Method and system for variable displacement engine knock control

Patent metadata

Field	Value
Publication number	US-11204011-B2
Application number	US-201815985257-A
Country	US
Kind code	B2
Filing date	May 21, 2018
Priority date	May 21, 2018
Publication date	Dec 21, 2021
Grant date	Dec 21, 2021

Abstract

Methods and systems are provided for operating a variable displacement engine that includes a knock control system. Engine background noise levels for detecting engine knock may be the basis for determining whether or not the engine is operating in a cylinder deactivation mode. Further, select variable engine displacement modes may be avoided so that engine background noise level changes may be reduced to improve engine knock detection.

First claim

The invention claimed is:

1. An engine operating method, comprising:
operating a variable displacement engine;
changing from a first cylinder firing density to a second cylinder firing density via a controller based on maintaining fuel injector control actions for one or more engine cylinders that are performed during cylinder knock detection windows for active engine cylinders when the variable displacement engine is operated with the first cylinder firing density; and
adjusting a fuel injection split among direct and port injection upon changing from the first cylinder firing density to the second cylinder firing density based on a background noise within the cylinder knock detection windows in the first and second cylinder firing densities.

2. The method of claim 1 , where changing from the first cylinder firing density to the second cylinder firing density is further based on a change in vehicle operating conditions.

3. The method of claim 2 , where the change in vehicle operating conditions includes a change in engine speed or engine load.

4. The method of claim 1 , where changing from the first cylinder firing density to the second cylinder firing density includes reducing a firing density of the variable displacement engine.

5. The method of claim 1 , where changing the from the first cylinder firing density to the second cylinder firing density includes increasing a firing density of the variable displacement engine, and wherein the first and second cylinder firing densities include operating with both direct fuel injection and port fuel injection.

6. An engine operating method, comprising:
operating a variable displacement engine in a first mode where a fuel injector of the variable displacement engine is activated and determining a reference engine knock background noise level when the fuel injector is activated;
operating the variable displacement engine in a second mode where the fuel injector is commanded to be deactivated;
during the second mode, providing an indication of whether or not the fuel injector is deactivated as expected via a current engine knock background noise level relative to the reference engine knock background noise level and a controller; and
adjusting engine operation responsive to the indication via the controller.

7. The method of claim 6 , where adjusting engine operation includes enabling or disabling one or more variable displacement engine operating modes, wherein the fuel injector is coupled to a first cylinder, and wherein the reference engine knock background noise level is determined during a knock window for a second, different cylinder.

8. The method of claim 6 , where adjusting engine operation includes adjusting engine spark timing and fuel injection amounts.

9. The method of claim 6 , further comprising operating the variable displacement engine in a third mode where the fuel injector is commanded to be activated and providing a second indication of whether or not the fuel injector of the variable displacement engine is activated as expected via a second current engine knock background noise level relative to the reference engine knock background noise level, and adjusting engine operation responsive to the second indication, where the reference engine knock background noise level is based on output of an engine knock sensor, and where the reference engine knock background noise level includes noise from direct and port fuel injectors, wherein the fuel injector is one of the direct and port fuel injectors.

10. The method of claim 6 , further comprising integrating output of an engine knock sensor to determine the reference engine knock background noise level and entering or exiting a variable displacement engine cylinder operating mode to urge a change in the reference engine knock background noise level, and where the indication of whether or not the fuel injector is deactivated as expected is based on an urge to change the reference engine knock background noise level, and where the urge to change the reference engine knock background noise level is commanding one or more engine cylinders to activate or deactivate.

11. The method of claim 6 , further comprising determining the reference engine knock background noise level via an observer, where the observer provides an output that is dependent on engine speed, fuel injection timing, and fuel injection duration during a cylinder cycle.

12. The method of claim 11 , where the output of the observer is further dependent on a difference between a filtered integrated knock level change estimate and an integrated knock level change estimate.

13. The method of claim 6 , further comprising providing notification to vehicle occupants responsive to the indication.

14. A system, comprising:
a variable displacement engine; and
a controller including executable instructions stored in non-transitory memory to operate the variable displacement engine and change from a direct fuel injection only mode to a port fuel injection only mode in response to a determination that changing from operating the variable displacement engine with a first cylinder firing density to operating the variable displacement engine with a second cylinder firing density in the direct fuel injection only mode causes fuel injector control actions for one or more engine cylinders to be performed inside cylinder knock detection windows.

15. The system of claim 14 , further comprising additional instructions to change start of fuel injection timing of direct fuel injectors in response to a determination that changing from the first cylinder firing density to the second cylinder firing density causes fuel injector control actions for the one or more engine cylinders that are performed inside the cylinder knock detection windows for active engine cylinders to be performed outside the cylinder knock detection windows, and where the fuel injector control actions for the one or more engine cylinders is closing fuel injectors.

16. The system of claim 14 , where the fuel injector control actions are ceasing fuel injection via fuel injectors.

17. The system of claim 14 , where a first total number of engine cylinders are active when the variable displacement engine is operated with the first cylinder firing density, where a second total number of engine cylinders are active when the variable displacement engine is operated with the second cylinder firing density.

18. The system of claim 14 , where operating the variable displacement engine with the first cylinder firing density with the direct fuel injection only mode causes the fuel injector control actions for the one or more engine cylinders to be performed outside the cylinder knock detection windows.

Assignees

• Ford Global Tech Llc

Inventors

• Hakeem Mohannad
• Glugla Christopher Paul
• Kindree James Matthew
• Mcquinn Lee B

Classifications

• F02D41/30

  Controlling fuel injection {(F02D41/182, F02D41/24 take precedence)} · CPC title

• F02D41/0087

  Selective cylinder activation, i.e. partial cylinder operation (deceleration cut-off F02D41/123) · CPC title

• F02D2200/703

  Atmospheric pressure · CPC title

• F02D13/06 Primary

  Cutting-out cylinders · CPC title

• F01L13/0005

  Deactivating valves · CPC title