Fuel injector diagnostics in a variable displacement engine

Patent metadata

Field	Value
Publication number	US-10408154-B2
Application number	US-201916363623-A
Country	US
Kind code	B2
Filing date	Mar 25, 2019
Priority date	Feb 2, 2017
Publication date	Sep 10, 2019
Grant date	Sep 10, 2019

Abstract

Methods and systems are provided for diagnosing a degraded fuel injector delivering undesired additional fuel in a variable displacement engine. In one example, a method includes, responsive to an indication of a cylinder air-fuel imbalance, deactivating a subset of cylinders of a multi-cylinder engine, performing a power balance test to determine an output of each cylinder after a duration of deactivation, and indicating that a deactivated cylinder has a degraded fuel injector responsive to the output being lower than a threshold output.

First claim

The invention claimed is:

1. A system, comprising:
an engine comprising a plurality of cylinders coupled to a crankshaft, each cylinder comprising a piston, one or more intake valves, one or more exhaust valves, and a fuel injector;
a fuel tank coupled to a fuel delivery system configured to pressurize fuel delivered to the fuel injectors;
one or more exhaust sensors coupled within an engine exhaust upstream of an emission control device; and
a controller holding executable instructions stored in non-transitory memory, that when executed, cause the controller to:
determine the presence of a rich fuel condition based on output from the one or more exhaust sensors;
selectively deactivate a subset of cylinders during a deactivation test period, including deactivating fuel injectors delivering fuel to the cylinder subset; and
seal the subset of cylinders, including deactivating the one or more intake valves and the one or more exhaust valves of each cylinder of the cylinder subset, in which the one or more intake valves and the one or more exhaust valves remain closed during the deactivation test period.

2. The system of claim 1 , further comprising an electric machine configured to rotate the crankshaft of the engine during the deactivation test period, and wherein current draw of the electric machine is measured during a compression stroke of each cylinder.

3. The system of claim 2 , wherein the controller further includes instructions to indicate that a fuel injector delivering fuel to a cylinder of the cylinder subset has not fully shut off responsive to the current draw during the compression stroke of the cylinder being greater than a threshold.

4. The system of claim 1 , wherein the controller further includes instructions to:
perform a first power balance test during the deactivation test period;
reactivate the subset of cylinders to expel any liquid fuel from the subset of cylinders;
deactivate the subset of cylinders and perform a second power balance test; and
indicate that a fuel injector delivering fuel to a cylinder of the cylinder subset has not fully shut off responsive to the first power balance test indicating low output of the cylinder and the second power balance test indicating average output of the cylinder.

5. The system of claim 4 , wherein the power balance test includes inferring a torque output of each cylinder and low output comprises the torque output being less than a threshold torque output.

6. The system of claim 1 , wherein the engine comprises a first engine bank and a second engine bank and the subset of cylinders includes the cylinders of the first engine bank.

7. The system of claim 1 , wherein the engine comprises a first engine bank and a second engine bank and the subset of cylinders includes cylinders of each engine bank.

Assignees

• Ford Global Tech Llc

Inventors

• Dudar Aed M

Classifications

• F02P5/045

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

• F02D41/26

  using computer, e.g. microprocessor · CPC title

• F02D41/221 Primary

  relating to the failure of actuators or electrically driven elements · CPC title

• F02D41/1497

  With detection of the mechanical response of the engine · CPC title

• F02D41/1443

  with one sensor per cylinder or group of cylinders · CPC title