KR101925333B1 - Electric motor with permanent magnet and compressor having the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor having a permanent magnet and a compressor having the same, wherein the electric motor having the permanent magnet includes a stator; And a rotor rotatably disposed with an air gap with respect to the stator, wherein the rotor has a rotating shaft and a permanent magnet, wherein a surface of the permanent magnet facing the gap is a pole anisotropic magnet so that a magnetic field is formed, And a profile formed such that the outer diameter gradually increases from the center of the magnetic pole toward both ends. Thereby, the mass of the rotor can be reduced, the ripple can be reduced, and the occurrence of vibration and noise due to the ripple can be suppressed.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an electric motor having a permanent magnet,

The present invention relates to an electric motor having a permanent magnet and a compressor having the electric motor.

As is well known, an electric motor is an apparatus that converts electrical energy into mechanical energy.

Electric motors are classified into direct current, single-phase alternating current, and three-phase alternating current according to the electric supply system.

Such an electric motor generally comprises a stator and a rotor provided to the stator so as to be relatively movable with a predetermined gap therebetween.

Some of the rotors include a rotor core having a rotating shaft, a plurality of conductor bars inserted in the rotor core in the axial direction, and an end ring for shorting the conductor bars.

Another part of the rotor is constituted by a permanent magnet and a rotor frame having a rotating shaft and supporting the permanent magnet.

However, in such a conventional electric motor having a permanent magnet, a magnetic body (back yoke) is provided so as to form a flux path (magnetic path) behind the permanent magnet, thereby increasing the mass of the rotor .

Vibration and noise can be increased when the mass of the rotor is increased.

In addition, when the mass of the rotor is increased, inertia of the rotor is increased, which makes it difficult to control start and stop.

In addition, the magnetic material may be formed of a magnetic steel sheet (or an electromagnetic steel sheet or a silicon steel sheet) having a high magnetic property and a high production cost, so that the manufacturing cost may be increased.

In addition, permanent magnets magnetized in the thickness direction (radial direction) so that different magnetic poles (N poles, S poles) are alternately arranged along the circumferential direction can not form a desirable sinusoidal (sinusoidal) magnetic field, So-called " two-sided " magnetic field is formed on both sides and the cogging torque is increased.

In consideration of such a problem, in some motors, a method of post-machining a permanent magnet so as to increase voids at both ends compared to the center of each magnetic pole of the permanent magnet is used.

However, when the voids at both ends of each of the magnetic poles of the permanent magnets described above are post-processed to increase, there is a problem in that not only the processing cost is increased but also the material consumption of the permanent magnets is increased.

KR 200238302 Y1 KR 101348717 B1

Accordingly, it is an object of the present invention to provide an electric motor having a permanent magnet capable of reducing a mass of a rotor and capable of reducing ripples, and a compressor having the same.

It is another object of the present invention to provide an electric motor having a permanent magnet capable of reducing the amount of material used for permanent magnets and a compressor having the permanent magnet.

It is still another object of the present invention to provide an electric motor having a permanent magnet capable of reducing ripples and increasing output density, and a compressor having the same.

In order to achieve the above object, the present invention provides a stator comprising: a stator; And a rotor rotatably disposed with an air gap with respect to the stator, wherein the rotor has a rotating shaft and a permanent magnet, wherein a surface of the permanent magnet facing the gap is a pole anisotropic magnet so that a magnetic field is formed, The magnet includes a plurality of magnetic pole portions alternately arranged in a circumferential direction with different magnetic poles alternately arranged such that the outer surface gradually increases in outer diameter from the center of each of the plurality of magnetic pole portions toward both ends, Wherein the profile of the permanent magnet is provided by a profile of the permanent magnet.

According to an embodiment of the present invention, the rotor further comprises a rotor frame connecting the rotating shaft and the permanent magnet.

According to an embodiment of the present invention, the permanent magnets are formed to have the same thickness so that the inner surface corresponds to the shape of the outer surface.

According to an embodiment of the present invention, the inner surface of the permanent magnet is formed to have an inner diameter that increases from the center of the plurality of magnetic pole portions toward both ends, or is formed to have the same shape as the outer surface.

