Engine Motoring Control for Catalyst-Safe A/F Sensor Learning
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Solution Overview
Problem
Existing vehicle control methods adversely affect exhaust performance when motoring an internal combustion engine due to oxygen inflow into the exhaust purification catalyst, and they also fail to accurately perform air fuel ratio learning.
Innovation Solution
A vehicle control method that stops fuel injection and motors the internal combustion engine using an electric motor generator, performing air fuel ratio learning only when the oxygen stored in the exhaust purification catalyst is below a certain threshold, thereby minimizing the impact on exhaust performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fuel injection is stopped and the internal combustion engine is motored by the electric motor generator, then air fuel ratio learning can be performed, but oxygen inflows into the exhaust purification catalyst which adversely affects exhaust performance
Solution Approach 1:
The control device checks the oxygen storage state of the exhaust purification catalyst before performing air fuel ratio learning through motoring. By preliminarily assessing whether the catalyst has sufficient oxygen storage capacity, the system determines if motoring can be safely performed without adversely affecting exhaust performance, thus preventing harmful effects before they occur.
Solution Approach 2:
The control device continuously monitors the oxygen storage state of the exhaust purification catalyst and uses this feedback information to decide whether to permit air fuel ratio learning. The system adjusts its operation based on the catalyst's real-time oxygen storage level, allowing motoring only when oxygen storage is sufficient, thereby maintaining both learning accuracy and exhaust performance.
2Reliability
If the oxygen storage amount in the exhaust purification catalyst is large, then the catalyst can effectively purify exhaust gas, but it takes much time to establish sufficient oxygen atmosphere for suppressing H2S emission during fuel cut control
Solution Approach 1:
The control device performs air fuel ratio learning when the oxygen storage amount in the catalyst is already sufficient, rather than waiting for oxygen atmosphere to develop during fuel cut control. This preliminary establishment of oxygen storage capacity through controlled motoring eliminates the time delay that would otherwise be required to build up oxygen atmosphere for H2S suppression.
Solution Approach 2:
The control device changes the operational parameters by performing motoring with fuel injection stopped, which allows precise control of oxygen flow to the catalyst. This parameter change enables the system to rapidly establish the desired oxygen storage state in the catalyst, avoiding the lengthy process of oxygen atmosphere development during conventional fuel cut control.
3Quantity of substance
If fuel cut control is executed to store oxygen in the exhaust gas purifying catalyst, then oxygen storage is sufficient for suppressing H2S emission, but the catalyst deterioration is promoted when the catalyst is under oxygen atmosphere at high temperature
Solution Approach 1:
The control device performs air fuel ratio learning when the catalyst oxygen storage ratio is already above the reference value, rather than executing additional fuel cut control to increase oxygen storage. This preliminary approach avoids subjecting the catalyst to prolonged high-temperature oxygen atmosphere that would accelerate deterioration, while still ensuring sufficient oxygen is available for H2S suppression.
Solution Approach 2:
The control device allows the oxygen storage amount to exceed the minimum required level by performing learning when the oxygen storage ratio is above the reference value, but avoids excessive fuel cut control that would create prolonged oxygen atmosphere at high temperatures. This partial action approach achieves sufficient oxygen storage without the harmful effects of excessive oxygen exposure at elevated temperatures.
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
Enables motoring the internal combustion engine without affecting exhaust performance and allows accurate air fuel ratio learning, reducing engine-out emissions and maintaining catalyst efficiency.
Implementation Method 1
a quantity of oxygen stored in an exhaust purification catalyst with respect to a maximum possible quantity of oxygen stored in the exhaust purification catalyst is calculated
Implementation Method 2
an air fuel ratio sensor upstream of the exhaust purification catalyst and configured to sense an air fuel ratio
Implementation Method 3
the internal combustion engine is structured to be motored by an electric motor generator
Data Source
Figure 1
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AI summary
A vehicle comprises: an internal combustion engine (7) which can be motorized by a generator (6); an exhaust catalyst device (24) which purifies the exhaust gas of the internal combustion engine (7); and an A/F sensor (47) which is located on the upstream side of the exhaust catalyst device (24) and detects an air-fuel ratio. When the oxygen storage amount of the exhaust catalyst device (24) increases but the effect on the exhaust performance on the downstream side of the exhaust catalyst device (24) is small, the fuel injection of the internal combustion engine (7) is stopped. The internal combustion engine (7) is motorized, and air-fuel ratio learning for learning the detection value of the A/F sensor (47) is performed. This makes it possible to motorize the internal combustion engine (7) without causing deterioration in exhaust performance. Further, the air-fuel ratio learning can be performed without causing deterioration in exhaust performance.