Method and system for knock control

Patent metadata

Field	Value
Publication number	US-9284909-B2
Application number	US-201313975063-A
Country	US
Kind code	B2
Filing date	Aug 23, 2013
Priority date	Aug 23, 2013
Publication date	Mar 15, 2016
Grant date	Mar 15, 2016

Abstract

Methods and systems are provided for improving engine knock tolerance, in particular when rapidly ramping in LP-EGR from low levels of EGR. Until a desired LP-EGR rate is achieved, fuel may be delivered as a split injection with at least an intake stroke injection and a compression stroke injection to compensate for the transport delay in EGR filling the intake system. Subsequently, single fuel injection may be resumed.

First claim

The invention claimed is:

1. An engine method, comprising:
during a first mode, operating with a lower than threshold EGR rate, and in response to a tip-in to higher load, maintaining single fuel injection per cycle and increasing opening of an LP-EGR valve; and
during a second mode, operating with the lower than threshold EGR rate, and in response to a tip-in to higher load, operating with split fuel injection per cycle, and increasing opening of the LP-EGR valve.

2. The method of claim 1 , wherein during the first mode, the engine is operating within a knock limit at the higher load and wherein during the second mode, the engine is operating beyond the knock limit at the higher load.

3. The method of claim 1 , wherein during both the first and second modes, a combustion air-fuel ratio is maintained at or around stoichiometry.

4. The method of claim 1 , wherein during the first mode, an EGR error is lower than a threshold and wherein during the second mode, the EGR error is higher than the threshold, the EGR error based on a difference between a target EGR and a delivered EGR.

5. The method of claim 1 , wherein the lower than threshold EGR rate during the first mode is a fixed EGR rate relative to airflow, and wherein the lower than threshold EGR rate during the second mode is a zero EGR rate.

Assignees

• Ford Global Tech Llc

Inventors

• Wooldridge Steven
• Surnilla Gopichandra
• Boyer Brad Alan
• Hilditch James Alfred
• Shelby Michael Howard
• Glugla Chris Paul
• Petersen Benjamin Richard

Classifications

• F02D41/3023

  a mode being the stratified charge spark-ignited mode · CPC title

• F02D41/005

  according to engine operating conditions · CPC title

• F02D41/12

  for deceleration {(F02D41/0005, F02D41/107 take precedence)} · CPC title

• F02D41/10

  for acceleration · CPC title

• F02M25/0709

  Mechanical Engineering · mapped topic