Encapsulated Electric Machine Cooling With Secondary Airflow
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Solution Overview
Problem
Existing encapsulated electrical machines face inefficiencies in cooling the rotor and stator, particularly in highly utilized systems where effective heat dissipation is required without direct external cooling, which can lead to overheating and reduced insulation effectiveness.
Innovation Solution
An encapsulated electrical machine with an internal air cooling system featuring at least two cooling channels and a fan for primary flow, along with a flow-generating element in the secondary volume to create turbulence, enhancing convective heat transfer and cooling efficacy without significantly impacting the primary flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If an internal cooling circuit with cooling channels is used in encapsulated electric machines, then heat dissipation from rotor and stator is improved, but cooling effectiveness is insufficient due to lack of turbulence and homogeneous heat distribution
Solution Approach 1:
The patent applies the principle of mechanical vibration by introducing a flow-generating element that creates turbulent flow in the cooling channels. This turbulence acts as a mechanical disturbance to the cooling air flow, enhancing heat transfer from the rotor and stator surfaces by preventing thermal boundary layer formation and promoting more uniform heat distribution throughout the cooling circuit.
2Strength
If encapsulation is used to protect the electric machine, then mechanical protection is improved, but heat dissipation to the environment is restricted
Solution Approach 1:
The patent introduces cooling air as an intermediary medium between the encapsulated active parts and the external environment. The cooling air circulates through internal cooling channels within the encapsulation, absorbing heat from the rotor and stator, and then exits through designated openings in the housing. This intermediary approach allows heat dissipation while maintaining the protective encapsulation.
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 solution provides effective and homogeneous cooling, reducing the risk of overheating and allowing for the use of cost-effective insulation even at high machine utilization, with improved temperature homogenization and reduced risk of hotspots in components like the stator winding.
Implementation Method 1
a fan for conveying cooling air in an encapsulated internal cooling circuit as primary flow through the at least two cooling channels
Implementation Method 2
a flow-generating element for generating a secondary flow is provided in the second volume
Implementation Method 3
enhancing convective heat transfer and cooling efficacy
Implementation Method 4
through which the heat generated in the rotor and, to some extent, also in the stator winding head is dissipated
Data Source
Figure 1
Figure 2
AI summary
The present invention relates to an electric machine (10) with an active arrangement (12) comprising a stator (14) and a rotor (18) rotatable about a rotor axis (16), wherein the active arrangement (12) is encapsulated by a housing (28) from the environment of the electric machine (10), wherein the active arrangement (12) has at least two cooling channels (30, 32) for guiding cooling air, which lead from a first volume (34) at a first axial end of the active arrangement (12) to a second volume (36) at a second axial end of the active arrangement (12), wherein a fan (38) is provided in the first volume (34) for conveying cooling air in a cooling circuit as primary flow through the at least two cooling channels (30, 32), wherein a flow-generating element (40) is provided in the second volume (36) for generating a secondary flow.