Two-Step Rocker Arm Assembly with Translatable Shaft
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Solution Overview
Problem
Prior art two-step rocker arm assemblies for internal combustion engines are complex in design and manufacturing, requiring distinct cam profiles and multiple components to achieve adjustable valve lift modes, which complicates the valvetrain's adjustability and efficiency.
Innovation Solution
A two-step rocker arm assembly with a C-shaped opening and a selectively translatable shaft member, coupled with spring levers and a hydraulically actuated latch assembly, allows for unitary movement and adjustable valve lift modes by guiding roller assemblies between high-lift and low-lift cams, simplifying the design and reducing manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If prior art two-step rocker arm assemblies use distinct cam profiles and multiple components to achieve adjustable valve lift modes, then the valvetrain's adjustability is improved, but the design complexity and manufacturing complexity increase
Solution Approach 1:
The patent merges the inner and outer rocker arm assemblies into a single integrated rocker arm structure. The shaft member is integrated within the rocker arm, and the coupling lever is directly mounted on the rocker arm body. This consolidation reduces the number of separate components while maintaining the two-step valve lift functionality through the integrated shaft and coupling mechanism.
Solution Approach 2:
The rocker arm assembly is designed to perform multiple functions: it provides both low-lift and high-lift valve operation modes, incorporates the shaft translation mechanism, includes the coupling lever for mode switching, and integrates the roller assemblies all within a single multi-functional component structure, eliminating the need for separate dedicated components for each function.
2Adaptability or versatility
If prior art two-step rocker arm assemblies use distinct cam profiles and multiple components, then adjustable valve lift modes are achieved, but manufacturing complexity increases
Solution Approach 1:
The patent combines multiple previously separate components (inner rocker arm, outer rocker arm, shaft, coupling lever) into a single integrated rocker arm assembly. This reduction in component count directly simplifies manufacturing processes, assembly operations, and quality control while preserving the adjustable valve lift capability through the integrated shaft translation mechanism.
3Ease of operation
If a shaft member is selectively translatable within a C-shaped opening to guide roller assemblies, then unitary movement and mode transitions are enabled, but the mechanism complexity increases
Solution Approach 1:
The shaft member is designed to be selectively translatable rather than fixed, allowing it to dynamically shift position within the C-shaped opening to enable transitions between low-lift and high-lift modes. The coupling lever provides dynamic engagement and disengagement capability, allowing the shaft to move freely in one mode while being constrained in the other mode, creating a dynamic mechanism that adapts its constraints based on operational requirements.
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
The solution enables efficient and adjustable valve lift operation with reduced manufacturing complexity, allowing for seamless transitions between high-lift and low-lift modes, enhancing the valvetrain's adjustability and operational efficiency.
Implementation Method 1
a first spring member may be disposed between the first spring lever and the arm member to bias the shaft member with respect to the arm member
Implementation Method 2
A first roller assembly rotatably mounted with respect to the arm member... A second roller assembly, such as a roller bearing
Implementation Method 3
A latch assembly, having a hydraulically actuated pin, may be provided to selectively engage the coupling lever to selectively retain the shaft member
Data Source
AI summary
A two-step rocker arm assembly is provided having an arm member and a first roller assembly rotatably mounted with respect to the arm member and defining a generally C-shaped opening. A shaft member rotatably supports a second and a third roller assembly. The shaft member extends through the generally C-shaped opening and is selectively translatable therein to guide the second and third roller assemblies with respect to the arm member. A coupling lever is mounted with respect to the shaft member and is operable to selectively retain the shaft member with respect to the arm member for unitary movement therewith.