Filter cartridge for a reducing agent delivery device

Abstract

Filter cartridge (1) for a conveying device (2) for a reducing agent, comprising at least one filter wall (3) and at least one supporting wall (4) which, together with the filter wall (3), forms an interior space (15), wherein the at least one supporting wall (4) has a drain opening (8) and a bypass opening (10), wherein the drain opening (8) can be coupled to the conveying device (2) and the bypass opening (10) forms a bypass to the filter wall (3), and the reducing agent is a urea-water solution.

Description

[0001] The invention relates to a filter cartridge for a reducing agent conveying device and a conveying device for reducing agents.

[0002] Exhaust gas treatment systems, into which a reducing agent is fed, are also used to clean the exhaust gases of internal combustion engines. In such exhaust gas treatment systems, the reducing agent can be used to reduce certain pollutants in the exhaust gas particularly effectively. So-called SCR catalysts are particularly frequently used in these systems; in these catalysts, nitrogen oxide compounds in the exhaust gas are converted with the aid of ammonia. Ammonia is not usually stored directly in motor vehicles, but in liquid form, also known as a reducing agent precursor solution. A frequently used reducing agent precursor solution is urea-water solution, which is sold, for example, under the trade name AdBlue. ®with a urea content of 32.5%. The reducing agent precursor solution can be converted into the actual reducing agent in the exhaust gas treatment device and / or in an exhaust gas-external generator. The term "reducing agent" is also used below for reducing agent precursor solutions and the like.

[0003] To deliver the reducing agent to the exhaust gas treatment system, motor vehicles are usually provided with a suitable delivery device that delivers the reducing agent from a tank. A problem with the design of such delivery devices is that the reducing agent may contain contaminants, and the delivery device should therefore provide means for filtering the reducing agent. This is achieved, for example, by means of replaceable filter cartridges provided in the delivery device. Another problem is that the aqueous reducing agent can freeze. The reducing agent AdBlue ®For example, it freezes at -11 °C. Such low temperatures can occur particularly during extended downtimes of an internal combustion engine. Therefore, freezing results in an increase in volume. If only limited space is available for the increase in volume, the increase in volume manifests itself in a drastic increase in pressure. This is referred to as ice pressure. A delivery device for reducing agents must therefore be designed and operated in such a way that it is not damaged by the freezing of the reducing agent or by the described increase in volume and ice pressure. This has proven particularly problematic in the area of ​​the filter in a delivery device.

[0004] DE 11 2009 000 102 T5 discloses a filter comprising a housing with an inlet that receives dirty fluid to be filtered and an outlet that discharges clean, filtered fluid. Furthermore, the filter comprises a filter element within the housing that filters the fluid, wherein the filter element has an upstream side that receives fluid along an upstream flow path from the inlet and a downstream side that discharges fluid along the downstream flow path to the outlet. The housing comprises an upstream chamber that communicates with the upstream side of the filter element, wherein the housing further comprises a downstream chamber that communicates with the downstream side of the filter element, and further comprises an elastically compressible reservoir.

[0005] US 2010 / 0 140 155 A1 discloses a filter assembly comprising a filter cartridge having a first filter element and a second filter element. The first filter element comprises a first tubular portion of filter media extending between first and second end caps and defining a first open filter interior. The second filter element comprises a second tubular portion of filter media operatively aligned within the first open filter interior. The second tubular portion of filter media extends between the third and fourth end caps and defines a second open filter interior. The first end cap defines an inner container and an outer container surrounding the inner container. The outer container is attached to the first tubular portion of filter media. The inner container has an end wall axially spaced from the outer container.The filter assembly further includes a housing for the cartridge and can be either a spin-on or a cartridge-type filter. The filter assembly is usable in a hydraulic system that includes a sump, a device valve, a pump, and a filter head in fluid communication with the sump, the device valve, the pump, and the filter assembly.

[0006] DE 10 2010 054 349 A1 discloses a replaceable filter element for filtering a liquid, in particular for filtering the oil of an oil circuit of an internal combustion engine. The filter element comprises a filter insert for the flow of the liquid to be filtered, as well as a cylindrical central tube for supporting the filter insert. In the filter element, a sieve is attached to the central tube, which closes an end opening of the central tube and has a sieve body that is peripherally sealed and, in particular, permanently connected to the central tube.

