Impeller Cover Coating for Minimal Blade Tip Leakage
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Solution Overview
Problem
Fan motors experience efficiency reduction due to excessive leakage flow between the impeller and the impeller cover, caused by inappropriate tip clearance, leading to reduced performance and reliability.
Innovation Solution
A fan motor design featuring a non-metallic coating layer on the inner surface of the impeller cover with varying thicknesses, allowing the blades to grind and adjust the coating during assembly, minimizing the air gap and leakage flow, while maintaining a simple structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the tip clearance is reduced to minimize leakage flow, then the efficiency is improved, but the blades or impeller cover may be worn
Solution Approach 1:
A non-metallic coating layer is applied to the inner circumferential surface of the impeller cover to act as an intermediary between the blade and the impeller cover. This coating layer has lower strength than the blade, allowing it to be worn instead of the blade or impeller cover, thus maintaining minimal tip clearance without causing wear to critical components.
Solution Approach 2:
The non-metallic coating layer is designed as a sacrificial, disposable component with lower strength than the blade. It is intentionally made to wear away over time, protecting the more valuable and critical blade and impeller cover from wear while maintaining the minimal tip clearance needed for efficiency.
2Reliability
If the tip clearance is increased to prevent wear, then the reliability is improved, but the leakage flow becomes excessive and efficiency is reduced
Solution Approach 1:
The non-metallic coating layer serves as a mediator that allows the system to maintain minimal tip clearance for efficiency while protecting against wear. The coating absorbs the wear damage that would otherwise occur between the blade and impeller cover, enabling the system to operate with optimal clearance without compromising reliability.
3Loss of energy
If a non-metallic coating layer is applied to the impeller cover to minimize air gap, then the efficiency is improved, but the device complexity increases
Solution Approach 1:
The non-metallic coating layer is applied as a relatively simple, cost-effective solution that can be applied through conventional coating processes. While it adds a layer to the impeller cover, the complexity increase is minimal compared to the significant efficiency improvement from minimizing the air gap and reducing leakage flow.
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 reduces flow path loss, improves efficiency, and compensates for assembly errors and increased thrust by maintaining a minimal air gap, enhancing the reliability of the fan motor.
Implementation Method 1
the blade grinds a part of the non-metallic coating layer to have a second thickness thinner than the first thickness during rotation of the impeller
Data Source
AI summary
A fan motor includes: a motor housing; a rotating shaft; a rotor; a stator disposed outside the rotor; an impeller having at least one blade and a hub; and an impeller cover surrounding an outer circumference of the impeller and defining an air suction inlet. The impeller cover includes: a shroud having an inner diameter that expands in an air flow direction; and a non-metallic coating layer coated on an inner circumferential surface of the shroud and having a lower strength than the blade. The non-metallic coating layer includes: a first area having a first thickness; a second area having a second thickness thinner than the first thickness and defining a stepped portion with the first area, thereby minimizing leakage flow caused by the pressure difference from a pressure-side surface to a suction-side surface of the blade to reduce flow path loss and improving efficiency of the fan motor.