CVVD Engine Valve Timing Control via Region-Based Strategy

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Solution Overview

Problem

Existing engine technologies face challenges in simultaneously controlling the duration and timing of valves in continuous variable valve duration (CVVD) and continuous variable valve timing (CVVT) systems, particularly in turbo engine vehicles, which affects engine performance and efficiency.

Innovation Solution

A system and method that independently control the opening and closing timing of intake and exhaust valves using a CVVD device and CVVT device, classifying control regions based on engine speed and load to apply maximum duration, limit valve overlap, advance timing, and optimize valve positions to improve combustion stability and efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If CVVD and CVVT devices are combined to simultaneously control valve duration and timing, then engine performance and efficiency are improved, but device complexity increases

Engineering Contradiction:

Improveengine performanceVSAvoidvalve control system complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent combines CVVD and CVVT control systems into a unified valve control architecture where the intake valve is controlled by both duration and timing mechanisms while the exhaust valve uses duration control only. This merging approach enables simultaneous optimization of both valve parameters to improve engine performance across different operating conditions.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent segments the valve control system by applying different control strategies to intake and exhaust valves. The intake valve receives full CVVD+CVVT control for maximum flexibility, while the exhaust valve uses simplified CVVD control, thereby reducing overall system complexity while maintaining performance benefits.

Inventive Principle:

Principle #1Segmentation

2Use of energy by moving object

If maximum valve duration is applied to intake valve, then fuel efficiency under partial load is improved, but power performance under high load may be compromised

Engineering Contradiction:

Improvefuel efficiencyVSAvoidpower performance

Core Design Contradiction:

Use of energy by moving objectVSPower

Solution Approach 1:

The patent implements dynamic valve duration and timing control that adapts to different engine operating conditions. Under partial load conditions, maximum valve duration is applied to improve fuel efficiency, while under high load conditions, the system adjusts valve timing and duration to optimize power output, thereby resolving the trade-off between efficiency and performance.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes valve operation parameters (duration and timing) based on engine load and speed conditions. By dynamically adjusting these parameters, the system achieves optimal fuel efficiency during partial load operation while maintaining sufficient power performance during high load operation.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If valve timing is advanced to improve combustion stability, then combustion efficiency is improved, but mechanical stress on valve train increases

Engineering Contradiction:

Improvecombustion stabilityVSAvoidvalve train stress

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent applies preliminary timing advance to the intake valve closing event, positioning it optimally before top dead center to ensure complete combustion before the power stroke begins. This preliminary action improves combustion stability and efficiency while the system monitors and manages valve train stresses through controlled timing limits.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS9889838B2Method for controlling of valve timing of continuous variable valve duration engine

Publication Date: 2018.02.13 HYUNDAI MOTOR CO LTD

AI summary

A method for controlling valve timing for an engine includes: classifying a plurality of control regions depending on an engine speed and an engine load; applying a maximum duration to an intake valve and controlling an exhaust valve to limit a valve overlap in a first region; controlling the intake valve and the exhaust valve to maintain the maximum duration in a second region; advancing an intake valve closing (IVC) timing and an exhaust valve closing (EVC) timing in a third region; approaching the IVC timing to a bottom dead center (BDC) in a fourth region; controlling a throttle valve to be fully opened, advancing an intake valve opening (IVO) timing before a top dead center (TDC), and controlling the IVC timing to be a predetermined value after the BDC in a fifth region; and controlling the throttle valve to be fully opened and advancing the IVC timing in a sixth region.