Lubricant-Supported Wheel-End Motor Assembly With Nested Planetary Gears
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Solution Overview
Problem
Existing wheel-end electric motors are bulky and heavy, consuming valuable space and increasing the overall mass and weight of vehicles, while failing to adequately address high shock and vibration requirements and other considerations such as torque density, power density, and cost efficiency in wheel-end electric drive vehicular powertrain applications.
Innovation Solution
A modular lubricant-supported electric motor assembly comprising an electric motor module, a shifting and first stage module, and a final drive module, which includes a stator and rotor with lubricant support, planetary gear reducers, and a shifting mechanism to provide adjustable drive torque, allowing for compact size, lighter weight, and improved torque and power density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wheel-end electric motors incorporate large, heavy components to meet shock and vibration requirements, then robustness to shock and vibration is improved, but the motor becomes heavy and bulky, consuming valuable space and increasing overall vehicle mass
Solution Approach 1:
The motor is divided into modular components (stator, rotor, planetary gear set, hub assembly) that can be independently optimized. This segmentation allows each component to be sized appropriately for its function rather than requiring the entire motor to be oversized for shock resistance, thereby reducing overall mass while maintaining robustness through strategic placement of reinforcement in critical areas.
Solution Approach 2:
The planetary gear set is nested within the motor housing, and the hub assembly is integrated with the rotor structure. This nesting eliminates the need for separate mounting structures and support components, reducing the overall motor envelope and mass while maintaining structural integrity for shock and vibration resistance.
2Reliability
If wheel-end electric motors are designed with larger components to meet shock and vibration requirements, then robustness is improved, but the package volume increases, consuming valuable wheel-end space
Solution Approach 1:
The motor, planetary gear reducer, and wheel hub are merged into a single integrated assembly. The rotor serves dual functions as both the motor rotor and the hub mounting structure. This merging eliminates the need for separate housings, mounting brackets, and support structures, significantly reducing the overall package volume while maintaining robustness through the integrated structural design.
Solution Approach 2:
The planetary gear set is nested within the motor housing, which is itself integrated with the hub structure. This multi-level nesting arrangement packs multiple functional subsystems into a compact envelope, reducing the overall package volume while maintaining the structural robustness needed for shock and vibration resistance.
3Reliability
If traditional wheel-end electric motor designs are used, then shock and vibration requirements can be met with adequate robustness, but torque density and power density are reduced due to larger, heavier components
Solution Approach 1:
The traditional mechanical support structures, separate bearings, and mounting systems are replaced with a magnetically levitated rotor supported by active magnetic bearings. This substitution eliminates the need for large mechanical support components, reducing the motor envelope and mass while increasing torque density. The active magnetic bearing system provides robust shock and vibration resistance through active control rather than passive mechanical means.
Solution Approach 2:
The motor operates at very high speeds (e.g., 20,000 rpm or higher), fundamentally changing the operating parameters compared to traditional motors. This high-speed operation allows the generation of equivalent torque with significantly reduced component sizes and masses, thereby increasing torque density and power density while the integrated structural design maintains robustness for shock and vibration conditions.
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 modular design enables a smaller package size, lighter weight, better torque and power density, and lower cost, with compatibility for existing vehicle suspensions and brakes, and facilitates easy assembly, repair, and customization.
Implementation Method 1
A lubricant is disposed in the support chamber for supporting the rotor around the stator
Data Source
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AI summary
A lubricant supported electric motor assembly includes an electric motor module, a shifting and first stage module, and a final drive module sequentially operably interconnected with one another for producing drive torque that is ultimately conducted to a wheel of a vehicle. The electric motor module includes a stator and a rotor defining an internal rotor cavity. The shifting and first stage module is disposed within the internal rotor cavity and includes a first planetary gear reducer assembly and an output gear selectively coupleable to said first planetary gear reducer assembly. The final drive module is disposed adjacent the shifting and first stage module and includes a second planetary gear reducer assembly operably coupled with the output gear. A shifting mechanism establishes selective coupling between the first planetary gear assembly and the output gear to transfer adjustable torque from the shifting and first stage module to the final drive device.