DE102008034213A1 - Reducing agent- tank i.e. multi-container system, for supplying e.g. aqueous urea solution, to exhaust gas system in vehicle, has measuring device to determine filling conditions of one of containers, before decanting device is enabled - Google Patents

Abstract

The tank (10) has first and second containers (12, 14) for storing reducing agent. A decanting line (28) i.e. is provided for decanting the agent from the second container into the first container. A first filling quantity-measuring device (18) i.e. sensor, is used for determining two different filling conditions of the first container, during emptying the first container and before the decanting device is enabled. A second filling quantity-measuring device (22) is attached to the second container. A third container (16) is provided with a third filling quantity-measuring device (24). The first container is designed as an active container, and the second and third containers are designed as passive containers, and the second and the third filling quantity-measuring devices are designed as one-level-sensors. An independent claim is also included for a method for supplying reducing agent to an exhaust gas system.

Description

The The invention relates to a reductant tank for providing of reducing agent on an exhaust system with a first container for storage of reducing agent, a second container for storing reducing agent and a transfer device for decanting of reducing agent from the second container into the first container. Further The invention relates to a method for providing reducing agent at an exhaust system with the steps: storing reducing agent in a first container, Storing reducing agent in a second container, transferring from Reducing agent from the second container in the first container.

at modern combustion engines, especially with diesel operated by means of a catalytic reduction Proportion of nitrogen oxides in the exhaust gas with a selective catalytic Reaction reduced. The nitrogen oxides are thereby with the help of liquid reagent, for example, an aqueous Urea solution, reduced to nitrogen and water.

To the Saving the liquid Reducing agent are reducing agent tanks used, the as multi-container systems are designed. The reducing agent is in an active tank as the first container and at least one passive tank stored as a second container. To deploy of the reducing agent, this must, inter alia, from the passive tank in diverted the active tank, transferred or be pumped. This is between the passive tank and the active tank a line valve provided. At the passive tank and at the active tank are further level sensors arranged, which for cost reasons designed as so-called 1-level sensors. With them can be determined when the individual tank a minimum level has reached and are filled in accordance with reducing agent in him must, be it as refueling or as refilling from the passive tank in the active tank. The active tank is also a so-called 3-level sensors known, which determines the levels "full", "almost empty" and "empty" can be. The level "full" has it As a result, the driver is told he should refuel break up. The level "almost empty "shows the driver that he must refuel, and the level "empty" leads to a Driving ban, either in the form of a warning or a shutdown of the vehicle.

Around a further control of the levels in the containers too enable, it is also known, the Umfüllmengen to determine mathematically and according to the water levels in the individual containers draw conclusions.

The However, current level sensors have the disadvantage that the Water levels in the passive tank (s) can not be determined accurately enough. One necessary refueling may then not be detected in time become.

Of the Invention is based on the object, a reducing agent tank and to provide a method of providing reducing agent, in which overcome the above-mentioned disadvantages and in particular under all circumstances a sufficient refueling condition of the reducing agent tank can be ensured.

The Task is according to the invention with a reducing agent tank according to claim 1, a reducing agent tank according to claim 5, a method according to claim 6 and a method solved according to claim 10. Advantageous developments are described in the dependent claims.

According to the invention is a Reducing agent tank for providing reducing agent to a Exhaust system provided with a first container for storing reducing agent, a second container for storing reducing agent and a refilling device for refilling Reductant from the second container equipped in the first container is. Furthermore, in the reducing agent tank according to the invention is a the first container assigned filling level measuring device provided by means of at least two different filling states of first container can be determined the while the process of emptying the first container are still going through before the refill (again) becomes active.

With the filling amount measuring device according to the invention at least two degrees of filling can be determined on the first container, resulting from the second container during emptying and before refilling the first container again. These two fill levels form a starting point for an inventively particularly accurate determination of the consumption of reducing agent and can also provide a particularly accurate determination of Umfüllmengen in the first container. In accordance with the invention, the at least two levels can in fact also be used again when transferring into the first container in order to determine the transfer quantities accurately. Thus, according to the invention, both the consumption of reducing agent can be determined more accurately, in order to better determine a correction factor for an associated metering valve and also the functionality of all components used for transfer can be very well checked, because according to the invention, the amounts of refilled reducing agent exactly determined and compared with calculated or control-technical values can be.

at a first advantageous embodiment of the reducing agent tank according to the invention is the capacity meter with a level continuously measuring probe designed. With the probe can open inexpensive Way measured a variety of levels and thus the measurement accuracy can be further increased.

