Patent Description:
As is well known, an electric motor is an apparatus that converts electric energy into mechanical energy.

Electric motors are classified into a direct current (DC) type, a single phase alternating current (AC) type, and a three-phase AC type depending on an electric power (or power) supply system.

Such an electric motor generally includes a stator, and a rotor disposed to be movable relative to the stator with a predetermined gap therebetween.

A part of the rotor includes a rotor core having a rotating shaft, a plurality of conductor bars inserted into the rotor core in an axial direction, and an end ring shorting the conductor bars.

Another part of the rotor includes a permanent magnet, and a rotor frame provided with a rotating shaft to support the permanent magnet.

However, in the related art electric motor having the permanent magnet, a magnetic body (a back yoke) is provided at the rear of the permanent magnet to form a flux path, which causes an increase in a mass of the rotor.

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

Further, when the mass of the rotor is increased, the inertia of the rotor is increased, which may make it difficult to start and stop the rotor.

In addition, the magnetic body is formed of a high-priced magnetic steel sheet (or electromagnetic steel sheet or silicon steel sheet) having a high magnetic property, which may cause an increase in manufacturing costs.

On the other hand, a compressor includes a case, a compression unit provided inside the case to compress a refrigerant, and an electric motor provided inside the case to supply driving force to the compression unit.

The compression unit includes a cylinder, and a roller provided inside the cylinder and connected to the rotating shaft of the electric motor to be rollable.

The electric motor includes a stator fixed to the inside of the case, and a rotor rotatably disposed in the stator around the rotational shaft.

Bearings are provided on both sides of the cylinder along the axial direction of the cylinder so as to rotatably support the rotating shaft protruding to the both sides of the cylinder.

However, in the related art compressor, the rotor is provided with a rotor core made of a magnetic material and a permanent magnet coupled to the rotor core. This causes an increase in the mass of the rotor which results in increasing vibration and noise.

Particularly, since one side of the rotor is supported by the bearings extending along the axial direction of the rotating shaft, abrasion of the bearings is greatly increased when the mass and the vibration are increased.

<CIT> presents a rotor of permanent magnet motor for compressor, method for manufacturing rotor of permanent magnet motor for the compressor, compressor, and refrigeration cycle. A pole-anisotropic ring magnet is placed in a rotor and a rotary shaft and the pole-anisotropic ring magnet are integrally molded using resin.

<CIT> presents a rotor unit for a brushless direct current motor (BLDC motor) comprises a main body integrally formed with a rotor shaft and an annular ring magnet mounted on the main body. The annular magnet comprises an anisotropic hard ferrite and is laterally magnetized. The rotary shaft and the main body of the rotor unit may be formed from one plastic material. The rotor unit is supported within the BLDC motor via self-lubricating bearing seats.

<CIT> relates to a rotor of a brushless direct-current (brushless direct current) motor, comprising: a polar anisotropic permanent magnet for allowing a magnetized magnetic path to run therethrough; a high-strength core portion mounted on the inner side of the polar anisotropic permanent magnet; and a sound-absorbing resin portion mounted on the inner side of the high-strength core portion.

<CIT> discloses an electric induction motor rotor which comprises a ring of ceramic magnetic or magnetisable material, carried by a rotor shaft at a hub which has been injection moulded into position between the ring and shaft. <CIT> presents an impeller that has a shaft portion that is mounted on a hollow shaft. A plate portion is arranged in radial at the hollow shaft. The shaft portion is adjoined with a bearing region. The permanent magnets are arranged outside the hollow shaft. The blind holes are formed in the hollow shaft. The accessories are installed in the blind holes. The control magnet is formed with respect
to the permanent magnets.

<CIT> presents a hermetic electric compressor comprising: a motor rotor having a permanent magnet arranged on an outer circumference thereof; a motor rotor fixed to the crankshaft; and a motor stator facing the rotor fixed to a sealed case.

<CIT> presents a hermetic compressor in which a rotor is fixed to a rotor fixing portion of a crankshaft via a non-magnetic sleeve formed of a non-magnetic material.

<CIT> presents a fluid machine in which oil supply grooves are formed respectively in a rotating shaft of a compression mechanism integral with an electric motor and in a rotating shaft of an expansion mechanism. The rotating shafts are coupled together by engagement between an engagement convex portion and an engagement concave portion which are formed respectively in shaft ends of the rotating shafts. And, a seal groove is formed in the peripheral surface of the engagement convex portion and an O-ring is engaged into the seal groove.

