Apparatus, method, and system for diagnosing reductant delivery performance

Patent metadata

Field	Value
Publication number	US-2016010529-A1
Application number	US-201414769614-A
Country	US
Kind code	A1
Filing date	Feb 27, 2014
Priority date	Feb 27, 2013
Publication date	Jan 14, 2016
Grant date	—

Abstract

A system for diagnosing and/or determining the performance of a reductant delivery system may include determining a flow rate offset value for the reductant delivery system. A reduced reductant flow rate may be determined for a reductant dosing command value based, at least in part, on the determined flow rate offset when reductant dosing command is non-zero. A reductant flow rate error can be determined based, at least in part, on a difference between an expected reductant flow rate value corresponding to the reductant dosing command value and the determined reduced reductant flow rate. A performance status value indicative of a performance status of the reductant delivery system may be outputted based, at least in part, on the determined first reductant flow rate error and a predetermined threshold.

First claim

What is claimed is:

1 . A system, comprising:
a reductant delivery system comprising a reductant pump; and a controller configured to:
determine a flow rate offset value for the reductant delivery system, the flow rate offset value based on a first pump command value for the reductant pump when an output pressure value is stabilized and a first reductant dosing command value is zero,
determine a first reduced reductant flow rate for a second reductant dosing command value based, at least in part, on the determined flow rate offset, the second reductant dosing command being non-zero,
determine a first reductant flow rate error based, at least in part, on a difference between a reductant flow rate value corresponding to the second reductant dosing command value and the first determined reduced reductant flow rate, and
output a performance status value indicative of a performance status of the reductant delivery system based, at least in part, on the determined first reductant flow rate error and a predetermined threshold.

2 . The system of claim 1 , wherein the reductant delivery system further comprises a control valve, and wherein the controller is further configured to:
output the first reductant dosing command value to the control valve, and determine an output pressure value is stabilized responsive to an average pressure value remaining within a predetermined range for a desired output pressure for a predetermined period of time.

3 . The system of claim 1 , wherein the flow rate offset value is determined responsive to the second reductant dosing command value being non-zero.

4 . The system of claim 1 , wherein the flow rate offset value is determined responsive to exceeding a maximum learning period.

5 . The system of claim 1 , wherein the controller is further configured to:
determine a second reduced reductant flow rate for the second reductant dosing command value based, at least in part, on the determined flow rate offset, determine a second reductant flow rate error based, at least in part, on a difference between the reductant flow rate value corresponding to the second reductant dosing command value and the second determined reduced reductant flow rate, and determine an accumulated error value based, at least in part, on the first reductant flow rate error and the second reductant flow rate error, wherein the performance status of the reductant delivery system is based on the determined accumulated error value and the predetermined threshold.

6 . The system of claim 5 , wherein the accumulated error value is based on a plurality of reductant flow rate errors over a predetermined error accumulation time threshold.

7 . The system of claim 6 , wherein the accumulated error value is based on a CUSUM analysis of the plurality of reductant flow rate errors.

8 . The system of claim 1 , wherein determining the first reduced reductant flow rate for the reductant dosing command value comprises:
determining a second pump command value for the reductant pump when the output pressure value is stabilized for the second reductant dosing command value, and determining the first reduced reductant flow rate for the second reductant dosing command value based on the determined flow rate offset and the second pump command value.

9 . The system of claim 1 , wherein the performance status value is outputted to an on-board diagnostic (OBD) system.

10 . The system of claim 1 , further comprising:
an internal combustion engine; and an exhaust aftertreatment system in fluid communication with the internal combustion engine for receiving exhaust from the internal combustion engine, wherein the reductant delivery system is in fluid communication with a portion of the exhaust aftertreatment system for dosing a reductant into the exhaust aftertreatment system.

11 . A non-transitory computer-readable medium storing one or more instructions that, when executed by one or more processors, cause the one or more processors to perform operations comprising:
determining a flow rate offset value for a reductant delivery system, the flow rate offset value based on a first pump command value for a reductant pump when an output pressure value is stabilized and a first reductant dosing command value is zero; determining a second pump command value for the reductant pump when the output pressure value is stabilized for a second reductant dosing command value, the second reductant dosing command value being non-zero; determining a first reduced reductant flow rate for the second reductant dosing command value based on the determined flow rate offset and the second pump command value; determining a first reductant flow rate error based, at least in part, on a difference between a reductant flow rate value corresponding to the second reductant dosing command value and the first determined reduced reductant flow rate; and outputting a performance status value indicative of a performance status of the reductant delivery system based, at least in part, on the determined first reductant flow rate error and a predetermined threshold.

12 . The non-transitory computer-readable medium of claim 11 , wherein the stored one or more instructions to cause the one or more processors to perform operations further comprises:
outputting the first reductant dosing command value to a control valve; and determining an output pressure value is stabilized responsive to an average pressure value remains within a predetermined range for a desired output pressure for a predetermined period of time.

13 . The non-transitory computer-readable medium of claim 11 , wherein the stored one or more instructions to cause the one or more processors to perform operations further comprises:
determining a second reduced reductant flow rate for the second reductant dosing command value based, at least in part, on the determined flow rate offset; determining a second reductant flow rate error based, at least in part, on a difference between the reductant flow rate value corresponding to the second reductant dosing command value and the second determined reduced reductant flow rate; and determining an accumulated error value based, at least in part, on the first reductant flow rate error and the second reductant flow rate error; wherein the performance status of the reductant delivery system is based on the determined accumulated error value and the predetermined threshold.

14 . The non-transitory computer-readable medium of claim 13 , wherein the accumulated error value is based on a plurality of reductant flow rate errors over a predetermined error accumulation time threshold.

15 . The non-transitory computer-readable medium of claim 14 , wherein the accumulated error value is based on a CUSUM analysis of the plurality of reductant flow rate errors.

16 . The non-transitory computer-readable medium of claim 11 , wherein the outputted performance status value is a binary value.

17 . A method for determining a performance status of a reductant delivery system comprising a reductant pump, a control valve, and a delivery mechanism, the method comprising:
determining, using one or more data processors, an internal flow rate offset value; determining, using one or more data processors, a reductant flow rate model based on the determined internal flow rate offset value and a slope value, the reductant flow rate model generating an expected reductant flow rate for a normal-operating reductant delivery system responsive to an inputted pump command value; outputting, using one or more dat

Assignees

• Cummins Ip Inc

Inventors

• Wang Kerang
• Mcdaniel Mickey R
• Yuan Yi
• Singh Balbahadur

Classifications

• Y02T10/12

  Improving ICE efficiencies · CPC title

• F01N2610/144

  Control thereof · CPC title

• F01N11/00

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

• F01N3/208 Primary

  Control of selective catalytic reduction [SCR], e.g. by adjusting the dosing of reducing agent · CPC title

• F01N2610/146

  Control thereof, e.g. control of injectors or injection valves · CPC title