Compact EV Powertrain with Coaxial Gears and Nested Bearings
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Solution Overview
Problem
Current electric vehicle powertrains face challenges in achieving high power density within a reduced envelope, leading to increased complexity, weight, and emissions due to the inclusion of internal combustion engines and complex drivetrains, while also compromising on performance, range, reliability, and cost.
Innovation Solution
A high power density electric vehicle powertrain design that integrates a stator with rectangular cross-section windings, a rotor lamination stack with clamped lamination layers and rivets, and an inside-out bearing arrangement, along with coaxially aligned planetary gear assemblies and CV joint components, to minimize volume and maximize space efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a hybrid drivetrain with internal combustion engine and electric motor is used, then fuel efficiency and emissions are improved, but drivetrain complexity and weight increase
Solution Approach 1:
The patent removes the internal combustion engine from the drivetrain, extracting only the necessary electric motor components while eliminating the complex mechanical systems of hybrid vehicles. This extraction approach maintains emissions benefits while reducing drivetrain complexity to that of a conventional single-powertrain system.
Solution Approach 2:
The electric motor is designed to perform multiple functions - providing both propulsion and energy recovery capabilities that were previously distributed between the ICE and electric motor in hybrid systems. This multi-functionality consolidates the drivetrain into a simpler single-powertrain architecture.
2Reliability
If traditional bearing arrangements are used in the rotor, then rotor support is provided, but additional bearing volume increases powertrain width
Solution Approach 1:
The patent merges the bearing support function directly into the rotor structure by mounting bearings to the rotor shaft itself rather than using separate bearing housings. This integration eliminates additional bearing volume and reduces powertrain width while maintaining reliable rotor support.
Solution Approach 2:
The bearings are nested within the rotor assembly, with bearing races mounted directly to the rotor shaft in a compact arrangement. This nesting approach allows the bearing support function to be contained within the existing rotor volume rather than adding external bearing housings that would increase width.
3Power
If conventional powertrain designs are used, then adequate power delivery is achieved, but overall width and envelope are increased
Solution Approach 1:
The patent transitions from a conventional wide powertrain layout to a compact arrangement by reorganizing components in the axial dimension. The planetary gear assemblies are positioned coaxially with the rotor, and CV joint components are arranged to minimize radial width while maintaining power delivery capability through optimized component stacking.
Solution Approach 2:
The planetary gear assemblies are nested coaxially within the rotor assembly, with gear carriers positioned inside the rotor housing. This nesting arrangement allows the power transmission path to be contained within a smaller radial envelope while maintaining adequate power delivery through efficient gear meshing.
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
The design achieves a compact powertrain with improved CV joint support, reduced width, and increased rpm speed, while eliminating the need for additional bearing volume, resulting in a more efficient, reliable, and environmentally friendly powertrain solution.
Implementation Method 1
a stator containing a plurality of slots, where a plurality of windings occupy the slots
Implementation Method 2
a rotor lamination stack with a plurality of permanent magnets
Implementation Method 3
clamped together with a plurality of rivets
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A powertrain utilizing an active core motor with coaxially aligned planetary-differential-planetary gear assemblies is provided.