Piston Assembly Guide Rod with Expanding Tip
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Solution Overview
Problem
Existing piston assembly methods for engines with split connecting rods are complex and costly, requiring synchronization of movement mechanisms and are not suitable for connecting rods with bag-like holes, leading to potential damage during piston insertion.
Innovation Solution
A piston assembly method using a guide rod with a diameter-expanding tip end to engage with the connecting rod, allowing for simple and synchronized insertion of the piston into the cylinder bore without direct contact with fractured surfaces, and an apparatus that includes a guide rod drive portion, a guide rod engaging portion, and a connecting rod cap tightening portion to facilitate this process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If connecting rod guides are inserted into the cylinder bore before piston insertion to prevent contact with fractured surfaces, then the quality of connecting rod end surfaces is improved, but the device complexity and manufacturing cost increase due to synchronization requirements
Solution Approach 1:
A guide rod with a diameter-expandable tip end portion is introduced as an intermediary tool. The guide rod is inserted into the cylinder bore first, then its tip end portion is expanded to engage with the connecting rod's hole, serving as a mediator to guide the connecting rod and piston into the cylinder bore without direct contact between the fractured surface and guiding components.
Solution Approach 2:
The guide rod's tip end portion is designed to be dynamically changeable in diameter. It starts with a smaller diameter for easy insertion into the cylinder bore, then expands to a larger diameter to engage with the connecting rod's hole, providing adaptive functionality throughout the assembly process.
2Reliability
If connecting rod guides are used to restrict oscillation during piston insertion, then the reliability of the assembly process is improved, but the ease of manufacture deteriorates due to synchronization control requirements
Solution Approach 1:
The guide rod acts as a simple intermediary component that provides reliable guidance without requiring complex synchronization mechanisms. It is inserted into the cylinder bore, engages with the connecting rod, and naturally guides the assembly process without needing coordinated movement control.
Solution Approach 2:
The guide rod is designed as a simple, inexpensive tool that can be easily manufactured and discarded or reused. It serves its guiding function during the assembly process and can be removed afterward, eliminating the need for expensive, complex, and durable synchronized movement mechanisms.
3Ease of operation
If the guide rod tip end portion is expanded to engage with the connecting rod hole, then the ease of operation is improved, but the device complexity increases due to the expansion mechanism
Solution Approach 1:
The diameter of the guide rod's tip end portion is changed as a key parameter. It is inserted with a smaller diameter and then expanded to a larger diameter to engage with the connecting rod's hole, providing ease of operation through a simple parameter change rather than a complex structural mechanism.
Solution Approach 2:
Only the tip end portion of the guide rod is designed with diameter-expandable capability, while the rest of the guide rod maintains a simple cylindrical structure. This localized complexity minimizes overall device complexity while providing the necessary engagement functionality.
Data Source
AI summary
A guide rod, which has a diameter expandable tip end portion and restricts the oscillation of a connecting rod and a piston, is inserted into a cylinder bore via an opening adjacent to a crank chamber of the cylinder bore, and the piston is inserted into the cylinder bore via a cylinder head mounting side opening with the connecting rod positioned at a leading end. The diameter of the tip end portion of the guide rod is increased in a hole of a semi-circular arc-shaped end portion positioned at tip end of the connecting rod in the insertion direction, and thus the connecting rod is engaged with the guide rod. The guide rod moves and the connecting rod is pulled into the cylinder bore until the semi-circular arc-shaped end portion of the connecting rod sits on a crankpin of a crankshaft.