Fan Impeller Shroud Coating for Minimal Tip Clearance
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Solution Overview
Problem
Existing fans face inefficiencies due to excessive leakage flow between the impeller and the impeller cover, which can be attributed to improper tip clearance, leading to reduced performance and reliability.
Innovation Solution
A fan design featuring a non-metallic coating layer on the impeller cover with varying thicknesses, where the blade grinds the coating during assembly to minimize clearance, utilizing materials like PEEK or Teflon, ensuring a self-sacrificial layer that maintains a minimal air gap and compensates for assembly tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the tip clearance is reduced to minimize leakage flow, then fan efficiency is improved, but the risk of blade or impeller cover wear increases
Solution Approach 1:
The patent introduces a non-metallic coating layer as an intermediary between the blade and the impeller cover. This coating layer has lower strength than the blade, allowing it to be selectively worn away while protecting the blade from direct contact and wear with the impeller cover. The coating acts as a sacrificial element that maintains minimal clearance benefits while preventing damage to critical components.
Solution Approach 2:
The non-metallic coating layer is designed as a disposable, sacrificial element that is intentionally allowed to wear away over time. By using a lower-strength material for the coating compared to the blade, the system accepts that the coating will be consumed during operation, but this protects the more valuable blade and maintains efficient clearance characteristics throughout the coating's service life.
2Productivity
If a non-metallic coating layer is applied to the impeller cover, then leakage flow is minimized and fan efficiency is enhanced, but the device complexity increases
Solution Approach 1:
The non-metallic coating layer is applied selectively only to the inner circumferential surface of the impeller cover where it contacts the blade tips. This localized application provides the efficiency benefits of minimal clearance only where needed, while leaving the rest of the impeller cover structure simple and unchanged. The coating is concentrated in the critical clearance zone rather than being applied throughout the entire component.
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
This design reduces flow path losses, enhances fan efficiency, and improves reliability by minimizing leakage flow and accommodating variations in thrust and assembly errors.
Implementation Method 1
the blade grinds a part of the non-metallic coating layer to have a second thickness thinner than the first thickness
Data Source
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AI summary
A fan motor according to an embodiment includes a motor housing; a rotating shaft; a rotor mounted on the rotating shaft; a stator disposed within the motor housing to surround the rotor; an impeller having at least one blade formed on an outer surface of a hub connected to the rotating shaft; an impeller cover configured to surround an outer circumference of the impeller and having an air suction inlet formed therein, wherein the impeller cover includes a shroud with an inner diameter 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 that of 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 having 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.