Method and system for air-fuel ratio control

An air-fuel ratio and fuel technology, which is applied in fuel injection control, electrical control, charging system, etc., can solve problems such as emission problems, complex calculations, and damage to the output of oxygen sensors, so as to reduce emissions, improve exhaust emissions and improve engine performance. performance, and the effect of improving fuel efficiency

Inactive Publication Date: 2017-12-22
FORD GLOBAL TECH LLC
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AI Technical Summary

Problems solved by technology

Also, when fuel pulses are scheduled through the injector, the purge of fuel vapors and use of positive crankcase ventilation (PCV) can further corrupt the oxygen sensor output, requiring complex calculations to compensate for ingested hydrocarbons
If AFR monitoring is scheduled with extraction or PCV disabled, there may be limited opportunities for AFR monitoring
On the other hand, if extraction is disabled to accomplish AFR monitoring, the fuel vapor canister may not be cleaned effectively, causing emissions issues

Method used

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  • Method and system for air-fuel ratio control
  • Method and system for air-fuel ratio control
  • Method and system for air-fuel ratio control

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Embodiment Construction

[0022] The following description relates to systems and methods for detecting and correcting air-fuel ratio imbalances and injector errors during DFSO. figure 1 A single cylinder of an engine including an exhaust gas sensor upstream of an emission control device is shown. figure 2 An engine, transmission, and other vehicle components are depicted. image 3 A sample V-8 engine is shown with a pair of cylinder banks, an exhaust manifold, and an exhaust sensor. Figure 4 A method for determining the status of a DFSO is shown. Figure 5 A method of initiating open loop air-fuel ratio control during DFSO is shown. Image 6 An example method is presented for performing open loop air-fuel ratio control based on inter-cylinder air-fuel ratio corrections. Figure 7 Sample graph data showing groups of two consecutive fuel pulses injected into cylinders with different pulse widths and learned measurements for inter-cylinder air-fuel variation based on lambda value during open-loop ai...

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Abstract

Methods and systems are provided for learning fuel injector error for cylinder groups during a deceleration fuel shut-off (DFSO), where all cylinders of an engine are deactivated, sequentially firing each cylinder of a cylinder group, each cylinder fueled via consecutive first and second fuel pulses of differing fuel pulse width from an injector. Based on a lambda deviation between the first and second pulses, a fuel error for the injector and an air-fuel ratio imbalance for each cylinder is learned. Alternatively or additionally, a difference in crankshaft acceleration between the first and second pulses relative to the expected deviation may be used to learn torque error, and adjust fuel injector error and air-ratio imbalance for each cylinder.

Description

technical field [0001] The present description generally relates to methods and systems for controlling a vehicle engine to monitor air-fuel ratio imbalances during deceleration fuel cutoff (DFSO) conditions. Background technique [0002] Engine parameters such as air-fuel ratio (AFR) can be controlled to ensure improved engine performance, efficient use of exhaust catalysts and reduced exhaust emissions. In particular, engine emissions may be degraded if engine exhaust is not as rich or lean as expected due to variations in the engine air-fuel ratio between cylinders of the engine. Additionally, there may be a torque imbalance between the engine cylinders, which can lead to NVH issues. [0003] One way to determine changes in air-fuel ratio between engine cylinders is to sense engine exhaust via an oxygen sensor. Additionally or alternatively, crankshaft acceleration may be estimated at desired AFR. Fuel and / or charge air parameters may then be adjusted based on the chan...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): F02D41/12
CPCF02D41/126F02D13/0207F02D13/06F02D17/02F02D41/0085F02D41/0087F02D41/123F02D41/1454F02D41/1497F02D41/2454F02D41/2467F02D41/3076F02D41/3094F02D41/402F02D2200/1012F02M65/001Y02T10/12Y02T10/40F02M65/00
Inventor G·苏尼拉I·H·马克伊A·P·R·朗高H·贾姆莫西R·R·杰兹M·I·克鲁塞恩S·B·史密斯
Owner FORD GLOBAL TECH LLC
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