Hybrid Vehicle Stator Mounting Bracket NVH Reduction
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Solution Overview
Problem
Conventional mounting arrangements for electric machine stators in vehicle transmissions often result in undesirable noise, vibration, and harshness (NVH) issues due to insufficient stiffness and potential stress on the stator core, leading to reduced efficiency and propulsion range in hybrid and electric vehicles.
Innovation Solution
A mounting arrangement that secures the electric machine stator between a housing and a mounting bracket with an elastic outer portion, which engages the internal side wall and provides an interference-fit, supporting both longitudinal ends of the stator to increase stiffness while minimizing additional stress, using a metallic inner ring and elastomer outer ring to absorb vibrations and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional mounting arrangement is used for the electric machine stator, then the installation is simple, but the stiffness is insufficient and NVH issues occur
Solution Approach 1:
The mounting bracket uses a composite structure combining a rigid metallic inner ring for structural strength and stiffness with a compliant elastomer outer ring for vibration absorption. This composite material approach resolves the contradiction by providing both the required mounting stiffness and NVH performance without excessive complexity
Solution Approach 2:
Different portions of the mounting bracket have different material properties: the inner ring uses metal for rigidity and load-bearing, while the outer ring uses elastomer for compliance and vibration damping. This local differentiation of material quality allows the single component to satisfy multiple conflicting requirements
2Strength
If the stator is secured with multiple fasteners, then the mounting stiffness is improved, but the stress on the stator core increases
Solution Approach 1:
The mounting bracket acts as an intermediary component between the stator and the housing. It distributes the mounting loads across a larger area and provides compliance that reduces stress concentration on the stator core, while still maintaining sufficient mounting stiffness through its rigid inner ring structure
Solution Approach 2:
The elastomer material properties (viscoelasticity, damping coefficient) are selected to optimize the balance between providing sufficient mounting stiffness and reducing stress transmission to the stator core. The material parameters are chosen to absorb vibrations and reduce harmful stresses
3Object-affected harmful factors
If a rigid mounting structure is used, then the NVH performance deteriorates, but the mounting stiffness is sufficient
Solution Approach 1:
The outer ring of the mounting bracket uses an elastomeric flexible material that can deform to absorb vibrations and reduce noise transmission. This flexible portion surrounds the rigid inner ring, combining the benefits of both rigid and flexible structures in a single 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
This configuration effectively reduces NVH issues and maintains stator core efficiency by providing enhanced support and stress distribution, improving the vehicle's propulsion range and fuel economy.
Implementation Method 1
provides an interference-fit
Implementation Method 2
to absorb vibrations and noise
Implementation Method 3
providing enhanced support and stress distribution
Implementation Method 4
The fasteners extend through the mounting bracket, through the stator, and engage the second internal wall to secure the stator to the housing
Data Source
AI summary
A vehicle transmission includes a housing, an electric machine, a bracket, and a plurality of fasteners. The housing has internal rear and internal side walls that define a cavity. The electric machine stator and the bracket are disposed within the cavity. The bracket has a metallic inner ring and an elastomer outer ring. The elastomer outer ring engages the internal side wall. The electric machine stator is disposed between the bracket and the internal rear wall. The plurality of fasteners extends through the metallic inner ring, through the stator, and engages the rear internal wall to secure the stator to the housing.