[0007] DE 10 2009 039 735 A1 discloses a conveying device for conveying liquid reducing agent with at least one first compensation element, wherein the conveying device for conveying, conveying and adding a reducing agent comprises at least one reducing agent tank, a conveying unit as well as a reducing agent line and an addition unit, which together have a total volume that can be filled with reducing agent, wherein the at least first compensation element is suitable for reducing the total volume in the case of a negative pressure in the conveying device.

[0008] The object of the present invention is to solve these described technical problems as comprehensively as possible. In particular, it is intended to provide a filter cartridge that is particularly well protected against damage when the reducing agent tank in a conveying device freezes. Furthermore, it is intended to present a conveying device that is also particularly well adapted to the changing conditions inside during and after the reducing agent freezes.

[0009] These objects are achieved with a filter cartridge according to the features of patent claim 1 and a conveying device according to the features of patent claim 8. Further advantageous embodiments of the invention are specified in the dependent claims. The features listed individually in the claims can be combined with one another in any technologically expedient manner and can be supplemented by explanatory facts from the description, thereby demonstrating further embodiments of the invention.

[0010] According to the invention, a filter cartridge for a conveying device for a reducing agent, comprising at least one filter wall and at least one supporting wall which together with the filter wall forms an interior space, wherein the at least one supporting wall has a drain opening and a bypass opening, wherein the drain opening can be coupled to the conveying device and the bypass opening forms a bypass to the filter wall and the reducing agent is a urea-water solution.

[0011] A filter cartridge has at least one filter wall and at least one support wall. One filter wall is permeable to the medium to be filtered (liquid reducing agent) and has small openings or pores for this purpose.

[0012] Filter walls also preferably have the largest possible surface area and the smallest possible wall thickness to ensure the lowest possible flow resistance for the medium to be filtered through the filter wall. The filtering effect of a filter wall is determined by the opening size or pore size of the filter wall. The filter wall is designed to retain particles in the medium to be filtered that are larger than the opening size or pore size. The opening size or pore size is preferably substantially uniform across the entire filter wall to achieve a uniform filtering effect across the entire surface.

[0013] Due to the flow resistance of the filter wall, a pressure difference develops between the interior of the filter cartridge and an exterior area around the filter cartridge during normal operation with the usual conveying device. This pressure difference drives the reducing agent through the filter wall during operation and is determined by the flow resistance of the filter wall and the volume flow of reducing agent through the filter wall. During normal operation, this pressure difference is typically small compared to the ice pressures that occur (in the event of freezing), for example, less than 0.1 bar. During operation, the reducing agent in a filter cartridge is sucked from the exterior area into the interior. The pressure present in the interior is therefore normally lower than the pressure outside during operation.When the conveying device is out of operation or is in a pause during which no reducing agent is being conveyed, there is (virtually) no volume flow of reducing agent through the filter wall. Therefore, at these times, there is also no pressure difference between the interior and exterior of the filter cartridge.

[0014] The filter wall alone is often not able to provide the filter cartridge with sufficient mechanical stability. Due to its large surface area and low wall thickness, the mechanical stability of the filter wall is typically low. Therefore, the filter cartridge is designed with at least one support wall, which can permanently specify the position of the filter wall and, for example, encloses and / or frames the filter wall (partially or completely). The support wall, for example, specifies a cartridge shape of the filter cartridge in which the at least one filter wall is fitted in such a way that the support wall frames the filter wall. Support walls are impassable for the medium to be filtered and have sufficient wall thickness and strength to maintain the shape of the filter cartridge or to determine the shape and position of the filter wall of the filter cartridge. Support walls are preferably made of plastic.A filter cartridge also has (at least) one drain opening in the area of ​​a supporting wall, with which the filter cartridge can be coupled to a conveying device.

