Abstract:
The invention relates to a liquid removal module ( 1 ) for removing liquid from a liquid tank ( 18 ), in particular of an exhaust gas aftertreament system of a motor vehicle, comprising a main body ( 2 ) that can be arranged in and/or on the liquid tank ( 18 ). The main body has a liquid removal device ( 36 ) having at least one removal opening ( 7 ) that can be associated with the tank interior ( 27 ) and bears at least one filter element ( 9 ) associated with the removal opening ( 7 ). The filter element ( 9 ), which is elastically deformable at least in some areas, is arranged/designed in such a way that the filter element has at least one bulge ( 17 ) directed opposite the removal flow direction ( 26 ). The invention further relates to a liquid tank ( 18 ) for a vehicle, in particular for an exhaust gas aftertreament system of a motor vehicle.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention relates to a liquid removal module for removing liquid from a liquid tank, in particular of an exhaust gas aftertreatment system of a motor vehicle, comprising a main body which can be arranged in and/or on the liquid tank and has a liquid removal device with at least one removal opening which can be associated with the tank interior and bears at least one filter element associated with the removal opening. 
         [0002]    The invention furthermore concerns a liquid tank for a vehicle, in particular for an exhaust gas aftertreatment system of a motor vehicle, having at least one wall with a tank opening, wherein in and/or on the liquid tank is arranged a liquid removal module for removing the liquid from the tank, which closes the tank opening. 
         [0003]    Liquid removal modules and liquid tanks of the type cited initially are known from the prior art. 
         [0004]    DE 10 2006 027 487 A1 discloses a liquid removal module which can be inserted in the tank through a tank opening of a liquid tank and which closes the tank opening in the manner of a lid. The liquid removal module comprises a liquid removal device with a removal opening associated with the tank interior, through which the liquid in the tank can be extracted. To deliver the liquid, the liquid removal device also comprises a pump integrated in the liquid removal module. 
         [0005]    Furthermore it is known to associate a filter element with the removal opening in order in particular to protect the pump, and the consumer of the liquid present in the liquid tank, against dirt particles or similar. Furthermore it is known to arrange the filter element on the main body having the removal opening so that the liquid removal module can be formed as a compact unit. 
       SUMMARY OF THE INVENTION 
       [0006]    The liquid removal module according to the invention has the advantage over known liquid removal modules that its function ability is guaranteed even in critical situations, in particular on a low fill level of the liquid tank and/or at low temperatures. The liquid removal module according to the invention is distinguished in that the filter element, which is deformable elastically at least in regions, is arranged/formed such that at least in regions it has a bulge oriented opposite the removal flow direction. The filter element therefore comprises at least one, preferably several bulges which are oriented opposite the removal flow direction so that liquid extracted through the removal opening flows through the bulge of the filter element opposite the direction of curvature. In other words the bulge of the filter element is formed convex viewed in the removal flow direction. The bulge and elastic deformability of the filter element, in particular in the region of the bulge, ensure that if the filter element for example is completely or partly not covered with liquid, the filter element deforms in the removal flow direction, i.e. the bulge of the filter element which was previously oriented outwards deforms into an inwardly oriented, concave bulge viewed in the removal flow direction. Instead of an uncovered filter element, as in the prior art, which prevents further extraction of liquid by drawing in air, the liquid removal module according to the invention allows further liquid removal which is definable by the size of bulge of the filter element. Thus removal of as much residual liquid as possible from the tank is ensured, which leads to an increase in the net tank volume. The net volume here means the liquid quantity which can actually be removed from the tank. This is usually smaller than the actual tank volume and is reduced further by a residual quantity which cannot be extracted. Thus at a low liquid level and in extreme driving situations, or when climbing or descending hills, the time for which the filter element or mesh is not covered with liquid is bridged. Insofar as only part of the filter element is in contact with the liquid in the tank, the liquid can be extracted because the filter element allows the liquid to pass at a lower reduced pressure than the air or gases present in the tank. In addition the dirt particles are prevented from penetrating into the filter element or mesh due to the bulge, because the dirt cannot settle permanently on the filter, for example by sedimentation. In addition, due to the bulge and elastic resilience, the risk of damage for example from ice or other mechanical stresses is excluded or at least substantially reduced. Due to the bulge, the filter area is also enlarged, and hence the filter life or safety reserves increased. 
