Injector deposit detection for scr injection system

Patent metadata

Field	Value
Publication number	US-2018163605-A1
Application number	US-201715828883-A
Country	US
Kind code	A1
Filing date	Dec 1, 2017
Priority date	Dec 12, 2016
Publication date	Jun 14, 2018
Grant date	—

Abstract

A method for monitoring an SCR injection system is disclosed. The method includes operating a pump, and measuring a first pressure drop value in the SCR injection system during actuation of a reductant injector. A second pressure drop value in the SCR injection system is measured during a further actuation of the reductant injector. It is determined to perform a deposit mitigation strategy based on the first pressure drop value and the second pressure drop value.

First claim

1 . A method for monitoring an SCR injection system including a pump and a reductant injector, the method including:
operating the pump; measuring a first pressure drop value in the SCR injection system during actuation of the reductant injector; measuring a second pressure drop value in the SCR injection system during a further actuation of the reductant injector; and determining to perform a deposit mitigation strategy based on the first pressure drop value and the second pressure drop value.

2 . The method of claim 1 , wherein the method step of determining to perform a deposit mitigation strategy includes:
calculating a first deviation between the first pressure drop value and the second pressure drop value; and if the first deviation exceeds a predetermined threshold, performing the deposit mitigation strategy for reducing deposits at the outlet of the reductant injector.

3 . The method of claim 1 , wherein
the first pressure drop value and the second pressure drop value are measured during a priming operation of the SCR injection system, in which the SCR injection system is prepared for operation, wherein, particularly, the pump is operated to pump a fluid to the reductant injector.

4 . The method of claim 3 , wherein the first pressure drop value is measured during a first priming operation, and the second pressure drop value is measured during a second priming operation later than the first priming operation.

5 . The method of claim 4 , wherein the first priming operation and the second priming operation are separated by a shutdown and a restart, or a stop-start of the SCR injection system, particularly a shutdown and a restart of the internal combustion engine.

6 . The method of claim 1 , further comprising:
determining that the first pressure drop value is within a preset acceptable pressure range; and/or determining that the second pressure drop value is within a preset acceptable pressure range.

7 . The method of claim 1 , wherein
the first pressure drop value and the second pressure drop value are measured during a purging operation of the SCR injection system, in which the SCR injection system is purged.

8 . The method of claim 7 , wherein the first pressure drop value is measured during a first purging operation, and the second pressure drop value is measured during a second purging operation later than the first purging operation.

9 . The method of claim 8 , wherein the first purging operation and the second purging operation are separated by a shutdown and a restart, or a stop-start of the SCR injection system, particularly a shutdown and a restart of the internal combustion engine.

10 . The method of claim 7 , wherein the pump is operated to pump a fluid from the reductant injector during each purging operation.

11 . The method of claim 7 , further comprising:
measuring a third pressure drop value in the SCR injection system during actuation of the reductant injector during a priming operation of the SCR injection system, for example a first priming operation; measuring a fourth pressure drop value in the SCR injection system during a later actuation of the reductant injector during a priming operation of the SCR injection system, for example a second priming operation later than the first priming operation; determining to perform a deposit mitigation strategy based on the third pressure drop value and the fourth pressure drop value, for example:
calculating a second deviation between the third pressure drop value and the fourth pressure drop value; and
if the second deviation pressure value exceeds a predetermined threshold, performing a deposit mitigation strategy for reducing deposits at the outlet of the reductant injector,
wherein, optionally:
the first priming operation and the second priming operation are separated by a shutdown and a restart of the SCR injection system; and/or
the pump is operated to pump a fluid to the reductant injector during each priming operation.

12 . The method of claim 1 , wherein the step of determining to perform a deposit mitigation strategy for reducing deposits at an outlet of the reductant injector further comprises selecting one deposit mitigation strategy of a plurality of deposit mitigation strategies based on the first pressure drop value and the second pressure drop value.

13 . The method of claim 1 , wherein the deposit mitigation strategy includes at least one of increasing the exhaust gas temperature, increasing an exhaust gas mass flow, pumping a reductant to the reductant injector, and increasing a dosing rate for the SCR injection.

14 . An SCR injection system for an internal combustion engine, comprising
a reductant tank; a reductant injector; a pump fluidly connecting the reductant tank and the reductant injector; a pressure sensor configured to measure a pressure in the SCR injection system; and a control unit configured to perform a method for monitoring the SCR injection system including, the method including:
operating the pump;
measuring a first pressure drop value in the SCR injection system during actuation of the reductant injector;
measuring a second pressure drop value in the SCR injection system during a further actuation of the reductant injector; and
determining to perform a deposit mitigation strategy based on the first pressure drop value and the second pressure drop value.

15 . The SCR injection system of claim 14 , wherein:
the control unit is further configured to store the first pressure drop value, and optionally also the second pressure drop value; and/or the pressure sensor is integrated in the pump.

Assignees

• Perkins Engines Co Ltd

Inventors

• Gharpure Siddharth Subhash
• Smith Stuart
• Mccloskey James K
• Carlill Tom

Classifications

• F01N3/208 Primary

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

• F01N11/002 Primary

  the diagnostic devices measuring or estimating temperature or pressure in, or downstream of the exhaust apparatus · CPC title

• F01N2900/1808

  Pressure · CPC title

• F01N3/2896

  Liquid catalyst carrier · CPC title

• F01N2610/1493

  Purging the reducing agent out of the conduits or nozzle · CPC title