[0015] The filter cartridge forms an interior space which is in particular only delimited by the supporting walls and filter walls. The interior space forms in particular a reservoir for already filtered reducing agent which, as required, can be removed via the drain opening of one of the supporting walls and fed to the conveying device. It is preferred that the large side surfaces of the side walls / filter walls essentially define the interior space and the small edges of the side walls / filter walls create the connection with one another. A filter cartridge in a conveying device for reducing agent thus preferably forms a type of hollow body which delimits an interior space and is surrounded by an exterior side. The reducing agent can, for example, be sucked in from the exterior side through the filter wall into the interior space formed by the filter cartridge.When a filter cartridge freezes, the reducing agent remaining in it usually freezes from the filter wall toward the center of the hollow body or the center of the filter cartridge's interior. Because the center of the filter cartridge freezes last, a particularly high ice pressure regularly builds up inside the filter cartridge.

[0016] The invention discussed here is based on the idea of ​​providing (at least) one bypass opening in a supporting wall of a filter cartridge so that (already filtered) reducing agent can flow back from the interior of the filter cartridge to an exterior of the filter cartridge, where in particular unfiltered reducing agent is still present. The bypass opening is preferably always open so that at a predetermined overpressure in the interior, reducing agent can escape from the interior at any time. A bypass opening next to the filter wall serves in particular as an "emergency release" of reducing agent in the event that an undesirably high pressure builds up in the interior, particularly in the event of freezing. In the event of freezing, such a bypass opening enables, for example, ice pressure building up in the filter cartridge to be dissipated from the interior of the filter cartridge.When the filtered reducing agent freezes outside the interior and continues inward, a kind of ice shell forms, enclosing an ever-shrinking (still liquid) volume of reducing agent. The bypass opening is positioned centrally to ensure contact with this remaining (still liquid) volume of reducing agent in the event of freezing and ultimately ensure drainage from the ice shell to the outside, thus preventing a dangerously high pressure buildup.

[0017] The bypass opening is a very cost-effective solution for reducing pressure from the interior because no (flexible and / or pre-stressed) compensation means or similar devices are required on the filter cartridge to reduce ice pressure. The bypass opening can be created very cost-effectively by simply drilling a hole. It is particularly advantageous if only a single bypass opening is provided. It should also be noted that the bypass flow of the reducing agent is negligible during normal operation, particularly because the filter wall has a sufficiently low flow resistance. The flow resistance is particularly low when the surface area of ​​the filter wall is particularly large and the thickness of the filter wall is particularly small. In addition, similar materials (e.g., a sponge, a grid, a sieve, etc.) can also be used.) are positioned outside the bypass opening, which represent a flow resistance and thus limit or almost prevent the bypass flow during normal operation.

[0018] In the area of ​​the drain opening of the filter cartridge, a coupling device is particularly advantageously provided, via which the drain opening can be coupled in a fluid-tight manner to a correspondingly provided counterpart at an opposite opening on the conveying device. A coupling device can be designed, for example, as a click lock or a screw lock. In a particularly advantageous embodiment, the coupling device is designed to be detachable from the conveying device, so that the filter cartridge can be detached from the conveying device without being damaged. The filter cartridge is also advantageously replaceable, so that several filter cartridges can be used in the conveying device over the service life of a conveying device.

[0019] In a further advantageous embodiment of the filter cartridge, the bypass opening has a second diameter that is less than one-tenth (1 / 10) of the first diameter of the drain opening. The bypass opening is thus significantly smaller than the drain opening. The bypass opening preferably has a cross-sectional area that is less than one-hundredth (1 / 100) of the cross-sectional area of ​​the drain opening. The bypass opening is designed to be small compared to the drain opening so that, for example, the bypass flow is relatively small but sufficient for the desired pressure reduction in the event of freezing.

[0020] Furthermore, it can be advantageous if the bypass opening is covered by a sieve element. In other words, this means, in particular, that exactly one sieve element is positioned on the outside of the filter cartridge so that it spans the bypass opening. On the one hand, a sieve element can protect the bypass opening. On the other hand, a sieve element can also provide a certain degree of shielding for impurities in the reducing agent in the area of ​​the bypass opening. It is preferred that the openings in the sieve element are several times larger than the (largest) openings / pores in the filter wall.

