Directly Cooled Windings With Turbulent Gap Flow
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Solution Overview
Problem
Existing electric machines face inefficiencies in heat dissipation due to laminar coolant flow in small diameter wire channels, leading to increased electric losses and limited current density.
Innovation Solution
An electric machine design with fluid-tight internal housings for windings, featuring coolant inlets and outlets, and gaps between neighboring windings for turbulent coolant flow, enhancing convective heat transfer and allowing independent design of wire diameter and coolant supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If small diameter wire channels are used for coolant flow, then the cooling system can be integrated within the winding structure, but the flow becomes mainly laminar leading to low heat transfer coefficients
Solution Approach 1:
The patent changes the flow regime parameter from laminar to turbulent by increasing mass flow rate, which transforms the heat transfer characteristics and significantly improves the heat transfer coefficient despite the small channel diameter
Solution Approach 2:
The patent applies hydraulic principles by using a pumped coolant circulation system with controlled mass flow rate to induce turbulent flow in the small diameter channels, leveraging fluid dynamics to overcome the natural tendency toward laminar flow in small passages
2Temperature
If high mass flow rate is used to achieve turbulent flow, then heat transfer coefficient improves, but the system requires extremely high flow rates to maintain turbulent flow in small diameters
Solution Approach 1:
The patent accepts the requirement for high mass flow rate as a necessary parameter change to achieve turbulent flow, and designs the cooling system to accommodate this requirement through appropriate pump selection and coolant circulation architecture
3Area of stationary object
If hollow wire design is used for direct cooling, then coolant contact area increases, but the material thickness of wires is limited leading to increased electric losses
Solution Approach 1:
The patent segments the cooling function from the electrical conductor function by using separate cooling channels in the stator structure, allowing the windings to be solid conductors optimized for electrical performance while the stator structure provides the cooling surface area
4Temperature
If cooling channels are integrated into the stator structure, then direct cooling of windings is achieved, but the structural design becomes more complex
Solution Approach 1:
The patent makes the stator structure multi-functional by integrating it with the cooling system, where the stator serves both as the mechanical support structure and as the coolant distribution manifold, eliminating the need for separate 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
Improves heat dissipation and current density by increasing convective heat transfer coefficients, reducing power losses, and enabling compact, efficient electric machines.
Implementation Method 1
the gaps are in fluid communication with the respective coolant inlet and the coolant outlet to be flown through by a coolant
Implementation Method 2
the at least one internal housing comprises a coolant inlet and a coolant outlet... a flow of coolant from the coolant inlet to the coolant outlet through the internal housing occurs
Implementation Method 3
In order to reach a turbulent flow for improved heat transfer, the mass flow rate needs to be extremely high
Implementation Method 4
the coolant remains inside the interior space or exits the interior space through the coolant outlet... a continuous flow of coolant from the coolant inlet to the coolant outlet through the internal housing occurs
Data Source
AI summary
An electric machine includes windings for creating electromagnetic fields and at least one fluid-tight internal housing. The group of windings is in an interior space of one of the at least one internal housing. Each of the at least one group of the windings includes at least two electric connecting sections for connecting the respective group of the windings to an external electrical circuit, wherein the at least two electric connecting sections reach from the interior space through a wall of the respective internal housing to outside the respective internal housing, wherein the at least one internal housing includes a coolant inlet and a coolant outlet, and wherein neighboring windings of the at least one group of the windings enclose gaps between each other, the gaps being in fluid communication with the respective coolant inlet and the coolant outlet to be flown through by a coolant.