         [0007]    Preferably for introduction of the liquid removal module into the liquid tank, the main body comprises a flange part for closing a tank opening of the liquid tank and a removal part protruding into the tank interior. The main body thus has two regions and where applicable is formed correspondingly in two pieces. The filter element and the removal opening are preferably provided on the removal part. According to a preferred embodiment the removal opening faces the tank floor while the filter element is preferably arranged above the removal opening such that it separates the floor region of the liquid tank having the removal opening from the remainder of the liquid tank. 
         [0008]    Particularly preferably the removal part has a planar grid structure which forms several openings and can be arranged in particular parallel to the floor of the liquid tank. The filter element can easily be attached to the grid structure so that it extends over the floor of the liquid tank corresponding to the outer contour of the removal part. Preferably the filter element is arranged on the top of the grid structure while the removal opening is provided on the underside of the grid structure. Particularly preferably the removal opening is formed by the grid structure itself, wherein a removal channel formed of one piece with the grid structure leads through the grid structure or removal part, in particular as far as the flange part and in particular a delivery device arranged thereon. If the filter element cannot be purged via the hydrostatic pressure of the liquid, the arrangement of the removal opening in the upper part of the filter may be advantageous because thereby the air can be extracted more easily from the filter. 
         [0009]    Preferably the filter element extends over the removal part and is formed bulging opposite the removal flow direction over at least one of the openings formed by the grid structure, in particular over each of the openings. By providing a bulge at each of the openings, the reserve volume which can be extracted from the tank by the liquid removal module, in particular if for example the filter is not covered by liquid (at low liquid level and in inclined positions and/or under acceleration forces), is increased accordingly as a whole. 
         [0010]    To form the respective bulge the filter element is preferably welded or molded to the removal part in regions or all round. Thus the filter element is suitably welded or molded to the grid structure such that the filter element bulges in the corresponding direction in the region of the opening. By selecting the molding geometry or welding points or lines on the filter element, the pretension force of the bulge of the filter element can be established. Selection of the arrangement of the molding or weld seams or weld points determines how much material of the filter element should lie superficially in the region of the respective opening. The more material lies in the region, the larger the bulge formed. 
         [0011]    According to an advantageous refinement of the invention it is proposed that the filter element comprises a filter mesh and a filter carrier, wherein the filter carrier can be/is applied structurally matching on the removal part of the main body, wherein the filter element is molded and/or welded and/or clamped to the filter carrier to form the at least one bulge. Thus for example the one or more bulges of the filter element can be produced already on production of the filter element, in that the filter mesh is recessed accordingly into the filter carrier. This simplifies the assembly of the liquid removal module. The filter element can here be clamped and/or welded and/or molded to components of the filter carrier or also between the filter carrier and the main body of the removal part to form the at least one bulge. 
         [0012]    Preferably the filter carrier and/or the removal part are formed as a heating element, in particular plastic-coated. The removal part of the main body thus assumes a double function, firstly it clamps the filter element and secondly it serves as a heating element to heat and in particular thaw frozen liquid present in the liquid tank. The filter element can thus be arranged directly on the heating element or via the filter carrier on the main body. By the formation as a heating element, in particular the liquid in the removal region i.e. close to the removal opening can be thawed when necessary and extracted from the liquid tank, wherein here the at least one bulge of the filter element allows removal of the liquid even if liquid is thawed only in the removal region and not yet outside the liquid removal module. If the liquid volume on the side of the filter element facing the removal opening diminishes, the bulge deforms in the direction of the removal opening or the removal flow direction, so that it is also ensured that no air is drawn in from outside the filter. The heating element is preferably formed as a plastic-coated aluminum body with which in particular one or more PTC heating elements are associated. 
         [0013]    According to an advantageous refinement of the invention it is proposed that the removal part is arranged eccentrically, in particular in the edge region of the flange part, and in particular extends substantially perpendicular to the flange part. The eccentric arrangement of the removal part on the flange part guarantees that the removal part and in particular the removal opening are arranged as far down in the liquid tank or as close to the tank floor as possible. Preferably the removal part and the flange part for this are arranged offset to each other in their height position so that a side opening can be formed in the liquid tank in a region of the side wall of the liquid tank advantageous for the opening, and the removal part nonetheless can be arranged on the tank floor. Naturally it is also conceivable to arrange the removal part and flange part parallel to each other and introduce them into the tank volume through a tank opening formed in the tank floor. 
