Rocker Arm Additional Arm Valve Actuation System
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Solution Overview
Problem
Existing valve actuation systems in internal combustion engines face challenges with high compression forces on hydraulic lash adjusters (HLAs), leading to increased size and weight, which interfere with other mechanical components and result in unsatisfactory dynamic performance, especially during engine braking or high compression operations.
Innovation Solution
The introduction of an additional arm that pivots on the rocker arm, allowing the HLA to be housed closer to the rocker arm shaft, reducing the moment of inertia and scaling down axial forces, enabling smaller, lighter HLAs and improved dynamic performance by redistributing the lever ratio and positioning the HLA closer to the fulcrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the HLA is sized to withstand high compression forces during engine braking or high compression operations, then the reliability is improved, but the size and weight increase, interfering with other mechanical components
Solution Approach 1:
The system is divided into two separate actuation paths: a first camshaft for normal valve actuation and a second camshaft for high compression operations. This segmentation allows each camshaft to be optimized for its specific function, with the second camshaft engaging only when high compression forces are needed, thus avoiding the need for a continuously oversized HLA.
Solution Approach 2:
The system dynamically switches between two camshafts based on operating conditions. The second camshaft is positioned to engage with the rocker arm only during high compression operations or engine braking, allowing the HLA to be sized for normal operations while the dynamic engagement provides additional mechanical advantage when needed.
2Ease of operation
If the HLA is positioned at the end of the rocker arm to operate valves, then the ease of operation is improved, but the moment of inertia increases, resulting in unsatisfactory dynamic performance
Solution Approach 1:
An additional arm is introduced as an intermediary element between the HLA and the valve. This arm pivots on the rocker arm and allows the HLA to be positioned closer to the fulcrum, reducing the moment of inertia. The additional arm extends the lever arm length to maintain sufficient mechanical advantage for valve actuation despite the HLA's repositioning.
3Speed
If the HLA is positioned closer to the fulcrum to reduce moment of inertia, then the dynamic performance is improved, but the lever ratio is reduced, requiring larger forces
Solution Approach 1:
The solution adds a spatial dimension by introducing an additional arm that extends perpendicular to the rocker arm. This creates a two-dimensional lever system where the HLA acts on the additional arm, which in turn actuates the valve. This dimensional change allows the HLA to be positioned close to the fulcrum while maintaining sufficient force multiplication through the extended geometry of the additional arm.
4Device complexity
If a single camshaft is used for valve actuation, then the device complexity is reduced, but the adaptability to different operating conditions deteriorates
Solution Approach 1:
The dual camshaft system provides multi-functionality: the first camshaft handles normal operating conditions, while the second camshaft is specifically designed for high compression operations or engine braking. This universal design allows the valve actuation system to adapt to different operating regimes, with each camshaft optimized for its intended function.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution reduces the overall inertia of the actuation system, allows for smaller and cheaper HLAs, and enhances dynamic performance by minimizing interference with other components, enabling automatic recovery of valve clearance even under high compression conditions.
Implementation Method 1
hydraulic lash adjusters HLA, which consist of small hydraulic pistons which permit recovery of the clearance of the valves during the wear of the respective seats
Implementation Method 2
positioning the HLA closer to the fulcrum. The present invention also relates to a valve actuation of an internal combustion engine corresponding to the description in claim 1... an additional arm, which, with a first end contacts a valve or a valve group and with a second end, opposite the first, contacts the rocker arm via a HLA housed on said rocker arm
Implementation Method 3
scaling down axial forces, enabling smaller, lighter HLAs and improved dynamic performance by redistributing the lever ratio
Data Source
Figure 1
Figure 2
Figure 3~4
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 said first end (AA'), in which a hydraulic valve lifter (HLA) is interposed between said rocker arm (RA) and said second end (AA').