[0021] It is also advantageous if the sieve element is welded or vulcanized onto the supporting wall. The technical process of "vulcanization" is known to those skilled in the art. This specifically refers to the fact that the sieve element and / or a fastening aid (bonding tape, etc.) are at least partially made of a rubber material that is treated under increased pressure and elevated temperature for a certain period of time, whereby the rubber material in particular solidifies (and possibly shrinks) and results in a permanently strong connection (e.g. similar to an adhesive bond) between the sieve element and the supporting wall. It is also possible for the sieve element to be glued or clamped to the supporting wall. The sieve element can, for example, be made of plastic.Such a plastic sieve element can be attached to the retaining wall very cost-effectively using a welding process, especially if the retaining wall is also made of plastic, because welding plastic usually requires only very little technical effort and, in particular, very low welding temperatures.

[0022] Furthermore, it is advantageous if the bypass opening has a second diameter of at least 100 µm [micrometers]; preferably even at least 200 µm [micrometers] and particularly preferably at least 500 µm [micrometers]. Reducing agent in conveying devices normally freezes when the conveying device is at a standstill and there are no vibrations in the conveying device. Therefore, it is possible for the reducing agent present in the conveying device to be cooled below the freezing point of the reducing agent in liquid form and then to freeze abruptly or suddenly upon slight vibration. For this reason, the pressure and volume increase resulting from freezing occur relatively quickly. Therefore, it is necessary for the bypass opening to have a diameter capable of quickly reducing the ice pressure occurring during freezing.Therefore, a minimum diameter within the specified range for the bypass opening is very advantageous to reduce the resulting forces. Furthermore, the minimum diameter should be selected so that the bypass opening is not blocked by frozen reducing agent.

[0023] In a further design variant of the filter cartridge, the filter wall forms a (substantially) cylindrical basic shape. Furthermore, an upper side and a lower side are each formed by a supporting wall, with the drain opening arranged on the upper side and the bypass opening on the lower side. The upper side and the lower side are usually aligned perpendicular to an axis of symmetry of the cylindrical basic shape. The terms “upper side” and “lower side” do not define a preferred installation orientation of the filter cartridge in a conveying device, but rather only refer to the spatial arrangement of the individual wall sections of the filter cartridge in relation to one another. It is possible to install the filter cartridge in a conveying device with any orientation of the axis of symmetry (e.g. horizontal, vertical or diagonal).A filter cartridge designed in this way often freezes starting from the peripheral surface, so that an increasingly smaller inner region containing liquid reducing agent forms in a cylindrically shaped ice shell. In this region, the pressure continues to rise due to the increase in volume of reducing agent during freezing. This pressure cannot be relieved towards the drain opening because the drain opening is connected to the conveying device. There is normally only a limited volume in the conveying device into which the increasing pressure could be reduced. In addition, valves or similar devices are often provided in the conveying device to prevent the ice pressure and the increase in volume from being passed on to the conveying device. In addition, the conveying device may already be blocked by frozen reducing agent if the ice pressure in the filter cartridge increases.It is therefore advantageous to provide the bypass opening on the opposite underside of the filter cartridge. This bypass opening is often oriented toward a relatively large volume filled with (unfiltered) reducing agent, e.g., positioned at a distance from the bottom of the filter housing and / or in contact with a compensation element. Such compensation elements can, for example, be compressible inserts made of rubber (like a sponge) or similar materials. It is also possible to provide a type of compressible bellows, which can be filled with air, for example. The pressure transmitted through the bypass opening can therefore be dissipated into this external space.

[0024] The upper support wall and the lower support wall can be connected to each other through the interior of the filter cartridge by at least one connecting structure or by at least one support structure. This support structure can, for example, be designed in the manner of a basket, which has openings through which the reducing agent can pass (so that there is no significant flow obstruction here) and simultaneously supports the filter wall from the inside or from the interior.

[0025] According to a further advantageous variant of the filter cartridge, the support wall has a receptacle in which a compressible insert is arranged. This receptacle and the compressible insert are preferably provided on / at the outside of the filter cartridge. The receptacle and the compressible insert are preferably provided on the filter cartridge where a bypass opening is also located. It is also particularly advantageous if the bypass opening, the receptacle, and the compressible insert are provided on the underside of a cylindrically shaped filter cartridge. This underside is usually opposite the top side, on which a drain opening and, if applicable, a coupling device are located. Ice pressure building up inside the filter cartridge can thus be dissipated via the bypass opening to the outside and into the compressible insert. The receptacle and the compressible insert usually do not seal the bypass opening.This allows a reducing agent flow (bypass flow) through the bypass opening and, for example, past the compressible insert to the outside of the filter cartridge. The insert preferably sits loosely or loosely in / on the receptacle.

