Device for supplying liquid reducing agent

Abstract

Device (1) for providing liquid reducing agent comprising a reducing agent tank (2) for storing reducing agent with a tank bottom (3) having a separate chamber (4) and with a metering unit (6) for taking reducing agent from the reducing agent tank (2) at a withdrawal point (7) arranged on the separate chamber (4), wherein the metering unit (6) is arranged inside the separate chamber (4) and the separate chamber (4) is not filled with reducing agent.

Description

[0001] The present invention relates to a device, in particular a tank assembly and a dosing system, for providing liquid reducing agent. Such an assembly can provide a reducing agent for the selective catalytic reduction of exhaust gas components in the exhaust gas of an internal combustion engine at a defined or predetermined pressure. The reducing agent provided at a desired pressure can be supplied to an exhaust gas treatment system, for example, via an injector.

[0002] The prevalence of motor vehicles with lean-burn internal combustion engines has increased significantly. Lean-burn internal combustion engines operate with a fuel-to-air ratio in which more air is supplied to the internal combustion engine than is necessary for the combustion of the simultaneously supplied fuel. The fuel-to-air ratio is normally described by the so-called lambda value. Lean fuel-to-air ratios correspond to a lambda value greater than the stoichiometric ratio of 1.0. Such lean-burn internal combustion engines are characterized by fuel consumption advantages. However, this is sometimes accompanied by significantly increased emissions of nitrogen oxide compounds (NO) in the exhaust gas. These nitrogen oxide compounds can only be avoided to a certain extent with the help of internal engine measures.

[0003] For this reason, the selective catalytic reduction process was developed. In selective catalytic reduction (SCR), a reducing agent or a reducing agent precursor is fed into the exhaust gas in an exhaust gas treatment device. Reducing agent precursors are also regularly referred to as reducing agents. Examples of reducing agents used include ammonia or similar. Examples of reducing agent precursors include urea and / or a urea-water solution. One tried-and-tested reducing agent precursor is a 32.5% urea-water solution, which is available under the trade name AdBlue. Such reducing agent precursors are then converted into the actual reducing agent in the exhaust system and / or in an intermediate evaporator unit and / or hydrolysis unit. A urea-water solution is typically converted to ammonia.In a suitable catalytic converter, nitrogen oxide compounds in the exhaust gas can then be converted together with the ammonia into harmless components such as nitrogen, water and carbon dioxide.

[0004] A dedicated storage and / or dosing system is usually provided in the vehicle for the supply of reducing agents. Such a system can be associated with considerable costs. Furthermore, storing liquid reducing agents, and AdBlue in particular, is problematic because it freezes at low temperatures. AdBlue freezes at approximately -11°C. A system for storing such reducing agents must therefore be designed to withstand freezing.

[0005] Furthermore, it should be possible to reliably determine the reducing agent fill level in the tank. This is particularly important because, for passenger vehicle applications, it is often desirable that the reducing agent in the tank does not need to be refilled during regular operation, but rather that the reducing agent tank is filled (only) during regular vehicle inspections. For this reason, it should be possible to empty the reducing agent tank as completely as possible by the dosing unit during operation, so that no residual reducing agent remains in the reducing agent tank that cannot be pumped by the dosing unit.

[0006] DE 10 2008 031 052 A1 discloses a centrifugal pump for pumping a fluid in a system mounted on a vehicle. The centrifugal pump has a rotational axis that is simultaneously fixedly connected to a mechanical pumping element and a magnetic rotor. This rotor has at least one recess through which the fluid drawn in by the mechanical pumping element is forced.

[0007] DE 697 35 952 T2 discloses a vehicle fuel supply device in which a fuel chamber, support cavities, and fuel flow paths are integrally formed by molding in a sub-tank inserted into and secured to the bottom wall opening of the fuel tank. The fuel pump, a fuel filter, and a pressure regulator are housed and supported in the respective support cavities. The fuel chamber is substantially closed against the rapid flow of fuel, except for the vent opening and the fuel inlet opening through which the fuel flows at a predetermined flow rate per unit time. The fuel chamber has a groove in the wall surface of the fuel pump support cavity for receiving and supporting a power supply line.

