Method for detecting failure of a relay

• US 20040047097A1
• Filed: 09/11/2002
• Published: 03/11/2004
• Est. Priority Date: 09/11/2002
• Status: Active Grant

• Current Assignee: Visteon Global Technologies Incorporated (Visteon Corporation)
• Original Assignee: Visteon Global Technologies Incorporated (Visteon Corporation)
• Inventors: Thomas Jordan, Paul, Harry Floros, John
• Granted Patent: US 6,909,285 B2
• Time in Patent Office: Days
• US Class Current: 361/92
• CPC Class Codes: G01R 31/3278 of relays, solenoids or reed switches measuring contact resistance G01R27/205; high voltage magnetic switches G01R31/3271, G01R31/333; testing electric windings G01R31/72; monitoring of fail safe circuits H01H47/002
• CPC Class Codes: H01H 47/002 Monitoring or fail-safe circuits

Abstract

A method for detecting failure of a relay operating in a vehicle having an ignition switch, a power supply, a capacitor, and a pre-charge circuit to pre-charge the capacitor with the relay switching power from the power supply to the pre-charged capacitor, the method comprising the steps of: performing a capacitor pre-charge test; and performing a capacitor discharge test. Preferably, the capacitor pre-charge test is performed when the ignition is switched ON and the capacitor discharge test is performed when the ignition is switched OFF.

Claims

1. A method for detecting failure of a relay operating in conjunction with a power supply, a capacitor, and a pre-charge circuit to pre-charge the capacitor with the relay switching power from the power supply to the pre-charged capacitor, the method comprising the steps of:

activating the pre-charge circuit to initiate pre-charging of the capacitor;

deactivating the pre-charge circuit;

closing the relay to provide power from the power supply to the capacitor; and

re-checking the capacitor for an under-voltage condition.

2. The method of claim 1 further including a step of delaying for a predetermined post-charged time period and wherein the step of checking the capacitor for a post-charged under-voltage condition is performed after the predetermined post-charged time period has elapsed.

3. The method of claim 1 further including the steps of:

checking the capacitor for a pre-charge over-voltage condition; and

checking the capacitor for a pre-charge under-voltage condition.

4. The method of claim 3 wherein the step of checking the capacitor for a pre-charge over-voltage condition further includes repetitively checking the capacitor for a pre-charge over-voltage condition for a predetermined pre-charging time period.

5. The method of claim 4 wherein the step of checking the capacitor for a pre-charge under-voltage condition is performed after the predetermined pre-charging time period has elapsed.

6. A method to detect failure of a relay electrically connected to a power supply and a capacitor with the relay switching power from the power supply to the capacitor, the method comprising the steps of:

opening the relay to disconnect the power supply from the capacitor; and

checking the capacitor for a discharged over-voltage condition.

7. The method of claim 6 further including the step of delaying for a predetermined discharge time period and wherein the step of checking the capacitor for a discharged over-voltage condition is performed after the predetermined discharge time period has elapsed.

8. The method of claim 6 further including the step of storing a capacitor discharge failure error in memory when a discharged over-voltage condition is detected.

9. A method for detecting failure of a relay operating in a vehicle having an ignition switch, a power supply, a capacitor, and a pre-charge circuit to pre-charge the capacitor with the relay switching power from the power supply to the pre-charged capacitor, the method comprising the step of:

performing a capacitor discharge test.

10. The method of claim 9 wherein the capacitor discharge test is performed after the ignition switch is OFF.

11. The method of claim 10 further including the step of re-performing the capacitor discharge test after the ignition switch is ON.

12. The method of claim 9 wherein the step of performing a capacitor discharge test includes the steps of:

opening the relay to disconnect the power supply from the capacitor; and

checking the capacitor for a discharged over-voltage condition.

13. The method of claim 12 further including the step of delaying for a predetermined discharge time period and wherein the step of checking the capacitor for a discharged over-voltage condition is performed after the predetermined discharge time period has elapsed.

14. The method of claim 13 further including the step of storing a capacitor discharge failure error in memory when a discharged over-voltage condition is detected.

15. The method of claim 9 further including a step of performing a capacitor pre-charge test.

16. The method of claim 15 wherein the capacitor pre-charge test is performed after the ignition switch is ON.

17. The method of claim 15 wherein the step of performing a capacitor pre-charge test includes the steps of:

activating the pre-charge circuit to initiate pre-charging of the capacitor;

checking the capacitor for a pre-charge over-voltage condition;

checking the capacitor for a pre-charge under-voltage condition;

deactivating the pre-charge circuit;

closing the relay to provide power from the power supply to the capacitor; and

checking the capacitor for a post-charged under-voltage condition.

18. The method of claim 17 further including a step of delaying for a predetermined post-charged time period and wherein the step of checking the capacitor for a post-charged under-voltage condition is performed after the predetermined post-charged time period has elapsed.

19. The method of claim 17 wherein the step of checking the capacitor for a pre-charge over-voltage condition further includes repetitively checking the capacitor for a pre-charge over-voltage condition for a predetermined pre-charging time period.

20. The method of claim 19 wherein the step of checking the capacitor for a pre-charge under-voltage condition is performed after the predetermined pre-charging time period has elapsed.