Dual-Pilot Input Gear Assembly for Coaxial Alignment Stability
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Solution Overview
Problem
Conventional input gear assemblies in electric vehicle powertrains experience misalignment due to a single pilot region on the input shaft, leading to performance degradation and potential reliability issues over time.
Innovation Solution
A dual-pilot region arrangement is implemented, where the input gear is coupled to the input shaft via two spaced-apart pilot regions, one on the shaft and another on the inner bearing raceway, ensuring proper alignment and preventing tilting, thus enhancing the assembly's performance and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single pilot region is used on the input shaft, then the structure is simpler, but misalignment and tilting occur leading to performance degradation
Solution Approach 1:
The single pilot region is segmented into two separate pilot regions: one on the input shaft and another on the inner bearing raceway. This segmentation allows each pilot region to independently support one end of the input gear, preventing tilting and maintaining coaxial alignment between the input shaft, input gear, and bearing axes throughout operation.
2Reliability
If a dual-pilot region arrangement is implemented, then alignment stability is improved, but the device complexity increases
Solution Approach 1:
The inner bearing raceway acts as an intermediary component that carries a pilot region. This allows the bearing assembly to participate in the alignment function, distributing the support load and preventing gear tilting without requiring complex modifications to the input shaft alone. The intermediary bearing raceway seamlessly integrates the second pilot region into the existing bearing structure.
3Manufacturing precision
If pilot regions are spaced apart on the shaft, then tilting is prevented, but manufacturing complexity increases
Solution Approach 1:
The inner bearing raceway is designed to serve multiple functions: it supports the input gear via its pilot region, provides bearing functionality for the input shaft, and maintains axial positioning. This multi-functionality allows the second pilot region to be implemented without adding separate dedicated components, simplifying the overall manufacturing process despite the increased alignment precision requirements.
Data Source
AI summary
An input gear assembly in which the input gear is coupled to the input shaft via a pair of spaced-apart pilot regions of the input shaft. One of the pilot regions is disposed adjacent to one of the bearings used, with the pilot region formed in or on the input shaft itself and engaging a corresponding internal surface of the input gear. Another of the pilot regions is formed in the inner bearing raceway of another of the bearings used, with the pilot region formed as an elongate portion of the inner bearing raceway of the input shaft and engaging another corresponding internal surface of the input gear. For manufacturing simplicity, this additional pilot region and the remainder of the elongate inner bearing raceway have the same material properties, surface treatment, straightness, and cylindricity. This arrangement prevents tilting of the input gear with respect to the input shaft and bearing shaft, thereby enhancing performance.