Scroll Compressor Mechanism Using Mixed Cast Iron Materials
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Solution Overview
Problem
In scroll compressors, using the same material for both the fixed and movable scrolls leads to seizing issues when the scrolls are cast iron moldings and low strength/stiffness when they are grey iron castings, resulting in operational halts or deformation/rupture during downsizing attempts.
Innovation Solution
A compression mechanism where one scroll is a cast iron molding fabricated through semi-molten die casting and the other is a grey iron casting, with specific graphite area ratios and tensile strength ranges to prevent seizing and ensure sufficient strength and stiffness, allowing for downsizing while maintaining intake capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If both fixed scroll and movable scroll are made of cast iron molding fabricated through semi-molten die casting, then high strength and high stiffness are achieved, but seizing occurs between the scrolls causing operational halt
Solution Approach 1:
The patent applies different material compositions to different scrolls specifically at their contact surfaces. The movable scroll has a graphite area ratio of 3-8% while the fixed scroll has 7-13%, creating locally optimized surfaces that prevent seizing through controlled graphite distribution at the interface, while maintaining overall high strength through the semi-molten die casting process
Solution Approach 2:
The patent changes the graphite area ratio parameter between the two scrolls to prevent seizing. By setting specific graphite content ranges (movable: 3-8%, fixed: 7-13%) rather than using identical materials, the friction and seizing characteristics are improved while maintaining the high strength and stiffness benefits of semi-molten die casting
2Reliability
If both fixed scroll and movable scroll are made of grey iron casting, then seizing is reduced, but strength and stiffness become low causing deformation or rupture during operation
Solution Approach 1:
The patent uses composite material structure by combining grey iron base material with controlled graphite inclusions. The semi-molten die casting process creates a composite structure where graphite particles (3-13% area ratio) are distributed within the iron matrix, providing both seizure prevention through graphite lubrication and high strength through the composite structure
3Volume of moving object
If scroll portions are made thinner and longer to downsize the compression mechanism, then intake capacity is maintained, but deformation or rupture occurs due to low strength and stiffness
Solution Approach 1:
The patent changes the material parameters through semi-molten die casting to achieve higher strength and stiffness. This allows the scroll portions to be made thinner and longer for downsizing while the enhanced material properties (higher tensile strength and Young's modulus from semi-molten casting) prevent deformation or rupture under operating conditions
Data Source
AI summary
A compression mechanism is configured to be used in a scroll compressor. The compression mechanism includes a fixed scroll and a movable scroll. One of the fixed scroll and the movable scroll is a cast iron molding fabricated through semi-molten die casting, and the other of the fixed scroll and the movable scroll is a grey iron casting.