Dual Impeller Cooling for Internal Rotor Motor Temperature Control
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Solution Overview
Problem
Internal rotor motors used in fans face challenges in maintaining performance and service life due to high winding temperatures, limiting maximum power output at constant speed.
Innovation Solution
The implementation of two axially opposite cooling impellers, one associated with motor electronics and the other adjacent to the stator, generates dual cooling air flows to actively cool both motor electronics and stator windings, reducing temperature and increasing power output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the motor is designed with compact dimensions, then the motor size is reduced, but the cooling performance deteriorates leading to high winding temperatures
Solution Approach 1:
The cooling system is segmented into two separate cooling impellers: a first cooling impeller for cooling the motor electronics on the drive shaft side, and a second cooling impeller for cooling the stator windings. This segmentation allows each impeller to be optimized for its specific cooling target, achieving effective cooling in a compact motor design without the temperature penalties that would result from a single, potentially larger cooling system.
2Power
If cooling systems are added to reduce winding temperature, then the maximum power output can be increased, but the device complexity increases
Solution Approach 1:
The cooling impellers are integrated with the rotor structure, merging the cooling function into the existing rotating components. The first cooling impeller is connected to the drive shaft, and the second cooling impeller is connected to the rotor, allowing both cooling functions to be achieved through the rotor's rotation without adding separate driving mechanisms or control systems.
Solution Approach 2:
The rotor serves multiple functions: it generates the magnetic field for motor operation and simultaneously drives both cooling impellers to provide cooling. This multi-functionality reduces the need for additional dedicated cooling components and control systems, thereby limiting the increase in device complexity while still achieving the power increase enabled by better cooling.
3Temperature
If cooling air flows are directed along the stator windings, then the winding temperature is reduced, but the motor dimensions may need to increase to accommodate the cooling channels
Solution Approach 1:
The cooling approach transitions from radial cooling channels (which would consume axial space) to axial cooling air flows that move parallel to the stator winding surface. The second cooling impeller generates an axial cooling air flow that travels along the inner circumferential surface of the stator and is blown off radially on the outside of the stator windings, effectively cooling the windings without requiring additional radial or axial space for cooling channels.
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 achieves a significant reduction in winding temperature, allowing for higher maximum power output while maintaining speed, and extends the service life of the motor, with a compact design that can replace larger motors.
Implementation Method 1
The first cooling impeller is associated with the drive shaft and disposed on the first axial side of the stator and generates a first cooling air flow at least to the motor electronics during operation of the electric motor
Implementation Method 2
The second cooling impeller has impeller blades generating a second cooling air flow at least in the axial direction along the stator during operation of the electric motor
Implementation Method 3
The second cooling impeller is configured as a radial impeller. Thus, the cooling air flow can have a double cooling effect on components of the stator
Data Source
AI summary
The disclosure relates to an electric motor, in particular configured as an internal rotor motor, for driving a fan having a stator, a rotor, a drive shaft, motor electronics disposed on a first axial side of the stator, a first cooling impeller which is associated with the motor electronics and disposed on the first axial side of the stator on the drive shaft and generates a first cooling air flow at least to the motor electronics during operation of the electric motor, and a second cooling impeller which is disposed immediately adjacent the stator on a second axial side of the stator opposite the first axial side and has impeller blades that generate a second cooling air flow at least in the axial direction along the stator during operation of the electric motor.