Switchable Roller Rocker Arms for Variable Valve Actuation
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Solution Overview
Problem
Existing engine valvetrains lack efficient mechanisms for switchable variable valve actuation, which can improve engine performance, fuel economy, and emissions.
Innovation Solution
A rocker arm assembly with a latching mechanism that selectively decouples and activates either the first or second roller assembly based on latching modes, using rocker body and roller body pins to transmit or absorb cam motions, enabling variable valve actuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed roller assembly is used in the rocker arm, then the structure is simple and reliable, but the valve actuation cannot be varied to improve engine performance and fuel economy
Solution Approach 1:
The rocker arm assembly incorporates switchable roller assemblies that can dynamically change their operational state between active and inactive positions. The roller assemblies are pivotally connected to the rocker arm body and can be selectively positioned using a latching mechanism, allowing the system to adapt between different valve actuation modes (variable valve lift and variable valve timing) rather than being fixed in a single configuration
Solution Approach 2:
The roller assembly is divided into multiple independent roller elements (first roller assembly with first roller, second roller assembly with second roller) that can be independently controlled. Each roller assembly can be selectively activated or deactivated through the latching mechanism, allowing partial functionality to be maintained while other segments are switched off, thereby achieving adaptability without requiring complete system redesign
2Productivity
If switchable roller assemblies are added to enable variable valve actuation, then engine performance and fuel economy are improved, but the device complexity increases
Solution Approach 1:
The rocker arm assembly is designed to perform multiple functions through its switchable roller assemblies. The same roller assembly structure serves both as a simple follower in fixed valve lift mode and as a controllable element for variable valve lift and variable valve timing modes. The latching mechanism integrates with the existing rocker arm body rather than requiring separate control systems, allowing one mechanism to achieve multiple valve actuation functions
Solution Approach 2:
The latching mechanism is integrated within the rocker arm body structure, with the latch member and actuator nested within the existing assembly. The roller assemblies are pivotally connected to the rocker arm body and can be contained within or integrated into the rocker arm housing, allowing the switching mechanism to be embedded within the existing structure rather than adding external components
Data Source
AI summary
A rocker arm assembly capable of switchably deactivating a roller assembly includes a valve end and a cam end having first and second roller assemblies, and a latching mechanism. The latching mechanism includes rocker body pins and roller body pins. The rocker body pins include first and second end pins and a connection pin, each pin provided within a rocker arm body along a latching axis. The roller body pins include first and second locking pins, each roller body pin provided within a respective roller assembly. In a first latching mode, the first roller assembly is deactivated and the second roller assembly is activated. In a second latching mode, the second roller assembly is deactivated and the first roller assembly is activated.