Dual Active Fuel Management Sequencing for Engine NVH Reduction

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Solution Overview

Problem

Conventional active fuel management systems in engines generate undesirable noise, vibration, and harshness (NVH) due to the sequence of deactivating and reactivating cylinders, particularly at low engine speeds, as they trap combusted charge, leading to high pressure/temperature conditions.

Innovation Solution

A dual active fuel management sequence is introduced, where at low engine speeds, intake valves are deactivated first, followed by exhaust valves, and at higher speeds, the conventional sequence of deactivating and reactivating exhaust valves before intake valves is maintained, allowing for reduced NVH and quicker torque delivery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If exhaust valves are deactivated before intake valves in conventional active fuel management, then cylinder deactivation is achieved, but high pressure/temperature trapped charge causes undesirable NVH at low engine speeds

Engineering Contradiction:

ImproveNVHVSAvoidcylinder deactivation sequence

Core Design Contradiction:

Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The patent inverts the conventional valve deactivation sequence by closing the intake valve before the exhaust valve during cylinder deactivation, and reopening them in reverse order during reactivation. This inversion prevents trapped charge from being compressed under high pressure/temperature conditions, thereby reducing NVH at low engine speeds while maintaining effective cylinder deactivation functionality

Inventive Principle:

Principle #13The other way round (Inversion)

2Productivity

If conventional valve deactivation sequence is used, then cylinder deactivation is achieved, but torque delivery is delayed due to trapped charge conditions

Engineering Contradiction:

Improvetorque delivery speedVSAvoidvalve sequencing control

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by closing the intake valve before the exhaust valve during deactivation, and reopening the exhaust valve before the intake valve during reactivation. This sequencing ensures that trapped charge mass and pressure/temperature are minimized before torque delivery is required, enabling faster torque response without excessive control complexity

Inventive Principle:

Principle #10Preliminary action

3Quantity of substance

If intake valves are deactivated first at low engine speeds, then trapped charge mass is minimized, but valve control complexity increases

Engineering Contradiction:

Improvetrapped charge massVSAvoidvalve control system

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The patent implements dynamic valve sequencing control that adapts to engine operating conditions. At low engine speeds, the intake valve is deactivated before the exhaust valve to minimize trapped charge mass. The control system dynamically adjusts the deactivation and reactivation sequence based on real-time engine speed and load conditions, optimizing trapped charge management while maintaining manageable control system complexity through condition-based logic

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS7757657B2Dual active fuel management sequencing

Publication Date: 2010.07.20 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

A system includes a cylinder selection module and a valve deactivation module. The cylinder selection module selects cylinders of an engine for active fuel management. The valve deactivation module deactivates intake valves of selected cylinders of the engine before deactivating exhaust valves of the selected cylinders when an engine speed of the engine is less than or equal to a predetermined speed.