Engine Control Device for Cylinder-Specific Combustion Failure Detection
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Solution Overview
Problem
Internal-combustion engines face challenges in accurately determining the combustion state of an air-fuel mixture during transitions between steady and transient operation states, leading to potential misclassification of combustion stability and subsequent unnecessary adjustments that deteriorate fuel efficiency and exhaust purification performance.
Innovation Solution
The solution involves an output fluctuation value calculation unit and a state determination unit that differentiate between steady and transient operation states by analyzing the difference or ratio of output fluctuation values between cylinders, allowing for accurate combustion failure determination only in the steady operation state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If torque fluctuation amount is calculated based on combustion pressure change in each cycle to detect combustion instability, then combustion state can be monitored, but in transient operation state the calculation includes both combustion fluctuation and engine torque fluctuation leading to erroneous determination
Solution Approach 1:
The patent segments the torque fluctuation analysis by separating combustion-related fluctuations from engine torque-related fluctuations. This is achieved by calculating torque fluctuation amounts for individual cylinders and comparing them, allowing the system to identify combustion instability specifically in one cylinder rather than mistaking overall engine torque changes during transient operations for combustion problems.
Solution Approach 2:
The patent applies local quality by focusing on cylinder-specific torque fluctuation characteristics rather than overall engine torque. By analyzing torque fluctuation amounts for each cylinder individually and comparing relative differences, the system can detect local combustion instability in specific cylinders while ignoring global engine torque changes that occur during transient operations.
2Stability of the object's composition
If control parameters are adjusted based on calculated torque fluctuation amount to stabilize combustion, then combustion stability improves, but unnecessary adjustments during transient operation deteriorate fuel efficiency and exhaust purification performance
Solution Approach 1:
The patent introduces dynamic judgment criteria that adapt to different engine operating states. The control system dynamically determines whether torque fluctuation reflects combustion instability or transient operation by comparing torque fluctuation characteristics across cylinders and evaluating whether fluctuations exceed predetermined thresholds specific to each operating condition, thereby avoiding unnecessary control adjustments during transient states.
Solution Approach 2:
The patent employs feedback mechanisms where the control device continuously monitors torque fluctuation amounts and compares them against dynamically determined thresholds. The system only executes combustion stabilization control when the feedback indicates genuine combustion instability (i.e., when cylinder-specific torque fluctuation exceeds thresholds during steady-state operation), preventing wasteful adjustments during transient operations.
3Speed
If combustion failure determination is performed using torque fluctuation data during operation state transitions, then real-time control is maintained, but determination accuracy decreases due to mixed transient torque fluctuations
Solution Approach 1:
The patent prepares predetermined thresholds and judgment criteria in advance for different engine operating states. Before performing combustion failure determination, the system evaluates current operating conditions and selects appropriate thresholds, ensuring that determination is only performed when conditions are suitable (i.e., during steady-state operation), thus maintaining both real-time responsiveness and determination accuracy.
Data Source
AI summary
Provided is a novel internal-combustion engine control device that can accurately determine a combustion state of an air-fuel mixture in a combustion chamber even in a case where operation is switched between a steady operation state and a transient operation state. For this purpose, the internal-combustion engine control device includes a physical quantity detection unit that detects a physical quantity that fluctuates output of the internal-combustion engine, an output fluctuation value calculation unit that calculates an output fluctuation value for each cylinder based on a detection result of the physical quantity detection unit, and a state determination unit that determines a transient operation state or a steady operation state based on a difference or a ratio between a first output fluctuation value of a predetermined first cylinder and a second output fluctuation value of a predetermined second cylinder calculated by the output fluctuation value calculation unit. Since combustion failure determination is performed in a section determined as the steady state, it is possible to accurately determine a combustion failure state of an air-fuel mixture of a cylinder even in a case where operation is switched between the steady operation state and the transient operation state.