WO2016006103A1

WO2016006103A1 - Electric motor with embedded permanent magnet, compressor, and refrigerating and air conditioning device

Info

Publication number: WO2016006103A1
Application number: PCT/JP2014/068586
Authority: WO
Inventors: 敦史石川; 馬場　和彦; 昌弘仁吾
Original assignee: 三菱電機株式会社
Priority date: 2014-07-11
Filing date: 2014-07-11
Publication date: 2016-01-14

Abstract

In this electric motor with an embedded permanent magnet, the hole interior line (53) of a magnet insertion hole (21) is formed from a first circular arc having a radius (r1), a hole exterior line (55) is formed from a second circular arc having a radius (r2), the first circular arc and the second circular arc protrude toward the center of rotation of a rotor, the center (O1) of the first circular arc and the center (O2) of the second circular arc are positioned on a magnetic pole center line (ML), the distance (x1) in the magnetic pole center line (ML) direction between the center (O1) of the first circular arc and a rotation center line (CL) is larger than the distance (x2) in the magnetic pole center line (ML) direction between the center (O2) of the second circular arc and the rotation center line (CL), and the distance (x1) - the distance (x2) > the radius (r1) - the radius (r2).

Description

Permanent magnet embedded electric motor, compressor and refrigeration air conditioner

The present invention relates to a permanent magnet embedded electric motor, a compressor, and a refrigeration air conditioner.

In recent years, a highly efficient electric motor has been required due to an increase in energy saving awareness. In existing permanent magnet embedded motors, the magnet insertion holes and permanent magnets have a reverse arc shape, thereby increasing the surface area of the magnets to improve the magnetic force and increasing the magnet torque caused by the magnetic flux. On the other hand, in such a permanent magnet embedded motor, the permanent magnet may move in the magnet insertion hole while the rotor is rotating. A fixing protrusion (stopper) is provided. However, by providing the projection, the magnetic flux due to the demagnetizing field flows into the magnet end portion through the projection during operation, and the partial demagnetization of the magnet is deteriorated. That is, such protrusions cause demagnetization of the end portions of the permanent magnet, and hinder improvement in the efficiency of the electric motor.

Apart from the above, many permanent magnet embedded motors have been proposed that achieve high efficiency by using rare earth magnets with high residual magnetic flux density and coercive force for the rotor. In order to increase the residual magnetic flux density and the coercive force, the rare earth magnet contains rare earth elements (rare earth) such as neodymium (Nd), dysprosium (Dy), and terbium (Tb).

However, currently, rare earth elements have problems of price increase and supply instability, and in the future, electric motors using rare earth magnets with reduced contents of Dy and Tb, and electric motors not using rare earth magnets will be used. Development is expected to proceed.

As an electric motor not using a rare earth magnet, for example, there is a policy of using an inexpensive ferrite magnet mainly composed of iron oxide. However, compared to rare earth magnets, ferrite magnets have a residual magnetic flux density of about 1/3 and a coercive force of about 1/3. Therefore, in an electric motor using a ferrite magnet, deterioration of efficiency and demagnetization resistance are the main issues.

Further, as a technique for improving the efficiency of a permanent magnet embedded electric motor using a ferrite magnet, there is a technique disclosed in Patent Document 1, for example. In this permanent magnet embedded type electric motor, three thin arc-shaped magnets are provided per pole to secure the q-axis magnetic flux and improve the reluctance torque.

JP 2011-083066 A

However, as described above, when three thin magnets are used per pole, the thickness of one magnet is thin, so that it is easily affected by the demagnetizing field generated from the stator winding during operation. There is a risk of demagnetization of the magnet. Therefore, in the permanent magnet embedded type electric motor, it is necessary to mitigate the influence of the demagnetizing field received by the magnet.

In order to solve the above-described problems, an object of the present invention is to provide a permanent magnet embedded type electric motor that can ensure high demagnetization resistance without depending on a rare earth magnet.

