Ignition diagnosis using ionization signal

• US 6,998,846 B2
• Filed: 06/11/2003
• Issued: 02/14/2006
• Est. Priority Date: 11/01/2002
• Status: Expired due to Fees

• Current Assignee: Visteon Global Technologies Incorporated (Visteon Corporation)
• Original Assignee: Visteon Global Technologies Incorporated (Visteon Corporation)
• Inventors: Daniels, Chao F., Zhu, Guoming G., Wang, Bruce, Gould, Kenneth L.
• Primary Examiner(s): DEB, ANJAN K
• Application Number:
  US10/458,718
• Publication Number:
  US 20040085070A1
• Time in Patent Office: 979 Days
• Field of Search: 324/391, 324/380, 324/384, 324/388, 324/393, 324/399, 123/406.13, 123/406.14, 73/350.8, 731/16
• US Class Current: 324/399
• CPC Class Codes: F01N 2430/00 Influencing exhaust purification, e.g. starting of catalytic reaction, filter regeneration, or the like, by controlling engine operating characteristics
• CPC Class Codes: F02D 2041/285 the sensor having a signal processing unit external to the engine control unit
• CPC Class Codes: F02D 2200/1015 Engines misfires
• CPC Class Codes: F02D 35/027 using knock sensors
• CPC Class Codes: F02M 26/01 Internal exhaust gas recirculation, i.e. wherein the residual exhaust gases are trapped in the cylinder or pushed back from the intake or the exhaust manifold into the combustion chamber without the use of additional passages
• CPC Class Codes: F02P 17/12 Testing characteristics of the spark, ignition voltage or current testing of sparking plugs H01T13/60
• CPC Class Codes: F02P 2017/125 Measuring ionisation of combustion gas, e.g. by using ignition circuits
• CPC Class Codes: F02P 2017/128 for knock detection
• CPC Class Codes: F02P 3/045 for control of the dwell or anti dwell time
• CPC Class Codes: F02P 3/0453 Opening or closing the primary coil circuit with semiconductor devices
• CPC Class Codes: F02P 3/051 Opening or closing the primary coil circuit with semiconductor devices
• CPC Class Codes: F02P 5/1506 with particular means during starting
• CPC Class Codes: F02P 5/1514 with means for optimising the use of registers or of memories, e.g. interpolation
• CPC Class Codes: F02P 5/1523 with particular laws of return to advance, e.g. step by step, differing from the laws of retard
• CPC Class Codes: F02P 5/1526 with means for taking into account incorrect functioning of the pinking sensor or of the electrical means
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

The present feature of the invention is generally directed to a subsystem of an ignition diagnostics and feedback control system using ionization current feedback. It utilizes the ionization signal from an ionization detection circuit to monitor ignition parameters, such as primary charge timing, primary charge duration, ignition/spark timing, and ignition/spark duration for future “smart” ignition system control. In addition, the ionization signal is also used to detect spark plug carbon fouling, as well as plug insulator overheating. These parameters can be monitored for every cylinder of the engine for each engine cycle.

Claims

1. A method of monitoring ignition efficiency, comprising the steps of:

monitoring a primary charge timing;

monitoring a primary charge duration;

monitoring an ignition timing;

monitoring an ignition duration; and

monitoring an ionization signal baseline by sending a warning signal indicating plug fouling or plug insulator overheating when said ionization baseline is elevated 20 percent or greater.

2. The method according to claim 1 wherein said step of monitoring a primary charge timing, comprises detecting a first rise in an ionization signal.

3. The method according to claim 2 wherein said step of monitoring a primary charge duration comprises:

detecting a first rise of said ionization signal;

detecting a stepped rise of said ionization signal; and

measuring a difference between said first rise and said stepped rise; and

wherein said step of monitoring an ignition duration comprises;

detecting a stepped rise of said ionization signal;

detecting when said ionization signal drops after said stepped rise; and

measuring a time difference between said signal drop and said step rise.

4. The method according to claim 3, further comprising a step of detecting plug fouling by detecting when an ionization baseline is elevated.

5. The method according to claim 3, further comprising:

detecting an open ionization circuit, comprising the steps of;

sampling a bias voltage; and

determining if said bias voltage is below a threshold.

6. The method according to claim 3, wherein said primary charge timing, said primary charge duration, said ignition timing, and said ignition duration are monitored for every cylinder of an engine.

7. The method according to claim 3, further comprising the steps of:

receiving a control signal;

discharging a pulse from a primary winding of an ignition coil;

charging a capacitor;

combusting an air/fuel mixture;

generating an ignition current, whereby said ignition current flows through a secondary winding of an ignition coil;

applying a bias voltage across ignition plug electrodes to generate ionization current, wherein said ionization current flows in a same direction as said ignition current; and

generating a mirror current, whereby said mirror current is proportional to said ionization current.

8. The method according to claim 4, further comprising:

detecting an open ionization circuit, comprising the steps of;

sampling a bias voltage; and

determining if said bias voltage is below a threshold.

9. The method according to claim 1 wherein said step of monitoring a primary charge duration comprises:

detecting a first rise of an ionization signal;

detecting a stepped rise of said ionization signal; and

measuring a difference between said first rise and said stepped rise.

10. The method according to claim 1 wherein said step of monitoring an ignition timing comprises detecting a stepped rise of an ionization signal.

11. The method according to claim 1 wherein said step of monitoring an ignition duration comprises:

detecting a stepped rise of an ionization signal;

detecting when said ionization signal drops after said stepped rise; and

measuring a time difference between said signal drop and said stepped rise.

12. The method according to claim 1 further comprising the step of monitoring preignition.

13. A method of detecting plug fouling, comprising the step of detecting when an ionization baseline is elevated, wherein said step of detecting when an ionization baseline is elevated further comprises sending a warning signal indicating plug fouling or plug insulator overheating when said ionization baseline is elevated 20 percent or greater.

14. The method according to claim 13, further comprising the steps of:

receiving a control signal;

discharging a pulse from a primary winding of an ignition coil;

charging a capacitor;

combusting an air/fuel mixture;

generating an ignition current, whereby said ignition current flows through a secondary winding of an ignition coil;

applying a bias voltage across an ignition plug electrodes to generate ionization current, wherein said ionization current flows in a same direction as said ignition current; and

generating a mirror current, whereby said mirror current is proportional to said ionization current.

15. The method according to claim 13, further comprising:

detecting an open ionization circuit, comprising the steps of;

sampling a bias voltage; and

determining if said bias voltage is below a threshold.

16. The method according to claim 13, further comprising:

detecting a shorted ionization circuit, comprising the step of;

determining if said bias voltage is above a second threshold.