Process for monitoring inductive loads for faults on the control line using sampling techniques

• US 5,384,539 A
• Filed: 01/19/1994
• Issued: 01/24/1995
• Est. Priority Date: 03/30/1990
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Morbe, Matthias, Kornhaas, Robert
• Primary Examiner(s): Wieder, Kenneth A.
• Assistant Examiner(s): Tobin, Christopher M.
• Application Number:
  US08/183,264
• Time in Patent Office: 370 Days
• Field of Search: 324/527, 324/532, 324/535, 324/546, 324/654, 324/656, 123/479, 123/490, 361/154
• US Class Current: 324/527
• CPC Class Codes: B60T 8/36 including a pilot valve responding to an electromagnetic force
• CPC Class Codes: B60T 8/90 using a simulated speed signal to test speed responsive control means
• CPC Class Codes: B60T 8/96 on speed responsive control means
• CPC Class Codes: H01F 7/1844 Monitoring or fail-safe circuits for relays H01H47/002

Abstract

A method for monitoring the operating condition of an inductive load including applying a control pulse to a control line coupled to the inductive load, generating a verification pulse indicating the operating condition of the inductive load, applying the verification pulse to the control line and sampling the verification pulse to determine the operating condition of the inductive load.

Claims

1. A process for monitoring an inductive load for faults, wherein after the end of a drive signal transmitted to the inductive load via a control line, a check is made to determine whether the cut-off peak signal typically associated with a fault-free inductive load occurs, the method comprising the steps of:

applying the drive signal to the control line for driving the inductive load,

generating a verification signal on the control line which depends on the inductive load and the presence of a cut-off peak signal;

sampling the verification signal on the control line at a first predetermined point in time after the end of the drive signal to determine whether the verification signal is present; and

sampling the verification signal on the control line at a second predetermined period of time after the end of the drive signal to determine whether the verification signal is not present.

2. The process according to claim 1, wherein a duration of the verification signal depends on when the amplitude of the cut-off peak signal falls below a predetermined amplitude value.

3. The process according to claim 2, wherein a duration of a verification signal indicating a normal operating condition ends after a third predetermined period of time after the end of the drive pulse.

4. The process according to claim 2, wherein when a short-circuit condition of the inductive load exists, the verification signal generated has a first detection signal waveform indicating a short-circuit condition.

5. The process according to claim 2, wherein when an open-circuit condition of the inductive load exists, the verification signal generated has a second detection signal waveform indicating an open-circuit condition.

6. The process according to claim 2, wherein when an excess temperature condition is detected at a high level stage transistor, the verification signal generated has a third detection signal waveform indicating an excess temperature condition.

7. The process according to claim 2, wherein the inductive load is a solenoid valve, and the control line couples a controller of a control system to the solenoid valve, the process further comprising the step of periodically monitoring the verification signal of the solenoid valve.

8. A method for monitoring an operating condition of an inductive load comprising the steps of:

applying a control pulse having a first predetermined duration to a control line coupled to the inductive load;

comparing an amplitude of an inductive cut-off signal produced by the inductive load to a first predetermined amplitude at the end of the first predetermined duration of the control pulse;

generating a first predetermined time delay when the amplitude of the inductive cut-off is greater than the first predetermined amplitude;

generating a first predetermined waveform if the amplitude of the inductive cut-off signal is greater than the first predetermined amplitude at the end of the first predetermined time delay, the first predetermined waveform having a first arrangement of high and low potential levels indicative of an operating condition of the inductive load;

coupling the first predetermined waveform to the control line;

sampling the control line after a second predetermined period of time after the end of the control pulse to obtain a first sample;

determining whether a high or a low potential level is present on the control line based on the first sample;

sampling the control line after a third predetermined period of time after the end of the control pulse to obtain a second sample, the third predetermined period of time being longer than the second predetermined period of time;

determining whether a high or a low potential level is present on the control line based on the second sample; and

determining the operating condition of the inductive load based on the arrangement of high and low potentials levels determined to be present on the control line for the first and second samples.

9. The method according to claim 8, further comprising the steps of:

sampling the control line after a fourth predetermined period of time after the end of the control pulse to obtain a third sample, the fourth predetermined period of time being shorter than the second predetermined period of time;

determining whether a high or a low potential level is present on the control line based on the third sample; and

determining the operating condition of the inductive load based on the arrangement of high and low potential levels determined to be present on the control line with the first, second and third samples.

10. The method according to claim 8, wherein the step of generating a first predetermined time delay includes the steps of:

generating a second signal when the amplitude of the inductive cut-off is greater than the first predetermined amplitude;

delaying the second signal to produce a third delayed signal; and

generating the first predetermined time delay if the second signal and the third delayed signal coincide.

