FR2937877A1 - Filter for use in filtering system for filtering e.g. urea, in selective catalytic reduction exhaust treatment system of vehicle, has support structure supporting filtering material for forming dosing liquid flowing path - Google Patents

Abstract

The filter (106) has a dosing reservoir (102) for containing dosing liquid, and filtering material arranged in the dosing reservoir. A support structure supports the filtering material for forming a dosing liquid flowing path. A fixation mechanism e.g. hook, fixes the filter to the inlet opening and an outlet opening of the dosing reservoir. The support structure has ribs arranged on the filtering material. The support structure separates adjacent surfaces of the filtering material. Independent claims are also included for the following: (1) a system for filtering dosing liquid in an exhaust treatment system comprising a filter (2) a method for filtering dosing liquid in an exhaust treatment system.

Description

The present invention relates to filtration and more particularly to filtration of a dosing fluid in a secondary exhaust treatment system. Many internal combustion engines produce nitrogen oxides (NOx) as a residual product of combustion. Diesel engines in particular produce a relatively large amount of NOx in operation. The engines typically emit NOx from the engine exhaust stream. NOx is a pollutant that can aggravate asthmatic conditions, react with oxygen in the air to produce ozone and finally form nitric acid when dissolved in water. NOx emissions from internal combustion engines are often blamed for acid rain and mists. The release of NOx being undesirable, various plans were implemented to reduce NOx emissions. One of them is a secondary catalytic selective exhaust (SCR) exhaust treatment system. The SCR system reduces NOx emission by using a chemical reaction between the exhaust gas, an additive and a catalyst. A gaseous or liquid metering fluid (most often ammonia or urea) is added to the exhaust gas and is absorbed over a catalyst. The metering fluid reacts with the NOx in the exhaust gas to form harmless H2O (water vapor) and N2 (nitrogen gas). In operation, an SCR system typically involves a tank of metering fluid embedded in the vehicle. The metering fluid is pumped from the reservoir by an injector into the exhaust stream. One of the difficulties associated with SCR systems is contamination of the dosing fluid. This contamination may take the form of dust or other foreign debris suspended in the dosing fluid, fragments from SCR system elements, such as small elements from a centrifugal impeller of a pump, or other materials. This contamination can limit the flow of metering fluid throughout the SCR system, but is particularly problematic in the injector. Foreign matter may lodge in the relatively small injector, reducing or eliminating the flow of the metering fluid into the exhaust stream.

Some SCR systems include paper filters disposed in bodies located between the metering fluid reservoir and the injector to reduce the incidence of contaminants in the injected metering fluid. While these filters can improve the performance of the SCR system, they can also introduce new challenges. Paper filters have a contaminant retention capacity that is low enough to require regular maintenance over the life of the engine. This maintenance typically involves replacing or cleaning the paper filter. In addition, the dosing fluids used in SCR systems often have a relatively high freezing point. That of urea, for example, is around -11 degrees Celsius. If a metering fluid is in the filter body at low temperatures, the metering fluid in the filter housing will freeze, eliminating the flow of metering fluid and often damaging the SCR system. Therefore, vehicles equipped with SCR systems operating at low temperatures often include heaters in the filter housings of the SCR system. Existing approaches for filtering dosing fluids in SCR systems present high costs associated with both manufacturing and maintenance. Regular replacement of the paper filter elements may require significant maintenance costs and the addition of a heating element to a filter body increases the cost of manufacturing the system. These costs are ultimately borne by the buyers, owners and drivers of the vehicle using these systems. From the elements described above, it is clear that there is a demand for an apparatus, a system and a method capable of filtering a dosing fluid in an SCR system. Advantageously, such an apparatus, system and method would reduce the cost of operation and manufacture of the SCR system while filtering contaminants from the metering fluid.

