Apparatus and method for testing an ignition coil and spark plug

• US 6,426,626 B1
• Filed: 03/29/1999
• Issued: 07/30/2002
• Est. Priority Date: 03/31/1998
• Status: Expired due to Fees

• Current Assignee: Comau Incorporated (Stellantis NV)
• Original Assignee: Progressive Tool & Industries, Co.
• Inventors: Kravis, Steven F.
• Primary Examiner(s): Le, N.
• Assistant Examiner(s): Deb, Anjan K
• Application Number:
  US09/280,276
• Time in Patent Office: 1,219 Days
• Field of Search: 324/379, 324/378, 324/388, 324/380, 324/389, 324/393, 324/402, 324/686, 324/399, 731/173, 123/481, 123/478, 123/406.14
• US Class Current: 324/388
• 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 3/02 having inductive energy storage, e.g. arrangements of induction coils ignition coils structurally combined with sparking plugs F02P13/00; constructional details of ignition coils H01F38/12
• CPC Class Codes: F02P 3/0861 Closing the discharge circuit of the storage capacitor with semiconductor devices

Abstract

A method and apparatus for testing spark plugs and ignition coils. An apparatus includes a power supply for supplying power to an ignition coil to generate a spark across a spark plug. A capture circuit captures an energy signal reflected from the ignition coil in response to the spark. A comparator circuit compares the captured energy signal to a predetermined signal. A method includes the steps of supplying power to an ignition coil to generate a spark across a spark plug, capturing an energy signal reflected from the ignition coil in response to the spark and comparing the captured energy signal to a predetermined signal. The predetermined signal represents one of a distinct group of reflected energy signals which indicate various defects in the coil or plug. Preferably, a match between the captured energy signal and the predetermined signal is used to indicate to the user a defective coil or plug.

Claims

1. An apparatus for testing at least one ignition coil and at least one spark plug in a spark-ignition engine where said engine has one of a single ignition coil with a plurality of connected spark plugs and a plurality of ignition coils with a single spark plug per coil, the apparatus comprising:

a power supply for supplying power to each ignition coil to generate a spark across each associated spark plug;

at least one capture circuit for capturing an energy signal reflected from each ignition coil in response to said spark generation, each capture circuit positioned between the power supply and each ignition coil for a particular engine to be tested; and

a comparator circuit for comparing said captured energy signal to a predetermined signal.

2. The apparatus as set forth in claim 1 wherein the ignition coil includes a first winding in electrical communication with said power supply and a second winding in electrical communication with the spark plug and wherein said energy signal is reflected from the first winding of the ignition coil in response to said spark generation.

3. The apparatus as set forth in claim 1 wherein said comparator circuit generates an output in response to a match between said captured energy signal and said predetermined signal.

4. The apparatus as set forth in claim 1 wherein said reflected energy signal is a voltage waveform signal.

5. The apparatus as set forth in claim 1 wherein said capture circuit includes a signal isolation and conditioning circuit and a digital scope circuit.

6. The apparatus as set forth in claim 1 wherein said comparator circuit includes a central processor.

7. The apparatus as set forth in claim 1 wherein the ignition coil includes a first winding in electrical communication with said power supply and a second winding in electrical communication with the spark plug and wherein said reflected energy signal is a voltage waveform signal reflected from the first winding of the ignition coil in response to said spark generation.

8. The apparatus as set forth in claim 1 wherein said predetermined signal represents a reflected energy signal produced by an ignition coil and a spark plug having no defects.

9. The apparatus as set forth in claim 1 wherein said predetermined signal represents a reflected energy signal produced by one of a defective ignition coil and a defective spark plug.

10. The apparatus as set forth in claim 1 wherein the spark plug includes an insulator and wherein said predetermined signal represents a reflected energy signal produced by a spark plug having a cracked insulator.

11. The apparatus as set forth in claim 1 wherein the spark plug includes a pair of spaced electrodes and wherein said predetermined signal represents a reflected energy signal produced by a spark plug having an electrode spacing approximately equal to or less than 0.050 inches.