According to an embodiment of the present invention, the permanent magnet is configured such that the thickness of the center of the plurality of magnetic pole portions is 90% to 100% of the thickness of the both end portions of the plurality of magnetic pole portions.

According to an embodiment of the present invention, the difference between the maximum outer diameter and the minimum outer diameter of the permanent magnet is 20% to 30% of the thickness of the permanent magnet.

According to an embodiment of the present invention, the outer surface of the rotor frame has a shape corresponding to the shape of the inner surface of the permanent magnet.

According to an embodiment of the present invention, the rotary shaft and the rotor frame are made of different materials.

The rotor frame is configured to be injection-molded around the rotation shaft.

According to an embodiment of the present invention, the permanent magnet is composed of a bonded magnet.

According to an embodiment of the present invention, the rotor frame is formed to have a profile extending along a circumferential direction so as to gradually decrease from a position having an outer diameter of a maximum outer diameter to a position having a minimum outer diameter.

According to another aspect of the present invention, A compression unit provided inside the case and compressing the fluid; And a motor provided inside the case and having the permanent magnet for providing a driving force to the compression portion.

As described above, according to the embodiment of the present invention, the permanent magnets are pole-anisotropic so as to form a magnetic field on the surface facing the gap, and the different poles are arranged alternately, and the outer surface of each magnetic- The rotor frame can be formed of a lightweight material that does not form a magnetic path, so that the mass of the rotor can be reduced.

Further, the magnetic flux density of the air gap has a sinusoidal (sinusoidal) shape, so that the ripple (cogging torque and torque ripple) can be reduced, and generation of vibration and noise due to the ripple can be suppressed.

In addition, since the permanent magnet is integrally injection-molded, the post-machining can be eliminated, and loss of the permanent magnet material due to post-machining can be suppressed.

As a result, the cost of post-processing of the permanent magnet can be reduced, and the amount of material input to the permanent magnet can be reduced.

In addition, since the inner surface of the permanent magnet is formed to be the same as the outer surface shape, a magnetic path can be secured so that each magnetic pole portion corresponds to the movement pattern of the magnetic flux, and the magnetic flux density can be enhanced.

Thus, the output density (performance) of the electric motor can be improved.

1 is a cross-sectional view of a compressor including a motor having permanent magnets according to an embodiment of the present invention;
Figure 2 is an enlarged view of the rotor of Figure 1,
Figure 3 is a top view of the rotor of Figure 2,
Fig. 4 is an enlarged view of the permanent magnet of Fig. 3,
Fig. 5 is an enlarged view of the main part of the permanent magnet shown in Fig. 4,
Fig. 6 is an enlarged view of the rotor frame of Fig. 3,
7 is a sectional view of a rotor of a motor having permanent magnets according to another embodiment of the present invention,
Figure 8 is a top view of the rotor of Figure 7,
Fig. 9 is an enlarged view of the permanent magnet of Fig. 8,
FIG. 10 is a graph showing the void magnetic flux density of the permanent magnet of FIG. 1,
11 is a graph showing the pore magnet density of the permanent magnet of Fig. 7;

Hereinafter, embodiments disclosed in this specification will be described in detail with reference to the accompanying drawings. In this specification, the same or similar reference numerals are given to the same or similar components in different embodiments, and the description thereof is replaced with the first explanation. As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. In the following description of the embodiments of the present invention, a detailed description of related arts will be omitted when it is determined that the gist of the embodiments disclosed herein may be blurred. In addition, it should be noted that the attached drawings are only for easy understanding of the embodiments disclosed in the present specification, and should not be construed as limiting the technical idea disclosed in the present specification by the attached drawings.

1 is a cross-sectional view of a compressor having an electric motor having permanent magnets according to an embodiment of the present invention, and FIG. 2 is an enlarged view of the rotor of FIG.

As shown in Figs. 1 and 2, a compressor including an electric motor having permanent magnets of this embodiment includes a casing 110; A compression unit 130 installed in the case 110 to compress the fluid; And a motor 150 having a permanent magnet according to an embodiment of the present invention, which is provided inside the case 110 and provides a driving force to the compression unit 130.

The case 110 may be configured to form, for example, a receiving space therein.

The case 110 may, for example, be formed with an enclosed accommodation space inside.

