CVVD Engine Valve Timing Control via Region-Based Overlap Optimization
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Solution Overview
Problem
Existing engine systems with continuous variable valve duration (CVVD) and continuous variable valve timing (CVVT) devices face challenges in simultaneously controlling valve duration and timing effectively across varying engine speeds and loads, affecting fuel efficiency and power performance.
Innovation Solution
A system and method that classify engine control regions based on speed and load to control intake and exhaust valve timing and duration using a combination of CVVD and CVVT devices, with a controller managing valve operations to optimize valve overlap, duration, and timing, including fixing intake valve timings, reducing exhaust valve closing timing retardation, and adjusting throttle valve positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If CVVD and CVVT devices are mounted on both intake and exhaust to control valve duration and timing, then fuel efficiency and power performance are improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines CVVD and CVVT devices on the intake side with a fixed cam on the exhaust side, merging the control functions to achieve both fuel efficiency and power performance improvement without requiring full dual-sided variable duration control
Solution Approach 2:
The patent applies different control strategies to different sides: variable duration control (CVVD) is applied locally to the intake valve while the exhaust valve uses fixed duration with variable timing (CVVT only), allowing optimized control where needed without unnecessary complexity elsewhere
2Productivity
If maximum duration is applied to intake valve in first control region, then fuel efficiency under partial load is improved, but valve overlap control becomes more difficult
Solution Approach 1:
The controller uses feedback from engine operating conditions (speed and load sensors) to dynamically adjust valve timing and duration parameters, automatically optimizing valve overlap control while maintaining maximum duration for fuel efficiency in the first control region
3Power
If exhaust valve closing timing is retarded to control valve overlap in second control region, then power performance is improved, but combustion stability may be affected
Solution Approach 1:
The controller dynamically changes the exhaust valve closing timing parameter based on detected engine operating conditions, retarding the timing in the second control region to improve power performance while monitoring and adjusting to maintain combustion stability
Data Source
AI summary
The present disclosure provides a system and a method for controlling valve timing of continuous variable valve duration engine. The method includes: classifying control regions depending on engine speed and engine load; applying a maximum duration to an intake valve and controlling valve overlap between the intake valve and an exhaust valve in a first control region; applying the maximum duration to the intake valve and reducing the valve overlap by using exhaust valve closing (EVC) timing in a second control region; advancing intake valve closing (IVC) timing according to an increase of the engine load in a third control region; controlling a throttle valve to be fully opened and controlling the EVC timing to an angle after top dead center in a fourth control region; and controlling the throttle valve to be fully opened and controlling the IVC timing according to the engine speed in a fifth control region.