Intake CVVD and Exhaust CVVT Valve Timing Control
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Solution Overview
Problem
Existing engine technologies face challenges in simultaneously controlling valve duration and timing effectively, which affects fuel efficiency and power performance, especially under varying load conditions, and often require complex and costly continuous variable valve duration and timing systems.
Innovation Solution
A system and method that integrates continuous variable valve duration (CVVD) and continuous variable valve timing (CVVT) devices for both intake and exhaust valves, allowing for simultaneous control of valve duration and timing based on engine load and speed, with a controller adjusting opening and closing timings to optimize performance across different engine conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If continuous variable valve duration and timing devices are mounted on both intake and exhaust valves, then fuel efficiency and power performance are improved, but device complexity and cost increase
Solution Approach 1:
The system divides the valve control function into separate devices: CVVD device for duration control and CVVT device for timing control. Each device independently manages its specific function, allowing for optimized performance while reducing overall system complexity compared to a fully integrated variable duration and timing system.
Solution Approach 2:
The system implements continuous variable control for valve duration and timing parameters, allowing real-time adjustment based on engine operating conditions. This dynamic control enables the engine to optimize fuel efficiency under partial loads and power performance under high loads by continuously adapting valve characteristics to current operational demands.
2Manufacturing precision
If continuous variable valve duration device is mounted on exhaust valve, then valve control precision is improved, but device complexity and cost increase
Solution Approach 1:
The valve control system is segmented into separate functional devices: CVVD for duration and CVVT for timing. This segmentation allows precise control of valve duration at the exhaust valve without requiring a complex integrated system, as each device can be optimized for its specific function independently.
3Ease of manufacture
If fixed cam is used instead of continuous variable valve duration device at exhaust, then cost is reduced, but valve control flexibility decreases
Solution Approach 1:
The system uses a fixed cam for the exhaust valve duration control, eliminating the need for a complex CVVD device at the exhaust side. This segmentation approach allows the intake valve to have full variable duration control while the exhaust valve uses a simpler fixed cam, reducing overall system cost while maintaining adequate performance.
Solution Approach 2:
The system replaces the expensive continuous variable valve duration device at the exhaust valve with a simpler, more cost-effective fixed cam mechanism. This substitution maintains sufficient exhaust valve control for the application while significantly reducing system cost and complexity.
Data Source
AI summary
A method for controlling intake and exhaust valves of an engine includes: controlling, by an intake continuous variable valve timing (CVVT) device, opening and closing timings of the intake valve; controlling, by an exhaust CVVT device, opening and closing timing of the exhaust valve; determining, by a controller, first to fifth control regions based on engine load and speeds, and a target opening duration of the intake valve and target opening or target closing timings of the intake valve; modifying, by an intake continuous variable valve duration (CVVD) device, current opening and closing timings of the intake valve based on the target opening duration; and advancing or retarding, by the intake CVVD device, the current opening timing of the intake valve while simultaneously retarding or advancing the current closing timing of the intake valve by a predetermined value based on the target opening duration of the intake valve.