Supply module for the delivery of an operating / auxiliary material

Abstract

Supply module (10) for conveying an operating / auxiliary material from a storage tank (36) of an exhaust aftertreatment system with a carrier body (18) on which a conveying unit (16) and a filter (12) are mounted, characterized in that a heating element (50) has at least one electrical conductor (62) with cross-sectional areas (64, 66) that differ depending on the installation position.

Description

State of the art

[0001] The invention relates to a supply module for conveying an operating / auxiliary material of an exhaust aftertreatment system with a carrier body on which a conveying unit and filter are mounted.

[0002] DE 10 2013 217 333 A1 relates to an in-tank filter and a suitable filter medium. The in-tank filter serves to filter a liquid and has a first filter side and a second filter side. A receiving chamber is arranged between these, and filtered liquid can be drained from the receiving chamber via a connection. An annular circumferential wall is provided to form a housing, enclosing the first and second filter sides, with at least one filter side having a pleated filter medium. DE 10 2010 062 982 A1 discloses a tank installation module with a heating element with a plastic casing. DE 10 2009 035 940 A1 shows an SCR exhaust aftertreatment device with several metering units. DE 20 2007 006 636 U1 describes a liquid container with a metallic resistance heating element.

[0003] In exhaust aftertreatment systems, a supply module can be used in which the filter is located at the bottom of the module. The filter is connected via a channel to an intake point of a pumping unit and is bonded to the module's support structure at several ribs. The filter's function is to remove dirt and any additional contaminants that may enter the operating / auxiliary fuel tank during refueling, thus protecting sensitive components such as the pump and the metering module. The primary source of dirt accumulation in the filter over its service life is dirt introduced into the storage tank during refueling. Since the filter is designed to last its entire service life, its capacity must be correspondingly high.

[0004] DE 10 2013 222 288 A1 relates to a supply module for conveying an operating / auxiliary fluid. The supply module serves to convey an operating / auxiliary fluid to an exhaust aftertreatment system and has a support structure on which a conveying unit and a filter are mounted. The filter forms a holder for a heater that essentially encloses it. The filter body comprises a first and a second housing half. The heater, which essentially encloses the filter, comprises a number of heating wire windings.

[0005] According to the solution in DE 10 2013 222 288 A1, a resistance heater with a constant heating wire cross-section is located around the filter. A number of heating wire turns are wound around the filter. The heater's function is to thaw the operating / auxiliary fluid, which is primarily a freezing-capable reducing medium, and the surrounding tank volume, while it is frozen within the filter. To save costs and ensure efficient heating performance, the filter housing forms the support structure for the heating wire turns. Due to the described requirements for the filter and the heating wire, which, by design, has a length of more than 3 m, the operating conditions of the filter / heater combination depend on the fill level of the operating / auxiliary fluid in the storage tank and are characterized by varying degrees of wetting of the heating wire turns.Operating conditions can range from "completely covered with liquid" to "covered with liquid only in the area near the support" to "completely exposed," depending on the fill level of the operating fluid / auxiliary material in the reservoir. If the filter, and thus the heating wire windings of the heater, are only partially wetted by the operating fluid / auxiliary material, the exposed heating wire areas experience a significant temperature increase. To prevent damage to the filter and support components due to excessively high temperatures, the heating power is reduced. However, this reduction in heating power leads to a deterioration of the defrosting performance under these operating conditions.In the solution according to DE 10 2013 222 288 A1, the heating wire is connected and sealed to the carrier body of the supply module by means of a sleeve which is adapted to the material of the carrier part, thus with various electrical contacts and, in particular, sealing elements designed as O-rings. Description of the invention

[0006] According to the invention, a supply module for conveying an operating / auxiliary material of an exhaust aftertreatment system is proposed, which includes a heating element having at least one electrical conductor with cross-sectional areas that differ depending on the installation position of the heating element.

[0007] In an advantageous further development of the solution proposed according to the invention, the supply module comprises a heating element, which may be a stamped grid, at least one heating wire, or more generally, at least one electrical conductor. The at least one electrical conductor can be a conductor track or one or more heating wires.

[0008] The heating element proposed according to the invention for the supply module for conveying an operating / auxiliary material is designed in the form of a cage and comprises at least one side surface and one bottom surface. The cage shape of the heating element proposed according to the invention is complementary to the geometry of a filter body that is mounted on the top of the support body.