The case 110 may include a cylindrical body 111 and a cap coupled to the opening of the body 111 to block the opening.

The body 111 may be formed such that both sides thereof are open.

The cap may include, for example, a first cap 113 and a second cap 115 for blocking both sides of the body 111.

The first and second caps 113 and 115 may be coupled to upper and lower portions of the body 111, respectively.

A suction pipe 117 may be provided on one side of the case 110.

A discharge pipe 119 may be provided on the other side of the case 110.

Oil 121 may be provided in the case 110.

The oil 121 may be injected at a predetermined height into the inner bottom of the case 110.

The compression unit 130 may be installed in the lower portion of the case 110.

The compression unit 130 may be installed to communicate with the suction pipe 117.

As a result, the refrigerant outside the case 110 can be sucked into the compression unit 130.

The refrigerant in the case 110 may be discharged to the outside of the case 110 through the discharge pipe 119.

Meanwhile, the compression unit 130 may include, for example, a cylinder 131 that forms a compression space for a refrigerant therein, and a roller 135 that compresses the refrigerant while rotating inside the cylinder 131 have.

The cylinder 131 may be formed such that both sides thereof are open.

The cylinder 131 may be formed such that the upper side and the lower side of the cylinder 131 are respectively opened.

The compression unit 130 may include a main bearing 137 and a sub bearing 139 which are coupled to the upper and lower sides of the cylinder 131, respectively.

The main bearing 137 may include a blocking portion 138a for blocking the cylinder 131 and a bearing portion 138b projecting from the blocking portion 138a.

The blocking portion 138a of the main bearing 137 may be configured to be extended from the cylinder 131 and fixedly coupled to the inside of the case 110, for example.

The sub bearing 139 may include a blocking portion 140a for blocking the cylinder 131 and a bearing portion 140b projecting from the blocking portion 140a.

The rotating shaft 185 of the electric motor 150 is received and rotatably supported in the bearing portion 138b of the main bearing 137 and the bearing portion 140b of the sub bearing 139, respectively.

The electric motor 150 having a permanent magnet according to an embodiment of the present invention may be provided in the case 110. The electric motor 150 may include a permanent magnet.

The electric motor 150 may include a stator 160 and a rotor 180 rotatably disposed with a predetermined gap G between the stator 160 and the stator 160.

The stator 160 may include, for example, a stator core 161 and a stator coil 171 wound around the stator core 161.

The stator core 161 may include, for example, a rotor receiving hole 163 in which the rotor 180 is rotatably received.

The stator core 161 may be formed by inserting a plurality of electrical steel plates 162 having the rotor accommodating holes 163 therein.

The stator core 161 may have a plurality of slots 166 and pawls 167 alternately arranged along the circumferential direction of the rotor accommodating hole 163.

The rotor 180 includes a rotating shaft 185, a permanent magnet 190 disposed concentrically with the rotating shaft 185, and a rotor 180 disposed between the rotating shaft 185 and the permanent magnet 190. [ And a frame 221 may be provided.

The rotation shaft 185 may have a length long enough to be coupled to the roller 135 and coupled to the rotor frame 221 at the other end.

The rotary shaft 185 may be provided with an eccentric portion 188 to allow the roller 135 to be engaged and eccentrically move.

A through hole 187 may be formed in the rotating shaft 185.

Accordingly, the oil at the bottom of the rotary shaft 185 can be moved upward through the through hole 187 when the rotary shaft 185 rotates.

Fig. 3 is a plan view of the rotor of Fig. 2, and Fig. 4 is an enlarged view of the permanent magnet of Fig.

The permanent magnet 190 may have a substantially cylindrical shape.

The permanent magnet 190 may be formed to have a magnetic field on a surface facing the gap G and to be a polar anisotropic magnet so that a magnetic field is not formed on the surface opposite to the gap G. [

The permanent magnet 190 may include a plurality of magnetic pole portions 193 that are alternately arranged with different magnetic poles along the circumferential direction.

The plurality of magnetic pole portions 193 may be equally spaced (equiangular) along the circumferential direction of the permanent magnet 190.