[0008] JP 2009-243 331 A discloses a fluid supply device capable of maintaining electrical continuity between a pump and a power supply element. For this purpose, a storage chamber is proposed that is impervious to urea water and is arranged in a cover element.

[0009] Based on this, the object of the present invention is to provide a device for providing liquid reducing agent that at least partially solves the problems described with reference to the prior art. In particular, a device for providing liquid reducing agent is to be disclosed that is particularly cost-effective and / or enables precise fill level determination and the most complete possible emptying of the reducing agent tank during operation.

[0010] These objects are achieved with a device according to the features of patent claim 1. Further embodiments of the invention are specified in the dependent claims. It should be noted that the features listed individually in the dependent claims can be combined with one another in any technologically expedient manner and demonstrate further embodiments of the invention. The description, particularly in conjunction with the figures, explains the invention and provides additional exemplary embodiments.

[0011] The device according to the invention for providing liquid reducing agent has a reducing agent tank for storing reducing agent with a tank bottom which has a separate chamber and is provided with a dosing unit for withdrawing reducing agent from the reducing agent tank at a withdrawal point arranged on the separate chamber, wherein the dosing unit is arranged within the separate chamber and the separate chamber is not filled with reducing agent.

[0012] The basic idea of ​​the invention presented here is to provide the dosing unit in a chamber in or on the tank bottom of the reducing agent tank. A "separated" chamber represents, in particular, a partial volume extending from the underbody toward the tank interior that is not filled with reducing agent, for example, a (separate) indentation, bulge, or the like. Part of the wall of the chamber can be formed integrally with the reducing agent tank or with the tank bottom, thus providing, in particular, separation from the reducing agent. Nevertheless, it may also be possible for the chamber to be formed by a separate housing arranged on or in the tank bottom.The removal of the reducing agent from the reducing agent tank should take place at the chamber and in particular particularly close to the tank bottom, because this is where reducing agent is also available at different fill levels in the reducing agent tank, especially at low fill levels. In particular, the device according to the invention does not have a removal pipe which extends from the top of the reducing agent tank to the tank bottom and through which reducing agent is sucked in. The removal of the reducing agent from the reducing agent tank takes place directly near the separated chamber and / or near the dosing unit. With a dosing unit arranged at the tank bottom, the fill level in the reducing agent tank can be determined using a pressure sensor which is provided on the separated chamber or in the dosing unit.

[0013] Avoiding a withdrawal pipe extending to the top of the tank is advantageous because it saves costs. Furthermore, a vacuum is often required to draw reducing agent through such a withdrawal pipe. Building up a vacuum can be problematic for a pump used in a reducing agent dosing system under certain operating conditions. Piston pumps or diaphragm pumps are typically used. The need to build up a vacuum is avoided by the inventive arrangement of the dosing system in a chamber in the tank bottom.

[0014] According to a further development, it is also proposed to provide the dosing unit with a detachable connection to the reducing agent tank. This allows the dosing unit to be replaced independently of the reducing agent tank. As already explained, the dosing unit regularly has components such as pumps, valves, pressure sensors, temperature sensors, and filters, which have a considerably shorter service life than the reducing agent tank. For this reason, it is advantageous if the dosing unit is detachable from the reducing agent tank. Preferably, a corresponding (sealed) valve arrangement is provided at the fluidic connection point between the reducing agent tank and the dosing unit, which prevents the reducing agent from escaping from the reducing agent tank in an uncontrolled manner when the dosing unit is removed. This is particularly advantageous because the dosing unit is mounted at the bottom of the reducing agent tank.Furthermore, the reducing agent tank in a motor vehicle is usually installed in such a way that it cannot be removed from the vehicle without significant assembly effort. In this case, it is advantageous if the dosing unit is located in the bottom of the reducing agent tank so that it is accessible without having to completely remove the reducing agent tank.

[0015] According to a further development of the device according to the invention, the dosing unit has at least one component from the group of the following components: - pump; - filters; - pressure sensor; - temperature sensor and ; - valve.

