Tank device

Abstract

Tank device (1) of a motor vehicle, in particular a reducing agent tank device, with a removal device (8) which can be arranged in an opening (7) of a tank (2) of the tank device (1) providing a liquid and which has at least one removal opening (12) for removing the liquid and at least one heating device (13), characterized in that the heating device (13) has a heating mat (14) which rests on a plurality of spaced-apart elevations (17-19) of the tank bottom (2).

Description

[0001] The invention relates to a tank device of a motor vehicle, in particular a reducing agent tank device, with a removal device that can be arranged in or on an opening of a liquid-providing tank of the tank device, which has at least one removal opening for removing the liquid and at least one heating device. State of the art

[0002] Tank devices of the type mentioned above are known from the prior art. Motor vehicles with internal combustion engines are usually provided with an exhaust gas aftertreatment system that serves to reduce pollutant emissions in the exhaust gas of the internal combustion engine. In particular, the pollutant NOx is often reduced, for which purpose the so-called SCR process (SCR = selective catalytic reduction) is used. In this process, the pollutant NOx is reduced to nitrogen and water with the aid of an aqueous urea solution. For this purpose, the liquid reducing agent is transported from a tank of the tank device via a line to a dosing module, which injects the liquid reducing agent into the exhaust gas. Since the reducing agent usually freezes at temperatures of around -11°C, it must be able to be thawed as needed, particularly in the area of ​​the extraction opening.For this purpose, it is known to provide a heating device in the tank or on the withdrawal device, which can be activated as needed. If the heating device is limited locally to the withdrawal opening, more distant areas can no longer be thawed, especially if thawed reducing agent has been withdrawn through the withdrawal opening, thus preventing favorable heat conduction to still-frozen areas of the reducing agent.

[0003] DE 10 2008 001 280 A1 describes a metering device with a heating device that has at least one surface heating system. DE 10 2006 046 900 A1 discloses a method for operating an internal combustion engine with an exhaust aftertreatment device, wherein heating elements are provided to liquefy frozen reducing agent. DE 103 19 151 A1 shows a liquid container for an aqueous urea solution with a heater surrounding the container interior.

[0004] In the not yet published DE 10 2011 088 684 A1 it is proposed to provide a fluid barrier which is intended to prevent the escape of heat in certain directions within the tank in order, for example, to concentrate the heat generated by the heating device on a certain area or to guide it in a targeted manner within the tank. Disclosure of the invention

[0005] The tank device according to the invention with the features of claim 1 has the advantage that reducing agent can still be thawed efficiently even at low fill levels. According to the invention, the heating device comprises a heating mat resting on several spaced-apart elevations of the tank floor. The tank floor thus has several spaced-apart elevations. This creates a type of relief on the tank floor consisting of elevations and depressions. The liquid located between the elevations is thawed by the heating mat as needed. The elevations on the tank floor provide the heating mat with a defined position with respect to its distance from the tank floor.The heating mat thus thaws frozen reducing agent both above and below, while the elevations on the tank bottom simultaneously counteract sloshing in the area of ​​the tank bottom, so that at low fill levels, liquid on the tank bottom is not transported away from the discharge opening by a sloshing process and can refreeze at a distance from the discharge opening.

[0006] According to an advantageous development of the invention, the elevations are circular or circular-segment shaped, with their respective center point being associated with the removal opening. The elevations thus have a relationship to the removal opening in their shape and orientation. The elevations surround the removal openings in a circular or circular-segment shape, so that the removal opening is located at their center. This has particular advantages with regard to preventing sloshing.

[0007] Particularly preferably, at least the elevation closest to the discharge opening is continuously circular or circular segment-shaped. This continuous design has the advantage that sloshing near the discharge opening is particularly advantageously avoided or prevented when low tank levels are reached. The elevation closest to the discharge opening thus forms an emergency reservoir for the reducing agent, which remains available until the end.

[0008] According to a preferred development of the invention, at least one of the remaining elevations has at least one opening. With the exception of the elevation closest to the withdrawal opening, the remaining elevations therefore have at least one opening that allows an exchange of liquid from areas remote from the withdrawal opening to areas close to the withdrawal opening. By means of a preferably provided tank bottom shape, which forms the lowest point of the tank bottom in the area of ​​the withdrawal opening, liquid reducing agent is thus always guided in the direction of the withdrawal opening, wherein, despite the provided elevations, a flow of the reducing agent to areas close to the withdrawal opening is possible. The at least one opening in each case is preferably designed as an area with a reduced height - viewed in the circumferential direction of the elevation - which is closed off at the top in particular by the heating mat.This ensures that the liquid can flow through even when the heating mat is flush with the elevation.

