Valve Travel Switching Control for Turbocharged Engine Efficiency
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Solution Overview
Problem
Modern internal combustion engines with turbochargers and valve travel actuators face limitations in achieving desired power and fuel efficiency due to physically determined limits and restrictions from components like exhaust-gas turbochargers with reduced efficiency, making it challenging to harmonize high power with low fuel consumption.
Innovation Solution
A method for valve travel switching control in internal combustion engines that determines the current sensitivity of charge pressure and adjusts valve travel based on the wastegate valve position to predict whether charge pressure changes or valve travel modifications are necessary to achieve a desired operating point, allowing for extended operating ranges without considering limiting components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the valve travel is reduced to improve fuel consumption, then the specific fuel consumption decreases, but the power output is limited and the operating range is restricted
Solution Approach 1:
The valve travel is made dynamically switchable between different positions (fully open, partially open, closed) based on operating conditions. The control unit switches between valve travel positions to optimize between fuel consumption and power output, allowing the engine to adapt to different driving requirements and extend the operating range where reduced valve travel can be used.
Solution Approach 2:
The system changes the valve travel parameter (opening cross-section integral over crank angle) to optimize engine performance. By adjusting the valve travel parameter, the engine can operate at smaller valve travels for fuel efficiency while maintaining the ability to switch to larger valve travels when power is needed, effectively managing the trade-off between fuel consumption and power output.
2Reliability
If the switching threshold is determined by applicative measures to ensure reliable achievement of desired operating points, then the reliability is improved, but the operating range with small valve travel is limited
Solution Approach 1:
The control unit uses feedback from the actual operating point (actual cylinder air mass, actual charge pressure) to determine whether to switch valve travel. By continuously monitoring these parameters and comparing them with desired values, the system reliably determines when switching is necessary while maximizing the operating range where small valve travel can be maintained.
Solution Approach 2:
The system performs preliminary estimation of the maximum charge pressure that can be achieved with the current valve travel and wastegate valve position. This preliminary assessment allows the control unit to predict whether the desired operating point can be achieved without switching, thereby extending the operating range with small valve travel while maintaining reliability.
3Use of energy by moving object
If the charge pressure is increased to maintain cylinder air mass with reduced valve travel, then the fuel efficiency is improved, but the charge pressure buildup capability is limited by the turbocharger
Solution Approach 1:
The wastegate valve serves as an intermediary element to control the charge pressure. By adjusting the wastegate valve position, the system can influence the charge pressure buildup independently of the valve travel setting, enabling better fuel efficiency at reduced valve travels while maintaining the ability to achieve desired charge pressures when needed.
Data Source
AI summary
Embodiments of the present disclosure relate to a method and device for valve travel switching control of an internal combustion engine supercharged by an exhaust-gas turbocharger having a wastegate valve. This valve travel switching control includes: determining the current sensitivity of the charge pressure at a current operating point, at which a current valve travel, a current wastegate valve position and a current charge pressure are present, to changes in the wastegate valve position; determining the minimum valve travel necessary to set a desired operating point, taking into account the determined current sensitivity of the charge pressure; and switching the valve travel if the minimum valve travel necessary to set the internal combustion engine to an extended range with respect to the desired operating point differs from the current valve travel. By means of these measures, the fuel saving operating range of the internal combustion engine is enlarged.