Container with a heating device for a tank for storing a liquid additive

Abstract

Container (1) for a tank (2) for storing a liquid additive (3), comprising a housing (4) with a heating device (5), wherein at least one driveable apparatus (6) for promoting convection is provided in the housing (4) and wherein the housing (4) has an inner wall (38) and an outer wall (39) forming an intermediate space (40) in which at least one partially closed flow path (41) for a convection flow is formed.

Description

The present invention relates to a container for a tank for storing a liquid additive, comprising a housing with a heating device. Such a container serves in particular for receiving functional components for conveying and / or metering and / or monitoring the liquid additive on the way from the tank through the container to a consumer. The invention is used in particular in a motor vehicle which is provided with a tank for storing a liquid additive, wherein the container is integrated into the tank there.It is to be regarded as known that methods for exhaust gas after-treatment are used in which liquid additive is added to the exhaust gas. This is intended in particular to ensure that the pollutants contained in the exhaust gas are converted as completely and efficiently as possible.For example, it is known to add an oxidizing agent (for example, to the exhaust gas. Fuel or hydrocarbon) may be added. This additive can be used to react directly with constituents of the exhaust gas and thus to react pollutants. However, it is also possible for this oxidizing agent to be used to convert ambient conditions in the exhaust system into a desired state suitable for the conversion of pollutants. Thus, fuel or hydrocarbon can be supplied to an oxidation catalyst, wherein the temperature of the exhaust gas in the exhaust system can be significantly increased due to an exothermic reaction in the oxidation catalyst. This serves in particular for regenerating a diesel particle filter.It is also known to supply a reducing agent to the exhaust gas. Although it is possible in principle to introduce solid or gaseous reducing agent into the exhaust system, conveying systems and metering systems have proven particularly suitable, which bring about a liquid supply of the reducing agent. For example, the method of selective catalytic reduction is known (SCR: selective catalytic reduction). In this case, nitrogen oxide compounds are reacted in the exhaust gas with the aid of the reducing agent. For this purpose, ammonia or ammonia-forming substances can be used in particular. A reducing agent which is already widely used for this purpose is urea-water solution. A 32.5% urea-water solution is known under the trade name AdBlue ®. This liquid additive is then first added to the exhaust gas and then passed over a suitable catalyst in which the desired chemical conversion then takes place (inter alia).Particularly with regard to mass production in automobile construction, no particularly cost-effective and simple configuration of a conveying module or metering module for these additives has yet been found here. For reasons of space and to avoid damage in the event of freezing, it has already been proposed to arrange such a metering module, for example, in the base region of a tank for storing the liquid additive. In order to also facilitate retrofitting of already known systems or to enable separate manufacturing steps, such conveying modules or metering modules are accommodated in a separate container. This can be permanently or releasably connected to the tank.Since, for example, liquid additive, such as urea-water solution, already freezes at temperatures around -11 ° C., heating systems have been proposed which are intended to achieve rapid thawing of the liquid additive in the tank and / or a connected conveying line. The desired exhaust gas purification method should thus be available already quickly after engine start of a motor vehicle and / or damage to the components required for storing, delivering and / or adding the liquid additive should be avoided.As heating devices, liquid heaters (e.g., heat exchangers that cooperate with the engine cooling system), electric heaters, radiant heaters, and combinations thereof have already been proposed in this technical field. However, the quickest possible and possibly even possible heating in the container could not yet be achieved satisfactorily. In particular, the proposed systems for heating the container are technically complicated, cost-intensive and / or difficult to regulate or control.DE 10 2012 104 551 A1 discloses a container for a tank for storing a liquid additive, comprising a housing with a heating device, wherein at least one drivable apparatus for promoting convection is provided in the housing. In particular, a motor vehicle is also disclosed, having a tank for storing a liquid additive and an exhaust system having an addition device for the liquid additive, wherein such a container is inserted into the tank wall and a plurality of functional components for conveying the liquid additive from the tank through the container to the addition device is provided therein.DE 10 2008 005 196 A1 discloses a tank removal system for a vehicle tank which is filled with a frozen