[0009] Preferably, the heating mat is designed to be elastically deformable. This serves in particular to ensure that the heating mat can be easily inserted into the tank. If, for example, the tank has an opening on one of its side walls whose cross-section is smaller than the heating mat, the heating mat can be elastically deformed to a size that corresponds to the dimensions of the opening and inserted into the tank. Due to its inherent elasticity, the heating mat then expands back into its original position within the tank. For example, the heating mat can be rolled up or folded before being inserted into the tank, while its inherent elasticity ensures that it unrolls or unfolds again within the tank. For this purpose, the heating mat preferably has a flexible stainless steel grid that can be contacted to the outside via stainless steel strands.The stainless steel grid is preferably surrounded by a rubber material or an elastically deformable plastic material that prevents direct contact of the stainless steel grid with the liquid inside the tank.

[0010] According to a preferred development of the invention, the heating mat has at least two different heating circuits. Depending on the operating state, one of the heating circuits or both heating circuits can be operated simultaneously. Preferably, one of the heating circuits is larger than the other, with the smaller heating circuit being assigned in particular to the dispensing opening, while the larger heating circuit extends through the entire heating mat, even into areas remote from the dispensing opening. Thus, the small heating circuit can be used to make thawed liquid available relatively quickly in the area of ​​the dispensing opening, while the larger heating circuit is switched on later, for example, to ensure a sustained liquid supply.

[0011] According to an advantageous development of the invention, the heating mat is wedge-shaped at its end facing the opening to aid removal. At its end facing the opening, the width of the heating mat thus decreases toward the opening, so that when the heating mat is pulled out of the tank, the inclined side surfaces of the heating mat ensure that the heating mat elastically deforms into a shape that allows it to be easily pulled out of the opening.

[0012] According to an advantageous development of the invention, at least one filter element is arranged on the heating mat, which extends at least substantially along the heating mat and beyond the removal opening. The filter element filters the thawed liquid before it reaches the removal opening. Because the filter element is arranged on the heating mat, during a thawing process the frozen reducing agent located between the heating mat and the filter element, which has already been filtered, is first thawed. This makes reducing agent available particularly quickly for metering into the exhaust gas of the internal combustion engine. At the same time, the filter element is also thawed quickly, so that it can fulfill its function shortly after the tank device is put into operation.

[0013] Particularly preferably, a filter element is arranged on each side of the heating mat, each extending at least substantially along the heating mat and in particular over the removal opening. This filters the thawed liquid both below and above the heating mat. According to a first embodiment, the filter element on the upper side of the heating mat extends over the removal opening, while the filter element on the underside only extends over the heating mat, wherein one or more flow openings are then provided in the heating mat, which connect the filter volume of the filter element below the heating mat and the filter element above the heating mat, such that thawed and filtered liquid below the heating mat passes through the flow openings into the upper filter volume and from there to the removal opening.

[0014] The invention will be explained in more detail below with reference to the drawings. Fig. 1 an advantageous tank device in a simplified sectional view, Fig. 2 a removal device of the tank device in a single view, Fig. 3 a plan view of a tank bottom of the tank device, Fig. 4 a plan view of a heating mat of the removal device and Fig. 5 a side view of the heating mat.

[0015] Fig. 1 shows a simplified sectional view of a tank device 1 for an exhaust gas aftertreatment system of a motor vehicle (not shown in detail here). The tank device 1 has a tank 2, which serves to provide a liquid exhaust gas aftertreatment agent 3. The tank 2 has, apart from the side walls and a top wall (not shown here), a tank bottom 4, in which a trough-shaped, open-edged receiving recess 5 is formed. Due to the trough-shaped design, the receiving recess 5 has a substantially vertically oriented side wall 6. An opening 7 is formed in this side wall 6, which opening can be arranged to receive a removal device 8 for removing the liquid exhaust gas aftertreatment agent 3 from the tank 2.

