Control system for variable displacement engine

Patent metadata

Field	Value
Publication number	US-2020191075-A1
Application number	US-201816218098-A
Country	US
Kind code	A1
Filing date	Dec 12, 2018
Priority date	Dec 12, 2018
Publication date	Jun 18, 2020
Grant date	—

Abstract

A vehicle includes a variable displacement engine and a controller. The variable displacement engine has a plurality of cylinders and is configured to operate at a commanded air-fuel ratio. The controller is programmed to, in response to a command to perform a diagnostic test, operate the engine such that each of the cylinders is shut down for a portion of the diagnostic test while one or more of the remainder of the cylinders remain operating. The controller is further programmed to, in response to a deviation from the commanded air-fuel ratio exceeding a threshold while a first of the cylinders is shut down during the diagnostic test and a subsequent command to decrease the number of operating cylinders, shut down one or more of the plurality of cylinders other than the first of the cylinders.

First claim

What is claimed is:

1 . A vehicle comprising:
a variable displacement engine having a plurality of cylinders and configured to operate at a commanded air-fuel ratio; and a controller programmed to,
in response to a command to perform a diagnostic test, operate the engine such that each of the cylinders is shut down for a portion of the diagnostic test while one or more of the remainder of the cylinders remain operating, and
in response to a deviation from the commanded air-fuel ratio exceeding a threshold while a first of the cylinders is shut down during the diagnostic test and a subsequent command to decrease the number of operating cylinders, shut down one or more of the plurality of cylinders other than the first of the cylinders.

2 . The vehicle of claim 1 , wherein the controller is further programmed to, in response to the deviation from the commanded air-fuel ratio exceeding the threshold while the first of the cylinders is shut down during the diagnostic test, issue a notification that the valves of at least one of the cylinders are not deactivating during a mode where one or more of the cylinders are shut down.

3 . The vehicle of claim 1 , wherein the controller is further programmed to, in response to the deviation from the commanded air-fuel ratio exceeding the threshold while the first of the cylinders is shut down during the diagnostic test, a second deviation from the commanded air-fuel ratio exceeding the threshold while a second of the cylinders is shut down during the diagnostic test, and the subsequent command to decrease the number of operating cylinders, override shutting down any of the plurality of cylinders.

4 . The vehicle of claim 1 , wherein the controller is further programmed to operate each of the cylinders individually prior to the diagnostic test and set a fuel flow to each cylinder such that each cylinder operates at the commanded air-fuel ratio.

5 . The vehicle of claim 4 , wherein the controller is further programmed to, in response to a deviation of an air-fuel ratio of one of the plurality of cylinders from the commanded air-fuel ratio exceeding a threshold within a predetermined period of time after setting the fuel flow to each of the cylinders, issue a notification that one of the cylinders is defective.

6 . The vehicle of claim 1 further comprising an oxygen sensor that is configured to measure the oxygen content within exhaust gas produced by the engine, and wherein the controller is configured to adjust the air-fuel ratio of the engine to the commanded air-fuel ratio based on the measured oxygen content within the exhaust gas.

7 . The vehicle of claim 6 further comprising an exhaust gas conduit that is configured to channel exhaust gas from the plurality of cylinders to a catalyst, and wherein the oxygen sensor is disposed within the conduit between the plurality of cylinders and the catalyst.

8 . A method of operating a vehicle engine having a plurality of cylinders comprising:
operating the engine during a diagnostic test such that each of the cylinders is shut down for a portion of the diagnostic test while one or more of the remainder of the cylinders remain operating, and in response to a deviation from a commanded air-fuel ratio exceeding a threshold while a first of the cylinders is shut down during the diagnostic test and a subsequent command to decrease the number of operating cylinders, shutting down one or more of the plurality of cylinders other than the first of the cylinders.

9 . The method of claim 8 further comprising:
in response to the deviation from the commanded air-fuel ratio exceeding the threshold while the first of the cylinders is shut down during the diagnostic test, issue a notification that the valves of at least one of the cylinders are not deactivating during a mode where one or more of the cylinders are shut down.

10 . The method of claim 8 further comprising:
in response to the deviation from the commanded air-fuel ratio exceeding the threshold while the first of the cylinders is shut down during the diagnostic test, a second deviation from the commanded air-fuel ratio exceeding the threshold while a second of the cylinders is shut down during the diagnostic test, and the subsequent command to decrease the number of operating cylinders, override shutting down any of the plurality of cylinders.

11 . The method of claim 8 further comprising:
operating each of the cylinders individually prior to the diagnostic test to determine a measured air-fuel ratio of each cylinder.

12 . The method of claim 11 further comprising:
adjusting a fuel flow to each cylinder such that each cylinder operates at the commanded air-fuel ratio.

13 . The method of claim 12 further comprising:
in response to a deviation of an air-fuel ratio of one of the plurality of cylinders from the commanded air-fuel ratio exceeding a threshold within a predetermined period of time after adjusting the fuel flow to each of the cylinders, issuing a notification that one of the cylinders is defective.

14 . A vehicle comprising:
an engine having plurality cylinders and configured to operate at a commanded air-fuel ratio; and a controller programmed to,
in response to a command to perform a diagnostic test, operate the engine such that each of the cylinders is shut down for a portion of the diagnostic test while one or more of the remainder of the cylinders remain operating, and
in response to a deviation from the commanded air-fuel ratio exceeding a threshold while a first of the cylinders is shut down during the diagnostic test and a subsequent command to operate the engine in a skip-fire mode, shut down one or more of the plurality of cylinders other than the first of the cylinders.

15 . The vehicle of claim 14 , wherein the controller is further programmed to, in response to the deviation from the commanded air-fuel ratio exceeding the threshold while the first of the cylinders is shut down during the diagnostic test, issue a notification that the valves of at least one of the cylinders are not deactivating during the skip-fire mode.

16 . The vehicle of claim 14 , wherein the controller is further programmed to, in response to the deviation from the commanded air-fuel ratio exceeding the threshold while the first of the cylinders is shut down during the diagnostic test, a second deviation from the commanded air-fuel ratio exceeding the threshold while a second of the cylinders is shut down during the diagnostic test, and the subsequent command to operate the engine in a skip-fire mode, override operating in the skip-fire mode.

17 . The vehicle of claim 14 , wherein the controller is further programmed to operate each of the cylinders individually prior to the diagnostic test and set a fuel flow to each cylinder such that each cylinder operates at the commanded air-fuel ratio.

18 . The vehicle of claim 17 , wherein the controller is further programmed to, in response to a deviation of an air-fuel ratio of one of the plurality of cylinders from the commanded air-fuel ratio exceeding a threshold within a predetermined period of time after setting the fuel flow to each of the cylinders, issue a notification that one of the cylinders is defective.

19 . The vehicle of claim 14 further comprising an oxygen sensor that is configured to measure the oxygen content within exhaust gas produced by the engine, and wherein the controller is configured to adjust the air-fuel ratio of the engine to the commanded air-fuel ratio based on the measured oxygen content wit

Assignees

• Denso Int America Inc

Inventors

• Szczepanski Edward

Classifications

• Y02A50/20

  Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters · CPC title

• F01L2800/11

  Fault detection, diagnosis · CPC title

• F01L2001/186

  Split rocking arms, e.g. rocker arms having two articulated parts and means for varying the relative position of these parts or for selectively connecting the parts to move in unison · CPC title

• F01L2013/105

  Hydraulic motors · CPC title

• F01L1/185

  Overhead end-pivot rocking arms · CPC title