Outer-Rotor BLDC Motor Venting for Compact Self-Cooling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
There is a need for a compact outer-rotor brushless direct-current (BLDC) motor with high power density suitable for portable power tool applications, as existing solutions often require larger motor diameters to achieve sufficient cooling without additional fans.
Innovation Solution
The design incorporates a compact outer-rotor BLDC motor with a fan integrated into the rotor shaft, utilizing exhaust and intake openings for airflow to generate cooling airflow within the motor can, eliminating the need for additional cooling fans and maintaining a small motor diameter, with the fan diameter being smaller than or equal to the outer rotor diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the motor diameter is reduced to achieve a compact form factor, then the portability and size requirements are met, but the cooling capability deteriorates
Solution Approach 1:
The fan is integrated directly into the rotor shaft, merging the cooling function with the rotational component. This eliminates the need for separate cooling mechanisms and allows effective cooling within a compact motor diameter, as the fan rotates with the rotor to generate cooling airflow through the motor can.
Solution Approach 2:
The rotor shaft itself serves dual purposes: driving the motor and rotating the fan for cooling. The motor's operational rotation automatically drives the cooling fan, making the system self-cooling without requiring additional power or separate cooling components.
2Temperature
If additional cooling fans are added to improve cooling capability, then the temperature control improves, but the device complexity and size increase
Solution Approach 1:
The cooling fan is merged with the rotor shaft into a single integrated component. This eliminates the need for additional separate fans, reducing device complexity while maintaining effective cooling capability through the unified rotating structure.
3Temperature
If the fan diameter is increased to improve cooling airflow, then the cooling capability improves, but the motor diameter increases
Solution Approach 1:
The cooling airflow is optimized by utilizing the axial direction through the motor can rather than relying solely on radial fan diameter. The fan generates airflow along the axis of rotation, allowing effective cooling with a compact fan diameter that fits within the motor can.
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 configuration provides effective cooling for the motor and power tool components without additional fans, achieving high rotational speeds and maintaining a compact form factor, suitable for portable power tools.
Implementation Method 1
a fan mounted on the rotor shaft inside the motor can to generate an airflow through the motor can
Implementation Method 2
an outer rotor comprising a cylindrical rotor core supporting at least one permanent magnet around an outer surface of the stator core
Data Source
AI summary
An outer-rotor brushless direct-current motor is provided. The motor includes a motor can that supports the motor components and a fan mounted on a rotor shaft inside the motor can to generate an airflow through the motor can. The motor can includes exhaust openings formed around the fan to allow the airflow to be expelled radially away from the fan, and intake openings formed at a distance from the exhaust openings to allow an airstream to be received radially into the motor can.