In order to achieve the above-described object, an embedded permanent magnet electric motor of the present invention includes a stator and a rotor that is rotatably provided to face the stator, and the rotor includes a plurality of permanent magnets and a rotor core. The rotor core has a plurality of magnet insertion holes, the permanent magnet is inserted into the magnet insertion hole, and the outline of the magnet insertion hole is the rotation center of the rotor When viewed in a plane with the line CL as a perpendicular, the hole includes an inner hole line and an outer hole line, the permanent magnet includes a magnet inner surface and a magnet outer surface, and the magnet inner surface is the hole. Contacting the inner line, the magnet outer surface is in contact with the hole outer line, the hole inner line is constituted by a first arc having a radius r1, and the hole outer line is constituted by a second arc having a radius r2. Wait The first arc and the second arc protrude toward the rotation center of the rotor, and the center O1 of the first arc and the center O2 of the second arc are located on the magnetic pole center line ML. The distance x1 between the center O1 of the first arc and the rotation center line CL in the magnetic pole center line ML direction is the distance between the center O2 of the second arc and the rotation center line CL. The distance x2 in the magnetic pole center line ML direction is larger than the distance x2, and the distance x1−the distance x2 is larger than the radius r1−the radius r2.
Furthermore, a compressor according to the present invention for achieving the same object includes an electric motor and a compression element in a sealed container, and the electric motor is the above-described permanent magnet embedded electric motor according to the present invention.
Furthermore, the refrigerating and air-conditioning apparatus according to the present invention for achieving the same object includes the above-described compressor according to the present invention as a component of the refrigeration circuit.

According to the present invention, high demagnetization resistance can be ensured without depending on the rare earth magnet.

It is a figure which shows the cross section orthogonal to the rotation centerline of the permanent magnet embedded electric motor of Embodiment 1 of this invention. It is a figure which shows the rotor single-piece | unit in FIG. It is a figure which shows the curve aspect of a magnet insertion hole. It is a figure which shows the state which inserted the magnet in the magnet insertion hole in FIG. It is a figure of the same aspect as FIG. 4 regarding Embodiment 2 of this invention. It is a longitudinal cross-sectional view of the rotary compressor of Embodiment 3 of this invention carrying a permanent magnet embedded type electric motor.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, the same reference numerals indicate the same or corresponding parts. 3 to 5 are views showing a part of the rotor in the cross section shown in FIG. 1, the hatching is omitted in order to give priority to the clarity of the drawing.

Embodiment 1 FIG.
FIG. 1 is a view showing a cross section orthogonal to the rotation center line of the permanent magnet embedded electric motor according to Embodiment 1 of the present invention. FIG. 2 is a diagram showing a single rotor in FIG.

The embedded permanent magnet electric motor 1 includes a stator 3 and a rotor 5 that is rotatably provided facing the stator 3. The stator 3 has a plurality of tooth portions 7. Each of the plurality of tooth portions 7 is adjacent to another tooth portion 7 via a corresponding slot portion 9. The plurality of tooth portions 7 and the plurality of slot portions 9 are arranged so as to be alternately arranged at equal intervals in the circumferential direction.

The stator winding 3a is wound around each of the plurality of tooth portions 7 by a so-called distributed winding method. The distributed winding method is a winding method in which windings are distributed and distributed over a plurality of tooth portions 7 of the stator 3. This distributed winding method is superior to the concentrated winding method in that it uses reluctance torque.

The rotor 5 has a rotor core 11 and a shaft 13. The shaft 13 is connected to the axial center portion of the rotor core 11 by shrink fitting, press fitting, or the like, and transmits rotational energy to the rotor core 11. An air gap 15 is secured between the outer peripheral surface of the rotor 5 and the inner peripheral surface of the stator 3.

In such a configuration, the rotor 5 is held inside the stator 3 via the air gap 15 so as to be rotatable about the rotation center line CL (rotor center of the rotor, shaft axis). Specifically, a current of a frequency synchronized with the command rotational speed is supplied to the stator 3 to generate a rotating magnetic field and rotate the rotor 5.

The configuration of the stator 3 and the rotor 5 will be described in detail. The stator 3 has a stator core 17. The stator core 17 is configured by punching electromagnetic steel sheets into a predetermined shape and laminating a predetermined number of electromagnetic steel sheets while being fastened with caulking.