The present invention has been developed in response to the present state of the art and in particular in response to problems and needs in the art that have not yet been fully resolved by the filtration methods currently available in the art. secondary exhaust treatment systems. Accordingly, the present invention has been developed to provide an apparatus, system, and method for filtering a dosing fluid in an exhaust secondary treatment system that overcomes many, if not all, of the disadvantages of the process. art mentioned above. A filter is provided with a plurality of modules configured to functionally perform the necessary steps of metering fluid filtration. These modules in the described embodiments include a metering tank configured to hold a metering fluid, a filter material disposed in the metering tank, and a support structure supporting the filter material to form a flow path of the metering fluid. .

The filter material, in one embodiment, is disposed at an outlet of the metering tank so that the metering fluid flows through the filter material before or at the outlet of the metering tank. In another embodiment, the filter material is disposed at an inlet of the metering reservoir so that the metering fluid flows through the filter material before or upon entry into the metering tank. The filter, in a further embodiment, includes a securing mechanism configured to attach the filter to one of an inlet port and an outlet port of the metering tank. The filter material, in one embodiment, comprises meltblown polymeric microfilaments of substantially constant diameter. In another embodiment, the structure comprises one or more ribs disposed on the filter material. In a further embodiment, the filter material comprises a plurality of layers, each of the plurality of layers having a single and substantially constant porosity, the plurality of layers being arranged such that the porosity decreases from a filter inlet to a plurality of layers. filter output. In another embodiment, the filter material may comprise a material selected from the group consisting of nylon, polyester, poly (oxymethylene) (POM), polybutylene terephthalate (PBT), poly (ethylene terephthalate) (PET), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), high-density polypropylene, poly (fluorethylene), poly (vinylidene difluoride), poly (perfluoroalkoxy) PFA, poly (isobutylene), Viton, low density poly (ethylene) and high density poly (ethylene). In another embodiment, the filter material comprises a thick material.

A system of the present invention is also provided for filtering a dosing fluid into an exhaust secondary treatment system. The system can be embodied by a metering fluid for a secondary exhaust treatment system, a metering tank configured to hold the metering fluid, a filter, a pump configured to pump the metering fluid and an injector configured to inject. the metering fluid in an exhaust stream. In a particular embodiment, the filter in the system comprises a filter material disposed in the metering tank so that the metering fluid flows through the filter material before exiting the metering tank. The filter material may further comprise a support structure supporting the filter material to form a flow path of a dosing fluid. The filter material of the system may further be disposed in the dosing tank at an outlet of the dosing tank, so that the dosing medium flows through the filter material before or at the outlet of the dosing tank in a embodiment. In another embodiment, the system may include a heater configured to heat the metering fluid and the filter material in the metering tank. The dosing fluid, in one embodiment of the system, is a nitric oxide (NOx) reducing agent. The dosage fluid, in another embodiment, is selected from the group consisting of urea, ammonia and a hydrocarbon. In another embodiment of the system, the filter material may comprise a plurality of layers, each of the plurality of layers having a single and substantially constant porosity, the plurality of layers being arranged such that the porosity decreases by one input of the plurality of layers. filter at an output of the filter. A method of the present invention is also disclosed for filtering a dosing fluid into an exhaust secondary treatment system. The method in the described embodiments substantially comprises the steps necessary to perform the functions set forth above with respect to the operation of the apparatus and system described. In one embodiment, the method includes storing a metering fluid in a metering reservoir, the reservoir containing a filter material. The method may also include driving the metering fluid through the filter material. In one embodiment, the method further comprises dispensing metering fluid from the reservoir. In a further embodiment, the method comprises heating the dosing fluid in the dosing tank. In another embodiment, the method comprises pumping the metering fluid into a recirculation line. A method of the present invention is also disclosed for deploying a filter for a dosing fluid in an exhaust secondary treatment system. The method, in the described embodiments, substantially comprises the steps necessary to perform the functions presented above with respect to the operation of the apparatus and system described. In one embodiment, the method includes forming a filter material having a lower porosity than a contaminant in a dosing fluid. The method, in some embodiments, further comprises placing the filter material in a metering tank, the metering tank being configured to hold a metering fluid used in a secondary exhaust treatment system, the material filter being positioned at a location such that the metering fluid passes through the filter material before exiting the tank.

