole 25 corresponds to one magnetic pole. The extending direction of the magnet insertion hole 25 is a direction orthogonal to the radial direction of the rotor core 20A at the center of the magnetic pole. Two permanent magnets 40 are arranged in one magnet insertion hole 25.

The first magnetic steel sheet 206 has a first magnet holding portion 31 at the central portion in the circumferential direction of the magnet insertion hole 25, and a second magnet holding portion 32 at the peripheral end portion. Further, flux barriers 24 are formed on both sides of the magnet insertion hole 25 in the circumferential direction. The configurations of the magnet holding portions 31 and 32 and the flux barrier 24 are as described in the first embodiment.

FIG. 20 is a cross-sectional view of the rotor 2A showing the second electromagnetic steel plate 207 in a plan view. FIG. 21 is a cross-sectional view of the rotor core 20A showing the second electromagnetic steel plate 207 in a plan view.

Like the first electromagnetic steel sheet 206, the second electrical steel sheet 207 has a plurality of (here, six) magnet insertion holes 25. The magnet insertion hole 25 extends linearly, and two permanent magnets 40 are arranged in one magnet insertion hole 25. However, the magnet insertion holes 25 of the second electrical steel sheet 207 are not provided with the magnet holding portions 31 and 32.

The first electromagnetic steel sheet 206 and the second electrical steel sheet 207 can be laminated in the same manner as the first electrical steel sheet 201 and the second electrical steel sheet 202 described in the first embodiment. For example, as described with reference to FIG. 6, the first electrical steel sheet 206 is laminated on both ends and the central portion (third stage) of the rotor core 20A in the rotation axis direction, and the second electrical steel sheet 207 is stacked in two stages. It can be laminated on the eyes and the fourth stage.

The laminated structure of the first electromagnetic steel sheet 206 and the second electrical steel sheet 207 is not limited to the laminated structure described with reference to FIG. 6, and may be, for example, the laminated structure described with reference to FIG. 7. .. Further, as described in the second embodiment, the electromagnetic steel having the second magnet holding portion 32 at the circumferential end portion of the magnet insertion hole 25 and not having the first magnet holding portion 31 at the circumferential central portion. Further steel plates may be added.

Since the first electromagnetic steel plate 206 of the rotor core 20A has the magnet holding portions 31 and 32 in the magnet insertion hole 25, the permanent magnet 40 can be positioned in the magnet insertion hole 25. Further, since the second electromagnetic steel plate 207 of the rotor core 20A does not have the magnet holding portions 31 and 32 in the magnet insertion holes 25, the permanent magnet 40 is caused by the magnetic flux flowing from the magnet holding portions 31 and 32 to the permanent magnet 40. Demagnetization can be suppressed.

The electric motor of the third embodiment has the same configuration as the electric motor 100 described in the first embodiment except for the configuration of the rotor core 20A. Further, the electric motor of the third embodiment can be used for the rotary compressor 300 (FIG. 8) and the refrigerating air conditioner 400 (FIG. 9) described in the first embodiment.

As described above, according to the third embodiment of the present invention, the permanent magnet 40 is positioned in the magnet insertion hole 25 and the permanent magnet is formed even in the configuration in which the rotor core 20A is provided with the linear magnet insertion hole 25. Demagnetization of 40 can be suppressed.

Embodiment 4.
Next, Embodiment 4 of the present invention will be described. In the fourth embodiment, in the rotor 2B in which the three permanent magnets 40 are arranged in one magnet insertion hole 26, the permanent magnet 40 is positioned in the magnet insertion hole 26 and the demagnetization of the permanent magnet 40 is suppressed. With the goal.

The rotor core 20B of the rotor 2B of the fourth embodiment includes a first electrical steel sheet 208 (FIGS. 22 to 23) and a second electrical steel sheet 209 (FIGS. 24 to 25). FIG. 22 is a cross-sectional view of the rotor 2 showing the first electromagnetic steel plate 208 in a plan view. FIG. 23 is a cross-sectional view of the rotor core 20B showing the first electromagnetic steel plate 208 in a plan view.

The first electrical steel sheet 208 has a plurality of (here, six) magnet insertion holes 26. One magnet insertion hole 26 corresponds to one magnetic pole. Three permanent magnets 40 are arranged in each of the magnet insertion holes 26. That is, three permanent magnets 40 are arranged for one magnetic pole. Here, since the rotor 2B has 6 poles as described above, a total of 18 permanent magnets 40 are arranged.

As shown in FIG. 23, the magnet insertion hole 26 has a first portion 26a, a second portion 26b, and a third portion 26c along the outer circumference of the rotor core 20B. The permanent magnet 40 is inserted into each of these three portions 26a, 26b, 26c.

