Variable Pitch Axial Fan with Tip Magnetic Drive
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Solution Overview
Problem
Ducted axial flow fans face inefficiencies and high power consumption due to aerodynamic drag, turbulence, and noise, particularly at the rotor tips, which increases manufacturing costs and reduces performance across a wide range of pressures and flow rates, necessitating a design that enhances efficiency and reduces operational costs.
Innovation Solution
The design shifts the application of magnetic force to rotate the fan beyond the blade tips, utilizing a combination of permanent and electromagnets to reduce the torque required, integrates the motor rotor and fan as one assembly, and employs variable pitch blades to optimize airflow and pressure, while minimizing the size of magnetic components and manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If magnetic force is applied at the hub to rotate the fan blades, then the fan can be driven directly without transmission, but the torque required is high due to aerodynamic drag at blade tips
Solution Approach 1:
The patent applies magnetic force at the blade tips rather than at the hub, changing the spatial dimension of force application. This peripheral application point creates a longer moment arm, reducing the torque required to overcome aerodynamic drag while maintaining direct drive simplicity
2Manufacturing precision
If the spacing between rotor tips and duct wall is increased, then manufacturing tolerances are easier to achieve, but turbulence is generated at rotor tips reducing fan efficiency
Solution Approach 1:
The patent varies the spacing between rotor tips and duct wall across different operational parameters. The clearance is optimized for each operating condition, allowing larger clearances at low speeds and smaller clearances at high speeds, thus maintaining efficiency across the full operating range while accommodating manufacturing tolerances
3Power
If conventional electric motors are used to drive the fan, then high torque is produced for starting and acceleration, but power consumption is high during continuous operation
Solution Approach 1:
The patent employs variable pitch blades that dynamically adjust the angle of attack during operation. During startup, the blades are positioned at a low pitch angle requiring minimal torque. Once operational speed is reached, the pitch angle is increased to optimize airflow and reduce power consumption during continuous operation
4Loss of energy
If close tolerances are used for rotor tip clearance, then fan efficiency is maximized, but manufacturing cost increases due to highly precise machining requirements
Solution Approach 1:
The patent optimizes rotor tip clearance as a variable parameter rather than maintaining a fixed minimum clearance. By allowing larger clearances in certain operating conditions and configurations, the design reduces manufacturing complexity and cost while maintaining acceptable efficiency levels through compensating aerodynamic design features
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 approach reduces power consumption, increases efficiency, and allows for versatile operation across various pressures and flow rates, minimizing deformation and noise, thus enhancing the fan's performance and longevity while reducing manufacturing precision requirements.
Implementation Method 1
a motor that applies a magnetic force to rotate the fan
Implementation Method 2
The force resisting the fan's rotation during production of air flow is aerodynamic drag, including profile and induced drag
Data Source
AI summary
The ideal design for a fan with variable performance that can replace a family of current axial flow ducted, un-ducted, and centrifugal fan designs by meeting air flow and pressure requirements while drawing less electric current to rotate and thus produce the required flow not only would reduce cost of operation over the life of the fan but opens new possibilities for direct connection to solar collection systems by greatly extending the life of the battery charge employed by the designer of the collection system. In addition the entry of flying machines using pairs of lifting fans such as hover bikes and quadcopters, manned or unmanned is driving a need to re-examine the application of force applied to rotate these fans to achieve a reduction in aircraft weight and increase flying time for a given battery charge or load of fuel.