Liquid tank including integrated surface structure

Abstract

A liquid tank includes a tank wall enclosing a tank volume and at least one relief structure facing the tank volume on an inner side of the tank wall. The relief structure is formed as one-piece with the tank wall. Two shell parts can be joined along a joining surface to make a section of the tank wall. One of the shell parts can include a tank bottom. At least one part of the relief structure can be formed on the tank bottom. The relief structure can include projections protruding into the tank volume along a local direction of projection.

Claims

1. A liquid tank comprising: a tank wall enclosing a tank volume; and at least one relief structure facing the tank volume on an inner side of the tank wall; wherein the at least one relief structure is formed as one-piece with the tank wall, wherein at least two shell parts are joined along a joining surface to make a section of the tank wall, wherein at least one of the shell parts comprises a tank bottom, wherein at least one part of the at least one relief structure is formed on the tank bottom, wherein the at least one relief structure comprises projections protruding into the tank volume along a local direction of projection, said projections being arranged orthogonally to their direction of projection with spacing between them, wherein said projections extend towards said joining surface, and wherein an average distance between two immediately adjacent projections is not less than one-third and not more than five times an average thickness of the two projections.

2. The liquid tank according to claim 1, wherein at least one exposed inner layer of the tank wall facing the tank volume is made, at least in a section including the at least one relief structure, of a castable material.

3. The liquid tank according to claim 2, wherein the tank wall throughout its entire thickness is made, at least in said section of the tank wall including the at least one relief structure, of a castable material.

4. The liquid tank according to claim 2, wherein the castable material is thermoplastic.

5. The liquid tank according to claim 1, wherein the liquid tank is designed and intended configured to contain aqueous urea solution.

6. The liquid tank according to claim 1, wherein the at least two shell parts are joined to make the liquid tank.

7. A method of fabricating the liquid tank according to claim 1, comprising the following steps: providing of a castable mass, and casting the mass to make the section of the tank wall, said tank wall comprising the tank bottom including the at least one relief structure facing the tank volume of the liquid tank that is to be fabricated.

8. The method according to claim 7, wherein the casting step comprises a molding method.

9. The method according to claim 8, wherein the casting step comprises an injection molding method.

10. The method according to claim 7, wherein the method comprises casting the at least two shell parts and joining the at least two shell parts.

Description

BRIEF DESCRIPTION OF THE DRAWING FIGURES

(1) The present invention will be explained below based on the accompanying drawings. The drawing designated as FIG. 1 shows a roughly schematic, longitudinal-section view through an inventive embodiment of a liquid tank.

(2) In FIG. 1 an inventive liquid tank is generally designated with 10. The liquid tank 10 preferably comprises an upper shell part 12, which includes a filling opening 14 including a flanged rim 16 surrounding the filling opening 14. A filling line, for example, a filling pipe not shown in FIG. 1, can be connected to the flanged rim 16.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(3) The liquid tank 10 also comprises a lower shell part 18 that includes a withdrawal opening 20 including a flanged rim 22 surrounding the withdrawal opening 20. A withdrawal line not shown in FIG. 1 can in turn be connected to the flanged rim 22.

(4) The upper shell part 12 and the lower shell part 18 are preferably joined to each other, for example glued or welded, along a respective circumferential joining flange 24 or 26. The joining flanges 24 and 26 come into contact with each other along a joining surface 28, which is preferably flat.

(5) The tank 10 includes a tank wall 30 that surrounds a tank volume 32 of the tank 10. The tank wall 30 is formed, on the one hand, by the wall 34 of the upper shell part 12, and is formed on the other hand by the wall 36 of the lower shell part 18.

(6) An inner side 30a of the tank wall 30 forms a boundary surface of the tank wall with respect to the tank volume 32. The inner side 30a is in turn formed, on the one hand by the inner side 34a of the wall 34 of the upper shell part 12, and is formed on the other hand by the inner surface 36a of the wall 36 of the lower shell part 18.

(7) The liquid tank 10 can of course, deviating from the example shown, include more than two shell parts, or it can also be formed one-piece, for example by blow molding.

(8) In a bottom section 38 of the tank 10, more precisely the lower shell part 18, a relief structure 40 is formed on the inner side 30a or inner surface 36a facing the tank volume 32. The relief structure 40 is formed as one-piece in a materially continuous manner with the tank 10, in particular with the lower shell part 18.

(9) The lower shell part 18like the upper shell part 12is preferably manufactured by injection molding.

(10) In the example shown, the relief structure 40 formed at the same time as the injection molding of the lower shell part 18 includes similar projections 42 which protrude from the bottom section 38 of the lower shell part 18 along a direction of projection V into the tank volume 32. In the example shown, the projections 42 extend, independently of their location, at substantially uniform height, parallel to one another, in a direction of extension that is orthogonal to the drawing plane of FIG. 1. For example, the projections 42 can also extend a short distance away on the lateral wall 44 to the joining surface 28.

(11) Immediately adjacent projections 42 are disposed spaced from one another by spacings 46 in a direction orthogonal both to the direction of projection V and to the direction of extension of the projections 42. In FIG. 1, the direction of spacing is parallel to the drawing plane.

(12) All projections 42 in the example shown are preferably identical, as are the spacings 46 between the adjacent projections 42.

(13) In the example shown, the spacings 46 are slightly larger than the thicknesses of the projections 42, which thicknesses are to be measured in the same direction. The spacings 46 are dimensioned such that they are too large for the formation of capillary effects between mutually facing side walls of immediately adjacent projections 42, and so that they are too small for the formation of significant liquid flows in the direction of the spacing in the partial volumes lying between immediately adjacent projections 42.

(14) The thickness of the projections 42 is selected such that they remain stable during the anticipated operating life of the liquid tank 10.

(15) When choosing the usual materials for fabricating the upper shell 12 and the lower shell 18, i.e., for example, thermoplastics, an optimum ratio of approximately 0.2 to 3 results of projection thickness to spacing 46 measured in the same direction between two adjacent projections 42. In the example shown, the ratio of projection thickness to spacing 46 is slightly smaller than 1, approximately 0.85, because the spacing 46 is somewhat larger than the thickness of the associated projections 42.

(16) The upper and lower shell parts 12 and 18 can respectively be fabricated in an injection mold in one step and then joined to each other at their joining flanges 24 and 46. Here, the relief structure 40 is formed immediately during the casting fabrication of the lower shell part 18. There is thus no need to form a relief structure on a separate component and connect the separate component to one of the shell parts 12 and 18, which considerably reduces the expense of producing the liquid tank 10 presented here compared to the prior art.

(17) In principle, the liquid tank shown in FIG. 1 can hold any liquid, in particular operating liquids for motor vehicles. Particularly preferably the liquid tank 10 is an SCR tank, which is configured and intended to hold aqueous urea solution, which in turn is used in motor vehicles for the selective catalytic reduction of exhaust gasses, and thus for exhaust-gas cleaning. Aqueous urea solution for this purpose that is available commercially is known under the trade name ADBLUE.