Of the first portion 26a, the second portion 26b, and the third portion 26c of the magnet insertion hole 26, the second portion 26b located at the central portion in the circumferential direction is located at the innermost radial direction and is peripheral. It extends linearly in the direction. The first portion 26a and the third portion 26c extend radially outward from both ends of the second portion 26b, respectively. The distance between the first portion 26a and the third portion 26c increases as it approaches the outer circumference of the rotor core 20B. The shape of the magnet insertion hole 26 is also called a bathtub shape.

The first magnetic steel sheet 208 has a first magnet holding portion 31 at the central portion in the circumferential direction of the magnet insertion hole 26, and a second magnet holding portion 32 at the peripheral end portion. Further, flux barriers 24 are formed on both sides of the magnet insertion hole 26 in the circumferential direction. The configurations of the magnet holding portions 31 and 32 and the flux barrier 24 are as described in the first embodiment.

FIG. 24 is a cross-sectional view of the rotor 2B showing the second electromagnetic steel plate 209 of the fourth embodiment in a plan view. FIG. 25 is a cross-sectional view of the rotor core 20B showing the second electromagnetic steel plate 209 in a plan view.

Like the first electromagnetic steel sheet 208, the second electrical steel sheet 209 has a plurality of (here, six) magnet insertion holes 26. The magnet insertion hole 26 has a bathtub shape, and three permanent magnets 40 are arranged in one magnet insertion hole 26. However, as shown in FIG. 25, the magnet insertion holes 26 of the second electrical steel sheet 209 are not provided with the magnet holding portions 31 and 32.

The first electrical steel sheet 208 and the second electrical steel sheet 209 can be laminated in the same manner as the first electrical steel sheet 201 and the second electrical steel sheet 202 described in the first embodiment. For example, as described with reference to FIG. 6, the first electrical steel sheet 208 is laminated on both ends and the central portion (third stage) of the rotor core 20B in the rotation axis direction, and the second electrical steel sheet 209 is laminated in two stages. It can be laminated on the eyes and the fourth stage.

The laminated structure of the first electromagnetic steel sheet 208 and the second electrical steel sheet 209 is not limited to the laminated structure described with reference to FIG. 6, and may be, for example, the laminated structure described with reference to FIG. 7. .. Further, as described in the second embodiment, the second magnet holding portion 32 is provided at the circumferential end portion of the magnet insertion hole 26, and the first magnet holding portion 31 is provided at the circumferential central portion of the magnet insertion hole 26. An electromagnetic steel sheet that does not have the above may be added.

Since the first electromagnetic steel plate 208 of the rotor core 20B has the magnet holding portions 31 and 32 in the magnet insertion hole 26, the permanent magnet 40 can be positioned in the magnet insertion hole 26. Further, since the second electromagnetic steel plate 209 of the rotor core 20B does not have the magnet holding portions 31 and 32 in the magnet insertion holes 26, demagnetization of the permanent magnet 40 due to the magnetic flux passing through the magnet holding portions 31 and 32 is suppressed. can do.

The electric motor of the fourth embodiment has the same configuration as the electric motor 100 described in the first embodiment except for the configuration of the rotor core 20B. Further, the electric motor of the fourth embodiment can be used for the rotary compressor 300 (FIG. 8) and the refrigerating air conditioner 400 (FIG. 9) described in the first embodiment.

As described above, according to the fourth embodiment of the present invention, even in a configuration in which the rotor core 20B is provided with a bathtub-shaped magnet insertion hole 26 and three permanent magnets 40 are arranged in each magnet insertion hole 26, it is permanent. The magnet 40 can be positioned in the magnet insertion hole 26, and demagnetization of the permanent magnet 40 can be suppressed.

Embodiment 5.
Next, a fifth embodiment of the present invention will be described. An object of the fifth embodiment is to further enhance the effect of suppressing demagnetization of the permanent magnet 40 by providing a gap 28 inside the magnet insertion hole 22 of the rotor core 20 in the radial direction.

The rotor core 20 of the fifth embodiment is formed by adding a gap 28 inside the magnet insertion hole 22 in the radial direction to the first electrical steel sheet 201 and the second electrical steel sheet 202 described in the first embodiment. FIG. 26 is a cross-sectional view of the rotor core 20 showing the first electromagnetic steel plate 210 of the fifth embodiment in a plan view. FIG. 27 is a cross-sectional view of the rotor core 20 showing the second electromagnetic steel plate 211 in a plan view.