[0016] Fig. 2 shows the extraction device 8 in an enlarged detail view. The extraction device 8 has an adapter flange 9, which can be arranged in the opening 7 of the tank 2 and can be fastened to seal it tightly or, as in Fig. 1. For this purpose, a clamp 10 is pushed onto the adapter piece 9 and the side wall 6 and tightened. The opening 7 is preferably circular, with an elastomer seal advantageously being interposed between the adapter flange 9 and the side wall 6 in order to ensure secure sealing of the tank 2. It is conceivable, for example, for the elastomer seal to be vulcanized onto the adapter flange 9. In the present exemplary embodiment, the adapter flange 9 is designed in two parts, as shown by the different hatching. According to a preferred exemplary embodiment, not shown here, the adapter flange 9 is designed in one piece or in one part.

[0017] A channel 11 extends through the adapter flange 9, opening into the tank 2 at one end, forming a discharge opening 12, and leading outward at the other end. According to the present embodiment, the end of the adapter flange 9 projecting into the tank 2 is conical or wedge-shaped, thereby achieving a particularly advantageous sealing effect in the opening 7 of the tank 2. Of course, the adapter flange 9 can alternatively be cylindrical at its end 2 facing into the tank.

[0018] A heating device 13 is arranged on the adapter flange 9. This heating device is formed by a heating mat 14 molded onto the adapter flange 9. The heating mat 14 is designed as a rubber mat through which a flexible stainless steel grid 25 extends. This grid can be contacted from the outside by stainless steel strands 16 that are led outward through the adapter flange 9. Outside the adapter flange, the stainless steel strands 16 preferably merge into copper strands. This ensures that the heating device 13 is not chemically attacked by the permeation of the ammonia from the liquid exhaust aftertreatment agent into the rubber mat.

[0019] Due to the flexible design of the heating mat 14, the heating device 13 can be easily inserted through the opening 7 into the tank 2. The heating mat 14 is preferably rolled up before insertion so that it fits through the opening 7. Due to its inherent elasticity, the heating mat 14 unrolls within the tank 2 back into its essentially flat initial position. On the side facing the opening 7, the heating mat 14 has a wedge-shaped contour, tapering towards the opening 7. This ensures that the heating mat 14 can also be easily removed from the tank 2 through the opening 7. The wedge-shaped contour ensures that the heating mat 14 is automatically forced into a shape that fits through the opening 7 when pulled out.

[0020] As in Fig. 1, the tank bottom 4 has a plurality of elevations 17, 18, 19 arranged at a distance from one another, which are formed by bulges in the tank bottom 2. The elevations 17-19 and the opening 7 are aligned with one another in such a way that the heating mat 14, in the installed state, rests on the elevations 17 and thus extends across the tank bottom 4, essentially at a distance from the tank bottom 4. This gives the heating mat 14 a defined position in the tank 2, which makes it possible to thaw any reducing agent present in the tank 2 even when the fill levels in the tank 2 are low. This allows the heating device 13 to thaw frozen reducing agent both below and above the heating mat 14. Fig. 1 shows the liquid exhaust gas aftertreatment agent 3 in a partially frozen state, in which the exhaust gas aftertreatment agent 3 has thawed in the vicinity of the heating device 13 (shown in dashed lines), and is still in a frozen state in areas far away (shown by crosses).

[0021] Fig. 3 shows a top view of the tank bottom 4 of the tank 2. The elevations 17-19 formed by the bulges are, according to the present embodiment, circular segment-shaped, with their imaginary center point being associated with the discharge opening 12. The center point does not have to be directly in the area of ​​the discharge opening, as in Fig. 3. While the elevation 17 closest to the removal opening 12 is circular, the remaining elevations 18 and 19 are semicircular. According to the present embodiment, the elevations 17, 18, and 19 are each provided with several openings 20, which are formed, for example, by a partially reduced height of the respective elevations 17, 18, 19 and are arranged in particular in the area of ​​the heating mat 14. This enables fluid exchange from areas remote from the removal opening to areas close to the removal opening, even where the heating mat 14 rests on the elevations 17, 18, and 19, as in Fig. 1 shown.

[0022] According to an advantageous embodiment, which is not shown here, the elevation 17 is continuous, i.e. without an opening 20, so that sloshing at the suction point of the removal opening 12 is avoided. If, as in Fig. 1, the discharge opening 12 is arranged on the tank bottom side of the adapter flange 9, the space located beneath the heating mat 14 is essentially enclosed by the heating mat 14 resting loosely on the elevations 17, thereby at least largely preventing sloshing, particularly when cornering. Otherwise, the openings 20 allow fluid further away from the discharge opening 12 to be flushed toward the discharge opening 12 by sloshing movements.

