Method and system for catalyst feedback control

Patent metadata

Field	Value
Publication number	US-10267202-B2
Application number	US-201615285371-A
Country	US
Kind code	B2
Filing date	Oct 4, 2016
Priority date	Oct 4, 2016
Publication date	Apr 23, 2019
Grant date	Apr 23, 2019

Abstract

Methods and systems are provided for catalyst control. In one example, a method may include controlling an air-fuel ratio downstream of a catalyst by adjusting fuel injection. The fuel injection is adjusted based on control parameters updated online through system identification at a point of feedback control instability.

First claim

The invention claimed is:

1. A method for an engine system, comprising:
during steady engine operation, adjusting fuel injection to a cylinder responsive to sensor feedback from downstream of a catalyst volume based on control parameters, the control parameters determined based on system identification at a point of feedback control instability; and
adjusting the fuel injection when variation in engine torque demand is lower than a threshold for a time period.

2. The method of claim 1 , wherein system identification includes identifying system delay and system gain.

3. The method of claim 1 , further comprising adjusting the fuel injection based on an air-fuel ratio upstream of the catalyst volume.

4. The method of claim 1 , further comprising determining the control parameters based on a mass flow upstream of the catalyst volume.

5. The method of claim 1 , further comprising determining the control parameters when a temperature of a second catalyst volume downstream of the catalyst volume is higher than a threshold.

6. The method of claim 1 , further comprising adjusting the fuel injection based on a difference between a filtered reference air-fuel ratio and the sensor feedback, wherein the reference air-fuel ratio is filtered based on the control parameters.

7. A method for an engine system, comprising:
determining a fuel injection amount responsive to an air-fuel ratio downstream of a catalyst via a feedback controller, wherein parameters of the feedback controller are determined via a lookup table based on an exhaust mass flow; and
during steady engine operation, updating the lookup table based on system identification at a point of feedback control instability.

8. The method of claim 7 , further comprising generating the lookup table off-line by driving the system to the point of feedback control instability at each exhaust mass flow.

9. The method of claim 7 , further comprising determining the feedback controller parameters based on an inverse of the system identification.

10. The method of claim 9 , further comprising determining a system delay and a system gain during the system identification.

11. The method of claim 10 , wherein a gain of the feedback controller is increased with decreased system gain.

12. The method of claim 10 , wherein a gain of the feedback controller is increased with decreased system delay.

13. The method of claim 7 , further comprising adjusting fuel injection via an inner feedback loop based on an air-fuel ratio upstream of the catalyst.

14. The method of claim 13 , further comprising driving the system to the point of feedback control instability by controlling the inner feedback loop via a relay function, bypassing the feedback controller.

15. An engine system, comprising:
a cylinder;
fuel injectors for injecting fuel to the cylinder;
a first catalyst;
a second catalyst coupled downstream of the first catalyst;
a first sensor for sensing a first air-fuel ratio upstream of the first catalyst;
a second sensor for sensing a second air-fuel ratio between the first and second catalysts; and
an engine controller configured with computer readable instructions stored in non-transitory memory for:
adjusting a fuel injection amount based on feedback from the first sensor through an inner feedback control loop;
adjusting the fuel injection amount based on feedback from the second sensor through an outer feedback control loop; and
during steady engine operation, updating control parameters of the outer feedback control loop through system identification at a point of feedback control instability.

16. The system of claim 15 , wherein the engine controller is further configured for determining the control parameters of the outer feedback control loop via a lookup table.

17. The system of claim 15 , wherein an oscillation in an air-fuel ratio downstream is induced at the point of feedback control instability.

18. The system of claim 17 , wherein the engine controller is further configured for determining system gain and system delay based on amplitude and a period of the oscillation.

19. The system of claim 15 , wherein the first sensor is a UEGO sensor, and the second sensor is a HEGO sensor.

Assignees

• Ford Global Tech Llc

Inventors

• Magner Stephen William
• Jankovic Mrdjan J
• Santillo Mario Anthony

Classifications

• F01N3/10 Primary

  by thermal or catalytic conversion of noxious components of exhaust · CPC title

• F02D2041/1422

  Variable gain or coefficients · CPC title

• F02D41/18

  by measuring intake air flow · CPC title

• F01N9/00 Primary

  Electrical control of exhaust gas treating apparatus (monitoring or diagnostic devices for exhaust-gas treatment apparatus F01N11/00; conjoint electrical control of two or more combustion engine functions F02D43/00) · CPC title

• F02D41/1441

  Plural sensors · CPC title