Exhaust Catalyst Oxygen Estimation via O2 Sensor Feedback
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Solution Overview
Problem
Existing exhaust emission purification devices for engines face challenges in accurately estimating the accumulated oxygen amount in a catalyst during the termination of the reduction treatment, leading to inefficient air-fuel ratio control and potential unburnt gas production, especially when operating conditions change or the reduction treatment is forcibly terminated.
Innovation Solution
The device employs a secondary air injector and O2 sensor to estimate the accumulated oxygen amount by multiplying the count value with a correction coefficient derived from the O2 sensor output, allowing for accurate estimation and early termination of the reduction treatment while preventing unburnt gas production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the reduction treatment is performed by supplying rich fuel to reduce accumulated oxygen in the catalyst, then the air-fuel ratio control can be reverted to ordinary mode, but unburnt gas may be produced if the fuel is excessively rich
Solution Approach 1:
The system uses an O2 sensor to detect the air-fuel ratio in the downstream exhaust gas and feeds this information back to the ECU. The ECU adjusts the fuel injection amount based on the detected O2 concentration, ensuring the air-fuel ratio remains within the optimal range during reduction treatment and prevents excessive richness that would cause unburnt gas.
Solution Approach 2:
The system dynamically changes the fuel injection parameter (air-fuel ratio) based on the accumulated oxygen amount in the catalyst. By adjusting the fuel injection amount according to the O2 sensor feedback and accumulated oxygen data, the system optimizes the reduction treatment to prevent unburnt gas while effectively reducing catalyst oxygen accumulation.
2Measurement precision
If the accumulated oxygen amount is not accurately estimated, then the reduction treatment cannot be properly controlled, but the estimation becomes complex when operating conditions change or reduction treatment is forcibly terminated
Solution Approach 1:
The system employs feedback from the O2 sensor to continuously monitor exhaust gas composition and adjust the accumulated oxygen estimation. When operating conditions change or reduction treatment is forcibly terminated, the O2 sensor data provides real-time information that corrects the estimation without requiring complex additional sensors or calculation mechanisms.
Solution Approach 2:
The system uses the existing O2 sensor and ECU to perform both the reduction treatment control and the accumulated oxygen estimation. The ECU leverages the data already being collected for air-fuel ratio control to also estimate accumulated oxygen, eliminating the need for separate estimation hardware and reducing overall system complexity.
3Productivity
If the reduction treatment is terminated early to improve driving responsiveness, then control efficiency increases, but the accumulated oxygen amount may not be sufficiently reduced
Solution Approach 1:
The O2 sensor provides continuous feedback on the air-fuel ratio and oxygen concentration in the exhaust gas. This feedback allows the ECU to determine the optimal termination point for reduction treatment - when the accumulated oxygen has been sufficiently reduced and the air-fuel ratio stabilizes - ensuring both efficient control and reliable emission performance.
Solution Approach 2:
The system replaces complex mechanical timing mechanisms with electronic control based on O2 sensor feedback. The ECU automatically determines when to terminate reduction treatment based on real-time exhaust gas analysis, substituting mechanical timing constraints with intelligent, condition-based control that optimizes both efficiency and emission performance.
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 method enables accurate estimation of the accumulated oxygen amount, facilitating early termination of the reduction treatment and maintaining high emission performance by adjusting the air-fuel ratio, thus reducing unburnt gas production and improving control precision.
Implementation Method 1
an O2 sensor (52) which detects an air-fuel ratio
Implementation Method 2
a secondary air injector (1000) which is disposed in an upstream side of a catalyst (50) and injects secondary air into an exhaust path
Implementation Method 3
a catalyst (50) which is disposed at an exhaust pipe (32) of an engine (28)
Implementation Method 4
a reduction treatment means (118) which performs a rich injection after the secondary air injection
Data Source
AI summary
An exhaust emission purification control device for an engine that accurately estimates an accumulated oxygen amount of a catalyst at a terminating time of a reduction treatment which includes a secondary air injector that injects secondary air within an exhaust path, a sensor which detects an air-fuel ratio in a downstream side of a catylyst, a count-value accumulator which estimates an accumulated oxygen amount (a count value) in the catalyst during the secondary air injection, and a rich spike controller which performs rich injection after the secondary air injection. The device includes a count-value corrector that multiplies the count value after the secondary air injection by a correction coefficient derived from an output value SVO2 of the O2 sensor during termination of reduction treatment, so as to estimate the accumulated oxygen amount during the termination of the reduction treatment.