12. The apparatus as set forth in claim 1 wherein the spark plug includes a pair of spaced electrodes and wherein said predetermined signal represents a reflected energy signal produced by a spark plug having an electrically shorted pair of electrodes.

13. The apparatus as set forth in claim 1 wherein said predetermined signal represents a reflected energy signal produced by an electrically open spark plug.

14. The apparatus as set forth in claim 1 wherein the predetermined signal represents a reflected energy signal produced by an electrically open ignition coil.

15. An apparatus for testing an ignition coil connected to a spark plug, comprising:

a power supply for supplying power to the ignition coil to generate a spark across the spark plug;

a capture circuit for capturing an energy signal reflected from the ignition coil in response to said spark generation; and

a comparator circuit for comparing said captured energy signal to a predetermined signal, wherein an output of the comparator circuit identifies one of a spark plug having a cracked insulator, a spark plug having an electrode spacing approximately equal to or less than 0.050 inches, a spark plug having an electrically shorted pair of electrodes, an electrically open spark plug, and an electrically open ignition coil.

16. An apparatus for testing an ignition coil connected to a spark plug wherein the ignition coil and the spark plug are installed in an engine having a separate ignition coil and spark plug for each engine cylinder, the apparatus comprising:

a power supply for supplying power to the ignition coil to generate a spark across the spark plug;

a capture circuit for capturing an energy signal reflected from the ignition coil in response to said spark generation; and

a comparator circuit for comparing said captured energy signal to a predetermined signal; and

wherein the engine includes a plurality of cylinders each having a separate coil and spark plug and wherein said power supply includes an ignition system circuit for supplying power to each ignition coil in a predetermined cycle and wherein a separate supply voltage wire is routed between said power supply and each ignition coil and wherein said predetermined signal represents a reflected energy signal produced by an ignition coil connected to a power supply with a misrouted supply voltage wire.

17. An apparatus for testing an ignition coil connected to a spark plug wherein an insulation boot assembly including a contact spring is connected between the ignition coil and the spark plug, the apparatus comprising:

a power supply for supplying power to the ignition coil to generate a spark across the spark plug;

a capture circuit for capturing an energy signal reflected from the ignition coil in response to said spark generation; and

a comparator circuit for comparing said captured energy signal to a predetermined signal, said predetermined signal representing a reflected energy signal produced by an ignition coil connected to a spark plug with an insulation boot assembly having an electrically open contact spring.

18. An apparatus for testing a set of ignition coils and spark plugs installed in a spark-ignition engine, each ignition coil having first and second windings, the second winding in electrical communication with each associated spark plug, the apparatus comprising:

a power supply connectable to the first winding of each ignition coil for supplying power in a predetermined cycle to the first winding of each ignition coil to generate a spark across each spark plug;

a signal isolation and conditioning circuit for capturing and conditioning each analog voltage waveform signal reflected from only the first winding of each ignition coil in response to each spark generation;

a digital scope circuit for digitizing each of said captured analog voltage waveform signals; and

a central processor for comparing each of said digital signals to a plurality of predetermined signals to detect one of a defective ignition coil and a defective spark plug.

19. A method for testing an ignition coil connected to a spark plug, the ignition coil having first and second windings, the second winding in electrical communication with the spark plug defining a secondary side circuit, the method comprising the steps of:

supplying power to the first winding of ignition coil defining a primary side circuit to generate a spark across the spark plug;

capturing an energy signal reflected from only the first winding of the ignition coil in response to the spark generation; and

comparing the captured energy signal to a predetermined signal to detect a defect in the secondary side circuit.

20. The method as set forth in claim 19 further including the step of generating an output in response to a match between the captured energy signal and the predetermined signal.

21. The method as set forth in claim 19 wherein the step of comparing the captured energy signal to a predetermined signal includes the step of comparing the captured energy signal to a predetermined signal representing a reflected energy signal produced by an ignition coil and a spark plug having no defects.

