Shielded Ion Sensor for Diesel Engine Cold Start Control
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Solution Overview
Problem
Existing ion current detection methods in diesel engines are prone to inaccuracies due to carbon buildup and electrode damage, leading to incorrect ignition and flame detection, especially during cold starts, which affects the reliability of emission monitoring and control.
Innovation Solution
A method and apparatus using a shielded spark plug type of sensor or an ion sensor integrated into the fuel injector to detect ionization current, which provides reliable feedback for engine control, including exhaust gas recirculation and diesel injection timing, while preventing misfires and reducing cold start emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional ion current detection methods are used in diesel engines, then the system structure is simple, but the detection accuracy deteriorates due to carbon buildup and electrode damage
Solution Approach 1:
The patent introduces a shielded sensor design where a conductive shield acts as an intermediary between the ionization measurement zone and the combustion chamber environment. The shield is biased at a specific potential to repel carbon particles and prevent them from reaching the sensing electrode, thereby maintaining detection accuracy without requiring additional heating systems.
Solution Approach 2:
The patent applies preliminary protective action by pre-biasing the conductive shield to a negative potential before carbon buildup can occur. This preliminary anti-action prevents carbon particles from adhering to the electrode surface in the first place, eliminating the need for post-problem corrections such as heating systems or sensor replacement.
2Reliability
If additional heating systems are used during cold starts, then the reliability of combustion improves, but the device complexity and energy consumption increase
Solution Approach 1:
The patent enables the ionization detection system to serve dual purposes: it not only detects combustion conditions but also actively prevents carbon buildup through its biased shield. This self-service capability eliminates the need for separate heating systems, reducing device complexity while maintaining cold start reliability.
Solution Approach 2:
The conductive shield is designed to perform multiple functions simultaneously: it shields the electrode from carbon particles, maintains the electric field for ionization detection, and prevents carbon adhesion through its biased potential. This multi-functionality replaces what would otherwise require separate heating and detection systems.
3Measurement precision
If the ion sensor is exposed to the combustion chamber environment, then the detection capability is maintained, but carbon buildup on the electrode causes measurement errors
Solution Approach 1:
The conductive shield serves as a protective intermediary between the combustion chamber environment and the sensing electrode. By biasing the shield to a negative potential, carbon particles are repelled and prevented from reaching the electrode, while the shield itself does not interfere with the ionization measurement field.
Solution Approach 2:
The patent employs a thin conductive shield structure that acts as a protective barrier. This thin film approach allows the shield to effectively block carbon particles from reaching the electrode while maintaining transparency to the ionization field, ensuring measurement accuracy is preserved.
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 enables accurate detection and control of ionization signals, improving engine performance by reducing NOx emissions, preventing misfires, and eliminating the need for additional heating systems during cold starts, thus enhancing the reliability of diesel engine operation.
Implementation Method 1
measuring an ionization signal in the combustion chamber of the cylinder
Implementation Method 2
cold start combustion is started with a plasma discharge ignition system
Data Source
AI summary
An apparatus and method to detect combustion conditions using ion signals for use in a feedback control of a reciprocation engine is presented. The ion signals are used as a feedback signal to control EGR and diesel injection timing. The apparatus is an ignition system with a spark plug type of sensor. The ignition system is used to provide a cold start mechanism for diesel engines and start of combustion for spark ignition engines. The ignition is combined with ion sensing feedback that can control the engine.