Process for checking the operability of an exhaust gas purification catalyst

• US 20010033815A1
• Filed: 03/16/2001
• Published: 10/25/2001
• Est. Priority Date: 03/21/2000
• Status: Active Grant

• Current Assignee: Umicore AG & Company KG (Umicore S.A.)
• Original Assignee: dmc2 Degussa Metals Catalysts Cerdec AG (Vectra Corp.)
• Inventors: Neuhausen, Ulrich, Lox, Egbert, Klein, Harald, Kreuzer, Thomas, Gieshoff, Jurgen
• Granted Patent: US 6,739,176 B2
• Time in Patent Office: Days
• US Class Current: 423/213.2
• 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 11/002 the diagnostic devices measuring or estimating temperature or pressure in, or downstream of the exhaust apparatus
• CPC Class Codes: F01N 11/005 the temperature or pressure being estimated, e.g. by means of a theoretical model
• CPC Class Codes: F01N 2550/02 Catalytic activity of catalytic converters
• CPC Class Codes: F02B 3/06 with compression ignition compression ignition engines using air or gas for blowing fuel into compressed air in cylinder F02B13/02
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A process for checking the operability of an exhaust gas purification catalyst for diesel engines, which has a light-off temperature and a degree of conversion r_CO for carbon monoxide (CO), by direct measurement of the carbon monoxide concentration in combination with a temperature measurement. To evaluate the remaining catalytic activity of the catalyst the difference ΔT between the current catalyst exit temperature T_E of the exhaust gas and the light-off temperature T_CO,50%,fresh of the fresh catalyst for carbon monoxide stored as a function of the speed and load

ΔT=T_E−T_CO,50%,fresh

is determined and the degree of conversion r_CO for carbon monoxide is ascertained.

Claims

1. A process for checking the operability of a catalyst for purification of the exhaust gases of a combustion engine during operation of the engine, wherein the catalyst has a light-off temperature and a degree of conversion r_CO for carbon monoxide (CO), comprising fitting the combustion engine with an electronic control system containing engine electronics and OBD electronics, and evaluating the remaining catalytic activity of the catalyst by determining the difference Δ

T between the current catalyst exit temperature of the exhaust gas T_E and the start-up temperature for carbon monoxide T_CO,50%,fresh of the fresh catalyst at the particular operating point of the engine by the equation;

Δ

T−

T_E−

T_CO,50%,fresh

and evaluating the degree of conversion r_CO for carbon monoxide.

2. The process according to

claim 1

, further comprising determining the degree of conversion r_CO for carbon monoxide by the equation:

3. The process according to

claim 1

, further comprising determining the degree of conversion r_CO for carbon monoxide by the equation:

4. The process according to

claim 2

, further comprising determining a malfunction of the catalyst when the temperature difference Δ

T over a limit value Δ

T_L at an operating point is exceeded with the simultaneous existence of a degree of conversion r_CO for carbon monoxide below a limit value r_CO,L of the degree of conversion for carbon monoxide is recorded in the OBD electronics.

5. The process according to

claim 3

, further comprising determining a malfunction of the catalyst the temperature difference Δ

T over a limit value Δ

T_L at an operating point is exceeded with the simultaneous existence of a degree of conversion r_CO for carbon monoxide below a limit value r_CO,L of the degree of conversion for carbon monoxide is recorded in the OBD electronics.

6. The process according to

claim 4

, farther comprising classifying the catalyst as seriously damaged if the number of operating points for which a malfunction has been found exceeds a preset permitted number n_M of operating points with a malfunction of the catalyst.

7. The process according to

claim 5

, further comprising classifying the catalyst as seriously damaged if the number of operating points for which a malfunction has been found exceeds a preset permitted number n_M of operating points with a malfunction of the catalyst.

8. The process according to

claim 4

, further comprising classifying the catalyst as seriously damaged if the number of operating points for which a malfunction has been found exceeds a preset permitted number n_M of operating points with a malfunction of the catalyst in an interval of time Δ

t_M which is likewise preset.

9. The process according to

claim 5

, further comprising classifying the catalyst as seriously damaged if the number of operating points for which a malfunction has been found exceeds a preset permitted number n_M of operating points with a malfunction of the catalyst in an interval of time Δ

t_M which is likewise preset.

10. The process according to

claim 6

, further comprising signalling to replace the catalyst if the catalyst is classified as seriously damaged.

11. The process according to

claim 7

, further comprising signalling to replace the catalyst if the catalyst is classified as seriously damaged.

12. The process according to

claim 8

, further comprising signalling to replace the catalyst if the catalyst is classified as seriously damaged.

13. The process according to

claim 9

, further comprising signalling to replace the catalyst if the catalyst is classified as seriously damaged comprising.

14. A process for detecting damage to an emissions purification catalyst in a vehicle with a combustion engine, said vehicle having an on board diagnosis electronics system (OBD) with malfunction diagnoses stored therein:

a) setting the first time measurement t and the number n of engine operating points stored with a malfunction of the catalyst at zero,

b) starting time measurement,

c) recording the current engine operating point (OP) from the engine load and speed,

d) testing whether the current operating point (OP) is an element from the amount of operating points (OPs) selected for the evaluation of the catalyst and stored in the OBD electronics,

e) if the testing is negative then recording a new operating point,

f) if the testing is positive, determining if the current operating point OP is a part of the operating points OPm stored thus far for which a malfunction of the catalyst has been found,

g) if a malfunction has been found for the current operating point (OP), recording the current operating point from the engine load and speed,

h) measuring the current exhaust gas temperature downstream of the catalyst,

i) testing whether the current exhaust temperature T_E is greater than the sum of the CO light-off temperature of the fresh catalyst T_{CO,50% fresh} and the limit value of the temperature difference Δ

T_1,

j) if the result of the test (i) is negative, recording a new operating point from the engine load and speed,

k) if the result in (i) is positive, measuring the concentration of CO,

l) determining the degree of conversion r_co for CO and determining whether the value is below the degree of conversion limit, r_co,L

m) if the result in (1) is negative, recording a new operating point from the engine load and speed,

n) if the result in (1) is positive, storing the current operating point in the OBD electronics and adding to the number of operating points for which a malfunction of the catalyst has previously been found,

o) testing to determine if the time that has passed since the first time measurement is shorter than the time interval Δ

tm

p) if the time interval has been exceeded, returning to begin storing of the time measurement t and the number n of operating points stored with malfunctions of the catalyst,

q) if the time interval has not been exceeded, testing to termine if the permitted number n of operating points with malfunction has been reached,

r) if this point has not been reached then continuing with the recordation of operating points,

s) if the point has been reached, storing this number as serious damage to the catalyst in the OBD electronics and signalling a malfunction.