Liquid Cooled Electrical Machine With Tapered Chamber Flow Control
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Solution Overview
Problem
The increasing demand for compact and high-power electrical machines, such as Integrated Starter Generators (ISGs), poses a challenge in efficiently cooling the high heat generated by integrated electrical and electronic components, which is not adequately addressed by existing cooling systems.
Innovation Solution
The implementation of a flow control apparatus with a tapered chamber and guide member that varies the velocity of the coolant, combined with a housing design that includes axial and circumferential passages, and a mating member for sealing and vibration reduction, to achieve uniform thermal energy transfer and efficient cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the electrical machine housing is made more compact to reduce space in the vehicle's engine bay, then the volume occupied by the alternator is reduced, but the heat generated by the stator/rotor windings increases relative to the available cooling volume
Solution Approach 1:
The cooling system is segmented into multiple independent coolant passages: axial passages for cooling the stator, circumferential passages for cooling the rotor, and radial passages for cooling the bearing. This segmentation allows each component to be cooled independently and efficiently within the compact housing volume.
Solution Approach 2:
The cooling passages extend in multiple dimensions (axial, circumferential, and radial directions) throughout the housing, maximizing the cooling surface area and heat transfer efficiency within the limited volume available in the compact alternator design.
2Volume of moving object
If high-power components are integrated into the housing in the smallest possible volume to achieve compactness, then the volume of the ISG is reduced, but the heat generation significantly increases
Solution Approach 1:
Different regions of the housing are provided with different cooling characteristics: axial passages with specific cross-sectional areas for stator cooling, circumferential passages for rotor cooling, and radial passages for bearing cooling. Each passage is designed with local quality tailored to the specific thermal requirements of the component it serves.
Solution Approach 2:
A liquid coolant circulation system is implemented with inlet and outlet ports connected to the housing, allowing continuous flow of coolant through the internal passages to efficiently remove heat from all high-power components integrated within the compact ISG housing.
3Temperature
If coolant passages are added to cool multiple components, then the cooling capability is improved, but the device complexity increases
Solution Approach 1:
Multiple cooling functions (stator cooling, rotor cooling, bearing cooling) are merged into a single integrated housing structure with interconnected coolant passages. The coolant flows continuously through all passages in sequence, providing comprehensive cooling through one unified system rather than separate independent cooling systems.
Solution Approach 2:
The housing serves multiple functions simultaneously: it provides structural support, contains the electrical components, and acts as a heat exchanger through the integrated coolant passages. The same housing structure that contains the high-power components also provides the cooling pathways, eliminating the need for separate cooling housings or attachments.
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 ensures uniform cooling of electrical and electronic components, reduces the risk of temperature gradients, and maintains the components at optimal operating temperatures, thereby enhancing the performance and longevity of the ISG while minimizing fuel consumption.
Implementation Method 1
the velocity of a liquid in the first chamber is varied as the liquid is conveyed between the entrance aperture and the exit aperture, such that a transfer of thermal energy from a heat source to the liquid via the first wall is substantially uniform
Implementation Method 2
a transfer of thermal energy from a heat source to the liquid via the first wall is substantially uniform between the entrance aperture and the exit aperture
Data Source
AI summary
Flow control apparatus for an electrical machine and comprising an arrangement of shaped chambers and passages for conveying a liquid coolant. The rate of heat transfer from certain portions of the machine to the coolant is determined by the varying velocity of the liquid through the chambers, resulting in a generally uniform cooling of those portions of the machine.