Electric Fan Ball Bearing Corrosion Prevention via Equipotentiality
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Solution Overview
Problem
Existing electric fans with insulating resin fan housings face challenges in preventing electric corrosion of ball bearings due to unabsorbed electromagnetic noise, leading to potential differences between the outer and inner races of the ball bearing.
Innovation Solution
An electric fan design that includes a metal electromagnetic noise guard grounded to the bearing holder, connected via an electrically conducting path, which reduces the potential difference between the outer and inner races of the ball bearing, thereby preventing electric corrosion. This design integrates the electromagnetic noise guard and conducting path within the fan housing, ensuring effective electrical conduction without compromising air suction or discharge functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a grounded electromagnetic noise guard is provided in the fan casing, then electromagnetic noise is prevented from entering the motor, but electric corrosion still occurs in the ball bearing due to potential difference between inner and outer races
Solution Approach 1:
The patent applies equipotentiality by electrically connecting the bearing holder to the electromagnetic noise guard through a conducting path. This connection equalizes the electrical potential between the inner race (connected to rotary shaft) and outer race (connected to bearing holder), eliminating the potential difference that causes electric corrosion. The bearing holder and electromagnetic noise guard are both maintained at the same ground potential, preventing electrolytic corrosion of the ball bearing.
2Object-affected harmful factors
If the fan casing is made of insulating resin, then electromagnetic noise is reduced, but the electromagnetic noise guard cannot be sufficiently grounded to prevent ball bearing corrosion
Solution Approach 1:
The patent introduces an intermediary conducting path that bridges the insulating fan casing to electrically connect the electromagnetic noise guard with the bearing holder. This intermediary element (conducting path) overcomes the insulation barrier, allowing electrical potential equalization between ground-referenced components without compromising the insulating properties of the fan casing for electromagnetic noise reduction.
3Reliability
If the electromagnetic noise guard and bearing holder are electrically connected, then the potential difference between ball bearing races is reduced, but the structure becomes more complex
Solution Approach 1:
The patent merges the grounding function into the existing electromagnetic noise guard structure by electrically connecting it to the bearing holder. Rather than adding a separate grounding mechanism, the solution combines the noise guard's electromagnetic shielding function with the grounding function, using the same structural element (bearing holder) to provide both mechanical support and electrical connection to ground.
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 effectively reduces the potential difference between the outer and inner races of the ball bearing, preventing electric corrosion and maintaining the fan's operational efficiency even in environments with electromagnetic noise.
Implementation Method 1
The electromagnetic noise guard is electrically connected to the bearing holder and electrically grounded
Implementation Method 2
a potential difference may be produced between the outer and inner races of the ball bearing by electromagnetic noise
Data Source
AI summary
A fan casing, webs, and a motor casing are integrally formed of a resin material by injection molding to configure a fan housing. An electrically grounded electromagnetic noise guard and a bearing holder to which an outer race of a ball bearing are electrically connected by an electrically-conducting path member provided in the fan casing by means of insert molding. Thus, the ball bearing may sufficiently be prevented from suffering electric corrosion in an electric fan of which a fan housing is made of an insulating resin.