The number of the plurality of magnetic pole portions 193 may be appropriately adjusted so that the number of the plurality of magnetic pole portions 193 may be appropriately adjusted. In the present embodiment, the permanent magnet 190 is configured to have eight magnetic pole portions 193, have.

Each of the plurality of magnetic pole portions 193 may have a profile formed such that the outer diameter gradually increases from the center of the magnetic pole portion 193 toward both end portions.

The outer surface 191 of the permanent magnet 190 may have a shape in which the center of each of the magnetic pole portions 193 is periodically recessed inward.

The plurality of magnetic pole portions 193 of the permanent magnet 190 include a plurality of first magnetic pole portions 193a and a plurality of second magnetic pole portions 193a, And a second magnetic-pole portion 193b.

More specifically, for example, the first magnetic-pole portion 193a may be configured such that the S-pole is formed at the left end portion and the N-pole is formed at the right end portion along the clockwise direction in the drawing.

The second magnetic-pole portion 193b may be configured such that an N-pole is formed at the left end portion and an S-pole is formed at the right end portion along the clockwise direction in the drawing.

The permanent magnet 190 may be formed such that the first magnetic pole portion 193a and the second magnetic pole portion 193b are alternately arranged along the circumferential direction.

The permanent magnet 190 may include four first magnetic-pole portions 193a and four second magnetic-pole portions 193b.

Fig. 5 is an enlarged view of the main part of the permanent magnet of Fig. 4, and Fig. 6 is an enlarged view of the rotor frame of Fig.

The plurality of magnetic pole portions 193 of the permanent magnet 190 may have a minimum outer diameter Domin at the center and a maximum outer diameter at both ends.

The permanent magnet 190 may have the same thickness and the inner surface 192 may have the same profile as the outer surface 191.

The permanent magnet 190 may be configured such that the inner surface 192 has a minimum inner diameter Dimin at the center of the magnetic pole portion 193 and a maximum inner diameter Dimax at both ends.

The magnetic flux density of the gap G is maximized at both ends of each of the magnetic pole portions 193 and the magnetic gap of the gap G at the center of each of the magnetic pole portions 193 is maximized. The magnetic flux density can be minimized.

As a result, the graph of the magnetic flux density of the gap G has a sinusoidal waveform (sine wave), so that ripples (cogging torque and torque ripple) can be reduced.

Thereby, generation of vibration and noise due to the ripple can be suppressed.

The permanent magnet 190 may have a maximum thickness t at both ends of the magnetic pole portions 193.

The permanent magnet 190 may have a minimum thickness t1 at the center of each of the magnetic pole portions 193.

That is, the permanent magnet 190 may be configured to have the same thickness t when the inner surface 192 has the same profile as the outer surface 191, The center thickness t1 may be formed to be smaller than the thickness t of both ends of the magnetic pole portions 193.

For example, the permanent magnet 190 has a maximum thickness t of the permanent magnets 190, and a difference t2 between the maximum outer diameter Dom and the minimum outer diameter Domin of the permanent magnets 190, 20 to 30%.

The permanent magnet 190 may be configured such that the thickness t1 of each magnetic pole portion 193 is in a range of 90% to 100% of the maximum thickness t of the permanent magnet 190 .

More specifically, for example, when the maximum thickness t of the permanent magnet 190 is 3 mm, the maximum outer diameter (Domax) and the minimum outer diameter (center) of the magnetic pole portions 193 of the permanent magnet 190 The pitch t2 of the grooves may be 0.6 mm to 0.9 mm.

According to such a configuration, the magnetic flux density of the gap G is maximized in the boundary region between the first magnetic pole portion 193a and the second magnetic pole portion 193b, and the magnetic pole portions 193 , The magnetic flux density of the gap G is relatively reduced, and the graph of the magnetic flux density of the gap G may have a sinusoidal (sinusoidal) shape.

As a result, the ripple (torque ripple) of the electric motor 150 is reduced, and vibration and noise caused by the ripple can be suppressed.

The thickness t1 of the center of each magnetic pole portion 193 of the permanent magnet 190 is set to 3 mm when the outer surface 191 and the inner surface 192 of the permanent magnet 190 have the same profile .

The thickness of the center of each magnetic pole portion 193 of the permanent magnet 190 may be 2.7 mm to 3 mm.