Therefore, the present invention is directed to providing an electric motor having a permanent magnet capable of reducing mass of a rotor and suppressing vibration and noise occurrence and/or a compressor including the same.

In addition, the present invention is directed to providing an electric motor having a permanent magnet capable of easily changing a material, a shape and a size of a rotor frame supporting the permanent magnet and/or a compressor including the same.

Further, the present invention is directed to providing an electric motor having a permanent magnet capable of reducing mass of a rotor and easily manufacturing a rotor and/or a compressor including the same.

Furthermore, the present invention is directed to providing an electric motor having a permanent magnet capable of suppressing vibration of a rotor to reduce wear of a bearing.

In order to achieve the objects as described above, the present invention provides a compressor as defined in claim <NUM>.

Accordingly, since the permanent magnet support means does not have to form a flux path, the design of the permanent magnet support means may be free.

According to the present invention, the permanent magnet support means includes a rotor frame provided between the rotating shaft and the permanent magnet, wherein the permanent magnet has a cylindrical shape, and the rotor frame does not form a flux path of the permanent magnet, and is formed so as to connect the rotating shaft and the permanent magnet.

According to the present invention, the rotating shaft and the rotor frame are configured to be formed of the same material.

According to the present invention, the rotating shaft and the rotor frame are formed of the same material, and the rotor frame is formed integrally so as to protrude from the outer surface of the rotating shaft along the radial direction.

According to the present invention, the rotor frame includes a hub provided with the rotating shaft therein, a cylindrical part disposed concentrically with the hub at an outer side of the hub, and a connecting part connecting the hub and the cylindrical part.

According to one embodiment of the present invention, the permanent magnet is a sintered magnet, and an adhesive layer is provided between the permanent magnet and the rotor frame.

According to the present invention, the rotor frame is formed to have a reduced length as compared with the permanent magnet along the axial direction.

According to one embodiment of the present invention, the permanent magnet is a bonded magnet, and the permanent magnet is configured to be injection-molded at an outer surface of the rotor frame.

According to one embodiment of the present invention, the compression unit includes: a cylinder forming a compression space; a roller connected to a rotating shaft of the electric motor having the permanent magnet and rotated inside the cylinder; and a bearing provided at the cylinder to rotatably support the rotating shaft.

According to one embodiment of the present invention, the rotating shaft includes a first shaft portion coupled to a rotor frame and a second shaft portion coupled to the roller, wherein the first shaft portion and the second shaft portion are configured to be coupled integrally to each other after the rotor frame and the roller are coupled.

As described above, according to the present invention, a permanent magnet is magnetized in polar anisotropy such that a magnetic field is formed on a surface of the permanent magnet facing a gap and a magnetic field is not formed on a surface of the permanent magnet opposite to the gap, and a permanent magnet support means (rotor frame) does not form a flux path of the permanent magnet and is formed to connect the rotating shaft and the permanent magnet, and thus mass of a rotor may be reduced, and vibration and noise occurrence of the rotor may be suppressed.

Further, since the rotor frame supporting the permanent magnet may be formed independently of the formation of the flux path of the permanent magnet, a material, a shape, and a size of the rotor frame may be changed easily.

Accordingly, not only the mass of the rotor may be reduced but also the rotor may be manufactured easily.

Further, since the rotor frame does not form the flux path, it may be formed integrally with the rotating shaft with the same material as that of the rotating shaft, thereby easily manufacturing the rotor.

Furthermore, since the rotor frame does not form the flux path, the rotor frame is formed with a plastic which is a non-magnetic material and has a small gravity, thereby reducing the mass of the rotor.

Furthermore, the mass of the rotor is reduced and the generation of vibration is suppressed, and thus a compression unit is connected to one end portion of the rotating shaft of the rotor, and wear of a bearing provided between the rotor and the compression unit may be reduced remarkably.

In addition, since the rotor frame is formed to be shortened in an axial direction as compared with the permanent magnet, and a bearing insert portion for inserting the bearing inside the rotor is not formed separately, thereby easily manufacturing the rotor.