The first electrical steel sheet 210 of the fifth embodiment is configured in the same manner as the first electrical steel sheet 201 (FIGS. 2 to 3) described above, but the first magnet in the central portion in the circumferential direction of the magnet insertion hole 22. A gap 28 is provided inside the holding portion 31 in the radial direction.

Further, the second electrical steel sheet 211 of the fifth embodiment is configured in the same manner as the second electrical steel sheet 202 (FIGS. 4 to 5) described above, but in the radial direction of the central portion in the circumferential direction of the magnet insertion hole 22. It has a void 28 inside.

The gap 28 is provided so as to penetrate the rotor core 20 in the direction of the rotation axis. The gap 28 increases the magnetic resistance of the first magnet holding portion 31 to prevent the magnetic flux from the coil 15 of the stator 1 from flowing through the first magnet holding portion 31.

By arranging the voids 28 in this way, demagnetization of the permanent magnet 40 due to the magnetic flux flowing from the first magnet holding portion 31 to the permanent magnet 40 can be suppressed. Further, the void 28 also has a function of passing the refrigerant of the rotary compressor 300 (FIG. 8) in the direction of the rotation axis to cool the rotor core 20 and the permanent magnet 40, for example.

It is desirable that the gap 28 is as close to the magnet insertion hole 22 as possible. This is because the closer the gap 28 is to the magnet insertion hole 22, the higher the magnetic resistance of the first magnet holding portion 31. Here, the distance from the gap 28 to the magnet insertion hole 22 is made shorter than the distance from the gap 28 to the shaft hole 21. The minimum value of the distance from the gap 28 to the magnet insertion hole 22 is the same as the thickness of the electromagnetic steel plate constituting the rotor core 20 (for example, 0.35 mm), and the maximum value is 3 mm.

The laminated structure of the first electrical steel sheet 210 and the second electrical steel sheet 211 is as described with reference to FIG. 6 or FIG. 7 in the first embodiment. Further, the third electromagnetic steel sheet 203 described in the second embodiment with voids 28 added may be used.

The electric motor of the fifth embodiment has the same configuration as the electric motor 100 described in the first embodiment except for the configuration of the rotor core 20. Further, the electric motor of the fifth embodiment can be used for the rotary compressor 300 (FIG. 8) and the refrigerating air conditioner 400 (FIG. 9) described in the first embodiment.

As described above, according to the fifth embodiment of the present invention, a gap 28 is provided inside the magnet holding portion 31 in the circumferential central portion of the magnet insertion hole 22 in the radial direction, and the gap 28 to the magnet insertion hole 22 is provided. By making the distance shorter than the distance from the gap 28 to the shaft hole 21, in addition to the effect described in the first embodiment, the magnetic resistance of the first magnet holding portion 31 is increased, whereby the permanent magnet 40 The effect of suppressing demagnetization can be further enhanced.

It is also possible to add the void 28 described in the fifth embodiment to the rotor core 20 described in the third and fourth embodiments described above.

Although the preferred embodiments of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments, and various improvements or modifications are made without departing from the gist of the present invention. be able to.

For example, in each of the above embodiments, the rotor 2 (2A, 2B) has six magnet insertion holes 22 (25, 26), but the number of magnet insertion holes is the magnetic pole of the rotor 2 (2A, 2B). It can be changed as appropriate according to the number. Further, in each of the above embodiments, the number of permanent magnets 40 arranged in one magnet insertion hole 22 (25, 26) is two or three, but even if four or more permanent magnets 40 are arranged. Good.

Further, the compressor using the electric motor 100 of each of the above embodiments is not limited to the rotary compressor 300 described with reference to FIG. 8, and may be another type of compressor. Further, the refrigerating and air-conditioning apparatus using the electric motor 100 is not limited to the refrigerating and air-conditioning apparatus 400 described with reference to FIG.

1 stator, 10 stator core, 12 teeth, 15 coil, 2 rotor, 20 rotor core, 21 shaft hole (center hole), 22, 25, 26 magnet insertion hole, 24 flux barrier, 28 void, 31, 32, 33 magnet holder , 40 Permanent magnets, 201, 206, 208, 210 first electrical steel sheets, 202, 207, 209, 211 second electrical steel sheets, 203 third electrical steel sheets, 204 fourth electrical steel sheets, 205 fifth electrical steel Steel plate, 300 rotary compressor (compressor), 301 frame, 310 compression mechanism, 315 shaft, 400 refrigeration and air conditioner, 410 compressor.

