Turbocharger Compressor Control via Gas Flow Change Rate
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Solution Overview
Problem
Internal combustion engines with turbochargers face inefficiencies due to mechanical inertia and delayed responses in gas flow changes, leading to undesirable surging and reduced compressor efficiency during unsteady operations.
Innovation Solution
A method to dynamically regulate the compressor based on the change in gas flow quantity, using an estimated gas flow quantity that accounts for turbocharger inertias, allowing proactive adjustment of pressure ratio and rotational speed to prevent surging and enhance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the compressor is controlled based on a steady surge limit line, then the risk of surging is reduced in steady operation, but the compressor efficiency deteriorates in unsteady operation due to mechanical inertia and delayed response
Solution Approach 1:
The control system performs preliminary action by proactively adjusting the compressor pressure ratio and rotational speed based on the change quantity of gas flow before the actual gas flow change occurs. This anticipatory control compensates for mechanical inertia and dead time, allowing the compressor to respond to gas flow changes without delay, thus preventing surge while maintaining efficiency in unsteady operation
Solution Approach 2:
The invention transitions from static surge limit line control to dynamic control by continuously adjusting the surge limit based on the change quantity of gas flow. The control system dynamically modifies the pressure ratio and rotational speed setpoints according to the rate of gas flow change, enabling adaptive response to both steady and unsteady operating conditions, thereby resolving the contradiction between surge prevention and efficiency
2Reliability
If the surge limit line is restrictively preset to account for inertia during gas flow diminishment, then surging is excluded, but the compressor efficiency deteriorates in steady operation due to larger safety intervals
Solution Approach 1:
The control system dynamically adjusts the surge limit based on the change quantity of gas flow. During steady operation with minimal gas flow change, the surge limit is set closer to the actual surge boundary, maximizing efficiency. During unsteady operation with significant gas flow change, the surge limit is adjusted proactively to prevent surge. This dynamic adaptation eliminates the need for conservative fixed safety margins
3Productivity
If the compressor responds immediately to gas flow changes, then compressor efficiency is maximized, but mechanical inertia and dead time cause delayed response leading to excessive pressure ratio and surging
Solution Approach 1:
The control system performs preliminary action by calculating the change quantity of gas flow and proactively adjusting the compressor pressure ratio and rotational speed before the actual gas flow change occurs. This anticipatory control compensates for mechanical inertia and dead time, allowing the compressor to respond effectively to gas flow changes without delay, thus preventing surge while maintaining efficiency
Solution Approach 2:
The control system uses feedback from gas flow measurements to continuously adjust the compressor operating point. By monitoring the change quantity of gas flow and comparing it with the desired response, the system dynamically modifies the pressure ratio and rotational speed setpoints, creating a closed-loop control that overcomes the limitations of mechanical inertia and dead time
Data Source
AI summary
The present disclosure relates to a method for operating an internal combustion engine for a motor vehicle, in particular a passenger car having a turbocharger with a compressor and a turbine. The method includes determining a change quantity of a gas flow quantity of a gas flow through the internal combustion engine and regulating the compressor based on this change quantity.