Engine Valve Actuation Lash Prevention via Auxiliary Motion
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Solution Overview
Problem
Internal combustion engine systems with separate main and auxiliary valve actuation motion sources and components like lost motion components or automatic lash adjusters can over-extend, leading to poor performance and emissions due to lash creation, which complicates design and increases costs.
Innovation Solution
A system with a main and auxiliary valve actuation motion source, where the auxiliary motion source includes a lash-prevention valve actuation motion that matches the main valve actuation motions, preventing lash creation by ensuring the auxiliary motion load path remains in contact with the bridge pin, thus eliminating the need for complex configurations and lash adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate main and auxiliary valve actuation motion sources are used with lost motion components or automatic lash adjusters, then auxiliary valve actuation motions can be provided, but the components can over-extend creating lash between valve actuation components, leading to poor performance and emissions
Solution Approach 1:
The auxiliary cam is designed with a lash-prevention lobe that applies a preliminary counteracting force to prevent the loss motion component from over-extending. This preliminary anti-action occurs during the main valve actuation motion, where the auxiliary cam's lash-prevention lobe maintains contact with the auxiliary bridge pin, preventing the component from extending beyond its intended range and creating lash.
Solution Approach 2:
The auxiliary cam acts as an intermediary mechanism between the main valve actuation system and the lost motion component. By introducing this intermediate element with a specifically designed lash-prevention lobe, the system can provide auxiliary valve actuation motions while simultaneously preventing the harmful over-extension of the lost motion component.
2Adaptability or versatility
If lost motion components or automatic lash adjusters are used to accommodate auxiliary valve actuation, then auxiliary motions can be implemented, but design complexity and cost increase
Solution Approach 1:
The invention merges the auxiliary valve actuation function with the main valve actuation system by using the existing auxiliary cam and bridge pin infrastructure. The lash-prevention lobe is integrated into the auxiliary cam design, combining multiple functions (auxiliary actuation and lash prevention) into a single integrated component rather than adding separate complex mechanisms.
Solution Approach 2:
The auxiliary cam is designed to serve multiple functions: providing auxiliary valve actuation motions through its primary lobes and simultaneously preventing lash in the lost motion component through its lash-prevention lobe. This multi-functionality eliminates the need for separate dedicated lash prevention mechanisms, reducing overall system complexity.
Data Source
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AI summary
A system for actuating engine valve comprises a main valve actuation motion source configured to supply main valve actuation motions to the at least one engine valve via a main motion load path, and an auxiliary valve actuation motion source separate from the main valve actuation motion source and configured to supply complementary auxiliary valve actuation motions to the at least one engine valve via an auxiliary motion load path. A lost motion component is configured, in one state, to maintain lash between the auxiliary valve actuation motion source and the auxiliary motion load path or within the auxiliary motion load path and, in another state, to take up this lash. The auxiliary valve actuation motion source is further configured to supply at least one lash-prevention valve actuation motion that substantially matches at least one of the main valve actuation motions.