Concentric Axle Drive Assembly for Compact High-Voltage Packaging
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Solution Overview
Problem
Existing axle drive assemblies have undesirable packaging volumes and inefficiencies due to parallel, offset drive shafts, which hinder power and torque density.
Innovation Solution
An integrated axle drive assembly with concentric drive shafts and a single housing that includes an inverter, electric machine, reducer, differential, and brake assemblies, where the drive shafts share a common axis, allowing for reduced packaging volume and increased efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If parallel offset drive shafts are used in traditional axle drive assemblies, then the assembly can accommodate conventional component layouts, but the packaging volume increases and power/torque density decreases
Solution Approach 1:
The patent implements nesting by placing the first drive shaft inside the hollow second drive shaft, creating a concentric configuration where one component is embedded within another. This nested arrangement allows both drive shafts to share the same spatial envelope, dramatically reducing the overall packaging volume of the axle drive assembly while maintaining the necessary functional separation between the shafts through appropriate spacing elements or clearances.
Solution Approach 2:
The invention transitions from a two-dimensional parallel shaft arrangement to a three-dimensional concentric configuration. By utilizing the radial dimension and arranging shafts in a nested cylindrical layout rather than parallel offset positions, the design exploits spatial efficiency in the radial direction, reducing the lateral footprint and overall volume occupied by the drive assembly.
2Volume of moving object
If traditional separate housing designs are used for brake assemblies, then brake maintenance and assembly are simplified, but the overall packaging volume increases
Solution Approach 1:
The patent merges previously separate housing components into a single integrated housing structure that accommodates the electric machine, reducer, differential, and brake assemblies together. This consolidation eliminates the need for multiple separate housings and their associated mounting flanges and fasteners, reducing the overall packaging volume while the modular internal arrangement of components maintains ease of assembly and maintenance access.
3Power
If concentric drive shafts are implemented, then power and torque density increase, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies local quality by providing spacing elements or clearances at specific locations between the nested drive shafts to maintain precise concentric alignment. Rather than requiring uniform precision throughout the entire shaft length, localized spacing features are positioned at critical points to ensure proper alignment and rotational clearance, making the manufacturing precision requirements more manageable while still achieving the power density benefits of concentric configuration.
Data Source
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AI summary
The present invention relates to an integrated axle drive assembly (10) and a method for operating an integrated axle drive assembly (10). The integrated axle drive assembly (10) includes a hollow shaft (16), at least one drive shaft (12,14) extending through and concentric with the hollow shaft (16), an e-machine (22), the hollow shaft (16) extending through and connected to the e-machine (22), a reducer (26) located next to the e-machine (22), the hollow shaft (16) engaged with the reducer (26), and an inverter (28) located next to the e-machine (22), the hollow shaft (16) extending through the inverter (28). The integrated axle drive assembly includes at least one brake assembly (30,34) connected to the drive shaft (12,14) and operable for applying a brake force to the at least one drive shaft (12,14). The hollow shaft (16), the e-machine (22), the reducer (26), the inverter (28) and the at least one brake assembly (30,34) are disposed in a housing (44), and the at least one drive shaft (12,14) at least partially extends through and protrudes out of the housing (44). The e-machine (22) rotates the hollow shaft (16) such that the hollow shaft (16) drives the reducer (26) and the at least one drive shaft (12,14).