Two Step Rocker Arm Side By Side Roller Configuration
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Solution Overview
Problem
Existing switching rocker arm technologies for internal combustion engines lack efficient mechanisms for controlling valve actuation between latched and unlatched states, leading to suboptimal fuel economy and emission reduction.
Innovation Solution
A rocker arm assembly with an outer and inner rocker arm, featuring a lash adjuster and oil control valve system that provides hydraulic fluid to actuate the inner rocker arm between latched and unlatched positions, allowing for asymmetric loading and control of valve actuation through a dual or single lash adjuster configuration, enabling four lift options and reduced complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If switching rocker arm technology is used to control valve actuation between latched and unlatched states, then fuel economy and emission reduction are improved, but the mechanism complexity for switching modes increases
Solution Approach 1:
The rocker arm is divided into inner and outer segments that can move independently. The inner rocker arm can be latched to the outer rocker arm or moved independently, allowing discrete control of valve lift patterns. This segmentation enables multiple valve actuation modes (latched, unlatched, intermediate positions) without requiring a completely complex switching mechanism, as each segment can be controlled separately through the hydraulic system.
Solution Approach 2:
The rocker arm system transitions from a static single-position design to a dynamic multi-position system. The inner rocker arm can dynamically adjust its position relative to the outer rocker arm through hydraulic actuation, enabling real-time switching between latched and unlatched states. This dynamic capability allows the system to adapt valve lift characteristics during engine operation, improving fuel economy and emissions without requiring multiple fixed rocker arm assemblies.
2Measurement precision
If discrete variable valve lift control is implemented through switching rocker arm modes, then valve actuation precision is improved, but the number of components and system complexity increase
Solution Approach 1:
The single rocker arm assembly performs multiple functions by combining inner and outer rocker arm segments. The same physical component can operate in latched mode for high-lift operation, unlatched mode for low-lift operation, or intermediate positions for variable lift control. This multi-functionality eliminates the need for separate rocker arms for different valve lift patterns, reducing component count while maintaining precise valve actuation control through hydraulic positioning of the inner segment.
3Productivity
If inner and outer rocker arms provide asymmetric loading with offset axes, then engine performance across various speeds is improved, but manufacturing precision requirements increase
Solution Approach 1:
The inner and outer rocker arms are designed with asymmetric geometry and offset rotation axes. The inner rocker arm rotates about an axis offset from the outer rocker arm's axis, creating asymmetric loading patterns during operation. This asymmetry allows optimization of valve lift profiles for different engine speeds and loads, improving overall engine performance. The offset axes enable the inner segment to provide additional mechanical leverage or reduce lateral forces depending on the operating mode, enhancing efficiency across the engine's operating range.
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 enhances fuel economy and emission reduction by providing precise control over valve actuation, reducing side-to-side rocking and balancing loading, thereby improving engine performance across various speeds.
Implementation Method 1
a lash adjuster (HLA) that cooperates with a first oil control valve (OCV) to provide hydraulic fluid to the rocker arm assembly and actuate a first latch associated with the inner rocker arm
Data Source
AI summary
A rocker arm assembly constructed in accordance to one example of the present disclosure includes an outer rocker arm and an inner rocker arm. The outer rocker arm has a first roller configuration that rotates around a first axis. The inner rocker arm has a second roller configuration that rotates around a second axis. The inner rocker arm is configured to move between a latched and unlatched position relative to the outer rocker arm. One of the first and second axes is positioned for alignment over an engine valve. The other of the first and second axes is offset from the engine valve.