Reverse Fan Motor Bearing Preload for Cooling and Vibration Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing fan motors face issues with reduced cooling performance, shortened bearing lifespan, instability due to moments generated by the impeller, and increased vibration and noise due to gaps and thrust application on bearings, particularly in reverse fan motors.
Innovation Solution
A reverse fan motor design with a motor positioned upstream of the impeller, using a spring to apply preload to the first bearing and a stopper to restrict the second bearing, along with a holder and O-ring to maintain constant preload and prevent bearing movement, minimizing moments and gaps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the fan rotates at high speed (10,000 rpm to 140,000 rpm) to increase suction force, then cleaning performance is improved, but the lifespan of the bearing is reduced
Solution Approach 1:
The patent applies preload to the bearing before operation to eliminate gaps between balls and raceway in advance. This preliminary action prevents vibration and noise that would otherwise occur during high-speed rotation, thereby extending bearing lifespan while maintaining high suction force capability
Solution Approach 2:
The patent changes the physical state of the bearing by applying a predetermined load (preload) to maintain constant contact between balls and raceway. This parameter change ensures stable bearing operation at high speeds without gap-induced vibration, resolving the contradiction between productivity and durability
2Stability of the object's composition
If preload is applied to the second bearing to eliminate gaps, then bearing stability is improved, but the first bearing becomes overloaded and lifespan is shortened
Solution Approach 1:
The patent applies preload specifically to the second bearing (further from impeller) rather than the first bearing. This parameter change in load distribution allows the first bearing to handle thrust loads without being overloaded, while the second bearing maintains stability and eliminates gaps, resolving the contradiction between stability and lifespan
3Stability of the object's composition
If thrust is applied to the second bearing, then bearing stability is improved, but a gap increases between balls and raceway causing vibration and slipping
Solution Approach 1:
The patent applies preload to the second bearing before operation to maintain constant contact between balls and raceway. This preliminary action prevents gap formation during thrust loading, eliminating vibration and slipping that would otherwise occur, thus resolving the contradiction between stability and harmful vibrations
4Ease of manufacture
If the impeller is located upstream of the motor (forward fan motor), then structural design is simplified, but cooling performance is reduced due to air temperature rise
Solution Approach 1:
The patent inverts the conventional arrangement by placing the impeller downstream of the motor instead of upstream. This inversion allows cooler air to first pass through the motor for cooling before reaching the impeller, resolving the contradiction between ease of manufacture and cooling performance by prioritizing thermal management
5Temperature
If the impeller is located downstream of the motor (reverse fan motor), then cooling performance is improved, but the structural design must be adapted for bearing preload application
Solution Approach 1:
The patent applies preload to the second bearing as a preliminary structural adaptation that enables stable operation with the reversed configuration. This preliminary structural design allows the impeller to be positioned downstream for improved cooling while maintaining proper bearing function, resolving the contradiction between cooling performance and device complexity
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
Improves cooling performance, extends bearing lifespan, and reduces vibrations and noise by stabilizing the bearings, and enhances the stability and durability of the bearings during high-speed operation.
Implementation Method 1
a spring configured to apply preload to the first bearing
Implementation Method 2
an O-ring mounted on an outer circumferential surface of the spring outer wall, and configured to be movably in contact with an inner circumferential surface of the first bearing housing in the thrust direction
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A fan motor is disclosed. This fan motor is a reverse fan motor in which an impeller is arranged at a downstream side of the motor with respect to an air flow direction. Accordingly, the cooling performance of the motor is improved. The fan motor includes a spring that applies a preload to a bearing. Accordingly, it is possible to extend the lifespan of the bearing by removing the gap between the balls and the raceway of the bearing. One of the two bearings is close to the impeller. The bearing close to the impeller is a load bearing. The fan motor includes a stopper arranged inside the motor housing to surround one surface of the load bearing. Accordingly, the stopper can limit the movement of the load bearing in the thrust direction when the load bearing receives thrust during operation.