[0026] Within the scope of the invention, a conveying device for a reducing agent is also claimed, which has a suction point and a discharge point, wherein a conveying path for the reducing agent is formed from the suction point to the discharge point, which conveying path runs at least through a filter cartridge described according to the invention.

[0027] The filter cartridge or the filter wall of the filter cartridge thus divides the conveying path into a first path section from the intake point to the filter wall and a second path section from the filter wall to the discharge point. A pump and (various) valves, which are provided for conveying the reducing agent in the conveying device, are preferably located in the second path section, so that they are protected from impurities in the reducing agent by the filter cartridge or the filter wall. From this perspective, the interior of the filter cartridge is to be assigned to the second path section, so that practically only filtered reducing agent is present in the second path section. The external space around the filter cartridge or the filter wall is to be assigned to the first path section. The bypass opening forms a bypass from the second path section to the first path section without the flow having to pass through the filter wall.The bypass opening allows the filter wall to be bypassed. Pressure that occurs inside the filter cartridge or in the second path section can be dissipated via the bypass opening to the outside space around the filter cartridge or to the first path section.

[0028] In this context, it is not necessary for the filter cartridge to be detachable from the conveying device. It is also possible for the filter cartridge to be an integral component of the conveying device and / or to be permanently or, in particular, irremovably connected to other components of the conveying device. The filter cartridge can be welded, soldered, or stamped into the conveying device, for example.

[0029] Within the scope of the invention, a motor vehicle is also claimed, comprising an internal combustion engine, an exhaust gas treatment device for purifying the exhaust gases of the internal combustion engine, and a conveying device according to the invention for conveying reducing agent into the exhaust gas treatment device. Such a motor vehicle, in particular, also has a tank for liquid reducing agent (e.g., urea-water solution), from which the conveying device can convey the reducing agent.

[0030] The invention and the technical environment are explained in more detail below with reference to the figures. The figures show particularly preferred embodiments, to which the invention is not limited, however. It should be noted that the figures, and in particular the proportions shown, are only schematic. They show: Fig. 1: a first design variant of a filter cartridge, Fig. 2: a second design variant of a filter cartridge, Fig. 3: a third variant of a filter cartridge, Fig. 4: a cross-section through a filter cartridge, Fig. 5: a fourth design variant of a filter cartridge, Fig. 6: a fifth variant of a filter cartridge, Fig. 7: a conveyor device, and Fig. 8: a motor vehicle having a conveyor device.

[0031] The Fig. 1, Fig. 2, Fig. 3, Fig. 5 and Fig. 6 show five different embodiments of the filter cartridge 1 according to the invention. The filter cartridge 1 according to the Fig. 1, Fig. 2, Fig. 3 and Fig. 5 each has a cylindrical basic shape 14, which is formed by the filter wall 3. In the filter cartridge 1 of Fig. 6, the basic shape 14 is conical. The filter wall 3 forms a type of peripheral surface of the basic shape 14. On the upper side 16 and on the lower side 17, the basic shape 14 is each closed off by a support wall 4. The filter cartridges 1 are preferably each approximately rotationally symmetrical to an axis of symmetry 7. The filter wall 3 each has an upper edge region 5 and a lower edge region 33. The upper edge region 5 and the lower edge region 33 each form an edge of the filter wall 3. There, the filter wall 3 is connected to the support walls 4. Thus, the support walls 4 preferably frame the filter wall 3. The filter wall 3 and the support walls 4 delimit the individual filter cartridges 1 according to the Fig. 1, Fig. 2, Fig. 3, Fig. 5 and Fig. 6 each have an interior space 15 of the filter cartridge 1.

