Variable Valve Lift Transition Control for Switching Roller Finger Follower Wear

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Solution Overview

Problem

Variable valve actuation systems face issues with response time variability, leading to unscheduled disengagement of Switching Roller Finger Follower arms, causing engine valve drop and accelerated wear due to limited time for switching between high-lift and low-lift valve events.

Innovation Solution

A system with a delay module that estimates total delay in the variable valve lift system, adjusting crankshaft angular positions and controlling throttle position, spark timing, and camshaft phaser movement to manage transitions between valve profiles, ensuring proper engagement and reducing wear.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the control valve causes a fluid pressure change in a lifter fluid gallery to occur too soon relative to a valve lift curve, then the valve event profile can be changed, but the SRFF arm lock pin may only partially engage and then disengage after the valve has started lifting, causing unscheduled disengagement and accelerated wear

Engineering Contradiction:

Improvevalve event profile switching capabilityVSAvoidSRFF arm lock pin engagement reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The system performs preliminary actions by adjusting engine operating parameters (throttle position, spark timing, camshaft phaser movement) before the valve profile transition occurs. This prepares the engine state in advance to accommodate the transition, ensuring the SRFF arm lock pin has sufficient time to fully engage before valve lift changes, thereby preventing unscheduled disengagement while maintaining the ability to switch between valve event profiles

Inventive Principle:

Principle #10Preliminary action

2Speed

If the control valve causes a fluid pressure change too early, then valve profile transition can be initiated, but the limited time available for switching causes the SRFF arm lock pin to partially engage and disengage, leading to valve drop and accelerated wear

Engineering Contradiction:

Improvevalve profile transition speedVSAvoidaccelerated wear and valve damage

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The system executes preliminary adjustments to engine parameters (throttle position, spark timing, camshaft phaser movement) before initiating the valve profile transition. This ensures the engine is properly prepared, allowing sufficient time for the SRFF arm lock pin to complete engagement without causing accelerated wear or valve damage, while still enabling timely profile transitions

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system provides a cushioning effect by coordinating parameter adjustments in advance of the valve profile transition. This cushioning approach ensures that the SRFF arm lock pin engagement is not rushed, preventing harmful effects such as partial engagement, unscheduled disengagement, and accelerated wear that would otherwise occur during rapid transitions

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS8056516B2Variable valve lift transition control methods and systems

Publication Date: 2011.11.15 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

A system for controlling a variable valve lift system of an engine comprises a delay module that estimates a total delay based on at least one of a measured and an estimated delay of the variable valve lift system. A variable valve control module commands one of a first transition from a variable valve low-lift profile to a variable valve high-lift profile and a second transition from a variable valve high-lift profile to a variable valve low-lift profile based on the total delay.