CVVD Engine Control for Low-Speed Torque and Fuel Efficiency
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Solution Overview
Problem
Existing engine systems with continuous variable valve lift (CVVL) and variable valve timing (CVVT) are complex and costly, and there is a need for a method to improve acceleration performance and fuel consumption, particularly at low engine speeds.
Innovation Solution
A method and apparatus using a continuous variable valve duration (CVVD) system that detects engine speed and accelerator pedal position to increase valve overlap, advancing ignition timing and controlling air-fuel ratio to be lean, thereby improving torque responsiveness and fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If general CVVL or CVVT apparatus are used to achieve optimal valve operation depending on engine speed, then valve timing control is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines CVVL and CVVT functions into a single CVVD apparatus that controls both valve lift and valve timing simultaneously. This merging of functions reduces the number of separate apparatuses needed while achieving comprehensive valve operation control across different engine speeds
Solution Approach 2:
The CVVD apparatus is designed to perform multiple functions - controlling valve lift duration, valve timing, and valve overlap - within a single system. This multi-functionality replaces what would traditionally require separate CVVL and CVVT apparatuses, reducing overall system complexity
2Power
If ignition timing is advanced to improve acceleration performance after increasing valve overlap, then torque responsiveness improves, but knocking may occur
Solution Approach 1:
The control system continuously monitors engine operation parameters and adjusts ignition timing based on feedback from knock detection. When valve overlap is increased, the system advances ignition timing to improve torque, but automatically retards timing if knocking is detected, creating a closed-loop control that balances performance and reliability
Solution Approach 2:
The system dynamically adjusts ignition timing based on real-time engine conditions and valve overlap settings. Rather than using a fixed timing map, the ignition timing is continuously optimized according to the current valve duration and engine load, allowing the system to extract maximum performance without inducing knocking
Data Source
AI summary
A method of controlling an engine system may include: method of controlling an engine system including a continuous variable valve duration (CVVD) apparatus, the method including: detecting data for controlling the engine system; determining whether a speed of an engine is less than a predetermined speed; determining whether a position value of an accelerator pedal is greater than a predetermined position value when the rotation speed of the engine is less than the predetermined speed; operating the CVVD apparatus to increase a valve overlap when the position value of the accelerator pedal is greater than the predetermined position value; and performing a knock control after the valve overlap is increased.