US-20260128631-A1 - SYSTEMS FOR ROTOR COOLING

US20260128631A1US 20260128631 A1US20260128631 A1US 20260128631A1US-20260128631-A1

Abstract

Methods and systems are provided for cooling rotor assemblies, particularly rotor assemblies that include a shaftless rotor. In one example, a rotor assembly and cooling system includes cooling channels formed into parts of the rotor assembly, including a rotor core, an end cap, and a cup. In this way, coolant fluid flows axially through the rotor assembly to increase temperature reduction.

Inventors

Adam Bangerter

Assignees

FORD GLOBAL TECHNOLOGIES, LLC

Dates

Publication Date: 20260507
Application Date: 20241105

Claims (20)

1 . A rotor assembly, comprising: a first end cap; a second end cap; a rotor core surrounding a cavity and positioned between the first end cap and the second end cap; and a fastener extending axially along an axis through the first end cap, the second end cap, and the cavity, the fastener affixing the first end cap and the second end cap to the rotor core, where the first end cap and the second end cap have cap cooling channels to distribute a coolant fluid among stack cooling channels extending axially through the rotor core.
2 . The rotor assembly of claim 1 , wherein the cap cooling channels include first cooling channels at a first angle with the axis.
3 . The rotor assembly of claim 2 , wherein the cap cooling channels further include second cooling channels at a second angle greater than the first angle with the axis.
4 . The rotor assembly of claim 2 , wherein the cap cooling channels further include third cooling channels parallel with the axis and the coolant fluid exits the rotor assembly via the third cooling channels.
5 . The rotor assembly of claim 4 , wherein the cap cooling channels further include fourth cooling channels that redirect the coolant fluid in an opposite axial direction from which fluid enters the fourth cooling channels.
6 . The rotor assembly of claim 5 , wherein the stack cooling channels are axially aligned with the first cooling channels at a first end and with the third cooling channels at a second end, or are axially aligned with the fourth cooling channels at the second end and with the third cooling channels at the first end.
7 . The rotor assembly of claim 1 , wherein the coolant fluid does not flow radially through the rotor core.
8 . A rotor assembly, comprising: a rotor core including lamination stacks surrounding a cavity and centered around an axis; a first end cap at a first end of the rotor core, the first end cap including a protrusion adapted to receive a cup; a second end cap at a second end of the rotor core; and a cooling system, comprising: cooling passages in the cup, where fluid enters the rotor assembly via the cooling passages; stack cooling channels through which the fluid flows axially within the lamination stacks; and cap cooling channels through which the fluid flows within the first end cap and the second end cap.
9 . The rotor assembly of claim 8 , wherein the cap cooling channels include first cooling channels formed in the first end cap, third cooling channels formed in the first end cap and in the second end cap, and fourth cooling channels formed in the second end cap, and wherein the first cooling channels include first inner openings that are outwardly radially elongated to deliver fluid to the stack cooling channels.
10 . The rotor assembly of claim 9 , wherein the cap cooling channels further include second cooling channels with second inner openings that are outwardly radially elongated to deliver the fluid to a perimeter of the cavity.
11 . The rotor assembly of claim 9 , wherein a first number of the first cooling channels, a second number of second cooling channels formed in the first end cap, and a third number of the third cooling channels of the first end cap are equal.
12 . The rotor assembly of claim 8 , wherein the cooling passages include cooling holes, and wherein the cooling holes are radially arranged around the axis and fluidly separated from an axially inner opening of the cup.
13 . The rotor assembly of claim 8 , wherein the cooling passages include cooling slots, and wherein the cooling slots are radially arranged around the axis and fluidly coupled to an axially inner opening of the cup.
14 . The rotor assembly of claim 8 , wherein the rotor assembly further comprises a fastener extending axially through a center of the first end cap, through the cavity, and through a center of the second end cap, the fastener affixing the first end cap and the second end cap to the rotor core without any other fasteners.
15 . The rotor assembly of claim 8 , wherein the fluid flows in a first axial direction through some of the stack cooling channels and in a second axial direction through others of the stack cooling channels, the first axial direction being opposite the second axial direction.
16 . The rotor assembly of claim 8 , wherein the first end cap includes a first flange, the second end cap includes a through hole adapted to receive a drive end coupling with a second flange, and the first flange and the second flange extend axially towards each other to axially align the lamination stacks.
17 . The rotor assembly of claim 8 , wherein the cooling system is adapted to distribute the fluid through the rotor assembly and to end windings of a stator assembly circumferentially surrounding the rotor assembly.
18 . An electric machine, comprising: a stator assembly including stator lamination stacks and conductors extending through the stator lamination stacks, the conductors including end windings extending beyond the stator lamination stacks; and a rotor assembly adapted to rotate about an axis, the rotor assembly comprising: a first end cap and a second end cap; a rotor core circumferentially surrounded by the stator lamination stacks and positioned axially between the first end cap and the second end cap; and a fastener extending along the axis and adapted to apply axial force on the first end cap and second end cap, wherein stack cooling channels extend axially through the rotor core parallel to the axis and cap cooling channels extend through the first end cap and the second end cap, and wherein the cap cooling channels are adapted to distribute coolant fluid to the stack cooling channels and distribute fluid to the end windings.
19 . The electric machine of claim 18 , wherein the rotor assembly further comprises a cup including an axially outer opening, an axially inner opening, and cooling holes or cooling slots radially arranged around the axially inner opening.
20 . The electric machine of claim 19 , wherein the cooling holes or the cooling slots axially align with the cap cooling channels formed in the first end cap.