at a second advantageous embodiment of the reducing agent tank according to the invention is a second container associated second filling level measuring device provided by means of only a discrete level of the second container determined can be. With the second level measuring device can in particular determined a predetermined residual amount in the passive tank become. This residual quantity determination provides a hedge of otherwise solely on the active tank taking place quantity determination.

at a third advantageous embodiment of the reducing agent tank according to the invention is a third container provided with a third level measuring device, determined by means of only a discrete level of the third container can be. This particularly simple shape of the third container and its capacity determination is possible, because according to the invention, the filling quantity determination "concentrated" on the first container. In its Considered entirety is the reducing agent tank according to the invention with it usually even cheaper as comparable conventional tanks and at the same time has improved functionalities.

at another solution according to the invention and at the same time the fourth advantageous development of the reducing agent tank according to the invention is one of the first container assigned reducing agent quality measuring device provided which is adapted to the quality of the reducing agent in the first container in the temporal context with a transfer of reducing agent the second container in the first container to investigate. With such a reducing agent quality measuring device can be recognized advantageous, whether reducing agent of inferior quality in the Active tank has been pumped. In this inventive feature is to send in advance that basically in the first container, ie the active tank is filled. Is the active tank during the refueling process quite full, the refueling reductant is almost directly into the passive tank. In such a case, reducing agent becomes less quality (such as pure water) fueled, this just does not get in the active tank, where in conventional Reductant tanks determines the quality of the reducing agent becomes. Used in conventional Reductant tanks so stored in the passive tank "bad" reducing agent transferred to the active tank, This is usually not recognized, because there is a creeping "dilution" of the local Reducing agent results. According to the invention, however, the quality of the reducing agent in active tank in temporal context with a decanting extra considered and it can in this way a "dilution" of reducing agent in the active tank by a decanting of "bad" reducing agent be reliably detected from the passive tank. The temporal context is in particular made so that before and after refilling the quality measured and these values immediately or promptly after transferring each other be compared.

In Corresponding to the abovementioned reducing agent tank is the named Task according to the invention also with a method for providing reducing agent to a Exhaust system solved, which comprises the steps of: storing reducing agent in a first container, Storing reducing agent in a second container, transferring from Reducing agent from the second container in the first container and Measuring at least two different filling conditions of the first container, which when emptying the first container be passed through before being transferred to this from the second container.

Corresponding the above first training is the step of Measuring at least two different Füllzuständen preferred by a continuous Measuring the filling state in the first container.

In Correspondence to the above second training will be in the second container only a single discrete level measured by reducing agent.

When Further development according to the invention Proposed accordingly a method with the following steps: Storing reducing agent in a third container and Measuring only a single discrete level of reducing agent in the third container.

In Corresponding to the above-mentioned further solution and fourth development is according to the invention a method comprising the steps of: storing reducing agent in a first container, Storing reducing agent in a second container, transferring from Reducing agent from the second container in the first container and Measuring the quality of reducing agent in the first container in the temporal context with the decanting of reducing agent from the second container into the first container.

following is an embodiment of solution according to the invention the attached schematic drawing closer explained. It shows:

The Fig. A highly schematic schematic diagram of an embodiment a reducing agent tank according to the invention including exhaust system and combustion engine.

The figure shows a reducing agent tank 10 for providing reducing agent, which as essential components a first container 12 , a second container 14 and a third container 16 includes. The first container 12 is also referred to as "aspirator" or "active container" and serves to store and to provide reducing agent. The second container 14 is also referred to as "pure storage container" or "passive container" and serves only for storing reducing agent. The third container 16 is also referred to as "second passive container".

The first container 12 is a capacity meter 18 assigned, which is designed as a probe. By means of the probe, a plurality of different filling states of the first container 12 be determined. These filling states can during the process of emptying the first container 12 be determined, even before reducing agent from the second container 14 and / or the third container 16 in the first container 12 is transferred.

Furthermore, on the second container 14 a filling level measuring device 22 arranged, which is designed as a 1-level sensor and by means of only a discrete level of the second container 14 can be determined. This can be recognized when only a residual amount of second container 14 located.

At the third container 16 is still a capacity meter 24 arranged, which is also designed as a 1-level sensor for determining a minimum level.

Further, on the first container 12 a reducing agent quality measuring device 26 provided, which is adapted to the quality of the reducing agent in the first container 12 in the temporal context with a transferring of reducing agent from the second container 14 in the first container 12 to investigate. For this purpose, values for the quality of the reducing agent before and after the transfer are stored in a control device and compared with each other. If the quality drifts during or due to transfer, it can be concluded that refilling a low-quality reducing agent. It can then in particular again from the second container 14 to confirm this drift.