[0016] The dosing unit preferably includes all components necessary to deliver the reducing agent at a defined pressure, but in any case at least one pump. This may also include additional pumps, valves, pressure sensors, temperature sensors, and / or filters, as well as electronic components, connecting lines, etc.

[0017] According to a further development, the separated chamber can be closed off from the environment by a lid, and the dosing unit is attached to the lid. In this context, the upper side of the separated chamber is particularly preferably connected in one piece to the tank bottom. In particular, the upper side of the separated chamber and the tank bottom are made of a continuous starting material. For example, the upper side of the separated chamber can be embossed into the tank bottom. The upper side of the chamber represents the actual wall of the tank bottom. In the region of the transition from the separated chamber to the remaining tank bottom, a fastening structure can be provided, to which the lid can be attached.The fastening structure for the cover preferably has at least one screw connection or a sealing surface, wherein the cover can be screwed to the screw connection and in particular forms a tight connection for the (liquid) reducing agent with the sealing surface. The fastening structure can be embossed during manufacture of the tank base. It is also possible for the fastening structure to be cast, welded and / or glued on. The dosing unit with its components described above can be completely (pre-)assembled on the cover so that it can be very easily installed and removed from the separate chamber together with the cover. The individual components of the dosing unit are immediately accessible when the cover is removed.

[0018] The requirements for the tightness of the interior of the separated chamber to the outside are less stringent than those for the tightness of the reducing agent tank itself. The sealing of the interior of the chamber to the outside is generally not in direct contact with the liquid reducing agent, but only has to prevent splash water from outside from entering the interior of the chamber. Therefore, a less stringent seal can be provided to seal the separated chamber to the outside than to seal the reducing agent tank to the outside or to the separated chamber.

[0019] Furthermore, it is considered advantageous if the separated chamber can be removed from the tank bottom. Preferably, the separated chamber is completely removable from the tank bottom. In this case, the tank bottom, without the separated chamber, has (only) an opening into which the separated chamber can be inserted as a whole. The opening in the tank bottom should be designed with a screw connection and / or a sealing surface so that the connection between the separated chamber and the rest of the tank bottom is tight. The separated chamber then forms a closed housing for the dosing unit. The removable, separated chamber can additionally have a cover, via which the dosing unit in the separated chamber is accessible. The separated chamber and the cover of the separated chamber can be fixed in the tank bottom with a common screw connection.It is also possible for the lid to close the separated chamber with a separate screw connection. The separated chamber can then be removed from the tank base as a self-contained dosing system with a housing formed by the separated chamber. If the separated chamber is removable from the tank base, the opening in the tank base can be used for cleaning the tank.

[0020] The device according to the invention is also advantageous if the separated chamber can be secured in the tank base with at least one snap closure. A snap closure is understood to mean, in particular, an SAE closure.

[0021] In this embodiment, the chamber can be attached or fixed to the tank base using an SAE closure and / or a snap-in closure. Preferably, the chamber is designed as a pot with the appropriate closure. The matching counterpart to this closure can be molded into the tank base. This ensures a tight connection between the chamber and the tank base, while simultaneously ensuring easy installation of the chamber in the tank base.

[0022] In a further embodiment of the device, the tank bottom is made of plastic and the separated chamber is designed as a pot injected into the tank bottom.

[0023] In a further development of the device, an O-ring is provided for sealing purposes on the pot injected into the tank bottom.

[0024] This injected pot is preferably made of metal. The tank base is preferably made of plastic. The metal walls of the pot or chamber should only be partially covered by the plastic of the tank base, so that the reducing agent stored in the tank is in contact with the metal walls of the pot. If necessary, an O-ring can also be injected to ensure the tight connection between the pot or chamber and the tank base.

[0025] It is also possible that an O-ring is molded onto the bottom of the tank in the area of ​​the pot, to which a lid seals to close the pot.

