Rocker Arm Cylinder Deactivation via Segmented Inner Outer Arms
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Solution Overview
Problem
Current cylinder deactivation and variable valve lift techniques in internal combustion engines lack efficiency and flexibility in dynamically changing power characteristics and fuel economy.
Innovation Solution
A rocker arm apparatus with an inner and outer arm portion, pivotally connected by a shaft, utilizing rolling contact bearings with the camshaft and a lost motion spring, allowing for either cylinder deactivation or two-step valve actuation through a hydraulic system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional single-stage rocker arm is used, then the structure is simple, but the ability to dynamically change valve lift and deactivate cylinders is limited
Solution Approach 1:
The rocker arm is divided into an inner arm portion and an outer arm portion that can rotate relative to each other about a shaft. This segmentation allows the inner arm to be selectively decoupled from the outer arm, enabling cylinder deactivation while maintaining a relatively simple overall structure.
Solution Approach 2:
The rocker arm transitions from a static single-stage structure to a dynamic two-stage structure where the inner arm portion can rotate relative to the outer arm portion. This dynamic capability enables the system to switch between active and deactivated states, providing adaptability without excessive complexity.
2Loss of energy
If cylinder deactivation is implemented, then fuel economy improves, but the mechanism complexity increases
Solution Approach 1:
The inner arm portion is extracted as a separate rotatable component from the traditional single rocker arm. This extraction allows the deactivation function to be isolated to a specific component, making the overall mechanism easier to understand and maintain while achieving fuel economy benefits.
Solution Approach 2:
The inner arm portion is nested within the outer arm portion, with the inner arm positioned inside the U-shaped outer arm. This nesting arrangement compactly houses the deactivation mechanism within the existing rocker arm footprint, minimizing space requirements and reducing overall complexity.
3Adaptability or versatility
If variable valve lift is achieved through multiple stages, then power characteristics can be dynamically changed, but the rocker arm structure becomes more complex
Solution Approach 1:
The two-stage rocker arm mechanism serves multiple functions: it can provide full valve lift when the inner and outer arms are locked together, and it can provide reduced valve lift or complete deactivation when the inner arm rotates relative to the outer arm. This multi-functionality achieves variable valve lift capability without requiring separate mechanisms for each 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
Enables efficient cylinder deactivation and dynamic valve lift adjustments, improving fuel economy and power characteristics by allowing simultaneous valve actuation and switching between valve profiles.
Implementation Method 1
a lost motion spring positioned between the at least one inner arm portion and the at least one outer arm portion near a hydraulic lash adjuster end of the rocker arm apparatus. The lost motion spring resists rotation of the at least one inner arm portion relative to the at least one outer arm portion.
Implementation Method 2
a first bearing attached to the at least one inner arm portion to provide rolling contact with a lobe of a cam shaft
Data Source
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AI summary
A rocker arm assembly to provide either cylinder deactivation or reduced valve lift. The rocker arm assembly includes inner and outer portions that are rotatably connected to one another. In one state, the inner and outer portions are locked together to provide traditional valve lift. In a second state, the inner portion is allowed to rotate relative to the outer portion to deactivate the cylinder or provide reduced valve lift. Bearings on both the inner and outer portions provide rolling contact with corresponding cam shaft features. A hydraulic system provides transition between the first and second states.