HK1069927B - The permanent magnet type rotating electric machine - Google Patents

Description

Permanent magnet type rotary motor

Technical Field

The present invention relates to a permanent magnet type rotary electric machine having a rotor provided with a permanent magnet for excitation, and more particularly to an electric compressor constituting a cooling device provided in an air compressor, a refrigerator, a freezer, a showcase, or the like.

Background

In such a permanent magnet type rotary electric machine, a concentrated winding is used for the stator winding, and a rare earth neodymium permanent magnet is used for the magnetic field. As a countermeasure against this noise, for example, in an electric compressor described in japanese patent laid-open No. 2001-342954 (patent document 1), a proposal has been made to cut out an inner wall of a hermetic container of the compressor and an axial portion of an outer peripheral portion of a stator core in contact with the inner wall.

Patent document 1

Japanese unexamined patent application publication No. 2001-342954

In the above-described technology, there are 2 types of outer peripheral shapes of the outermost diameter of the stator core, and when the stator core is formed by in-mold lamination using a clamp (uneven bonding) formed by using a hollow mold (ホロ - ダィ) HAC, the stator core can be in-mold laminated while abutting against the inner wall of the pressure vessel, but there is a problem that the in-mold lamination cannot be performed without a reference position for the stator core that is not in abutment.

The in-mold lamination is performed by stacking the stator iron plates forming the stator core at a reference position on the outer periphery thereof without causing a displacement.

The invention provides a permanent magnet type rotary motor and an electric compressor which can realize assembly by in-mold lamination of a stator core and solve the problem of noise.

Disclosure of Invention

The present invention provides a permanent magnet type rotary motor, which comprises the following components: a cylindrical frame, a stator embedded and supported in the frame, a rotor rotatably arranged at the inner side of the stator, a permanent magnet arranged on the rotor, a stator core forming the stator, a stator winding wound on the stator core, and a plurality of laminated stator iron plates forming the stator core, wherein the stator core forms a combination body by combining concave and convex parts and the like; the stator core has a plurality of T-shaped parts and a plurality of slots arranged at two sides of the T-shaped parts, and the stator winding positioned in the slots is wound on the T-shaped parts; the outer diameters of the stator iron plates are different corresponding to the position of the lamination direction; an outer periphery of the stator iron plate with a large outer diameter is used as a contact part which is contacted with the inner periphery of the framework; a protruding abutting part abutting against the inner circumference of the frame is arranged on the outer circumference of the stator iron plate with a small outer diameter; the stator iron plate having a large outer diameter has a large abutting area of the abutting portion and the protruding abutting portion has a small abutting area.

Each stator iron plate has an abutting portion having a different abutting area depending on the position of the stator iron plate in the stacking direction (axial direction), and therefore, noise generated by the rotating electric machine can be reduced. Further, since the abutting portion is provided on the outer periphery of any of the stator iron plates, the stator iron plates can be assembled by in-mold lamination of the stator iron plates.

The present invention also provides a permanent magnet type rotary electric machine comprising a cylindrical frame, a stator embedded in and supported by the frame, a rotor rotatably provided inside the stator, a permanent magnet provided on the rotor, a stator core forming the stator, a stator winding wound around the stator core, and a plurality of laminated stator iron plates forming the stator core, wherein each of the stator iron plates has a contact portion on an outer periphery thereof, the contact portion being in contact with an inner periphery of the frame by a protrusion, and wherein a circumferential width of the contact portion is less than 1% of an outer peripheral length of the stator.

Drawings

Fig. 1 is a view showing a permanent magnet type rotating electrical machine according to embodiment 1 of the present invention, and is a cross-sectional view showing a radial cross-sectional shape.

Fig. 2 is a diagram showing a permanent magnet type rotating electric machine according to embodiment 1 of the present invention, and is a diagram mainly illustrating an axial sectional shape.

Fig. 3 is a sectional view showing an axial sectional shape of an electric compressor on which a permanent magnet type rotating electric machine according to embodiment 1 of the present invention is mounted.

