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CN-122026650-A - Electric motor rotor, in particular for a synchronous motor for motor vehicle traction

CN122026650ACN 122026650 ACN122026650 ACN 122026650ACN-122026650-A

Abstract

An electric motor rotor, in particular for an electric motor for motor vehicle traction, having two shaft portions opposite each other and supported by respective bearings, one of the shaft portions defining an inlet and an outlet for a heat exchange liquid, for cooling an annular wall supporting a plurality of permanent magnets and radially defining an inner cavity engaged by a core, the core having an axial bore communicating with the inlet (7) for supplying a plurality of heat exchange channels separated from each other and configured to direct the liquid in a radial direction through a delivery connection channel, the liquid being subsequently directed in an axial direction towards the outlet through a return connection channel separated from each other, the delivery connection channel and/or the return connection channel being defined by two surfaces axially opposite each other and respectively defining a portion of the core and a portion of a body different from the core.

Inventors

  • Giacomo Debenidetis
  • Matteo Qatar Di
  • Enrico Delafenache
  • Simon Peyronie

Assignees

  • 法拉利股份有限公司

Dates

Publication Date
20260512
Application Date
20251111
Priority Date
20241111

Claims (15)

  1. 1. An electric motor rotor (1), in particular for a motor vehicle traction electric motor, the electric motor rotor (1) extending along a longitudinal axis (3) and comprising: -a first shaft portion (4) and a second shaft portion (5) axially opposite each other, adapted in use to be supported for rotation about said longitudinal axis (3) by respective bearings; -an inlet (7) and an outlet (8) for a heat transfer liquid, located at the first shaft part (4); -an annular wall (10) coaxial with said shaft portions (4, 5) and supporting a plurality of permanent magnets (13); -an inner cavity (23) radially delimited by said annular wall (10); -a core (24) housed in said inner cavity (23) and having: a) -at least one feed hole (45) extending along the longitudinal axis (3) and communicating with the inlet (7); b) -a plurality of heat exchange channels (28) for cooling the annular wall (10) and/or the permanent magnets (13); -a transport connection channel (44) separate from each other, providing communication between the supply hole (45) and the heat exchange channel (28), and configured to direct a heat transfer liquid in a radial direction; -return connection channels (38) separate from each other, providing communication between the heat exchange channels (28) and the outlet (8), and configured to direct heat exchange liquid in an axial direction; Wherein the method comprises the steps of -Said delivery connection channel (44) being defined by a first surface (43) and a second surface (42) axially opposite each other and forming a part of said core (24) and of a first body different from said core (24), respectively, and/or -The return connection channel (38) is defined by a third surface (35) and a fourth surface (36) axially opposite each other and constituting a portion of the core (24) and a portion of a second body (20) different from the core (24), respectively.
  2. 2. The motor rotor of claim 1, wherein -The second surface (42) of the first body is a smooth surface and the first surface (43) of the core (24) is provided with ribs (46) which circumferentially separate the conveying connection channels (44) from each other, and/or -The fourth surface (36) of the second body (20) is a smooth surface and the second surface (35) of the core (24) is provided with ribs (46) which circumferentially separate the return connection channels (38) from each other.
  3. 3. The motor rotor according to claim 1, wherein the feed connection channel (44) and/or the return connection channel (38) radiate outwards from the longitudinal axis (3).
  4. 4. The motor rotor of claim 1, wherein -The second surface (42) of the first body and the first surface (43) of the core (24) have curved profiles matching each other, and/or -The fourth surface (36) of the second body and the second surface (35) of the core (24) have curved profiles matching each other.
  5. 5. The electric machine rotor according to any one of the preceding claims, wherein the first body is defined by an insert (41) at least partially housed within the second shaft portion (5) and coaxial with the core (24).
  6. 6. The electric machine rotor of claim 5, wherein the core (24) and/or the insert (41) comprise a plastic material.
  7. 7. The electric machine rotor according to claim 5, wherein the core (24) and/or the insert (41) are configured such that they can be manufactured by molding techniques.
  8. 8. The electric machine rotor according to any one of claims 1 to 4, wherein the inner cavity (23) is axially delimited by a first flange (14), and wherein the fourth surface (36) engages an inner side surface (16) of the first flange (14) with an inner cylindrical surface of the first shaft portion (4).
  9. 9. The electric machine rotor according to claim 8, wherein the second body (20) is a metal body comprising the first flange (14) and the first shaft portion (4).
  10. 10. The electric machine rotor according to any one of claims 1 to 4, wherein the inner cavity (23) is axially delimited by a second flange (15), and wherein the second flange (15), the annular wall (10) and the second shaft portion (5) define a portion of another metal body (22).
  11. 11. The motor rotor according to any one of claims 1 to 4, wherein the feed aperture (45) is centrally located along the longitudinal axis (3), corresponds to the delivery connection channel (44), and engages with a fin (55) so as to be divided into a plurality of axial channels (56) parallel to each other.
  12. 12. The electric machine rotor of claim 11, wherein the fins (55) define a portion of the core (24).
  13. 13. The electric machine rotor according to any one of claims 1 to 4, wherein the core (24) defines a portion of another insert (32), an axial end of the insert (32) being provided with a shank (33) housed in the first shaft portion (4), and wherein the return connection channel (38) communicates with the outlet (8) through a gap (39), the gap (39) being defined radially by an inner cylindrical surface of the first shaft portion (4).
  14. 14. The motor rotor according to claim 13, wherein the gap (39) is divided in the circumferential direction into a plurality of return channels (40) parallel to each other.
  15. 15. The electric machine rotor according to claim 13, wherein the first shaft portion (4) is engaged with an interface element coaxial with the shank portion (33) and the axial bore of which defines the inlet (7), the outlet (8) being defined between the interface element and an inner cylindrical surface of the first shaft portion (4).

