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US-12627185-B2 - Rotor for an electric motor provided with a cooling circuit

US12627185B2US 12627185 B2US12627185 B2US 12627185B2US-12627185-B2

Abstract

A rotor having channels for circulating a cooling fluid, a rotor shaft which is mounted for rotation about an axis, and a lamination stack which is mounted coaxially on the shaft. The lamination stack includes first internal cavities and second internal cavities which are symmetrical relative to the axis of the shaft and relative to each other. The two second internal cavities extend axially through the whole of the lamination stack so that they open, at the first end, into a front lateral face of the lamination stack and, at the other end, into a rear lateral face. The two second internal cavities are configured to allow a cooling fluid to circulate inside the lamination stack. A plurality of permanent magnets are received inside the first internal cavities. A front flange and a rear flange which are mounted coaxially on the shaft are arranged on either side of the lamination stack so as to be contiguous with the front and rear lateral faces, respectively.

Inventors

  • Cédric Ledieu

Assignees

  • NOVARES FRANCE

Dates

Publication Date
20260512
Application Date
20210520
Priority Date
20200529

Claims (18)

  1. 1 . A rotor for an electric motor comprising: a rotor shaft rotatably mounted about an axis; a lamination stack coaxially mounted on the rotor shaft, the lamination stack comprising first internal cavities and at least two second internal cavities symmetrical with respect to the axis of the shaft and to each other, the at least two second internal cavities passing axially through the entire lamination stack so that they open, at one of their ends, at a front lateral face of the lamination stack and, at another one of their ends, at a rear lateral face of the lamination stack, the at least two second internal cavities being configured to enable the circulation of a coolant inside the lamination stack; a plurality of permanent magnets housed inside the first internal cavities of the lamination stack; a front flange and a rear flange coaxially mounted on the rotor shaft and axially arranged on either side of the lamination stack so as to be contiguous respectively to the front and rear lateral faces of the lamination stack; wherein the shaft is provided with at least one first internal channel for circulating a coolant, called the inlet channel, and with at least one second internal channel for circulating a coolant, called the outlet channel, and wherein the front flange, respectively the rear flange, is configured to form with the front lateral face, respectively the rear lateral face, of the lamination stack at least two front connecting channels, respectively at least two rear connecting channels, inside which a coolant can circulate, each of the at least two front connecting channels, respectively of the at least two rear connecting channels, being in fluid communication with one of the inlet and outlet channels and with one of the at least two second internal cavities; wherein the at least two rear connecting channels are in fluid communication with the inlet channel and the at least two front connecting channels are in fluid communication with the outlet channel, so that a coolant intended for the cooling of the rotor can circulate in the rotor successively through the inlet channel, then between the rear flange and the rear lateral face of the lamination stack through the at least two rear connecting channels, then inside the lamination stack through the at least two second internal cavities, then between the front flange and the front lateral face through the at least two front connecting channels, and finally through the outlet channel; and wherein the shaft comprises a hollow front end portion and a solid rear end portion separated from the front end portion by a hollow central portion, the front end portion and the central portion being crossed by a cylindrical-shaped central cavity, the central cavity forming the inlet channel of the shaft, the front end portion further having at least one peripheral cavity formed within the front end portion of the shaft and coaxially aligned with the central cavity, the at least one peripheral cavity forming the outlet channel of the shaft, and wherein at least two holes radially oriented with respect to the axis of the shaft are formed inside the front end portion, respectively the central portion, so as to open, on one side, into the outlet channel, respectively the inlet channel, and, on the other side, into the at least two front connecting channels, respectively the at least two rear connecting channels.
  2. 2 . The rotor according to claim 1 , wherein the at least two front connecting channels are in fluid communication with the inlet channel and the at least two rear connecting channels are in fluid communication with the outlet channel, so that a coolant intended for the cooling of the rotor can circulate in the rotor successively through the inlet channel, then between the front flange and the front lateral face of the lamination stack through the at least two front connecting channels, then inside the lamination stack through the at least two second internal cavities, then between the rear flange and the rear lateral face of the lamination stack through the at least two rear connecting channels, and finally through the outlet channel.
  3. 3 . The rotor according to claim 2 , wherein the shaft comprises a hollow front end portion and a hollow rear end portion separated from the front end portion by a solid central portion, the front end portion, respectively the rear end portion, being crossed by a cylindrical-shaped central cavity, the central cavity forming the inlet channel, respectively the outlet channel, of the shaft, and wherein at least two holes radially oriented with respect to the axis of the shaft are formed inside the front end portion, respectively of the rear end portion, so as to open, on one side, into the inlet channel, respectively the outlet channel, and, on the other side, into the at least two front connecting channels, respectively the at least two rear connecting channels.
  4. 4 . The rotor according to claim 3 , wherein each of the front and rear flanges has an internal face in contact with a lateral face of the lamination stack, the internal face being provided with at least two oblong-shaped grooves extending radially from a recessed central region of the flange, at which the grooves are in fluid communication with the inlet or outlet channel of the shaft, to an intermediate region of the flange facing one of the at least two second internal cavities of the lamination stack.
  5. 5 . The rotor according to claim 2 , wherein each of the front and rear flanges has an internal face in contact with a lateral face of the lamination stack, the internal face being provided with at least two oblong-shaped grooves extending radially from a recessed central region of the flange, at which the grooves are in fluid communication with the inlet or outlet channel of the shaft, to an intermediate region of the flange facing one of the at least two second internal cavities of the lamination stack.
