Hybrid Vehicle Transaxle Stator Mounting for NVH Reduction
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Solution Overview
Problem
Hybrid and electric vehicle transmissions with electric machine stators mounted in a cantilevered fashion experience undesirable noise, vibration, and harshness (NVH) issues due to insufficient stiffness, leading to reduced efficiency and fuel economy.
Innovation Solution
A vehicle transaxle design that secures both longitudinal ends of the electric machine stator to the housing using a combination of fasteners and mounting plates, increasing stiffness while avoiding additional stress on the stator core, thereby reducing NVH issues and maintaining efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the stator is mounted in a cantilevered fashion, then the device complexity is reduced, but the stiffness is insufficient leading to NVH issues
Solution Approach 1:
The mounting structure is segmented into two independent mounting locations: one at each longitudinal end of the stator. This divides the single cantilevered mounting point into multiple support points, providing stiffness at both ends while maintaining modular assembly simplicity.
Solution Approach 2:
The mounting approach transitions from single-point cantilevered mounting to multi-point distributed mounting along the longitudinal dimension. By adding support at both ends rather than one end, the structure gains stiffness in the longitudinal direction without significantly increasing overall complexity.
2Strength
If additional fasteners are added to secure both ends of the stator, then the stiffness is improved, but the device complexity increases
Solution Approach 1:
The housing structure is designed with integrated mounting features that serve multiple functions: the first and second locations both provide stator support, alignment, and stress distribution. This multi-functional design achieves enhanced stiffness without proportionally increasing component count.
Solution Approach 2:
Different mounting characteristics are applied at different longitudinal locations of the stator. Each mounting location is optimized for its specific position, providing localized stiffness where needed while maintaining overall structural efficiency and avoiding uniform over-engineering throughout the entire assembly.
Data Source
AI summary
A vehicle transaxle includes a housing, an electric machine stator, a plurality of mounting plates, and a first set of fasteners. The housing has internal walls that define a cavity and an access opening to the cavity. The electric machine stator is disposed within the cavity between a first of the internal walls and the opening. The plurality of mounting plates secures a first longitudinal end of the stator to the housing proximate the opening. Each fastener of the first set of fasteners extends through one of the mounting plates, through the stator, and engages the first of the internal walls to secure a second longitudinal end of the stator to the first of the internal walls.