Description

Electric motor rotor, in particular for a synchronous motor for motor vehicle traction Cross Reference to Related Applications This patent application claims priority from italian patent application number 102024000025269 filed 11/2024, the entire disclosure of which is incorporated herein by reference. Technical Field The present invention relates to a motor rotor. In particular, the present disclosure relates to an electric machine defined by a motor for traction of a motor vehicle, for which no loss of generality is intended. Background In motor vehicle traction, synchronous electric motors, i.e. electric motors with permanent magnets, are generally used. In particular, brushless motors can be used in which permanent magnets are fixed to a supporting wall that is part of the rotor, while the stator comprises windings that are energized to produce a rotating magnetic field, which in turn drives the permanent magnets and thus the entire rotor. Some electric motors are cooled using a liquid heat exchange system, for example, with channels provided in the stator. However, from a heating point of view, the application in connection with motor vehicle traction is relatively harsh, the non-wheel being in terms of heat generation by currents in the stator windings and in terms of heat generation by eddy currents in the permanent magnets and in the region of the permanent magnet support surfaces. Therefore, not only the stator but also the rotor need to be cooled in order to prevent the heat generation to a level that would impair the efficiency of the motor or even its operation. For this purpose, the rotor has a shaft extending along the axis of rotation, in which shaft an inner axial passage must be provided, which communicates with the inlet and the outlet in order to introduce and remove the heat exchange liquid during rotation of the rotor. Furthermore, in order to cool the radially outermost region of the rotor, i.e. the permanent magnets and their supporting walls, the heat exchange liquid has to be directed radially outwards with respect to these axial channels. For this purpose, the total radial flow is preferably divided into a plurality of channels or sectors isolated from each other, each having a relatively limited width in the circumferential direction, in order to avoid or at least limit hydrodynamic losses due to turbulence which may be created by the coriolis accelerations (Coriolis accelerations). At the same time, when the liquid flow is directed into the radial channels starting from the rotor shaft, the local hydrodynamic losses should be limited, thereby reducing the power consumption and the size of the pump supplying the heat exchange liquid. One possible reason for this is that the liquid in the radial channels also has a rotational component (due to the rotor rotating about its axis), whereas in the rotor shaft the liquid flow is essentially axial (assuming it is led into a single central feed channel), i.e. flows along the rotational axis. Under these conditions, when the liquid flow enters the radial channels, its movement state changes suddenly, causing a hydrodynamic loss. To overcome this disadvantage, it is advantageous to divide the liquid flow in the rotor shaft into a number of axial channels which are isolated from each other so that the liquid flow already has a rotational movement component in the rotor shaft. Patent application US 2015/288255 A1, corresponding to the preamble of claim 1, discloses such a solution, wherein a plurality of axial feed channels and a plurality of return channels are provided in the rotor shaft. Another reason for the localized losses is the abrupt change in flow direction of the liquid as it is directed from the rotor shaft into the radial channels. In the document US 2015/288255 A1, the axial channels end in respective orifice areas, which are machined in the rotor shaft by means of a mechanical tool, the direction being essentially radial. Thus, when the liquid flow in the rotor shaft enters these apertures, the direction changes suddenly, with the angle of change being a right angle. The same applies when the liquid flow flows back radially into the rotor shaft. As mentioned before, abrupt changes in these flow directions can lead to localized hydrodynamic losses, which should be avoided. In other words, it is necessary to couple the axial channels with the radial channels by a relatively large bending radius compared to US 2015/288255 A1, so that the flow direction change is less abrupt. In addition to reducing hydrodynamic losses, other objectives are achieved compared to known solutions, such as for example, completing the manufacture and/or assembly of the rotor by relatively simple, economical and time-consuming operations, improving the versatility of the rotor assembly design, improving the characteristics of the channels circumferentially spaced from each other, maximizing the heat exchange with the rotor assembly, improving the confi