[0009] The supply module proposed according to the invention comprises the heating element, which is designed such that it exhibits a locally reduced resistance in unwetted areas exposed when the operating / auxiliary fluid level in the storage tank is low. This results in a local reduction in the heating power or area power of the heating element. This is achieved, for example, by the fact that the at least one electrical conductor of the heating element has an increased cross-sectional area in the unwetted areas.

[0010] In the wetted areas of the heating element, which is mounted on the support body and located near the bottom of the storage tank, the at least one electrical conductor of the heating element exhibits increased electrical resistance. In these areas, the at least one electrical conductor of the heating element has a second cross-sectional area that is smaller than the first cross-sectional area of ​​the at least one electrical conductor. This advantageously allows for an adaptation of the cross-sectional area of ​​the at least one electrical conductor for the wetted areas, i.e., those that are always surrounded by a volume of liquid, thus achieving optimal heating performance. This enables a physically favorable heat input, i.e., intensive heating of the object to be defrosted, for example, the filter, through efficient heat transfer from the underside of the filter.

[0011] The heating element, which has at least one electrical conductor, for example a conductor track, a stamped grid, or one or more heating wires, is advantageously encased in a plastic overmolding forming a closed surface. The plastic material is advantageously, for example, HDPE, i.e., the same material from which the carrier body of a supply module is also made. By overmolding the heating element with plastic, its surface area is increased, thereby improving heat transfer to the medium to be heated, i.e., the operating / auxiliary material stored in the reservoir. Alternatively, instead of overmolding the heating element with plastic, it can be potted or wrapped with insulation.

[0012] The heating element, preferably cage-shaped and complementary to the geometry of a filter in the supply module, can have 180° bends in the areas defined by a first enlarged cross-sectional area. These 180° bends can, for example, be formed as flattened, widened sections of the heating element's at least one electrical conductor. The heating element, surrounded by the plastic overmolding, can be plugged into a socket on the top of the carrier body and thus electrically connected.If the material used for the plastic overmolding of the heating element is identical to the material used for the carrier body, a material-bonded connection between the plastic overmolding of the heating element and the carrier body can advantageously be achieved. This significantly simplifies the electrical contact compared to the prior art solution, which requires numerous small parts and sealing elements. While the heating element is secured by the material-bonded connection between the carrier body and the plastic overmolding of the heating element, electrical contact is established via the at least one electrical conductor at its ends in the socket located on the top of the carrier body.

[0013] The electrical contacts are represented by the open ends of the at least one electrical conductor. If the plastic overmolding of the heating element and the material of the carrier body are different material pairings, which may be due, for example, to increased insulation requirements of the heating element, a sealing element must be used.

[0014] The supply module proposed according to the invention is used in particular in an exhaust aftertreatment system in which the supply module provides heating and metering of an operating / auxiliary substance into an exhaust tract of an internal combustion engine. Advantages of the invention

[0015] The solution proposed according to the invention advantageously ensures that a supply module for conveying a freezing-capable operating / auxiliary material, such as a reducing agent for exhaust gas aftertreatment, is protected from reaching critical, i.e., excessively high, component temperatures in exposed areas. Furthermore, the solution proposed according to the invention allows the entire available electrical power to be utilized during heating operation, preventing the heating element from having to be switched off due to excessively high component temperatures in unwetted areas. The solution proposed according to the invention allows the heating element to operate at optimized heating power by increasing the temperature in the relevant area, i.e., where it is ensured that the medium to be heated or defrosted, in this case the operating / auxiliary material, is always present.The increased surface area achievable through plastic overmolding allows the operating temperatures of the heating element to be kept lower compared to state-of-the-art solutions. Because a socket-like connection can be established between the carrier body and the heating element at a joint, the simplified contacting and joining concept results in a reduction in component size; furthermore, the assembly steps required for mounting the heating element can be drastically reduced.

[0016] The invention makes it possible to create areas with different power densities, thus enabling the implementation of advanced heating strategies. For example, the solution proposed according to the invention allows for the creation of multiple heating circuits with varying power outputs. These heating circuits can be controlled by sensors, such as temperature sensors. By locally adjusting the power density, for example, by locally increasing it, the heating energy can be generated as needed in critical areas, such as the filter's suction channel, resulting in improved defrosting performance overall. Regarding the configuration of the heating element, its shape can be selected to minimize thermally induced mechanical stresses in the plastic material, which also applies to the heating element material. For example, a meandering design of the heating element can be achieved.To save on components and reduce the installation space required, the heating element can be integrated into a carrier body located on the underside of a storage tank. Brief description of the drawing

[0017] The invention is described in more detail below with reference to the drawing.