22. The method as set forth in claim 19 wherein the step of comparing the captured energy signal to a predetermined signal includes the step of comparing the captured energy signal to a predetermined signal representing a reflected energy signal produced by one of a defective ignition coil and a defective spark plug.

23. The method as set forth in claim 19 wherein the spark plug includes an insulator and wherein the step of comparing the captured energy signal to a predetermined signal includes the step of comparing the captured energy signal to a predetermined signal representing a reflected energy signal produced by a spark plug having a cracked insulator.

24. The method as set forth in claim 19 wherein the spark plug includes a pair of spaced electrodes and wherein the step of comparing the captured energy signal to a predetermined signal includes the step of comparing the captured energy signal to a predetermined signal representing a reflected energy signal produced by a spark plug having an electrode spacing approximately equal to or less than 0.050 inches.

25. The method as set forth in claim 19 wherein the spark plug includes a pair of spaced electrodes and wherein the step of comparing the captured energy signal to a predetermined signal includes the step of comparing the captured energy signal to a predetermined signal representing a reflected energy signal produced by a spark plug having an electrically shorted pair of electrodes.

26. The method as set forth in claim 19 wherein the step of comparing the captured energy signal to a predetermined signal includes the step of comparing the captured energy signal to a predetermined signal representing a reflected energy signal produced by an electrically open spark plug.

27. The method as set forth in claim 19 wherein the step of comparing the captured energy signal to a predetermined signal includes the step of comparing the captured energy signal to a predetermined signal representing a reflected energy signal produced by an electrically open ignition coil.

28. A method for testing an ignition coil connected to a spark plug, comprising the steps of:

supplying power to the ignition coil to generate a spark across the spark plug, wherein an insulation boot assembly including a contact spring is connected between the ignition coil and the spark plug;

capturing an energy signal reflected from the ignition coil in response to the spark generation; and

comparing the captured energy signal to a predetermined signal representing a reflected energy signal produced by an ignition coil connected to a spark plug with an insulation boot assembly having an electrically open contact spring.

29. method for testing an ignition coil connected to a spark plug wherein the ignition coil and the spark plug are installed in an engine having a plurality of cylinders, each cylinder having a separate ignition coil and spark plug, comprising the steps of:

supplying power to the ignition coil to generate a spark across the spark plug, wherein a separate supply voltage wire is routed between a power supply and the separate ignition coil of each cylinder;

capturing an energy signal reflected from the ignition coil in response to the spark generation; and

comparing the captured energy signal to a predetermined signal representing a reflected energy signal produced by an ignition coil connected to a power supply with a misrouted supply voltage wire.

30. In an engine assembly line, an apparatus for cold motor testing an engine having at least one ignition coil and at least one spark plug, the improvement comprising:

a power supply for supplying power to the ignition coil to generate a spark across the spark plug;

at least one capture circuit positioned between the power supply and each ignition coil for capturing an energy signal reflected from the ignition coil in response to said spark generation; and

a comparator circuit for comparing said captured energy signal to a predetermined signal.

31. An apparatus for testing an ignition coil connected to a spark plug, the ignition coil having first and second windings, the second winding in electrical communication with the spark plug defining a secondary side circuit, the apparatus comprising:

a power supply connectable to the first winding of the ignition coil defining a primary side circuit for supplying power to the first winding to generate a spark across the spark plug;

a capture circuit for capturing an energy signal reflected from the first winding of the ignition coil in response to said spark generation; and

a comparator circuit for comparing said captured energy signal to a predetermined signal and generating an output in response to a match between said captured energy signal and said predetermined signal indicating a defect in the secondary side circuit.

32. In an apparatus for testing an ignition coil connected to a spark plug, the improvement comprising:

a power supply for supplying power to the ignition coil to generate a spark across the spark plug wherein the ignition coil and the spark are installed in an engine having a separate ignition coil and spark plug for each engine cylinder;

a capture circuit for capturing an energy signal reflected from the ignition coil in response to said spark generation; and

a comparator circuit for comparing said captured energy signal to a predetermined signal.