liquid. The tank extraction system comprises a heating system which has at least one electric heating element as primary heating device, and a line system which is provided with at least one extraction line having an extraction opening arranged in the vehicle tank. The cold start volume of frozen liquid extending around the extraction opening is fusible by the primary heating device. In order to melt a cold starting volume as quickly as possible and to melt the remaining frozen liquid as energy-saving as possible, it is provided that the heating system has a secondary heating device fed with a heating fluid and the power system has at least one heating line, through which the heating fluid can flow and which is arranged in the liquid in the vehicle tank, and that the heating line is connected to the extraction line in a liquid-conducting manner and the melted liquid can be fed as heating fluid through the extraction line to the heating line.DE 10 2008 000 549 A1 discloses an exhaust gas purification device which converts nitrogen oxides contained in the exhaust gas of an internal combustion engine into harmless components by reduction with ammonia on a catalytic converter. Ammonia is formed from urea water contained in a tank and injected into an exhaust pipe. The urea water contained in the tank is stirred by a stirring device to make the temperature and density thereof uniform in the tank, thereby preventing the urea water from partially freezing in the tank. The urea water can be heated in addition to the stirring thereof, thereby securely preventing the urea water from freezing.In the light of the above-described situation, it is an object of the present invention to at least partially solve the problems described with respect to the prior art. In particular, a container for a tank for storing a liquid additive is to be specified, which permits cost-effective, simple and efficient heating. Furthermore, a particularly advantageous and space-saving integration of a heating system into a motor vehicle is to be proposed.These objects are achieved with a container according to the features of claim 1. It should be pointed out that the features listed individually in the patent claims can be combined with one another in any desired, technologically meaningful manner. The description, in particular in conjunction with the figures, explains the invention and specifies further combinations of features and advantageous embodiments of the invention.The container for a tank for storing a liquid additive comprises a housing with a heating device, wherein at least one drivable apparatus for promoting convection is provided in the housing and wherein the housing has an inner wall and an outer wall which form an intermediate space in which at least one partially closed flow path for a convection flow is formed.By configuring flow paths in this way within the housing, a particularly effective transfer of the heat, which originates from the heating device, to the functional components and to the liquid additive in the tank is possible.The container is in particular designed such that it can be accommodated at least partially and preferably almost completely in a tank for storing the liquid additive. In this case, the tank volume should be reduced by the integration of the container into the tank, for example, by a maximum of 20%, preferably a maximum of 10%. The tank is in particular a tank for storing a reducing agent, in particular urea-water solution. However, this could also be used for oxidizing agents and other liquid additives. The container can be made of plastic. In any case, the tank should be stable and designed for permanent storage of the liquid additive. The housing can be embodied here in one part or in multiple parts. It is possible that, for example, a pot-shaped housing and an additional container base are provided, which are connected to one another in a releasable or non-releasable manner. The housing can be made of plastic and / or metal. In any case, in the region of the housing which is in contact with the interior of the tank, the housing should be resistant to the liquid additive.The container further comprises at least one heating device, which is arranged in particular in the housing or the container space formed by the housing. The heating device can in principle be any of the types of heating devices mentioned at the beginning. It is preferred here that the heating device itself only occupies a small proportion of the container space, for example less than 20% of the container space or even less than 10% of the container space.Furthermore, a drivable apparatus for promoting convection is provided in the housing. The drivable apparatus has in particular the function of distributing the heat generated by the heating device in the housing by means of convection. It is preferred that the drivable apparatus itself is not in direct contact with the heating device, but rather distributes the heat emitted by the heating device as uniformly as possible by convection by influencing the air flow in the interior of the container. Here, convection is understood to mean, in particular, (the targeted) movement of air in the container. Air is therefore moved by means of the drivable apparatus towards the