Automotive on-board monitoring system for catalytic converter evaluation

• US 5,941,918 A
• Filed: 07/30/1997
• Issued: 08/24/1999
• Est. Priority Date: 07/30/1997
• Status: Expired due to Fees

• Current Assignee: Engelhard Corporation (BASF SE)
• Original Assignee: Engelhard Corporation (BASF SE)
• Inventors: Blosser, Patrick Wayne
• Primary Examiner(s): LOUIS JACQUES, JACQUES H
• Application Number:
  US08/903,524
• Time in Patent Office: 755 Days
• Field of Search: 701/29, 701/34, 701/101, 701/102, 701/103, 701/108, 701/109, 60/274, 60/276, 60/277, 60/285, 73/118.1, 73/23.2, 73/23.31, 73/118.2, 340/439, 340/633, 123/672, 123/688, 123/691, 123/198 D, 364/150, 364/151, 364/528.09, 706/21, 706/10
• US Class Current: 701/29
• 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 13/008 Mounting or arrangement of exhaust sensors in or on exhaust apparatus sensor arrangements for engine control F02D41/1439
• CPC Class Codes: F01N 13/082 of tailpipe, e.g. with means for mixing air with exhaust for exhaust cooling, dilution or evacuation F01N13/20 takes precedence
• CPC Class Codes: F01N 2550/02 Catalytic activity of catalytic converters
• CPC Class Codes: F01N 2560/023 for measuring or detecting HC
• 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

This invention pertains to a vehicular on-board diagnostic emission system in which the system determines whether the vehicle is continuously in compliance with regulatory emission standards by sensing only hydrocarbon and carbon monoxide emissions at a position downstream from the three way catalytic converter. All emission data sensed is correlated to a basic vehicle function, such as speed, and sorted into a number of histograms corresponding to vehicle operating conditions specified by emission regulations. The histograms are sampled in a statistically validated manner to determine if the vehicle complies with emission standards. If a failure has occurred, further histogram diagnostic routines are sequentially implemented to determine which emission system of the vehicle has failed.

Claims

1. An on-board vehicular catalytic converter monitoring system for determining failure of a vehicle to meet emission regulatory standards comprising:

a) an emission sensor downstream of the catalytic converter generating emission signals during vehicle operation indicative of the gaseous pollutants produced by said vehicle'"'"'s internal combustion engine;

b) at least one operative sensor on the vehicle generating operating signals indicative of an operating condition experienced by said vehicle during its operation; and

c) computer means with memory for simultaneously processing said emission signals and said operating signals to determine when and if said emission signals have exceeded regulatory standards, said computer means including;

i) matching means for matching each emission signal with an operating signal;

ii) storing means for storing each emission signal in memory to build a plurality of histograms of emission signals, each histogram correlated to a range of values of an operating condition sensed by said operative sensor such that any given emission signal is stored in a given histogram corresponding to the range of values of said operating signal matched to said given emission signal;

iii) sampling means activated when a set number of emission signals have been stored in said histograms for factoring said emission signals in each histogram to determine a factored emission state of said vehicle at given vehicle operating conditions indicative of the actual pollutants emitted by said vehicle;

iv) comparing means for comparing only said factored emission state to a stored threshold emission level corresponding to a regulatory emission standard for a given vehicle operating condition; and

d) fault indicating means in said vehicle activated to alert the vehicle operator of an emission failure when said comparing means has sensed a factored emission state exceeding said threshold level for said operating condition for a preset number of histograms.

2. The system of claim 1 further including a plurality of second operative sensors, each second operative sensor generating operative signals during vehicle operation indicative of an operating condition of the vehicle'"'"'s internal combustion engine producing gaseous pollutants;

said storing means further including means to associate said plurality of second operative signals with a simultaneously generated emission signal; and

sort means effective when said fault indicating means has been activated to match two or more operative signals associated with a common emission system, said storing means effective to build a plurality of histograms from said matched operative signals to determine from said operative signals what component of said vehicle has caused activation of said fault indicating means.

3. The system of claim 2 wherein said emission sensor is a hydrocarbon sensor and said operative sensor signals are indicative of the speed of the vehicle.

4. The system of claim 3 wherein said operative sensor signals are indicative of the engine speed, engine load and the pollutants produced by said vehicle'"'"'s engine upstream of said catalytic converter.