Any reference in this specification to features, advantages or similar language does not imply that all the features and advantages that can be achieved with the present invention are grouped together or should be grouped together in a single embodiment. of the invention. The language referring to features and advantages is rather meant to mean that a specific feature or benefit described in connection with an embodiment is included in at least one embodiment of the present invention. Thus, the mention of the features and advantages and of a similar language throughout this memory may refer to the same embodiment, but not necessarily.

In addition, the described features and advantages of the invention can be suitably combined in one or more embodiments. Those skilled in the art will recognize that the invention may be practiced without one or more of the specific features or advantages of a particular embodiment. In other cases, additional features and advantages may be recognized in some embodiments without being present in all embodiments of the invention.

These features and advantages of the present invention will become more apparent from the following description and appended claims, or may be retained from the practice of the invention as mentioned below.

In order to allow a better understanding of the advantages of the invention, a more specific description of the invention briefly described above will be made with reference to specific embodiments illustrated in the accompanying drawings. It is understood that these drawings represent only typical embodiments of the invention and therefore should not be construed as limiting its scope; the invention will therefore be described and explained with additional specificity and detail through the use of the accompanying drawings, in which: FIG. 1 is a block diagram illustrating an embodiment of a dosing system for a secondary exhaust treatment system; Fig. 2 is a block diagram illustrating an embodiment of a metering system for an exhaust secondary treatment system according to the present invention; Fig. 3 is a block diagram illustrating an embodiment of a metering tank with an internal filter in a metering system for an exhaust secondary treatment system according to the present invention; Fig. 4 is a block diagram illustrating an embodiment of a metering tank with internal filters in a metering system for an exhaust secondary treatment system according to the present invention; Fig. 5 is a block diagram illustrating an embodiment of a metering system for an exhaust secondary treatment system using a thick filter material according to the present invention; Fig. 6 is a block diagram illustrating an embodiment of a metering system for an exhaust secondary treatment system using gradient density depth filtration according to the present invention; Fig. 7 is a cross-sectional view of an embodiment of a gradient density depth filtration system according to the present invention; Fig. 8 is an enlarged top view of meltblown microfilaments constituting a first layer of a meltblown filtration assembly according to some embodiments of the present invention; and Fig. 9 is a schematic flowchart illustrating an embodiment of a method of deploying a filter for a dosing fluid in an exhaust secondary treatment system according to the present invention. Reference throughout this memory to an embodiment or similar expression means that a particular feature or structure described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the expression in one embodiment and the like throughout this memory may, but not necessarily, refer to the same embodiment.

In addition, the described features or structures of the invention may be suitably combined in one or more embodiments. In the following description, many specific details are provided to allow a thorough understanding of the embodiments of the invention. Those skilled in the art will recognize, however, that the invention may be practiced without one or more of the specific details or with other methods, components, materials, etc. In other cases, well known structures, materials or operations are not shown or described in detail in order to avoid obscuring certain aspects of the invention.

Fig. 1 is a block diagram illustrating an embodiment of a metering system 100 for an exhaust secondary treatment system. The metering system 100 comprises a metering tank 102, a heating device 104, a filter 106, a pump 108, an injector 110 and an exhaust stream 112. The metering system 100 injects a metering fluid into a flow exhaust 112 to reduce the pollutants present in the exhaust stream 112. The metering tank 102, in one embodiment, contains a metering fluid for use in the metering system 100. The metering tank 102 may include an outlet 114 through which the dispensing fluid leaves the dosing tank 102. The dosing tank 102 may comprise any material capable of containing the dosing fluid, such as a polymer, a metal or the like. The filter 106 receives the metering fluid from the metering tank 102. The filter 106 may be connected to the metering tank by a hose, tube, channel, or the like. The filter 106 removes contaminants from the dosing fluid. The filter 106 may comprise a cellulosic material, a polymeric material, a mesh or the like. In one embodiment, the filter 106 includes a heater 104 configured to heat the metering fluid in the filter 106. The heater 104 maintains the metering fluid in the filter 106 above the freeze temperature of the filter. dosing fluid. In one embodiment, the heater 104 includes an electrical resistance element that generates heat in response to an electrical current passing through the element.

