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Solution Overview
Problem
In refrigeration apparatus using carbon dioxide as a refrigerant, oil accumulation occurs at the connection portion between multi-hole flat pipes and cylindrical pipes, posing a significant issue.
Innovation Solution
A joint design that connects multi-hole flat pipes and cylindrical pipes, featuring a first connection portion, a body with increased inner dimensions in the vertical direction to prevent oil accumulation, and a reinforcement portion within the refrigerant flow passage to enhance strength and reduce expansion, allowing CO2 refrigerant passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a joint connects a multi-hole flat pipe and a cylindrical pipe with conventional design, then the connection is simple, but oil accumulates in the vicinity of the connection portion
Solution Approach 1:
The patent introduces a vertical dimension to the joint body, creating a stepped structure where the body's inside dimension in the vertical direction exceeds that of the first connection portion. This dimensional change creates a downward slope that prevents oil accumulation by directing oil toward the lower connection portion, resolving the oil accumulation issue while maintaining manufacturing simplicity
Solution Approach 2:
The joint employs an asymmetric design where the inside dimensions of the body differ between the vertical and horizontal directions, and between the two connection portions. Specifically, the body has a larger inside dimension vertically than the first connection portion, creating an asymmetric geometry that prevents oil pooling while maintaining ease of manufacture through conventional processing
2Ease of manufacture
If the joint body has uniform inside dimensions, then the manufacturing is simple, but oil accumulates and strength may be insufficient under high pressure
Solution Approach 1:
The patent applies dimensional change by making the body's inside dimension in the vertical direction larger than that of the connection portions, creating a stepped configuration. This resolves the contradiction by preventing oil accumulation through gravitational drainage while maintaining manufacturing simplicity through conventional forming processes
Solution Approach 2:
The patent changes the geometric parameters of the joint body, specifically creating a variation in inside dimensions along the vertical axis. The body has a larger inside dimension vertically compared to the connection portions, which prevents oil accumulation and enhances structural strength under high refrigerant pressure while remaining manufacturable
3Reliability
If the joint is designed to prevent oil accumulation, then reliability improves, but the structure becomes more complex
Solution Approach 1:
The patent resolves the contradiction by introducing a vertical dimension variation rather than adding complex components. The stepped structure with different inside dimensions in the vertical direction prevents oil accumulation through geometry alone, maintaining structural simplicity while improving reliability
Solution Approach 2:
The asymmetric design of the joint body, where the vertical inside dimension exceeds that of the connection portions, prevents oil accumulation without requiring additional components. This geometric asymmetry achieves reliable oil drainage while keeping the overall structure simple and manageable
Data Source
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AI summary
When a joint is used to connect a multi-hole flat pipe and a cylindrical pipe, a problem may occur in that oil accumulates in the vicinity of a connection portion. This problem may be significant in a refrigeration apparatus that uses a carbon dioxide refrigerant, for which oil has high importance. A joint (34) includes a first connection portion (301) that covers an outer side of an end portion of a multi-hole flat pipe (300), and a body (302) that is continuous from the first connection portion (301). An inside dimension (L302) of the body (302) in a vertical direction is larger than an inside dimension (L301) of the first connection portion (301) in the vertical direction. Here, the vertical direction is a thickness direction of the multi-hole flat pipe (300) (thickness T, width W, W > T).