A rotor frame 221 for rotatably supporting the permanent magnet 190 may be provided between the permanent magnet 190 and the rotary shaft 185.

Since the permanent magnet 190 has a magnetic field formed on the outer surface 191 and does not form a magnetic field on the inner surface 192 of the rotor frame 221, the rotor frame 221 forms a magnetic path It may be formed as a non-magnetic material.

The rotor frame 221 may be formed of, for example, a non-magnetic material of a lightweight material.

The rotor frame 221 may be formed of, for example, a synthetic resin member.

The rotor frame 221 may be formed of the same material as the rotating shaft 185, for example.

The rotor frame 221 may be implemented in a substantially cylindrical shape, as shown in FIG.

The outer surface of the rotor frame 221 may have a shape corresponding to (identical to) the inner surface 192 of the permanent magnet 190, for example.

The outer surface 222 of the rotor frame 221 has a minimum outer diameter Domin at a corresponding point corresponding to the center of each magnetic pole portion 193 of the permanent magnet 190, And the outer diameter gradually increases to have a profile having a maximum outer diameter (Domax) at both ends.

A rotating shaft hole 223 may be formed at the center of the rotor frame 221 so as to insert the rotating shaft 185 therein.

The rotor frame 221 may include a plurality of penetrating portions 225 penetrating axially between the rotating shaft hole 223 and the outer surface 222.

Thereby, the mass of the rotor frame 221 can be reduced.

In addition, the upper and lower sides of the rotor 180 communicate with each other through the penetration portion 225, so that the fluid between the upper and lower sides of the rotor 180 can be smoothly moved.

Meanwhile, in the present embodiment, the permanent magnet 190 may be formed of a bonded magnet.

The permanent magnet 190 may be formed of, for example, a neodymium-bonded magnet.

The permanent magnet 190 may be integrally formed on the outer surface of the rotor frame 221 by injection.

According to such a configuration, the post-machining operation for machining the permanent magnet 190 to have the minimum outer diameter (dom) at the center of each magnetic pole portion 193 can be eliminated.

As a result, the cost due to the post-processing of the permanent magnet 190 can be reduced, and the amount of material input to the permanent magnet 190 can be reduced.

The rollers 135 may be coupled to the eccentric portion 188 of the rotary shaft 185 and the rollers 135 may be received in the cylinder 131.

The main bearing 137 and the sub bearing 139 are coupled to the upper side and the lower side of the cylinder 131 and the permanent magnet 190 can be coupled to the rotor frame 221.

When the operation is started and power is applied to the stator coil 171, the magnetic field formed by the stator coil 171 and the magnetic field formed by the permanent magnet 190 interact with each other, (Not shown).

At this time, the magnetic flux density formed by the permanent magnet 190 of the rotor 180 has a sinusoidal shape, so that ripples are reduced, vibration and noise due to the ripple are suppressed, and silent operation is possible.

When the rotor 180 is rotated, the roller 135 is rotated in the cylinder 131 around the rotation shaft 185 and the refrigerant sucked into the cylinder 131 through the suction pipe 117 Can be compressed.

The refrigerant compressed and discharged in the cylinder 131 may be discharged to the outside of the case 110 through the discharge tube 119.

FIG. 7 is a sectional view of a rotor of a motor having permanent magnets according to another embodiment of the present invention, FIG. 8 is a plan view of the rotor of FIG. 7, and FIG. 9 is an enlarged view of the permanent magnet of FIG.

The electric motor 150 of this embodiment includes a stator 160; And a rotor 180a rotatably disposed with a gap G with respect to the stator 160. The rotor 180a includes a rotating shaft 185 and a permanent magnet 190a, The permanent magnet 190a is pole-anisotropic so that a magnetic field is formed on the surface facing the gap G. The permanent magnet 190a has a plurality of magnetic pole portions 193 alternately arranged in the circumferential direction, And the permanent magnet 190a may have a profile such that the outer diameter of the outer surface 191 gradually increases from the respective centers of the plurality of magnetic pole portions 193 toward both ends.

The permanent magnet 190a may have a substantially cylindrical shape.

