Turbocharger Wastegate Control Law for Pressure Stability
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Solution Overview
Problem
Internal combustion engines with turbochargers face challenges in maintaining stable supercharging pressure due to high structure dispersion, thermal drift, and hysteresis in pneumatic actuators, leading to overshoots and oscillations, especially when the wastegate is around the operating threshold.
Innovation Solution
A method that determines a control law to correct the reduced mass flow rate of the compressor by considering the enthalpy of the gas mixture flowing through the turbine and fresh air passing directly from the intake manifold to the exhaust manifold, using a combination of open-loop and closed-loop contribution factors, and adaptive filtering to stabilize the wastegate operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pneumatic actuator with contrast spring is used to control the wastegate, then the wastegate can be operated to regulate supercharging pressure, but high structure dispersion, thermal drift, and hysteresis cause overshoots and oscillations in pressure control
Solution Approach 1:
The patent implements a closed-loop feedback control system where the actual supercharging pressure is continuously measured and compared with the target pressure. The control unit adjusts the wastegate position based on the pressure error signal, creating a feedback mechanism that compensates for the hysteresis and drift characteristics of the pneumatic actuator, thereby stabilizing the supercharging pressure and eliminating overshoots and oscillations.
2Manufacturing precision
If the wastegate is controlled around the operating threshold to maintain target supercharging pressure, then pressure regulation is achieved, but the system becomes highly sensitive to actuator drift and hysteresis causing oscillations
Solution Approach 1:
The control system performs self-adjustment by continuously monitoring the actual supercharging pressure and automatically compensating for actuator characteristics. The control unit calculates the required wastegate position based on real-time pressure feedback, enabling the system to self-correct for drift and hysteresis effects without external intervention, thus maintaining precise pressure regulation while improving operational robustness.
3Productivity
If direct passage of air from intake manifold to exhaust manifold is allowed, then engine performance is improved, but the reduced mass flow rate of the compressor must be corrected to maintain accurate control
Solution Approach 1:
The patent introduces a correction factor that modifies the reduced mass flow rate calculation based on the enthalpy of the gas mixture in the exhaust manifold. When direct air passage occurs, the composition and enthalpy of the exhaust gases change; the control unit detects these changes and adjusts the mass flow rate parameter accordingly, maintaining measurement accuracy despite the altered exhaust conditions and enabling continued precise control of the turbocharger system.
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 method stabilizes the supercharging pressure, reduces overshoots and oscillations, and ensures robust, prompt, and oscillation-free control of the wastegate in all operating conditions, including those with significant air passage from the intake to the exhaust.
Implementation Method 1
exploiting the enthalpy of exhaust gases to compress the air aspirated by the engine
Implementation Method 2
A contrast spring is arranged in the first chamber such that it is compressed between a wall of the shell and the flexible diaphragm
Implementation Method 3
when the pressure difference between the two chambers is higher than the operating threshold, the contrast spring starts to compress under the thrust of the flexible diaphragm, which thus deforms and causes a displacement of the rod
Data Source
AI summary
A method for correcting the reduced mass flow rate of a compressor in an internal combustion engine turbocharged with a turbocharger provided with a turbine and with a compressor; the internal combustion engine including an intake manifold and an exhaust manifold, and being set up to allow the passage of air from the intake manifold to the exhaust manifold; the method including determining, in a design stage, a control law that provides a target opening of a control actuator of the wastegate as a function of an actual supercharging pressure and of a reduced mass flow rate of the compressor; and correcting the reduced mass flow rate of the compressor as a function of the enthalpy of a gas mixture flowing through the turbine of the turbocharger.