  6. 6 . The rotor according to claim 1 , wherein the shaft comprises a main body provided with a blind hole aligned along the axis of the shaft, the blind hole comprising two contiguous sections with different internal diameters, namely a first section having a first internal diameter and a second section having a second internal diameter, and wherein an insert made of plastic material is housed inside the blind hole at the first section, the insert being formed of a tubular part aligned with the second section of the blind hole and having an internal diameter which is substantially equal to the second internal diameter, and of an annular part extending radially about one of the ends of the tubular part, the annular part being positioned at the interface between the first section and the second section of the blind hole and having an external diameter which is substantially equal to the first internal diameter, the inlet channel of the shaft being jointly defined by the tubular part of the insert and by the second section of the blind hole and the outlet channel of the shaft corresponding to the space delimited by the first section of the blind hole and by the tubular and annular parts of the insert.
  7. 7 . The rotor according to claim 6 , wherein the insert comprises one or several separation fins extending radially from the external periphery of the tubular part, each of the separation fins being configured to separate the outlet channel into two or several segments of outlet channels.
  8. 8 . The rotor according to claim 7 , wherein each of the front and rear flanges has an internal face in contact with a lateral face of the lamination stack, the internal face being provided with at least two oblong-shaped grooves extending radially from a recessed central region of the flange, at which the grooves are in fluid communication with the inlet or outlet channel of the shaft, to an intermediate region of the flange facing one of the at least two second internal cavities of the lamination stack.
  9. 9 . The rotor according to claim 8 , wherein each of the radial grooves faces a radial hole formed through the shaft, the radial hole opening, on one side, onto the inlet or outlet channel of the shaft and, on the other side, onto the peripheral wall of the shaft.
  10. 10 . The rotor according to claim 9 , wherein each of the front and rear flanges is provided on its internal face with a circular groove intended to house a ring-shaped gasket, the gasket being intended to provide sealing between the flange and the lamination stack.
  11. 11 . The rotor according to claim 10 , wherein the front flange, respectively the rear flange, is configured to form with the front lateral face, respectively the rear lateral face, of the lamination stack several groups of front connecting channels, respectively several groups of rear connecting channels, each of the groups including at least two front connecting channels, respectively at least two rear connecting channels, inside which a coolant can circulate, each of the at least two front connecting channels, respectively of the at least two rear connecting channels, being in fluid communication with one of the inlet and outlet channels and with one of the at least two second internal cavities.
  12. 12 . The rotor according to claim 11 , wherein the front flange, respectively the rear flange, is configured to form with the front lateral face, respectively the rear lateral face, of the lamination stack several front intermediate channels, respectively several rear intermediate channels, inside which a coolant can circulate, each of the front intermediate channels, respectively of the rear intermediate channels, being axially aligned with a radial segment of the lamination stack separating two adjacent second internal cavities, each of the front, respectively rear, intermediate channels being in fluid communication with one of the inlet and outlet channels and with a through hole formed through the lamination stack, the through hole possibly receiving a fastening screw intended to fasten the front and rear flanges on the lamination stack.
  13. 13 . The rotor according to claim 1 , wherein each of the front and rear flanges has an internal face in contact with a lateral face of the lamination stack, the internal face being provided with at least two oblong-shaped grooves extending radially from a recessed central region of the flange, at which the grooves are in fluid communication with the inlet or outlet channel of the shaft, to an intermediate region of the flange facing one of the at least two second internal cavities of the lamination stack.
  14. 14 . The rotor according to claim 13 , wherein each of the radial grooves faces a radial hole formed through the shaft, the radial hole opening, on one side, onto the inlet or outlet channel of the shaft and, on the other side, onto the peripheral wall of the shaft.
  15. 15 . The rotor according to claim 1 , wherein each of the front and rear flanges is provided on its internal face with a circular groove intended to house a ring-shaped gasket, the gasket being intended to provide sealing between the flange and the lamination stack.
  16. 16 . The rotor according to claim 1 , wherein the front flange, respectively the rear flange, is configured to form with the front lateral face, respectively the rear lateral face, of the lamination stack several groups of front connecting channels, respectively several groups of rear connecting channels, each of the groups including at least two front connecting channels, respectively at least two rear connecting channels, inside which a coolant can circulate, each of the at least two front connecting channels, respectively of the at least two rear connecting channels, being in fluid communication with one of the inlet and outlet channels and with one of the at least two second internal cavities.
  17. 17 . The rotor according to claim 16 , wherein the front flange, respectively the rear flange, is configured to form with the front lateral face, respectively the rear lateral face, of the lamination stack several front intermediate channels, respectively several rear intermediate channels, inside which a coolant can circulate, each of the front intermediate channels, respectively of the rear intermediate channels, being axially aligned with a radial segment of the lamination stack separating two adjacent second internal cavities, each of the front, respectively rear, intermediate channels being in fluid communication with one of the inlet and outlet channels and with a through hole formed through the lamination stack, the through hole possibly receiving a fastening screw intended to fasten the front and rear flanges on the lamination stack.
  18. 18 . An electric motor comprising a rotor according to claim 1 .