Hereinafter, embodiments disclosed in this specification will be described in detail with reference to the accompanying drawings. In this specification, the same or equivalent components may be provided with the same or similar reference numbers even in different embodiments, and description thereof will not be repeated. In describing the present invention, if a detailed explanation for a related known technology or construction is considered to unnecessarily divert the gist of the present disclosure, such explanation has been omitted but would be understood by those skilled in the art. It should be noted that the attached drawings are provided to facilitate understanding of the embodiments disclosed in this specification, and should not be construed as limiting the technical idea disclosed in this specification by the attached drawings.

<FIG> is a cross-sectional view of a compressor provided with an electric motor having a permanent magnet, <FIG> is an enlarged view of the rotor of <FIG>, and <FIG> is a view for describing magnetization of the permanent magnet of <FIG>.

As shown in <FIG> and <FIG>, a compressor provided with an electric motor having a permanent magnet includes: a case <NUM>; a compression unit <NUM> provided inside the case <NUM> to compress refrigerant; and an electric motor <NUM> provided in the case <NUM> to supply a driving force to the compression unit <NUM> and having the permanent magnet.

For example, the case <NUM> may be configured to have a closed space therein.

For example, the case <NUM> may include a cylindrical-shaped body <NUM> and a first cap <NUM> and a second cap <NUM> provided at both end portions (upper and lower portions in drawings) of the body <NUM>, respectively.

An intake tube <NUM> may be provided at one side (side portion of the body <NUM> in drawings) of the case <NUM>.

The intake tube <NUM> may communicate with the compression unit <NUM>.

Accordingly, the refrigerant may be intaken into the compression unit <NUM>.

A discharge tube <NUM> may be provided at the other side of the case <NUM> (the first cap <NUM> in drawings).

Accordingly, the compressed refrigerant may be discharged outward from the case <NUM>.

For example, the compression unit <NUM> may be provided at a lower region inside the case <NUM>.

For example, the compression unit <NUM> may include a cylinder <NUM> in which a compression space is formed, a roller <NUM> rotated inside the cylinder <NUM>, and a main bearing <NUM> (upper bearing) and a sub bearing <NUM> (lower bearing) provided at both sides (upper and lower sides in drawings) of the cylinder <NUM>,.

For example, the main bearing <NUM> may block an upper side of the cylinder <NUM>.

The main bearing <NUM> may be expanded relative to the cylinder <NUM> to be supported fixedly inside the case <NUM>.

For example, the sub bearing <NUM> may be formed so as to block a lower side of the cylinder <NUM>.

Bearing surfaces may be provided inside the main bearing <NUM> and the sub bearing <NUM> so as to rotatably support the rotating shaft <NUM>, respectively.

Meanwhile, an electric motor <NUM> (hereinafter referred to as an electric motor <NUM>) having a permanent magnet for providing a driving force to the compression unit <NUM> is provided inside the case <NUM>.

The electric motor <NUM> includes: a stator <NUM>; and a rotor <NUM> rotatably disposed about the rotating shaft <NUM> with a gap G from the stator <NUM>.

The stator <NUM> may include a rotor accommodating hole <NUM> in which the rotor <NUM> is accommodated.

The stator <NUM> may include a stator core <NUM> and a stator coil <NUM> wound around the stator core <NUM>.

The stator core <NUM> may be formed by insulating and stacking a plurality of electric steel plates <NUM> having the rotor accommodating hole <NUM> at a center thereof.

The stator core <NUM> may include a plurality of slots <NUM> and teeth <NUM> formed around the rotor accommodating holes <NUM>.

The rotor <NUM> includes: a rotating shaft <NUM>; a permanent magnet <NUM> disposed concentrically with the rotating shaft <NUM>; and a rotor frame <NUM> for supporting the permanent magnet <NUM>.

The rotating shaft <NUM> may be configured to have a long length to be connected to the rotor frame <NUM> at one side thereof and to be connected to the roller <NUM> at the other side thereof.

A through hole <NUM> passing through along an axial direction may be formed inside the rotating shaft <NUM>.

An eccentric part <NUM> may be formed at a region to which the roller <NUM> is coupled.

The roller <NUM> may move eccentrically about the rotating shaft <NUM> inside the cylinder <NUM>.

Accordingly, the refrigerant intaken into the cylinder <NUM> may be compressed by the eccentric rotational movement of the roller <NUM>.

The permanent magnet <NUM> is configured in a cylindrical shape.

