LASER IGNITION SYSTEM BASED DIAGNOSTICS

• US 20150198136A1
• Filed: 01/10/2014
• Published: 07/16/2015
• Est. Priority Date: 01/10/2014
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Martin, Douglas Raymond, Miller, Kenneth James
• Granted Patent: US 9,243,603 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: F02D 35/022 using an optical sensor, e.g. in-cylinder light probe
• CPC Class Codes: F02D 41/009 using means for generating position or synchronisation signals
• CPC Class Codes: F02D 41/22 Safety or indicating devices for abnormal conditions in air/fuel ratio feedback systems F02D41/1495, in electric control linkage F02D11/107, in purge control systems F02M25/0809
• CPC Class Codes: F02P 17/00 Testing of ignition installations, e.g. in combination with adjusting testing fuel injection apparatus F02M65/00; testing ignition installations in general F23Q23/00; Testing of ignition timing in compression-ignition engines
• CPC Class Codes: F02P 23/04 Other physical ignition means, e.g. using laser rays
• CPC Class Codes: G01M 15/06 by monitoring positions of pistons or cranks
• CPC Class Codes: G01N 2201/06113 Coherent sources; lasers
• CPC Class Codes: G01N 2201/0697 Pulsed lasers
• CPC Class Codes: G01S 17/06 Systems determining position data of a target
• CPC Class Codes: G01S 17/10 using transmission of interrupted, pulse-modulated waves determination of distance by phase measurements G01S17/32
• CPC Class Codes: G01S 17/88 Lidar systems specially adapted for specific applications
• CPC Class Codes: G01S 7/497 Means for monitoring or calibrating
• CPC Class Codes: Y02T 10/40 Engine management systems

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.

Claims

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.