Divided-Chamber Engine Knock Control via Sub-Chamber Fuel Reduction
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Solution Overview
Problem
Divided-combustion-chamber engines face challenges in fuel injection timing and ignition control, leading to difficulties in stabilizing combustion due to knocking or combustion failure, particularly when the air-fuel ratio is lean.
Innovation Solution
A control device with main-chamber and sub-chamber fuel injection means, coupled with an ECU that estimates knocking intensity and frequency, adjusts fuel amounts, and retards ignition timing to stabilize combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional engine control device is used, then the control logic is simple and device complexity is low, but measurement precision and reliability deteriorate when multiple sensors fail or output abnormal values
Solution Approach 1:
The control device performs preliminary determination of whether a sensor is abnormal by comparing sensor output values with predetermined threshold values before using the sensor data for control decisions. This preliminary action prevents propagation of erroneous data from failed sensors, improving measurement precision without requiring complex real-time analysis during normal operation.
Solution Approach 2:
The control device establishes a feedback mechanism where sensor outputs are continuously monitored and compared against threshold values. When abnormal values are detected, the system provides feedback to switch between sensor inputs or adjust control strategies, ensuring reliable operation even when multiple sensors fail. This feedback loop maintains determination accuracy while keeping the control logic structured and manageable.
2Reliability
If multiple sensors are used to improve reliability, then reliability deteriorates when sensor failures occur and abnormal values are output
Solution Approach 1:
When sensor failures are detected through threshold comparison, the control device extracts and removes the abnormal sensor data from the control calculation. By taking out the unreliable sensor inputs, the system maintains control reliability using only valid sensor data, preventing the propagation of measurement errors while preserving overall system reliability.
Solution Approach 2:
The control device dynamically changes operational parameters by switching between different sensor inputs based on their validity. When a sensor outputs abnormal values, the system changes the active sensor parameter to an alternative valid sensor, thereby maintaining measurement precision and control reliability even in the presence of sensor failures.
3Object-affected harmful factors
If sensor output values are not verified, then device complexity is low, but harmful factors increase due to incorrect control decisions
Solution Approach 1:
The control device performs preliminary verification of sensor output values by comparing them against predetermined threshold values before using the data for control decisions. This preliminary check prevents incorrect control decisions caused by abnormal sensor readings while maintaining a relatively simple verification process that does not require complex real-time analysis.
Solution Approach 2:
The control device introduces threshold values as an intermediary reference for verifying sensor outputs. This intermediary mechanism provides a simple yet effective way to detect abnormal sensor values and prevent harmful control decisions without requiring complex verification algorithms, thus reducing the complexity of the verification process while eliminating harmful factors.
Data Source
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Figure 2
Figure 3~4B
AI summary
A control device for controlling an engine includes main-chamber injecting means (1,3) that supplies a main chamber (8) with fuel; sub-chamber injecting means (2) that supplies a sub chamber (5) with fuel after the main chamber injecting means (1,3) supplies the fuel; estimating means (21) that estimates a degree of knocking serving as indices of an intensity of the knocking and an occurrence frequency of the knocking; and fuel controlling means (22) that carries out, when the degree (N) of the knocking is a first predetermined value (N1) or more, fuel control that reduces a sub-chamber fuel amount representing an amount of fuel supplied by the sub-chamber injecting means (2). By reducing the sub-chamber fuel amount in this manner, the occurrence of knocking can be suppressed, so that the combustion state of a divided-combustion-chamber engine can be enhanced.