METHOD AND CONTROL DEVICE FOR MONITORING THE FUNCTION OF A PARTICULATE FILTER

• US 20200131972A1
• Filed: 10/25/2019
• Published: 04/30/2020
• Est. Priority Date: 10/31/2018
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Herberger, Patrik
• Granted Patent: US 11,105,289 B2
• Time in Patent Office: Days
• CPC Class Codes: B01D 46/442 by measuring the concentration of particles
• 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 11/007 the diagnostic devices measuring oxygen or air concentration downstream of the exhaust apparatus
• 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 2550/04 Filtering activity of particulate filters
• CPC Class Codes: F01N 2560/025 for measuring or detecting O2, e.g. lambda sensors
• CPC Class Codes: F01N 2560/05 the means being a particulate sensor
• CPC Class Codes: F01N 2900/0402 using adaptive learning
• CPC Class Codes: F01N 2900/0412 using pre-calibrated maps, tables or charts
• CPC Class Codes: F01N 2900/1402 Exhaust gas composition
• CPC Class Codes: F01N 2900/1606 Particle filter loading or soot amount
• CPC Class Codes: F01N 3/021 by means of filters
• CPC Class Codes: F02D 2200/0812 Particle filter loading
• CPC Class Codes: F02D 2200/1002 Output torque
• CPC Class Codes: F02D 2200/101 Engine speed
• CPC Class Codes: F02D 2200/703 Atmospheric pressure
• CPC Class Codes: F02D 41/0072 Estimating, calculating or determining the EGR rate, amount or flow sensors in EGR systems F02M26/45
• CPC Class Codes: F02D 41/0235 in relation with the state of the exhaust gas treating apparatus control of exhaust gas treating apparatus per se F01N
• CPC Class Codes: F02D 41/1454 the characteristics being an oxygen content or concentration or the air-fuel ratio
• CPC Class Codes: F02D 41/1466 the characteristics being a soot concentration or content
• CPC Class Codes: F02D 41/1467 : with determination means using an estimation
• CPC Class Codes: F02M 26/46 : for determining the characteristics of gases, e.g. composition
• CPC Class Codes: Y02T 10/12 : Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 : Engine management systems

Abstract

A method and control device for monitoring the function of a particulate filter in an exhaust gas duct of an internal combustion engine. A soot emission in the exhaust gas duct downstream from the particulate filter is determined with a particle sensor, an expected soot emission after a limit particulate filter at the location of the particle sensor is simulated and a comparison value is ascertained. A good particulate filter is found if the measured soot emission is less than the comparison value of the simulated soot emission. A defective particulate filter is found if the measured soot emission is higher than the comparison value of the simulated soot emission. The simulated soot emission is determined as being a simulated soot particle concentration at the installation site of the particle sensor such that a basic soot concentration in a soot concentration model is corrected at least with an oxygen correction.

Claims

1. A method for monitoring the function of a particulate filter (12) in an exhaust gas duct (10) of an internal combustion engine, the method comprising:

determining with a particle sensor (30) a soot emission in the exhaust gas duct (10) downstream from the particulate filter (12);

simulating an expected soot emission after a limit particulate filter at the location of the particle sensor (30) and;

ascertaining a comparison value;

wherein a good particulate filter is found if the measured soot emission is less than the comparison value of the simulated soot emission and a defective particulate filter is found if the measured soot emission is higher than the comparison value of the simulated soot emission;

wherein the simulated soot emission is determined as being a simulated soot particle concentration at the installation site of the particle sensor (30) in such a way that a basic soot concentration (101) in a soot concentration model (100) is corrected at least with an oxygen correction (103).

2. The method according to claim 1, wherein the determination of the measured soot emission and the expected soot emission is done time-based with the aid of a current and/or voltage characteristic of the particle sensor (30), wherein a predicted time to reach a flow threshold value after a limit Diesel particulate filter at the location of the particle sensor (30) is calculated and wherein a good Diesel particulate filter is found if the measured time to reach a flow threshold value is greater than the predicted time to reach a flow threshold value and a defective Diesel particulate filter is found if the measured time to reach a flow threshold value is less than the predicted time to reach a flow threshold value.

3. The method according to claim 1, whereinsoot concentration data ascertained by the particle sensor (30), is used to set up the simulated soot particle concentration in the soot concentration model (100).

4. The method according to claim 1, wherein the oxygen correction (103) considers an oxygen concentration in the exhaust gas, wherein the oxygen concentration in the exhaust gas is determined in a sensor-based and/or model-based manner.

5. The method according to claim 1, wherein a smoke limit correction (105) is done, wherein the difference between the maximum possible fuel quantity upon reaching the smoke limit and the currently injected fuel quantity is considered as the smoke limit correction factor (105a).

6. The method according to claim 5, wherein the oxygen concentration in the exhaust gas is considered when determining the smoke limit correction factor (105a).

7. The method according to claim 5, wherein the smoke limit correction factor (105a) is multiplied with a further factor, which is dependent on a particular engine operating point.

8. The method according to claim 7, wherein the engine operating point is the rotational speed and the injection quantity or load of the internal combustion engine.

9. The method according to claim 1, wherein an environmental parameter correction (107) is performed, wherein an environmental air pressure and/or an environmental temperature is determined, wherein a further correction factor (107a) is determined in dependence on an engine operating point and at least one characteristic curve for environmental air pressure and/or environmental temperature, and this is used to correct the basic soot concentration (101).

10. The method according to claim 1, wherein a dynamic correction (109) is performed in such a way that a dynamic correction factor (109a) is determined on the basis of a gradient of a fuel injection quantity and an engine torque and this is used to further correct the basic soot concentration (101).

11. The method according to claim 1, wherein an EGR correction (111) is performed in such a way that an EGR correction factor (11a) is ascertained on the basis of the current overall EGR rate and the environmental temperature and this is used to further correct the basic soot concentration (101).

12. The method according to claim 1, wherein a low-pressure EGR correction (113) is performed in such a way that a low-pressure EGR correction factor (113a) is formed in dependence on a low-pressure EGR fraction and this is used to further correct the basic soot concentration (101).

13. The method according to claim 1, wherein an engine operating mode correction (115) is performed in such a way that, depending on a selected operating mode of the internal combustion engine, an engine operating mode correction factor (115a) is ascertained and used to further correct the basic soot concentration (101).

14. The method according to claim 13, wherein the selected operating mode of the internal combustion engine is determined by polling an engine controller.

15. A control device (28) for monitoring the function of a particulate filter in an exhaust gas duct of an internal combustion engine, which is organized to carry out the method according to claim 1.

16. A non-transitory data storage medium having a computer program stored on it which makes a control device (28) carry out a method according to claim 1 when it is executed on the control device (28).