Spark Ignition Engine S-V Ratio Correction for Hydrogen Sensor Deviation
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Solution Overview
Problem
In spark ignition type internal combustion engines with high mechanical compression ratios, the increased surface-volume ratio leads to higher hydrogen concentrations in exhaust gases, causing oxygen and air-fuel ratio sensors to deviate, resulting in inaccurate detection and control of air-fuel ratios, which affects combustion efficiency and exhaust emissions.
Innovation Solution
A control system that adjusts the output values of detection devices and operational parameters based on the surface-volume ratio and other factors, such as intake valve timing and EGR valve opening, to correct for the increased hydrogen concentration and maintain suitable air-fuel ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the mechanical compression ratio is raised to increase expansion ratio and heat efficiency, then the S/V ratio increases and hydrogen concentration in exhaust gas increases, but this causes oxygen sensors and air-fuel ratio sensors to deviate and cannot accurately detect exhaust gas composition
Solution Approach 1:
The patent applies parameter changes by correcting the output values of detection devices based on the S/V ratio. The ECU calculates the S/V ratio from combustion chamber volume and piston displacement volume, then uses this parameter to correct sensor outputs. When S/V ratio exceeds a threshold (indicating high hydrogen concentration), the system adjusts the detected oxygen concentration and air-fuel ratio values to compensate for hydrogen interference, thereby maintaining measurement accuracy despite the fundamental parameter change of high compression ratio operation.
2Productivity
If the S/V ratio becomes extremely large in high compression ratio engines, then hydrogen concentration in exhaust gas becomes large, but this causes the output value of oxygen sensor or air-fuel ratio sensor to greatly deviate to the rich side
Solution Approach 1:
The patent replaces direct physical measurement with a calculated correction system. Instead of relying solely on physical sensor measurements that are affected by hydrogen, the system substitutes a mathematical correction model that calculates the expected hydrogen concentration based on S/V ratio and subtracts its effect from the sensor readings. This substitution of direct measurement with calculated compensation maintains information accuracy despite the presence of high hydrogen concentrations.
3Loss of energy
If variable compression ratio mechanism is used to raise mechanical compression ratio, then expansion ratio increases and heat efficiency improves, but the quench region becomes relatively larger and HC conversion to hydrogen increases
Solution Approach 1:
The patent converts the harmful effect of increased hydrogen concentration into a beneficial correction factor. Rather than viewing high hydrogen levels as merely a problem to be eliminated, the system uses the known relationship between S/V ratio and hydrogen concentration to create a predictive correction model. The hydrogen that would normally cause measurement errors is instead used as the basis for a systematic correction approach, turning the adverse effect into a controllable parameter that improves overall system accuracy.
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 system ensures accurate control of air-fuel ratios, improving combustion efficiency and reducing exhaust emissions by compensating for the effects of increased hydrogen concentrations in the exhaust gases.
Implementation Method 1
an oxygen sensor or air-fuel ratio sensor which detects an oxygen concentration in the exhaust gas or air-fuel ratio
Implementation Method 2
the HC in the air-fuel mixture which was included in this quench region is exposed to a high temperature along with combustion of the air-fuel mixture, so part is converted to hydrogen (H2)
Data Source
AI summary
The control system of an internal combustion engine of the present invention comprises an S/V ratio changing mechanism able to change an S/V ratio of a combustion chamber and a detection device having an output value changing in accordance with a hydrogen concentration in exhaust gas, which increases along with an increase in the S/V ratio, the internal combustion engine being controlled by the output value of the detection device. Further, the output value of the detection device or a parameter relating to operation of the internal combustion engine is corrected in accordance with the S/V ratio of the above S/V ratio changing mechanism. Due to this, even if the hydrogen concentration in the exhaust gas increases along with an increase in the S/V ratio, the internal combustion engine can be suitably controlled.