Stator Sleeve Cooling Layout With Oil-Water Leak Isolation
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Solution Overview
Problem
Existing electric traction machines face challenges in efficiently cooling the stator within constrained installation space and weight conditions, where traditional winding overhang cooling systems using external tubing or distribution rings are not feasible.
Innovation Solution
The electric traction machine incorporates a stator sleeve that surrounds the stator radially, allowing for efficient heat conduction. A pressurized oil cooling channel and a water cooling channel are integrated between the stator sleeve and the housing, with a compensating chamber preventing oil from contaminating the water cooling channel, thus enabling effective cooling while minimizing space and weight requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional winding overhang cooling systems with external tubing or distribution rings are used, then cooling effectiveness is improved, but installation space requirements increase and weight increases
Solution Approach 1:
The patent combines multiple cooling functions into a single integrated stator sleeve structure. The stator sleeve integrates the cooling liquid line (groove-shaped liquid channel), the pressurized oil cooling channel, and the water cooling channel into one component, eliminating the need for separate external tubing and distribution rings. This merging reduces installation space while maintaining comprehensive cooling coverage for the stator core and winding overhangs.
Solution Approach 2:
The stator sleeve serves multiple functions simultaneously: it provides structural support for the stator, acts as a cooling liquid reservoir, contains integrated cooling channels for both oil and water circulation, and provides cooling surfaces for both the stator core and winding overhangs. This multi-functionality eliminates the need for separate cooling components, reducing overall installation space and weight.
2Volume of moving object
If pressurized oil cooling channel is integrated close to water cooling channel to save space, then installation space is reduced, but risk of oil contamination to water cooling channel increases
Solution Approach 1:
The patent introduces a compensating chamber as an intermediary space between the pressurized oil cooling channel and the water cooling channel. This compensating chamber acts as a buffer zone that prevents direct contact between oil and water cooling systems. The sealing element is positioned to seal against the housing in this intermediary space, creating an effective barrier that prevents oil contamination while allowing the channels to be integrated closely for space efficiency.
Solution Approach 2:
The cooling system is segmented into distinct zones: the pressurized oil cooling channel zone, the compensating chamber zone with sealing elements, and the water cooling channel zone. This segmentation creates physical barriers and pressure zones that prevent oil from migrating into the water cooling channel, even when the channels are integrated in a space-constrained environment.
3Reliability
If double elastomer seal is used to prevent oil contamination, then sealing reliability is improved, but assembly difficulty increases due to high frictional forces
Solution Approach 1:
The patent extracts the sealing function from the stator sleeve assembly and relocates it to the housing. The sealing element is mounted in a sealing recess of the housing, where it seals against the housing bore rather than requiring dual seals on the stator sleeve. This extraction eliminates the need for double elastomer seals on the stator sleeve, reducing assembly friction while maintaining sealing reliability through the compensated pressure design.
4Temperature
If stator is pressed into stator sleeve for heat conduction, then heat conduction efficiency is improved, but assembly force requirements increase
Solution Approach 1:
The patent applies localized thermal contact enhancement at the interface between the stator outer surface and the stator sleeve inner surface. The stator sleeve is designed with a precisely fitted bore that creates optimal thermal contact at the critical heat transfer interface. This localized quality enhancement ensures efficient heat conduction from the stator to the cooling channels without requiring excessive assembly force, as the contact is concentrated at the most thermally critical areas.
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 allows for simple and efficient cooling of the stator, reducing the risk of overheating and maintaining power output, while also simplifying assembly and ensuring reliable sealing, thus optimizing installation space and weight usage.
Implementation Method 1
By virtue of the fact that the stator is pressed into the stator sleeve, the circumferential outer surface of the stator rests in surface contact against the internal inner surface of the stator sleeve. Particularly good heat conduction from the stator to the stator sleeve is thereby ensured.
Implementation Method 2
Jacket cooling of the stator sleeve takes place via the water cooling channel, with heat being absorbed by the stator sleeve by cooling water flowing in the water cooling channel.
Implementation Method 3
heat being absorbed by the stator sleeve by cooling water flowing in the water cooling channel
Implementation Method 4
A compensating chamber is kept free axially between the at least one pressurized oil cooling channel and the water cooling channel closest thereto, which compensating chamber is configured to collect oil that has emerged from the pressurized oil cooling channel. By virtue of the collection of the oil in the compensating chamber, the oil that has emerged from the pressurized oil cooling channel is at a lower pressure
Data Source
AI summary
An electric traction machine for a motor vehicle includes a rotor, a stator, a stator sleeve into which the stator is pressed, and a housing. The housing, together with which the stator sleeve, delimits at least one pressurized oil cooling channel and at least one water cooling channel, wherein an equalization chamber is kept free axially between the at least one pressurized oil cooling channel and the water cooling channel closest thereto, which equalization chamber is configured to collect oil that has leaked out of the pressurized oil cooling channel.