Meanwhile, as shown in <FIG>, the permanent magnet <NUM> is magnetized in polar anisotropy such that a magnetic field is formed on a surface 192a (an outer surface 192a in drawings) facing the gap G and a magnetic field is not formed on a surface 192b (an inner surface 192a in drawings) opposite to the gap G.

Accordingly, a magnetic field is formed at an outer side of the permanent magnet <NUM>, and a magnetic field is not formed at an inner side of the permanent magnet <NUM>.

The permanent magnet <NUM> may include a plurality of magnetic pole portions <NUM> at which different poles (N poles, S poles) are disposed alternately along a circumferential direction.

According to such as configuration, in that the rotor frame <NUM> provided at the inner side of the permanent magnet <NUM> does not form a flux path of the permanent magnet <NUM>, since restriction on a material, a shape, and a size of the rotor frame <NUM> is small, the rotor frame <NUM> may be formed more freely.

Accordingly, the rotor frame <NUM> may be manufactured easily.

The rotor frame <NUM> is configured to have a shortened length as compared with the permanent magnet <NUM> in the axial direction.

Accordingly, the mass of the rotor frame <NUM> may be reduced.

For example, the rotor frame <NUM> may be formed to be reduced from both end portions to the inner side of the permanent magnet <NUM>, respectively.

Accordingly, since an empty space is formed between the permanent magnet <NUM> and the rotor frame <NUM> without any additional processing, the end portion of the main bearing <NUM> (upper end portion in drawings) may be inserted easily.

Accordingly, unlike the related art in which a bearing insert portion is formed at the rotor frame, since the bearing insert portion is not formed, the rotor <NUM> may be manufactured easily.

<FIG> is a plan view of the rotor of <FIG>, and <FIG> is a view illustrating a state before the permanent magnet and the rotor frame of the rotor of <FIG> are coupled.

As shown in <FIG>, the rotor frame <NUM> includes a hub <NUM> having the rotating shaft <NUM> therein, a cylindrical part <NUM> disposed concentrically with the hub <NUM> at an outer side of the hub <NUM>, and a connecting part <NUM> connecting the hub <NUM> and the cylindrical part <NUM>.

According to the invention, the rotor frame <NUM> is formed of the same material as that of the rotating shaft <NUM>.

In a comparative example not belonging to the invention, the rotor frame <NUM> and the rotating shaft <NUM> may be manufactured separately from each other to be integrally coupled to each other.

According to the invention, the rotor frame <NUM> and the rotating shaft <NUM> are simultaneously manufactured integrally by casting.

For example, the hub <NUM> may protrude from an outer diameter surface of the rotating shaft <NUM> by a predetermined thickness, and may be extended to have a predetermined length in the axial direction.

Referring to <FIG>, a case in which the hub <NUM>, the connecting part <NUM>, and the cylindrical part <NUM> are realized to have the same length in the axial direction is illustrated, but this is merely an example, not belonging to the invention, and the hub <NUM>, the connecting part <NUM>, and the cylindrical part <NUM> are configured according to the invention to have different lengths in the axial direction.

According to the invention, the length in the axial direction of the connecting part <NUM> or the hub <NUM> is formed to be smaller than that of the cylindrical part <NUM>.

For example, the connecting part <NUM> may be formed to protrude from an outer surface of the hub <NUM> in a radial direction to be connected to an inner surface of the cylindrical part <NUM>.

For example, the connecting part <NUM> may include spokes <NUM> having a predetermined width along the circumferential direction to be spaced apart from each other at a predetermined distance along the circumferential direction.

For example, the connecting part <NUM> may include a penetration portion <NUM> formed between the spokes <NUM>.

For example, the penetration portion <NUM> may have a fan shape.

Here, for example, the penetration portion <NUM> may be formed in a circular shape, an elliptical shape, and other polygonal shapes.

Meanwhile, for example, the permanent magnet <NUM> may be realized as a sintered magnet formed by sintering.

The permanent magnet <NUM> realized as the sintered magnet may be bonded to the rotor frame <NUM> by an adhesive <NUM>.

For example, the permanent magnet <NUM> and the rotor frame <NUM> may be inserted and coupled in the axial direction as shown in <FIG>.

The adhesive <NUM> may be provided at mutual contact surfaces of the permanent magnet <NUM> and the rotor frame <NUM>.

According to such a configuration, the rotating shaft <NUM>, the rotor frame <NUM>, and the permanent magnet <NUM> may be formed respectively, and the roller <NUM> may be coupled to the eccentric part <NUM> of the rotating shaft <NUM> of the rotor <NUM>.