The permanent magnet 190a may include a plurality of magnetic pole portions 193 to alternately form different magnetic poles along the circumferential direction.

The plurality of magnetic pole portions 193 may include four first magnetic pole portions 193a and four second magnetic pole portions 193b as described above.

The permanent magnet 190a may have a minimum outer diameter Domin at the center of each magnetic pole portion 193 and a maximum outer diameter at both ends.

The permanent magnet 190a may be formed such that the difference t2 between the maximum outer diameter Dom and the minimum outer diameter Domin is 20 to 30% of the maximum outer diameter of the permanent magnet 190a.

The magnetic flux density of the gap G is maximized in the boundary region of the magnetic pole portion 193 and minimized at the center of each of the magnetic pole portions 193 so that the graph of the magnetic flux density of the gap G can be expressed as a sinusoidal wave shape .

According to such a configuration, ripples (cogging torque and torque ripple) are reduced, and generation of vibration and noise due to the ripple can be suppressed.

Further, the post-machining of the permanent magnet 190a is eliminated, and the post-machining cost can be reduced.

In addition, the amount of material input to the permanent magnet 190a can be reduced, and the material cost can be reduced.

The rotor 180a may include a rotor frame 221a provided between the rotating shaft 185 and the permanent magnet 190a.

The rotor frame 221a may be implemented as a non-magnetic body made of a lightweight material.

The rotor frame 221a may be formed of, for example, a synthetic resin material.

A rotating shaft hole 223 may be formed at the center of the rotor frame 221a.

The rotor frame 221a may include a plurality of penetration portions 225 which are axially penetrated around the rotation shaft hole 223 and spaced apart in the circumferential direction.

The rotor frame 221a may have an engaging part 230 so as to be engaged with the rotation shaft 185 with respect to the rotation direction.

The engaging portion 230 of the rotor frame 221a may include a protruding portion 231a protruding along the radial direction and a depressed portion 231b recessed along the radial direction, for example.

The projecting portions 231a and the depressed portions 231b may be alternately arranged along the circumferential direction.

The rotor frame 221a may have a reduced length along the axial direction, for example, as compared with the permanent magnet 190a.

The upper end of the rotor frame 221a and the upper end of the permanent magnet 190a may have a predetermined height difference L1.

The lower end of the rotor frame 221a and the lower end of the permanent magnet 190a may have a preset height difference L2.

Here, the top height difference L1 and the bottom height difference L2 may be equal to each other.

Thereby, the mass of the rotor frame 221a can be further reduced.

The permanent magnet 190a may be coupled to the outer surface of the rotor frame 221a.

The rotor frame 221a and the permanent magnet 190a may be integrally joined by an adhesive 240, for example.

The adhesive 240 may be applied to the mutual coupling region of the rotor frame 221a and the permanent magnet 190a.

Meanwhile, the permanent magnets 190a may be configured such that the inner surface 192a has the same diameter.

According to this configuration, the surface magnetic flux density of the permanent magnet 190a can be reduced as compared to the permanent magnet 190 of the embodiment described above with reference to Figs.

FIG. 10 is a graph showing the vacant magnetic flux density of the permanent magnet of FIG. 1, and FIG. 11 is a graph showing the vacant magnet density of the permanent magnet of FIG.

10 and 11, each of the permanent magnets 190 and 190a of the present embodiment has an outer surface 191 having a minimum outer diameter Domin at the center of each magnetic pole portion 193, and each magnetic pole portion 193, (Cogging torque and toothed ripple), respectively, because the graph of the magnetic flux density of the gap G has a sinusoidal (sinusoidal) shape as described above, And the generation of vibration and noise due to the ripple can be reduced.

However, as shown in Fig. 11, the magnetic flux density (torque) of the gap G in the embodiment having the permanent magnet 190a in relation to Fig. 7 is the same as that of the permanent magnet 190 in Fig. The magnitude of the magnetic flux density (torque) of the gap G of the embodiment having the magnetic flux density G is reduced by about 10 to 12%.

Accordingly, the output density of the electric motor in relation to FIG. 7 can be reduced in comparison with the output density of the electric motor 150 relating to FIG.

