Monitoring method for an actuator and corresponding driver circuit

• US 20060067024A1
• Filed: 10/31/2003
• Published: 03/30/2006
• Est. Priority Date: 12/03/2002
• Status: Active Grant

• Current Assignee: Continental Automotive GmbH (Continental AG)
• Original Assignee: Siemens AG
• Inventors: Chemisky, Eric, Schrod, Walter
• Granted Patent: US 7,525,783 B2
• Time in Patent Office: Days
• US Class Current: 361/139
• CPC Class Codes: F02D 2400/16 Adaptation of engine control systems to a different battery voltages, e.g. for using high voltage batteries
• CPC Class Codes: F02D 41/2096 for controlling piezoelectric injectors drive and control circuit for piezoelectric devices in general H10N30/802
• 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: F02D 41/221 relating to the failure of actuators or electrically driven elements
• CPC Class Codes: G01R 31/2829 Testing of circuits in sensor or actuator systems testing of apparatus for measuring electric or magnetic variables G01R35/00; testing of indicating or recording apparatus G01D; in airbag systems B60R21/0173; checking gas analysers G01N33/007; monitoring or fail-safe circuits for electromagnets H01F7/1844
• CPC Class Codes: H02N 2/067 generating drive pulses

Abstract

The invention relates to a monitoring method for an actuator (CP), in particular for a piezoelectric actuator (CP) on an injection valve for an internal combustion engine, comprising the following steps: measurement of the electrical current (iR1), flowing through the actuator (CP) in an actuator circuit, measurement of the electrical current (iR3), flowing before or after the actuator (CP) in the actuator circuit, comparison of both measured currents (iR1, iR2) for recognition of a fault and generation of a diagnostic signal (DIAG), displaying the fault, depending on the comparison. According to the invention, the diagnostic signal (DIAG) can take on at least three different values for the representation of an earth short-circuit, a voltage short-circuit and an error-free status depending on the comparison of the measured currents. The invention further relates to a corresponding driver circuit.

Claims

1-20. -20. (canceled)

21. A method of monitoring an actuator connected in an actuator circuit, the method which comprises:

measuring a first electrical current flowing through the actuator;

measuring a second electrical current flowing in the actuator circuit before or after the actuator;

comparing the first and second electrical currents for detection of a fault;

measuring a voltage in the actuator circuit; and

generating a diagnostic signal in dependence on the voltage in the actuator circuit, the diagnostic signal assuming any of at least three mutually different values respectively indicating a ground short circuit, a short circuit to a supply voltage, or an error-free state in dependence on an outcome of the comparing step.

22. The monitoring method according to claim 21, wherein the diagnostic signal is configured to assume at least four mutually different values in dependence on the outcome of comparing the measured first and second currents, to distinguish between a voltage short circuit against to a first voltage and a voltage short circuit to a second voltage.

23. The monitoring method according to claim 21, which comprises measuring a voltage increase and generating the diagnostic signal in dependence on the voltage increase.

24. The monitoring method according to claim 21, which comprises measuring the voltage in the actuator circuit during a charging process, and generating the diagnostic signal in dependence on the measured voltage.

25. The monitoring method according to claim 21, which comprises measuring the voltage in the actuator circuit between a charging process and a discharging process, and generating the diagnostic signal in dependence on the measured voltage.

26. The monitoring method according to claim 21, which comprises measuring the first and second currents flowing in the actuator circuit at two ground-side measuring points.

27. The monitoring method according to claim 21, which comprises measuring the first and second currents flowing in the actuator circuit at two voltage-side measuring points.

28. The monitoring method according to claim 21, which comprises measuring one of the first and second currents at a ground-side measuring point and measuring one of the first and second currents at a voltage-side measuring point.

29. A driver circuit for an actuator, comprising:

an actuator circuit for charging and discharging the actuator, wherein the actuator is connected in said actuator circuit;

a first measuring device for measuring a first electrical current flowing through the actuator;

a second measuring device for measuring a second electrical current flowing in said actuator circuit before or after the actuator;

a third measuring device for measuring an electrical voltage in said actuator circuit during a charging process;

a comparator unit connected to said first, second, and third measuring devices, said comparator unit being configured to effect a comparison between the first and second electrical currents, and to generate a diagnostic signal in dependence on the comparison and in dependence on the electrical voltage measured by said third measuring device, the diagnostic signal taking on one of at least three different values depending on the comparison between the measured currents, in order to distinguish between a ground short circuit, a short circuit to a supply voltage, and an error-free state, respectively.

30. The driver circuit according to claim 29, which further comprises a transformer having a primary winding and a secondary winding, and wherein said secondary winding is connected in said actuator circuit,

31. The driver circuit according to claim 29, wherein said actuator circuit has a first circuit branch and a parallel second circuit branch, said first circuit branch containing a discharge switch and carrying the electrical current during a discharging process, and said second circuit branch containing a diode and carrying the electrical current during a charging process.

32. The driver circuit according to claim 29, wherein said first measuring device comprises a measurement resistor connected in series with the actuator.

33. The driver circuit according to claim 30, wherein said second measuring device comprises a measurement resistor connected in series with a secondary winding of the transformer.

34. The driver circuit according to claim 33, wherein second measurement resistor is connected in the second circuit branch.

35. The driver circuit according to claim 30, wherein said first measuring device comprises a first measurement resistor connected in series with the actuator, and said second measuring device comprises a second measurement resistor connected in series with a secondary winding of the transformer.

36. The driver circuit according to claim 29, wherein said first measuring device and said second measuring device are connected on a ground side of said actuator circuit.

37. The driver circuit according to claim 29, wherein said first measuring device and said second measuring device are connected on a voltage side of said actuator circuit.

38. The driver circuit according to claim 29, wherein one of said first and second measuring devices is connected on a ground side of said actuator circuit and one of said first and second measuring devices is connected on a voltage side thereof.

39. The driver circuit according to claim 29, wherein at least one of said first measuring device and said second measuring device is decoupled from a circuit input.