Auxiliary Chamber Ignition Control for Abnormal Combustion Prevention
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Solution Overview
Problem
Engines with auxiliary combustion chambers and ignition plugs face challenges in controlling operation without increasing manufacturing costs, particularly due to the risk of abnormal combustion from high temperatures, which existing solutions attempt to mitigate by adding sensors.
Innovation Solution
An internal combustion engine control device that estimates the temperature of the auxiliary combustion chamber and adjusts the ignition timing to prevent abnormal combustion without requiring additional sensors, using a system that delays ignition timing based on temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If an auxiliary combustion chamber is added to increase engine output and improve fuel consumption, then engine power and efficiency are improved, but the temperature of the auxiliary chamber increases causing abnormal combustion (pre-ignition) risk
Solution Approach 1:
The control device performs preliminary detection of abnormal combustion conditions by monitoring discharge voltage and pressure, and takes preventive action by adjusting ignition timing before pre-ignition occurs. The ECU retards ignition timing when abnormal combustion is detected, preventing the harmful effect from manifesting.
Solution Approach 2:
The system continuously monitors the auxiliary chamber's discharge voltage and pressure, compares these parameters against threshold values, and adjusts ignition timing based on the feedback. This closed-loop control allows the system to adapt to temperature changes and prevent abnormal combustion while maintaining engine output.
2Measurement precision
If pressure sensors and discharge voltage sensors are added to detect abnormal combustion, then detection precision is improved, but manufacturing cost increases
Solution Approach 1:
The ignition plug itself serves as the detection sensor by utilizing its existing discharge voltage output to monitor abnormal combustion conditions. The system leverages the plug's inherent electrical characteristics rather than requiring separate detection devices, thereby avoiding additional manufacturing costs while achieving the needed measurement precision.
Solution Approach 2:
The discharge voltage detection mechanism serves dual purposes: it monitors combustion health for abnormal combustion detection and simultaneously provides information for optimizing ignition timing control. This multi-functionality eliminates the need for dedicated temperature or pressure sensors in the ignition plug.
3Reliability
If ignition timing is delayed to prevent pre-ignition, then abnormal combustion is prevented, but engine power output decreases
Solution Approach 1:
The ignition timing is made dynamic rather than fixed, allowing the ECU to adjust timing based on real-time combustion conditions. During normal operation, optimal timing maintains power output, but when abnormal combustion is detected, timing is dynamically retarded to prevent pre-ignition. This dynamic adjustment resolves the contradiction by adapting timing to actual combustion needs.
Solution Approach 2:
The system changes the ignition timing parameter in response to detected combustion abnormalities. By monitoring discharge voltage and pressure parameters, the ECU adjusts timing to prevent pre-ignition while minimizing power loss. The parameter change is conditional and reversible, maintaining power output when conditions are normal.
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 approach allows for controlled engine operation with an auxiliary chamber ignition plug without new sensors, stabilizing combustion across varying temperatures and preventing misfires and overheating.
Implementation Method 1
a primary coil that causes a primary current to flow, a secondary coil in which a change in magnetic flux generated in the primary coil is induced
Implementation Method 2
a discharge spark is generated in an ignition plug by a high voltage generated in a secondary coil, and an air-fuel mixture is ignited
Implementation Method 3
an air-fuel mixture in which a fuel injected by a fuel injection device and air taken in from an intake system are mixed is combusted in a main combustion chamber
Data Source
AI summary
In an engine including an auxiliary chamber having an ignition plug therein, an amount of heat generated in the auxiliary chamber tends to be large, and thus it is necessary to suppress abnormal combustion. However, when a sensor is added to the ignition plug, a manufacturing cost of the ignition plug tends to increase. An ECU 2 includes an auxiliary chamber temperature estimation unit 21 that estimates a temperature of the auxiliary chamber 42, and an ignition control unit 22 that delays an ignition timing at a first decrease degree defined in accordance with a change amount of the ignition timing with respect to the temperature of the auxiliary combustion chamber as the temperature of the auxiliary chamber 42 increases in a case where the estimated temperature of the auxiliary chamber 42 is included in a middle temperature region equal to or lower than a first set temperature.