Electric Axle Layout With Lateral Motor and Unequal Axle Shafts
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Solution Overview
Problem
Vehicle platform electrification presents challenges such as space constraints and packaging issues for electric drive units due to the carry-over of internal combustion engine components, limited space under the engine, and constrained wheel centerline options in hybrid powertrains.
Innovation Solution
An electric axle assembly with a planetary differential and unequal-length axle shafts, where the electric machine is positioned laterally between drive wheel shafts, and a gear reduction system that allows for compact packaging and reduced interference with surrounding components, including a lubricant reservoir positioned below the electric machine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional electric motor placement is used in hybrid powertrains, then the electric motor can be positioned in conventional locations, but space constraints from engine componentry and vehicle frame limit viable placement options
Solution Approach 1:
The patent repositions the electric motor laterally between the drive wheel shafts rather than placing it in conventional longitudinal positions. This lateral placement in the transverse dimension creates a compact packaging arrangement that fits within the limited space under the engine component while maintaining all necessary functional connections.
Solution Approach 2:
The electric motor, planetary differential, and axle shafts are arranged in a nested configuration where the motor is positioned laterally between the drive wheel shafts, the planetary differential is integrated with the motor output, and the axle shafts extend from the differential. This nested arrangement maximizes space utilization within the constrained volume under the engine component.
2Volume of stationary object
If compact electric axle packaging is achieved, then space constraints on surrounding vehicle components are reduced, but the electric machine and axle shafts must be positioned closer together
Solution Approach 1:
By positioning the electric motor laterally between the drive wheel shafts rather than in line with them, the patent achieves compact packaging in the longitudinal dimension while maintaining adequate spacing in the lateral dimension for component connections and maintenance access.
Solution Approach 2:
The second axle shaft is made longer than the first axle shaft to accommodate the lateral positioning of the electric motor. This asymmetric configuration allows the motor to be positioned closer to one side while still providing adequate clearance and connection points for both drive wheel shafts.
3Volume of moving object
If the second axle shaft is made longer to accommodate lateral motor positioning, then the electric machine and second axle shaft can be space efficiently packaged, but the axle shaft length becomes asymmetric
Solution Approach 1:
The patent deliberately employs asymmetric axle shaft lengths to achieve compact packaging. The longer second axle shaft extends further to accommodate the lateral positioning of the electric motor, while the shorter first axle shaft provides sufficient length for its side. This asymmetric design optimizes the overall volume efficiency of the electric axle assembly.
Solution Approach 2:
Each axle shaft is given different lengths appropriate to its specific functional requirements and spatial constraints. The longer second axle shaft compensates for the lateral motor positioning on one side, while the shorter first axle shaft is sufficient for the other side, optimizing the local quality of each component.
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 electric axle assembly achieves space-efficient packaging while meeting high performance demands and reducing interference with vehicle components, allowing for integration into hybrid powertrains without the need to decrease the size of the lubricant reservoir.
Implementation Method 1
an electric machine rotationally coupled to a planetary differential
Implementation Method 2
a gear reduction may be used to rotationally couple the electric machine and the planetary differential
Data Source
AI summary
Systems and method for an electric axle assembly. The electric axle assembly includes, in one example, an electric machine rotationally coupled to a planetary differential and a first and second axle shaft directly rotationally coupled to the planetary differential. In the axle assembly, the second axle shaft is longer than the first axle shaft and the electric machine is positioned laterally between a first drive wheel shaft and a second drive wheel shaft that are rotationally coupled to the first axle shaft and the second axle shaft.