The pump 108 receives the metering fluid from the filter 106 and pumps the metering fluid into the system 100. The pump 108 may be connected to the filter 106 by a hose, tube, channel, or the like. The pump 108, in one embodiment, may include a bladder pump, a peristaltic pump or any pump commonly used in the art.

The injector 110 injects a metering fluid into the exhaust stream 112, in one embodiment. The injector 110 may include one or more orifices configured to deliver the metering fluid to the exhaust stream 112. Figure 2 is a block diagram illustrating an embodiment of a metering system 200 for a secondary treatment system. exhaust system according to the present invention. The metering system 200 may include a metering reservoir 202 with an internal filter 204, a pump 206, an injector 208 and an exhaust stream 210. The metering system 200 injects a metering fluid into an exhaust stream 210. in order to reduce the amount of pollutants in the exhaust stream 210. The metering tank 202, in one embodiment, includes an inlet 212, an outlet 214, and an internal filter 204. The metering tank 202 receives, stores, and provides a dosage fluid for use in the assay system 200. The assay fluid may be any reducing agent used to treat nitrogen monoxides (NOx) in an exhaust stream. By way of example, the dosing fluid can be materialized by urea, ammonia, a hydrocarbon or the like. The metering reservoir 202 may be composed of any material capable of containing the metering fluid, such as a polymer, a metal, or the like. Inlet 212 receives a flow of metering fluid 216. Flow of metering fluid 216 enters metering reservoir 202 as illustrated by the dashed arrows. The outlet 214 delivers a flow of metering fluid from the metering reservoir 202 to other elements of the metering system 200. The internal filter 204, in one embodiment, is disposed in the metering tank 202. The arrangement of Filter 204 in the metering tank 202 eliminates the need for a separate heater for the filter 204. In one embodiment, the inner filter 204 is disposed in the metering tank 202 at the outlet 214 of the reservoir. In this embodiment, the dosing fluid leaving the metering reservoir 202 passes through the internal filter 204. As the metering fluid passes through the internal filter 204, contaminants suspended in the metering fluid are trapped by the filter. internal 204. The internal filter 204 may comprise a filter layer. The filter material may include any filter material capable of removing contaminants from a dosing fluid. For example, the filter layer may comprise a cellulosic material. In another example, the filter layer may be composed of a polymeric material. In one embodiment, the filter layer may be formed of a meltblown thick polymer filter material, as described below with respect to Fig. 7. In some embodiments, the inner filter 204 is connected. to the dosing tank 204 by a fastening mechanism 218. The fastening mechanism 218 may consist of a clip, a hook, a pawl, a thread, a hose, a tube, a channel or other fastening mechanism 218 known in the art. In an alternative embodiment, the inner filter 204 may be attached to the metering reservoir 202 by a weld, adhesive, or the like. In yet another embodiment, the inner filter 204 may be formed with the metering reservoir 202. By way of example, the inner filter 204 may be molded simultaneously with the molding of the metering reservoir 202.

The pump 206 receives the metering fluid from the metering tank 202 and pumps the metering fluid into the system 200. The pump 206 may be connected to the filter 204 by a hose, tube, channel, or the like. Pump 206, in one embodiment, may include a bladder pump, peristaltic pump, or other pump commonly used in the art.

