Electrically Isolated Fuel Injector Ionization Sensing
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Solution Overview
Problem
Current systems for detecting ionization current in diesel engines are limited by high costs and durability issues of pressure transducers, and typical ionization conditioning circuitry is degraded by thermal and magnetic conditions, leading to a low signal-to-noise ratio and soot deposits.
Innovation Solution
An electrically isolated fuel injector system with an ionization detection circuit, including a power source and signal conditioning unit, is used to sense ionization current within the combustion chamber, utilizing an electrically insulated fuel injector and a glow plug with an integrated ion sensor to improve signal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressure transducers are used to detect cylinder gas pressure, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses ionization current as an intermediary parameter to indirectly measure combustion conditions. Instead of directly measuring cylinder pressure with complex transducers, the system detects ionization current generated during combustion, which serves as a mediator that correlates with combustion quality and pressure conditions without requiring direct pressure sensing hardware.
Solution Approach 2:
The patent replaces the mechanical pressure transducer system with an electrical ionization detection system. By substituting the mechanical sensing approach (pressure transducers) with an electrical field-based approach (ionization current measurement), the system achieves comparable measurement capability with reduced complexity and cost.
2Measurement precision
If ionization conditioning circuitry is positioned close to the glow plug for signal detection, then signal strength is improved, but thermal and magnetic interference increases
Solution Approach 1:
The patent introduces an intermediary coupling mechanism (such as capacitive coupling or inductive coupling) between the ionization detection circuitry and the combustion chamber environment. This intermediary allows the weak ionization signal to be transmitted to the conditioning circuitry without requiring direct physical proximity, thereby maintaining signal strength while avoiding thermal and magnetic interference from the glow plug and combustion process.
3Adaptability or versatility
If the fuel injector is electrically isolated from the engine body, then ionization detection capability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent designs the fuel injector to serve multiple functions: its primary fuel injection function and its secondary function as an ionization sensor. By making the fuel injector body itself electrically conductive and isolated from the engine block, it can detect ionization current without requiring separate sensing components. This multi-functionality approach adds minimal manufacturing complexity while enabling advanced combustion monitoring capabilities.
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 system effectively detects ionization current, providing precise feedback for controlling combustion processes, reducing emissions, and enhancing engine performance without requiring significant engine modifications.
Implementation Method 1
ionization sensors are operable to detect the combustion process based on the theory that positive and negative ions are generated during the combustion process
Data Source
AI summary
A multi-sensing fuel injection system for internal combustion engines. The system includes a fuel injector for injecting fuel into the internal combustion chamber. The fuel injector is electrically insulated from an engine body of the internal combustion engine by way of a first electrically insulated member. A second electrically insulated member is provided for fixedly disposing the fuel injector within the combustion chamber. The electrical insulation of the fuel injector, in conjunction with the integration of an ion sensing circuit including a resistor and a power source for supplying voltage to the fuel injector, allows for a full measurement of the ionization current.