[0026] According to a further development, the separated chamber has a melting heater extending away from the tank bottom. Such a melting heater preferably extends over the height of the tank, for example up to the tank roof. In the case of sufficiently low temperatures, the liquid reducing agent can freeze. After restarting the system, it is now desired to quickly melt sufficient reducing agent and keep it ready or pump it for dosing. However, when thawed reducing agent is withdrawn near the tank bottom, there is a risk that the heating power will not be sufficient to penetrate directly into the upper region of the tank. Consequently, a type of "ice cave" can form in which a negative pressure can arise as a result of the pumping of already thawed reducing agent.If a melting heater extending from the tank floor is provided in the separated chamber, this melting heater can melt an opening in the closed ice cover, allowing pressure equalization. If the melting heater extends over the entire height of the tank, an opening in an ice cover arranged at any height can be melted. This allows for the safe provision of liquid reducing agent even when ice is present in the reducing agent tank. The melting heater is preferably designed as a rod heater, with one or more (electrically heated) rod heaters extending from the separated chamber to the tank ceiling.

[0027] Furthermore, it is advantageous if the separated chamber, and in particular the upper wall of the separated chamber, has a heater. The upper wall of the separated chamber separates it from the tank interior. A heater arranged here can heat both the tank interior and the separated chamber with the dosing unit. This allows the frozen reducing agent to be thawed in the immediate vicinity of the dosing system, enabling the rapid provision of liquid reducing agent with the dosing system.

[0028] It is also advantageous if the reducing agent tank is made of plastic and has at least one opening provided with a metallic sleeve. Plastic is the preferred material for the reducing agent tank because plastic tanks are particularly lightweight and their production is particularly cost-effective. However, metallic surfaces can be machined much more precisely than is the case with plastic surfaces. The sealing surfaces at openings in the reducing agent tank must generally be particularly flat. Metallic sleeves at the openings enable such particularly flat surfaces in a reducing agent tank made of plastic. The metallic sleeves can be embedded, cast in, or similarly embedded in the plastic material of the reducing agent tank. It is also advantageous if the openings in the reducing agent tank are as small as possible.The larger the sealing surfaces, the more difficult it becomes to ensure tightness at the sealing surfaces. In a device in which the wall of the tank bottom forms the top of the separated chamber, particularly small sealing surfaces can be provided because only the flow channels from the tank interior to the dosing unit are provided as openings in the reducing agent tank. It is preferred that the largest opening in the reducing agent tank has a diameter of a maximum of 50 mm, preferably a maximum of 10 mm, and particularly preferably a maximum of 5 mm. Furthermore, the reducing agent tank can be designed such that only openings with a diameter of less than 10 mm, preferably less than 5 mm, and particularly preferably less than 2 mm are provided in the region of the tank bottom.

[0029] The device is also particularly advantageous if a stone chip protection device is provided below the separated chamber on the device.

[0030] The interior of the separated chamber should be protected from external stone chips by a stone chip guard. This can be achieved by a suitable design of the cover of the separated chamber with a stone chip guard. If necessary, additional stone chip guard can be provided below the cover. The reducing agent tank is usually arranged in the vehicle such that the separated chamber is accessible from the underbody of the vehicle and there is no further cover. Therefore, stone chips can reach directly as far as the cover of the separated chamber and possibly reach the connections and outlets for releasing the reducing agent. Impairment of the connections can be prevented by the stone chip guard proposed here.

[0031] Furthermore, a recessed metallic sleeve at an opening in the reducing agent tank is particularly advantageous when the separated chamber or the dosing unit is made of metal (or with a metallic housing). This ensures that the reducing agent tank in the area of ​​the opening and the separated chamber and / or the dosing unit have a substantially uniform thermal expansion coefficient.

[0032] It is also possible for a flat metallic ring to be embedded in the tank base, to which the separated chamber is attached via a locking ring. Here, too, the separated chamber is preferably metallic. A metallic ring differs from a metallic sleeve in that a sleeve has at least a partially cylindrical shape, while a metallic ring, within the meaning of the present invention, has a substantially flat shape. The metallic ring is preferably a disc having an opening into which the separated chamber can be inserted.

[0033] It is also advantageous if the tank bottom has a main level and the separate chamber is arranged above the main level. A main level is generally understood to mean a flat surface in or directly on which the largest part of the tank bottom is arranged and up to which the tank interior extends at least partially. If the separate chamber is arranged above this main level, the tank bottom has no or only a few partial areas that project downwards beyond this main level, so that the dimensions of the device are essentially determined by the dimensions of the reducing agent tank. The withdrawal point of the dosing unit for the reducing agent should also be arranged close to the main level so that the reducing agent tank can be emptied as completely as possible during operation.