11. The method according to claim 8, wherein the step of determining whether a high or a low potential level is present on the control line based on the first sample determines that a high potential level is present, and the step of determining whether a high or a low potential level is present on the control line based on the second sample determines that a low potential level is present when the operating condition of the inductive load is a normal operating condition.

12. The method according to claim 8, further comprising the steps of:

generating a second predetermined waveform if the amplitude of the inductive cut-off signal is not greater than the first predetermined amplitude at the end of the first predetermined time delay, the second predetermined waveform having a second arrangement of high and low potential levels indicative of a short-circuit of a coil operating condition of the inductive load;

coupling the second predetermined waveform to the control line;

sampling the control line after the second predetermined period of time after the end of the control pulse to obtain the first sample;

determining whether a high or a low potential level is present on the control line based on the first sample; and

sampling the control line after the third predetermined period of time after the end of the control pulse to obtain the second sample;

determining whether a high or a low potential level is present on the control line based on the second sample; and

determining that a short-circuit of a coil operating condition of the inductive load exists based on the arrangement of high and low potential levels determined to be present on the control line for the first and second samples.

13. The method according to claim 12 wherein the step of determining whether a high or a low potential level is present on the control line based on the first sample determines that a low potential level is present, and the step of determining whether a high or a low potential level is present on the control line based on the second sample determines that a high potential level is present.

14. The method according to claim 9, further comprising the steps of:

generating a third predetermined waveform if an open circuit operating condition of the inductive load exists before the end of the first predetermined time delay, the third predetermined waveform having a third arrangement of high and low potential levels;

coupling the third predetermined waveform to the control line;

sampling the control line after the fourth predetermined period of time after the end of the control pulse to obtain the third sample;

determining whether a high or a low potential level is present on the control line based on the third sample;

sampling the control line after the second predetermined period of time after the end of the control pulse to obtain the first sample;

determining whether a high or a low potential level is present on the control line based on the first sample;

sampling the control line after the third predetermined period of time after the end of the control pulse to obtain the second sample;

determining whether a high or a low potential level is present on the control line based on the second sample; and

determining that an open circuit operating condition of the inductive load exists based on the arrangement of high and low potential levels determined to be present on the control line for the first, second and third samples.

15. The method according to claim 14, wherein the step of determining whether a high or a low potential level is present on the control line based on the third sample determines that a high potential level is present, the step of determining whether a high or a low potential level is present on the control line based on the first sample determines that a high potential signal is present, and the step of determining whether a high or a low potential level is present on the control line based on the second sample determines that a high potential level is present.

16. The method according to claim 9, further comprising the steps of:

generating a fourth predetermined waveform if a temperature rise operating condition of a transistor driving the inductive load exists, the fourth predetermined waveform having a fourth arrangement of high and low potential levels;

coupling the fourth predetermined waveform to the control line;

sampling the control line after the fourth predetermined period of time after the end of the control pulse to obtain the third sample;

determining whether a high or a low potential level is present on the control line based on the third signal;

sampling the control line after the second predetermined period of time after the end of the control pulse to obtain the first sample;

determining whether a high or a low potential level is present on the control line;

sampling the control line after the third predetermined period of time after the end of the control pulse to obtain the second sample;

determining whether a high or a low potential level is present on the control line based on the second sample; and

determining that a temperature rise operating condition of the inductive load exists based on the arrangement of high and low potential levels determined to be present on the control line for the first, second and third samples.

17. The method according to claim 16, wherein the step of determining whether a high or a low potential level is present on the control line based on the third sample determines that high potential level is present, the step of determining whether a high or a low potential level is present on the control line based on the first sample determines that a low potential level is present, and the step of determining whether a high or a low potential level is present on the control line based on the second sample determines that a high potential level is present.

18. The method according to claim 9, further comprising the steps of:

generating a fifth predetermined waveform if a short-circuit operating condition of the inductive load which occurs during application of the control pulse exists, the fifth predetermined waveform having a fifth arrangement of high and low potential levels;

coupling the fifth predetermined waveform to the control line;

sampling the control line after the fourth predetermined period of time after the end of the control pulse to obtain the third sample;

determining whether a high or a low potential level is present on the control line based on the third sample;

sampling the control line after the second predetermined period of time after the end of the control pulse to obtain the first sample;

determining whether a high or a low potential level is present on the control line based on the first sample;

sampling the control line after the third predetermined period of time after the end of the control pulse to obtain the second sample;

determining whether a high or a low potential level is present on the control line based on the second sample; and

determining that a short circuit operating condition of the inductive load occurred during application of the control pulse exists based on the arrangement of high and low potential levels determined to be present on the control line for the first, second and third samples.

19. The method according to claim 18, wherein the step of determining whether a high or a low potential level is present on the control line based on the third sample determines that a low potential level is present, the step of determining whether a high or a low potential level is present on the control line after based on the first sample determines that a high potential level is present, and the step of determining whether a high or a low potential level is present on the control line determines that a high potential level is present.