Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K1/00—Details of the magnetic circuit
  • H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
  • H02K1/22—Rotating parts of the magnetic circuit
  • H02K1/27—Rotor cores with permanent magnets
  • H02K1/2706—Inner rotors
  • H02K1/272—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis
  • H02K1/274—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets
  • H02K1/2753—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets the rotor consisting of magnets or groups of magnets arranged with alternating polarity
  • H02K1/278—Surface mounted magnets; Inset magnets
  • H02K1/2781—Magnets shaped to vary the mechanical air gap between the magnets and the stator
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K7/00—Arrangements for handling mechanical energy structurally associated with dynamo-electric machines, e.g. structural association with mechanical driving motors or auxiliary dynamo-electric machines
  • H02K7/14—Structural association with mechanical loads, e.g. with hand-held machine tools or fans
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K5/00—Casings; Enclosures; Supports
  • H02K5/04—Casings or enclosures characterised by the shape, form or construction thereof
  • H02K5/12—Casings or enclosures characterised by the shape, form or construction thereof specially adapted for operating in liquid or gas
  • H02K5/128—Casings or enclosures characterised by the shape, form or construction thereof specially adapted for operating in liquid or gas using air-gap sleeves or air-gap discs

Definitions

• the present invention relates to a rotor suitable for use in a permanent magnet synchronous electric motor driving a hermetic compressor.
• the permanent magnet synchronous electric motors used in hermetic compressors consist of a stator, and a rotor rotating in the stator.
• the rotor comprises a cylindrical core comprising of ferromagnetic laminations arranged on top of each other and attached to each other by interlock tabs, in which full-length magnet seats are disposed, and magnets placed in the magnet seats, whose transversal section is shaped as an arc segment in some applications.
• the magnets are fixed in the core in axial direction by means of upper and lower rotor covers.
• the rotor cases are fixed by rivets to the core.
• the magnets In order to obtain a desired performance of the electric motor, the magnets should be placed in the core so as to be close to the cylindrical outer surface, and a rather small distance is left between the magnet seats and the outer surface of the core.
• a shaft through-hole is made in axial direction through the center of the core, enabling the core to be attached to a shaft, and rivet through-holes are made in axial direction around the shaft hole. Said holes, the magnet seats and the fine portions in the rotor stack cause temporary springing and deformations in the rotor rotating in high speeds in the stator.
• a narrow air gap is provided between the stator and the rotor.
• the dimensions of the air gap between the rotor and the stator should be circumferentially constant (homogeneous).
• the springing in radial direction of the rotor in high speeds lead to deterioration of the air gap dimensions and friction of the rotor with the stator, decreasing the performance of the electric motor and leading to a loud operation and causing heating problems.
• the patent application no. WO2011108733 (A1) relates to production method of a rotor with surface mounted magnet, on which a cylindrical rotor case is mounted.
• depressed portions are formed circumferentially on the cylindrical rotor case.
• the cylindrical rotor case has an even outer surface, the air gap between the rotor and the stator is homogeneous, and the circumferential movement of the magnets is inhibited by means of separator extensions which are part of the core, extending in radial direction from the core.
• the patent application no. WO2017119102 (A1) relates to an electric motor comprising permanent magnets embedded in a rotor.
• the aim of the present invention is to realize a permanent magnet rotor suitable for use in an electric motor driving a hermetic compressor, with improved resistance against centrifugal forces in high speeds, enabling high torques and silent operation.
• the rotor realized to achieve the aim of the present invention and disclosed in the first claim and the dependent claims, is of the surface mounted magnet type and comprises a ferromagnetic core, and an air gap is provided between the rotor and a stator, substantially effecting performance.
• the rotor of the invention comprises magnets placed circumferentially on the core with equal space in between, shaped as an arc segment curved in radial direction from the circumference of the core towards its center, having a convex lower surface resting on the core and a concave upper surface not contacting the core or any one of the ferromagnetic components.
• the magnets rest on the concave support surfaces around the core.
• the core and the magnets are mounted by being press fitted into a cylindrical rotor case. Since the circumference of the core is spacedly cut-out for the magnets, gaps are disposed between the upper surfaces of the magnets and the rotor case.
• the rotor comprises separator extensions disposed in between the support surfaces of the core, extending in radial direction from the core and outwards from in between the adjacent magnets, abutting on the inner surface of the rotor case, and enabling leaving in circumferential direction a predetermined gap between the magnets and inhibiting the magnets from contacting each other and preventing the circumferential movement of the magnets.
• Figure 1 is a cross sectional view of a hermetic compressor and the electric motor driving the hermetic compressor.