Fig. 4 is a diagram showing a result of measuring noise of an electric compressor on which a permanent magnet type rotating electric machine according to embodiment 1 of the present invention is mounted.

Fig. 5 is a diagram showing an overall noise value of an electric compressor on which a permanent magnet type rotating electric machine according to embodiment 1 of the present invention is mounted.

Fig. 6 is a cross-sectional view showing a radial cross-sectional shape of a permanent magnet type rotating electrical machine 1 according to embodiment 2 of the present invention.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to fig. 1 to 6. Common symbols in the drawings denote the same thing. Here, a 4-pole permanent magnet type rotating electric machine is shown, in which the ratio of the number of poles of the rotor to the number of slots of the stator is 2: 3.

First, embodiment 1 of the present invention will be explained.

Fig. 1 shows a permanent magnet type rotary electric machine of embodiment 1 of the present invention, showing a radial sectional shape; fig. 2 shows a permanent magnet type rotary electric machine of embodiment 1 of the present invention, mainly showing its axial sectional shape; fig. 3 shows an axial sectional shape of an electric compressor on which a permanent magnet type rotating electric machine according to embodiment 1 of the present invention is mounted.

Fig. 1(a) shows a radial sectional shape of a stator core having a large diameter, and fig. 1(b) shows a radial sectional shape of a stator core having a small diameter (having a protrusion on the outer periphery). Fig. 1(a) differs from fig. 1(b) in the outer peripheral shape of the stator core.

As shown in fig. 1(a), a permanent magnet type rotating electrical machine 1 is composed of a stator 2 and a rotor 3. The stator 2 is composed of a stator core 6 and a concentrated-winding stator winding 8, the stator core 6 is composed of a T-shaped portion 4 and a core back 5, and the stator winding 8 (composed of a U-phase winding 8a, a V-phase winding 8b, and a W-phase winding 8c of three-phase windings) is wound in a slot 7 between the T-shaped portions 4 around the T-shaped portion 4. A semicircular recess 80 is provided on the outer periphery of the stator core 6 where the T-shaped portion 4 is located.

Here, since the permanent magnet type rotating electric machine 1 has 4 poles and 6 slots, the slot pitch is 120 ° in electrical angle. In the rotor 3, permanent magnet insertion holes 11 are formed near the outer peripheral surface of a rotor core 10 having a rotation shaft hole 9 for inserting a rotation shaft (not shown), and permanent magnets 12 made of rare earth neodymium are fixed to the permanent magnet insertion holes 11. Reference numeral 13 denotes an outermost periphery of the stator core, which is concentric with the rotation shaft.

In fig. 1(b), 14 is the outer periphery of the stator core, and is set to be slightly smaller in diameter than the outermost periphery 13 of the stator core. That is, the outer diameter is large at the outer periphery 13 of the stator core, and the outer diameter is formed small at the outer periphery 14 of the stator core.

If the outer periphery 14 of the stator core is made too small, the magnetic characteristics of the permanent magnet type rotating electric machine 1 are deteriorated, and therefore the diameter deviation between 13 and 14 is set within 1 mm.

Two projections 15 composed of 15a and 15b are formed outside the outer periphery 14 of the stator core, and the outer peripheral surface of the projection 15 is set to have the same diameter as the outermost periphery 13 of the stator core. Here, 2 projections 15 are provided on the outer periphery of each slit 4 (the outer periphery between the recesses 80), but only 1 projection may be provided, or any number may be provided.

The outer periphery 13 and the outer periphery 14 of the stator core are described in detail with reference to fig. 2.

Fig. 2(a) shows a combination of the outermost periphery 13 of the stator core and the outer periphery 14 of the stator core of the permanent magnet type rotating electric machine 1 of fig. 1, fig. 2(B) shows a half cross section of the axial sectional shape a-a 'of fig. 2(a), and fig. 2(c) shows a half cross section of the axial sectional shape B-B' of fig. 2 (a). A-A 'is a cross section at the center of the T-shaped portion 4, and B-B' is a cross section at the center of the notch 7.