In an alternative embodiment, the pump 206 may be disposed in the metering tank 202. The pump 206 may act on the metering fluid before it passes through the inner filter 204. In another embodiment, the pump 206 can be arranged in the dosing tank 202 and act on the dosing fluid after passing through the internal filter 204. By way of example, the pump 206 can be located in the internal filter 204 and pump the fluid of dosing through the outlet 214 of the metering tank 202. The injector 208 injects the metering fluid into the exhaust stream 210, in one embodiment. The injector 208 may include one or more orifices configured to deliver the metering fluid to the exhaust stream 210. In some embodiments, the metering system 200 may comprise a recirculation line 220. In some embodiments, the recirculation line 220 returns the metering fluid to the metering tank 202 from the pump 206. The metering system 200 can recirculate the metering fluid through the recirculation line 220 in response to a determination that the fluid dosing is not injected into the exhaust stream 210, for example, when the engine is stopped and does not produce an exhaust. Use of the recirculation line 220 may be performed to protect the dosing fluid in the pump 206 of the gel during operation of the metering system 200 at a low temperature. Figure 3 illustrates a cross-sectional view of an embodiment of a metering reservoir 302 with an internal filter in a metering system for an exhaust secondary treatment system according to the present invention. The metering reservoir 302, in one embodiment, includes an inlet 212, an outlet 214, an internal filter 304, and a heater 306. The metering reservoir 302 receives, stores, and delivers a metering fluid for use therein. in the dosing system. The metering reservoir 302 may be composed of any material capable of containing the metering fluid, such as a polymer, a metal or the like. In one embodiment, the inlet 212 and the outlet 214 are similarly configured to the bearing components of the same numerical reference described in connection with FIG. 2. The internal filter 304 is disposed in the metering tank 302 in a of realization. The internal filter 304 may comprise a filter material 308 and a support structure 310. The internal filter 304 filters a flow of metering fluid 216. The filter material 308 may be composed of any carrier capable of removing contaminants from a dosing fluid. For example, the filter material 308 may be composed of a cellulosic material. In another example, the filter material 308 may be composed of a polymeric material. In one embodiment, the filter material 308 may be composed of a meltblown polymeric thick filter material, as described below with respect to Fig. 7. As will be appreciated by those skilled in the art, the material Filter 308 may be composed of any material used in the filter supports. For example, the filter material may include nylon, polyester, poly (oxymethylene) (POM), polybutylene terephthalate (PBT), polyethylene terephthalate (PET) ), poly (ethylene naphthalate) (PEN), polybutylene naphthalate (PBN), high-density polypropylene, poly (fluorethylene), polyvinylidene difluoride, poly ( perfluoroalkoxy) PFA, poly (isobutylene), Viton, low density poly (ethylene) and / or high density poly (ethylene). The filter material 308 may be supported by a support structure 310. In one embodiment, the support structure 310 supports the filter material 308 to form a flow path of the dosing fluid 216. The support structure 310 may separate adjacent surfaces of the filter material 308 to create a flow path for the metering fluid 216. As will be apparent to those skilled in the art in light of the present description, the filter material, depending on its structural integrity, can - even compose the support structure.