In order to maintain the same output density as that of the motor 150 of the embodiment of FIG. 1, the size of the permanent magnet 190a of the embodiment of FIG. 7 must be increased, so that the amount of material input to the permanent magnet 190a may be increased , It may be disadvantageous in terms of compactness.

The motor 150 of the embodiment of FIG. 1 can reduce the size of the permanent magnets in the radial direction when the same output level is maintained as compared with the motor of the embodiment described above with reference to FIG. 7, which is more advantageous for compactness.

In addition, when the motor 150 of the embodiment of FIG. 1 maintains the same output level as that of the motor of the embodiment described above with reference to FIG. 7, the input amount of the permanent magnet material can be reduced.

The foregoing has been shown and described with respect to specific embodiments of the invention. However, the present invention may be embodied in various forms without departing from the spirit or essential characteristics thereof, so that the above-described embodiments should not be limited by the details of the detailed description.

Further, even when the embodiments not listed in the detailed description have been described, it should be interpreted broadly within the scope of the technical idea defined in the appended claims. It is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

110: case, 130: compression part, 131: cylinder, 135: roller,
137: main bearing, 139: sub bearing, 150: electric motor, 160: stator,
162: electric steel plate, 163: rotor receiving hole, 165; Slot, 166: pole,
171: stator coil, 180, 180a: rotor, 185; 187: through hole,
188: eccentric portion, 190, 190a: permanent magnet, 193: stimulating portion, 193a: first stimulating portion,
193b: second magnetic pole part, 221, 221a: rotor frame, 223: rotating shaft hole, 225:

Claims (11)

Stator; And a rotor rotatably disposed inside the stator with a gap against the stator,
The rotor may include:
A rotating shaft;
A permanent magnet having a cylindrical shape and disposed concentrically with the rotation axis; And
And a rotor frame connecting the rotating shaft and the permanent magnet,
Wherein the permanent magnet has a magnetic field formed on a surface facing the gap and a pole anisotropic magnet so that a magnetic field is not formed on the surface opposite to the gap,
Wherein the permanent magnet includes a plurality of magnetic pole portions alternately arranged with mutually different magnetic poles along the circumferential direction,
Wherein the permanent magnet has a profile whose outer diameter gradually increases from the center of each of the plurality of magnetic pole portions to both ends thereof,
Wherein the permanent magnet has an outer surface having a minimum outer diameter at each center of the plurality of magnetic pole portions and a maximum outer diameter at both ends of the plurality of magnetic pole portions,
Wherein the permanent magnet has an inner surface having a minimum inner diameter at each center of the plurality of magnetic pole portions and a maximum inner diameter at both ends of the plurality of magnetic pole portions,
Wherein the magnetic flux density of the gap is maximized at both ends of each of the magnetic pole portions and the magnetic flux density of the gap is minimized at the center of each of the magnetic pole portions. The method according to claim 1,
Wherein the permanent magnets have the same thickness and the inner surface is formed to correspond to the shape of the outer surface. The method according to claim 1,
Wherein the permanent magnets are formed such that an inner surface of the permanent magnet increases in a direction from the center of the plurality of magnetic pole portions toward both ends, or is formed to have the same shape as the outer surface. The method of claim 3,
Wherein the thickness of the center of the plurality of magnetic pole portions is 90% to 100% of the thickness of both end portions of the plurality of magnetic pole portions. The method according to claim 1,
Wherein the difference between the maximum outer diameter and the minimum outer diameter of the permanent magnet is 20% to 30% of the thickness of the permanent magnet. The method according to claim 1,
And the outer surface of the rotor frame is formed to have a shape corresponding to the shape of the inner surface of the permanent magnet. The method according to claim 6,
Wherein the rotating shaft and the rotor frame are made of different materials. 8. The method of claim 7,
And the rotor frame is injection-molded around the rotating shaft. The method according to claim 6,
Wherein the permanent magnet is a bonded magnet. The method according to claim 6,
Wherein the rotor frame is formed to have a profile extending along a circumferential direction so as to gradually decrease from a point having a maximum outer diameter to a point having a minimum outer diameter. case;
A compression unit provided inside the case and compressing the fluid; And
And a motor provided inside the case and having a permanent magnet according to any one of claims 1 to 10 for providing a driving force to the compression section.

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