Elastomeric Spacer for Stator Retention in High-Speed Motors
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Solution Overview
Problem
Existing electrically-assisted turbochargers face challenges in achieving lower assembly costs and efficient heat transfer due to the need for high-speed, low-torque electric motors, which often require interference fits, adhesives, or additional parts to prevent stator rotation within the motor housing.
Innovation Solution
An electric motor design featuring a stator with a clearance fit within the housing, utilizing an elastomeric spacer to restrict stator movement and promote conductive heat transfer, eliminating the need for interference fits and adhesives, and allowing for easier assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a clearance fit is used between the stator and motor housing, then assembly cost is reduced and assembly is easier, but the stator may rotate inside the housing and heat transfer efficiency decreases
Solution Approach 1:
A circumferential groove is introduced as an intermediary feature between the stator and motor housing. This groove receives an elastomeric spacer that acts as a mediator to prevent stator rotation while maintaining the clearance fit. The spacer fills the radial clearance and provides frictional resistance against rotational movement without requiring interference fit or additional fastening parts.
Solution Approach 2:
An elastomeric spacer (flexible element) is used to fill the circumferential groove and provide rotational constraint. The elastomeric material deforms elastically to accommodate the clearance fit while generating sufficient friction force to prevent stator rotation. This flexible element maintains thermal contact between stator and housing while eliminating the need for rigid interference fits or adhesive bonds.
2Ease of manufacture
If a clearance fit is used between the stator and motor housing, then assembly is easier without additional parts, but conductive heat transfer between stator and housing is reduced
Solution Approach 1:
The elastomeric spacer serves as a thermal intermediary that maintains conductive heat transfer pathways. While the spacer itself is not a perfect thermal conductor, it maintains continuous physical contact between the stator outer periphery and the motor housing through the circumferential groove interface, preserving thermal coupling without requiring interference fit or thermal adhesives.
Solution Approach 2:
The elastomeric spacer, though flexible, maintains sufficient thermal contact pressure through elastic deformation to enable conductive heat transfer. The material's compliance allows it to conform to surface irregularities and maintain consistent thermal contact between the stator and housing across the circumferential interface, preventing thermal isolation while enabling easy assembly.
3Reliability
If adhesive or mechanical fastener is used to retain the stator, then stator positioning is secure, but assembly cost increases and assembly complexity increases
Solution Approach 1:
The elastomeric spacer in the circumferential groove acts as a mediator that provides rotational constraint through friction alone, eliminating the need for adhesive or mechanical fasteners. This single elastomeric element simultaneously prevents stator rotation and maintains thermal contact, reducing assembly complexity to a simple snap-fit operation without multiple parts or bonding processes.
Solution Approach 2:
The elastomeric spacer provides self-retaining functionality through elastic deformation and friction. When the stator is inserted into the motor housing, the spacer compresses elastically within the circumferential groove and generates sufficient friction force to prevent rotation autonomously, without requiring external adhesives, fasteners, or complex assembly procedures. The system self-secures through the elastomeric property.
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 design reduces assembly costs while ensuring the stator is securely positioned for efficient heat transfer and operation, maintaining the required high-speed performance without additional fixation methods.
Implementation Method 1
an elastomeric spacer connected on an extreme end of the boss compliantly filling the axial clearance between the stator and the boss positioning the stator in an axial direction and restricting movement of the stator in an angular direction within the housing opening
Implementation Method 2
having a fit close enough to promote conductive heat transfer between the stator and the motor housing
Data Source
AI summary
An electromechanical is provided which includes an electromagnetic rotor, a housing with an interior opening with a stop, a first bearing mount for supporting a first bearing rotatably mounting the rotor in the housing, a cover connected with the housing having a boss having an interior providing a second bearing mount supporting a second bearing rotatably mounting the rotor in the housing, a stator having a clearance fit within the housing interior opening, the stator being axially limited in a direction toward such first bearing mount by the housing stop, the stator having an axial clearance in a direction toward the cover boss, and an elastomeric spacer connected on an extreme end of the boss compliantly filling the axial clearance between the stator and the boss positioning the stator in an axial direction and restricting movement of the stator in an angular direction within the housing opening.