The roller <NUM> may be coupled to the inside of the cylinder <NUM> and the main bearing <NUM> and the sub bearing <NUM> may be coupled to the upper side and the lower side of the cylinder <NUM> respectively.

The adhesive <NUM> may be applied to at least one surface of the mutual contact surfaces of the rotor frame <NUM> and the permanent magnet <NUM>, and the permanent magnet <NUM> and the rotor frame <NUM> may be inserted and coupled in the axial direction.

The rotor frame <NUM> may be disposed at an upper end of the rotating shaft <NUM>, and the rotor frame <NUM> and the rotating shaft <NUM> may be moved relative to each other in the axial direction to couple to the rotor frame <NUM> and the rotating shaft <NUM>.

At this point, the rotor frame <NUM> includes a shortened length as compared with the permanent magnet <NUM> in the axial direction, so that one region of an upper end of the main bearing <NUM> may be inserted into an empty space between the permanent magnet <NUM> and the rotor frame <NUM>.

Meanwhile, when operation is started and power is applied to the stator <NUM>, the rotor <NUM> may be rotated around the rotating shaft <NUM>.

At this point, the rotor <NUM> may be formed to reduce the mass of the rotor frame <NUM> to suppress occurrence of vibration and noise.

In addition, the occurrence of vibration of the rotor <NUM> may be reduced, and wear of the main bearing <NUM> may be suppressed remarkably.

Hereinafter, another compressor will be described with reference to <FIG>.

<FIG> is a cross-sectional view of a compressor provided with an electric motor having a permanent magnet according to another embodiment of the present invention, <FIG> is an enlarged view of the rotor of <FIG>, and <FIG> is a view for describing magnetization of the permanent magnet of <FIG>.

As shown in <FIG> and <FIG>, the compressor provided with the electric motor having the permanent magnet includes: a case <NUM>; a compression unit <NUM> installed in the case <NUM> to compress refrigerant; and an electric motor 150a provided in the case <NUM> to provide a driving force to the compression unit <NUM> and having the permanent magnet.

The case <NUM> may include a body <NUM>, and a first cap <NUM> and a second cap <NUM> provided at both end portions of the body <NUM>.

An intake tube <NUM> and a discharge tube <NUM> may be provided at the case <NUM>, respectively.

The compression unit <NUM> may include a cylinder <NUM>, a roller <NUM> provided in the cylinder <NUM>, a main bearing <NUM> and a sub bearing <NUM> provided at both sides of the cylinder <NUM>.

Meanwhile, the electric motor 150a (hereinafter referred to as 'electric motor 150a') having the permanent magnet includes: a stator <NUM>; and a rotor 180a rotatably disposed with a predetermined gap G with respect to the stator <NUM>, and the rotor 180a includes: a rotating shaft 185a; a permanent magnet <NUM> disposed concentrically with the rotating shaft 185a; and a rotor frame 201a provided between the rotating shaft 185a and the permanent magnet <NUM>.

For example, the stator <NUM> may include a stator core <NUM> and a stator coil <NUM> wound around the stator core <NUM>.

The stator core <NUM> may be formed, for example, by insulating and stacking a plurality of electric steel plates <NUM> having a rotor accommodating hole <NUM> therein.

A plurality of slots <NUM> and teeth <NUM> may be provided around the rotor accommodating hole <NUM>.

The rotor 180a includes a rotating shaft 185a, a permanent magnet <NUM>, and a rotor frame 201a.

Meanwhile, for example, the rotating shaft 185a may include a first shaft portion <NUM> and a second shaft portion <NUM> which are coupled to each other in the axial direction.

The rotor frame 201a may be coupled to the first shaft portion <NUM>.

The roller <NUM> may be coupled to the second shaft portion <NUM>.

Accordingly, the rotating shaft 185a and the rotor frame 201a may be coupled to each other easily, and the rotating shaft 185a and the roller <NUM> may be coupled to each other easily.

For example, the first shaft portion <NUM> and the second shaft portion <NUM> may be configured to have a concave-convex portion <NUM> which is movable in the axial direction and engaged to be restricted in the rotation direction.

For example, the concave-convex portion <NUM> may include a protrusion 189a protruding from the first shaft portion <NUM> and the second shaft portion <NUM> in the axial direction, respectively, and a protrusion groove 189b recessed to accommodate the protrusion 189a.

