Urea aqueous solution filtering device

Abstract

The invention relates to a device for filtering an aqueous urea solution in an SCR exhaust gas aftertreatment device for injecting the aqueous urea solution into an exhaust gas pipe, comprising a filter housing and a filter (10) arranged inside the filter housing. In order to provide a filter device with a simple structure, a reduced risk of damage and improved interchangeability of components, the invention is characterized in that a volume compensation foam (12) is arranged between the filter housing and the filter (10), the volume compensation foam (12) is detachably mounted on the filter (10) and can be flushed by an aqueous urea solution.

Description

Technical Field

[0001] The present invention relates to an apparatus for filtering an aqueous urea solution in an SCR exhaust gas aftertreatment device, the apparatus injecting the aqueous urea solution into the exhaust gas pipe. Background Technology

[0002] Due to increasingly stringent emission regulations, modern diesel vehicles are equipped with SCR (Selective Catalytic Reduction) exhaust aftertreatment systems, requiring the injection of urea-water solution (HWL) into the diesel engine's exhaust pipe. HWL hydrolyzes to produce ammonia (NH3) and carbon dioxide (CO2). The ammonia then reacts with harmful nitrogen oxides (NOx) in the exhaust gas. x The reaction produces harmless nitrogen gas (N2) and water (H2O).

[0003] HWL filtration is crucial for ensuring system efficiency and lifespan. Filtration removes impurities and particles from the HWL that can clog or damage downstream nozzles or catalytic converters.

[0004] HWL is primarily composed of water. Therefore, after the diesel engine is turned off, the HWL may freeze at low ambient temperatures. The resulting increase in volume can generate high pressure within the filter unit, potentially damaging or destroying its components.

[0005] EP 2489845 B1 discloses a structure disposed within a filtration device in which an elastomeric membrane is embedded in a freeze-thaw compensation foam to prevent it from contacting the high-pressure water layer (HWL). This design of the elastomeric membrane and freeze-thaw compensation foam allows its deformation to limit the increase in internal pressure.

[0006] In terms of components and manufacturing processes, this structure is relatively complex. To protect the freeze-compensating foam from contact with the HWL, the elastomeric membrane must be installed within the sealing ring of the pump connection housing, and additional sealing elements must be provided. There is also an additional risk of damage to the flexible elements when screwing the pump connection housing into the filter housing. Because the elastomeric membrane is installed within the sealing ring of the pump connection housing, it must be replaced simultaneously with the filter.

[0007] Therefore, the object of the present invention is to provide a simpler filtration device that reduces the likelihood of damage and improves the interchangeability of its components. Summary of the Invention

[0008] The problem is solved by a device for filtering HWL in an SCR exhaust aftertreatment unit, which injects HWL into the exhaust pipe.

[0009] The filtration device of the present invention is characterized by arranging volume-compensating foam between the filter housing and the filter, so that it can be surrounded by HWL (high volume volume). This invention overcomes for the first time the technical prejudice that "direct contact between HWL and volume-compensating foam will damage the latter and therefore must be avoided."

[0010] This filtration device features a simple design and safe installation. The volume-compensating foam can be pre-attached to the filter in a detachable manner and inserted into the filter housing along with the filter. Precise installation is unnecessary, and the risk of damage during installation is minimized. If the volume-compensating foam needs to be replaced, this invention allows for the replacement of only the volume-compensating foam for the first time. This avoids time-consuming pre-assembly, including installation, and also avoids replacing unnecessary parts. The structure is intentionally designed so that the volume-compensating foam can be flushed with a urea solution. Therefore, the volume increase that occurs during freezing acts uniformly on the volume-compensating foam from all directions. This effectively counteracts the harmful pressure increase to the filter components.

[0011] According to a preferred embodiment, the volume-compensating foam is a closed-cell foam, characterized in that the HWL cannot permeate into the pores of the foam. As the volume of the frozen HWL increases, the pores are compressed, thereby limiting the increase in pressure inside the filtration device.

[0012] Alternatively, the volume-compensating foam can be an open-cell foam that is surface-sealed or otherwise sealed. Similar to closed-cell foam, sealing prevents HWL from entering the pores of the volume-compensating foam. Open-cell foam treated in this way has advantageous properties in compensating for the increase in HWL volume.

[0013] According to another preferred embodiment, the volume-compensating foam is composed of ethylene-propylene-diene rubber (EPDM). EPDM has high chemical resistance and long-term aging resistance, and is mainly used as a sealing material in many fields, including the automotive industry. Due to its high resistance to external influences, it is particularly suitable as a volume-compensating foam or a component thereof.

[0014] According to another preferred embodiment, the volume-compensating foam comprises one or more components. Which variant is more advantageous for a particular application depends on factors such as the manufacturing process.

[0015] According to another preferred embodiment, the volume-compensating foam is mounted on a support. The support can be a simple component, for example, manufactured using a plastic injection molding process. The support may be equipped with a spring that engages with a corresponding complementary molded groove in the volume-compensating foam. This design allows for easier placement of the volume-compensating foam in the desired location.

[0016] According to a particularly preferred embodiment, the support is configured and designed to be positively and detachably connected to the filter. This design is particularly advantageous during assembly. The volume-compensating foam can be first attached to the support, then to the filter, and finally, the filter is inserted into the filter housing, at which point the volume-compensating foam automatically positions itself. If only one element of multiple volume-compensating foams needs to be replaced, the filter can be removed from the filter housing, the support removed from the filter, the corresponding volume-compensating foam element removed and replaced, and then the support reattached to the filter and inserted into the filter housing. Thus, the replacement of the volume-compensating foam element can be completed in seconds. Attached Figure Description

[0017] The apparatus of the present invention will now be described with reference to the accompanying drawings. It should be understood that the embodiments described herein are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention.