[0034] It is also advantageous if the tank bottom has a main level and the dosing unit has a reducing agent outlet, and the reducing agent outlet terminates at a height of less than 50 mm, preferably less than 40 mm, and particularly preferably less than 30 mm, below the main floor level. A reducing agent line can be connected to the reducing agent outlet, through which the dosing unit delivers the reducing agent to an injector. The injector supplies the reducing agent to an exhaust gas treatment component. The reducing agent outlet of the dosing unit is preferably designed downwards.

[0035] Also shown is a motor vehicle having an internal combustion engine and an exhaust gas treatment system having an injector for reducing agent and a device as described above, wherein the injector is connected to the device via a reducing agent line.

[0036] The invention and the technical environment are explained in more detail below with reference to the figures. The figures show particularly preferred embodiments. They show: Fig. 1: a first embodiment of the device, Fig. 2: a second embodiment of the device, Fig. 3: a third embodiment of the device, Fig. 4: a motor vehicle having a device, Fig. 5 a variant of the device and Fig. 6 another variant of the device.

[0037] In the Fig. 1, Fig. 2 and Fig. 3 shows three different embodiments of a device 1 according to the invention, which have in common components, some of which are provided with the same reference numerals and which will be described here first.

[0038] The devices 1 in the Fig. 1, Fig. 2 and Fig. 3 each have a reducing agent tank 2 with a tank bottom 3 and a tank interior 5 in which the reducing agent (e.g. aqueous urea solution, which is liquid under normal conditions) is stored. In the tank bottom 3, a separate chamber 4 is provided in each case, in which the dosing unit 6 is arranged. The tank bottom 3 in each case has a main bottom plane 15. The dosing unit 6 in each case has a reducing agent outlet 16 which projects downwards above the main bottom plane 15 by a height 17. The main bottom plane 15 here forms a contact surface on which the reducing agent tank 2 rests if corresponding recesses are provided in a support surface in the area of ​​the separate chamber. The height 17 should not exceed 50 mm if possible. The dosing unit 6 in each case has a base plate 35 on which various components 36 are (pre-)mounted.The components 36 can be, for example, valves, filters, pumps, pressure sensors, temperature sensors, or similar components that are useful in the dosing unit 6 for providing liquid reducing agent at a defined pressure at the reducing agent outlet 16. The components 36 can be mounted in the separate chamber on a base plate 35. Furthermore, it is also possible for corresponding mounting points for the individual components 36 to be provided on the walls of the separate chamber 4. This may achieve efficient heat exchange between the tank interior 5 and the components 36 of the dosing unit 6.

[0039] In Fig. 1, a stone chip guard 47 is provided below the separated chamber 4 in the area of ​​the reducing agent outlet 16 on the tank bottom 3. This stone chip guard 47 can effectively protect the reducing agent outlet 16 from stone chipping from below. The stone chip guard 47 can be attached to the separated chamber 4 or to the tank bottom 3. The stone chip guard 47 can also be removable.

[0040] The dosing unit 6 is now in the Fig. 1 and Fig. 3 are each mounted differently in the separate chamber 4.

[0041] In Fig. 1, the various components 36 of the dosing unit 6 of the device 1 according to the invention are described in more detail by way of example. Components 36 include a pump 41, a filter 42, a pressure sensor 43, a temperature sensor 44, and a valve 45.

[0042] Fig. 1 shows that the dosing unit 6 is attached to a cover 8, through which the separated chamber 4 can be closed from below. An upper side of the separated chamber 4 is formed by an insert 40. The cover 8 and insert 40 are fastened in an opening 13 of the reducing agent tank 2 with a screw connection 10. To ensure that the reducing agent tank 2 is fluid-tight, the opening 13 of the reducing agent tank has a sealing surface 11, so that the insert 40 is sealed against the sealing surface 11 by means of O-rings 34. The sealing surface 11 in the reducing agent tank 2 is realized by means of a metallic sleeve 14 embedded in the reducing agent tank 2.