The rotating shaft 185a may include a through hole <NUM> penetrating therein in the axial direction.

The permanent magnet <NUM> has a cylindrical shape.

As shown in <FIG>, the permanent magnet <NUM> is magnetized in polar anisotropy such that a magnetic field is formed on a surface 192a (an outer surface in drawings) facing the gap G and is not formed on a surface 192b (an inner surface in drawings) opposite to the gap.

Accordingly, since a magnetic field is formed at an outer side of the permanent magnet <NUM>, a magnetic field is not formed at an inner side of the permanent magnet <NUM>, and the rotor frame 201a disposed at the inner side of the permanent magnet <NUM> is not constrained to the magnetic field, formation (manufacturing) thereof may be made more freely.

The permanent magnet <NUM> may be provided with a plurality of magnetic pole portions <NUM> at which different poles (N poles, S poles) are disposed alternately along a circumferential direction.

<FIG> is a plan view of the rotor of <FIG>, <FIG> is a perspective view of a main part of the rotating shaft of <FIG>, and <FIG> is a plan view of the rotor frame of <FIG>,.

As shown in <FIG>, the rotor frame 201a includes a hub <NUM> having the rotating shaft 185a therein, a cylindrical part <NUM> disposed concentrically with the hub <NUM> at an outer side of the hub <NUM>, and a connecting part <NUM> connecting the hub <NUM> and the cylindrical part <NUM>.

For example, the rotor frame 201a may be formed of a non-magnetic member of a lightweight material.

In more detail, for example, the rotor frame 201a may be formed of a synthetic resin member (plastic).

For example, the connecting part <NUM> may include a plurality of spokes <NUM> connecting the hub <NUM> and the cylindrical part <NUM> and a penetration portion <NUM> formed to pass through between the spokes <NUM>.

For example, as shown in <FIG>, the rotating shaft 185a may include a protrusion <NUM> protruding at an outer surface in the radial direction.

The protrusion <NUM> may be formed to be spaced apart from each other along the circumferential direction of the rotating shaft 185a.

The protrusion <NUM> may be disposed to be spaced apart from each other along the axial direction of the rotating shaft 185a.

The protrusion <NUM> may be formed to be spaced apart to correspond to both end portions of the rotor frame 201a.

In an example not belonging to the invention, the rotor frame 201a may be formed by injection molding around the rotating shaft 185a.

In an example not belonging to the invention, as shown in <FIG>, the rotor frame 201a may be provided with an engaging portion <NUM> engaging with the protrusion <NUM> in the rotation direction (circumferential direction).

For example, the engaging portion <NUM> may include a protrusion portion inserted between the protrusions <NUM>, and a groove portion into which the protrusion <NUM> is inserted.

According to the invention, the rotor frame 201a is configured to have a shortened (reduced) length in the axial direction compared with that of the permanent magnet <NUM>.

Accordingly, the mass of the rotor frame 201a may be reduced remarkably.

Accordingly, the mass of the rotor 180a may be reduced, and occurrence of vibration and noise due to vibration may be reduced.

<FIG> illustrates a modified example of the rotating shaft of <FIG>, and <FIG> is a plan view of a modified example of the rotor frame of <FIG>,.

As shown in <FIG>, the rotating shaft 185a may be configured to have a groove <NUM> recessed inwardly along the radial direction.

The grooves <NUM> may be formed to be spaced apart from each other along the circumferential direction of the rotating shaft 185a.

The grooves <NUM> may be formed to be spaced apart from each other along the axial direction of the rotating shaft 185a.

In a comparative example not belonging to the invention, as shown in <FIG>, the rotor frame 201a may be provided with an engaging portion 195a engaging with the groove <NUM> along the rotation direction.

For example, the engaging portion 195a may be configured to have an insert portion <NUM> inserted into the groove <NUM> and a contact portion <NUM> contacting an outer surface of the rotating shaft 185a.

For example, the permanent magnet <NUM> may be composed of a sintered magnet formed by sintering by pressurizing and heating magnetic substance powder.

The permanent magnet <NUM> may be bonded to an outer surface of the rotor frame 201a by an adhesive <NUM>.

Meanwhile, for example, the permanent magnet <NUM> may be composed of a bonded magnet obtained by solidifying the magnetic substance powder with a synthetic resin (plastic).