Near the center of the stator 3, a shaft 13 that is rotatably held is disposed. The rotor 5 is fitted to the shaft 13. The rotor 5 has a rotor core 11, and the rotor core 11 is also configured by punching electromagnetic steel plates into a predetermined shape and laminating a predetermined number of electromagnetic steel plates while being fastened by caulking.

Between the rotor outer peripheral surface 25 and a hole side line 57 described later, there is an inter-wall thin portion 18 (see FIG. 3) having a uniform thickness. Each of these inter-electrode thin portions 18 serves as a leakage magnetic flux path between adjacent magnetic poles, and is preferably as thin as possible.

A plurality of permanent magnets 19 (for the number of poles) magnetized so that N poles and S poles are alternately provided are provided in the rotor core 11. Each of the permanent magnets 19 is composed of a sintered ferrite magnet, and is curved in an arc shape as viewed in FIG. 1, and is arranged so that the arc-shaped convex portion side faces the center side of the rotor 5. More specifically, the rotor core 11 has a number of magnet insertion holes 21 corresponding to the plurality of permanent magnets 19, and the corresponding permanent magnets 19 are inserted into the plurality of magnet insertion holes 21, respectively. .

The permanent magnet 19 is composed of a ferrite magnet. Since the ferrite magnet contains iron oxide (Fe ₂ O ₃ ) as a main component, it is cheaper than a rare earth magnet used in a general permanent magnet embedded electric motor, and the supply performance is stable. In addition, since the ferrite magnet is easy to form an arc-shaped magnet, a magnet that can be inserted into a magnet insertion hole having a reverse arc shape as in the present embodiment can be configured.

The plurality of permanent magnets 19 and the plurality of magnet insertion holes 21 are both configured in a reverse arc shape that is opposite to the arc of the rotor outer peripheral surface 25 when viewed in the radially inner and outer directions. That is, the plurality of permanent magnets 19 and the plurality of magnet insertion holes 21 are formed in an arc shape that is convex toward the center side of the rotor 5 (ie, a direction that is concave toward the radially outer side, ie, the rotor outer peripheral surface 25 side). As shown in FIG. 1, one permanent magnet 19 is inserted into one magnet insertion hole 21.

The number of magnetic poles of the rotor 5 is not limited as long as it is two or more. In this description, a six-pole configuration is shown as an example, and as shown in FIGS. 1 and 2, the rotor 5 is provided with six magnet insertion holes 21 spaced apart at equal angular intervals. ing. That is, the six magnet insertion holes 21 are arranged so as to be separated from the adjacent magnet insertion holes 21 at an angular interval of 60 degrees. Further, the six permanent magnets 19 are arranged so that the N pole and the S pole are alternately switched along the circumferential direction of the rotor with respect to the direction of the magnetic pole in the radial direction.

Next, details of the permanent magnet and the magnet insertion hole will be described. FIG. 3 is a diagram showing a curved aspect of the magnet insertion hole. FIG. 4 is a view showing a state in which a magnet is inserted into the magnet insertion hole in FIG. 3.

The permanent magnets 19 each have a magnet inner surface 43, a magnet outer surface 45, and a pair of magnet side surfaces 47. Further, each of the magnet insertion holes 21 has a hole inner line 53, a hole outer line 55, and a pair of hole side lines 57 as the outline of the hole when viewed from the plane having the rotation center line CL as a perpendicular line. . The magnet insertion hole 21 extends in the same cross-sectional shape in the direction in which the rotation center line CL extends.

In addition, “inside” and “outside” on the magnet inner side surface and the magnet outer side surface indicate whether they are the inner side or the outer side in the radial direction in a relative comparison with respect to the plane having the rotation center line CL as a perpendicular line. “Inside” and “Outside” in the hole inner line and the hole outer line also indicate whether they are the radially inner side or the outer side relative to the rotation center line CL as a perpendicular line. It shall be.

As shown in FIG. 4, when the permanent magnet 19 is inserted into the corresponding magnet insertion hole 21, a gap portion 61 is formed between the magnet side surface 47 and the hole side line 57, and the magnet outer surface 45. And the hole outside line 55 are in contact with each other, and the magnet inner side surface 43 and the hole inside line 53 are in contact with each other.