5. The system of claim 2 wherein said sensors generate analog signals, said system further including analog to digital means for digitizing said emission and said operative signals, means to match and bundle any given plurality of operative signals simultaneously generated with a given emission signal to generate a composite signal, said storage means effective to generate a histogram for any given operative signal and to sample said histogram to determine if said given operative signals stored in said histogram exceed a set threshold level.

6. The system of claim 5 further including said fault indicating means effective to identify a failure of a specific vehicular component depending on any given factored operative signal exceeding a set threshold.

7. The system of claim 6 wherein said means to match and bundle said emission signal and said operative signal includes time stamping each bundled signal, filtering means for comparing, on a timed basis, operative signals in said bundles corresponding to vehicle speed and said storing means effective to build a first histogram of bundled signals of generally constant speed signals and a second histogram of bundled signals in which the speed of the vehicle varies over a set range.

8. The system of claim 2 further including means to check said emission sensor when said internal combustion engine is not running to assure its accuracy.

9. The system of claim 1 wherein said emission sensor is a hydrocarbon sensor.

10. The system of claim 9 wherein said hydrocarbon sensor is a pellistor sensor.

11. The system of claim 1 wherein said sampling means factors said emission signals stored in any given histogram by discarding a set percentage of emission signals indicative of the highest and lowest levels of pollutants sensed by said emission sensor and averaging the remainder of said emission signals to produce a factored emission state indicative of the concentration of pollutants produced by the vehicle'"'"'s internal combustion engine.

12. The system of claim 11 wherein said sampling means samples said histograms only when a set number of adjacent channels in each histogram reach a set number of emission signals stored therein.

13. The system of claim 12 wherein said comparing means compares each histogram'"'"'s factored emission state with a stored regulatory threshold value for each histogram and said fault indicating means is activated when said thresholds for a set percentage of said histograms are exceeded.

14. A method for on-board monitoring of the gaseous pollutant emissions produced by a computer controlled internal combustion engine of a vehicle, said method comprising the steps of:

a) producing emission signals only from an emission sensor downstream of the vehicle'"'"'s catalytic converter;

b) producing at least a first vehicle operative condition signal used by said computer to control the operation of said vehicle'"'"'s internal combustion engine;

c) matching and storing simultaneously generated operative condition signals and emission signals in a plurality of histograms under the control of said computer, each histogram corresponding to a range of values sensed by said operative condition sensor and each emission signal stored in a histogram corresponding to a specific range of operative condition signals determined by the value of said operative condition signal sensed when said emission signal was generated;

d) sampling each histogram once a set number of emission signals have been stored therein by factoring said emission signals in each histogram to determine a statistically validated emission level for each range of sensed operative conditions;

e) comparing each validated emission level with a regulatory threshold emission value corresponding to said operative condition range; and

f) activating a fault detecting alarm in the vehicle when a set number of validated emission levels exceed their corresponding threshold emission level.

15. The method of claim 14 further including in step (b) collecting at least a plurality of second operative condition sensor signals and matching each of said second plurality of operative condition sensors with a given emission signal, and further including the step, after said emission signals have been statistically determined in step (e) to exceed the threshold value, of building and sampling histograms of said first and second operative condition matched sensors signals to ascertain which vehicle component caused said sensed emission signals to exceed the regulatory threshold value.

16. The method of claim 15 wherein said first operative condition includes the speed of said vehicle, and each histogram corresponds to a vehicular speed range.

17. The method of claim 15 wherein said second operative conditions include the oxygen content of the exhaust gas upstream of said vehicle'"'"'s catalytic converter and the air/fuel ratio supplied said vehicle as determined by said vehicle'"'"'s computer, said computer generating air/fuel ratios as a result of vehicle sensor signals received by said computer, said storing step (c) further including storing said oxygen content signals of said exhaust gas in additional histograms at set ranges of said air/fuel ratios, the range determined by the matched air/fuel ratio signal generated simultaneously with said oxygen content signal and step (g) further includes factoring said oxygen content signals subsequently compared to a stored operating condition threshold value to determine if said catalytic converter has caused said failure.

18. The method of claim 14 further including the step of digitizing and bundling said emission and said operative condition signals so that a digitized bundled set of signals are stored in memory, and sampling said operating condition signals when a failure detected by said emission signal has occurred to isolate that vehicular component which has caused said emission failure.

