Oxygen Sensor LSPI Detection in Turbocharged Engines
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Solution Overview
Problem
Internal combustion engines face challenges in detecting and inhibiting low-speed pre-ignition (LSPI) events, which occur randomly and are difficult to eliminate, leading to engine damage, high emissions, and lost power, especially in turbocharged gasoline engines operating at low speeds and medium-to-high loads.
Innovation Solution
A method using an oxygen sensor to detect LSPI events by monitoring exhaust gas and adjusting engine operating parameters, such as fuel injection and ignition timing, to prevent subsequent pre-ignition events, thereby inhibiting LSPI before damage occurs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If traditional knock sensors are used to detect abnormal combustion, then detection capability is provided, but the sensors are difficult to replace and require close proximity to the cylinder
Solution Approach 1:
The patent uses exhaust gas as an intermediary medium to carry information about combustion events from the cylinder to the sensor. Instead of placing the sensor directly in the combustion chamber or close to the cylinder, the sensor is positioned in the exhaust system where it detects chemical signatures (HC, CO, O2, NOx) that serve as mediators of combustion state, thereby eliminating the need for close sensor-cylinder proximity while maintaining detection capability
Solution Approach 2:
The patent replaces the mechanical/vibration-based knock sensor system with a chemical sensing system. Instead of detecting mechanical vibrations or pressures from abnormal combustion, the system uses chemical sensors to detect exhaust gas composition changes, substituting a complex mechanical detection and replacement system with a simpler chemical analysis approach that allows for easier sensor installation and replacement
2Difficulty of detecting and measuring
If multiple knock sensors are used to cover all cylinders, then detection coverage is improved, but system complexity and cost increase
Solution Approach 1:
The patent makes the exhaust sensor system universal by using a single sensor type that can detect multiple combustion parameters (HC, CO, O2, NOx) across all cylinders through the shared exhaust system. Instead of requiring separate dedicated sensors for each cylinder, one sensor performs multiple detection functions by analyzing the chemical composition of exhaust gas from all cylinders, thereby reducing system complexity while maintaining comprehensive detection coverage
Solution Approach 2:
The patent merges the detection functions for multiple cylinders into a single sensor system. Rather than having separate sensors for each cylinder, the system combines all cylinder exhaust flows into a single detection point where the sensor analyzes the composite exhaust gas, merging multiple detection tasks into one unified measurement process that reduces hardware complexity
3Difficulty of detecting and measuring
If pre-ignition events are allowed to occur, then combustion can be detected, but engine damage occurs and power is lost
Solution Approach 1:
The patent applies preliminary action by detecting pre-ignition events before they cause engine damage. The sensor system identifies abnormal combustion chemical signatures in the exhaust stream during or immediately after the combustion event, allowing the control system to take corrective action (such as adjusting ignition timing or fuel injection) before the next combustion event, thereby preventing cumulative damage while maintaining detection capability
Solution Approach 2:
The patent implements feedback by continuously monitoring exhaust gas composition and using this information to adjust engine operating parameters. The sensor provides real-time feedback on combustion quality, and the control system responds by modifying ignition timing, fuel injection amounts, or other parameters to prevent pre-ignition events from causing damage, creating a closed-loop system that protects engine reliability while maintaining combustion detection
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 method effectively detects LSPI events on a cycle-by-cycle basis and inhibits their occurrence by adjusting engine parameters, reducing the risk of engine damage and emissions, and maintaining optimal engine performance.
Implementation Method 1
monitoring the exhaust gas from the cylinder with an oxygen sensor while the internal combustion engine undergoes a pre-ignition combustion event
Data Source
AI summary
The disclosure provides a method of detecting and inhibiting an abnormal combustion event in an internal combustion engine, comprising operating the internal combustion engine to produce exhaust gas from the cylinder at a break mean effective pressure greater than or equal to 10 bars at a speed less than or equal to 2,000 revolutions per minute; monitoring the exhaust gas from the cylinder with an oxygen sensor while the internal combustion engine undergoes a pre-ignition combustion event; obtaining an output from the oxygen sensor, the output from the oxygen sensor providing an indicator of the pre-ignition combustion event; and adjusting at least one operating parameter of the internal combustion engine in response to the output of the oxygen sensor, wherein the at least one operating parameter is adjusted to inhibit an occurrence of a subsequent pre-ignition combustion event.