Electric Compressor Rotor Cooling for Permanent Magnet Protection
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Solution Overview
Problem
Conventional electric compressors for vehicles suffer from inadequate cooling of the rotor, particularly the permanent magnet, leading to demagnetization at high temperatures, which deteriorates motor performance.
Innovation Solution
The electric compressor design includes a rotor with slots for permanent magnets, separated cooling holes, and refrigerant through-holes in the cover, allowing refrigerant to flow through these holes to cool the magnets effectively, with balance weights to prevent vibration and interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If refrigerant passes only through the outside of the rotor, then the structure is simple, but the cooling effect of the permanent magnet is insufficient
Solution Approach 1:
The cooling structure is segmented into multiple cooling holes distributed around the rotor circumference, with each cooling hole independently cooling specific permanent magnets in corresponding slots. This segmentation allows targeted cooling of heat-prone areas without requiring a complete structural overhaul.
Solution Approach 2:
Cooling holes are strategically positioned to provide localized cooling to permanent magnets that generate the most heat during operation. The cooling refrigerant is directed specifically to these critical areas rather than uniformly cooling the entire rotor, optimizing cooling efficiency where it is most needed.
2Temperature
If cooling holes are formed in the rotor, then the permanent magnet cooling is improved, but the rotor structure becomes more complex
Solution Approach 1:
The rotor structure is designed to serve multiple functions: the cooling holes not only cool the permanent magnets but also serve as structural elements within the rotor assembly. The same rotor body that holds the permanent magnets in slots also incorporates the cooling holes, eliminating the need for separate cooling components.
Solution Approach 2:
The cooling function is merged with the rotor structure itself. The cooling holes are formed directly in the rotor body, combining the rotor's mechanical function with its thermal management function into a single integrated component rather than adding separate cooling apparatus.
3Temperature
If refrigerant flow path is extended through the rotor, then cooling performance is improved, but the refrigerant flow resistance increases
Solution Approach 1:
The refrigerant flow path is designed to be dynamic and adaptive, with multiple cooling holes allowing the refrigerant to take optimal paths through the rotor. The refrigerant can flow through different combinations of cooling holes depending on operating conditions, maintaining efficient flow while providing comprehensive cooling.
Solution Approach 2:
The cooling approach transitions from external-only cooling to internal cooling by introducing cooling holes within the rotor body. This dimensional change allows the refrigerant to access and cool the permanent magnets from the inside, dramatically improving cooling effectiveness without significantly increasing flow path length or resistance.
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
Enhances cooling performance of the permanent magnet, preventing demagnetization and maintaining motor stability, thereby improving the overall reliability and performance of the electric compressor.
Implementation Method 1
Refrigerant flows into the cooling hole... the refrigerant flowing through the cooling hole cools the permanent magnets located on both sides of the cooling hole
Data Source
AI summary
An electric compressor including: a rotating shaft configured to drive a compression mechanism; a rotor configured to have a rotating shaft through-hole into which the rotating shaft is inserted; a cover configured to cover a longitudinal end of the rotor; and a stator configured to be installed on a radially outer side of the rotor. A plurality of slots into which a permanent magnet is inserted is formed to be spaced apart from each other in the rotor in a circumferential direction of the rotor. A cooling hole is formed in both ends of the slot, and the slot and the cooling hole are spatially separated. Refrigerant flows into the cooling hole and cools the permanent magnet. Accordingly, it is possible to improve the cooling performance of the permanent magnet.