Valvetrain Link Arm with Tapered Small End
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Solution Overview
Problem
Conventional valvetrain mechanisms experience oscillating arm leaning due to input loads from the link arm and link rod, which affects the mechanism's compactness and stability.
Innovation Solution
A valvetrain mechanism design where the link arm has a thinner small end compared to the large end, reducing the distance between loads and minimizing the moment that causes the oscillating arm to lean, with a drive shaft inserted through the large end and an oscillating arm connected via a first rotation support point, and a link rod connected via a second rotation support point on the same side as the valve lift control shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the link arm has a uniform thickness from large end to small end, then the structural strength is sufficient, but the distance between loads on the oscillating arm increases causing it to lean
Solution Approach 1:
The link arm is designed with non-uniform thickness: the large end has greater thickness to maintain structural strength and load-bearing capacity, while the small end has reduced thickness to minimize the distance between loads on the oscillating arm. This local differentiation resolves the contradiction by optimizing each section's thickness according to its specific functional requirements.
Solution Approach 2:
The solution addresses the leaning problem by modifying the thickness dimension of the link arm. By reducing the thickness at the small end, the moment arm distance between loads is shortened, thereby reducing the leaning moment on the oscillating arm while maintaining overall structural integrity through the thicker large end.
2Stability of the object's composition
If the distance between loads on the oscillating arm is reduced, then the oscillating arm leaning is minimized, but the link arm thickness must be reduced which may compromise strength
Solution Approach 1:
The link arm employs local quality differentiation with the large end having greater thickness for strength and the small end having reduced thickness for minimizing load distance. This resolves the contradiction by concentrating the thickness reduction only where it serves the stability function, while the large end maintains sufficient thickness for structural strength.
Data Source
AI summary
A valvetrain mechanism of an engine, including a drive shaft configured to rotate in synchronization with the engine, a link arm having a large end and a small end, the drive shaft being inserted into and passed through the large end, a valve lift control shaft disposed parallel to the drive shaft and having an eccentric portion, an oscillating arm disposed rotatably at the eccentric portion of the valve lift control shaft and interconnected with the small end of the link arm via a first rotation support point, a link rod interconnected with the oscillating arm via a second rotation support point positioned at a same side as the first rotation support point with respect to the valve lift control shaft, and an oscillating cam interconnected with the link rod via a third rotation support point and operated correspondingly with an operation of the drive shaft to thereby open a valve. A thickness of the small end of the link arm in a direction of the drive shaft is thinner than a thickness of the large end of the link arm in the direction of the drive shaft.