Engine Control Purge Restriction for Catalyst Diagnosis
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Solution Overview
Problem
The existing control systems for engines inaccurately determine the abnormality of exhaust emission control catalysts due to oxygen consumption during deceleration fuel cutoff, leading to false determinations even when the catalyst is normal.
Innovation Solution
A control system that restricts the purge of evaporated fuel during the immediately previous deceleration fuel cutoff to prevent oxygen consumption, ensuring the stored oxygen amount in the exhaust emission control catalyst is maintained, thereby accurately determining catalyst abnormality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If purge is performed during deceleration fuel cutoff to suppress evaporated fuel overflow, then evaporated fuel overflow is suppressed, but stored oxygen amount in exhaust emission control catalyst is consumed leading to inaccurate abnormality determination
Solution Approach 1:
The control device performs preliminary action by restricting the purge operation before the abnormality determination process. By detecting that the engine operation has shifted from deceleration fuel cutoff to normal operation, the control device proactively restricts the purge to prevent oxygen consumption that would interfere with the upcoming abnormality determination, thereby eliminating the harmful effect before it occurs.
Solution Approach 2:
The control device dynamically adjusts the purge operation based on real-time engine operating conditions. The purge is restricted when the engine operation shifts from deceleration fuel cutoff to normal operation, and this restriction is lifted when the engine operation shifts back to deceleration fuel cutoff. This dynamic adjustment allows the system to optimize both evaporated fuel overflow suppression and abnormality determination accuracy under different operating conditions.
2Object-generated harmful factors
If purge gas is supplied to intake passage during deceleration fuel cutoff, then evaporated fuel is purified by exhaust emission control catalyst, but oxygen stored in catalyst is consumed reducing final integration value
Solution Approach 1:
The control device applies preliminary anti-action by restricting the purge operation before the abnormality determination process. By detecting that the engine operation has shifted from deceleration fuel cutoff to normal operation, the control device proactively restricts the purge to prevent oxygen consumption that would interfere with the upcoming abnormality determination, thereby eliminating the harmful effect before it occurs.
3Measurement precision
If purge is restricted during immediately previous deceleration fuel cutoff, then abnormality determination accuracy is maintained, but evaporated fuel overflow may occur
Solution Approach 1:
The control device dynamically adjusts the purge operation based on real-time engine operating conditions. The purge is restricted when the engine operation shifts from deceleration fuel cutoff to normal operation, and this restriction is lifted when the engine operation shifts back to deceleration fuel cutoff. This dynamic adjustment allows the system to optimize both evaporated fuel overflow suppression and abnormality determination accuracy under different operating conditions.
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 prevents degradation in accuracy of abnormality determination by maintaining the oxygen amount in the exhaust emission control catalyst, ensuring accurate assessment of catalyst health.
Implementation Method 1
During the deceleration fuel cutoff, oxygen is stored in the exhaust emission control catalyst, and normally during the deceleration fuel cutoff, the exhaust emission control catalyst reaches an oxygen-saturated state where oxygen cannot be stored anymore.
Implementation Method 2
a linear O2 sensor for detecting an oxygen concentration within exhaust gas for the purpose of performing a feedback control of an air-fuel ratio within a combustion chamber is provided upstream of the exhaust emission control catalyst, and an O2 sensor is provided downstream of the exhaust emission control catalyst.
Implementation Method 3
a purge gas containing evaporated fuel desorbed from a canister is supplied to an intake passage
Implementation Method 4
purge gas containing evaporated fuel desorbed from a canister is supplied to an intake passage
Implementation Method 5
An amount of excess fuel with respect to a stoichiometric amount in the injected fuel is oxidized and purified by the oxygen stored in the exhaust emission control catalyst.
Data Source
AI summary
A control system of an engine is provided. The control system includes a deceleration fuel cutoff module for performing a deceleration fuel cutoff when a deceleration fuel cutoff condition is satisfied in an engine decelerating state, a purge unit for purging by supplying a purge gas to an intake passage during the deceleration fuel cutoff, an exhaust emission control catalyst provided in an exhaust passage, an O2 sensor provided at a position of the exhaust passage downstream of the exhaust emission control catalyst, an abnormality determining module for determining an abnormality of the exhaust emission control catalyst, and a purge restricting module for restricting the purge during an immediately previous deceleration fuel cutoff.