METHOD FOR DETERMINING AN AMOUNT OF LIQUID REMOVED FROM A TANK AND REDUCING AGENT SUPPLY DEVICE FOR A MOTOR VEHICLE

• US 20120304626A1
• Filed: 07/13/2012
• Published: 12/06/2012
• Est. Priority Date: 01/13/2010
• Status: Active Grant

• Current Assignee: Continental Emitec GmbH
• Original Assignee: Emitec Gesellschaft für Emissionstechnologie mbH (Continental AG)
• Inventors: MAUS, WOLFGANG, WIERES, LUDWIG, HODGSON, JAN, BRUCK, ROLF
• Granted Patent: US 9,765,668 B2
• Time in Patent Office: Days
• US Class Current: 60/276
• CPC Class Codes: F01N 2610/02 the substance being ammonia or urea
• CPC Class Codes: F01N 2610/1406 Storage means for substances, e.g. tanks or reservoirs
• CPC Class Codes: F01N 2900/1812 Flow rate
• CPC Class Codes: F01N 2900/1814 Tank level
• CPC Class Codes: F01N 3/208 Control of selective catalytic reduction [SCR], e.g. dosing of reducing agent
• CPC Class Codes: G01F 1/708 Measuring the time taken to traverse a fixed distance
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

A method for determining an amount of liquid removed from a tank per unit time includes discontinuously feeding the liquid to exhaust gas of an internal combustion engine by at least feeding the liquid through an injection line into the exhaust gas, measuring pressures simultaneously at least at two points in the injection line and determining an amount of liquid fed in per unit time from the measured pressures. The amount of liquid removed between a first point in time and a second point in time is further derived by integrating the amounts of liquid removed per unit time over a period of time from the first point in time to the second point in time. The method allows the precise consumption of the liquid to be calculated and the remaining amount of liquid in the tank to be additionally determined. On-board diagnosis is further possible with the method.

Claims

1. A method for determining an amount of liquid removed from a tank per unit time, the method comprising the following steps:

discontinuously feeding the liquid removed from the tank through an injection line to exhaust gas of an internal combustion engine;

simultaneously measuring time-dependent pressures at least at two respective points in the injection line; and

determining an amount of the liquid supplied per unit time from the measured pressures.

2. The method according to claim 1, which further comprises establishing an overall amount of liquid removed between a first time and a second time by integrating amounts of liquid removed per unit time over a period of time from the first time to the second time.

3. The method according to claim 2, which further comprises determining an amount of liquid present in the tank at the first time and establishing an amount of liquid present in the tank at the second time by subtracting the established overall amount of liquid removed, from the determined amount of liquid present at the first time.

4. The method according to claim 3, which further comprises virtually continuously establishing the amount of liquid present in the tank after the first time in such a way that a value for the amount of liquid present in the tank is available at all times.

5. The method according to claim 1, which further comprises feeding the liquid in discontinuous injections of less than 100 ms.

6. The method according to claim 5, which further comprises feeding no more than 0.1 ml of the liquid during one injection.

7. The method according to claim 1, which further comprises measuring the pressures only while the liquid is being fed.

8. The method according to claim 1, which further comprises measuring the pressures again at the at least two points during a time interval in which a sound signal does not reach the second point from the first point through the liquid in the injection line.

9. The method according to claim 1, which further comprises determining the amount of liquid fed by solving the non-stationary flow equation for compressible media.

10. The method according to claim 1, which further comprises comparing the amounts of liquid removed per unit time to predeterminable intended amounts and generating a fault signal if deviations between the compared amounts are above predeterminable tolerances.

11. The method according to claim 1, which further comprises comparing the amounts of liquid removed per unit time to predeterminable intended amounts and, if the intended amounts are undershot, feeding liquid once again or increasing a duration of a liquid feed.

12. The method according to claim 10, which further comprises predetermining the intended amounts in dependence on parameters of other components of an exhaust-gas system of the internal combustion engine.

13. The method according to claim 11, which further comprises predetermining the intended amounts in dependence on parameters of other components of an exhaust-gas system of the internal combustion engine.

14. A reducing agent supply device for a motor vehicle having an exhaust-gas line, the supply device comprising:

a tank for a liquid reducing agent;

an injector for injecting the liquid reducing agent into the exhaust-gas line;

an injection line connected between said tank and said injector;

a supply unit configured to deliver the liquid reducing agent from said tank through said injection line to said injector;

at least two pressure sensors for measuring a pressure of the liquid reducing agent; and

a controller connected to said pressure sensors, said injector and said supply unit and configured to carry out the method according to claim 1.

15. The supply device according to claim 14, wherein said injector is attached to the exhaust-gas line of the motor vehicle.