CVVD Startup Control via Dual Duration Delay
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Solution Overview
Problem
Continuously variable valve duration (CVVD) systems face challenges in maintaining engine startup stability due to variations in fuel environments and driving conditions, particularly when switching from startup to driving regions, which can lead to engine RPM variations and reduced performance.
Innovation Solution
Implementing a dual duration control method that includes a duration time delay control, where the CVVD system switches from startup duration to driving region duration after a predetermined time, using a CVVD controller with dual maps to manage engine RPM variations by distinguishing between normal and ISG startups and applying appropriate delay times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the CVVD system switches from startup duration to driving region duration after engine startup, then the engine can operate efficiently in driving conditions, but engine RPM variations occur during the transition
Solution Approach 1:
The patent applies a predetermined delay time after engine startup before switching from startup duration to driving region duration. This preliminary waiting period allows the engine to stabilize its RPM after startup, preventing RPM variations during the transition. The delay time is set in advance based on expected engine stabilization behavior, ensuring smooth transition without disrupting engine operation.
2Device complexity
If the CVVD system uses a single duration configuration for all startup conditions, then the system is simple to control, but startup stability deteriorates under varying fuel environments and driving conditions
Solution Approach 1:
The patent implements dynamic duration configuration that adapts to different startup conditions. The system distinguishes between normal startup and ISG (idle stop and go) startup modes, and selects appropriate duration configurations (startup duration or driving region duration) based on the detected startup type and elapsed time. This dynamic adaptation ensures reliable startup stability across varying fuel environments and driving conditions while maintaining manageable control complexity through structured decision logic.
3Speed
If the CVVD system applies driving region duration immediately after startup, then the system responds quickly to driver demands, but startup stability is compromised due to premature duration switching
Solution Approach 1:
The system prepares by establishing a predetermined delay time period after startup before allowing transition to driving region duration. This preliminary timing mechanism ensures the engine completes its startup stabilization process before the duration switch occurs, preventing premature switching that would compromise stability while still enabling relatively quick transition once the delay period expires.
Data Source
AI summary
A method for continuous variable valve duration (CVVD) startup control may include a duration time delay control to prevent an engine revolutions per minute (RPM) variation through applying of a delay time with respect to a startup duration in the case where the startup duration at an initial startup is switched to a driving region duration after the startup lapse by a CVVD controller.