Valve Actuation System With Segmented Rocker Arm
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Solution Overview
Problem
Existing valve actuation systems in internal combustion engines are limited in their ability to implement alternative actuation strategies, such as internal EGR and engine brake, which require different camshaft positioning, particularly during specific operating conditions like premature exhaust valve closure and compressed air discharge near the TDC point.
Innovation Solution
A valve actuation system that incorporates a first additional arm pivoting on one end of the rocker arm to contact valves and a second arm that interacts with a longitudinal element slidingly associated with the rocker arm, allowing for a different actuation strategy by intercepting the element with an actuator, enabling alternative valve control strategies like internal EGR or engine brake.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional rocker arm actuation system is used, then the structure is simple and easy to manufacture, but it cannot implement alternative actuation strategies such as internal EGR or engine brake
Solution Approach 1:
The rocker arm is segmented into multiple functional components: a first additional arm for normal valve actuation, a second additional arm for alternative actuation strategies, and a longitudinal element that can be intercepted by actuators. This segmentation allows each component to have specialized functions, enabling multiple actuation strategies while maintaining manageable complexity through modular design
Solution Approach 2:
The rocker arm assembly is designed with multi-functionality to perform both traditional valve actuation and alternative strategies. The first additional arm handles normal operation, while the second additional arm and longitudinal element enable internal EGR and engine brake functions. This universal design allows a single actuation system to serve multiple purposes across different operating conditions
2Adaptability or versatility
If the camshaft is moved axially to implement alternative strategies, then different actuation strategies can be realized, but the device complexity and size increase
Solution Approach 1:
Instead of moving the camshaft axially (one-dimensional movement), the invention uses a longitudinal element that can be intercepted by actuators, creating actuation in a different dimensional space. The second additional arm intercepts the longitudinal element at various points along its length, effectively providing multiple actuation positions without requiring camshaft displacement. This dimensional approach reduces overall system complexity while achieving the same functional goals
3Reliability
If larger hydraulic lash adjusters are used to ensure reliability, then valve clearance recovery is improved, but the weight and inertia of the actuation system increase
Solution Approach 1:
The system uses dynamic actuation through the second additional arm and actuator mechanism to control the longitudinal element. This dynamic approach allows precise control of valve timing and clearance without relying on oversized static hydraulic lash adjusters. The actuator can actively adjust the position of the longitudinal element, providing reliable valve clearance management with lighter components compared to passive hydraulic systems
Data Source
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AI summary
Valve actuation system of an internal combustion engine comprising at least one rocker arm (RA) hinged on a rocker arm shaft (BS) and having a first end (RA') facing at least one valve (V) to be actuated and a second end (RA") adapted to interact with a first actuation cam (CM1), the system comprising a first additional arm (AA) - a having a medial part (AAM) hinged in said first end (RA') of the rocker arm (RA), a first end (AA') adapted to directly contact said at least one valve (V), a second end (AA") opposite to said first end (AA'), in which a hydraulic lash adjuster (HLA) is interposed between said rocker arm (RA) and said second end (AA').