Method for monitoring the operation of a sensor

• US 10,109,118 B2
• Filed: 10/04/2013
• Issued: 10/23/2018
• Est. Priority Date: 10/04/2013
• Status: Active Grant

• Current Assignee: Volvo Truck Corporation (Volvo AB)
• Original Assignee: Volvo Truck Corporation (Volvo AB)
• Inventors: Karlsson, Niclas, Svensson, Magnus, Nowaczyk, Slavomir, Byttner, Stefan, Prytz, Rune, Rognvaldsson, Thorsteinn
• Primary Examiner(s): Black, Thomas G
• Assistant Examiner(s): Li, Ce Li
• Application Number:
  US15/026,221
• Publication Number:
  US 20160232723A1
• Time in Patent Office: 1,845 Days
• CPC Class Codes: F01N 11/00 Monitoring or diagnostic devices for exhaust-gas treatment apparatus , e.g. for catalytic activity safety, indicating or supervising devices for internal combustion engines F02B77/08; testing of machines G01M13/00
• CPC Class Codes: F01N 2250/02 filtering and catalytic conversion
• CPC Class Codes: F01N 2550/00 Monitoring or diagnosing the deterioration of exhaust systems
• CPC Class Codes: F01N 2560/026 for measuring or detecting NOx
• CPC Class Codes: F01N 2610/02 the substance being ammonia or urea
• CPC Class Codes: F01N 3/021 by means of filters
• CPC Class Codes: F01N 3/2066 Selective catalytic reduction [SCR]
• CPC Class Codes: F02D 41/1461 of the exhaust gases emitted by the engine
• CPC Class Codes: F02D 41/1477 characterised by the regulation circuit or part of it,(e.g. comparator, PI regulator, output)
• CPC Class Codes: F02D 41/222 relating to the failure of sensors or parameter detection devices
• CPC Class Codes: G01N 33/0037 NOx
• CPC Class Codes: G01N 33/007 Arrangements to check the analyser calibrating gas analysers G01N33/0006
• CPC Class Codes: G05B 23/0235 based on a comparison with predetermined threshold or range, e.g. "classical methods", carried out during normal operation; threshold adaptation or choice; when or how to compare with the threshold
• CPC Class Codes: G07C 5/0808 Diagnosing performance data testing of vehicles G01M17/00; testing of electrical installation on vehicles G01R31/005
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A method for monitoring the operation of a sensor is provided. The method comprises the step of representing the operation of the sensor by: i) storing a plurality of data values, each data value corresponding to the sensor output signal, wherein said step is performed during a time period such that said data values are distributed over a range of possible data values, ii) defining a plurality of discrete intervals within said range of possible data values; and iii) calculating the frequency of the data values within each interval thus forming a sensor representation. The method further comprises the steps of receiving at least one reference sensor representation; and comparing said sensor representation with said at least one reference sensor representation.

Claims

1. A method of monitoring NOx, comprising:

monitoring NOx in an exhaust aftertreatment system of a vehicle with a NOx sensor;

identifying malfunctions in the NOx sensor by monitoring operation of the NOx sensor, comprising the steps of;

representing the operation of the sensor by;

i) storing a plurality of data values, each data value corresponding to a sensor output signal, wherein the step is performed during a time period such that the data values are distributed over a range of possible data values,

ii) defining a plurality of discrete intervals within a range of possible data values; and

iii) calculating a frequency of the data values within each interval thus forming a sensor representation;

receiving at least one reference sensor representation; and

comparing the sensor representation with the at least one reference sensor representation.

2. The method according to claim 1, wherein the step of storing a plurality of data values is performed for a plurality of different operation modes of a system to which the sensor is connected.

3. The method according to claim 1, wherein the reference sensor representation includes a frequency of reference data values within discrete reference intervals, the discrete reference intervals corresponding to the discrete intervals of the sensor representation.

4. The method according to claim 3, wherein the step of comparing the sensor representation with the reference sensor representation further comprises the step of normalizing the representations.

5. The method according;

to claim 1, wherein the step of comparing the sensor representation with the reference sensor representation further comprises;

calculating a function representing the difference between the sensor representation and the reference sensor representation, and

classifying the function according to a predetermined classification scheme.

6. The method according to claim 5, wherein the classification scheme comprises a plurality of reference categories, wherein each reference category is associated with a specific operation of the sensor.

7. The method according to claim 1, wherein the reference categories include one category corresponding to a sensor operating normally, and at least one category corresponding to a sensor operating non-normally.

8. The method according to claim 7, wherein the reference categories further include one category corresponding to a sensor operating normally in a system operating normally, and at least one category corresponding to a sensor operating normally in a system operating non-normally.

9. The method according to claim 8, wherein the system is an exhaust aftertreatment system of a vehicle.

10. The method according to claim 1, wherein the function is a scalar.

11. The method according to claim 1, wherein the method is repeated for a plurality of times resulting in a set of functions, and further comprising the step of evaluating the set of functions for predicting malfunctioning of the sensor.

12. The method according to claim 1, wherein the reference sensor representation is a previous sensor representation for the sensor.

13. The method according to claim 1, wherein the reference sensor representation corresponds to one or several sensor representations for one or more other sensors.

14. A computer comprising program code for performing the steps of claim 1 when the program is run on the computer.

15. A non-transitory computer readable medium carrying a computer program for performing the steps of claim 1 when the program is run on a computer.

16. A sensor system, comprising

a NOx sensor of a vehicle, and

a controller for identifying malfunctions in the NOx sensor by monitoring operation of the sensor, the controller comprising

a first memory storing a representation of the sensor operation, the sensor representation including a plurality of data values being distributed over a range of possible data values, each data value corresponding to a sensor output signal, and wherein the representation holds information relating to a frequency distribution of the data values within a plurality of discrete intervals,

a second memory storing at least one reference sensor representation, and

a comparing unit configured to compare the sensor representation with the at least one reference sensor representation.

17. The sensor system according to claim 16, further comprising a communication unit configured to receive the sensor representation and the reference sensor representation from the first memory and the second memory and to transmit the sensor representation and the reference sensor representation to the comparing unit.

18. The sensor system according to claim 17, wherein the first memory is arranged on board a vehicle, and wherein the second memory and the comparing unit are arranged off board a vehicle.