In fig. 2 b, the rotor core 10 of the rotor 3 is fixed to the rotating shaft 16 by shrink fit, and the stator core outermost periphery 13 of the stator 2 is fixed to the frame 30 by shrink fit (see fig. 3).

In contrast, in fig. 2(c), the outermost periphery 13 of the stator core of the stator 2 is fixed to the frame 30 by shrink-fitting only along the axial length La, and as a result of the projection 15 being fixed to the frame 30 by shrink-fitting, the outer periphery 14 of the stator core is separated from the frame 30 only along the axial length (Lb-La). That is, the outermost periphery 13 of the stator core is in contact with the inner peripheral surface of the frame 30 by shrink fitting except for the recess 80. On the other hand, at the outer periphery 14 of the stator core, only the protrusions 15 are in contact with the inner peripheral surface of the frame 30 by shrink fitting, and the other portions are separated from the frame 30.

In other words, the stator core 10 is formed by stacking a plurality of stator iron plates, and the outer periphery of any one of the stator iron plates abuts against the inner peripheral surface of the frame 30. However, the contact area of the contact portion with the inner peripheral surface of the frame 30 differs depending on the stacking direction (axial direction) position of the stack. Since the outermost periphery 13 of the stator core is in contact with the recess 80, the contact area of the contact portion is large; on the other hand, at the outer periphery 14 of the stator core, only the protrusions 15 (protrusion-shaped contact portions) contact each other, so that the contact area of the contact portions is small.

That is, although the outer periphery of any of the stator iron plates abuts against the inner periphery of the frame, the abutting area of the abutting portion is different (larger or smaller) depending on the position in the stacking direction (axial direction) of the stator iron plates. In example 1 shown in fig. 1 and 2, the contact area of the contact portion is large at the intermediate position in the lamination direction (axial direction) of the stator iron plates; on the other hand, the contact area of the contact portion is small on both end sides in the stacking direction (axial direction).

Fig. 3 shows a sectional shape of an electric compressor incorporating the permanent magnet type rotating electric machine 1 of the present invention.

In fig. 3, the electric compressor 40, the external appearance is formed with a housing. The casing is composed of a cylindrical frame 30, an upper cover 31 on the upper end side, and a lower cover 32 on the lower end side. The frame 30 becomes a sealed container.

The frame 30 houses an electric element serving as the permanent magnet type rotating electric machine 1 and a compression element 50 called a scroll compressor.

The frame 30 is formed by bending a plate-shaped steel plate into a cylindrical shape. The upper and lower ends of the frame 30 are closed by an upper cover 31 and a lower cover 32 to form a closed container. The upper cover 31 and the lower cover 32 are welded to the frame 30 to form a sealed structure.

The compression element 50 is formed by meshing a spiral wrap 53 standing upright on an end plate 52 of the fixed scroll 51 and a spiral wrap 56 standing upright on an end plate 55 of the orbiting scroll 54, and performs compression operation by rotating the orbiting scroll 54 by the crank shaft 16.

Of the compression chambers 57(57a, 57b, …) formed by the fixed scroll 51 and the orbiting scroll 54, the compression chamber located on the outermost diameter side gradually decreases in volume as it moves toward the center of the scroll 51, 54 with the orbiting motion. When the compression chambers 57a and 57b reach the vicinity of the centers of the scroll members 51 and 54, the gas sucked from the suction pipe 58 in the compression chambers 57 is compressed in the compression chambers 57, and the compressed gas is discharged from the discharge port 59 communicating with the compression chambers 57.

The discharged compressed air passes through the fixed scroll 51 and a gas passage (not shown) provided in the fixed member 60, reaches the inside of the member 30 below the fixed member 60, and is discharged from a discharge pipe 61 provided in a side wall of the frame 30 to the outside of the electric compressor 40.

