Power Tool Fan Wheel Magnetic Coupling for Reduced Fan Losses
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Solution Overview
Problem
Conventional power tools with rigid mechanical connections between fan wheels and motor shafts suffer from cooling performance that increases with rotational speed, leading to high fan losses, especially in brushless motors with varying speed ranges, resulting in inefficient cooling and bulky tools.
Innovation Solution
A magnetic coupling is introduced between the fan wheel and motor shaft, allowing for decoupling of their rotational speeds, enabling independent control of cooling performance and reducing fan losses by preventing the fan wheel from rotating at the same speed as the motor shaft, especially at high rotational speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a rigid mechanical connection is used between the fan wheel and motor shaft, then the fan wheel rotates at the same speed as the motor shaft, but the cooling air flow cannot be set independently and fan losses increase by the power of three with rotational speed
Solution Approach 1:
The patent replaces the rigid mechanical connection between the motor shaft and fan wheel with a magnetic coupling system. This substitution allows the fan wheel to be driven magnetically rather than mechanically, enabling independent control of fan speed from motor speed and significantly reducing fan losses at high rotational speeds.
Solution Approach 2:
The magnetic coupling system allows dynamic adjustment of the fan wheel's rotational speed relative to the motor shaft speed. The fan can operate at optimized speeds for cooling efficiency while the motor operates at high speeds for power delivery, resolving the contradiction between speed and energy loss.
2Adaptability or versatility
If the fan wheel is rigidly mounted on the motor shaft, then the structure is simple, but the cooling performance cannot be independently controlled from motor rotational speed
Solution Approach 1:
By replacing the simple rigid mechanical mounting with a magnetic coupling system, the patent gains independent control capability for cooling performance. The magnetic coupling allows the fan to be driven without direct mechanical connection, enabling separate speed control while adding only moderate structural complexity.
3Adaptability or versatility
If separate motors are used for ventilation units to independently control cooling performance, then cooling can be set independently of motor speed, but the power tools become bulky and unwieldy
Solution Approach 1:
The patent merges the fan wheel drive function with the motor's magnetic field system. Instead of adding a separate ventilation motor, the existing motor's magnetic field is used to couple and drive the fan wheel, achieving independent cooling control while maintaining a compact tool design.
Solution Approach 2:
The motor system serves dual functions: directly driving the tool mechanism and magnetically coupling to drive the fan wheel for cooling. This multi-functionality eliminates the need for separate ventilation motors, keeping the tool compact while providing independent cooling control.
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 solution allows for improved cooling efficiency, reduced fan losses, and a more compact power tool design by decoupling the rotational speeds of the fan wheel and motor shaft, providing better adapted cooling airflow and reducing the need for separate ventilation units.
Implementation Method 1
a coupling is formed magnetically between the fan wheel and the motor shaft such that the motor shaft drives the fan wheel in a rotary movement with a speed that is less than a speed of the motor shaft
Data Source
AI summary
A power tool is provided having a motor and a motor shaft, wherein a fan wheel in the power tool is designed to generate an air flow for cooling the motor. The power tool provides a coupling formed magnetically between the fan wheel and the motor shaft such that the motor shaft drives the fan wheel in a rotary movement with a speed that is less than a speed of the motor shaft. As a result of the magnetic coupling of the fan wheel and motor shaft, the movements of the two components can be decoupled from one another such that an increase in the rotational speed of the motor shaft does not also result in an increased speed at the fan wheel. As a result, fan losses can be considerably reduced and the efficiency of the motor of the power tool can be significantly improved. A method is also provided for cooling a motor of a power tool, wherein there is a magnetic coupling between a fan wheel and a motor shaft of the power tool.