The hole outer line 55 is configured by a first arc having a radius r1. On the other hand, the hole inner line 53 is configured by a second arc having a radius r2. The first arc and the second arc protrude toward the rotation center of the rotor.

The center O1 of the first arc of radius r1 and the center O2 of the second arc of radius r2 are located on the magnetic pole center line ML of the corresponding magnetic pole, and the center O1 of the first arc of radius r1 is the radius It is located radially outward from the center O2 of the second arc of r2. The center O1 of the first arc with the radius r1 is located radially outside the rotor outer peripheral surface 25, and the center O2 of the second arc with the radius r2 is located radially inward of the rotor outer peripheral surface 25. is doing.

Further, when viewed in a cross section in which the rotation center line CL of the rotor 5 is a perpendicular line, that is, in FIG. 3, the permanent magnet 19 and the magnet insertion hole 21 are formed symmetrically with respect to the corresponding magnetic pole center line ML.

As shown in FIG. 3, the distance x1 in the magnetic pole center line ML direction between the center O1 of the first arc of radius r1 in the magnet insertion hole 21 and the rotation center line CL is the center O2 of the second arc of radius r2. And the distance x2 between the rotation center line CL and the magnetic pole center line ML. The distance x1−the distance x2 is larger than the radius r1 of the first arc and the radius r2 of the second arc. That is, the magnet insertion holes 21 are formed so as to satisfy the relationship of x1> x2 and x1-x2> r1-r2.

In order to explain the merits satisfying the above relationship of the dimensions of the magnet insertion hole 21, FIG. 4 shows a state where a magnet is inserted into the magnet insertion hole satisfying the above relationship. First, by satisfying x1> x2 described above, the thickness of the magnet is non-uniform, that is, the thickness at the center of the magnet is maximized, and the thickness of the magnet is reduced toward the end of the magnet. By adopting such a magnet shape, when the magnet tries to move inside the magnet insertion hole while the rotor is rotating, the magnet is caught inside the magnet insertion hole, so that the movement of the magnet inside the magnet insertion hole is suppressed. Can do. The larger the difference between x1 and x2, the greater the difference between the center thickness and the end thickness of the magnet insertion hole. Therefore, it can be said that the larger x1-x2 is, the more reliable the magnet fixing is. However, simply satisfying x1> x2 may cause the end of the magnet insertion hole on the rotor outer peripheral surface 25 side to be sharp. When the end of the magnet insertion hole on the rotor outer peripheral surface 25 side is sharp, the magnetoresistance of the thin portion that is the iron core portion between the end of the magnet insertion hole on the rotor outer peripheral surface 25 side and the rotor outer peripheral surface 25 Therefore, the magnetic flux leaks from the magnet, resulting in a deterioration in efficiency due to an increase in the magnetic flux leakage. Therefore, in the first embodiment, by setting the dimensions so as to satisfy x1-x2> r1-r2, the end of the magnet insertion hole on the rotor outer peripheral surface 25 side is prevented from being sharp, The large magnetic resistance of the thin portion 18 can be maintained and the generation of leakage magnetic flux can be suppressed.

According to the permanent magnet embedded type electric motor of the first embodiment described above, the following advantages are obtained. By making the magnet insertion hole and the permanent magnet into a reverse arc shape, the surface area of the magnet can be increased, so that the magnetic force can be improved and the magnet torque caused by the magnet magnetic flux can be increased. Further, by arranging the center of the radius of the first arc of the hole outer line and the center of the radius of the second arc of the hole inner line at different positions, the magnet thickness becomes uneven, and the magnet insertion hole Since the rotating magnet can be fixed without providing a magnet fixing protrusion (stopper) on the magnet, partial demagnetization at the magnet end due to the protrusion (stopper) is suppressed, and the demagnetization resistance of the magnet end is improved. Can be made. Furthermore, by expanding the gap 3 ≦ θ ≦ 5 [deg] in the circumferential direction from the tip of the magnet insertion hole, it is possible to suppress the leakage magnetic flux generated in the thin wall, and thus it is possible to improve the magnet torque by increasing the magnetic force. Moreover, since the ferrite magnet is excellent in arc-shaped formability, the reverse arc-shaped magnet as described above can be easily configured.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described. FIG. 5 is a diagram of the same mode as FIG. 4 regarding the second embodiment of the present invention. The second embodiment is configured in the same manner as the first embodiment described above except for the parts described below.