• Figure 2 is an exploded view of the rotor in an embodiment of the invention.
• Figure 3 is a perspective view of a core and magnets placed in a rotor case.
• Figure 4 is a cross sectional view of the rotor in axial direction.
• Figure 5 is an exploded cross sectional view of the rotor core and magnets.
• Figure 6 is a partial cross sectional view of an electric motor comprising a stator with the rotor of the invention.
• Figure 7 is an exploded view of the rotor in another embodiment of the invention.
• a surface mounted magnet type rotor (1) suitable for use in a permanent magnet synchronous electric motor (19) of a hermetic compressor (20), rotating in a stator (15) about a rotary axis (E) formed by a shaft (17) mounted in a shaft hole (16) in its center, having an air gap (18) in between itself and the inner surface of the stator (15), comprises a core (2), also called a rotor stack, made of ferromagnetic laminations or ferromagnetic metal powders ( Figure 1).
• the rotor (1) of the invention comprises
• cylindrical rotor case (7) made of ferromagnetic metal material, in which the core (2) and the magnets (3) are placed by being press fitted, or mounted by being press fitted on the core (2) and the magnets (3), and
• the rotor (1) further comprises a plurality of separator extensions (8) disposed in between the support surfaces (6) around the core (2), extending outwards in radial direction from in between the adjacent magnets (3), abutting to the inner surface of the rotor case (7), enabling leaving a predetermined gap in circumferential direction between the magnets (3), and inhibiting the magnets (3) from contacting each other and preventing the circumferential movement of the magnets (3) ( Figures 2, 5, and 6).
• the rotor case (7) comprises a cylindrical side wall (10) of even structure, a circular bottom wall (11) covering an end of the side wall (10), produced by way of deep drawing method preferably integrally with the side wall (10) or separately from the side wall (10) and joined later, and an opening (12) disposed at the other end of the side wall (10), enabling the core (2) and the magnets (3) to be placed into the rotor case (7) ( Figures 2 and 3).
• the rotor case (7) further comprises a circular upper cover (13) covered on the opening (12) after the core (2) and the magnets (3) are placed therein, and mounted circumferentially to the inner surface of the side wall (10) by being press fitted.
• the bottom wall (11) and the upper cover (13) inhibit the relative movement in axial direction of the core (2) and the magnets (3) inside the rotor case (7) ( Figures 2, 3, 4, and 7)
• the homogeneity of the air gap between the stator (15) and the rotor (1) is provided thanks to the outer surface of the cylindrical side wall being of “even” structure, decreasing the noise level of the electric motor (19) and enhancing its performance, contrary to the uneven structure of the state of the art disclosed in the document no. WO2011108733.
• the rotor case (7) comprises at least one retainer (14) provided on the inner surface of the bottom wall (11) and/or the upper cover (13), abutting on the separator extensions (8), preventing the core (2) from making rotary motion relatively inside the rotor case (7), and enabling substantial entirety of the rotor case (7), core (2) and the magnets (3) ( Figure 2).
• the retainer (14) is shaped as an indentation opening to the inner surface of the bottom wall (11) and/or the upper cover (13), in which the separator extension (8) fits.
• the retainer (14) is shaped as a double protrusion abutting on both sides of the separator extension (8), extending from the inner surface of the bottom wall (11) and/or the upper cover (13) towards the interior of the rotor case (7).
• the rotor case (7) comprises an upper cover (13) and a bottom wall (11) fixed to each other by means of rivets (21) passed through the gaps (9) in axial direction.
• the rivets (21) are passed through the gaps (9) in the rotor (1), fixing the bottom wall (11) and the upper cover (13). This makes it unnecessary to make on the core (2) rivet (21) holes which decrease flux density ( Figure 7).
• the ferromagnetic material loss on the core (2) due to concave support surfaces (6), are compensated by surface mounted magnets (3), achieving a higher flux density and a higher performance with the same rotor (1) volume.
• the skidding of the magnets (3) in radial direction due to the centrifugal force, is prevented by the rotor case (7) circumferentially surrounding the core (2) and the magnets (3). Since the upper surfaces (5) of the magnets (3) facing the rotor case (7) are of concave structure and there are gaps (9) in between, each one of the magnets (3) apply pressure due to centrifugal force to the rotor case (7) only from two points (from their end portions) and in a balanced manner.
• the rotor case (7) does not become deformed, the circularity of the side wall (10) does not deteriorate, thereby maintaining circumferentially equal dimensions of the air gaps (18).
• the gaps (9) inside the rotor (1) allow the upper cover (11) and the bottom wall (11) to be fixed to the core (2) by means of rivets (21) without making holes.

Landscapes

• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Iron Core Of Rotating Electric Machines (AREA)
• Permanent Field Magnets Of Synchronous Machinery (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=63722410

Family Applications (1)

Country Status (3)

Family Cites Families (14)

• 2017
  • 2017-11-29 TR TR2017/19103A patent/TR201719103A2/tr unknown
• 2018
  • 2018-10-02 WO PCT/EP2018/076816 patent/WO2019105633A1/en unknown
  • 2018-10-02 EP EP18782055.0A patent/EP3718196A1/en not_active Withdrawn

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