Variable Compression Ratio Engine Wastegate Control
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Solution Overview
Problem
In internal combustion engines with a variable compression ratio mechanism, controlling the supercharging pressure of a turbocharger is challenging when the mechanical compression ratio changes, especially during engine transitions or when knocking occurs, as it affects the wastegate valve's target opening degree.
Innovation Solution
The engine adjusts the wastegate valve's opening degree in real-time based on the current engine operating state and mechanical compression ratio to maintain desired supercharging pressure, even when the engine state is steady or transitioning, by correcting the target opening degree to account for changes in mechanical compression ratio and knocking occurrences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the mechanical compression ratio is lowered to suppress knocking, then knocking is suppressed, but the supercharging pressure control becomes impossible
Solution Approach 1:
The system dynamically changes the target opening degree of the wastegate valve based on the mechanical compression ratio. When the mechanical compression ratio is lowered to suppress knocking, the control unit simultaneously adjusts the target opening degree of the wastegate valve to maintain appropriate supercharging pressure, thus resolving the contradiction between knocking suppression and supercharging pressure control
Solution Approach 2:
The control unit continuously monitors the mechanical compression ratio and adjusts the wastegate valve's target opening degree accordingly. This feedback mechanism ensures that when compression ratio changes occur (whether for knocking suppression or thermal efficiency improvement), the supercharging pressure remains properly controlled through real-time adjustment of the wastegate valve position
2Loss of energy
If the mechanical compression ratio is changed during engine transition, then thermal efficiency is improved, but the supercharging pressure control becomes unstable
Solution Approach 1:
The control unit predicts the required wastegate valve opening degree based on the current engine operating state and the intended mechanical compression ratio change. By preliminarily adjusting the target opening degree in anticipation of compression ratio changes during engine transitions, the system maintains stable supercharging pressure control while allowing thermal efficiency improvement through compression ratio variation
Solution Approach 2:
The system dynamically adjusts the target opening degree of the wastegate valve in response to mechanical compression ratio changes during engine transitions. This parameter change approach allows the system to exploit compression ratio variations for thermal efficiency improvement while simultaneously maintaining supercharging pressure stability through coordinated wastegate valve control
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach ensures consistent supercharging pressure control, optimizing thermal efficiency and preventing excessive supercharging pressure, thereby improving engine performance and reducing knocking incidents.
Implementation Method 1
a compressor of a turbocharger is arranged in an engine intake system, a turbine of the turbocharger is arranged in an engine exhaust system
Implementation Method 2
a turbine of the turbocharger is arranged in an engine exhaust system
Implementation Method 3
By controlling the opening degree of the wastegate valve, the turbine speed made to change to control the supercharging pressure of the compressor to the desired supercharging pressure
Data Source
AI summary
This internal combustion engine provided with a variable compression ratio mechanism is equipped with a turbocharger, the opening degree of a wastegate valve is controlled to a target opening degree for each engine operating state, and when the mechanical compression ratio is changed, the target opening degree of the wastegate valve for the current engine operating state is revised.