Integrated engine and exhaust after treatment system and method of operating same

• US 20090288394A1
• Filed: 05/20/2008
• Published: 11/26/2009
• Est. Priority Date: 05/20/2008
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Kesse, Mary L., Jayachandran, Amit, Scrivner, Wade D., Zhu, Liangtao
• Granted Patent: US 8,209,963 B2
• Time in Patent Office: Days
• US Class Current: 60/286
• CPC Class Codes: F01N 13/0093 the purifying devices are of the same type
• CPC Class Codes: F01N 2560/026 for measuring or detecting NOx
• CPC Class Codes: F01N 2610/146 Control thereof, e.g. control of injectors or injection valves
• CPC Class Codes: F01N 2900/0408 using a feed-back loop
• CPC Class Codes: F01N 2900/14 said parameters being related to the exhaust gas
• CPC Class Codes: F01N 3/0821 combined with particulate filters catalysed diesel particulate filters F01N3/035
• CPC Class Codes: F01N 3/208 Control of selective catalytic reduction [SCR], e.g. dosing of reducing agent
• CPC Class Codes: F02D 41/0275 the exhaust gas treating apparatus being a NOx trap or adsorbent
• CPC Class Codes: F02D 41/1446 the characteristics being exhaust temperatures
• CPC Class Codes: F02D 41/266 the computer being backed-up or assisted by another circuit, e.g. analogue
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

An engine system includes an integrated engine and aftertreatment control system via an electronic aftertreatment controller that is in communication with the electronic engine controller. An aftertreatment control algorithm is operable to generate an exhaust control signal and a reductant dosing control signal. The dosing control signal is used to control a flow rate of a reductant (e.g. urea) injection rate into the exhaust system for facilitating a reduction reaction with NOx in the exhaust flow at a suitable downstream catalyst location. The exhaust control signal is communicated to the electronic engine controller, which responds by altering engine operation to change some aspect of the engine exhaust. In one specific example, an ammonia slip event precondition is detected by the electronic aftertreatment controller, and an exhaust control signal in the form of an increase NOx request is communicated to the engine controller, which responds by altering engine operation to increase NOx output in the hopes of preempting the expected ammonia slip event prior to its actual occurrence to maintain undesirable emissions low at the tailpipe.

Claims

1. An engine system comprising:

an electronically controlled engine including a plurality of electrical actuators in communication with an electronic engine controller;

an exhaust aftertreatment system fluidly connected to an exhaust outlet from the electronically controlled engine, and including an electronically controlled reductant delivery system in communication with an electronic aftertreatment controller;

the electronic aftertreatment controller being in communication with the electronic engine controller; and

the electronic engine controller being operable to control the plurality of electrical actuators responsive to an exhaust control signal from the electronic aftertreatment controller.

2. The engine system of claim 1 wherein the exhaust control signal includes a NOx output change request.

3. The engine system of claim 2 wherein the NOx output change request is a NOx output increase request.

4. The engine system of claim 1 wherein the electronic aftertreatment controller includes means for detecting an outgas slip event precondition;

the exhaust control signal is responsive to a detection of the outgas slip event precondition.

5. The engine system of claim 4 wherein the outgas slip event precondition is a reductant slip event precondition;

and

the exhaust control signal includes a NOx output increase request.

6. The engine system of claim 1 wherein the exhaust aftertreatment system includes in series a diesel particulate filter, the electronically controlled reductant delivery system and a NOx reduction catalyst, and further including a temperature sensor adjacent an outlet of the diesel particulate filter, an engine out NOx sensor, and a SCR out NOx sensor.

7. The engine system of claim 6 wherein the electronic aftertreatment controller includes means for detecting an outgas slip event precondition;

the exhaust control signal is responsive to a detection of the outgas slip event precondition;

the means for detecting an outgas slip event precondition includes means for comparing a temperature of engine exhaust upstream from a NOx reduction reaction location in an exhaust system to a predetermined temperature;

means for determining whether a time rate of change of a temperature of engine exhaust upstream from a NOx reduction reaction location has exceeded a predetermined temperature change rate for a predetermined duration;

means for comparing the time rate of change of the determined reductant density to a predetermined density change rate; and

means for determining whether the time rate of change of the determined reductant density is positive and the determined reductant density is greater than a predetermined density.

8. An integrated engine and aftertreatment control system comprising:

an engine control algorithm resident in an electronic engine controller;

an aftertreatment control algorithm resident in an electronic aftertreatment controller;

the electronic aftertreatment controller being in communication with the electronic engine controller;

the aftertreatment control algorithm being operable to generate an exhaust control signal and a reductant dosing control signal; and

the engine control algorithm being operable to generate an engine control signal responsive to the exhaust control signal.

9. The integrated engine and aftertreatment control system of claim 8 wherein the exhaust control signal includes a NOx output change request.

10. The integrated engine and aftertreatment control system of claim 9 wherein the NOx output change request is a NOx output increase request.

11. The integrated engine and aftertreatment control system of claim 8 wherein the aftertreatment control algorithm includes an outgas slip event precondition detection algorithm;

the exhaust control signal is responsive to a detection of an outgas slip event precondition by the outgas slip event precondition detection algorithm.

12. The integrated engine and aftertreatment control system of claim 11 wherein the outgas slip event precondition is a reductant slip event precondition;

and

the exhaust control signal includes a NOx output increase request.

13. The integrated engine and aftertreatment control system of claim 8 wherein the outgas slip event precondition detection algorithm includes a reduction reaction state determination algorithm.

14. The integrated engine and aftertreatment control system of claim 13 wherein the reduction reaction state determination algorithm includes a reduction reaction temperature monitoring algorithm and a catalyst state monitoring algorithm.

15. A method of operating an engine system, comprising the steps of:

supplying exhaust from an engine to an aftertreatment system;

reducing undesirable emissions in the aftertreatment system;

the reducing step including a step of controlling a reductant reaction between NOx and a reductant;

the controlling step including a step of adjusting a reductant delivery system and communicating an exhaust control signal to an electronic engine controller; and

adjusting operation of the engine responsive to the exhaust control signal.

16. The method of claim 15 wherein the step of adjusting operation of the engine includes a step of changing a NOx output from the engine.

17. The method of claim 16 including a step of increasing the NOx output from the engine.

18. The method of claim 15 including a step of detecting an outgas slip event precondition.

19. The method of claim 15 including a step of monitoring a reduction reaction temperature and a density of reductant on a catalyst.

20. The method of claim 19 including a step of determining a time rate of change of the reduction reaction.