Reverse Flow Cooling for Fan Motor Thermal Management
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Air movers, particularly axial fans, face challenges in cooling motors due to thermal resistance and space constraints, limiting the ability to dissipate heat effectively, especially in low to medium power applications where external blowers are impractical and internal fans are inefficient.
Innovation Solution
The air mover utilizes a pressure difference between the upstream and downstream ends of the flow path to induce a reverse air flow through the motor, using inlet and outlet openings to facilitate forced convection cooling, allowing for a smaller motor size to fit within a compact flow path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the motor size is increased to provide sufficient shaft power, then the power output is improved, but the motor cannot fit inside the optimal flow path due to space constraints
Solution Approach 1:
The patent inverts the conventional cooling approach by using reverse flow cooling where air flows through the motor in the opposite direction of the main airflow. This allows the motor to be positioned optimally in the flow path while still achieving effective cooling, thus enabling a smaller motor size to provide the required shaft power without exceeding space constraints.
2Temperature
If conventional cooling methods are used, then the motor can be cooled, but the thermal resistance is very large preventing effective heat dissipation from internal components
Solution Approach 1:
The patent applies reverse flow cooling where air is directed to flow through the motor in the opposite direction of the main airflow. This inverted cooling approach creates direct contact between the cooling air and internal heat-generating components such as coils, bearings, power electronics and rotor conductors, significantly reducing thermal resistance and improving heat dissipation effectiveness.
Solution Approach 2:
The patent extracts a portion of the main airflow to create a dedicated cooling flow path that passes through the motor. By separating this cooling flow from the main airflow path, the system can provide targeted cooling to the motor components without interfering with the primary air moving function, thus reducing thermal resistance effectively.
3Temperature
If internal fans are used to cool the motor, then cooling effectiveness is improved, but the device complexity and space requirements increase
Solution Approach 1:
The patent implements self-service cooling where the motor's own operation creates the pressure differential needed for cooling. The motor housing includes inlet and outlet openings that utilize the pressure difference between upstream and downstream ends of the flow path to naturally drive cooling air through the motor, eliminating the need for separate internal fans or external blowers.
Solution Approach 2:
The patent makes the main airflow serve dual functions: moving air through the system and cooling the motor simultaneously. By configuring inlet and outlet openings in the motor housing, the same airflow that performs the primary air moving function also provides cooling, eliminating the need for dedicated cooling devices and reducing overall system complexity.
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 reverse flow cooling technique effectively reduces thermal resistance and minimizes motor size, enabling efficient heat dissipation and improved thermal management within the motor housing, even in constrained spaces.
Implementation Method 1
a pressure difference between the upstream and downstream ends of the flow path to cause a portion of the air to flow back through the motor in order to cool the motor
Implementation Method 2
a pressure difference between the upstream and downstream ends of the flow path causes a portion of the air to flow into the inlet opening, through the motor and out the outlet opening
Data Source
AI summary
An air mover, such as a cooling fan, comprises a motor and an impeller which is driven by the motor to generate a flow of air through a flowpath. The motor comprises at least one inlet opening and at least one outlet opening, each of which is in fluid communication with the flowpath. In operation of the air mover, a pressure difference between the inlet and outlet openings causes a portion of the flow of air to flow into the inlet opening, through the motor and out the outlet opening to thereby cool the motor.