heating device, so that the latter can heat up on contact with the heating device. The heated air then flows, likewise motivated by the drivable apparatus and / or flow guide elements, into other (predefined) regions of the container free space. In this case, the heated air comes into contact with the housing and / or components positioned in the housing, so that here a heating can take place quickly.In order that this can be effected effectively, the apparatus can be activated and deactivated as required. In this respect, the apparatus is designed and / or configured such that it can be driven (and moved) at predetermined or desired times. Therefore, the phases in which convection is promoted in the casing can be accurately set.With such a device, the problems described at the beginning can be at least partially alleviated. At the same time, a rapid heating of the container and / or of the surrounding region of the container in the tank can be achieved.The apparatus of the container may be used (in addition) to effectively cool at least one component in the container. A component which may require cooling is, for example, a pump for delivering and / or metering liquid additive. During operation, such a pump may heat up strongly. This heat can be transported away from the pump with the aid of the apparatus and can be dissipated, for example, via the housing into the liquid additive in a tank.According to a preferred embodiment variant of the container, at least one self-contained flow path exists in the housing, along which flow path the apparatus can generate an in particular circulating air flow. The circulating air flow is convection which is conveyed with the apparatus. The flow path is formed by free spaces within the housing and, if appropriate, by corresponding flow guide elements. Free spaces are regions in the housing in which no components or functional components are arranged. These therefore offer space for the flow path. The flow path preferably runs along the heating device and along the regions to be heated (in particular the functional components) in the container or in the housing.The flow path runs along a wall of the housing. Thus, the air flow via the wall of the housing can release heat to the liquid additive in the tank. The housing can be designed and / or used at least in sections as a flow guiding element. The wall of the housing is preferably at least partially cylindrically shaped, and the flow is continuously directed onto a path along the wall by the curvature of the cylindrical shape of the wall. According to one embodiment variant, there are two closed flow paths in the housing, which flow paths each run along a section of the housing wall. At least one first deflection point is provided on the housing wall, at which the flow paths are deflected away from the housing wall into an inner region of the housing. In the inner region of the housing, a heat exchange takes place between the air stream and the functional components. There is at least one second deflection point at which the flow paths are deflected again toward the wall of the housing. The first deflection point and the second deflection point are each formed with the aid of a first deflection means or with the aid of a second deflection means. The deflecting means deflect the flow at the deflecting points. The deflecting means are flow guiding means. In the region along the housing wall and / or in the inner region of the housing, the flow paths run at least along an apparatus which is configured to drive an air flow along the flow paths or to promote convection along the flow paths. In addition, the flow paths run along the housing wall in the region and / or along the heating device in the inner region of the housing, so that a heat exchange can take place between an air flow along the flow paths and the heating device.The housing has an outer wall which separates the housing or the container from the tank in a fluid-tight manner, and an inner wall which runs at least in regions parallel to the outer wall. Between the outer wall and the inner wall, a gap-shaped space is provided through which an air stream can flow. The outer wall and the inner wall are preferably spaced apart from each other by at least one spacer element. The spacer elements may also aid in heat transfer between the inner wall and the outer wall and air flow. The spacer elements can act in particular as impact elements, on which the air flow in the intermediate space impinges and to which the air flow therefore has a particularly good heat transfer. The apparatus is preferably arranged to force the air flow generated by the apparatus into the interspace through at least one inflow opening in the inner wall. A flow path preferably extends starting from the apparatus through the at least one inflow opening into the intermediate space and subsequently starting from the intermediate space through at least one outflow opening back into an interior space of the housing. This interior space is bounded by the inner wall of the housing. A heating device may be arranged, for example, between the apparatus and the inflow opening of the inner wall of the housing, such that the air conveyed by the apparatus, directly after it has been heated by the heating