The permanent magnet type rotary electric machine 1 (electric element) constituting the electric compressor 40 is controlled by an inverter (ィンズ - タ) (not shown) provided separately and rotated at a rotation speed suitable for the compression operation. Here, the permanent magnet type rotating electrical machine 1 is composed of a stator 2 and a rotor 3. The upper side of the rotating shaft 16 provided in the rotor 3 becomes a crank shaft. An oil hole 62 is formed in the rotating shaft 16, and by the rotation of the rotating shaft 16, the lubricating oil in the oil reservoir 63 in the lower portion of the frame 30 is supplied to a slide bearing type upper bearing portion 64 and a ball bearing type lower bearing portion 65 through the oil hole 62. Reference numeral 66 denotes a terminal for supplying power from the transformer to the stator winding 8. And 67 is a base.

Here, the frame 30 is a cylindrical bent plate-shaped steel plate, and the accuracy of the circumferential diameter dimension of the inner circumference is not strict, and the diameter dimension usually varies within a range of ± 20 μm. As a result, the stator core 6 of the stator 2 that is thermocompression-fitted into the frame 30 cannot define where the inner periphery of the frame 30 contacts the outer periphery of the stator core 6. Therefore, fig. 3 shows the radial cross-sectional shape of the permanent magnet type rotating electrical machine 1 shown in fig. 2(c), but the outermost periphery 13 (having a large outer diameter) of the stator core is in contact with the frame 30, and the outer periphery 14 (having a small outer diameter) of the stator core is not in contact with the frame 30. Further, there is a protrusion 15 on the outer periphery of the stator core outer periphery 14, and the outer periphery of the protrusion 15 is in contact with the inner periphery of the frame 30 since it has the same diameter as the outermost periphery 13 of the stator core. Therefore, any of the stator iron plates constituting the stator core 6 is in contact with (abuts on) the inner periphery of the frame 30. However, the contact area of the contact portion is large at the intermediate position in the lamination direction (axial direction) of the stator iron plates, and the contact area of the contact portion is small at both ends in the lamination direction (axial direction).

Fig. 4 is a graph showing the noise measured in the electric compressor 40. The electric compressor 40 has a cooling/heating capacity of 2.2kw to 2.8kw, and operates by enclosing a refrigerant R410A. The measurement microphone was located at the axial center of the permanent magnet type rotating electric machine 1 and separated by 1 m.

In fig. 4, the horizontal axis represents frequency components and the vertical axis represents noise, and measurement data of the conventional electric compressor and the electric compressor of the present invention are shown together. In addition, in the conventional electric compressor, a structure in which the outer peripheries of the stator cores are in contact with each other in the stacking direction (axial direction) is used.

As shown in fig. 4, the noise of the electric compressor of the present invention is larger than that of the conventional art for the 200Hz and 250Hz components, but the noise of the electric compressor of the present invention is smaller than that of the conventional art for the frequency components above the above. Fig. 5 shows the integrated value (OA) of the noise. As shown in fig. 5, the noise of the motor-driven compressor of the present invention is lower by 1.7dB than that of the prior art.

Such noise reduction is caused by increasing the contact area of the contact portion at the intermediate position in the lamination direction (axial direction) of the stator iron plates and decreasing the contact area of the contact portion at both ends in the lamination direction (axial direction), and the contact portion will be described with respect to the assembly of the stator core 6.

Of course, the stator iron plates punched out by the press are laminated to manufacture the stator core 6, and the lamination is performed in a lamination die called a hollow die.

A stator iron plate corresponding to an outermost periphery 13 (having a larger outer diameter) of the stator core, the outer diameter of which is in conformity with the inner diameter of the lamination mold; however, since the outer diameter of the stator iron plate corresponding to the outer periphery 14 (smaller outer diameter) of the stator core is small, a gap is formed between the outer periphery and the inner periphery of the lamination mold. However, the protrusions 15 are provided on the outer periphery of the stator iron plate corresponding to the outer periphery 14 (having a small outer diameter) of the stator core, and the outer periphery of the protrusions 15 has the same diameter as the outermost periphery 13 (having a large outer diameter) of the stator core. Therefore, even if the stator iron plates have a small outer diameter, they can be stacked in a very aligned state in the stacking direction (axial direction) without being displaced in the radial direction in the stacking mold, as in the case of the stator iron plates corresponding to the outermost periphery 13 (having a large outer diameter) of the stator core.

