Laser ignition system based diagnostics

Patent metadata

Field	Value
Publication number	US-2015198136-A1
Application number	US-201414152851-A
Country	US
Kind code	A1
Filing date	Jan 10, 2014
Priority date	Jan 10, 2014
Publication date	Jul 16, 2015
Grant date	—

Abstract

Methods and systems are provided for using an engine laser ignition system to perform a visual inspection of an engine and diagnose various cylinder components and conditions based on engine positional measurements. Laser pulses may be emitted at a lower power level during an intake and/or exhaust stroke to illuminate a cylinder interior while a photodetector captures images of the cylinder interior. Additionally, laser pulses may be emitted at a higher power level to initiate cylinder combustion while the photodetector captures images of the cylinder interior using the light generated during cylinder combustion.

First claim

1 . A method for an engine, comprising:
over an engine cycle, operating a laser ignition device in each engine cylinder; identifying a piston position in each cylinder based on the operating; and indicating degradation of a crankshaft based on a piston position of each cylinder.

2 . The method of claim 1 , wherein identifying a piston position in each cylinder based on the operating includes:
for each cylinder, sensing light reflected off a top surface of the piston; and estimating the piston position based on a time elapsed between the operating of the laser ignition device and the sensing of the light.

3 . The method of claim 1 , wherein the operating includes operating the laser ignition device at a lower power in one of an intake stroke or an exhaust stroke of each engine cylinder, the lower power below a threshold power required to initiate cylinder combustion.

4 . The method of claim 1 , wherein the operating includes operating the laser ignition device at a higher power in a compression stroke of each cylinder, the higher power above a threshold power required to only illuminate the cylinder.

5 . The method of claim 1 , wherein the indicating includes indicating crankshaft degradation based on a difference between the piston position of a first cylinder relative to a second cylinder being higher than a threshold amount, the second cylinder selected based on the first cylinder.

6 . The method of claim 1 , wherein indicating degradation of the crankshaft includes indicating that the crankshaft is twisted.

7 . The method of claim 1 , wherein indicating degradation of the crankshaft includes indicating that the camshaft is broken.

8 . A method for an engine, comprising:
over an engine cycle, operating a laser ignition device in each engine cylinder; identifying a cylinder valve position in each cylinder based on the operating; and indicating degradation of a camshaft based on a valve position of each cylinder.

9 . The method of claim 8 , wherein the cylinder valve is a cylinder intake valve.

10 . The method of claim 9 , wherein identifying a valve position in each cylinder based on the operating includes:
for each cylinder, sensing light reflected off the cylinder valve; and estimating the camshaft position based on a time elapsed between the operating of the laser ignition device and the sensing of the light.

11 . The method of claim 10 , wherein the operating includes operating the laser ignition device at a lower power in one of an intake stroke or an exhaust stroke of each engine cylinder, the lower power below a threshold power required to initiate cylinder combustion.

12 . The method of claim 10 , wherein the operating includes operating the laser ignition device at a higher power in a compression stroke of each cylinder, the higher power above a threshold power required to only illuminate the cylinder.

13 . The method of claim 10 , wherein the indicating includes indicating camshaft degradation based on a difference between the camshaft position of a first cylinder and a second cylinder being higher than a threshold amount, the second cylinder selected based on the first cylinder.

14 . The method of claim 8 , wherein indicating degradation of the camshaft includes indicating that the camshaft is twisted.

15 . The method of claim 8 , wherein indicating degradation of the camshaft includes indicating that an electric cam system coupled to the camshaft is degraded.

16 . A method, comprising:
operating a laser ignition device in an engine cylinder; identifying each of a cylinder piston position and a cylinder valve position based on the operating; and indicating misalignment of a crankshaft relative to a camshaft based on a deviation of the identified cylinder valve position from an expected valve position, the expected valve position based on the identified cylinder piston position.

17 . The method of claim 16 , wherein the cylinder valve position includes a cylinder intake valve position.

18 . The method of claim 17 , wherein the identifying includes:
identifying the cylinder valve position based on a time taken to detect a laser signal reflected off of a cylinder valve; and identifying the cylinder piston position based on a time taken to detect a laser signal reflected off the cylinder piston.

19 . The method of claim 16 , wherein operating the laser ignition device includes operating at a power level lower than a threshold power required for initiating cylinder combustion.

20 . The method of claim 17 , wherein indicating misalignment includes setting a diagnostic code, and in response to the indication, advancing an intake cam timing to compensate for degraded flow through the cylinder intake valve.

Assignees

• Ford Global Tech Llc

Inventors

• Martin Douglas Raymond
• Miller Kenneth James

Classifications

• G01S17/06

  Systems determining position data of a target · CPC title

• G01M15/06

  by monitoring positions of pistons or cranks · CPC title

• F02P23/04 Primary

  Other physical ignition means, e.g. using laser rays · CPC title

• F02C7/264

  Ignition · CPC title

• G01N2201/06113

  Coherent sources; lasers · CPC title