Dual-Fluid Stator Cooling for Winding Head Lubrication
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Solution Overview
Problem
Existing electric machines face challenges in simultaneously achieving high levels of cooling, lubrication, and oxidation protection, often requiring trade-offs that do not fully exploit the machine's potential.
Innovation Solution
The electric machine incorporates a dual cooling system, with a first cooling system using water-based fluid for efficient cooling in the stator stack section and a second cooling system using oil-based fluid with spray nozzles or bores directed at the stator winding heads for additional cooling and lubrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single cooling system is used for the electric machine, then the device complexity is reduced, but the cooling efficiency and lubrication performance deteriorate
Solution Approach 1:
The cooling system is divided into two separate systems: a first cooling system with a first cooling fluid for general cooling, and a second cooling system with a second cooling fluid for targeted cooling and lubrication of the stator winding heads. This segmentation allows each system to be optimized for its specific function, resolving the contradiction between simplicity and performance.
Solution Approach 2:
The second cooling fluid is directed specifically to the stator winding heads through spray nozzles or bores, providing localized cooling and lubrication where it is most needed. This local quality approach ensures high-performance cooling and lubrication at critical locations without requiring the entire system to be complex.
2Power
If water-based cooling fluid is used for high thermal capacity cooling, then cooling power is improved, but lubrication capability deteriorates
Solution Approach 1:
The cooling function and lubrication function are separated into two different fluids: the first cooling fluid (water-based) provides high cooling power, while the second cooling fluid (oil-based) provides lubrication. This segmentation resolves the contradiction between cooling power and lubrication capability.
Solution Approach 2:
The second cooling fluid acts as an intermediary that delivers both cooling and lubrication functions to the stator winding heads. By introducing this intermediate substance with dual properties, the system achieves both high cooling power and adequate lubrication without direct conflict between the two requirements.
3Object-generated harmful factors
If oil-based cooling fluid is used for lubrication, then lubrication performance is improved, but cooling efficiency deteriorates
Solution Approach 1:
The lubrication function is separated from the main cooling function, with the second cooling fluid (oil-based) dedicated to lubrication and the first cooling fluid (water-based) dedicated to high-efficiency cooling. This segmentation allows each fluid to excel at its primary function without compromise.
4Device complexity
If a single cooling fluid is used throughout the electric machine, then the device complexity is reduced, but oxidation protection capability deteriorates
Solution Approach 1:
The second cooling fluid is applied locally at the stator winding heads where oxidation risk is highest, providing targeted oxidation protection without requiring the entire cooling system to use oxidation-inhibiting fluids. This local quality approach maintains simplicity while achieving oxidation protection where needed.
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 dual cooling system enables effective cooling and lubrication of both the stator stack section and the stator winding heads, while preventing oxidation, thus maximizing the potential of the electric machine.
Implementation Method 1
a first cooling system based on a first cooling fluid around the stator lamination stack
Implementation Method 2
a first cooling channel of the first cooling system, wherein the first cooling channel is formed between the inner housing part and the outer housing part
Implementation Method 3
the separate second cooling system comprises spray nozzles or bores, which are directed towards at least one of the stator winding heads
Implementation Method 4
in addition the stator winding heads can be cooled and a lubricant can be brought into the interior of the electric machine
Implementation Method 5
By the proposed measures, also unwanted oxidation can be avoided in the interior of the electric machine
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
An electric machine (1, 1a..1c) is disclosed, which comprises a machine housing (2a..2c), a stator (3) and a rotor (5). Stator windings (7) comprise a stack section (B), in which they run within the stator lamination stack (6), and stator winding heads (C, C'), where they run out of the stack section (B). The machine housing (2a..2c) comprises a first cooling system (9) based on a first cooling fluid around the stator lamination stack (6) and a separate second cooling system (10, 10') based on a separate second cooling fluid. The separate second cooling system (10, 10') comprises spray nozzles or bores (11, 11'), which are directed towards at least one of the stator winding heads (C, C'). Furthermore, a vehicle (23) with such an electric machine (1, 1a.. 1c) is disclosed.