Thus, a stator core can be provided in which noise is reduced and which can be laminated using a lamination mold called a hollow mold.

The stator iron plates laminated in the mold are clamped (concavo-convex combination) by the HAC to form a firmly combined body (stator core).

The stator winding 8 is wound around the stator 2 formed by the stator core 6 and fixed in the frame 30 by shrink-fitting. The upper and lower sides of the stator core 6 are also fixed in the frame 30 by shrink-fitting of the protrusions 15. However, since the contact area of the projection 15 is small, strong fixation cannot be expected. The intermediate position (the position where the outermost periphery 13 of the stator core (the outer diameter is large)) in the lamination direction (the axial direction) of the stator core 6 contributes to the actual fixation. The upper and lower sides of the stator core 6 are not strongly fixed to the frame 30, but the stator iron plates are not scattered, and are strongly bonded by HAC clamping (uneven bonding).

The following describes embodiment 2 of the present invention.

Fig. 6 shows a permanent magnet type rotating electrical machine 1 according to embodiment 2 of the present invention. Fig. 6 shows the same sectional shape as that shown in fig. 2 (c).

In fig. 6, the stator core outermost periphery 13 of the stator 2 is fixed to the left end of the frame 30 by shrink fitting only by the axial length La, and as a result (not shown in the drawings) of the projection 15 being fixed to the frame 30 by shrink fitting, the stator core outer periphery 14 is separated from the frame 30 by only the axial length (Lb-La). This also achieves the same effect as in fig. 1, and reduces noise of the electric compressor.

In fig. 6, the stator core outermost periphery 13 of the stator 2 is fixed to the left end of the frame 30 only by the axial length La by shrink fitting, but similar effects can be obtained even if it is provided at the right end. However, when the stator core outermost peripheries 13 of the stator 2 are disposed on both sides of the frame 30, the center portion is in a state where the stator core outer periphery 14 is separated from the frame 30. In this regard, the effect of noise reduction cannot be confirmed. The reason for this is not clear, but in the case of press-fitting the stator into the frame formed into a cylindrical shape by bending a plate, the accuracy of the inner peripheral circular tube is not strict, and usually varies by ± 20 μm in diameter. As a result, the stator 2 that is shrink-fitted into the frame 30 cannot define where the inner periphery of the frame 30 contacts the outer periphery of the stator core 6, and it is estimated that noise cannot be reduced because the stator contacts both sides of the frame 30 in the axial direction.

The permanent magnet type rotary electric machine 1 used in the electric compressor of the present invention has a stator outer diameter of 105mm, a lamination thickness of 45mm, La of 20mm, and a circumferential width of the full protrusion 15 of less than 1% of an outer circumference of the stator. The compressor was subjected to a drop test, and when the stator 2 was displaced from the shrink-fit position of the frame 30 by the impact at the time of the drop, the standard was not satisfied. Therefore, the results of the drop test performed with the stator lamination thickness varied are: a lamination thickness of 15mm (33.3% of the full lamination thickness) was acceptable, but a lamination thickness of 13mm (28.9% of the full lamination thickness) was not. In addition, as a result of the noise test, when La was 30mm (66.7% of the total lamination thickness), the noise reduction effect was obtained; however, when La was 35mm (77.8% of the total lamination thickness), the noise reduction effect was not obtained. Therefore, La is most preferably in the range of 33% or more and less than 67% of the total lamination thickness in order to obtain sufficient strength and noise reduction effect.

The compressor shown in fig. 3 is called a scroll compressor, and unlike the scroll compressor, there is a rotary compressor having a structure in which an electric element is located on the upper side and a compression element is located on the lower side. Such a rotary compressor has a structure without a bearing on the upper side. This is to reduce the manufacturing cost thereof. Also, the permanent magnet type rotary electric machine of the present invention can be applied to such a rotary compressor.