         [0014]    Particularly preferably the filter element surrounds the removal part of the main body which has the removal opening. The filter element is thus arranged not only in one plane, but preferably in at least two planes, above and below the removal opening so that the filter element surrounds a volume associated with the removal opening so that where applicable only liquid filtered in several stages can enter the removal opening. One or more bulges of the filter element can be provided on both the top and on the underside. 
         [0015]    The liquid tank according to the invention is characterized by the formation of the liquid removal module as described above. This leads to the advantages already described above. Particularly preferably at least the flange part and the wall of the liquid tank are made of the same material, in particular from the same plastic, to allow simple and secure welding of the two elements to each other. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    The invention will now be described below with reference to the drawing which shows: 
           [0017]      FIG. 1  a liquid removal module in a perspective view; 
           [0018]      FIG. 2  an enlarged detailed view of a liquid removal module in a perspective view; 
           [0019]      FIG. 3  a section view of the liquid removal module; 
           [0020]      FIG. 4  an underside view of an alternative embodiment of the liquid removal module; 
           [0021]      FIG. 5  a liquid tank with the liquid removal module; 
           [0022]      FIG. 6  an assembly position of the liquid tank; 
           [0023]      FIG. 7  a heating element of the liquid removal module in a perspective view; 
           [0024]      FIG. 8  a section view through the liquid removal module according to an advantageous refinement; 
           [0025]      FIG. 9  a refinement of the liquid removal module in a perspective view, and 
           [0026]      FIG. 10  a flange part of the liquid removal module in perspective view. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]      FIG. 1  shows in a perspective view a liquid removal module  1  which serves for installation in a liquid tank of an exhaust gas aftertreatment system of a motor vehicle. For this the liquid removal module  1  has a main body  2  which comprises a flange part  3  and a removal part  4 . Preferably the main body  2  is made of high density polyethylene or HDPE plastic. The flange part  3  is formed as a lid and for this has a circular contour. The removal part  4  has a planar grid structure which extends substantially parallel to the flange part  3  or parallel to its axis. The flange part  3  and the removal part  4  are connected together via a push-fit connection but can also be connected as one piece or in another manner. A removal channel  5  also extends through the removal part  4  and opens into a removal opening  7  arranged on the underside  6  and at the other end transforms into a removal connection  8  which is formed on the outside of the flange  3 . The removal opening  7  in the present case is arranged centrally on the end of the removal part  4  remote from the flange  3 . The removal opening  7  and removal channel  5  are formed of one piece by the removal part  4  which is advantageously made as a plastic part. In principle it is conceivable to provide another or several further removal openings which open into the same removal channel  5  or further removal channels which lead through the removal part  4  or main body  2 . 
         [0028]    The removal part  4  is furthermore surrounded by a filter element  9  which surrounds the removal part  4  over its full periphery and protrudes at the side beyond the removal part  4 . The removal opening  7  thus lies inside the filter element  9 . On the top side  10  of the removal part  4  is arranged a heating element  11  which has a plastic-coated aluminum base body. The heating element  11  is formed structurally matching with the removal part  4  so that the heating element  11  has the same planar grid structure as the removal part  4  so that the two can be arranged aligned on each other. In the present embodiment example the filter element  9  lies with a region between the heating element  11  and the removal part  4 . Naturally an embodiment is also conceivable in which the filter element  9  also surrounds the heating element  11 . The heating element  11  has connection contacts  12  which protrude outward through the flange part  3  so the heating element  11  can be contacted electrically from the outside, for example with a plug. 
         [0029]    The removal channel  8  and removal opening  7  and where applicable the delivery device mounted on the flange part  3  together form a liquid removal device  36  of the liquid removal module  1 . 