device, reaches the interspace and heats liquid additive in the tank which surrounds the housing.Thus, a plurality of heating devices and apparatuses for promoting convection can also be arranged in a described container, wherein these can respectively form partial or independent flows along different flow paths. These different flow paths can each be configured to flow in a targeted manner onto specific regions and / or functional components within the container or the housing in order to heat these regions and / or functional components particularly quickly.The flow speed of the air along the flow paths can be adjusted by a suitable configuration of the free space within the housing available for the flow paths. The larger the available free cross section, the lower the flow velocity. The functional components and flow paths are preferably arranged in the housing such that the thermal energy generated by the heating device is (practically) fully emitted to the air flow, and the air flow in turn (practically) fully emits the thermal energy to the functional components and the housing.According to a further development, it is also proposed that the at least one drivable apparatus comprises a blower and a blower motor connected thereto.In this embodiment variant, the drivable apparatus can be provided particularly cost-effectively and in a technically simple manner. It is thus possible, for example, for the blower motor to be activated at the desired times via a control unit and (later) deactivated again. The blower can comprise, for example, a type of rotor with which the air in the container is moved. Thus, the fan can be aligned in particular such that the air moved from it is moved towards the heating device. In principle, a plurality of fans can be provided with one fan motor or one fan motor each. However, from the viewpoint of cost reduction, it is preferable to use a single blower having a single blower motor. It is very particularly preferred that the container has only one single drivable apparatus.It is furthermore preferred that the heating device has a single electrically operable heating element in the housing. An electrically operable heating element can likewise be activated and deactivated at predefined times. This is effected, for example, on the basis of ohmic resistance heating. A known electrically operable heating element which can be used particularly preferably here is a so-called PTC heating element (PTC: positive temperature coefficient). The configurations of such PTC heating elements have long been known, so that additional information regarding this is readily available to the person skilled in the art.A container is considered to be advantageous in which the heating device protrudes at least partially over its entire circumference freely into the housing. Thus, the heating device can be designed, for example, in the manner of an at least partially free-standing flange, an at least partially free-standing column or the like. It is obvious that such a heating element is connected at least to the container bottom and / or the housing in order to withstand a secure positioning of the heating device even under high dynamic stress (such as, for example, during driving operation in the motor vehicle). Also, via this contact, power lines, control lines and the like are realized. The configuration of the heating element which protrudes at least partially over its entire circumference freely into the housing, however, allows the air which is moved from the drivable apparatus toward the heating device to be able to flow and / or even flow around the heating element over a large area. This allows intensive contact of the air in the container with the heating device, so that the heating device can quickly absorb heat and subsequently be distributed. Preferably, at least 50% of the circumferential surface of the heating device is free of internals, so that direct contact with the ambient air in the container space is made possible. This proportion can preferably also be at least 60% or even at least 80%.It is furthermore proposed to additionally provide a plurality of functional components in the container for conveying the liquid additive from the tank and through the container. In this case, the container serves in particular for receiving a conveying module and / or metering module for the liquid additive. In this case, the delivery module or metering module can remove liquid additive from the tank at specified times and / or in specified amounts and lead it out of the tank via the container. Examples of such functional components are: a delivery line, an inlet (e.g. a section of the delivery line via which the liquid additive is delivered from the tank to a pump), an outlet (e.g. a part of the delivery line with which the liquid exhaust gas is led out of the container by a pump), a return (e.g. a part of the delivery line with which liquid additive located in the container is guided back into the tank again), a pump, a filter, a sensor, a control unit and the like. In particular, the container is designed and configured such that an air flow is generated by means of the drivable apparatus, said air flow initially passing the heating device and subsequently flowing through at least a plurality