Claims (12)

A stator and a rotor arranged inside the stator are provided.
The rotor
A rotor core with a magnet insertion hole and
It has two adjacent permanent magnets arranged in the magnet insertion holes of the rotor core.
The magnet insertion hole is formed continuously in a V shape in which the central portion in the circumferential direction of the rotor core projects inward in the radial direction of the rotor core.
The rotor core has a first magnet holding portion arranged between two adjacent permanent magnets in the magnet insertion hole and a second magnet holding portion arranged at the end of the magnet insertion hole in the circumferential direction of the rotor core. Has a magnet holding part and
The first magnet holding portion and the second magnet holding portion are protrusions formed in the magnet insertion hole, and a gap is formed in the magnet insertion hole on the outer side of the protrusion in the radial direction. ,
The rotor core is formed by laminating a plurality of electromagnetic steel plates in the axial direction.
Let A be the number of the plurality of electromagnetic steel plates of the rotor core.
When the number of electromagnetic steel sheets having the first magnet holding portion is B and the number of electrical steel sheets having the second magnet holding portion is C among the plurality of electromagnetic steel plates of the rotor core.
A> B and A> C
The electric motor that establishes the relationship. Moreover, the relationship of B = C is met, the electric motor according to claim 1. The plurality of electromagnetic steel plates of the rotor core are
A first electromagnetic steel sheet having the first magnet holding portion and the second magnet holding portion, and
The electric motor according to claim 2 , further comprising a second magnetic steel sheet having neither the first magnet holding portion nor the second magnet holding portion. Furthermore, C> relationship B is satisfied, the electric motor according to claim 1. The plurality of electromagnetic steel plates of the rotor core are
A first electromagnetic steel sheet having the first magnet holding portion and the second magnet holding portion, and
A second electrical steel sheet having neither the first magnet holding portion nor the second magnet holding portion,
A third electromagnetic steel sheet having the second magnet holding portion without having the first magnet holding portion, and
4. The electric motor according to claim 4 . The plurality of electromagnetic steel plates of the rotor core are
A first electromagnetic steel sheet having the first magnet holding portion and the second magnet holding portion, and
A second electrical steel sheet having neither the first magnet holding portion nor the second magnet holding portion,
A third electromagnetic steel sheet having the second magnet holding portion without having the first magnet holding portion, and
The electric motor according to claim 1 , further comprising a fourth electrical steel sheet having the first magnet holding portion without having the second magnet holding portion. Among the plurality of electromagnetic steel sheets of the rotor core, the electrical steel sheets arranged at one end in the stacking direction have at least one of the first magnet holding portion and the second magnet holding portion, claims 1 to 6. The electric motor according to any one of the items up to. The plurality of permanent magnets are rare earth magnets mainly composed of neodymium (Nd), iron (Fe) and boron (B), and have a residual magnetic flux density of 1.27T to 1.42T at 20 ° C. The electric motor according to any one of claims 1 to 7 , which is within the range and has a coercive force at 20 ° C. in the range of 1671 kA / m to 1922 kA / m. The rotor core has a gap portion inside the first magnet holding portion in the radial direction.
The rotor core further has a central hole in the radial center.
Distance from the gap portion to the magnet insertion holes is shorter than the distance from the gap to the center hole, the electric motor according to any one of claims 1 to 7. A rotor core with a magnet insertion hole and
It has two adjacent permanent magnets arranged in the magnet insertion holes of the rotor core.
The magnet insertion hole is formed continuously in a V shape in which the central portion of the rotor core in the circumferential direction protrudes inward in the radial direction of the rotor core.
The rotor core has a first magnet holding portion arranged between two adjacent permanent magnets in the magnet insertion hole and a second magnet holding portion arranged at the end of the magnet insertion hole in the circumferential direction of the rotor core. Has a magnet holding part and
The first magnet holding portion and the second magnet holding portion are protrusions formed in the magnet insertion hole, and a gap is formed on the outer peripheral side of the protrusion in the magnet insertion hole.
The rotor core is formed by laminating a plurality of electromagnetic steel plates in the axial direction.
Let A be the number of the plurality of electromagnetic steel plates of the rotor core.
When the number of electromagnetic steel sheets having the first magnet holding portion is B and the number of electrical steel sheets having the second magnet holding portion is C among the plurality of electromagnetic steel plates of the rotor core.
A> B and A> C
The rotor that establishes the relationship. Compressor comprising a motor; and a compression mechanism driven by said electric motor to any one of claims 1 to 9. A refrigeration and air conditioner equipped with a compressor, a condenser, a decompression device and an evaporator.
The compressor is a freezing air conditioner including the electric motor according to any one of claims 1 to 9 and a compression mechanism driven by the electric motor.

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