Deactivating Rocker Arm With Telescopic Latch Pin Assembly
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Solution Overview
Problem
Deactivating rocker arms in internal combustion engines face challenges in returning to an activated state from a deactivated state, especially during excessive lash adjuster pump-up, as they may not be in a position to readily achieve the required configuration for reactivation.
Innovation Solution
A rocker arm assembly with a latch pin assembly that includes primary and secondary latch pin assemblies, which telescope and are biased by oil pressure to switch between full lift, partial lift, and lost motion lift modes, allowing the rocker arm to pivot and control valve lift profiles effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a deactivating rocker arm uses a mechanical latch pin mechanism to achieve selective activation and deactivation, then the rocker arm can exhibit lost motion movement in deactivated state, but the rocker arm may not be in a position to readily achieve the required configuration for reactivation during excessive lash adjuster pump-up
Solution Approach 1:
The patent employs a nested latch pin assembly where a first latch pin is disposed within a second latch pin, and both are telescopic. This nested configuration allows compact storage of multiple latch functions within the same space, enabling the rocker arm to maintain multiple deactivated states (full, partial, zero lift) while ensuring at least one latch pin remains positioned to facilitate reactivation during excessive lash adjuster pump-up conditions.
2Adaptability or versatility
If the latch pin assembly uses telescopic pins with biasing members and oil control cavities to control valve lift profiles, then the rocker arm can switch among full lift, partial lift, and lost motion modes, but the mechanism complexity increases
Solution Approach 1:
The patent employs a nested latch pin assembly where a first latch pin is disposed within a second latch pin, and both are telescopic. This nested configuration allows compact storage of multiple latch functions within the same space, enabling the rocker arm to maintain multiple deactivated states (full, partial, zero lift) while ensuring at least one latch pin remains positioned to facilitate reactivation during excessive lash adjuster pump-up conditions.
Solution Approach 2:
The patent utilizes hydraulic control through oil control cavities and biasing members to actuate the telescopic latch pins. Pressurized oil controls the extension and retraction of the latch pins, enabling seamless transitions between full lift, partial lift, and lost motion modes. This hydraulic mechanism replaces complex mechanical linkages with fluid-powered actuation, achieving versatile valve lift control while managing system complexity.
3Stability of the object's composition
If the rocker arm assembly uses a rim around the primary latch pin assembly to constrain movement, then the latch pin can telescope out into the rim for controlled movement, but the structural complexity increases
Solution Approach 1:
The patent employs a nested latch pin assembly where a first latch pin is disposed within a second latch pin, and both are telescopic. This nested configuration allows compact storage of multiple latch functions within the same space, enabling the rocker arm to maintain multiple deactivated states (full, partial, zero lift) while ensuring at least one latch pin remains positioned to facilitate reactivation during excessive lash adjuster pump-up conditions.
Solution Approach 2:
The patent introduces a rim structure that extends radially outward from the primary latch pin assembly, creating a new dimensional constraint. This rim provides a physical boundary that guides and constrains the telescopic movement of the latch pins in a radial direction, ensuring controlled movement while maintaining structural stability. The rim transforms the constraint from a linear to a radial geometric dimension.
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 seamless transition between different lift modes, including full lift, partial lift, and lost motion, enhancing the operational flexibility and efficiency of the rocker arm assembly by controlling valve lift profiles and maintaining engine performance.
Implementation Method 1
The valve side body comprises an oil channel configured to supply oil pressure to the primary oil control cavity. A first biasing member is configured to bias the second primary pin out of the first primary pin.
Implementation Method 2
A first biasing member is configured to bias the second primary pin out of the first primary pin. A second biasing member is configured to bias the first secondary pin out of the cam side rocker arm portion.
Data Source
AI summary
A rocker arm assembly comprises a valve side rocker arm portion, a cam side rocker arm portion configured to selectively rotate relative to the valve side rocker arm portion, and a latch pin assembly disposed in the valve side rocker arm portion and in the cam side rocker arm portion. Portions of the latch pin assembly are configured to move so that when the cam side rocker arm portion selectively rotates, the valve side rocker arm portion switches among a full lift mode, a partial lift mode, and a lost motion lift mode.