Eccentric Rod Piston Assembly via Injection-Molded Retaining Ring
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Solution Overview
Problem
Existing methods face challenges in simply and reliably producing a unit of eccentric rod and piston with the eccentric rod secured in the piston via a closed retaining ring, requiring complex component attachment and manufacturing processes.
Innovation Solution
A method involving an injection-molding tool is used to form a circumferentially closed retaining ring between the piston, the second end of the eccentric rod, and the injection-molding tool, ensuring a secure and reliable attachment of the eccentric rod to the piston using a ball head design and thermoplastic injection-molding material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional methods are used to attach the eccentric rod to the piston with a closed retaining ring, then the attachment is secure, but the manufacturing process becomes complex
Solution Approach 1:
The patent combines the retaining ring formation process with the piston manufacturing process by using injection molding to create the retaining ring as an integrated part of the piston structure. This merging of operations eliminates separate assembly steps and reduces manufacturing complexity while maintaining secure attachment of the eccentric rod to the piston
2Reliability
If a closed retaining ring is used to secure the eccentric rod in the piston, then the attachment is reliable, but the manufacturing process requires multiple components and steps
Solution Approach 1:
The retaining ring is merged with the piston structure through injection molding, transforming what would be a separate component requiring assembly into an integrated feature of the piston itself. This single-step formation process improves ease of manufacture while ensuring reliable attachment through the molded connection
3Reliability
If multiple components are used for attaching the eccentric rod to the piston, then the attachment can be secure, but the number of manufacturing steps increases
Solution Approach 1:
The injection molding process merges the creation of the retaining ring with the piston manufacturing operation, eliminating the need for separate component fabrication and assembly steps. This integration increases manufacturing efficiency by reducing the total number of operations required to achieve secure attachment
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 method simplifies and reliably secures the eccentric rod in the piston, providing a robust and efficient assembly with a good articulated attachment, reducing manufacturing complexity and ensuring reliable operation.
Implementation Method 1
introducing an injection-molding tool into the piston; injection-molding a circumferentially closed retaining ring between the piston, the second end of the eccentric rod and the injection-molding tool
Data Source
AI summary
A method is provided for producing an assembly of an eccentric rod (15, 16) and a piston (20, 21) of a connecting rod of an internal combustion engine having an adjustable compression ratio. The method includes providing an eccentric rod (15, 16) having a first end (36, 37) for attachment to an eccentric lever of an eccentric adjusting device of the connecting rod and a second end (38, 39) for attachment to a piston (20, 21) that can be guided in a hydraulic chamber of the connecting rod. The method then includes arranging the second end (38, 39) of the eccentric rod (15, 16) in the piston (20, 21); introducing an injection-molding tool (47) into the piston (20, 21); and injection-molding a circumferentially closed retaining ring (43) between the piston (20, 21), the second end (38, 39) of the eccentric rod (15, 16) and the injection-molding tool (47).