APPARATUS FOR CONTROLLING THE TEMPERATURE OF A FREEZABLE OPERATING/AUXILIARY MEDIUM

Abstract

The invention relates to an apparatus for controlling the temperature of a freezable operating/auxiliary medium (12) which is stored in a reservoir (10) and is used for exhaust gas aftertreatment in compression ignition engines. An overmolding (22) on a heating element (56) forms a wall (50) of an intake duct (28) within a covering area (58).

Claims

1. An apparatus for controlling the temperature of a freezable operating/auxiliary medium (12) stored in a storage tank (10) for exhaust gas posttreatment in compression internal combustion engines, the apparatus comprising an intake duct wall (50) of an intake duct (28) formed by an extrusion coating (22) of a heating element (56) within an overlap region (58).

2. The apparatus for controlling the temperature as claimed in claim 1, characterized in that the intake duct (28) is delimited by the extrusion coating (22) of the heating element (56) and by a filter (14) or a carrier (16).

3. The apparatus for controlling the temperature as claimed in claim 1, characterized in that the extrusion coating (22) of the heating element (56) has a reduced wall thickness (52) in the overlap region (58).

4. The apparatus for controlling the temperature as claimed in claim 1, characterized in that a thermal resistance between the heating element (56) and the intake duct (28) is only provided by the thermal resistance (70) of the extrusion coating (22) of the heating element (56).

5. The apparatus for controlling the temperature as claimed in claim 1, characterized in that the heating element (56) enclosed by the extrusion coating (22) replaces a filter cover (26).

6. The apparatus for controlling the temperature as claimed in claim 1, characterized in that a filter nonwoven material (18), which is wetted on an upper side (66) and on a lower side (68) by operating/auxiliary medium (12), is accommodated in the intake region (72) of the intake duct (28).

7. The apparatus for controlling the temperature as claimed in claim 1, characterized in that the heating element (56) having extrusion coating (22) overlaps both the intake duct (28) and also the intake region (72) located in front of the intake duct (28) in the storage tank (10).

8. The apparatus for controlling the temperature as claimed in claim 1, characterized in that a first materially-bonded joint (74) is embodied as a circumferential weld seam between the heating element 56 or the extrusion coating 22 and further components of the storage tank (10).

9. The apparatus for controlling the temperature as claimed in claim 3, characterized in that the reduced wall thickness (52) of the extrusion coating (22) within the overlap region (58) is between 1 mm and 2 mm and the intake duct (28) extends essentially along a flat heating element (56).

10. (canceled)

11. A method for thawing a freezable operating/auxiliary medium (12) in an exhaust gas posttreatment system of compression internal combustion engines, the method comprising using the apparatus as claimed in claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The invention is described in greater detail hereinafter on the basis of the drawings.

[0019] In the figures:

[0020] FIG. 1 shows a configuration of a heater and an intake duct,

[0021] FIG. 2 shows the thermal resistances resulting from this arrangement,

[0022] FIG. 3 shows a top view of an apparatus, wherein the heating element designed in a flat construction is not shown,

[0023] FIG. 4 shows a section through the apparatus according to FIG. 3 along section line IV-IV shown in FIG. 3, and

[0024] FIG. 5 shows the thermal resistance resulting in the proposed solution between the temperature of the heating unit and the temperature of the intake duct.

DETAILED DESCRIPTION

[0025] A storage tank 10, in which a freezable operating/auxiliary medium 12, which is preferably a reducing agent, is accommodated, is apparent in the illustration according to FIG. 1. The freezable operating/auxiliary medium freezes at a temperature of less than 11 C. As FIG. 1 shows, a filter 14 is connected upstream of an intake duct 28. The filter 14 can be accommodated on a carrier 16 and can comprise a filter nonwoven material 18. A heating element/cooling element 20, which is enclosed by an extrusion coating 22, which is generally made of a plastic material, is located above the filter 14. In addition, a heat conduction pin 24, which is made of stainless steel, for example, is located in a filter cover 26. A conveyor assembly feed 30 extends out from the intake duct 28 to a conveyor assembly (not shown in FIG. 1).

[0026] In the solution according to FIG. 1, the thermal resistances illustrated in FIG. 2 result. As is apparent from the schematic illustration according to FIG. 2, a first thermal resistance 38 of the extrusion coating and a second thermal resistance 40 exist between the Theater, 36 and the temperature 48, TunaIce duct, prevailing in the intake duct, wherein the second thermal resistance 40 is particularly critical, since it is defined in the best case by the operating/auxiliary medium and in the worst case at low fill levels by air. The second thermal resistance 40 thus rises significantly. In addition, dynamic influences, for example, the movement of the operating/auxiliary material (sloshing movements) can come to bear, which represent a continuous energy loss due to flowing away of the heated operating/auxiliary medium. Furthermore, a further thermal resistance 42 is given by the heat conduction pin 24. Finally, a second thermal resistance 46 exists, also caused by the extrusion coating 22, and also a thermal resistance 46 which is caused by the presence of the filter cover 26.

