System and method for selective cylinder deactivation

Patent metadata

Field	Value
Publication number	US-2016003168-A1
Application number	US-201514602353-A
Country	US
Kind code	A1
Filing date	Jan 22, 2015
Priority date	Jul 7, 2014
Publication date	Jan 7, 2016
Grant date	—

Abstract

Embodiments for operating an engine with skip fire are provided. In one example, a method comprises during a skip fire mode or during a skip fire mode transition, port injecting a first fuel quantity to a cylinder of an engine, the first fuel quantity based on a first, predicted air charge amount for the cylinder and lean of a desired air-fuel ratio, and direct injecting a second fuel quantity to the cylinder, the second fuel quantity based on the first fuel quantity and a second, calculated air charge amount for the cylinder.

First claim

1 . A method, comprising:
during a skip fire mode or skip fire mode transition,
port injecting a first fuel quantity to an engine cylinder, the first fuel quantity based on a first, predicted air charge amount for the cylinder and lean of a desired air-fuel ratio; and
direct injecting a second fuel quantity to the cylinder, the second fuel quantity based on the first fuel quantity and a second, air charge amount for the cylinder.

2 . The method of claim 1 , wherein the first fuel quantity is lean of the desired air-fuel ratio by an amount corresponding to a maximum possible deviation from the first, predicted air charge amount for current engine operating conditions, and further by an amount based on one or more of detected engine knock and intake throttle position.

3 . The method of claim 1 , wherein direct injection of the second fuel quantity occurs after port injection of the first fuel quantity.

4 . The method of claim 3 , wherein the first fuel quantity is injected prior to intake valve opening and the second fuel quantity is injected near intake valve closing, after the injection of the first fuel quantity.

5 . The method of claim 1 , wherein the skip fire mode includes engine operation with at least one remaining cylinder of the engine deactivated.

6 . The method of claim 1 , wherein the skip fire mode includes transition into the skip fire mode, where the engine transitions from firing all cylinders to firing only a subset of the cylinders of the engine.

7 . The method of claim 1 , wherein the skip fire mode includes transition out of the skip fire mode, where the engine transitions from firing only a subset of cylinders of the engine to firing all cylinders of the engine.

8 . The method of claim 1 , wherein the first, predicted air charge amount is an air charge amount for the cylinder predicted prior to intake valve opening, and wherein the second, calculated air charge amount is an air charge amount for the cylinder calculated at intake valve closing.

9 . The method of claim 8 , wherein the desired air-fuel ratio is a first desired air-fuel ratio calculated based on the first, predicted air charge amount, and wherein direct injecting the second fuel quantity to the cylinder comprises direct injecting the second fuel quantity to bring an overall cylinder air-fuel ratio to a second desired air-fuel ratio, the second desired air-fuel ratio calculated based on the second, calculated air charge amount.

10 . The method of claim 1 , wherein the cylinder is a first cylinder scheduled to be fired in a commanded firing order of the engine, and further comprising:
determining if combustion occurred in the first cylinder based on feedback from an ionization sensor; and if combustion does not occur in the first cylinder as commanded, adjusting the commanded firing order of the engine to fire a second cylinder, the second cylinder originally scheduled to be skipped in the commanded firing order.

11 . A method, comprising:
during a skip fire mode or a skip fire mode transition,
injecting a first fuel quantity to a first engine cylinder, the first fuel quantity based on a first air charge amount for the first cylinder and a desired air-fuel ratio; and
injecting a second fuel quantity to a second engine cylinder, the second fuel quantity based on the first fuel quantity and a second air charge amount for the first cylinder.

12 . The method of claim 11 , wherein the skip fire mode includes engine operation with at least one remaining cylinder of the engine deactivated.

13 . The method of claim 11 , wherein the skip fire mode includes transition into the skip fire mode, where the engine transitions from firing all cylinders to firing only a subset of the cylinders of the engine.

14 . The method of claim 11 , wherein the skip fire mode includes transition out of the skip fire mode, where the engine transitions from firing only a subset of cylinders of the engine to firing all cylinders of the engine.

15 . The method of claim 11 , wherein the first air charge amount is a predicted air charge amount for the first cylinder predicted prior to an intake valve of the first cylinder opening, and wherein the second air charge amount is a calculated air charge amount for the first cylinder calculated at a subsequent closing of the intake valve of the first cylinder.

16 . The method of claim 15 , wherein the second fuel quantity is further based on a third air charge amount predicted for the second cylinder and a second desired air-fuel ratio.

17 . The method of claim 11 , wherein the injecting of the first fuel quantity and the injecting of the second fuel quantity each occur via port injection.

18 . A system, comprising:
an engine having a plurality of cylinders; a port fuel injection system to port inject fuel to each cylinder of the plurality of cylinders; a direct fuel injection system to direct inject fuel to each cylinder of the plurality of cylinders; a spark ignition system to initiate combustion in each cylinder of the plurality of cylinders, including one or more ionization sensors to detect occurrence of combustion events in the plurality of cylinders; and a controller including non-transitory instructions to:
determine a commanded firing order of the engine during a skip fire mode, where at least a first cylinder of the plurality of cylinders is scheduled to be fired and at least a second cylinder of the plurality of cylinders is scheduled to be skipped; and
during firing of the first cylinder, activate the port fuel injection system to port inject a first fuel quantity to the first cylinder during a first, earlier portion of an engine cycle, activate the direct fuel injection system to direct inject a second fuel quantity to the first cylinder during a second, later portion of the engine cycle, and activate the spark ignition system to initiate combustion in the first cylinder, where the first fuel quantity is lean of a first desired air-fuel ratio for the first cylinder that is based on an estimated air charge amount for the first cylinder, and the second fuel quantity brings on overall air-fuel ratio for the first cylinder to a second, desired air-fuel ratio for the first cylinder that is based on an updated air charge amount for the first cylinder.

19 . The system of claim 18 , wherein the controller includes further instructions to:
determine if combustion occurred in the first cylinder via feedback from the one or more ionization sensors; if combustion does not occur in the first cylinder, adjust the commanded firing order to fire the second cylinder; and if combustion does occur in the first cylinder, maintain the commanded firing order to skip the second cylinder.

20 . The system of claim 19 , wherein the commanded firing order of the engine is based on an original firing order of the engine in a non-skip fire mode, a number of cylinders to be skipped during the skip fire mode, and which cylinders of the plurality of cylinders were fired in a previous engine cycle, where the number of cylinders to be skipped is based on engine load.

Assignees

• Ford Global Tech Llc

Inventors

• Leone Thomas G
• Rollinger John Eric
• Jankovic Mrdjan J
• Boyer Brad Alan

Classifications

• F02D41/3017

  characterised by the mode(s) being used · CPC title

• F02D35/021

  using an ionic current sensor · CPC title

• F02D37/02

  one of the functions being ignition · CPC title

• F02P5/045

  combined with electronic control of other engine functions, e.g. fuel injection (in general F02D37/02) · CPC title

• F02M69/046

  for injecting into both the combustion chamber and the intake conduit · CPC title