[0018] It shows: Fig. 1 a supply module with pumping unit and filter, connected to a storage tank, in particular located in the area of ​​the tank bottom, Fig. 2. The at least one electrical conductor is pre-bent into the cage shape of the heating element. Fig. 3 the at least one electrical conductor provided with a plastic overmolding as shown in Fig. 2, Fig. 4 a schematic representation of the joint between the heating element and the carrier body of the supply module and Fig. 5 a perspective top view of the supply module, in which a filter housing of the filter is enclosed by a heating element with a plastic overmolding.

[0019] Fig. Figure 1 shows a supply module with pump unit and filter flanged to the bottom of a storage tank.

[0020] From the representation according to Fig. Figure 1 shows a supply module 10, which includes a filter 12. The filter is shown in the diagram according to Fig. The filter 12 is surrounded by a heater 14, which comprises individual heating wire windings 20 wound side by side around the filter 12. The supply module 10 comprises a substantially disc-shaped support body 18 on which a conveying unit 16 is located. A medium purified by the filter 12, in particular an operating / auxiliary material stored in a storage tank 36, especially a freezeable reducing agent such as urea or a urea-water solution, is conveyed via this conveying unit 16. The conveying unit 16 and the filter 12 are mounted on a top surface 22 of the support body 18. The support body 18 is preferably an injection-molded plastic part made of a plastic material such as HDPE. An electrical connection 24 is located on the top surface 22 of the support body 18, through which the heater 14 of the supply module 10 is electrically connected. A flange 26 is located on the underside of the support body 18.The flange 26 includes a hydraulic connection 28 and at least one electrical connector 30. A line extends from the hydraulic connection 28 to a [missing information]. Fig. 1. Dosing module of the exhaust aftertreatment system (not shown). The operating / auxiliary fluid, which has passed through the filter 12 from the storage tank 36 via the pumping unit 16, is fed to the dosing module and then into the exhaust tract of the internal combustion engine to reduce NOₓ contained in the exhaust gas. x -Ingredients added in measured doses.

[0021] The supply module 10 is electrically connected to a power supply 88 via at least one electrical connector 30 (compare illustration according to Fig. 5) connected.

[0022] The storage tank 36 includes a connection flange 32 provided on the tank bottom 34, with which the supply module 10 is connected to the storage tank 36.

[0023] From the representation according to Fig. 1 further indicates that there is a liquid supply in the storage tank 36, the fill level of which is indicated by reference numeral 38. Fig. Figure 1 further shows that the heater 14, which in this case is wound around the filter 12 with a number of heating wire turns 20, forms unwetted areas 42 above the fill level 38 and a wetted area 40 immersed in the liquid reservoir. At full heating power, unacceptably high temperatures can occur in the unwetted area 42, which can lead to damage to the heater 14. Design variants

[0024] Fig. Figure 2 shows a heating element which is formed in a cage shape and includes a multiply bent electrical conductor.

[0025] From the representation according to Fig. Figure 2 shows that a heating element 50, which may be a stamped grid, an electrical conductor 62, or at least one heating wire, assumes a cage shape 52. The at least one electrical conductor 62 is bent such that it forms a first side surface 54, a second side surface 56 opposite it, and a bottom surface 58. Electrical contact 60 is provided by the ends 90 and 92 of the electrical conductor 62. Fig. Figure 2 shows that the at least one electrical conductor 62 has different cross-sectional areas 64, 66. For example, the at least one electrical conductor 62 assumes a second reduced cross-sectional area 66 in the base area or in the area of ​​90° bends 70, while the at least one electrical conductor 62 has a first increased cross-sectional area 64 in the upper area of ​​the two side surfaces 54, 56 in the area of ​​180° bends 68. From the perspective view of the heating element 50 according to the illustration in Fig. 2 shows that the at least one electrical conductor 62 has a greater width in the area of ​​the 180° bends 68 compared to the elongated sections of the at least one electrical conductor 62. The in Fig. The heating element shown in Figure 2 is bent from an electrical conductor 62 and transformed into the cage shape 52.

[0026] From the representation according to Fig. 2. It follows that the heating element 50 has a higher electrical resistance in the upper areas of the side surfaces 54, 56 due to the increased cross-sectional area 64 of the at least one electrical conductor 62. In these areas of the heating element 50, this prevents the heating element from reaching impermissibly high operating temperatures, which could be critical for the component, provided that these areas of the heating element 50 are not wetted by a heat-absorbing medium, such as the operating / auxiliary material stored in the reservoir 36.