[0043] The connection between a plastic tank and a metallic sleeve or ring is fluid-tight if the metallic sleeve or ring is cast or melted into the plastic of the tank.

[0044] In Fig. 2, the arrangement of the dosing unit 6 in the separated chamber 4 is realized in a similar manner. Here, too, the separated chamber 4 is closed at the bottom by a cover 8. The top of the separated chamber 4 is formed by an insert 40. The dosing unit 6 is fastened to the insert 40. The cover 8 is screwed into the insert 40 at an additional screw connection 10. No sealing surface is provided here. The cover 8 only has to ensure tightness against the ingress of splash water from outside into the separated chamber 4. For the tightness of the tank interior 5 with regard to leakage of reducing agent, the sealing of the cover 8 according to the Fig. 2 is not important. The insert 40 is inserted into an opening 13 of the reducing agent tank 2 by means of a screw connection 10. To seal the insert 40 and the reducing agent tank 2 from each other, a sealing surface 11 is also provided here, the sealing being effected by O-rings 34. As in Fig. 1, a metallic sleeve 14 is embedded in the reducing agent tank 2 in order to be able to realize the sealing surface 11 particularly advantageously.

[0045] Fig. Figure 3 shows a different concept for the design of the separated chamber 4 and the arrangement of the dosing unit 6. The upper wall of the separated chamber 4 is continuous here, designed as a direct and materially bonded component of the tank bottom 3. Such a tank bottom 3 can be manufactured, for example, by a deep-drawing process from a one-piece starting material. The separated chamber 4 forms, so to speak, an indentation of the tank bottom 3 into the tank interior 5. A screw connection 10 and a sealing surface 11 are provided around this indentation. The separated chamber 4 can be closed with a cover 8 at this sealing surface 11 and at this screw connection 10. Here, too, only a seal against the ingress of splash water from outside into the separated chamber 4 must be realized. For sealing the tank interior 5 against leakage of reducing agent, the sealing of the cover 8 according to Fig. 3 is irrelevant. The dosing unit 6 is connected to the cover 8. When the cover 8 is removed from the reducing agent tank 2, the dosing unit 6 with its components 36 is accessible. The only passage in the area of ​​the tank bottom 3 from the tank interior 4 of the reducing agent tank 2 is the opening 13, through which reducing agent from the tank interior 4 enters the dosing unit 6. This opening 13 can be designed with a very small diameter. It is also possible to design this opening 13 of the reducing agent tank 2 with a metal sleeve 14. The diameter of this opening 13 can be very small, so that tightness can be achieved particularly easily here.

[0046] For the design variants according to the Fig. 1 and Fig. 3, a coupling 33 is provided, by which the connection between the tank interior 4 and the dosing unit 6 is established when the dosing unit 6 is inserted into the separated chamber 4. This coupling 33 is preferably also designed with O-rings 34. All three embodiments according to the Fig. 1 to 3 also have tank heaters 9, which are preferably provided on the top side of the separated chamber 4 between the tank interior 5 and the separated chamber 4. As a special feature, Fig. 2 shows a melt heater 30. A melt heater 30 is a tank heater 9 that extends upwards from the tank bottom 3. Preferably, a melt heater 30 extends over (almost) the entire height of the tank interior 5.

[0047] Furthermore, the Fig. 1 to 3 different variants, such as a return line 32 from which the dosing unit 6 can be led back into the tank interior 5. Fig. 1 shows that the return line 32 is routed so that it ends in the upper area of ​​the tank interior 5. Air bubbles are regularly conveyed out of the dosing unit 6 through the return line 32. For this reason, it may be advantageous to have the return line 32 end in the upper area of ​​the tank interior 5. Fig. 2 shows a variant in which the return line 32 opens further down into the tank interior 5. The device according to the Fig. 3 has no return line 32.

