Methods for detecting a dosing error

Patent metadata

Field	Value
Publication number	US-10677130-B2
Application number	US-201715631432-A
Country	US
Kind code	B2
Filing date	Jun 23, 2017
Priority date	Jun 27, 2016
Publication date	Jun 9, 2020
Grant date	Jun 9, 2020

Abstract

A method for detecting a dosing error of a reduction agent in a dosing module of an SCR catalytic converter system. The SCR catalytic converter system comprises the dosing module, which has a dosing valve and a flow valve as well as a delivery module with delivery pump. The SCR catalytic converter system, furthermore, has a return, in which a further flow valve is arranged. Said flow valve changes an effective cross-sectional area of the return. The method herein comprises the following steps: at the beginning, the dosing valve is closed (200). At a first pressure value (p1) in the system the delivery pump is switched off (201) and a measurement (202) of a first pressure rate (βRLdynamic) of the flow valve of the return subsequently takes place. Additional operation of the pump and the dosing valve occurs and a ratio of pressure rates is determined.

First claim

The invention claimed is:

1. A method for detecting a dosing error of a reduction agent in a dosing module ( 130 ), which comprises a dosing valve ( 131 ) and a first flow valve ( 132 ), of a reduction agent delivery system ( 100 ), which comprises the dosing module ( 130 ), a delivery module ( 110 ) with a delivery pump ( 111 ) and a return ( 160 ), in which a second flow valve ( 161 ), which changes an effective cross-sectional area (A eff ) of the return ( 160 ) is arranged, comprising the following steps:
switching off ( 201 ) the delivery pump ( 111 ) at a first pressure value (p 1 ) in the reduction agent delivery system ( 100 ) when the dosing valve ( 131 ) is closed ( 200 );
measuring ( 202 ) a first pressure rate ( β RL dynamic ) of the second flow valve ( 161 ) of the return ( 160 );
switching on ( 203 ) the delivery pump ( 111 );
switching off ( 205 ) the delivery pump ( 111 ) when a pressure (p) in the reduction agent delivery system ( 100 ) has again reached ( 204 ) the first pressure value (p 1 );
opening ( 206 ) the dosing valve ( 131 ) until the pressure (p) has fallen to a second pressure value (p 2 );
measuring ( 207 ) a second pressure rate ( β RL & DV dynamic ) of the second flow valve ( 161 ) of the return ( 160 ) and of the dosing valve ( 131 ) when the dosing valve ( 131 ) is open;
calculating ( 209 ) a ratio (V) of the two pressure rates ( β RL dynamic , β RL & DV dynamic ); and
checking ( 210 ) an actual volumetric flow rate (Q DV ) through the dosing valve ( 131 ) with the help of the ratio (V).

2. The method according to claim 1 , wherein the delivery pump ( 110 ) during both measurements ( 202 , 207 ; 302 , 307 ) is halted ( 201 , 205 ; 301 , 306 ) at the same angle of rotation (ω) when the delivery pump comprises a rotating delivery pump ( 110 ), and the delivery pump ( 110 ) performs a same stroke prior to both measurements ( 202 , 207 ; 302 , 307 ) when the delivery pump comprises a linearly driven delivery pump.

3. The method according to claim 1 , wherein the second flow valve ( 161 ) in the return, which changes an effective cross-sectional area (A eff ) of the return ( 160 ), is an orifice plate ( 161 ).

4. The method according to claim 1 , wherein the second flow valve ( 161 ) in the return ( 160 ), which changes an effective cross-sectional area (A eff ) of the return, is a choke.

5. The method according to claim 1 , wherein the first pressure rate and the second pressure rate are is a mean relative pressure rates ( β ).

6. The method according to claim 1 , wherein the first pressure rate and the second pressure rate are a mean absolute pressure rates.

7. The method according to claim 1 , wherein the delivery pump ( 111 ) is switched off so slowly and the dosing valve ( 131 ) opened so slowly that a pressure surge of the reduction agent is avoided.

