Method and system for pre-ignition control

Patent metadata

Field	Value
Publication number	US-9695755-B2
Application number	US-201615226623-A
Country	US
Kind code	B2
Filing date	Aug 2, 2016
Priority date	Jan 23, 2014
Publication date	Jul 4, 2017
Grant date	Jul 4, 2017

Abstract

Methods and systems are provided for addressing pre-ignition occurring while operating with blow-though air delivery. A variable cam timing device used to provide positive intake to exhaust valve overlap is adjusted in response to an indication of pre-ignition to transiently reduce valve overlap. Pre-ignition mitigating load limiting and enrichment applied during a blow-through mode is adjusted differently from those applied when blow-through air is not being delivered.

First claim

The invention claimed is:

1. A method for a boosted engine, comprising:
while operating in a blow-through mode, reducing valve overlap of an intake and exhaust valve by adjusting a valve actuator in response to an indication of pre-ignition and adjusting ignition timing responsive to knock, pre-ignition indicated in response to knock sensor output before a cylinder spark event, knock indicated in response to knock sensor output after the cylinder spark event,
wherein operating in a blow-through mode includes directing intake air from an intake manifold, downstream of a compressor, to an exhaust manifold, upstream of a turbine, via positive valve overlap around TDC at an end of an exhaust stroke through one or more engine cylinders, an amount of the positive valve overlap based on operating conditions,
wherein directing intake air via positive valve overlap includes adjusting a variable cam timing device to adjust an intake or exhaust valve timing of the one or more cylinders from a first valve timing corresponding to no positive valve overlap to a second valve timing corresponding to positive intake valve to exhaust valve overlap, and
wherein reducing valve overlap in response to the indication of pre-ignition includes, in response to the indication of pre-ignition in any engine cylinder, adjusting the variable cam timing device to adjust the intake or exhaust valve timing of all engine cylinders from the second valve timing towards the first valve timing, an amount of valve overlap reduction increased as the indication of pre-ignition increases.

2. The method of claim 1 , wherein the operating conditions include operator torque demand and turbine speed, and wherein operating in the blow-through mode is responsive to an operator pedal tip-in.

3. The method of claim 2 , wherein operating in the blow-through mode is responsive to a turbine speed being lower than a threshold speed at a time of the operator pedal tip-in.

4. The method of claim 3 , further comprising operating in the blow-through mode until the turbine speed reaches the threshold speed.

5. The method of claim 1 , further comprising in response to the indication of pre-ignition in any engine cylinder, adjusting the variable cam timing device to adjust the intake or exhaust valve timing of all engine cylinders.

6. The method of claim 1 , further comprising during the blow-through mode and when directing intake air from the intake manifold to the exhaust manifold via positive valve overlap, adjusting a fuel injection amount based on an amount of air directed via the positive valve overlap.

7. The method of claim 6 , wherein the fuel injection amount is adjusted to maintain an exhaust air-to-fuel ratio at approximately stoichiometry.

8. The method of claim 1 , further comprising, responsive to indication of pre-ignition during a non-blow-through operating mode, limiting an engine load.

9. The method of claim 8 , where limiting the engine load includes reducing an intake throttle opening.

10. The method of claim 8 , where limiting the engine load includes adjusting a waste-gate position.

Assignees

• Ford Global Tech Llc

Inventors

• Glugla Chris Paul
• Baskins Robert Sarow
• Kindree James Matthew
• Pietrzyk Paul A
• Guerrier Mark Paul
• Sanghvi Rama

Classifications

• Y02T10/12

  Improving ICE efficiencies · CPC title

• Y02T10/26

  Cross-Sectional Technologies · mapped topic

• F02D41/10

  for acceleration · CPC title

• F02P5/1528

  for turbocompressed engine · CPC title

• F02D35/027

  using knock sensors · CPC title