of the functional components in the container, such that said functional components can at least partially absorb the heat carried along with the air flow. Consequently, these functional components are heated by convection in the housing.It is very particularly preferred that the housing consists at least partially of plastic. The use of a plastic housing has the advantage that the production costs can be reduced and weight can be saved. In the case of the container proposed here, it must also be taken into account that the distribution of heat within the container due to convection no longer absolutely requires that many heat bridges for heat conduction are formed within the container.It is also considered advantageous that the housing has at least one inner rib. If necessary, several ribs can also be provided. The rib is in particular designed as a (passive) heating rib and thus serves in particular for intensive contacting of the heated air. The rib can be configured to absorb heat by convection and optionally also transfer this heat into other regions of the housing. The rib is designed to protrude from the housing inner wall, i.e. in particular to protrude into the free space of the container. The rib could also be referred to as a wing, web, projection or the like, wherein the surface is many times larger than the cross section. Orientation, shape and / or material of the rib can be adapted to a specific purpose.It is particularly advantageous if the ribs are aligned in accordance with the direction of flow of the air in the housing. The ribs should extend in particular parallel to the flow direction, so that on the one hand a particularly good heat transfer between the ribs and the air is achieved and on the other hand the flow resistance caused by the ribs is as low as possible. The ribs should in particular be oriented parallel to the flow direction of the air or convection. This can be achieved, for example, by ribs on the housing which extend at least in sections in a circular manner along the inner side of the (cylindrical) housing. If the air circulates (driven by the apparatus) according to a flow path which runs at least in sections along the inner side of the housing, a particularly good heat transfer is possible between the air and ribs on the inner side of the housing. At the same time, such circular ribs can form portions of a flow path for the air through the housing. The flow is guided by the ribs along the wall of the housing.The ribs increase the (inner) surface of the housing and thus facilitate the heat transport from the inside to the outside. The ribs can be made of a material with particularly good thermal conductivity.In particular, it is possible for the ribs to be manufactured from a different material than the further housing. In addition, it is possible that the ribs extend through the housing and lead to an outer side of the housing in a tank for the liquid additive, wherein the ribs have an increased thermal conductivity. Such fins can transfer heat particularly well into the liquid additive in the tank.Furthermore, a motor vehicle is also proposed here which has a tank for storing a liquid additive. The tank has a tank wall that defines a tank volume. Furthermore, the motor vehicle has an exhaust system with an addition device for the liquid additive. In addition, a container proposed here is inserted into the tank wall, wherein a plurality of functional components for conveying the liquid additive from the tank, through the container to the addition device, are provided therein. The motor vehicle is thus designed in particular for carrying out the methods described at the beginning for exhaust gas aftertreatment. The system solution proposed here with a cost-effective and efficient heating for the container, the functional components and / or the tank is to be emphasized here in particular.The invention and the technical field are explained in more detail below with reference to the figures. It should be noted that the embodiments illustrated in the figures are not intended to limit the invention. In particular, the features shown and explained together in the figures can also be considered separately from one another and / or be combined with other (individual) features of other figures, provided this is not technically possible or, below, the association of features is not explicitly pointed out as obligatory. Accordingly, a large number of possible combinations of the invention illustrated schematically and by way of example in the figures will be apparent to the person skilled in the art.The following are shown: FIG. 1 is a partial perspective view of a container, FIG. 2 : a schematic sectional view of a tank with a container, FIG. 3 : shows a schematic view of a motor vehicle with tank and exhaust system, FIG. 4 : shows a schematic section through an embodiment variant of a housing for a container, FIG. 5 : shows a schematic section through a further variant embodiment of a housing for a container, FIG. 6 : shows a schematic section through yet another variant embodiment of a housing for a container, and FIG. 7 : shows a schematic section through yet another variant embodiment of a housing for a container.Accordingly, FIG. 1 shows a container 1, which can be