For example, the support structure 310 may include one or more ribs on an inner surface of the filter material 308. The filter material 308 in the present example may be formed as a sleeve, the opening of the sleeve being attached to the outlet 214 of the metering reservoir 302. The inner surface of the sleeve-shaped filter material 308 may be traversed by one or more support structure-forming ribs 310 which maintain the adjacent inner surfaces of the sleeve-shaped filter material spaced apart to form a metering fluid flow path 216. The heating device 306, in one embodiment, heats a metering fluid in the metering tank 302. The heating device 306 can also heat the metering fluid around the filter 304. The heating of the dosing fluid keeps the dosing fluid above a minimum temperature required for use of the back fluid. age. For example, when urea is used as a metering fluid, the heater 306 can maintain the metering fluid in the reservoir at a temperature above the freezing point of the urea, which is about - 11 degrees Celsius. Fig. 4 illustrates a cross-sectional view of an embodiment of a metering reservoir 402 with internal filters in a metering system for an exhaust secondary treatment system according to the present invention. The metering reservoir 402, in one embodiment, includes an inlet 212, an outlet 214, an internal inlet filter 404, an internal outlet filter 406 and a heater 306. The metering tank 402 receives, stores and delivers a dosing fluid for use in the dosing system. The metering reservoir 402 may be composed of any material capable of containing the metering fluid, such as a polymer, a metal, or the like. The input 212 and the output 214 are preferably configured similarly to the components having the same reference numerals described in connection with FIG. 2. The heater 306 is preferably configured similarly to a component bearing the same numeral reference described with reference to FIG. 3. The internal input filter 404 is disposed in the dosing tank 402 in one embodiment. The internal inlet filter 404 may be composed of a filter material 308 and a support structure 310. The internal inlet filter 404 filters a flow of metering fluid 216 as it enters the metering reservoir 402. The filter material 308 and the support structure 310 are preferably similarly configured to the components having the same numerical references described in connection with FIG. 3. In one embodiment, the internal input filter 404 is disposed in the metering reservoir 402 and attached to the metering reservoir 402 at the inlet 212. The internal inlet filter 404 can be positioned in the path of the metering fluid flow 216 as it enters the metering reservoir 402. In one embodiment, the internal input filter 404 may be formed with a sleeve configuration as described above in connection with FIG. 3, the opening of the sleeve surrounding the array input 212. In an alternative embodiment, the internal input filter 404 may be formed with a basket configuration, the opening of the basket surrounding the input 212. The internal output filter 406 is disposed in the dosing tank 402 in one embodiment. The internal output filter 406 may be composed of a filter material 308 and a support structure 310. The internal input filter 406 filters a flow of dosing fluid 216 at its outlet from the dosing tank 402. The material 308 and the support structure 310 are preferably similarly configured to components having the same reference numerals described with reference to FIG. 3. In one embodiment, the internal output filter 406 is disposed in the reservoir metering device 402 and attached to the metering tank 402 at the outlet 214. The internal outlet filter 406 can be positioned in the path of the metering fluid flow 216 at its outlet from the metering tank 402. In one embodiment the internal outlet filter 406 can be formed with a sleeve configuration as described above in connection with FIG. 3, the opening of the sleeve surrounding the outlet 214 of the reservoir of In an alternative embodiment, the internal output filter 406 may be formed with a basket configuration, the opening of the basket surrounding the outlet 214. Figure 5 illustrates an embodiment of a dosing system. 500 for a secondary exhaust treatment system using a thick filter material according to the present invention. The metering system 500 comprises a metering tank 102, a filter body 502, a thick filter material 504, a pump 108, an injector 110 and an exhaust stream 112. The metering system 500 injects a dosing medium into an exhaust stream 112 to reduce the amount of pollutants present in the exhaust stream 112. The metering tank 102, the pump 108, the injector 110 and the exhaust stream 112 are preferably configured from similar way to components bearing the same reference numerals described in connection with Figure 1.

