Brushless Cooling Fan with External Rotor and Controller Heat Sink
Solution Overview
Problem
Brushless DC motors in automotive cooling systems face reliability and efficiency issues due to high temperatures under the hood, where conventional cooling methods are insufficient, and existing solutions either complicate or fail to adequately address the thermal management needs of both the motor and electronic control systems.
Innovation Solution
A brushless motor cooling fan design featuring a high-efficiency external rotor BLDC motor with a rugged electronic controller positioned away from the motor, utilizing a heat sink and air ducts for cooling airflow, along with a centrifugal fan and skewed magnets to dissipate heat effectively, allowing the rotor and stator to directly dissipate heat to the surroundings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If BLDC motors are used in automotive cooling systems, then efficiency and reliability are improved, but the electronic controller is exposed to high temperatures that reduce its operating life
Solution Approach 1:
The electronic controller is extracted from the motor housing and positioned in a separate location on the fan assembly, away from the high-temperature motor environment. This physical separation allows the controller to operate in a cooler environment while the motor continues to function in the high-temperature under-hood conditions.
Solution Approach 2:
A heat sink is introduced as an intermediary component between the motor and the electronic controller. The heat sink absorbs and dissipates heat away from the controller, creating a thermal barrier that protects the temperature-sensitive electronics while allowing the motor to operate in the high-temperature environment.
2Device complexity
If the electronic controller is positioned close to the motor for compact design, then device complexity is reduced, but temperature increases reducing reliability
Solution Approach 1:
The fan assembly serves multiple functions: it provides the structural platform for mounting the controller away from the motor, acts as a heat dissipation pathway, and maintains compact overall dimensions. This multi-functional design achieves controller protection without significantly increasing assembly complexity.
3Reliability
If cooling mechanisms are added to protect the controller, then controller reliability is improved, but device complexity increases
Solution Approach 1:
The fan assembly's rotation and airflow generation serve a dual purpose: cooling the engine and simultaneously cooling the electronic controller. The same airflow that cools the motor also passes over the controller and heat sink, providing passive cooling without requiring additional active cooling components.
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 enhances the reliability and efficiency of the cooling fan by maintaining low electrical resistance, reducing operating temperatures, and extending the lifespan of the electronic controller and motor components in high-temperature environments.
Implementation Method 1
a heat sink that transfers heat away from the electronic controller
Implementation Method 2
a heat sink that transfers heat away from the electronic controller
Implementation Method 3
a plurality of air ducts through an electronic controller module, the air ducts drawing a cooling airflow from a static lower pressure of a rotating impeller
Implementation Method 4
a centrifugal fan and a plurality of skewed magnets inside the motor through a plurality of ducts in a shroud hub
Implementation Method 5
drawing a cooling airflow from a static lower pressure of a rotating impeller
Data Source
AI summary
A fan assembly with an impeller and shroud for application in a vehicle cooling system. The fan is powered by an external rotor brushless direct current (BLDC) motor having an electronic controller positioned away from the BLDC on an outer shroud wall with a plurality of ducts drawing an airflow from a static lower pressure created by the impeller, the airflow streaming over a heat sink disposed on the controller, exiting through a shroud. The static lower pressure air is pulled by a centrifugal fan and skewed magnets inside the motor through a plurality of ducts in a shroud hub, cooling the BLDC, maintaining low resistance for high efficiency. The BLDC is integrated into the assembly, having a stator fixed in the shroud hub and a rotor directly fused to the impeller, the shroud and impeller forming the BLDC motor without a housing, allowing the motor to easily dissipate heat.