inserted, for example, into a tank for storing the reducing agent, such as urea-water solution. The container 1 comprises a pot-like housing 4 which is round in cross section and forms the circumferential surface and the lid. At the bottom, the container 1 is closed off by a container base 20, wherein the container base 20 can be designed, for example, as a separate component which is connected detachably or non-detachably to the remaining (pot-shaped) housing 4. In the interior of this container 1, the so-called container space is partially filled by various functional components 10 for conveying the liquid additive from the tank through the container 1. These functional components 10 are shown here in dashed lines in order to indicate that they can optionally be arranged individually or in any meaningful combination with one another in the container free space 25.In the container space, a conveying module or dosing module is indicated here by way of example. The liquid additive is thus taken from the tank via an inlet 17. This can be effected by a corresponding suction effect of the pump 21 connected thereto. Starting from the pump, the delivery line 16 continues as far as a valve 29. From this valve 29, it can be predetermined according to requirements whether the liquid additive, which is now under pressure, is delivered further to an outlet 18, for example to an exhaust system, and / or to a return 19, via which the liquid additive can now be introduced back into the tank. For the controlled operation of this delivery module or dosing module, a control unit 24 can be provided which adjusts the operation of the pump, the valve and / or further functional components via signal lines indicated here. This control unit 24 can also perform this operation as a function of one or more sensors 23. Thus, for example, a pressure sensor for the pressure of the liquid additive in the conveying line 16 and / or a temperature sensor for determining the temperature of the liquid additive in the conveying line 16 and / or for determining the temperature of a functional component or in the container free space 25 can be used as sensor 23.Also shown centrally is an individual heating device 5, which is designed here in the manner of an electrically operable heating element 9 (e.g. a PTC heating element). In this embodiment variant, the electrically operable heating element 9 can likewise be activated and deactivated as required by the control unit 24. It can be easily seen that the electrically operable heating element 9 predominantly protrudes freely over its entire circumference into the housing 4, so that here an air flow (indicated by the arrows) can be brought well into contact with the electrically operable heating element 9.In order to now achieve convection and thus a distribution of the air located in the housing 4, a drivable apparatus 6 is furthermore provided, which is here exemplarily embodied with a blower 7 and a blower motor 8 associated therewith. Here, too, it is possible for the control unit 24 to drive or slow down the blower 7 via the blower motor 8 as required or at specified times.The function is now in particular such that during operation of the apparatus 6, the air located in the container clearance 25 is moved towards the heating element 9, which is indicated by a vertically patterned arrow. When the air flow contacts the heating device 5, the air is heated and can then be supplied to remote regions of the housing 4 and / or to one or more functional components 10. For this purpose, flow guide elements 28 (baffle plates or the like) can be provided in / on the heating device 5 and / or in the container clearance 25 in order to realize a directed distribution or conveyance of convection in the container 1. The air flow generated by the drivable apparatus 6 can be divided up as desired and passed on in different directions. The heated airflow is also represented by arrows having a horizontal pattern.FIG. 2 schematically shows a tank 2 for storing the liquid additive 3. The tank wall 13 delimits the so-called tank volume 12. A major part of the housing 4 of the container 1 thus extends into the tank volume 12 of the tank 2. A (cylindrical) filter 22 is provided around the container 1, wherein the functional components 10 draw off the additive 3 in a region of the tank 2 in which (practically only) filtered additive 3 is present. In principle, the filter 22 can also be integrated into the container or the conveying line located therein.FIG. 2 also shows that a plurality of heating devices 5 can be arranged in the container 1. These are positioned here, for example, flat in the manner of strips on the inside of the housing and / or of a functional component. Furthermore, it is illustrated here by way of example that an individual drivable apparatus 6 is arranged and set up in the container in such a way that it brings about an air flow via a plurality of heating apparatuses 5.Also illustrated schematically in FIG. 2 are a plurality of ribs 33 in the manner of a (passive) heating rib which serves for intensive contacting of the heated air. The ribs 33 are arranged, for example, distributed on the inside of the housing 4, in particular concentrated at the location at which the air heated by the blower 