The filter body 502, in one embodiment, forms a structure for containing the thick filter material 504 and forms a passage for driving the metering fluid through the thick filter material 504. In one embodiment, the filter body 502 receives a flow of metering fluid from the metering tank 102. The filter body 502 can be maintained, which means that the thick filter material 504 can be removed from the filter body 502 and replaced. In another embodiment, the filter body 502 can be releasably coupled to the metering system 500, so that the filter body with the associated thick filter material 504 can be removed and replaced. In yet another embodiment, the filter body 502 may be a permanent filter that does not require maintenance under normal conditions. In one embodiment, the filter body 502 is positioned in a metering fluid flow path between the metering reservoir 102 and the pump 108. In another embodiment, the filter body 502 is positioned in a metering fluid flow path between pump 108 and injector 110. In some embodiments, filter body 502 may further include a heater. The thick filter material 504 intersects the metering fluid flow path and removes contaminants from the metering fluid as it passes through the thick filter material 504. In one embodiment, the thick filter material 504 comprises a series of layers. having a decreasing porosity in the direction of the flow path of the dosing fluid. The thick filter material 504 is discussed in greater detail with respect to Fig. 7. In one embodiment, the thick filter material 504 has a cartridge filter configuration well known in the art. The thick filter material 504 may be composed of a meltblown polymeric material. In one embodiment, the thick filter material 504 may be composed of a cellulosic material. In yet another embodiment, the thick filter material 504 may be composed of a combination of materials. By way of example, in one embodiment, the thick filter material 504 may be composed of a pleated paper material in a cartridge configuration with one or more layers of polymeric material disposed on an outer surface of the pleated paper material. . Figure 6 illustrates an embodiment of a metering system 600 for an exhaust secondary treatment system using gradient density depth filtration according to the present invention. The metering system 600 comprises a metering tank 102, a first filter body 602, a thick filter material 504, a pump 108, a second filter body 604, an injector 110 and an exhaust stream 112. assay 600 injects a metering fluid into an exhaust stream 112 to reduce the amount of pollutants present in the exhaust stream 112. The metering tank 102, the pump 108, the injector 110 and the exhaust stream 112 preferably have a configuration similar to the components bearing the same numerical references described with reference to FIG. 1. The thick filtering material 504 is preferably configured similarly to a component bearing the same numerical reference described with reference to FIG. 5. The first filter body 602, in one embodiment, is configured similarly to the filter body 502 described in connection with Fig. 5. The first filt body Re 602 may be disposed in a metering fluid flow path between the metering reservoir 102 and the pump 108. The first filter body 602 may contain a thick filter material 504 for filtering the metering fluid. In some embodiments, the first filter body 602 may further include a heater. The second filter body 604, in one embodiment, is similarly configured to the filter body 502 described in connection with Fig. 5. The second filter body 604 may be disposed in a fluid flow flow path The second filter body 604 may contain a thick filter material 504 for filtering the dosing fluid. In some embodiments, the second filter body 604 may further include a heater. Referring now to FIG. 7, a gradient density depth filtration system 700 for a dosing fluid according to the present invention may generally comprise a meltblown filtration assembly 702 having multiple layers formed by In the present invention, meltblowing 704, 706 and 708 have variable porosities, the term porosity as used herein denoting the percentage of space in the layer. Indeed, the variation in porosity produces a corresponding variation in interstitial size or pore size, thus conferring variable layer filtration capabilities. This method of relying on porosity or density gradient variation to vary the filterability of a layer facilitates an effective thick filter material type filter made of acetal and / or other thermoplastic material. whose dimensions are substantially stable compatible with various dosing fluids. In some embodiments, for example, a first layer 704 of the meltblown filtration assembly 702 may have a porosity of between about 90 and 98% to provide initial filtration of small particles. The first layer 704 may be coupled to a second layer 706 adapted to filter small particles of reduced magnitude. A porosity corresponding to the second layer 706 may be, for example, between about 85 and 97%. Finally, the second layer 706 of the meltblown filtration assembly 702 may be coupled to a third layer 708 adapted to filter fine particles. A porosity corresponding to the third layer 708 may be, for example, between about 80 and 96%. Thus, the meltblown filtration assembly 702 of the present invention provides progressively finer filtration of a metering fluid having a direction of movement 216 from the first layer 704 to the third layer 708. Of course, those skilled in the art will recognize that the first, second and third layers 704, 706 and 708 of the meltblown filtration assembly 702 described above are for illustrative purposes only and that a filter assembly formed by meltblowing 702 according to the present invention may comprise any number of layers arranged to provide progressively finer filtration. Further, in some embodiments, the meltblown filtration assembly 702 may comprise a graduated arrangement of meltblown microfilaments integrated into a unitary assembly, such that the meltblown filtration assembly blowing 702 is substantially free of individually identifiable layers. In one embodiment, the meltblown filtration assembly 702 may comprise a single layer.

