Variable Cam Timing Actuator Gain Control for VDE Transitions

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Solution Overview

Problem

Variable displacement internal combustion engines face challenges during transitions between displacement modes, as these transitions interact with the motive force used to move variable cam timing mechanisms, leading to inconsistent responses and stability issues.

Innovation Solution

A method is implemented to adjust the hydraulic system's gain and control signals based on cam timing feedback information, using different feedback control gains and null holding signals for VDE and non-VDE modes to coordinate variable displacement and cam timing operations, ensuring smooth transitions and improved stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If variable displacement transitions are implemented to improve fuel economy, then fuel efficiency is improved, but cam timing stability deteriorates during transitions

Engineering Contradiction:

Improvefuel economyVSAvoidcam timing stability

Core Design Contradiction:

Use of energy by moving objectVSStability of the object's composition

Solution Approach 1:

The patent applies dynamics by making the feedback control gain adjustable based on engine operating mode. The system switches between a first feedback control gain during VDE mode transitions and a second feedback control gain during non-VDE mode transitions. This dynamic adjustment of control parameters allows the system to maintain cam timing stability while enabling fuel economy improvements through variable displacement operation.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the control parameter (feedback control gain) based on the engine's displacement mode. By detecting whether the engine is in VDE or non-VDE mode and selecting appropriate gain values, the system optimizes cam timing control for each operating condition. This parameter change approach resolves the contradiction by adapting the control strategy to match the current operational state.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If constant cam position command is issued during VDE transitions, then cam position control is simplified, but VCT phaser position maintenance deteriorates

Engineering Contradiction:

Improvecontrol complexityVSAvoidVCT phaser position maintenance

Core Design Contradiction:

Device complexityVSStability of the object's composition

Solution Approach 1:

The system dynamically adjusts the feedback control gain based on the engine mode detected by the control system. During VDE transitions, a first feedback control gain is applied, while during non-VDE transitions, a second feedback control gain is applied. This dynamic adaptation allows the system to maintain VCT phaser position stability without increasing control complexity, as the gain adjustment is automatically managed by the mode-detecting control system.

Inventive Principle:

Principle #15Dynamics

3Speed

If higher feedback control gain is used during VDE operation, then cam timing response is improved, but controller stability deteriorates

Engineering Contradiction:

Improvecam timing response speedVSAvoidcontroller stability

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent implements parameter changes by selecting different feedback control gains based on the engine's displacement mode. The system uses a first feedback control gain during VDE mode and a second feedback control gain during non-VDE mode. This approach allows the controller to optimize response speed for each mode while maintaining stability, as the gain selection is adapted to the specific operational characteristics of each mode rather than using a fixed high gain that would cause instability.

Inventive Principle:

Principle #35Parameter changes

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

This approach allows for better control of variable cam timing, reducing phasing disturbances during cylinder activation/deactivation transitions and enhancing controller stability by compensating for differences in cam phasing system responses between VDE and non-VDE operations.

Implementation Method 1

a variable camshaft timing actuator coupled in a hydraulic system

Methodology Applied

Scientific EffectHydraulic actuation: Hydraulic Press

Data Source

PatentUS7835848B1Coordination of variable cam timing and variable displacement engine systems

Publication Date: 2010.11.16 FORD GLOBAL TECH LLC

AI summary

A method of controlling an engine with a first group of cylinders having selectively deactivatable cylinders valves and a variable camshaft timing actuator coupled in a hydraulic system is described. In one example, the method includes during a first mode where the first group of cylinders is activated to carry out combustion cycles, adjusting the hydraulic system with a first gain based on cam timing feedback information and/or maintaining a null position of the actuator by adjusting a control signal to the hydraulic system to within a first value range. During a second mode where the first group of cylinders is deactivated, the method includes adjusting the hydraulic system with a second gain based on cam timing feedback information, the second gain higher than the first gain and/or maintaining the null position of the actuator by adjusting the control signal to the hydraulic system to within a second value range.