CVVD Engine Valve Timing Control via Exhaust-Side Segmentation
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Solution Overview
Problem
Existing engine systems with continuous variable valve duration (CVVD) and continuous variable valve timing (CVVT) devices struggle to simultaneously control valve duration and timing effectively across varying engine speed and load conditions, leading to inefficiencies in fuel efficiency and power performance.
Innovation Solution
A system and method that independently control the opening and closing timing of intake and exhaust valves using a CVVD device on the intake side and a two-stage VVD and CVVT device on the exhaust side, classifying control regions based on engine speed and load to apply optimal valve durations and timings, thereby maintaining valve overlap and improving combustion stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a continuous variable valve duration (CVVD) device and continuous variable valve timing (CVVT) device are equipped on both intake and exhaust valves to independently control valve duration and timing, then fuel efficiency and power performance are improved across varying engine conditions, but device complexity and manufacturing cost increase
Solution Approach 1:
The valve control system is segmented into different configurations: a first configuration with CVVD and CVVT devices on both intake and exhaust valves for optimal performance, and a second configuration omitting the intake CVVD device to reduce complexity and cost. This segmentation allows selection based on specific application requirements.
Solution Approach 2:
Different valve control configurations are applied to different valves based on local requirements: the exhaust valve receives advanced control devices (CVVD and CVVT) to optimize exhaust gas flow and combustion, while the intake valve may omit the CVVD device in cost-sensitive applications, as the exhaust side control provides sufficient benefit for fuel efficiency and power performance.
2Ease of manufacture
If the intake CVVD device is omitted and only a two-stage VVD device is used at the exhaust side, then manufacturing cost is reduced, but valve control flexibility decreases
Solution Approach 1:
The intake CVVD device is extracted (removed) from the system to reduce manufacturing cost. The patent demonstrates that the exhaust side CVVD and CVVT devices, combined with the two-stage VVD device, can provide sufficient valve control flexibility for most operating conditions without the intake CVVD device, thereby achieving cost reduction while maintaining adequate adaptability.
Data Source
AI summary
A method for controlling valve timing is provided for a turbo engine provided with a continuous variable valve duration (CVVD) device, a two stage variable valve duration device (VVD) and a continuous variable valve timing (CVVT) device. The method includes: classifying control regions; retarding an intake valve closing (IVC) timing and controlling an exhaust valve to limit a valve overlap in a first region; applying a maximum duration to an intake valve and applying a long duration to the exhaust valve in a second region; applying the long duration to the exhaust valve and advancing the IVC timing in a third region; controlling a throttle valve to be fully opened, applying a short duration to the exhaust valve and retarding an exhaust valve opening (EVO) timing in a fourth region; and controlling the throttle valve to be fully, applying the long duration to the exhaust valve and retarding the IVC timing in a fifth region.