Engine Valve Control for Combustion Mode Transitions
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Internal combustion engines face challenges in controlling the transition between auto-ignition and spark-ignition combustion modes, leading to unstable combustion, emissions, and noise, due to discrete changes in valve lift profiles and limited control over engine air flow during mode transitions.
Innovation Solution
A method for controlling engine valves to smoothly transition between combustion modes by determining desired engine airflow and adjusting cylinder intake volume using a control scheme that manages variable valve lift and cam phasing, ensuring the transition stays within the authority of the engine valves, thereby maintaining robust combustion and low emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multi-step valve lift is used to transition between combustion modes, then combustion mode switching capability is improved, but combustion stability deteriorates due to discrete changes in valve lift profiles
Solution Approach 1:
The patent applies dynamics by transitioning from static discrete valve lift steps to dynamic continuous valve lift control. The cam phasing mechanism continuously adjusts valve timing and lift characteristics during mode transitions, enabling smooth adaptation between auto-ignition and spark-ignition combustion modes without abrupt changes that would destabilize combustion.
Solution Approach 2:
The patent utilizes parameter changes by modifying cam phasing angles to achieve continuous valve lift profiles. By varying the cam phase angle parameter, the system can smoothly transition valve lift characteristics between different combustion modes, maintaining combustion stability while enabling mode switching capability.
2Device complexity
If discrete valve lift steps are used, then device complexity is reduced, but control precision over engine air flow deteriorates
Solution Approach 1:
The patent applies another dimension by introducing cam phasing as an additional control dimension alongside valve lift. Instead of relying solely on discrete lift steps, the system uses continuous cam phase angle adjustments to achieve fine-grained control over valve timing and air flow, thereby improving control precision without significantly increasing mechanical complexity.
3Adaptability or versatility
If throttle is used to control air flow during mode transitions, then adaptability is improved, but energy efficiency deteriorates due to pumping losses
Solution Approach 1:
The patent applies mechanics substitution by replacing the throttle-based air flow control mechanism with cam phasing-based valve control. This substitution eliminates the need for throttle adjustments during mode transitions, thereby avoiding the pumping losses associated with throttle operation while maintaining adaptability in air flow management.
Data Source
AI summary
There is provided a method for controlling engine valves of an internal combustion engine adapted to selectively operate at one of a first open position and a second open position, including controlling engine operation during a transition from a first to a second combustion mode. The method comprises determining a desired engine airflow based upon an operator torque request. A cylinder intake volume is determined for the desired engine airflow when operating at the first open position. A control scheme is determined to control the engine valves to attain the cylinder intake volume for the desired engine airflow when operating at the second open position. The control scheme is executed and the engine valve is transitioned to the second open position when the cylinder intake volume to operate at the second open position is within a range of authority of the engine valves.