[0027] Instead of the in Fig. The heating element 50 could also be formed by several heating wires running parallel to each other in the electrical conductor 62 shown here, designed as a conductor track; it is also possible to design the heating element 50 as a stamped grid.

[0028] Fig. Figure 3 shows the heating element, which is surrounded by a plastic overmolding.

[0029] From the representation according to Fig. 3 shows that the in Fig. The heating element 50, which has the cage shape 52 shown in Figure 2, is provided with a plastic overmolding 72. The plastic overmolding 72 creates closed surfaces 74 in the area of ​​the side surfaces 54, 56 and in the area of ​​the bottom surface 58, which ensure a uniform heat input when the heating element 50 is electrically connected. This is particularly relevant if the heating element 50, provided with the plastic overmolding 72, is mounted on the filter 12 as shown in Figure 2. Fig. When the filter 12 is mounted, uniform heating of the filter 12 can be achieved. A particularly advantageous feature is the overmolding 72 made of a plastic material identical to that of the carrier body 18 of the supply module 10. This facilitates easier mechanical joining of the two plastic materials during assembly. Ideally, the plastic materials of both components are joined by a material bond.

[0030] Fig. Figure 3 shows that the at least one electrical conductor 62 of the heating element 50, in its finished overmolded state, comprises a connector part 76 in the region of ends 90 and 92. The connector part 76, in which the ends 90 and 92 of the at least one electrical conductor 62 are embedded, enables a mechanically robust joining of the heating element 50 during mounting on the top surface 22 of the carrier body 18 made of plastic material. The 90° bends 70 of the heating element 50, which is provided with the plastic overmolding 72, are also uniformly enclosed with a plastic material film.

[0031] Fig. Figure 4 shows an electrical and a mechanical connection between the heating element and the carrier body.

[0032] From the representation according to Fig. Figure 4 shows that the ends 90, 92 of the at least one electrical conductor 62, which are free from the plastic overmolding 72, are inserted into electrical terminals of the carrier body 18 in the manner of a socket. From the electrical contacts embedded in the top 22 of the carrier body 18 for the mating contact of the heating element 50, a Fig. 4 indicated wiring harness 80. As from Fig. As can be seen from Figure 4, the ends 90 and 92 of the at least one electrical conductor 62 of the heating element 50 are - see also the illustration according to Figure 4. Fig. 3 - enclosed by a plug part 76, which is part of the plastic overmolding 72. At a connection point 78, the plug part 76 of the heating element 50 is joined to the top of the carrier body 18 by a material bond. The material bond, produced, for example, by a plastic welding process, provides effective fixation of the heating element 50 to the top 22 of the carrier body 18, while the electrical connection requires no O-rings for sealing and no further sleeve-shaped small parts for guiding the electrical contact 60, and is provided by the ends 90 and 92 of the at least one conductor 62, which are inserted into a type of socket on the top of the carrier body 18. In the illustration according to Fig. 4 are filter body halves 84, 86 of one in Fig. 5 indicated in perspective view of the filter body 82.

[0033] The material-bonded connection between the heating element 50, which is provided with the plastic overmolding 72, and the carrier body 18, which is also made of HDPE material, eliminates the need for small parts, in particular O-rings, which are used as sealing elements in other solutions according to the prior art.

[0034] The perspective top view according to Fig. 5 is a supply module whose filter is surrounded by the heating element.

