Secondary Fluid Injection Control Using Exhaust Oxygen Sensor Feedback
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Solution Overview
Problem
Existing methods for adjusting secondary fluid injection in internal combustion engines based on engine operating parameters alone can result in either insufficient knock mitigation or excessive water condensation, leading to engine knock or oil dilution.
Innovation Solution
A method that uses an exhaust oxygen sensor to determine the actual amount of secondary fluid injected by measuring changes in pumping current between different reference voltages when only fuel and when fuel and secondary fluid are injected, allowing for precise adjustment based on engine operating conditions and desired secondary fluid composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If water injection amount is increased to mitigate knock, then knock control is improved, but water condensation and oil dilution occur
Solution Approach 1:
The patent uses feedback from oxygen sensors (lambda sensors) positioned in the exhaust system to monitor the actual amount of water injected into the cylinder. The controller compares the desired water injection amount with the actual amount detected by the sensors and adjusts the injection rate accordingly. This closed-loop feedback control prevents both insufficient knock mitigation and excessive water condensation leading to oil dilution.
2Object-generated harmful factors
If water injection amount is decreased to prevent oil dilution, then oil dilution is reduced, but knock mitigation becomes insufficient
Solution Approach 1:
The oxygen sensors provide real-time feedback on the actual water injection amount, allowing the controller to maintain the minimum necessary injection rate to prevent oil dilution while still achieving adequate knock control. The system dynamically adjusts the injection rate based on detected actual amounts rather than using fixed predetermined amounts.
3Ease of operation
If predetermined water injection amounts are used based on engine operating parameters, then control simplicity is maintained, but actual injection accuracy deteriorates
Solution Approach 1:
The system maintains control simplicity by using predetermined water injection amounts based on engine operating parameters as a baseline, but adds oxygen sensor feedback to measure and verify the actual injection amount. This combination allows the system to start with simple predetermined values while using feedback to correct deviations caused by variations in water quality, injection system performance, or changing operating conditions.
Solution Approach 2:
The patent replaces purely mechanical/measurement-based injection control with an electrochemical sensing system. Oxygen sensors (lambda sensors) use electrochemical reactions to detect the oxygen content in exhaust gases, which indirectly measures the actual water injection amount. This substitution provides precise measurement without complex mechanical measurement systems.
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 enables accurate control of secondary fluid injection, reducing engine knock and minimizing water condensation, thereby improving engine performance and preventing oil dilution.
Implementation Method 1
measuring changes in pumping current between different reference voltages when only fuel and when fuel and secondary fluid are injected
Data Source
AI summary
Methods and systems are provided for adjusting the amount of secondary fluid being injected into an engine. In one example, a method may include adjusting an amount of secondary fluid injected at an engine cylinder based on a secondary fluid injection amount estimated from outputs of an exhaust oxygen sensor. For example, the secondary fluid injection amount may be estimated based on a first change in pumping current of the exhaust oxygen sensor between a first and second reference voltage when only fuel is injected into the engine cylinder and a second change in pumping current of the exhaust oxygen sensor between the first and second reference voltage when fuel and the secondary fluid are injected into the engine cylinder.