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a National Stage of PCT Application No. PCT/FR2021/050921 filed on May 20, 2021, which claims priority to French Patent Application No. 20/05691 filed on May 29, 2020, the contents each of which are incorporated herein by reference thereto. TECHNICAL FIELD The invention concerns a rotor for an electric motor arranged to enable a better removal of the heat generated during its operation. The invention also concerns an electric motor comprising such a rotor. BACKGROUND In general, the current electric motors include a rotor secured to a shaft and a stator which surrounds the rotor. The stator is mounted in a casing which includes bearings for the rotational mounting of the shaft. The rotor includes a body formed by a bundle of laminations or polar wheels (claw pole) held in the form of a stack by means of a suitable fastening system. The body of the rotor includes internal cavities housing permanent magnets. The stator includes a body consisting of a bundle of laminations forming a crown, the internal face of which is provided with teeth delimiting two by two a plurality of slots open towards the inside of the stator body and intended to receive phase windings. These phase windings pass through the slots of the stator body and form winding heads projecting on either side of the stator body. The phase windings may for example consist of a plurality of U-shaped conductor segments, the free ends of two adjacent segments being connected to each other by welding. In the rotor, the lamination stack is axially clamped between a front flange and a rear flange which are mounted coaxially with the shaft. Each flange generally has the shape of a disc extending in a radial plane perpendicular to the axis of the shaft. Each flange includes a central orifice for the coaxial mounting on the shaft and several through holes intended to receive fastening screws passing axially through the entire lamination stack, said screws being secured to the flanges by means of nuts. The front and rear flanges are generally formed of a non-magnetic, heat-conducting material, for example a metal. The casing generally includes front and rear bearings assembled together. The bearings define an internal cavity in which the rotor and the stator are housed. Each of the bearings centrally carries a ball bearing for the rotational mounting of the shaft of the rotor. During the operation of the motor, the current flowing through the phase windings of the stator generates significant heat that must be removed. To cool the motor, there are currently several solutions. One of these solutions is to circulate oil through the shaft of the rotor and then to circulate this oil along the stator body so that it is in contact with the winding heads of the phase windings. Such a solution, however, requires providing for numerous modifications in the structure of the motor, which makes it difficult to implement, and, therefore, relatively expensive. Another existing solution consists in providing for a cooling circuit inside the bearing with which the stator is crimped, a coolant circulating inside the cooling circuit making it possible to remove the heat generated by the stator via the bearing. However, this solution has the disadvantage of being relatively expensive and complex to implement due to the use of specific bearings incorporating an internal cooling circuit. BRIEF SUMMARY The invention therefore aims to provide a rotor and an electric motor comprising such a rotor arranged to enable a better removal of heat generated during its operation and does not have the disadvantages of the existing solutions described above. To this end, the invention concerns a rotor for an electric motor comprising: a rotor shaft rotatably mounted about an axis;a lamination stack coaxially mounted on the rotor shaft, said lamination stack comprising first internal cavities and at least two second internal cavities symmetrical with respect to the axis of the shaft and to each other, said at least two second internal cavities passing axially through the entire lamination stack so that they open, at one of their ends, at a front lateral face of said lamination stack and, at another one of their ends, at a rear lateral face of said lamination stack, said at least two second internal cavities being configured to enable the circulation of a coolant inside the lamination stack;a plurality of permanent magnets housed inside the first internal cavities of the lamination stack;a front flange and a rear flange coaxially mounted on the rotor shaft and axially arranged on either side of the lamination stack so as to be contiguous respectively to the front and rear lateral faces of the lamination stack;characterized in that the shaft is provided with at least one first internal channel for circulating a coolant, called the inlet channel, and with at least one second internal channel for circulating a coolant, called the outlet c