         [0030]      FIG. 7  shows the heating element  11  in a perspective view. The connecting lines  13  forming the connection contacts  12  are also coated with plastic on production. In the middle region, several PTC heating elements  14  are provided in receiver pockets of the plastic sheathing and/or aluminum base body and are connected electrically with the connecting lines  13 . When power is applied to the PTC heating elements they heat up, wherein their heat is transmitted by the aluminum base body and distributed accordingly. 
         [0031]      FIG. 2  shows a liquid removal module  1  in a perspective top view onto the top  10  of the removal part  4 . The filter element  9  in the present embodiment example consists only of a filter mesh  15  which is formed elastically deformable. The openings  16  formed by the grid structure of the heating element  11  and the removal part  4  are covered by the filter mesh  15 , wherein the filter mesh  15  or filter element  9  has a bulge  17  in the region of the respective opening  16 . The bulges  17  point away from the top  10  of the removal part  4 . To create the bulges  17 , the filter mesh  15  or filter element  9  is glued or molded or preferably welded to the receiver part  4 . It is also conceivable to clamp the filter element  9  between the heating element  11  and the receiver part  4  such that the bulges  17  exist permanently. 
         [0032]      FIG. 3 , for clarification, shows the liquid removal module  1  in a section view through the grid structure. Here the bulges  17  are clearly evident in the region of each opening  16 . Due to the structural similarity of the heating element  11  and removal part  4 , these together form in each case one of the openings  16 . According to an alternative embodiment, the filter element together with the heating element  11  can form a preassembly group such that the filter element  9  is attached, in particular glued or welded, to the heating element  11  forming the bulges  17 . Then the heating element  11  need merely be placed on the top  10  of the removal part  4 . 
         [0033]    According to the embodiment example of  FIG. 4 , it is also conceivable to form the grid structure substantially by the heating element  11  alone. It is also conceivable that the filter element  6  or filter mesh  15  lies closely on the removal part  4  and/or heating element  11 , as shown in  FIG. 4 . Preferably here corresponding bulges  17  are formed over at least some of the openings  16 . 
         [0034]      FIG. 5  shows the arrangement of the liquid removal module  1  in a liquid tank  18 . The liquid tank  18  comprises a wall  19  which on one side has a first tank opening  20  and on the top a second tank opening  21 . The opening  21  is closed by a purge unit  22  inserted therein, which will not be discussed in more detail here. 
         [0035]    The tank opening  20  is closed by the flange part  3  of the liquid removal module  1 . Due to the formation of the liquid removal module  1 , the removal part  4 , by its lateral insertion into the liquid tank  18 , extends substantially parallel to the tank floor  23  which is provided with corrugated dirt traps  24 . The removal opening  7  thus faces the tank floor  23 . Preferably the removal part  4  lies with its underside  6  on the tank floor in regions. Preferably the removal part on its underside  6 , as shown in  FIGS. 1 and 2 , has several recesses  25 , of which here only some carry reference numerals. The recesses  25  allow the penetration of liquid into the removal region located inside the grid structure when the removal part  4  lies on the floor  23 , even if the floor  23  were formed flat. If the recesses  25  are provided, the filter element  9  or filter mesh  15  advantageously surrounds the entire removal part so that it is ensured that liquid which passes through the recesses  25  into the removal region is also filtered. Substantially the liquid is however drawn through the filter mesh arranged on the top  10  when the liquid is extracted from the liquid tank  18  via the removal opening  7  and removal channel  5 , as indicated by arrows  26 . If recesses  25  are not provided, it is guaranteed that the liquid flows into the removal region substantially through the openings  16 . 
         [0036]    The bulges  17  are formed curving opposite the removal flow direction. This has the advantage that firstly the filter area is enlarged and secondly it is more difficult for dirt particles to settle on the filter  9 . In addition, by the elastic design of the filter element  9 , the bulges  17  have the effect that on removal or extraction of liquid from the tank  18 , these can yield and for example deform such that they curve in the opposite direction, preventing air from being drawn into the filter interior or the removal region. The bulges  17  thus form a type of reserve which allows further extraction of liquid, in particular on low fill levels of the liquid tank, without air being drawn in. This is advantageous in particular at low temperatures which could lead to freezing of the liquid present in the liquid tank  18 . 