Embodiment Variants

[0027] FIG. 3 shows a partial view of an apparatus proposed according to the invention for controlling the temperature of a freezable operating/auxiliary medium 12 stored in a storage tank 10. In the top view according to FIG. 3, a heating element 56 embodied essentially in a flat construction, which overlaps the components illustrated in FIG. 3, is not shown. It is apparent from the top view according to FIG. 3 that the filter nonwoven material 18, enclosed by a filter edge 54, extends in a crescent shape in front of the intake duct 28 in the intake region 72 (cf. illustration according to FIG. 4). The conveyor assembly feed 30 extends from the intake duct 28 perpendicularly to the plane of the drawing according to FIG. 3. Reference numerals 74 and 76 respectively identify first and second materially bonded joints, which are used as connection points 62, 64, cf. FIG. 4, between the actual heating element 56 in flat construction or its extrusion coating 22 and the further components of the storage tank.

[0028] FIG. 4 shows a section through the apparatus proposed according to the invention along section line Iv-Iv shown in FIG. 3.

[0029] As is apparent from the section according to FIG. 4, the heating element 56 designed in flat construction is enclosed by an extrusion coating 22, which is generally made of plastic material. The extrusion coating 22 has multiple functions. On the one hand, the extrusion coating 22 of the heating element 56 designed in flat construction is used for encasing and protecting the heating element 56 against the medium surrounding it, i.e., the freezable operating/auxiliary medium 12. As is apparent from FIG. 4, the heating element 56 designed in flat construction and enclosed by the extrusion coating 22 is fastened at connection points 62, 64, which are embodied as materially bonded joints 74, 76, above the intake duct 28 and above the filter nonwoven material 18. The heating element 56 designed in flat construction is provided here such that the heating element 56 or the extrusion coating 22 extends along an overlap region 58 along the intake duct 28. It is apparent from FIG. 4 that a part of the extrusion coating 22 of the heating element 56 designed in flat construction is used as an intake duct wall 50. To minimize its thermal resistance 70 as much as possible, the extrusion coating 22 can be embodied in a reduced wall thickness 52 in the region in which the intake duct wall of the intake duct 28 is formed. The resulting thermal resistance 70 during the heat transfer from the heating element 56 to the frozen operating/auxiliary medium 12 collected in the intake duct 28 will thus be reduced still further. The geometry of the extrusion coating or the heating element is furthermore provided such that it also overlaps an intake region 72. The intake region 72, via which the operating/auxiliary medium 12 stored in the tank flows to the filter nonwoven material 18, is located on its upper side 66. As is apparent from the section according to FIG. 4, the filter nonwoven material 18, stabilized by the filter edge 54, is wetted from its upper side 66 and also its lower side 68. Due to the selected geometry of the heating element 56 designed in flat construction and the extrusion coating 22 surrounding it, the intake region 72, which is upstream of the intake duct 28 in the storage tank, can also be heated.

[0030] An inflow curve formed in the intake duct 28 is identified by reference numeral 60, which extends from the filter nonwoven material 18 to the section of the intake duct 28, within which the extrusion coating 22 of the heating element 56 designed in flat construction creates the intake duct wall 50. The length of this section corresponds to the overlap region 58.

[0031] FIG. 5 shows a thermal equivalent circuit diagram, according to which only the thermal resistance 70 of the extrusion coating 22 is to be overcome between Theater 36 of the heating element 56 designed in flat construction and the intake duct temperature 48. This resistance is clearly minimized in comparison to the solution shown in FIG. 2, as a comparison to the illustration according to FIG. 2 shows, so that the thawing speed of the apparatus proposed according to the invention is significantly shorter, as described above.

[0032] The solution proposed according to the invention is distinguished by an avoidance of uncontrollable thermal resistances, as can be induced, for example, due to sloshing movements of the operating/auxiliary medium or by air. According to the solution proposed according to the invention, all thermal resistances are given by solid body contact and are therefore well-defined.

[0033] The invention is not restricted to the exemplary embodiments described here and the aspects highlighted therein. Rather, a variety of modifications is possible within the scope specified by the claims, which are in the scope of routine measures in the art.