Electric Machine Cooling via Segmented Airflow Paths
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Solution Overview
Problem
Electric machines, particularly internal stator machines, face efficiency reduction due to heat buildup in stator windings since they are not directly accessible to ambient surroundings, making effective heat removal challenging.
Innovation Solution
An electric machine design featuring a casing with air inlets and outlets, an outer rotor, a stator, a hub, and a fan to enhance airflow for cooling, along with fins on the hub and stator to facilitate heat dissipation, allowing air to flow through the machine and remove heat from the stator windings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the stator is positioned inside the rotor in an internal stator machine, then the machine structure is compact and space-efficient, but the stator windings are not directly accessible to ambient surroundings making heat removal difficult
Solution Approach 1:
The cooling system is segmented into multiple air flow paths: an outer cooling path around the rotor and an inner cooling path through the stator core. This segmentation allows heat removal from different locations simultaneously, addressing the heat removal difficulty while maintaining the compact internal stator configuration.
Solution Approach 2:
A cooling air flow acts as an intermediary medium between the stator windings (which cannot directly access ambient air) and the external environment. The cooling air absorbs heat from the stator windings through thermal convection and transports it to the air outlet, solving the heat removal problem for the enclosed stator.
2Temperature
If cooling air flow is increased to remove heat from stator windings, then heat removal efficiency improves, but the machine structure becomes more complex requiring additional cooling components
Solution Approach 1:
The rotor serves multiple functions: it acts as both the electromagnetic rotor and as a structural component that guides cooling air flow. The rotor includes air inlet openings and air outlet openings that are integral to its structure, allowing it to participate in both electromagnetic conversion and thermal management functions simultaneously.
Solution Approach 2:
The cooling air inlet and outlet passages are merged with the rotor structure itself rather than being separate components. The rotor end plates and rotor body incorporate the cooling passages, combining the cooling system with the electromagnetic structure to reduce 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
The enhanced airflow and fin structures effectively reduce heat in the stator windings, improving the efficiency and cooling of electric machines by directing air flow through multiple paths and using thermally conductive materials to enhance heat transfer.
Implementation Method 1
a fan positioned within the casing, the fan drawing air from the air inlet and exhausting air out the air outlet
Implementation Method 2
using thermally conductive materials to enhance heat transfer
Implementation Method 3
allowing air to flow through the machine and remove heat from the stator windings
Data Source
AI summary
An electric machine includes a casing have a first end plate and a second end plate, the first end plate having an air inlet and the second end plate having an air outlet; an outer rotor positioned inside the casing; a stator positioned inside the outer rotor; a hub positioned inside the stator; a fan positioned within the casing, the fan drawing air from the air inlet and exhausting air out the air outlet.