[0035] From the representation according to Fig. From section 5, it follows that the carrier body 18, in addition to the conveying unit 16, has the filter 12. The filter 12 comprises a filter body 82, which is located in the Fig. In the embodiment shown in Figure 5, a first filter body half 84 and a second filter body half 86 are included. The filter body 82 of the filter 12 is shown in the perspective view according to Fig. 5 surrounded by the heating element 50 formed in cage shape 52. Fig. Figure 5 shows that the side surface of the second filter body half 86 is covered by the closed surface 74, or the plastic overmolding 72, of the heating element 50. The two ends 90 and 92 of the electrical conductor 62 converge in the molded-on connector part 76, which is part of the plastic overmolding 72 of the heating element 50. An electrical connection for a power supply 88 is visible on the top surface 22 of the carrier body 22. The connector part 76 of the plastic overmolding 72 of the heating element 50 is inserted into a socket 94 for electrical contact, which is located on the top surface 22 of the carrier body 18, molded from HDPE plastic. On the underside of the plastic carrier body 18 is the flange 26, which includes a hydraulic connection 28 extending to the metering module of the exhaust aftertreatment system in the exhaust tract of the internal combustion engine.In addition, the flange 26, located on the underside of the support body 18, has further electrical connectors 30. The [information] is based on the... Fig. 1, Fig. 2, Fig. 3, Fig. 4 to Fig.The solution proposed in Figure 5 according to the invention enables the realization of a resistance heater. Instead of a heating element with constant resistance over its entire length, the invention proposes a heating element 50 which has a changing resistance depending on its installation position. The locally required decrease or increase in resistance is achieved by changing the cross-sectional areas 64, 66 of the at least one current-carrying electrical conductor 62. Alternatively, a stamped grid with grid bars of varying widths can be used instead of the at least one electrical conductor 62. Furthermore, it is also possible to use several heating wires with different diameters arranged in series.In the heating element 50 proposed according to the invention, the local resistance in the unwetted areas 42, which are exposed to air at low fill levels 38 in the storage tank 36, is reduced. The maximum temperature generated in these areas is thereby limited to a permissible level. The cross-sections of the at least one conductor located below the fill level 38 can be adapted to achieve optimal heat output.

[0036] The solution proposed according to the invention allows for the realization of multiple heating circuits that can be operated with different power densities or heating outputs, thus enabling the implementation of advanced heating strategies. Independent control of the heating circuits is possible, preferably by means of sensors, ideally temperature sensors. Furthermore, the heating element, which comprises at least one electrical conductor, can be integrated into the plastic carrier part of the power supply module. The power output of the heating element proposed according to the invention can be adjusted as needed, so that locally increased and locally decreased heating outputs can be achieved with one and the same heating element at different localized points or areas.

[0037] The invention is not limited to the embodiments described here and the aspects highlighted therein. Rather, within the scope specified by the claims, a multitude of modifications are possible, which fall within the bounds of skilled craftsmanship.

Claims

[1] Supply module (10) for conveying an operating / auxiliary material from a storage tank (36) of an exhaust aftertreatment system with a carrier body (18) on which a conveying unit (16) and a filter (12) are mounted, characterized by , that a heating element (50) has at least one electrical conductor (62) with cross-sectional areas (64, 66) that differ depending on the installation position. [2] Supply module according to claim 1, characterized by that the heating element (50) is designed as a stamped grid, as at least one heating wire or as at least one electrical conductor (62). [3] Supply module according to any one of the preceding claims, characterized by , that the heating element (50) is designed in cage form (52), comprising at least one side surface (54, 56) and a bottom surface (58). [4] Supply module according to claim 3, characterized by, that the cage shape (52) of the heating element (50) is complementary to the geometry of a filter body (82) of the filter (12). [5] Supply module according to any one of the preceding claims, characterized by , that the heating element (50) in unwetted areas (42) which are exposed at low fill levels (38) in the storage tank (36) exhibits a locally reduced resistance to represent a locally reduced heating power. [6] Supply module according to the preceding claim, characterized by , that the at least one electrical conductor (62) of the heating element (50) has a first enlarged cross-sectional area (64) in the unwetted areas (42). [7] Supply module according to any one of the preceding claims, characterized by , that the heating element (50) in the wetted areas (40) near a tank bottom (34) of the storage tank (36) has an increased electrical resistance to achieve a locally increased heating power. [8] Supply module according to the preceding claim, characterized by , that the at least one electrical conductor (62) of the heating element (50) in the wetted areas (40) has a second, reduced cross-sectional area (66) which is reduced in relation to the first enlarged cross-sectional area (64). [9] Supply module according to any one of the preceding claims, characterized by , that the heating element (50) is provided with a plastic overmolding (72) forming closed surfaces (74). [10] Supply module according to claim 6, characterized by , that the first enlarged cross-sectional area (64) in the at least one electrical conductor (62) of the heating element (50) is designed as a 180° bend (68). [11] Supply module according to any one of the preceding claims, characterized by, that the heating element (50) is electrically contacted on a top side (22) of the carrier body (18) in a socket (94) with ends (90, 92) of the at least one electrical conductor (62). [12] Use of the supply module (10) according to any one of claims 1 to 11 for conveying and metering a freezeable operating / auxiliary substance into an exhaust aftertreatment system of an internal combustion engine.

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