[0018] Figure 1 For a single element in a multi-part volume-compensating foam;

[0019] Figure 2 For support;

[0020] Figure 3 In the pre-assembled state, Figure 1 The four components of the volume-compensating foam shown are connected to Figure 2 On the bracket shown; and

[0021] Figure 4 For further, such as Figure 3 The diagram shows a partial cross-sectional view of the pre-assembled state, in which the support and volume compensation foam are connected to the filter.

[0022] Figure label:

[0023] 10 Filters

[0024] 11 components

[0025] 12 Volume Compensation Foam

[0026] 14 supports

[0027] 15 Grooves

[0028] 16 Filter Carrier

[0029] 18 Filter elements

[0030] 20 grooves

[0031] 22 Springs Detailed Implementation

[0032] Figure 1A single element 11 of a multi-piece volume-compensating foam 12 is shown. The element 11 shown is part of a four-piece volume-compensating foam 12 and is therefore approximately quarter-circular in shape. Four such elements 11 are equidistantly distributed along the circumference, collectively forming a cylinder. Thus, each element 11 is essentially partially cylindrical for optimal arrangement within a cylindrical filter housing (not shown) and Figure 4 The filter 10 shown is located between the layers. In the lower region, the element 11 of the volume-compensating foam 12 is conical and has thicker walls in certain sections. The outer contour of this region is adapted to the internal geometry of the filter housing. Figure 4 As shown, in the assembled state, this part is located below the filter 10. The design of the volume-compensating foam 12 basically follows the goal of occupying the largest possible volume within the filter housing. On the one hand, this reduces the amount of HWL in the filter 10, resulting in less volume expansion of HWL during freezing. At the same time, the ability of the volume-compensating foam 12 to compensate for the increase in HWL volume is enhanced. The element 11 of the volume-compensating foam 12 has grooves 20 on its longitudinal sides for attaching the element 11 to the bracket 14 shown below.

[0033] Figure 2 A bracket 14 is shown, which is an injection-molded plastic component and is generally shaped like an open cylinder. The bracket 14 shown in the figure has eight springs 22 on its outer side, two of which are used to secure elements 11 of volume-compensating foam 12 and are designed to engage with grooves 20. Thus, four elements 11 of the volume-compensating foam 12 can be mounted on the bracket 14.

[0034] Figure 3 The pre-assembled state is shown, with the elements 11 of the four volume-compensating foams 12 attached to the bracket. As shown, gaps are left between the individual elements 11 of the volume-compensating foams 12. Furthermore, the bracket 14 has an opening on one side, a design that provides a degree of flexibility or elasticity, greatly simplifying the subsequent installation process of the filter 10 and the filter housing.

[0035] from Figure 3 It can also be seen that the support 14 and the element 11 of the volume-compensating foam 12 are provided with aligned grooves 15, which ensures that HWL can flow evenly to the volume-compensating foam from all directions. This design ensures that when the volume of HWL increases due to freezing, the pressure can be evenly distributed on all parts of the volume-compensating foam 12.

[0036] Figure 4 The filter 10 is shown, with volume-compensating foam 12 mounted on the filter 10 by means of a bracket 14. Figure 4The right half is a sectional view, and the left half is an unsectional view. In this simplified illustration, the filter 10 consists of a filter carrier 16 and a filter element 18. The bracket 14 is designed to be orthogonally connected to the lower part of the filter carrier 16, thereby ensuring that the filter 10 with pre-installed volume compensation foam 12 can be safely and quickly installed into the filter housing.

[0037] Assembly of the embodiment shown in the figure includes the following steps performed in sequence: pre-assembling the elements 11 of the volume compensation foam 12 onto the bracket 14, securing the bracket 14 to the filter carrier 16 of the filter 10, and inserting the filter 10 into the filter housing. If it is necessary to replace a single or all of the elements 11 of the volume compensation foam 12, the disassembly must be performed in reverse order.

Claims

1. An apparatus for filtering an aqueous urea solution in an SCR exhaust gas aftertreatment device, the apparatus for injecting the aqueous urea solution into an exhaust gas pipe, comprising a filter housing and a filter (10) disposed within the filter housing, characterized in that, A volume compensation foam (12) is provided between the filter housing and the filter (10), and the volume compensation foam (12) is detachably fixed to the filter (10) so as to be rinsed by a urea aqueous solution.

2. The apparatus according to claim 1, characterized in that, The volume compensation foam (12) is at least partially arranged on the radial outer circumference of the filter (10).

3. The apparatus according to claim 1, characterized in that, The volume compensation foam (12) is a closed-cell foam or an open-cell foam with surface sealing treatment.

4. The apparatus according to claim 1, characterized in that, The volume compensation foam (12) is made of or contains ethylene-propylene-diene rubber.

5. The apparatus according to claim 1, characterized in that, The volume compensation foam (12) is designed as a single piece or multiple pieces.

6. The apparatus according to any one of claims 1-5, characterized in that, The volume compensation foam (12) is detachably mounted on the bracket (14).

7. The apparatus according to claim 6, characterized in that, The bracket (14) is positively connected to the filter (10).

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