         [0037]    Whereas in the advantageous embodiment examples, bulges are shown only on the top  10  of the removal part  4 , in a preferred embodiment it is provided that one or more bulges are also provided on the underside  6  of the removal part  4 , which also curve opposite the removal flow direction or in the direction of the tank floor  23 , whereby further liquid is provided for extraction from the tank floor  23 . In addition it is conceivable that the filter mesh has slight undulations, folds or similar forms which serve to enlarge the area and relieve stress, in particular on freezing of the liquid in the tank. 
         [0038]    The removal part  4  is arranged on an edge region of the flange part  3  so that the centre axes of the removal part  4  and flange part  3  are arranged offset to each other. This allows a favorable positioning of the removal part  4  and hence the removal opening  7  on the tank floor  23 .  FIG. 6  for this shows an assembly step for mounting the liquid tank  18  with the liquid removal module  1 . The preferably circular tank opening  20  has a diameter which allows the removal part  4  to be inserted in the tank interior  27  together with the heating element  11 . As soon as the removal part  4  is in the tank interior  27 , the liquid removal module  1  is shifted in the direction of the tank floor  23 , as indicated by an arrow  28 , until the flange part  3  is arranged coaxial to the tank opening  20 . Then the liquid removal module  1  is pressed as far as the stop, i.e. until the flange  3  lies on the wall of the liquid tank  18 . Preferably then the flange part  3  is welded or glued to the wall  19  of the liquid tank  18  to guarantee a sealed and secure connection. In principle it is also conceivable to provide the tank opening  20  in the tank floor  23  and orient the flange part  3  and removal part  4  substantially parallel to each other so that in the fitted state, the removal part  4  lies on the tank floor  23  and the flange part  3  closes the tank opening  20  in the tank floor  23 . It is also conceivable that the removal part  4  is formed directly by the flange part  3 , and the heating element and filter element  9  extend over the flange part  4 . This is particularly preferred for installation of the liquid removal module  1  in a tank opening which is formed in the tank floor  23 . 
         [0039]    As an alternative to the embodiment shown here of the liquid removal module for lateral arrangement on the liquid tank  18 , in a preferred embodiment not shown here, the liquid removal module is formed for arrangement on/in a tank opening formed in the tank floor  23 . In this case the removal part  4  also has a circular base area and is arranged parallel to the flange part  3 . Particularly preferably the flange part  3  co-forms the removal part  4 . 
         [0040]    The liquid tank  18  has a depression  35  leading from the tank opening  20  to the tank opening  21 , in which can be laid in particular a heated pressure line of the delivery device described above which leads to the purge unit  22  and only from there in the direction of a consumer. Thus by heat cavity formation in a completely frozen liquid tank  18 , this can economically be changed. 
         [0041]      FIG. 8  shows an advantageous refinement of the liquid removal module  1  in which the filter element  9  surrounding the removal part  4  has one or more intermediate filter elements  29  which are preferably made of the same filter mesh  15  or a finer or coarser filter mesh. The filter elements  29  preferably extend from the top of the filter to the underside of the filter, transversely and/or longitudinally through the filter element  9 .  FIG. 8  shows an intermediate filter element  29  which extends transversely through the filter element  9 . Such intermediate filter elements  29  thus form an additional filter stage. 
         [0042]      FIG. 9  shows a further embodiment of the liquid removal module in a perspective exploded view. According to this embodiment the filter element  9  is formed by a filter carrier  30  and a filter mesh  31  held by the filter carrier  30 . The structure of the filter carrier  30  corresponds to the grid structure of the heating element  11  and removal part  4 , so that it further forms the openings  16 . In the region of the openings  16  the filter mesh is formed such that in each case it forms a further bulge  17  which is oriented or curved opposite the removal flow direction, i.e. in the direction of the tank floor  23 . The filter element  9  shown in  FIG. 9  and the bulges  17  can thus be pre-assembled into a preassembly group and then connected with the removal part  4  and/or heating element  11 . Naturally it is also conceivable to provide a first filter element  9  on the underside of the removal part  4  and a corresponding second filter element on the free top side of the heating element  11 , the bulges  17  of which are curved in the opposite direction. It is also conceivable to connect in series two filter elements  9  as shown in  FIG. 9 . In a further embodiment only some or even only one of the openings  16  is provided with bulged filter element regions. 