[0023] Fig. 4 shows a top view of the heating mat 14 in a schematic representation. The heating mat 14 is shown with the stainless steel grid 15 located therein, which is guided in a serpentine manner through the heating mat 14 in order to create the largest possible heating surface. While in the present exemplary embodiment the heating device 13 has only one heating circuit, it is also conceivable to integrate two heating circuits into the heating mat 14, one being arranged relatively close to the adapter flange 9 and limited to this area, while the other extends through the entire heating mat 14. If the first heating circuit is now energized, thawed liquid is made available for suctioning off relatively quickly. The second heating circuit is only energized later in order to ensure a sustained supply of suctionable liquid exhaust gas aftertreatment agent.

[0024] While in relation to Fig. 1 it was previously assumed that the adapter flange 9 is followed by a filter element 21', which in turn is followed by a conveyor device 22, according to the embodiment of Fig. 5 shows a heating device 13 in which a filter element 21 is integrated. For this purpose, the filter element 21 is arranged on the heating mat 14 and extends substantially beyond it. Fig. 5 shows a section through the heating mat 14 along the line AA from Fig. 4. In this case, the removal opening 12 is advantageously provided on the adapter flange 9 in the area between the filter element 21 and the heating mat 14, so that the liquid is removed from the tank 2 in the filter volume between the filter element 21 and the heating mat 14. It is also conceivable to provide a filter element 21 on each side of the heating mat 14 and to connect the respective filter volumes to one another through one or more openings within the heating mat 14. While in the embodiment of Fig. 5 the filter element 21 is arranged on the upper side of the heating mat 14, it is also conceivable to provide the filter element 21 only on the underside of the heating mat 14, so that the intake opening or the removal opening 12 as in the embodiment of the Fig. 1 and Fig.2, can remain at the tank bottom side of the adapter flange 9. This makes it possible to also suck out the liquid below the heating mat 14, especially at low tank levels.

[0025] According to a further embodiment not shown here, it is conceivable to also integrate the conveying device 21 and the filter element 21' into the adapter flange 9 in addition to or as an alternative to the filter element 21 provided on the heating mat 14.

[0026] By means of the advantageous tank device 1, it is now ensured that a liquid exhaust gas aftertreatment agent is always available, which is taken from the tank 2 for removal through the removal opening 12 by means of the conveying device 22 and is supplied, for example, to a dosing module or dosing valve 23 which is assigned to the exhaust system of the motor vehicle.

Claims

[1] Tank device (1) of a motor vehicle, in particular a reducing agent tank device, with a removal device (8) which can be arranged in an opening (7) of a liquid-providing tank (2) of the tank device (1), which has at least one removal opening (12) for removing the liquid and at least one heating device (13, characterized by that the heating device (13) has a heating mat (14) which rests on several spaced-apart elevations (17-19) of the tank bottom (2). [2] Tank device according to claim 1, characterized by that the elevations (17-19) are circular or circular segment-shaped, their respective center being assigned to the removal opening (12). [3] Tank device according to claim 2, characterized by that at least the elevation (17) closest to the removal opening (12) is continuous. [4] Tank device according to claim 3, characterized bythat at least one of the remaining elevations (18,19) has at least one opening (20). [5] Tank device according to one of the preceding claims, characterized by that the heating mat (14) is designed to be elastically deformable. [6] Tank device according to one of the preceding claims, characterized by that the heating mat (14) has at least two different heating circuits. [7] Tank device according to one of the preceding claims, characterized by that the heating mat (14) is wedge-shaped at its end facing the opening (7) as a removal aid. [8] Tank device according to one of the preceding claims, characterized by that at least one filter element (21) is arranged on the heating mat (14), which extends at least substantially along the heating mat (14) and in particular over the removal opening (12). [9] Tank device according to one of the preceding claims, characterized bythat a filter element (21) is arranged on each side of the heating mat (14), which extends at least substantially along the heating mat (14) and in particular over the removal opening (12). [10] Tank device according to claim 9, characterized by that the heating mat (14) has at least one flow opening between the filter elements (21).

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