Engine Combustion Control Using Plant Models for Cycle Stability
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Solution Overview
Problem
Conventional internal combustion engine control systems fail to account for the regular combustion variations that occur across multiple cycles due to the influence of previous cycles, leading to inefficiencies and variations in combustion performance.
Innovation Solution
An engine control system that utilizes a plant model to estimate combustion variations across cycles and adjusts control signals for devices like injectors and spark plugs based on estimated state quantities, reducing regular combustion variations by correcting control variables before each cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the conventional control apparatus measures state quantities of the cylinder for each cycle and corrects control variables, then the combustion control is adjusted based on current cycle conditions, but the long-term combustion variations across multiple cycles cannot be detected or reduced
Solution Approach 1:
The control apparatus performs preliminary estimation of state quantities (temperature, air amount, burned gas amount, fuel amount) before combustion occurs in each cylinder using a plant model. This allows the system to predict and prepare for combustion variations in advance, rather than merely reacting to measured values after combustion has occurred. The estimated values are used to correct control signals before they are sent to the combustion control device.
Solution Approach 2:
The system implements a feedback mechanism where the plant model continuously estimates state quantities based on previous combustion results and system conditions. These estimated values feed back into the control signal correction process, creating a closed-loop system that adapts to long-term combustion variations. The feedback enables the system to detect patterns across multiple cycles and adjust control variables accordingly.
2Reliability
If the controller corrects control signals based on estimated state quantities from a plant model, then regular combustion variations across cycles are reduced, but the computational complexity and model requirements increase
Solution Approach 1:
The plant model serves as an intermediary between the measured combustion results and the control signal correction. Rather than directly processing raw measurement data, the system uses the plant model to estimate intermediate state quantities (temperature, air amount, burned gas amount, fuel amount) that bridge the gap between observations and control actions. This intermediary layer simplifies the overall control logic while improving accuracy.
Solution Approach 2:
The system changes the parameters used for control by estimating multiple state quantities (temperature, air amount, burned gas amount, fuel amount) rather than relying on a single measured parameter. This multi-parameter approach allows for more nuanced control signal correction and better handling of combustion variations, while the plant model efficiently manages the complexity of processing these multiple parameters.
Data Source
AI summary
To reduce regular combustion variations across combustion cycles, an engine control apparatus includes: an engine that has cylinders inside of which gas exchange is performed by opening and closing an intake valve and an exhaust valve for each cylinder, and that is operated by causing a plurality of the cylinders to sequentially execute combustion cycles; a combustion control device that is attached to the engine, and controls combustion in each of the plurality of cylinders; and a controller that controls the operation of the engine by outputting a control signal to the device, wherein the controller, before combustion in each of the plurality of cylinders, estimates state quantities of the cylinder based on a plant model of the engine which indicates regular combustion variations across the combustion cycles, and outputs to the combustion control device the control signal, which has been corrected based on the estimated state quantities.