Stator Retainer Caps for Electric Vehicle Motor NVH Control
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Solution Overview
Problem
Existing stator mounting designs for electric vehicle motors face challenges in noise, vibration, and harshness (NVH) performance due to stator twisting, and solutions like shrink fitting compromise motor efficiency and range.
Innovation Solution
A retainer system comprising caps with outer rims and washer portions attached to the motor housing, where bolts clamp the caps to the stator, allowing for axial flexibility to accommodate thermal expansion and misalignment, preventing NVH issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If bolts are used to directly attach the stator to the motor housing, then motor range is maximized, but NVH performance deteriorates due to stator twisting
Solution Approach 1:
The retainer system segments the stator support function into multiple components: the retainer body provides structural support while the flexible washer portion provides NVH isolation. This segmentation allows the rigid support needed for efficiency and the flexible damping needed for NVH performance to coexist.
Solution Approach 2:
The retainer utilizes thermal expansion parameter changes by designing the flexible washer portion to expand and contract with temperature variations. This allows the retainer to maintain proper clamp load across operating temperatures while accommodating thermal growth of the motor housing and stator.
2Object-affected harmful factors
If the stator is shrink fit to the housing to improve NVH performance, then NVH performance improves, but motor efficiency and range are reduced
Solution Approach 1:
The retainer system separates the NVH isolation function (flexible washer portion) from the structural support function (retainer body), allowing optimal design for each function independently while maintaining both performance requirements simultaneously.
Solution Approach 2:
The retainer employs a composite structure combining rigid material for the retainer body and flexible material for the washer portion. This composite approach enables the system to provide both the structural integrity needed for motor efficiency and the vibration damping needed for NVH performance.
3Adaptability or versatility
If the retainer system accommodates thermal expansion with flexible washer portion, then thermal compatibility improves, but device complexity increases
Solution Approach 1:
The flexible washer portion acts as an intermediary element between the rigid retainer body and the stator, absorbing thermal expansion differences and misalignment variations. This simple intermediary component provides thermal compatibility without requiring complex adjustment mechanisms.
Solution Approach 2:
The retainer system utilizes controlled flexibility parameter changes in the washer portion to adapt to thermal expansion and misalignment variations. This passive parameter adaptation achieves thermal compatibility without active control systems or complex mechanisms.
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 retainer system effectively reduces NVH by maintaining stator alignment, accommodating thermal expansion, and preventing tilting, thereby enhancing motor efficiency and range while maintaining good NVH performance.
Implementation Method 1
the washer portion flexes axially in response to thermal expansion and contraction of the motor housing
Implementation Method 2
The heads of the bolts clamp the cap to the stator to frictionally retain one end of the stator
Data Source
AI summary
A motor for an electric vehicle includes a motor housing for receiving a stator. A plurality of caps each have an outer rim and a washer portion defining a bolt receiving opening. The outer rim of each of the caps is press-fit into the receptacles in the motor housing. The caps are each attached to the stator by one of the bolts. The heads of the bolts clamp the cap to the stator to retain one end of the stator. The outer rim holds the cap in the motor housing while the washer portion flexes axially in response to thermal expansion and contraction of the motor housing. A method is disclosed for assembling the stator into the motor housing.