[0032] On the upper side 16 in the support wall 4, a drain opening 8 is provided, via which the filter cartridge 1 can be connected to a conveying device (such as a pump). The drain opening 8 is particularly surrounded by a coupling device 9, via which the filter cartridge 1 can be connected, preferably in a fluid-tight and detachable manner, to an intake opening on a conveying device corresponding to the drain openings 8.

[0033] A freezing direction 6 indicated by arrows shows in the Fig. 1, Fig. 2, Fig. 3, Fig. 5 and Fig. 6 indicates in which direction the ice can preferably spread when the reducing agent freezes. Ice initially forms on the outer filter walls 3. This creates a space (cylindrical, conical, round, etc.) containing liquid reducing agent, which is surrounded by a layer of ice (ice jacket). In the design variant according to Fig. 6, the remaining space of liquid reducing agent in the interior 15 is also more conical. The ice layer then expands toward the center of the interior 15. Preferably, the center of the interior 15 then freezes faster at the top 16 than at the bottom 17. This allows the ice pressure to build up toward the bypass opening 10 on the bottom 17.

[0034] The bypass opening 10 on the underside 17 of the filter cartridge 1 is in the Fig. 1, Fig. 2, Fig. 3, Fig. 5 and Fig. The design variants of the filter cartridge 1 shown in Figure 6 are each designed differently. Although (preferably) only a single bypass opening 10 is provided per filter cartridge 1, several bypass openings may also be provided.

[0035] According to Fig. 1, the bypass opening 10 on the underside 17 is a simple bore with a second diameter 12, which is preferably substantially smaller, in particular ten times smaller than a first diameter 11 of the drain opening 8.

[0036] According to the Fig. 2, the bypass opening 10 is also designed with a second diameter 12, which is smaller than a first diameter 11 of the drain opening 8. In addition, according to Fig. 2 a sieve element 13 is provided which covers the bypass opening 10.

[0037] In the version according to Fig. 3, the bypass opening 10 has a shoulder 31. Due to the shoulder 31, the support wall 4 in the bypass opening 10 tapers towards the interior (in sections). This design of the bypass opening 10 makes it possible to manufacture the bypass opening 10 particularly cost-effectively and precisely. This can be done, for example, using a hot mandrel that pierces the support wall 4 of the filter cartridge 1 to create the bypass opening 10.

[0038] In Fig. 5, a bypass opening 10 is also formed on the underside 17. Opposite the bypass opening 10, a receptacle 32 is provided on the outside of the underside 17, in which a compressible insert 27 is received. Ice pressure, which develops in the interior 15 of the filter cartridge 1 and is released via the bypass opening 10, can be diverted into the compressible insert 27.

[0039] In Fig. 6, the bypass opening 10 is corresponding to the Fig. 1 executed. Fig. 6 only shows the conical shape of the filter cartridge 1 as a special feature.

[0040] The various special features and characteristics of the design variants of the filter cartridge 1 according to the Fig. 1, Fig. 2, Fig. 3, Fig. 5 and Fig. 6 can be combined with each other as desired.

[0041] In the Fig. 4 shows a section through an embodiment of the filter cartridge 1, which is shown along the section line AA in the Fig. 3 is indicated. In Fig. 4, the filter wall 3 of the filter cartridge 1 can be seen. The filter wall 3 has a wave structure 29. By means of such a wave structure 29, a particularly large filter surface of the filter wall 3 can be realized with a relatively small space requirement for the filter cartridge 1. Also visible is the underside 17 of the filter cartridge 1, which can be Fig. 4 along the axis of symmetry 7. On the underside 17, the supporting wall 4 with the bypass opening 10 can be seen.