As shown in FIG. 5, in the second embodiment, the magnet insertion hole 22 is provided with recesses 46 at both ends of the hole outer line 55 (each end on the rotor outer peripheral surface 25 side). Each of the recesses 46 extends from the corresponding end of the hole outer line 55 along the rotor outer peripheral surface 25 toward the corresponding magnetic pole center line ML. The gap 62 between the magnet side surface 47 and the hole side line 57 is expanded as compared with the first embodiment by the presence of the recess 46.

The advantages similar to those of the above-described first embodiment are also obtained by the permanent magnet embedded electric motor of the second embodiment configured as described above. Further, in the second embodiment, since the gap is expanded as described above, the magnetic resistance of the thin electrode portion can be further increased. Therefore, the leakage flux can be reduced to achieve a more efficient permanent. A magnet-embedded electric motor can be obtained.

Embodiment 3 FIG.
Next, as a third embodiment of the present invention, a rotary compressor equipped with the above-described permanent magnet embedded electric motor according to the first or second embodiment will be described. In addition, although this invention includes the compressor carrying the permanent magnet embedded type electric motor of Embodiment 1 or Embodiment 2 mentioned above, the classification of a compressor is not limited to a rotary compressor. .

FIG. 6 is a longitudinal sectional view of a rotary compressor equipped with an embedded permanent magnet electric motor. The rotary compressor 100 includes an embedded permanent magnet electric motor 1 (electric element) and a compression element 103 in an airtight container 101. Although not shown, refrigerating machine oil that lubricates each sliding portion of the compression element 103 is stored at the bottom of the sealed container 101.

The compression element 103 includes, as main elements, a cylinder 105 provided in a vertically stacked state, a rotation shaft 107 that is a shaft that is rotated by the embedded permanent magnet electric motor 1, a piston 109 that is inserted into the rotation shaft 107, A vane (not shown) that divides the inside of the cylinder 105 into a suction side and a compression side, and a pair of upper and

lower frames

111 and 113 that are rotatably inserted into the rotary shaft 107 and close the axial end surface of the cylinder 105. , And mufflers 115 respectively mounted on the upper frame 111 and the lower frame 113.

The stator 3 of the permanent magnet embedded electric motor 1 is directly attached and held on the sealed container 101 by a method such as shrink fitting or welding. Electric power is supplied to the coil of the stator 3 from a glass terminal fixed to the sealed container 101.

The rotor 5 is disposed on the inner diameter side of the stator 3 via a gap, and a bearing portion (an upper frame 111 and a lower frame 113) of the compression element 103 via a rotation shaft 107 (shaft 13) at the center of the rotor 5. ) Is held in a freely rotatable state.

Next, the operation of the rotary compressor 100 will be described. The refrigerant gas supplied from the accumulator 117 is sucked into the cylinder 105 through a suction pipe 119 fixed to the sealed container 101. The permanent magnet embedded electric motor 1 is rotated by energization of the inverter, so that the piston 109 fitted to the rotating shaft 107 is rotated in the cylinder 105. Thereby, the refrigerant is compressed in the cylinder 105. After the refrigerant passes through the muffler 115, the refrigerant rises in the sealed container 101. At this time, refrigeration oil is mixed in the compressed refrigerant. When the mixture of the refrigerant and the refrigerating machine oil passes through the air holes 71 provided in the rotor core 11, the separation of the refrigerant and the refrigerating machine oil is promoted, and the refrigerating machine oil can be prevented from flowing into the discharge pipe 121. In this way, the compressed refrigerant is supplied to the high-pressure side of the refrigeration cycle through the discharge pipe 121 provided in the sealed container 101.

