Diesel Engine Air System Decoupling Control via Transfer Function
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Solution Overview
Problem
Existing control strategies for diesel engine air systems, particularly those incorporating exhaust gas recirculation (EGR) and turbocharge systems, face challenges in achieving precise control due to strong coupling and non-linear correlations, leading to unsatisfactory steady-state and transient performance, with limitations in EGR flow estimation and calibration complexity.
Innovation Solution
A control apparatus and method that computes a decoupling transfer function to generate independent driving signals for the EGR and turbocharge systems, allowing for decoupling and independent calibration of these systems, thereby improving control efficacy and simplifying calibration processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If independent control strategy with PID control is used for EGR and turbocharge systems, then the control structure is simple and steady-state control effect is good, but the coupling characteristic causes unsatisfactory dynamic process control effect and smoking phenomenon appears during acceleration
Solution Approach 1:
The patent segments the coupled EGR and turbocharge control system into two independent control loops by introducing a decoupling mechanism. The EGR valve control and turbocharger control are separated through feedforward compensation, allowing each subsystem to be controlled independently while accounting for their mutual influences, thus simplifying the control structure while improving dynamic response
Solution Approach 2:
The patent applies preliminary action by implementing feedforward control that anticipates the coupling effects between EGR and turbocharge systems. The controller pre-calculates and compensates for the influence of EGR valve opening on turbocharger performance and vice versa, preventing smoking phenomenon during acceleration before it occurs
2Adaptability or versatility
If local linearization and optimal controller design methods are used, then a non-linear control strategy covering entire operation scope is obtained, but the control strategy complexity increases significantly
Solution Approach 1:
The patent changes the control parameters from complex non-linear state variables to simpler, more directly measurable parameters. By focusing control on key parameters like EGR valve opening and turbocharger actuator position with feedforward compensation, the system achieves good adaptability across operation ranges without requiring complex non-linear control algorithms
3Ease of manufacture
If EGR flow estimation is used instead of direct measurement, then the control system can be implemented with available sensors, but the estimation accuracy is insufficient and requires enormous testing work
Solution Approach 1:
The patent implements feedback control using readily available sensors to measure actual EGR flow and turbocharger performance. The measured values are fed back to the controller, which adjusts the EGR valve and turbocharger actuator positions in real-time to maintain desired performance, eliminating the need for complex estimation algorithms while improving measurement accuracy
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
The solution effectively controls the diesel engine air system in a steady state, ensuring independent operation and calibration of the EGR and turbocharge systems, enhancing the air control system's functionality and simplifying the calibration process.
Implementation Method 1
The turbocharing system is essentially an air compression system, in which air intake volume increases in the diesel engine cylinders through compressing air. It is driven by the impact force from the exhaust gas emitted from the engine.
Implementation Method 2
the flow of the exhaust gas input in an EGR cooler is controlled by an EGR valve
Data Source
AI summary
A control device and method for the air system of a diesel engine is disclosed. The feature of the diesel engine is characterized by transfer function. During the control process, a decoupling transfer function is computed according to the transfer function and the steady working parameters of the diesel engine. By the decoupling transfer function acting on the processed state parameters of the air system, driving signals for controlling the exhaust gas recirculation system and the turbocharge system can be individually generated from one another, in order to realize decoupling of them.