[0042] In Fig. Figure 7 shows a variant of the conveying device 2, into which a filter cartridge 1 according to the invention is inserted. The filter cartridge 1 is inserted into a cartridge receptacle 28 provided on the conveying device 2. A conveying path 20 exists through the conveying device 2, starting from the suction point 18 and going to the discharge point 19. The conveying path 20 is divided by the filter cartridge 1 or the filter wall 3 of the filter cartridge 1 into a first path section 21 from the suction point 18 to the filter wall 3 and into a second path section 22 from the filter wall 3 to the discharge point 19. Ice pressure occurring in the interior 15 of the filter cartridge 1 can be dissipated via the bypass opening 10 of the filter cartridge 1 to the outside or into the cartridge receptacle 28. A compressible insert 27 is provided in the cartridge receptacle 28.It is possible that the compressible insert 27 is a component of the filter cartridge 1, in which case particular reference is made to the . Fig. 5 and the explanations thereto. However, it is also possible that the compressible insert 27 is positioned as a separate component in the conveying device 2 or in the cartridge receptacle 28. The filter cartridge 1 is connected to the conveying device 2 via a drain opening 8 and a coupling device 9. In the Fig. 7 also shows that a heater 30 of the conveying device 2 extends through the outlet opening 8 into the interior of the filter cartridge 1. The heater 30 can also simultaneously be a heat-conducting structure, which dissipates heat from the interior when the heater 30 is not in operation. Since the heater 30 protrudes from above into the filter cartridge 1, it can be ensured that the interior freezes first at the top and the ice pressure builds up towards the bypass opening last. Fig. 6 also shows the freezing direction 6 in which ice formation can occur in the conveying device 2 in the area of ​​the filter cartridge 1.

[0043] Fig.Figure 8 shows a motor vehicle 23 having an internal combustion engine 24 and an exhaust gas treatment device 25 for purifying the exhaust gases of the internal combustion engine 24. Reducing agent can be conveyed from a tank 26 into the exhaust gas treatment device 25 using a conveying device 2. The exhaust gas treatment device can then contain, for example, an SCR catalyst that converts the exhaust gases according to the SCR process. List of reference symbols 1 filter cartridge 2 Conveyor device 3 filter wall 4 retaining wall 5 upper edge area 6 Freezing direction 7 axis of symmetry 8 Drain opening 9 Coupling device 10 Bypass opening 11 first diameter 12 second diameter 13 Sieve element 14 Basic form 15 Interior 16 Top 17 Subpage 18 intake point 19 Drop-off point 20 Conveyor path 21 first section 22 second section 23 Motor vehicle 24 internal combustion engine 25 Exhaust gas treatment system 26 tanks 27 compressible insert 28 cartridge holder 29 Wave structure 30 Heating 31 paragraph 32 recordings 33 lower edge area

Claims

[1] Filter cartridge (1) for a conveying device (2) for a reducing agent, comprising at least one filter wall (3) and at least one supporting wall (4) which together with the filter wall (3) forms an interior space (15), wherein the at least one supporting wall (4) has a drain opening (8) and a bypass opening (10), wherein the drain opening (8) can be coupled to the conveying device (2) and the bypass opening (10) forms a bypass to the filter wall (3) and the reducing agent is a urea-water solution. [2] Filter cartridge (1) according to claim 1, characterized by that the bypass opening (10) has a second diameter (12) which is less than one tenth of a first diameter (11) of the drain opening (8). [3] Filter cartridge (1) according to one of the preceding claims, characterized by that the bypass opening (10) is covered by a sieve element (13). [4] Filter cartridge (1) according to claim 3, characterized bythat the sieve element (13) is welded or vulcanized onto the supporting wall (4). [5] Filter cartridge (1) according to one of the preceding claims, characterized by that the bypass opening (10) has a second diameter (12) which is at least 100 µm [micrometers]. [6] Filter cartridge (1) according to one of the preceding claims, characterized by that the filter wall (3) forms a cylindrical basic shape (14) and wherein an upper side (16) and a lower side (17) are each formed by a supporting wall (4), wherein the drain opening (8) is arranged on the upper side (16) and the bypass opening (10) is arranged on the lower side (17). [7] Filter cartridge (1) according to one of the preceding claims, characterized by that the supporting wall (4) has a receptacle (32) in which a compressible insert (27) is arranged. [8] Conveying device (2) for a reducing agent, comprising a suction point (18) and a discharge point (19), wherein a conveying path (20) for the reducing agent is formed from the suction point (18) to the discharge point (19), which conveying path runs at least through a filter cartridge (1) according to one of the preceding claims. [9] Motor vehicle (23) comprising an internal combustion engine (24), an exhaust gas treatment device (25) for cleaning the exhaust gases of the internal combustion engine (24) and a conveying device (2) according to claim 8 for conveying reducing agent into the exhaust gas treatment device (25).

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