8. The method according to claim 1 , wherein an additional dosing quantity during the measurement ( 207 ; 307 ) of the first pressure rate and second pressure rate ( β RL & DV dynamic , β RL & DV static ) is taken into account ( 211 ; 311 ) in a dosing strategy.

9. A non-transitory, machine-readable storage medium storing a set of instructions that, when executed by a computer, are configured to perform the method according to claim 1 .

10. A method for detecting a dosing error of a reduction agent in a dosing module ( 130 ), which comprises a dosing valve ( 131 ) and a first flow valve ( 132 ), of a reduction agent deliver system ( 100 ), which comprises the dosing module ( 130 ), a delivery module ( 110 ) with a delivery pump ( 111 ) and a return ( 160 ), in which a second flow valve ( 161 ), which changes an effective cross-sectional area (A eff ) of the return ( 160 ) is arranged, comprising the following steps:
switching off ( 301 ) the delivery pump ( 111 ) at a first pressure value (p 1 ) in the reduction agent delivery system ( 100 ) when the dosing valve ( 131 ) is closed ( 300 );
measuring ( 302 ) a first pressure rate ( β RL static ) of the second flow valve ( 161 ) of the return ( 160 );
switching on ( 303 ) the delivery pump ( 111 );
opening ( 305 ) the dosing valve ( 131 ) when a pressure (p) in the reduction agent delivery system ( 100 ) has again reached ( 204 ) the first pressure value (p 1 );
switching off ( 306 ) the delivery pump ( 111 );
measuring ( 307 ) a second pressure rate ( β RL & DV static ) of the second flow valve ( 161 ) of the return ( 160 ) and of the dosing valve ( 131 ) when the dosing valve ( 131 ) is open;
calculating ( 309 ) a ratio (V) of the two pressure rates ( β RL static , β RL & DV static ); and
checking ( 310 ) an actual volumetric flow rate (Q DV ) through the dosing valve ( 131 ) with the help of the ratio (V).

11. An electronic control unit ( 150 ) for detect a dosing error of a reduction agent in a dosing module ( 130 ), the dosing module comprising a dosing valve ( 131 ) and a first flow valve ( 132 ), of a reduction agent deliver system ( 100 ), the reduction agent delivery system ( 100 ) further comprising a delivery module ( 110 ) with a delivery pump ( 111 ) and a return ( 160 ) in which a second flow valve ( 161 ), which changes an effective cross-sectional area (A eff ) of the return ( 160 ), is arranged, the electronic control unit ( 150 ) configured to
switch off ( 301 ) the delivery pump ( 111 ) at a first pressure value (p 1 ) in the reduction agent delivery system ( 100 ) when the dosing valve ( 131 ) is closed ( 300 );
measure ( 302 ) a first pressure rate ( β RL static ) of the second flow valve ( 161 ) of the return ( 160 );
switch on ( 303 ) the delivery pump ( 111 );
open ( 305 ) the dosing valve ( 131 ) when a pressure (p) in the reduction agent delivery system ( 100 ) has again reached ( 204 ) the first pressure value (p 1 );
switch off ( 306 ) the delivery pump ( 111 );
measure ( 307 ) a second pressure rate ( β RL & DV static ) of the second flow valve ( 161 ) of the return ( 160 ) and of the dosing valve ( 131 ) when the dosing valve ( 131 ) is open;
calculate ( 309 ) a ratio (V) of the first pressure rate and second pressure rate ( β RL static , β RL & DV static ); and
check ( 310 ) an actual volumetric flow rate (Q DV ) through the dosing valve ( 131 ) with the help of the ratio (V).

Assignees

• Bosch Gmbh Robert

Inventors

• Farr Thomas
• Linsenmaier Claus

Classifications

• F01N2560/07

  the means being an exhaust gas flow rate or velocity meter or sensor, intake flow meters only when exclusively used to determine exhaust gas parameters · CPC title

• F01N11/002 Primary

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

• F01N3/10

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

• Y02T10/47

  Cross-Sectional Technologies · mapped topic

• F01N2900/1822

  Pump parameters · CPC title