Device and method for monitoring at least one energy reserve capacitor in a restraint system

• US 20070030016A1
• Filed: 03/02/2004
• Published: 02/08/2007
• Est. Priority Date: 04/30/2003
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Schumacher, Hartmut, Heilmann, Gernod
• Granted Patent: US 8,988,084 B2
• Time in Patent Office: Days
• US Class Current: 324/678
• CPC Class Codes: B60R 21/0173 Diagnostic or recording means therefor

Abstract

A method and a device are provided for monitoring an energy reserve capacitor, in which monitoring of the internal resistance is provided in addition to monitoring of the capacitance. This is achieved by a time sequence of charging operations and an interruption of those charging operations.

Claims

1-15. -15. (canceled)

16. A device for monitoring at least one energy reserve capacitor in a restraint system, comprising:

a first arrangement configured to monitor a capacitance of the at least one energy reserve capacitor; and

a second arrangement configured to monitor an ohmic internal resistance of the at least one energy reserve capacitor.

17. The device as recited in claim 16, wherein the second arrangement is configured to determine the internal resistance by a time sequence of at least one charging operation and an interruption of the charging operation of the energy reserve capacitor.

18. The device as recited in claim 16, wherein the second arrangement includes a voltage converter, a rectifier and a voltage divider to monitor the internal resistance.

19. The device as recited in claim 18, wherein the voltage converter has a regulator to regulate the output voltage of the voltage converter.

20. The device as recited in claim 18, wherein the rectifier is a peak rectifier.

21. The device as recited in claim 18, wherein the voltage divider is configured as a low-pass filter.

22. The device as recited in claim 19, wherein a series transistor that controls passage of a battery voltage to the energy reserve capacitor is provided in the voltage converter.

23. A method for monitoring at least one energy reserve capacitor in a restraint system, comprising:

monitoring a capacitance of the at least one energy reserve capacitor; and

monitoring an internal resistance of the at least one energy reserve capacitor.

24. The method as recited in claim 23, wherein the monitoring of the internal resistance includes determining the internal resistance by a time sequence of at least one charging operation and an interruption of the charging operation.

25. The method as recited in claim 23, wherein the internal resistance is monitored by, in a first step, charging the energy reserve capacitor to a first voltage value, in a second step interrupting the charging operation for a first period, in a third step charging the energy reserve capacitor again for a second period until a peak value meter is charged to a second voltage value, in a fourth step interrupting the charging operation for a third period with a result that a voltage at the peak rectifier drops to a third voltage value, and in a fifth step determining the internal resistance from the voltage difference between the second voltage and the third voltage value.

26. The method as recited in claim 25, wherein the first voltage value is above a vehicle battery voltage.

27. The method as recited in claim 25, wherein the charging is carried out in a clocked manner.

28. The method as recited in claim 25, wherein the first period is selected in dependence on a time constant of a low-pass filter connected downstream of the energy reserve capacitor and on a voltage reduction of a rectifier connected downstream of the energy reserve capacitor.

29. The method as recited in claim 28, wherein the second period is selected so that the rectifier is increased to the second voltage value.

30. The method as recited in claim 25, wherein the third period is equal to the first period.