Patent Application
20230110808
The present disclosure relates generally to a rotor shaft disconnect clutch assembly for an electric axle.
The electric axle includes two gearbox input shafts 12 and 14. Left gearbox 16 drives left wheel 18 at a fraction of the speed of left gearbox input shaft 12. The left motor includes a left stator 20 and a left rotor 22 which is fixed to the left gearbox input shaft 12. Similarly, right gearbox 24 drives right wheel 26 at a fraction of the speed of right gearbox input shaft 14. The right motor includes a right stator 28 and a right rotor 30 which is fixed to the right gearbox input shaft 14. Clutch 32 selectively couples the two gearbox input shafts to one another.
To activate the first operating mode, clutch 32 is released. The left motor drives left wheel 18 and the right motor drives right wheel 26. The speeds of the wheels may differ. The torque applied to the two wheels is controlled independently. To activate the second operating mode, clutch 32 is engaged. The speeds of the two wheels are constrained to be equal. Power from either motor is divided between the wheels but necessarily equally. If one wheel loses traction, the motor power is routed predominantly to the other wheel.
Although only one of the motors is required in the second operating mode, the second rotor will rotate with the respective gearbox input shaft. This adds parasitic losses, especially if the motor is a permanent magnet motor, which is common in many applications. Parasitic losses would be reduced substantially if the unused motor could be disconnected from the shaft. This same issue also arises in other electrified powertrain configurations. For example, if four motors are provided, one for each wheel, the vehicle may operate in a mode in which only the front wheels or only the rear wheels provide propulsion. Some vehicles utilize an electrified axle in the rear and a conventional powertrain in the front. Such vehicles may have operating modes in which the electrified axle is not used for propulsion and disconnecting the motor or motors would significantly reduce parasitic drag.
In embodiments, a rotor shaft disconnect clutch assembly includes a housing, a rotor supported for rotation with respect to the housing and a shaft supported for rotation with respect to the housing. An outer ring may be fixed to the rotor and have a radially inner surface. A slipper ring may be disposed radially between the outer ring and the shaft. A plurality of rollers may be disposed between the radially inner surface of the outer ring and the radially outer surface of the slipper ring that is configured to radially compress the slipper ring in response to rotational displacement of the slipper ring relative to the outer ring. An armature may be rotationally fixed to the rotor and configured to slide axially with respect to the rotor. The armature may have a feature configured to selectively engage a feature of the slipper ring to rotationally position the slipper ring with respect to the outer ring. A solenoid may be fixed to the housing and configured to selectively exert an axial force on the armature.
Embodiments further include that the shaft is disengaged from the outer ring and the rotor when the feature of the armature is engaged with the feature of the slipper ring. The shaft is coupled to the outer ring and the rotor when the feature of the armature is disengaged from the feature of the slipper ring allowing rotational displacement of the slipper ring relative to the outer ring. The assembly may include a spring configured to bias the armature toward the slipper ring such that the feature of the armature is engaged with the feature of the slipper ring. In response to the solenoid exerting the axial force on the armature, the armature slides axially away from the slipper ring overcoming a force exerted by the spring to disengage the feature of the armature from the feature of the slipper ring thereby coupling the shaft to the outer ring and rotor. The feature of the armature may be a protrusion, the feature of the slipper ring may be a notch, and the protrusion may be configured to selectively engage with the notch. The radially inner surface of the outer ring may be designed as a wavy contoured surface. The radially outer surface of the slipper ring may be designed as a wavy contoured surface. The rotor may be supported for rotation via first and second bearings disposed on axially opposite sides of the outer ring.
Embodiments of the present disclosure are described herein. It should be appreciated that like drawing numbers appearing in different drawing views identify identical, or functionally similar, structural elements. Also, it is to be understood that the disclosed embodiments are merely examples and other embodiments can take various and alternative forms. The figures are not necessarily to scale; some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the embodiments. As those of ordinary skill in the art will understand, various features illustrated and described with reference to any one of the figures can be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be desired for particular applications or implementations.
The terminology used herein is for the purpose of describing particular aspects only, and is not intended to limit the scope of the present disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure belongs. Although any methods, devices or materials similar or equivalent to those described herein can be used in the practice or testing of the disclosure, the following example methods, devices, and materials are now described.
In an alternative embodiment, not pictured, the slipper clutch assembly may include an inner ring fixed to the shaft and a slipper ring that expands radially to grip the rotor. In this case, the armature would be fixed for rotation to the shaft as opposed to the rotor.
In another alternative embodiment, the spring may bias the armature away from the slipper clutch assembly and the solenoid may be energized to force the armature toward the slipper clutch assembly into engagement with the slipper ring.
While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The words used in the specification are words of description rather than limitation, and it is understood that various changes can be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments can be combined to form further embodiments of the disclosure that may not be explicitly described or illustrated. While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics can be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. As such, to the extent any embodiments are described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics, these embodiments are not outside the scope of the disclosure and can be desirable for particular applications.
This application claims the benefit of U.S. Provisional Patent Application No. 63/253,620, filed Oct. 8, 2021, the disclosure of which is incorporated in its entirety by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 63253620 | Oct 2021 | US |