Description

FIELD The present description relates generally to systems for providing cooling to components of a rotor assembly. BACKGROUND/SUMMARY A vehicle, such as a hybrid vehicle or a fully electric vehicle (EV), may use a rotor assembly including a shaft to drive a vehicle in a direction. In previous rotor assemblies, the shaft may extend through a center of a rotor core comprising lamination stacks and be secured to the rotor core via a fastening system comprising components, such as locknuts and washers. A shoulder may be formed at a first end of the shaft, and the lamination stacks may be held together between the shoulder at the first end of the shaft and fastening components coupled to a second end of the shaft. In this way, the shaft extends axially through the lamination stacks of the rotor core to align the lamination stacks and hold the components of the rotor together. A rotor assembly without a conventional shaft may have advantages over a conventional rotor assembly. A rotor assembly without a conventional shaft may be lighter weight and be less complex to manufacture than a conventional rotor assembly which demand a shaft. Rotor assemblies without conventional shafts may use end caps positioned at either axial end of the rotor assembly to hold laminations layers of the rotor assembly in place. It is desirable to ensure adequate cooling on rotors with endcaps. In one example, the issues described above may be addressed by a method for a rotor assembly, comprising a first end cap; a second end cap; a rotor core surrounding a cavity and positioned between the first end cap and the second end cap; and a fastener extending axially along an axis through the first end cap, the second end cap, and the cavity, the fastener affixing the first end cap and the second end cap to the rotor core, where the first end cap and the second end cap have cap cooling channels to distribute a coolant fluid among stack cooling channels extending axially through the rotor core. As one example, the rotor assembly may be circumferentially surrounded by a stator assembly including stator lamination stacks and conductors extending through the stator lamination stacks, the conductors including end windings extending beyond the stator lamination stacks. The cap cooling channels may further distribute fluid to the end windings. In this way, a coolant path may be provided for a rotor assembly which cools both the rotor core and stator end windings. It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an example vehicle powertrain that may comprise a cooling system according to the present disclosure. FIG. 2 shows a schematic diagram of a vehicle comprising the cooling system according to the present disclosure FIG. 3 shows a cross sectional view of a rotor assembly including the cooling system according to the present disclosure. FIG. 4A shows a perspective view of a cup of the cooling system according to the present disclosure. FIG. 4B shows a cross sectional view of the cup of FIG. 4A according to the present disclosure. FIG. 5 shows a perspective view of a cup of the cooling system according to the present disclosure. FIG. 6 shows a perspective view of an outer surface of an end cap of the cooling system according to the present disclosure. FIG. 7 shows a perspective view of an inner surface on the end cap of FIG. 6 according to the present disclosure. FIG. 8 shows a perspective view of the rotor assembly, a stator assembly, and a cooling system according to the present disclosure. FIG. 9 shows a perspective view of an inner surface of an end cap of the cooling system according to the present disclosure. FIG. 10 shows a perspective view of an outer surface of an end cap of the cooling system according to the present disclosure. FIG. 11 shows a cross sectional view of the rotor assembly according to the present disclosure. DETAILED DESCRIPTION The following description relates to systems and methods for distributing coolant to a rotor assembly and a stator circumferentially surrounding the rotor assembly. The rotor assembly may include a single fastener and a shaftless rotor. The shaftless rotor may not include a rotor shaft extending therethrough. Upon fastening the shaftless rotor with the single fastener, the rotor assembly may be formed. End caps and cups positioned at either end may couple to the single fastener and in coupling to the fastener may prevent relative lateral motion of lamination layers of the shaftless rotor. A cooling system may be