Sun Bearing Spherical Rollers Electric Powertrain Friction
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Solution Overview
Problem
Electric drive units in vehicles experience significant friction losses due to bearing inefficiencies, which impact overall efficiency and vehicle range, as conventional designs prioritize larger bearings for load capacity over efficiency.
Innovation Solution
The introduction of a sun bearing with spherical roller elements between inner and outer races, optimizing the bearing arrangement to reduce friction losses by isolating the motor and allowing for smaller motor bearings, while the sun bearing handles thrust loads and has a reduced speed differential, enabling a more efficient powertrain design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If larger bearings are used for load capacity, then bearing load capacity is improved, but friction losses increase
Solution Approach 1:
The bearing system is segmented into two distinct types: conventional bearings for load capacity and a sun bearing with spherical roller elements for efficiency. This segmentation allows each bearing type to be optimized for its specific function, resolving the contradiction between load capacity and friction losses.
Solution Approach 2:
The invention changes the bearing configuration parameters by introducing a sun bearing with spherical roller elements between the inner and outer races. This parameter change enables the system to handle thrust loads while minimizing friction, as the spherical rollers reduce contact friction compared to conventional bearing designs.
2Loss of energy
If sun bearing with spherical roller elements is introduced, then friction losses are reduced, but device complexity increases
Solution Approach 1:
The sun bearing with spherical roller elements serves multiple functions: it handles thrust loads, reduces friction losses, and enables the motor isolation configuration. This multi-functionality justifies the added complexity by delivering multiple benefits from a single component.
Solution Approach 2:
The sun bearing is nested within the planetary gearset structure, with the inner race disposed on the inner bearing seat and the outer race disposed on the outer bearing seat of the planet carrier. This nesting integrates the sun bearing into the existing gearset architecture, minimizing additional complexity.
3Loss of energy
If motor isolation is implemented, then efficiency is improved, but packaging space requirements increase
Solution Approach 1:
The sun bearing is combined with the planetary gearset structure, merging the bearing support function with the existing gear carrier architecture. This integration allows motor isolation for efficiency while avoiding additional packaging space requirements that would result from separate bearing housings.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances drive unit efficiency by minimizing friction losses, allowing for a 1% increase in efficiency corresponding to a 1.7% increase in vehicle range, and facilitates modular design with reduced packaging inefficiencies and noise sensitivity.
Implementation Method 1
A sun bearing is supported about the axis and includes an outer race disposed on the outer bearing seat, an inner race disposed on the inner bearing seat, and a plurality of spherical roller elements disposed between the inner and outer races
Data Source
AI summary
An electric powertrain includes an electric machine having a rotor shaft supported for rotation about an axis. A planetary gearset is supported about the axis and includes a sun gear assembly having a sun shaft with a first end connected to the rotor shaft, a second end having a sun gear, and an inner bearing seat disposed therebetween. The planetary gearset further includes a planet carrier having planet gears and defining an outer bearing seat. At least one of the planet gears meshes with the sun gear. The planetary gearset also includes a ring gear meshing with at least one of the planet gears. A sun bearing is supported about the axis and includes an outer race disposed on the outer bearing seat, an inner race disposed on the inner bearing seat, and a plurality of spherical roller elements disposed between the inner and outer races.