Abstract
A device for filtering a urea-water solution in an SCR exhaust gas aftertreatment device for injecting the urea-water solution into an exhaust gas train. The filtering device includes a filter housing and a filter which is arranged in an interior of the filter housing. In order to provide a simpler filtration device in which the susceptibility to damage is reduced and the interchangeability of individual components is increased, a volume compensation foam is arranged between the filter housing and the filter, the volume compensation foam being detachably fastened to the filter such that it can be flushed around by the urea-water solution.
Claims
1. A device for filtering a urea-water solution in an SCR exhaust gas aftertreatment device for injecting the urea-water solution into an exhaust gas train, the device comprising: a filter housing, a filter arranged in an interior of the filter housing, and a volume compensation foam arranged between the filter housing and the filter, the volume compensation foam being detachably fastened to the filter such that the volume compensation foam can be flushed around by the urea-water solution.
2. The device according to claim 1, wherein the volume compensation foam is arranged at least partially on the radially outer circumference of the filter.
3. The device according to claim 1, wherein the volume compensation foam is a closed-cell foam.
4. The device according to claim 1, wherein the volume compensation foam is an open-pored foam with surface sealing.
5. The device according to claim 1, wherein the volume compensation foam comprises ethylene-propylene-diene rubber.
6. The device according to claim 1, wherein the volume compensation foam is made of one piece.
7. The device according to claim 1, wherein the volume compensation foam is made of several pieces.
8. The device according to claim 1, wherein the volume compensation foam is detachably mounted on a holder.
9. The device according to claim 6, the holder configured to be positively connected to the filter.
Description
DESCRIPTION OF THE DRAWINGS
[0018] The device according to the disclosure is explained below with reference to a preferred but not be intended to be a limiting embodiment in the drawing.
[0019] FIG. 1 shows a single element of a multi-piece volume compensation foam;
[0020] FIG. 2 shows a holder;
[0021] FIG. 3 shows a pre-assembled state in which four elements of the volume compensation foam according to FIG. 1 are attached to the holder according to FIG. 2; and
[0022] FIG. 4 shows a partially sectioned view of the further pre-assembled state in which the holder and the volume compensation foam are attached to a filter as shown in FIG. 3.
DETAILED DESCRIPTION
[0023] FIG. 1 shows a single element 11 of a multi-piece volume compensation foam 12. The element 11 shown is part of a four-piece volume compensation foam 12 and therefore roughly describes the shape of a quarter circle. Four such elements 11 are distributed equidistantly around a circumference and together form a cylinder. Each element 11 is therefore essentially partially cylindrical in order to be optimally arranged between a cylindrical filter housing not shown and a filter 10 indicated in FIG. 4. In its lower area, the element 11 of the volume compensation foam 12 is tapered and has thicker walls in some sections. The outer contour in this area is also orientated to the inner geometry of the filter housing. As can also be seen with reference to FIG. 4, this section is located below the filter 10 in the assembled state. The design of the volume compensation foam 12 basically follows the aim of occupying as large a volume as possible within the filter housing. On the one hand, this reduces the amount of HWL in the filter 10, which leads to a lower volume expansion of the HWL in the event of freezing. At the same time, the ability of the volume compensation foam 12 to compensate for the increasing volume of the HWL increases. On its longitudinal sides, the element 11 of the volume compensation foam 12 is provided with grooves 20, which serve to attach the element 11 to a holder 14 as described in the following figures.
[0024] One such holder 14 is shown in FIG. 2. It is an injection-moulded plastic part that essentially has the shape of an open cylinder. The holder 14 shown has eight springs 22 on its outside, two of which are each arranged for fastening an element 11 of the volume compensation foam 12 and are designed to engage in its grooves 20. In this way, four elements 11 of the volume compensation foam 12 can be mounted on the holder 14.
[0025] The pre-assembled state, in which the four elements 11 of the volume compensation foam 12 are attached to the holder, is shown in FIG. 3. As can be seen there, a gap is provided between the individual elements 11 of the volume compensation foam 12. In addition, the holder 14 is open on one side. This design creates a certain flexibility or elasticity, which considerably simplifies subsequent installation on the filter 10 and in the filter housing.
[0026] As can also be seen in FIG. 3, the holder 14 and the elements 11 of the volume compensation foam 12 have aligned recesses 15, which ensure that the HWL can evenly flow around the volume compensation foam from all sides. Such a design ensures that the pressure is evenly distributed over all sections of the volume compensation foam 12 in the event of an increase in volume of the HWL in the event of freezing.
[0027] FIG. 4 shows a filter 10 to which a volume compensation foam 12 is mounted with the aid of a holder 14. The right half of FIG. 4 shows a cutaway view, while the left half is uncut. In this simplified illustration, the filter 10 consists of a filter carrier 16 and a filter element 18. The holder 14 is designed in such a way that it can be positively connected to a lower section of the filter carrier 16. This enables the filter 10 with pre-mounted volume compensation foam 12 to be mounted securely and quickly in a filter housing.
[0028] The assembly of the embodiment shown in the figures consists of the following steps to be carried out in this sequence: Pre-assembly of the elements 11 of the volume compensation foam 12 on the holder 14, attachment of the holder 14 to the filter carrier 16 of the filter 10, insertion of the filter 10 into a filter housing. If individual or all elements 11 of the volume compensation foam 12 are to be replaced, disassembly must be carried out in reverse order.
LIST OF REFERENCE SYMBOLS
[0029] 10 Filter [0030] 11 Element [0031] 12 Volume compensation foam [0032] 14 Holder [0033] 15 Recess [0034] 16 Filter carrier [0035] 18 Filter element [0036] 20 Grooves [0037] 22 Springs
