Electric Machine Coil End Cooling via Gravity Distribution
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Solution Overview
Problem
Existing cooling structures for vehicle-mounted electric rotating machines suffer from non-uniform cooling due to coolant flow by gravity, leading to increased manufacturing costs and inefficiencies, particularly in designs requiring coolant supply pumps and complex coolant passages.
Innovation Solution
A coolant supply section that directs coolant to the upper peripheral surface of the coil ends, utilizing gravity to ensure even cooling across the cylindrical coil ends with flat axial surfaces and circular inner and outer surfaces, eliminating the need for pumps and complex passages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If coolant passage is designed as a closed space with oil chamber surrounding coil end, then cooling coverage is improved (entire surface becomes wet), but fluid resistance increases requiring coolant supply pump which increases manufacturing cost
Solution Approach 1:
The coolant supply system is segmented into multiple independent coolant supply openings distributed across the stator core end surface, rather than using a single centralized pump-driven system. This segmentation allows gravity to effectively distribute coolant to multiple locations simultaneously, reducing the need for complex pressurized delivery mechanisms.
Solution Approach 2:
Instead of using a pump to push coolant through closed passages against gravity, the invention inverts the approach by allowing coolant to flow naturally under gravity from upper to lower regions. The coolant supply openings are positioned to exploit gravitational flow, eliminating the need for active pumping while maintaining effective cooling coverage.
2Device complexity
If coolant flows down on coil end surface by gravity action, then cooling system simplicity is improved, but non-uniform cooling occurs as some parts of surface do not become wet
Solution Approach 1:
Different regions of the stator core end surface are provided with coolant supply openings at optimally positioned locations to ensure local coolant coverage. The openings are strategically placed considering the non-flat envelope surface geometry, ensuring that coolant supplied to each local region effectively wets the underlying coil end portions in that specific area.
Solution Approach 2:
The cooling system transitions from relying solely on vertical gravity-driven flow to a multi-dimensional distribution network. Coolant supply openings are arranged in specific patterns across the end surface, creating a two-dimensional coolant distribution map that ensures comprehensive coverage despite surface irregularities, rather than relying only on one-dimensional vertical flow.
3Reliability
If coolant supply pump is installed to overcome fluid resistance, then coolant flow reliability is improved, but manufacturing cost increases
Solution Approach 1:
The coolant supply system is designed to be self-service by utilizing the natural gravitational force and the pressure generated by the coolant pump (which circulates coolant through the system) to deliver coolant through the openings. No additional supply pump is needed beyond the circulation pump, as the system self-regulates coolant delivery to the end surface based on gravitational flow and system pressure.
Solution Approach 2:
The coolant supply pump component is extracted from the system by replacing it with a passive gravity-driven distribution mechanism. The invention removes the need for an active supply pump while maintaining reliable coolant flow through strategically positioned openings that leverage gravitational flow and system circulation pressure.
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 configuration significantly enhances cooling performance while reducing costs by leveraging gravity to ensure uniform coolant distribution over the entire coil end surface, improving thermal management without the need for pumps or complex coolant systems.
Implementation Method 1
A coolant supply section that directs coolant to the upper peripheral surface of the coil ends, utilizing gravity to ensure even cooling across the cylindrical coil ends
Data Source
AI summary
The electric rotating machine includes a rotor relatable around a rotating shaft disposed horizontally, a stator core formed with slots, and a stator coil constituted of in-slot portions each of which is accommodated in a corresponding one of the slots, and turn portions each of which connects corresponding adjacent two of the in-slot portions at a position outside the stator core. The turn portions form a coil end projecting axially outward from an end surface of the stator core at each of both axial end sides of the stator core. The coil end is formed in a cylindrical shape including an axial end surface of a flat shape, and inner and outer peripheral surfaces of a circular shape. The electric rotating machine further includes a coolant supply section to supply coolant to an upper part of the outer peripheral surface of the coil end.