Patent ID: 12218550

DETAILED DESCRIPTION

This disclosure details exemplary assemblies and methods for managing thermal energy levels within an electric machine, and particularly a rotor of the electric machine. A coolant circuit within the electric machine can communicate coolant through the electric machine in a way that facilitate, among other things, evenly cooling the electric machine.

A rotor of an electric motor is typically a rotating part of the electric motor that rotates due magnetic fields. The rotation of the rotor develops a torque about an axis of the rotor. During the rotation of the rotor, thermal energy levels in the electric machine can increase due to, among other things, changing magnetic fields. Conventionally, a coolant (lubricating oil or lube oil) is circulated through the electric motor. The coolant can move along a coolant circuit within the electric motor. The coolant cools and lubricating the rotor and other components, such as stator end windings and permanent magnets of the electric motor.

With reference toFIG.1, an electrified vehicle10includes a traction battery14, an electric machine18, and wheels22. The traction battery14powers the electric machine18, which converts electrical power to torque to drive the wheels22.

The electrified vehicle10includes a charge port26. The electrified vehicle10can be electrically coupled an external power source through the charge port26. The traction battery14can be recharged from the external power source.

The traction battery14is, in the exemplary embodiment, secured to an underbody of the electrified vehicle10. The traction battery14could be located elsewhere on the electrified vehicle10in other examples.

The electrified vehicle10is an all-electric vehicle. In other examples, the electrified vehicle10is a hybrid electric vehicle, which can selectively drive wheels using torque provided by an internal combustion engine instead, or in addition to, an electric machine. Generally, the electrified vehicle10can be any type of vehicle having a traction battery and an electric machine.

With reference now toFIGS.2and3, the electric machine18includes a shaft30, a rotor34, a stator38, a first endcap42, and a second endcap46. The rotor34is mounted to the shaft30between the first endcap42and the second endcap46. The shaft30, the rotor34, the first endcap42, and the second endcap46are configured to rotate together about an axis X of the electric machine18. The first endcap42is located near a bearing (not shown). The second endcap46is located near the point from where the lube oil enters the shaft30.

Referring now toFIGS.4and5with continuing reference toFIGS.2and3, the electric machine18includes a coolant circuit50. A liquid coolant can be moved along the coolant circuit50to manage thermal energy levels within the electric machine18.

The shaft30is a hollow shaft that has a shaft channel54. Coolant, such as a liquid coolant, can be communicated from the shaft channel54through a plurality of radially extending bores58, through at least one radially inner coolant channel62, through at least one endcap coolant channel66, through at least one radially outer coolant channel70, and then through an endcap exit opening74. The coolant can be communicated to the shaft channel54of the shaft30from a coolant supply78.

In this example, the radially extending bores58are disposed equidistant from the first endcap42and the second endcap46, and are at an axial center of the rotor34. The radially extending bores58receive coolant from the shaft channel54, and communicate the coolant radially to one of the radially inner coolant channels62.

The radially inner coolant channels62are, in this example, grooves within the shaft30. In another example, the radially inner coolant channels62could be provided, or partially provided, by grooves in the rotor34.

The grooves with the shaft30open radially outward. The radially inner coolant channels62have a rectangular cross-sectional profile in this example. Within the radially inner coolant channels62some of the coolant moves in an axial direction D1between the shaft30and the rotor34toward the first endcap42, and some of the coolant moves in an axial direction D2between the shaft30and the rotor34toward the second endcap46. The axial direction D1is opposite the axial direction D2.

The endcap coolant channel66within the first endcap42receives the coolant that has moved in the axial direction D1from the radially inner coolant channels62. The endcap coolant channel66within first endcap42receives the coolant that has moved in the axial direction D1from the radially inner coolant channels62. The endcap coolant channel66within second endcap46receives the coolant that has moved in the axial direction D2from the radially inner coolant channels62. From the endcap coolant channels66, the coolant is delivered to the radially outer coolant channels70.

The endcap coolant channels66are open to the rotor34. The endcap coolant channels66each include an annular portion80and a plurality of spoke portions84. The annular portion80is radially aligned with the radially inner coolant channels62and is disposed about the axis X. The spoke portions84extend radially from the annular portion80to the radially outer coolant channels70. In this example, the spoke portions84taper downward moving radially outward away from the annular portion80.

The radially outer coolant channels70each have a triangular cross-sectional profile. The radially outer coolant channels70are circumferentially distributed about the axis X. The radially outer coolant channels70are radially outside the radially inner coolant channels62. The radially outer coolant channels70can be repurposed air channels of the rotor34.

The radially outer coolant channels70include a plurality of first radially outer coolant channels70A, and a plurality of second radially outer coolant channels70B. The plurality of first radially outer coolant channels70A are circumferentially offset from the plurality of second radially outer coolant channels70B.

The plurality of first radially outer coolant channels70A each receive coolant from one of the spoke portions84of the endcap coolant channel66in the first endcap42. The plurality of first radially outer coolant channels70A communicate the coolant axially in the axial direction D1from the first endcap42on a first axial side of the rotor34to the second endcap46on an opposite second axial side of the rotor34. The coolant then moves through one of the endcap exit openings74in the second endcap46and sprays onto windings92of the electric machine18.

The plurality of second radially outer coolant channels70B each receive coolant from one of the spoke portions84of the endcap coolant channel66in the second endcap46. The plurality of second radially outer coolant channels70B communicate the coolant axially in the axial direction D2from the second endcap46on a second axial side of the rotor34to the first endcap42on the first axial side of the rotor34. The coolant then moves through one of the endcap exit openings74in the second endcap46and sprays onto the windings92of the electric machine18.

The coolant circuit50facilitates evenly distributing coolant within the electric machine18and particularly the rotor34. Also, the flow bias at relatively elevated rotor speeds can be reduced or eliminated when using the exemplary coolant circuit of this disclosure.

Features of the disclosed examples include a coolant supply system that can facilitate temperature reductions in the rotor material and nearby components, such as magnets.

The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this disclosure. Thus, the scope of protection given to this disclosure can only be determined by studying the following claims.