# US 2019/0170038 A1 · Method for emptying a reducing agent delivery system belonging to an scr catalytic converter

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- Number: US 2019/0170038 A1
- Document ID: US20190170038A1
- Status: Published application
- Kind: A1
- Application number: 16/308,553
- Filed: 2017-04-12
- Published: 2019-06-06
- Earliest claimed: 2016-06-10
- Assignees: Robert Bosch GmbH
- Applicants: Robert Bosch GmbH
- Inventors: Annabel Hackert; Manuel Simon Reiter; Marc Ringeisen
- Web page: https://patentgrep.com/patent/US20190170038A1

## CPC

- F01N 3/208: {Control of selective catalytic reduction [SCR], e.g. by adjusting the dosing of reducing agent}
- F01N 3/2066: {Selective catalytic reduction [SCR]}
- B01D 53/94: by catalytic processes
- F01N 2550/05: Systems for adding substances into exhaust
- F01N 2610/02: the substance being ammonia or urea
- F01N 2610/1406: Storage means for substances, e.g. tanks or reservoirs
- F01N 2610/144: Control thereof
- F01N 2610/146: Control thereof, e.g. control of injectors or injection valves
- F01N 2610/1473: Overflow or return means for the substances, e.g. conduits or valves for the return path
- Y02T 10/12: Improving ICE efficiencies
- F01N: GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES (arrangements in connection with gas exhaust of propulsion units in vehicles B60K13/00; combustion-air intake silencers specially adapted for, or arranged on, internal-combustion engines F02M35/00; protecting against, or damping, noise in general G10K11/16)
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

The invention relates to a method for emptying a reducing agent delivery system belonging to an SCR catalytic converter, which comprises a delivery line and a return line, each line connecting a reducing agent tank to a delivery module, and which comprises a pressure line that connects the delivery module to a metering valve. The method comprises the following steps: closing (50) the metering valve, and switching the delivery module from a delivering function to a returning function, by switching (51) a switching valve from a first position to a second position. This enables a reducing agent solution to be returned (52) from the return line, the delivery line and the delivery module by means of the delivery module and the delivery line into the reducing agent tank. Subsequently, the metering valve is opened (53) and a reducing agent solution is returned (54) from the metering valve and the pressure line, and also from the return line, via the delivery line into the reducing agent tank. Additionally, the metering valve is closed again (55) in order to empty (56) the return line and the delivery module.

## Claims

### Claim 1

A method for emptying a reducing agent delivery system (1) of an SCR catalytic converter which has a delivery line (41) and a return line (43), which each connect a reducing agent tank (30) to a delivery module (10), and a pressure line (42) which connects the delivery module (10) to a metering valve (22), comprising the following steps:
closing (50) the metering valve (22);
changing over the delivery module (10) from delivery operation to return operation by changing over (51) a changeover valve (12) from a first position to a second position;
returning (52) a reducing agent solution from the return line (43) through the delivery module (10) and the delivery line (41) into the reducing agent tank (30);
opening (53) the metering valve (22);
returning (54) a reducing agent solution from the metering valve (22) and the pressure line (42) through the delivery line (41) into the reducing agent tank (30);
closing (55) the metering valve;
emptying (56) the return line and the delivery module via the delivery line (41) into the reducing agent tank (30); and
carrying out pressure equalization (57) via the return line (43) from the reducing agent tank (30).

### Claim 2 (depends on 1)

The method as claimed in claim 1, characterized in that, after the changeover (51), a pump (14) in the delivery module (10) is operated with a first output until a pressure (p) in the pressure line (42) falls below a first pressure threshold value (p1), and the pump (14) is then operated with a second output, which is greater than the first output.

### Claim 3 (depends on 1)

The method as claimed in claim 1, characterized in that the opening (53) of the metering valve (22) is carried out when a pressure (p) in the pressure line (42) falls below a second pressure threshold value (p2).

### Claim 4 (depends on 1)

The method as claimed in claim 1, characterized in that the opened metering valve (22) is closed (55) after a predefinable first time period (t1) has elapsed.

### Claim 5 (depends on 4)

The method as claimed in claim 4, characterized in that, following the closure (55) of the metering valve (22), the pump (14) is switched off (56) after a predefinable second time period (t2) has elapsed.

### Claim 6 (depends on 5)

The method as claimed in claim 5, characterized in that, after the pump (14) has been switched off (56), the changeover valve (12) is switched (58) into the first position again after a predefinable third time period (t3) has elapsed.

### Claim 7 (depends on 1)

A computer program which is configured to carry out each step of the method as claimed in claim 1.

### Claim 8 (depends on 7)

A non-transitory machine-readable storage medium, on which a computer program as claimed in claim 7 is stored.

### Claim 9 (depends on 1)

An electronic controller (32) which is configured to empty a reducing agent delivery system (1) of an SCR catalytic converter by a method as claimed in claim 1.