Compression ignition engine system with improved regeneration via controlled ash deposits

Patent metadata

Field	Value
Publication number	US-2016123201-A1
Application number	US-201414531404-A
Country	US
Kind code	A1
Filing date	Nov 3, 2014
Priority date	Nov 3, 2014
Publication date	May 5, 2016
Grant date	—

Abstract

An engine system includes an electronically controlled compression ignition engine configured to burn diesel fuel and a high ash oil to produce an exhaust with a temperature and NOx to soot ratio as well as a controlled level of ash deposits on the particulate filter of the system. An aftertreatment system is fluidly connected to the engine and includes a diesel oxidation catalyst, a reductant supply, and a diesel particulate filter coated with a NOx reduction catalyst. The soot load density on the diesel particulate filter can be stabilized by oxidizing soot at about a same rate as the compression ignition engine is supplying soot to the aftertreatment system.

First claim

We claim:

1 . A method of operating an engine system comprising:
burning a high ash oil in a compression ignition engine, during a break-in period, to generate an ash deposit on a diesel particulate filter of an aftertreatment system fluidly connected to the compression ignition engine; burning a diesel fuel and a low ash oil in the compression ignition engine, after the break-in period, to produce exhaust with a temperature and a NOx to soot ratio, wherein a soot load is disposed on at least a portion of the ash deposit; catalyzing a NOx reduction reaction with a NOx reduction catalyst coated on the diesel particulate filter; and stabilizing the soot load on at least the portion of the ash deposit by oxidizing soot at about a same rate as the compression ignition engine is supplying soot to the aftertreatment system.

2 . The method of claim 1 , wherein the break-in period comprises an initial 100 hours of engine operation, an initial 500 hours of engine operation, an engine operation until a first oil change.

3 . The method of claim 1 , further comprising:
catalyzing a reaction in the exhaust to combine nitrogen oxide with oxygen into nitrogen dioxide with a diesel oxidation catalyst of the aftertreatment system upstream from the diesel particulate filter; and supplying a reductant into the exhaust in the aftertreatment system upstream from the diesel particulate filter.

4 . The method of claim 3 , wherein the reductant comprises urea.

5 . The method of claim 1 , wherein at least the portion of the ash deposit is interposed between a portion of the diesel particulate filter and the soot load.

6 . The method of claim 1 , wherein the stabilizing the soot load comprises changing from a first engine operating condition to a second engine operating condition responsive to one or more of a temperature and a NOx to soot ratio of the exhaust at the diesel particulate filter.

7 . The method of claim 6 , wherein the changing from the first engine operating condition to the second engine operating condition comprises changing from a first exhaust temperature to a second exhaust temperature.

8 . The method of claim 7 , wherein the changing from the first exhaust temperature to the second exhaust temperature is performed in a temperature range corresponding to a temperature at the diesel particulate filter between 180 and 400 degrees C.

9 . An engine system comprising:
an electronically controlled compression ignition engine configured to burn diesel fuel to produce an exhaust with a temperature and a NOx to soot ratio, the electronically controlled compression ignition engine further configured to burn a high ash oil to generate an ash deposit; and an aftertreatment system fluidly connected to the engine, the aftertreatment system comprising a diesel oxidation catalyst and a diesel particulate filter having a NOx reduction catalyst coated on the diesel particulate filter, wherein the NOx to soot ratio and the temperature correspond to a stable soot load density on the diesel particulate filter, and wherein the ash deposit is interposed between NOx reduction catalyst coated on the diesel particulate filter and the stable soot load.

10 . The engine of claim 9 , further comprising an electronic controller in control communication with the engine, the electronic controller configured to determine a soot load density at the diesel particulate filter and to adjust engine operation to stabilize the soot load density.

11 . The engine of claim 10 , further comprising a temperature sensor disposed in the aftertreatment system and in communication with the electronic controller, wherein the electronic controller is configured to receive temperature information from the temperature sensor and to adjust engine operation based at least in part on the temperature information.

12 . The engine of claim 10 , further comprising a NOx sensor disposed in the aftertreatment system and in communication with the electronic controller, wherein the electronic controller is configured to receive NOx to soot ratio information relating to exhaust at the diesel particulate filter and to adjust engine operation based at least in part on the NOx to soot ratio information.

13 . The engine of claim 9 , wherein the stable soot load density is less than a predetermined soot load density corresponding to a runaway exothermic soot oxidation reaction in the diesel particulate filter.

14 . The engine of claim 9 , wherein the diesel particulate filter comprises an inlet channel, and wherein the ash deposit is distributed along a length of the inlet channel as a non-plugging layer.

15 . The engine of claim 9 , further comprising a reductant supply in fluid communication with the aftertreatment system, the reductant supply configured to transmit a reductant into the exhaust, upstream from the diesel particulate filter.

16 . The engine of claim 15 , wherein the reductant comprises urea.

17 . A method of operating an engine system comprising:
catalyzing a reaction in exhaust of the engine system to combine nitrogen oxide with oxygen into nitrogen dioxide with a diesel oxidation catalyst of an aftertreatment system including a diesel particulate filter; catalyzing a NOx reduction reaction with a NOx reduction catalyst coated on the diesel particulate filter; forming a layer of ash on at least a portion of the NOx reduction catalyst coated on the diesel particulate filter; and forming a stable soot load on the diesel particulate filter, wherein the layer of ash is interposed between the diesel particulate filter and the stable soot load.

18 . The method of claim 17 , wherein the forming the layer of ash on the diesel particulate filter comprises receiving a product of combustion of an engine oil.

19 . The method of claim 17 , further comprising catalyzing a NOx reduction reaction with a NOx reduction catalyst coated on the diesel particulate filter.

20 . The method of claim 17 , further comprising:
catalyzing a reaction in the exhaust to combine nitrogen oxide with oxygen into nitrogen dioxide with the diesel oxidation catalyst of the aftertreatment system upstream from the diesel particulate filter; and supplying a reductant into the exhaust in the aftertreatment system upstream from the diesel particulate filter.

Assignees

• Caterpillar Inc

Inventors

• Silver Ronald
• Shull Brandon

Classifications

• F01N3/035 Primary

  with catalytic reactors · CPC title

• F01N11/00

  Monitoring or diagnostic devices for exhaust-gas treatment apparatus · CPC title

• F02B79/00

  Running-in of internal-combustion engines (lubrication thereof F01M7/00) · CPC title

• Y02T10/12

  Improving ICE efficiencies · CPC title

• F01N3/106

  Auxiliary oxidation catalysts · CPC title