[0048] The return line 32 in a dosing unit 6 is usually provided with an electrically adjustable return valve, which has an open state and a closed state. When the return valve is closed, the reducing agent is provided under a defined pressure. When the return valve is open, the reducing agent is circulated through the dosing unit 6 back into the reducing agent tank 2. This allows air bubbles to be efficiently removed from the dosing unit 6. It is preferred that the return valve be designed such that it is closed when there is no electrical current. This feature can also be implemented independently of the remaining features of the device according to the invention in a dosing unit 6 for a reducing agent or in an SCR dosing system.

[0049] Furthermore, in the Fig. 1 to 3 illustrate different ways of determining the fill level 37 in the reducing agent tank. Fig. 1 to 3 each show a rod electrode 29 mounted on the separated chamber 4 in the tank interior 5, which enables continuous level determination at least in one level range. The rod electrode 29 can also be mounted to the side of the separated chamber 4 in the tank interior 5. In addition, Fig. 1 and Fig. Two point electrodes 31 are provided, which can be used to determine the fill level at specific points. Between the various point-determined fill levels 27, the fill level can be determined, if necessary, by integrating the consumption. The rod electrodes 29 or point electrodes 31 can be protected by baffles 38 in the reducing agent tank. This can be particularly advantageous if ice is present in the reducing agent tank 2.

[0050] With the device 1, it should be noted that the reducing agent may contain particles that should not enter the dosing unit 6 because they could damage the components 36 of the dosing unit 6. These can be contaminants of all kinds. This is problematic with a dosing unit 6 arranged on the tank bottom 3, because particles can enter the dosing unit 6 particularly easily. For this reason, Fig. 2 and Fig. 3 different concepts for protecting the dosing unit 6 and the components 36 from such particles are presented.

[0051] Fig. Figure 2 shows that a sieve 24 is provided on the metal sleeve 14 at the opening 13 into which the dosing unit 6 is inserted. The sieve 24 separates the tank interior 5 into an inner region, which surrounds the dosing unit 6 and the separate chamber 4, and an outer region. Particles located in the outer region cannot thus enter the inner region surrounding the separate chamber 4 and the dosing unit 6.

[0052] Fig. 3 shows that a sieve 24 is provided in the immediate vicinity of a recess 39. The removal of reducing agent takes place from this recess 39. The sieve 24 can, for example, be arranged as a dome-shaped structure above the recess 39. As a further concept, a sieve 24 is provided here in the vicinity of a refill line 25, through which reducing agent can be refilled into the reducing agent tank 2. This can prevent particles that are conveyed in the reducing agent during the refilling process from becoming distributed within the tank interior 5. It is also possible here to provide a shoulder 28 in the vicinity of the sieve 24 so that reducing agent that is refilled through the refill line 25 can pass particularly easily through the sieve 24 into the rest of the tank interior 5.

[0053] To clean the reducing agent tank, the design according to the Fig. 3, a tank cap 26 is additionally provided. This tank cap 26 can also contain a tank ventilation 27. A tank cap 26 is provided in the variant according to Fig. 3 is particularly advantageous because, due to the special design of the separated chamber 4 in this variant, the reducing agent tank 2 does not have a further larger opening 13 through which the interior of the tank 5 can be cleaned.

[0054] In the Fig. 4 shows a motor vehicle 18 having an internal combustion engine 19 and an exhaust gas treatment system 20. An SCR catalyst 23 is provided in the exhaust system 20. Liquid reducing agent from a device 1 according to the invention with a metering unit 6 is supplied to the exhaust system 20 via an injector 21. The device 1 according to the invention and the injector 21 are connected to each other via a reducing agent line 22.

[0055] In the Fig. Figure 5 shows a highly simplified sketch of an embodiment of the device 1 according to the invention, in which the separated chamber 4 is designed as a pot 46 that is injected into the tank bottom 3 of the reducing agent tank 2. The reducing agent tank 2 is preferably made of plastic here. The pot 46 is preferably metallic. In this embodiment, the dosing unit 6, indicated here as a dashed box, is also provided in the separated chamber 4. The pot 46 can be closed by a lid 8. The sealing of the pot 46 and the tank bottom 3 to one another can be achieved by means of injected O-rings 34. This prevents the reducing agent from creeping along the pot 46 through the tank bottom 3 out of the tank interior 5. In the area of ​​the pot 46, O-rings can also be injected or molded into the tank bottom 3, enabling the lid 8 to be sealed to the tank bottom 3.