Between the containers 12 and 14 is a transfer line 28 arranged in which a pump 30 is arranged. The pump 30 is used to transfer reducing agent from the second container 14 and / or from the third container 16 in the first container 12 operated.

Furthermore, there is a suction line 32 provided, through which with a pump 34 the reducing agent from the first container 12 to a dosing module 36 can be promoted with a designated there, unspecified metering valve. The task of the dosing module 36 lies in the reducing agent in precisely defined amounts in the associated exhaust system 38 inject. It is necessary to monitor the amount actually injected by the metering valve, which is also done with the above-mentioned capacity meter 18 at the first container 12 is possible.

The exhaust system 38 are from a turn associated combustion engine 40 Exhaust gases supplied. The exhaust gas contains nitrogen oxides. These nitrogen oxides are converted to nitrogen and water with the aid of the reducing agent, which in the present case is an aqueous urea solution.

From the intake pipe 32 branches in the flow direction behind the pump 34 a return line 42 from. Here is the pump 34 set up to get out of the container 12 not just the injection in the dosing module 36 required reducing agent sucks, but as a precaution also excess reducing agent. Through the return line 42 such excess reducing agent is returned to the first container 12 recycled. In the return line 42 is an aperture 44 inserted through the return line 42 subsidized amount of reducing agent limited and thereby the dosing 36 prevailing pressure of the reducing agent defined.

10

Reducing agent tank

12

first container

14

second container

16

third container

18

first Capacities measuring device

22

second Capacities measuring device

24

third Capacities measuring device

26

Reductant quality-measuring device

28

Umfüllleitung

30

pump

32

suction

34

pump

36

dosing

38

exhaust system

40

Internal combustion engine

42

Return line

44

cover

Claims (10)

Reducing agent tank ( 10 ) for providing reducing agent to an exhaust system ( 38 ) with a first container ( 12 ) for storing reducing agent, a second container ( 14 ) for storing reducing agent and a refilling device ( 28 ) for transferring reducing agent from the second container ( 14 ) in the first container ( 12 ), in which a first container ( 12 ) associated with filling level measuring device ( 18 ) is provided by means of the at least two different filling states of the first container ( 12 ) can be determined which, when emptying the first container ( 12 ) before the refilling device ( 28 ) becomes active. Reducing agent tank according to claim 1, wherein the filling quantity measuring device ( 18 ) is designed with a level continuously measuring the probe. Reducing agent tank according to claim 1 or 2, wherein a second container ( 14 ) associated second filling quantity measuring device ( 22 ) is provided by means of only a discrete level of the second container ( 14 ) can be determined. Reducing agent tank according to one of claims 1 to 3, in which a third container ( 16 ) with a third filling quantity measuring device ( 24 ) is provided by means of only a discrete level of the third container ( 16 ) can be determined. Reductant tank for providing reducing agent to an exhaust system ( 38 ), in particular according to one of claims 1 to 4, with a first container ( 12 ) for storing reducing agent, a second container ( 14 ) for storing reducing agent and a refilling device ( 28 ) for transferring reducing agent from the second container ( 14 ) in the first container ( 12 ), in which a first container ( 12 ) associated reducing agent quality measuring device ( 26 ), which is adapted to reduce the quality of the reducing agent in the first container ( 12 ) in the temporal context with a transfer of reducing agent from the second container ( 14 ) in the first container ( 12 ) to investigate. Method for providing reducing agent to an exhaust system ( 38 ) comprising the steps of: - storing reducing agent in a first container ( 12 ), Storing reducing agent in a second container ( 14 ), - transfer of reducing agent from the second container ( 14 ) in the first container ( 12 ) and measuring at least two different filling states of the first container ( 12 ), which when emptying the first container ( 12 ) are passed through before, in this from the second container ( 14 ) is transferred. The method of claim 6, wherein the step of measuring at least two different fill states by continuously measuring the fill state in the first container (10). 12 ) he follows. Method according to claim 6 or 7, comprising the step of measuring only a single discrete level of reducing agent in the second container ( 14 ). Method according to one of claims 6 to 8, comprising the steps of: storing reducing agent in a third container ( 16 ) and measuring only a single discrete level of reducing agent in the third container ( 16 ). Method for providing reducing agent to an exhaust system ( 38 ), in particular according to one of claims 6 to 9, with the steps: - storing reducing agent in a first container ( 12 ), - storing reducing agent in a second container ( 14 ), - transfer of reducing agent from the second container ( 14 ) in the first container ( 12 ) and measuring the quality of reducing agent in the first container ( 12 ) in the temporal context with the transfer of reducing agent from the second container ( 14 ) in the first container ( 12 ).