19. The method of claim 18 wherein the histograms correlate emissions to vehicular speed ranges;

said method further including the step of filtering said bundled signals on a timed basis to distinguish bundled signals generated under acceleration/deceleration and steady state speed signals and said matching, and storing step including storing emission signals determined in said filtering step to be steady state speed signals in a first set of histograms and emission signals determined in said filtering step to be acceleration/deceleration signals in a second set of histograms.

20. The method of claim 14 wherein the histograms correlate emissions to vehicular speed ranges;

said method further including the step of filtering said bundled signals on a timed basis to distinguish bundled signals generated under acceleration/deceleration and steady state speed signals and said matching, and storing step including storing emission signals determined in said filtering step to be steady state speed signals in a first set of histograms and emission signals determined in said filtering step to be acceleration/deceleration signals in a second set of histograms.

21. An on-board vehicular catalytic converter monitoring system for determining failure of a vehicle to meet emission regulatory standards comprising:

a) a hydrocarbon sensor downstream of the catalytic converter generating emission signals during vehicle operation indicative of the gaseous pollutants produced by said vehicle'"'"'s internal combustion engine;

b) a speed sensor on the vehicle generating operating speed signals indicative of the speed of said vehicle during its operation; and

c) computer means with memory for simultaneously processing said emission signals and said speed signals to determine when and if said emission signals have exceeded regulatory standards, said computer means including;

i) matching means for matching each emission signal with a simultaneously generated speed signal;

ii) storing means for storing each emission signal in memory to build a plurality of histograms of emission signals, each histogram correlated to a range of speed values such that any given emission signal is stored in a given histogram corresponding to a speed range determined by said speed signal simultaneously generated and matched with any given emission signal;

iii) sampling means activated when a set number of emission signals have been stored in said histograms for factoring said emission signals in each histogram to determine a factored emission state of said vehicle at given vehicle speeds indicative of the actual pollutants emitted by said vehicle;

iv) comparing means for comparing only said factored emission state to a stored threshold emission level corresponding to a regulatory emission standard for any given vehicle speed; and

d) fault indicating means in said vehicle activated to alert the vehicle operator of an emission failure when said comparing means has sensed a factored emission state exceeding said threshold level for a preset number of histograms.

22. The system of claim 21 wherein said sensors generate analog signals, said system further including analog to digital means for digitizing said emission and said speed signals, means to match and bundle any given speed signal with a simultaneously generated emission signal to generate a composite signal, said storage means effective to generate a histogram of emission signals for any given speed signal and to sample said histogram to determine if said emission signals stored in any given histogram exceeds a set threshold level.

23. The system of claim 22 wherein said means to match and bundle said emission signal and said speed signal includes time stamping each bundled signal, filtering means for comparing, on a timed basis, speed signals in said bundles to determine if said vehicle'"'"'s speed is constant, accelerating or decelerating and said storing means effective to build a first histogram of bundled signals of generally constant speed signals and a second histogram of bundled signals in which the speed of the vehicle varies over a set range.

24. The system of claim 23 wherein said sampling means factors said emission signals stored in any given histogram by discarding a set percentage of emission signals indicative of the highest and lowest levels of pollutants sensed by said emission sensor and averaging the remainder of said emission signals to produce a factored emission state indicative of the concentration of pollutants produced by the vehicle'"'"'s internal combustion engine.

25. The system of claim 21 wherein said sampling means factors said emission signals stored in any given histogram by discarding a set percentage of emission signals indicative of the highest and lowest levels of pollutants sensed by said emission sensor and averaging the remainder of said emission signals to produce a factored emission state indicative of the concentration of pollutants produced by the vehicle'"'"'s internal combustion engine.

26. The system of claim 21 further including a plurality of second operative sensors, each second operative sensor generating operative signals during vehicle operation indicative of an operating condition of the vehicle'"'"'s internal combustion engine producing gaseous pollutants;

said storing means further including means to associate said plurality of second operative signals with a simultaneously generated emission signal; and

sort means effective when said fault indicating means has been activated to match two or more operative signals associated with a common emission signal, said storing means effective to build a plurality of histograms from said matched operative signals to determine from said operative signals what component of said vehicle has caused activation of said fault indicating means.