[0056] The Fig. 6 shows a further embodiment of the device according to the invention, in which the separated chamber 4 is removable from the tank bottom 3 of the reducing agent tank 2. The separated chamber 4 is also designed as a pot 46. The fixation or fastening of the separated chamber 4 or the pot 46 in the tank bottom 3 is achieved with an SAE closure 48. The SAE closure 48 also enables a secure sealing of the tank interior 5. In this embodiment, the dosing unit 6, indicated here as a dashed box, is also provided in the separated chamber 4. List of reference symbols 1 device 2 reducing agent tank 3 Tank bottom 4 separate chambers 5 Tank interior 6 Dosing unit 7 Withdrawal point 8 lids 9 Tank heating 10 screw connection 11 Sealing surface 12 basic bodies 13 Opening 14 metallic sleeve 15 Main floor level 16 Reducing agent outlet 17 height 18 Motor vehicle 19 Internal combustion engine 20 Exhaust gas treatment system 21 Injector 22 Reducing agent line 23 SCR catalyst 24 sieve 25 Refill line 26 fuel cap 27 Tank ventilation 28 paragraph 29 Stick electrode 30 Melting heater 31 point electrode 32 Return line 33 Clutch 34 O-ring 35 Base plate 36 components 37 Fill level 38 baffle plate 39 Deepening 40 use 41 Pump 42 filters 43 Pressure sensor 44 Temperature sensor 45 valve 46 pot 47 Stone chip protection 48 SAE cap

Claims

[1] Device (1) for providing liquid reducing agent, comprising a reducing agent tank (2) for storing reducing agent with a tank bottom (3) which has a separate chamber (4) and with a dosing unit (6) for removing reducing agent from the reducing agent tank (2) at a removal point (7) arranged on the separated chamber (4), wherein the dosing unit (6) is arranged within the separated chamber (4) and the separated chamber (4) is not filled with reducing agent. [2] Device (1) according to claim 1, wherein the dosing unit (6) is detachably connected to the reducing agent tank (2). [3] Device (1) according to one of the preceding claims, wherein the dosing unit comprises at least one component (36) from the group of the following components: - pump; - filters; - pressure sensor; - temperature sensor and ; - valve. [4] Device (1) according to one of the preceding claims, wherein the separated chamber (4) can be closed off from the environment by a lid (8) and the dosing unit (6) is fastened to the lid (8). [5] Device (1) according to one of the preceding claims, wherein the separated chamber (4) is removable from the tank bottom (3). [6] Device according to claim 5, wherein the separated chamber (4) can be fixed in the tank bottom (3) with at least one click closure: [7] Device (1) according to one of claims 1 to 4, wherein the tank bottom is made of plastic and the separated chamber (4) is designed as a pot (46) injected into the tank bottom (3). [8] Device (1) according to claim 7, wherein an O-ring is provided for sealing on the pot (46) injected into the tank bottom (3). [9] Device (1) according to one of the preceding claims, wherein the separated chamber (4) has a melt heater (30) extending away from the tank bottom (3). [10] Device (1) according to one of the preceding claims, wherein the reducing agent tank (2) is made of plastic and has at least one opening (13) which is provided with a metallic sleeve (14). [11] Device (1) according to one of the preceding claims, wherein the tank bottom (3) has a main plane (15) and the separated chamber (4) is arranged above the main plane (15). [12] Device (1) according to one of the preceding claims, wherein the tank bottom (3) has a main bottom plane (15) and the dosing unit (6) has a reducing agent outlet (16), and the reducing agent outlet (16) terminates by a height (17) of less than 50 mm [millimeters] below the main bottom plane (15). [13] Device (1) according to one of the preceding claims, wherein a stone chip protection (47) is provided below the separated chamber (4) on the device (1). [14] Motor vehicle (18) comprising an internal combustion engine (19) and an exhaust gas treatment system (20) comprising an injector (21) for reducing agent and a device (1) according to one of the preceding claims, wherein the injector (21) is connected to the device (1) via a reducing agent line (22).

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