Valve Lifter Key Pin Contoured Surface Misalignment
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Solution Overview
Problem
Existing strategies for limiting rotational misalignment of valve lifters in internal combustion engines are either specific to certain engine designs or duty cycles, leading to issues like excessive wear and premature failure, and either severely restrict rotation or complicate the load paths and dynamics of the system.
Innovation Solution
A key pin with a contoured outer surface is used, which includes a plateau and descending slopes, positioned within a slot in the engine housing to contact the housing at different rotational orientations of the valve lifter, allowing for some rotation while preventing misalignment and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing anti-rotation devices are used to prevent valve lifter rotation, then misalignment is limited, but device complexity increases and system dynamics are complicated
Solution Approach 1:
The patent extracts the anti-rotation function from a complex dedicated device and integrates it into the existing key pin component. The key pin's contoured outer surface directly provides the anti-rotation mechanism by contacting the engine housing at specific orientations, eliminating the need for separate anti-rotation devices and reducing overall system complexity while maintaining misalignment prevention
Solution Approach 2:
The key pin is designed to perform multiple functions simultaneously: it provides positioning, allows for thermal expansion, and prevents rotation through its contoured outer surface. This multi-functional design eliminates the need for separate components for each function, reducing device complexity while maintaining reliability
2Reliability
If valve lifter rotation is severely restricted, then misalignment is prevented, but system dynamics and load paths are complicated
Solution Approach 1:
The patent implements a dynamic anti-rotation mechanism where the key pin can rotate slightly within acceptable limits before engaging the engine housing contours. This allows the system to adapt to thermal expansion and loading conditions while maintaining proper alignment, avoiding the complications of rigid restriction mechanisms and simplifying load paths
3Device complexity
If valve lifter rotation is permitted, then system dynamics are simplified, but misalignment and wear increase
Solution Approach 1:
The patent converts the potential harm of rotation into a beneficial feature by designing the contoured outer surface of the key pin to engage the engine housing at specific orientations. This controlled engagement prevents excessive rotation and misalignment while allowing sufficient movement to accommodate thermal expansion and simplify system dynamics, thereby reducing wear without over-constraining the system
Data Source
AI summary
An internal combustion engine includes a housing defining a lifter bore, and a slot in communication with the lifter bore. A valve lifter assembly is positioned within the lifter bore such that a key pin of the valve lifter assembly extends into the slot. The key pin has a contoured outer surface contacting the engine housing within the slot at a first and a second rotational orientation of the valve lifter, to limit misalignment thereof.