Method and device for monitoring sensor functions

• US 5,617,337 A
• Filed: 10/13/1994
• Issued: 04/01/1997
• Est. Priority Date: 10/20/1993
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Zimmermann, Werner, Ruping, Thomas, Eidler, Franz
• Primary Examiner(s): Voeltz, Emanuel T.
• Assistant Examiner(s): VO, HIEN XUAN
• Application Number:
  US08/322,638
• Time in Patent Office: 901 Days
• Field of Search: 364/424.03, 364/424.04, 364/551.01, 364/431.03, 364/431.05, 364/431.06, 364/431.07, 364/431.11, 73/115, 73/117.3, 73/118.1, 123/479, 123/425, 123/478, 123/198 D, 123/486
• US Class Current: 702/104
• CPC Class Codes: F02D 2250/16 End position calibration, i.e. calculation or measurement of actuator end positions, e.g. for throttle or its driving actuator
• CPC Class Codes: F02D 41/222 relating to the failure of sensors or parameter detection devices
• CPC Class Codes: G01D 18/00 Testing or calibrating apparatus or arrangements provided for in groups G01D1/00 - G01D15/00
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A method and a device for monitoring the functions of a sensor, in particular of a sensor for detecting a measurable value in a motor vehicle. If specified operating states exist, a measurable value is detected and compared to a reference value. Faults are detected when a measured value, held by the sensor, deviates by more than a tolerance value from a reference value. A measured value which had been detected and stored at an earlier instant when a corresponding operating state existed is used as the reference value.

Claims

1. A method for monitoring a sensor comprising the steps of:

(a) detecting a measured value and storing the measured value as a reference value when one of a plurality of specified operating states exists at a first time;

(b) detecting a measurable value when one of the plurality of specified operating states exists at a second time after the detecting and storing in step (a);

(c) comparing the measurable value detected in step (b) with the reference value to determine a magnitude of a difference between the measurable value and the reference value; and

(d) determining a fault when the magnitude of the difference determined in step (c) is greater than a tolerance value, wherein the one of the plurality of operating states includes when a control mechanism is positioned at an end limit stop of the control mechanism.

2. The method of claim 1 wherein the one of the specified operating states is a start-up operation.

3. The method of claim 1 wherein the one of the specified operating states is a coasting operation.

4. The method of claim 1 wherein the one of the specified operating states occurs at regular intervals.

5. The method of claim 1 further comprising the step of:

(e) indicating the fault when the fault is determined in step (d).

6. The method of claim 1 further comprising the step of:

(e) correcting the fault when the fault is determined in step (d).

7. The method of claim 6 wherein the correction of the fault in step (e) includes performing at least one of an additive correction following a sensor characteristic curve and a multiplicative correction following the sensor characteristic curve.

8. The method of claim 1 wherein the reference value is a reference characteristic curve.

9. The method of claim 1 wherein the reference value is a reference characteristic map.

10. A device for monitoring at least one function of a sensor comprising:

a) a reference value storage device for detecting and storing a measured value as a reference value when one of a plurality of specified operating states exists at a first time;

b) a detector for detecting a measurable value when one of the plurality of specified operating states exists at a second time;

c) a comparator, operatively coupled with the detector and with the reference value storage device, for comparing the measured value detected by the detector with the reference value; and

d) a fault detector, operatively coupled with the comparator, for detecting a fault when the measurable value and the reference value differ by more than a tolerance value wherein the one of the plurality of specified operating states includes when a control mechanism is positioned at an end limit stop of the control mechanism.