In a comparative example not belonging to the invention, as shown in <FIG>, the permanent magnet 191a may be configured to have a length Lm in the axial direction equal to a length Lr in the axial direction of the rotor frame 201a.

After the rotating shaft 185a and the rotor frame 201a are injection-molded, the permanent magnet 191a may be manufactured by injection molding at the outer surface of the rotor frame 201a.

According to such a configuration, the rotor frame 201a may be formed integrally around the protrusion <NUM> of the rotating shaft 185a (the first shaft portion <NUM>) by injection.

The permanent magnet <NUM> may be coupled integrally to the outer surface of the rotor frame 201a by the adhesive <NUM>, or the permanent magnet <NUM> may be formed integrally by injection.

The roller <NUM> may be coupled around the rotating shaft 185a (the second shaft portion <NUM>).

The main bearing <NUM> and the sub bearing <NUM> may be coupled to the rotating shaft 185a (the second shaft portion <NUM>).

The first shaft portion <NUM> provided with the rotor frame 201a and the second shaft portion <NUM> coupled to the roller <NUM> and the main bearing <NUM> may be coupled integrally to each other so that the concave-convex portion <NUM> is engaged along the axial direction.

The concave-convex portion <NUM> may be integrally coupled to each other by welding or bonding.

Meanwhile, when the operation is started and power is applied to the stator coil <NUM>, the rotor 180a may be rotated about the rotating shaft 185a.

At this point, since the rotor 180aincludes the rotor frame 201a of a lightweight material, the total mass is reduced, thereby suppressing the generation of vibration and noise.

The rotor frame 201a and the rotating shaft 185a may be prevented from slipping in the rotation direction by the protrusion <NUM> and the engaging portion <NUM>.

In the embodiments related to <FIG>, a case in which the electric motor having the permanent magnet is configured to drive the compression unit is illustrated, but it goes without saying that the electric motor having the permanent magnet may be configured as an electric motor having a separate motor case.

Claim 1:
A compressor comprising:
- a case (<NUM>);
- a compression unit (<NUM>) provided inside the case (<NUM>) to compress fluid; and
- an electric motor (<NUM>, 150a) provided inside the case (<NUM>) to provide driving force to the compression unit (<NUM>),
wherein the electric motor (<NUM>, 150a) comprises:
a stator (<NUM>); and
a rotor (<NUM>, 180a) rotatably disposed and spaced a predetermined gap (G) apart from the stator (<NUM>),
wherein the rotor (<NUM>, 180a) includes:
a rotating shaft (<NUM>, 185a);
a permanent magnet (<NUM>, 191a) disposed concentrically with the rotating shaft (<NUM>, 185a); and
a rotor frame (<NUM>, 201a) provided between the rotating shaft (<NUM>, 185a) and the permanent magnet (<NUM>, 191a);
wherein the permanent magnet (<NUM>, 191a) has a cylindrical shape and is magnetized in polar anisotropy such that a magnetic field is formed on a surface of the permanent magnet (<NUM>, 191a) facing the gap (G) and a magnetic field is not formed on a surface of the permanent magnet (<NUM>, 191a) opposite to the gap (G), and
the rotor frame (<NUM>, 201a) does not form a flux path of the permanent magnet (<NUM>, 191a) and is formed so as to connect the rotating shaft (<NUM>, 185a) and the permanent magnet (<NUM>, 191a); and
wherein the rotor frame (<NUM>) is formed integrally so as to protrude from an outer surface of the rotating shaft (<NUM>) along a radial direction,
characterized in that:
the rotating shaft (<NUM>) and the rotor frame (<NUM>) are formed of the same material,
the rotor frame (<NUM>) and the rotating shaft (<NUM>) are manufactured integrally by casting,
the rotor frame (<NUM>, 201a) includes a hub (<NUM>) provided with the rotating shaft (<NUM>, 185a) therein, a cylindrical part (<NUM>) disposed concentrically with the hub (<NUM>) at an outer side of the hub (<NUM>), and a connecting part (<NUM>) connecting the hub (<NUM>) and the cylindrical part (<NUM>),
the rotor frame (<NUM>) is configured to have a length shorter than a length of the permanent magnet (<NUM>) in an axial direction, and
a length of the connecting part (<NUM>) or the hub (<NUM>) in the axial direction is shorter than a length of the cylindrical part (<NUM>) in the axial direction.