7 is directed.FIG. 3 now also shows a motor vehicle 11, for example a passenger car or a truck, wherein the exhaust gas generated by an internal combustion engine 27, in particular a diesel engine, is guided along an exhaust gas flow direction 31 through an exhaust system 14. In particular, for carrying out the so-called SCR method, the liquid additive is added to the exhaust gas (finely distributed or with a conveying gas). If a sufficient distribution of the additive in the exhaust gas and / or a sufficient conversion of urea-water solution into ammonia is realized, this mixture is supplied to a suitable exhaust gas aftertreatment unit (such as an SCR catalyst) 26. This can be designed, for example, in the manner of a coated honeycomb body. This can be provided in particular with a suitable coating. When the additive-exhaust gas mixture flows through the catalytic converter 26, the desired chemical and / or thermal processes can be motivated.The liquid additive is stored in a tank 2 and added in metered fashion to the addition device 15 by means of the functional component(s) provided in the container 1 and via a suitable conveying line 16. The quantity and / or the time of addition can be predefined by a controller 32, wherein in particular operating parameters of the internal combustion engine 27, the exhaust system 14 and / or the conveying system (tank, container, conveying line, addition device, etc.) are effected here. The metering can be effected via the functional components of the container 1 and / or of the addition device 15.FIG. 4 shows a horizontal section through a housing 4 for a container 1. schematically the apparatus 6 in the housing 4 is shown, with which the convection in the housing 4 can be promoted. According to convection, air flows are formed in the housing 4 by the operation of the apparatus 6, which flow circulates according to the closed flow paths 41. These flow paths 41 run at least in sections along a wall of the housing 4. The air flow is thus in direct heat exchange with the housing 4. a first deflecting means 42 is arranged in the housing 4 which deflects the flow paths 41 away from the housing 4 into an interior space 44 of the housing 4 (first deflecting point 45). Functional components not shown here can also be arranged in this interior. The flow paths 41 run from the first deflecting means 42 through the interior space 44 and are subsequently deflected by the second deflecting means 43 back to the housing 4 (second deflecting point 46), so that the flow paths 41 are produced as self-contained paths. In the region of the interior space 44, the flow paths 41 run past an apparatus 6 which conveys or drives the convention or the air flow. The apparatus 6 includes a blower 7 and a blower motor 8 that drives the blower 7. In addition, the flow paths 41 in the interior space 44 run along a heating device 5. the heating device 5 can comprise an electrically heatable heating element 9 and additional heating ribs 34, via which the heat of the heating element 9 is dissipated. The heating device 5 is preferably designed such that there is a good heat transfer to the air flow and at the same time as low a flow resistance as possible occurs when the flow passes around the heating device 5. Preferably, the apparatus 6 presses the air flow directly onto the heating device 5, without a deflection of the air flow being provided between them. This improves the heat transfer.FIG. 5 shows a horizontal section through a further embodiment of a housing 4 for a container 1, and in this embodiment, two flow paths 41 are also provided in the housing 4, which flow paths are guided through the housing 4 with the aid of a first deflecting means 42 and a second deflecting means 43 corresponding to the flow paths shown in FIG. 4. In order to save space in the interior space 44 of the housing 4, according to FIG. 5 two apparatuses 6 are provided, each of which comprises a blower 7 and a blower motor 8 and are arranged on the sections of the flow paths 41 on the wall of the housing 4. The heating device 5 is designed as a baffle element onto which the apparatuses 6 press the air flow. The heating device 5 has an electrically operable heating element 9 and heating fins 34 which distribute the heat produced by the electrically operable heating element 9. At least the first deflecting means 42 or the second deflecting means 43 can be designed as a structural unit together with the heating device 5.FIG. 6 shows a vertical schematic section through a housing 4 for a container 1. this housing 4 has ribs 33 on its inner side (for example substantially horizontal and / or helical), which delimit the flow paths 41 which run through the housing 4 along the wall of the housing 4. These ribs 33 align the flow paths 41 along the wall of the housing 4. In addition, the ribs 33 provide improved heat transfer between the air circulating along the flow paths 41 and the housing 4.Fig. 7 shows a horizontal section through a housing 4 for a container 1, with a more detailed representation of the wall according to the invention. In this embodiment variant, the housing 4 consists of an inner wall 38 and an outer wall 39. the outer wall 39 seals the housing 4 in a fluid-tight manner and is in contact with its outer side