Electric Motor Bearing Preload Assembly With Retained Spring
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Solution Overview
Problem
The challenge of ensuring proper assembly and preventing unintentional detachment of prestressing springs in electric machines, particularly in hybrid or fully electrically driven motor vehicles, where the assembly process is complex and difficult to monitor.
Innovation Solution
A spring element is used to axially prestress a rolling bearing in the electric machine, secured by a form fit between the spring element and the bearing seats, ensuring it remains in a defined position during assembly, thereby preventing unintentional removal and ensuring correct assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a prestressing spring is used to reduce internal play in rolling bearings, then the reliability of the bearing is improved, but the spring element can become detached during assembly and handling
Solution Approach 1:
The spring element is nested within the bearing assembly structure, specifically positioned in a recess of the bearing seat and retained by a retaining ring. This nesting approach ensures the spring remains integrated with the bearing components throughout assembly and operation, preventing detachment while maintaining the reliability benefits of prestressing.
Solution Approach 2:
The spring element is pre-installed in the bearing seat recess before the rolling bearing is mounted. This preliminary positioning, combined with the retaining ring, ensures the spring is securely in place before handling or overhead assembly operations occur, preventing detachment during subsequent assembly steps.
2Manufacturing precision
If individual bearing components are assembled with prestressing springs, then the radial play is reduced, but it becomes practically impossible to check correct positioning during assembly
Solution Approach 1:
The patent employs visual indicators such as colored markings or contrast-colored components on the spring element and bearing assembly. These visual cues enable assembly workers to quickly verify correct spring positioning and bearing installation without complex measurement tools, solving the verification difficulty while maintaining precision.
3Productivity
If overhead assembly is performed with prestressing springs, then production efficiency is improved, but the spring element is at risk of unintentional removal
Solution Approach 1:
The spring element is nested within the bearing seat recess and secured by a retaining ring, creating a compact integrated assembly. This nested structure prevents the spring from becoming dislodged during overhead handling and assembly operations, enabling safe and efficient overhead production methods.
Solution Approach 2:
The spring element is pre-positioned and secured in the bearing seat before overhead assembly operations begin. This preliminary securing prevents unintentional removal during the overhead assembly process, maintaining both productivity and reliability.
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 solution enhances assembly safety and ease by maintaining the spring element's position relative to the bearing seats, allowing for overhead assembly and preventing misassembly, thus optimizing the assembly process.
Implementation Method 1
an axial load can be applied to a bearing ring, which is usually effected by means of spring force. This is referred to as prestress and ensures constant contact between the rolling bodies and the bearing rings and reduces any play that may occur between components.
Data Source
AI summary
An electric machine for use within the powertrain of a hybrid or fully electric motor vehicle including a stator and a rotor which is separated from the stator by an air gap, said stator and rotor being received in an engine housing. The rotor is rotatably mounted relative to the stator by means of two axially spaced rolling bearings, and at least one of the rolling bearings is axially biased by a spring element which is supported against the motor housing in the axial direction and lies against the rolling bearing. The biased rolling bearing has an inner ring and an outer ring, between which a plurality of rolling bodies are received in a rollable manner, the inner ring is rotationally fixed to the rotor via a first bearing seat, and the outer ring is rotationally fixed to the engine housing via a second bearing seat. The spring element is arranged on the first bearing seat and/or second bearing seat so as to be secured in the axial direction in a form-fitting manner.