In addition, although conventional R410A, R407C, R22, etc. may be used as the refrigerant of the rotary compressor 100, any refrigerant such as a low GWP (global warming potential) refrigerant can be applied. From the viewpoint of preventing global warming, a low GWP refrigerant is desired. As typical examples of the low GWP refrigerant, there are the following refrigerants.
(1) Halogenated hydrocarbon having a carbon double bond in the composition: for example, HFO-1234yf (CF3CF = CH2). HFO is an abbreviation for Hydro-Fluoro-Olefin, and Olefin is an unsaturated hydrocarbon having one double bond. The GFO of HFO-1234yf is 4.
(2) Hydrocarbon having a carbon double bond in the composition: for example, R1270 (propylene). GWP is 3, which is smaller than HFO-1234yf, but flammability is larger than HFO-1234yf.
(3) 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 is there. Since HFO-1234yf is a low-pressure refrigerant, its pressure loss is large, and the performance of the refrigeration cycle (especially in an evaporator) tends to deteriorate. Therefore, a mixture with R32 or R41, which is a high-pressure refrigerant, is more effective than HFO-1234yf in practical use.

The rotary compressor according to the third embodiment configured as described above has the same advantages as those of the first embodiment described above. Also, since the compressor for refrigeration and air conditioning is used from low to high temperatures, motors using magnets whose coercive force decreases at low temperatures, such as ferrite magnets, must strictly evaluate the demagnetization resistance at low temperatures. There is. In this respect, the embedded permanent magnet electric motor of the present invention has improved demagnetization resistance at low temperatures, so that it has a more beneficial effect when mounted on a compressor for refrigerating and air conditioning used from low to high temperatures. Will be.

Embodiment 4 FIG.
The present invention can also be implemented as a refrigeration air conditioner including the above-described compressor according to the third embodiment as a component of the refrigeration circuit. In addition, the structure of components other than the compressor in the refrigeration circuit of the refrigeration air conditioner is not particularly limited.

Although the contents of the present invention have been specifically described with reference to the preferred embodiments, various modifications can be made by those skilled in the art based on the basic technical idea and teachings of the present invention. It is self-explanatory.

1 permanent magnet embedded motor, 3 stator, 5 rotor, 11 rotor core, 19 permanent magnet, 21, 22 magnet insertion hole, 25 rotor outer peripheral surface, 43 magnet inner surface, 45 magnet outer surface, 46 recess, 53 hole inner line , 55 outer hole line, 100 rotary compressor, 101 sealed container, 103 compression element.

Claims

A stator,
A rotor provided rotatably against the stator,
The rotor has a plurality of permanent magnets and a rotor core,
The rotor core has a plurality of magnet insertion holes,
The permanent magnet is inserted into the magnet insertion hole,
The outline of the magnet insertion hole includes a hole inner line and a hole outer line as viewed in a plane having the rotation center line CL of the rotor as a perpendicular.
The permanent magnet includes a magnet inner surface and a magnet outer surface,
The magnet inner surface is in contact with the hole inner line, the magnet outer surface is in contact with the hole outer line,
The hole inner line is constituted by a first arc having a radius r1, and the hole outer line is constituted by a second arc having a radius r2.
The first arc and the second arc protrude toward the rotation center of the rotor;
The center O1 of the first arc and the center O2 of the second arc are located on the magnetic pole center line ML,
The distance x1 between the center O1 of the first arc and the rotation center line CL in the magnetic pole center line ML direction is the magnetic pole center line ML between the center O2 of the second arc and the rotation center line CL. A distance x2 in the direction, and the distance x1−the distance x2 is larger than the radius r1−the radius r2.
Permanent magnet embedded motor.
The permanent magnet is a ferrite magnet,
The embedded permanent magnet electric motor according to claim 1.
The magnet insertion hole is provided with recesses at both ends of the hole outer line,
The concave portion extends from the corresponding end portion of the hole outer line along the outer peripheral surface of the rotor toward the corresponding magnetic pole center line ML.
The permanent magnet embedded type electric motor according to claim 1 or 2.
A compressor having an electric motor and a compression element in a sealed container,
The electric motor is an embedded permanent magnet electric motor according to any one of claims 1 to 3.
Compressor.
A refrigeration air conditioner comprising the compressor of claim 4 as a component of a refrigeration circuit.