with the liquid additive (such as urea-water solution) when the housing 4 is inserted into a tank. The inner wall 38 and the outer wall 39 are spaced apart from each other so that a space 40 exists between the inner wall 38 and the outer wall 39. Spacer elements 35 can be provided, which position the inner wall 38 and the outer wall 39 relative to each other and possibly also serve for forming flow paths. The inner wall 38 may be partially interrupted so that permeable connections exist from the space 40 into the interior space 44 of the housing 4. In the housing 4 is disposed an apparatus 6 having a blower 7 and a blower motor 8. This apparatus 6 is configured to suck in an air flow from the interior space 44 and to guide it into the intermediate space 40. For this purpose, the inner wall 38 has an inflow opening 36. The air flow is guided from the apparatus 6 through the inflow opening 36 and the intermediate space 40 and leaves the intermediate space 40 again at at least one outflow opening 37 in the inner wall 38. The air flow then passes through the inner space 44 back to the apparatus 6. Between the apparatus 6 and the inflow opening 36 a heating device 5 is arranged along which the air flow flows according to the flow path 41. The heating device 5 may comprise an electrically operable heating element 9 and heating fins 34 which effectively pass the heat produced by the electrically operable heating element 9 to the air flow. On the outside of the housing 4 there are ribs 33 via which the heat of the liquid additive in a tank can be transferred.The embodiment variants shown here show preferred combinations of technical features which, however, do not necessarily have to be combined with one another. Insofar as this is not explicitly stated above, the technical features can be extracted from a figure and can be combined with other concepts / variant embodiments without problems for the person skilled in the art. This applies in particular with regard to the configuration / arrangement / number of apparatuses, flow paths, housings and heat transport measures (ribs etc.).The invention thus solves the object set at the beginning to at least partially solve the problems described with reference to the prior art. In particular, a container for a tank for storing a liquid additive such as urea-water solution has been specified, which enables cost-effective, simple and efficient heating. Furthermore, a particularly advantageous and space-saving integration of a heating system into a motor vehicle has also been shown.List of reference characters1 Container 2 Tank 3 Additive 4 Housing 5 Heating device 6 Apparatus 7 Blower 8 Blower motor 9 Electrically operable heating element 10 Functional component 11 Motor vehicle 12 Tank volume 13 Tank wall 14 Exhaust system 15 Addition device 16 Feed line 17 Inlet 18 Outlet 19 Outlet 20 Container base 21 Pump 22 Filter 23 Sensor 24 Control unit 25 Container clearance 26 Exhaust gas aftertreatment unit 27 Internal combustion engine 28 Flow guide element 29 Valve 30 Opening 31 Exhaust gas flow direction 32 Controller 33 Rib 34 Heating rib 35 Spacer element 36 Inflow opening 37 Outflow opening 38 Inner wall 39 Outer wall 40 Intermediate space 41 Flow path 42 First deflecting means 43 Second deflecting means 44 Inner space 45 First deflecting point 46 Second deflecting point

Claims

Container (1) for a tank (2) for storing a liquid additive (3), comprising a housing (4) with a heating device (5), wherein at least one drivable apparatus (6) for promoting convection is provided in the housing (4) and wherein the housing (4) has an inner wall (38) and an outer wall (39), which form an intermediate space (40), in which at least one partially closed flow path (41) for a convection flow is formed.Container (1) according to claim 1, wherein the at least one drivable apparatus (6) comprises a blower (7) and a blower motor (8) connected thereto.Container (1) according to claim 1 or 2, wherein the heating device (5) comprises in the housing (4) a single electrically operable heating element (9).Container (1) according to one of the preceding patent claims, wherein the heating device (5) protrudes at least partially over its entire circumference freely into the housing (4).Container (1) according to one of the preceding patent claims, wherein a plurality of functional components (10) for conveying the liquid additive (3) from the tank (2) and through the container (1) is additionally provided in the container (1).Container (1) according to one of the preceding patent claims, wherein the housing (4) is at least partially made of plastic.Container (1) according to any of the preceding claims, wherein the housing (4) comprises at least one inner rib (33).Motor vehicle (11), having a tank (2) for storing a liquid additive (3) with a tank wall (13) forming a tank volume (12) and an exhaust system (14) with an addition device (15) for the liquid additive (3), wherein a container (1) according to one of the preceding patent claims is inserted into the tank wall (13) and a plurality of functional components (10) for conveying the liquid additive (3) from the tank (2), through the container (1) to the addition device (15) is provided therein.

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