That is, in a sealed electric compressor such as a scroll compressor or a rotary compressor, the present invention is applicable as an electric element that contributes substantially to fixing of the stator core 6 and in which the lamination thickness of the outermost periphery 13 portion is 33% or more and less than 67% of the lamination thickness of the stator core 6. Further, in order to improve the impact resistance of the stator core 6, it is not out of the scope of the present invention to apply the electric element, in which the lamination thickness of the outermost periphery 13 portion is 12% or more and less than 67% of the lamination thickness of the stator core 6, to the hermetic electric compressor by adopting a fixing structure such as spot welding in which the frame 30 and the outermost periphery 13 are integrated and the frame 30 is protruded inward. In the case of adopting a fixing structure such as spot welding, when a safety factor is considered for safety, it is preferable that the laminated thickness of the portion having the outermost periphery 13 is an electric element of 20% to 30% of the laminated thickness of the stator core 6. In this case, the number of fixing structures to be provided may be as long as the minimum number of fixing structures is required to achieve the strength required for the hermetic motor-driven compressor.

According to the above embodiment, by making the abutting portion as the protruding portion, noise can be reduced. In addition, by making the circumferential width of the abutting portion smaller than 1% of the outer circumferential length of the stator, noise can be further reduced.

As described above, according to the present invention, a permanent magnet type rotating electric machine and an electric compressor can be provided in which a stator core can be assembled by in-mold lamination and which are low in noise.

Claims (7)

1. A permanent magnet type rotary electric machine comprising: a cylindrical frame, a stator embedded and supported in the frame, a rotor rotatably provided inside the stator, a permanent magnet provided on the rotor, a stator core forming the stator, a stator winding wound around the stator core, and a plurality of laminated stator iron plates forming the stator core,

the stator core is formed by a plurality of stator iron plates into a combined body;

the stator core has a plurality of T-shaped parts and a plurality of slots arranged at two sides of the T-shaped parts, and the stator winding positioned in the slots is wound on the T-shaped parts;

the outer diameters of the stator iron plates are different corresponding to the position of the lamination direction;

an outer periphery of the stator iron plate with a large outer diameter is used as a contact part which is contacted with the inner periphery of the framework;

a protruding abutting part abutting against the inner circumference of the frame is arranged on the outer circumference of the stator iron plate with a small outer diameter;

the stator iron plate having a large outer diameter has a large abutting area of the abutting portion and the protruding abutting portion has a small abutting area.

2. A permanent magnet type rotating electrical machine according to claim 1, wherein the stator iron plate having a large outer diameter is disposed at an intermediate position in the stacking direction; the stator iron plates having small outer diameters are disposed at positions on both end sides in the stacking direction.

3. A permanent magnet type rotating electrical machine according to claim 1, wherein the stator iron plate having a large outer diameter is disposed at one side position in the stacking direction; the stator iron plates having small outer diameters are arranged at positions opposite to each other in the stacking direction.

4. A permanent magnet type rotating electrical machine according to any one of claims 1 to 3, wherein the lamination thickness of the stator iron plate having the larger contact area is 33% to 67% of the total lamination thickness of the stator core.

5. A permanent magnet type rotating electrical machine according to any one of claims 1 to 3, wherein the lamination thickness of the stator iron plate having the larger contact area is 12% to 67% of the total lamination thickness of the stator core.

6. A permanent magnet type rotating electrical machine according to any one of claims 1 to 3, wherein the lamination thickness of the stator iron plate having the larger contact area is 20% to 30% of the total lamination thickness of the stator core.

7. A permanent magnet type rotary electric machine having a cylindrical frame, a stator embedded in and supported by the frame, a rotor rotatably provided inside the stator, a permanent magnet provided on the rotor, a stator core forming the stator, a stator winding wound around the stator core, and a plurality of laminated stator iron plates forming the stator core, each of the stator iron plates having an abutting portion on an outer periphery thereof, the abutting portion abutting an inner periphery of the frame by a protrusion,

the circumferential width of the abutting portion is less than 1% of the outer circumference of the stator.