BLDC Motor Bearing Structure Without Spring Preload
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Solution Overview
Problem
The service life of high-speed BLDC motors is shortened due to nonuniform stress on steel balls of bearings caused by machining errors of end faces when a spring is assembled between two bearing assemblies, leading to fatigue failure and abrasion of the bearing track.
Innovation Solution
A stable bearing structure is implemented using a shaft sleeve made of metal, with adhesives between bearing inner rings and the rotating shaft, and a boss providing support to the bearing member, ensuring uniform stress distribution and eliminating the need for a spring, while ventilation grooves in the housing facilitate self-cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a spring is mounted between two bearing assemblies to apply pre-tightening force, then the bearing structure can maintain initial contact force, but machining errors of end faces cause bearing deviation and nonuniform stress on steel balls
Solution Approach 1:
The patent removes the spring component from the bearing assembly, eliminating the source of deviation caused by machining errors of spring end faces. The bearing assembly directly contacts the rotor assembly without intermediary spring components, thereby eliminating the transmission of machining errors to the bearing positioning.
Solution Approach 2:
The patent segments the bearing assembly into independent bearing units that are directly mounted on the rotor assembly. Each bearing is positioned independently with precise control over its location, allowing the pre-tightening force to be applied uniformly without the cumulative effect of machining errors from spring components.
2Force
If a spring is used to apply pre-tightening force to bearing outer rings, then initial contact force is maintained, but nonuniform stress on steel balls causes fatigue failure after long-term operation
Solution Approach 1:
The spring component is completely removed from the bearing assembly. The pre-tightening force is now applied directly through the bearing assembly structure itself, eliminating the nonuniform stress distribution that occurred with spring-mediated force application. This direct force transmission ensures uniform stress on steel balls throughout operation.
Solution Approach 2:
The bearing assembly is pre-configured with the correct pre-tightening force applied during assembly, without requiring spring components to maintain this force during operation. The structural design of the bearing assembly itself provides the necessary pre-tightening, ensuring uniform stress distribution from the start of operation.
3Force
If a spring is assembled between bearing assemblies, then pre-tightening force is applied, but bearing deviation occurs due to machining errors, causing abrasion of bearing track
Solution Approach 1:
The spring component is removed from the assembly, eliminating the complex multi-step process of assembling spring components between bearing assemblies. The simplified direct mounting structure reduces the number of assembly steps and eliminates the need to accommodate spring end face machining variations.
Solution Approach 2:
The bearing assembly is segmented into modular units that can be independently mounted on the rotor assembly. This segmentation allows for straightforward installation without the need to assemble spring components, reducing mounting complexity while maintaining the necessary pre-tightening force through direct structural support.
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 prolongs the service life of the BLDC motor by preventing fatigue failure and abrasion, ensuring convenient mounting and reducing operating temperature through uniform stress distribution and self-cooling.
Implementation Method 1
adhesives are provided on contact surfaces of the first bearing inner ring and the second bearing inner ring with the rotating shaft
Implementation Method 2
two end faces of the shaft sleeve are in contact with end faces of the first bearing inner ring and the second bearing inner ring respectively
Implementation Method 3
an end face of the housing is provided with ventilation grooves
Data Source
AI summary
Disclosed is a high-speed BLDC motor with a stable bearing structure, including a stator assembly, a rotor assembly, a rotating shaft and a bearing member, where the bearing member includes a first bearing and a second bearing, the first bearing includes a first bearing inner ring and a first bearing outer ring, the second bearing includes a second bearing inner ring and a second bearing outer ring, two end faces of a shaft sleeve are in contact with end faces of the first bearing inner ring and the second bearing inner ring respectively, and adhesives are provided on contact surfaces of the first bearing inner ring and the second bearing inner ring with the rotating shaft.