         [0043]      FIG. 10  shows an advantageous embodiment of the flange part  3  which has several screw threads  32  to receive a delivery device. The screw holes  32  are each fitted with two retaining elements  33  protruding in a shaft-like manner, which ensure that the delivery device predominantly loads the screws axially so that smaller screws or a smaller number of screws can be used. The screw holes  32  are preferably not threaded, so that the screws can be screwed directly into the flange part  4  made of plastic. 
         [0044]    In an embodiment example not shown here, the receiver channel  5  preferably runs directly through the heating element  11  and is preferably formed through its plastic molding. Thus the heating element  11  itself forms the removal part  4 . According to a further embodiment the removal channel  3  and removal opening  7  are formed by the filter carrier  30  or a filter carrier mounted otherwise. 
         [0045]    The connection lines  13  are preferably themselves formed as heating lines so that in particular when arranged close to the receiver channel  5 , these can also be heated and where applicable thaw frozen liquid. Alternatively or additionally at least one connection line  13  can be designed as passive heating of the removal channel  5 . The heat is then distributed from the PTC elements and/or aluminum body of the heater via the lines along the removal channel  5 . 
         [0046]    Due to the planar grid structure of the heating element  11 , a large quantity of liquid can be thawed. The filter element can also be molded when the aluminum body of the heating element  11  is coated. Then the lower filter side is folded over and for example connected to the removal part  4  or a separate filter carrier by welding, wherein the seal must be guaranteed only on the edge region of the filter carrier and the region of the support surface. It is also conceivable that a filter element  9  forming a construction unit as shown in  FIG. 9  can be fixed by releasable connection, for example by catches, to the receiver part  4  and/or heating element  11 . The intermediate filter elements then also serve as protection inside the filter element  9 . The spaces between different filter layers of the filter element  9  can be guaranteed by spacers. 
         [0047]    By contact of the filter element with the heating element  11 , the heat emitted by the heating element  11  can be transferred directly into the filter element  9  so that this is rapidly thawed and ready for operation. Due to the low filter height or small spacing between the different filter layers and a small spacing from the tank floor  23 , it is possible to shift the heating element  11  close to the tank floor  23  so that forces acting on the heating element  11  are reduced and the resulting possible movement of the heating element reduced. Thus the heating element  11  will rapidly freeze at temperatures below freezing point and thus be protected by ice against possible damage from liquid enclosed in the ice, which expands on freezing. In addition, due to its own small height, the heating element  11  can reduce the effective forces. By defined support surfaces of the liquid removal module  1 , defined pressure forces can be exerted on the tank floor  23  during assembly, whereby tolerances of form, position, angle and flatness of the liquid removal module  1  and the liquid tank  18  in the interface region can be compensated. Preferably the connecting interfaces between the different elements of the liquid tank  18  and/or the liquid removal module  1  are designed such that over the entire life, at least one support surface is in contact with the tank floor  23 . The connection between the removal part  4  and the flange part  3  is preferably made elastically deformable so that tolerances can be compensated and preferably the removal part  4  pressed in the direction of the tank floor  3  in the fitted state. For this the rib  34  is provided which runs between the flange part  3  and removal part  4 . The rib  34  is preferably formed of one piece with the removal part  3  and lies in a recess of the heating element  7 . The interface between the rib  34  and flange part  3  is preferably formed by welding, mirror welding or similar methods. 
         [0048]    In addition it is also conceivable to provide the liquid removal module  1  with a fill level sensor and/or a return. 
         [0049]    By utilizing surface tensions and capillary effects, and by corresponding choice of filter material mesh and geometric design of the filter element  9 , the volume of non-extractable liquid in the liquid tank  18  with a flat tank floor  23  without a pump sump can be substantially reduced. 
         [0050]    The advantageous embodiment of the filter element  9  described above ensures that if the filter element  9  is briefly not completely in the liquid, the liquid removed from the filter interior or the removal region can be extracted by the yielding or deformation of the filter material  9  or bulges  17  even if air penetration into the chamber region is prevented by the liquid residue still adhering to the outside of the filter element  9  and/or liquid retained due to filter unevenness. Preferably the tank floor  23  has a slope in the direction of the removal direction  7 .