In some embodiments, the meltblown filtration assembly 702 may be coupled to at least one general filtration element 708 adapted for relatively coarse filtration, thereby further contributing to a gradual filtration effect. In some embodiments, the meltblown filtration assembly 702 may be sandwiched between two general filter elements 708a and 708b to substantially encapsulate the more delicate meltblown layers of the formed filter assembly. by meltblowing 702, which protects the meltblown filtration assembly 702 while contributing to overall filtration. The general filter element 708a and 708b may comprise a direct spin nonwoven filter support, referring to the category of nonwoven materials in which the newly formed filaments are immediately subjected to cold air in order to stop them. mitigation. The general filter element 708a and 708b may have a porosity greater than a porosity corresponding to the first layer 704 of the meltblown filtration assembly 702, so that the general filter element 708a and 708b provide preliminary filtration of the particulate matter of relatively large size of a fluid. The general filter element 708a and 708b may comprise, for example, direct spunbond nylon, polyester, acetal, Teflon or other non-spunbonded filter media known in the art. art. the average filament diameter of such a carrier may be, for example, about 100 μm. Fig. 8 is an enlarged top view of meltblown microfilaments constituting a first layer of a meltblown filtration assembly according to some embodiments of the present invention. In one embodiment, a thermoplastic material whose dimensions are substantially stable such as acetal, can be formed by meltblowing to produce microfilaments 802 having a substantially constant diameter 804. In some embodiments, for example, a diameter 804 of each microfilament may be between about 2.5 and 30 μm. As illustrated in FIG. 8, the first layer 704 of the meltblown filtration assembly 702 of the present invention may have a porosity 806 of about 96% to provide coarse porosity filtration of a fluid. . The second layer 706, as shown in FIG. 7, may comprise microfilaments 802 whose diameter 804 is substantially equal to that of the filaments shown in FIG. 8. The microfilaments 802 of the second layer 706, however, may have a porosity 806. about 94% to ensure intermediate porosity filtration of the metering fluid. Finally, the third layer 708, illustrated in FIG. 7, may comprise microfilaments 802 whose diameter 804 is comparable to that of the first and second layers 704 and 706 represented by FIG. 7, although the third layer 708 may have a porosity. 806 of about 92 to ensure fine porosity depth filtration. The meltblown microfilaments 802 may be composed of meltblown polymeric microfilaments. In some embodiments, the microfilaments may include nylon, polyester, poly (oxymethylene) (POM), polybutylene terephthalate (PBT), polyethylene terephthalate (PET) poly (ethylene naphthalate) (PEN), polybutylene naphthalate (PBN), high-density polypropylene, poly (fluorethylene), polyvinylidene difluoride, poly (perfluoroalkoxy) ) PFA, poly (isobutylene), Viton, low density poly (ethylene) and / or high density poly (ethylene). The following schematic flowcharts are usually presented in the form of logical flowcharts. Thus, the order shown and the steps denoted indicate an embodiment of the method presented.

Other steps and methods may be envisaged, having a function, logic or effect equivalent to one or more steps or parts thereof, of the illustrated method. In addition, the format and symbols employed are provided to explain the logical steps of the process and are intended to be nonlimiting of the scope of the process. Although various types of arrows and various types of lines may be used in flowcharts, they are not intended to limit the scope of the corresponding process. Indeed, some arrows or other connecting elements can be used to indicate only the logical course of the process. For example, an arrow may indicate a waiting period or monitoring of indefinite duration between numbered steps of the process shown. In addition, the order in which a particular process takes place may be strictly in accordance or not with the order of the corresponding steps represented. Fig. 9 is a schematic flowchart illustrating an embodiment of a method 900 for deploying a filter for a metering fluid in an exhaust secondary treatment system according to the present invention. The method 900, in some embodiments, utilizes the system and apparatus of the preceding figures and will be discussed with reference to these figures. As shown in FIG. 9, the process 900 begins with the melt blowing 902 of the microfilaments 802. The microfilaments 802 may comprise a substantially stable thermoplastic material of substantially constant diameter, as described in connection with FIG. 8. Next, the microfilaments 802 are formed 904 into a layer having a substantially constant porosity 806. The microfilaments 802 may be formed into a plurality of layers, each layer having a different porosity 806. By way of example, the microfilaments may be formed into a first layer 704, a second layer 706 and a third layer 708, each layer having a progressively lower porosity 806. Then, a plurality of meltblown layers are arranged 906 as a function of the relative densities to form a filtration assembly 702. For example, the first layer 704, the second layer 706 and the third layer 708 discussed above. In one embodiment, the layers can be laminated to form a coherent filtration assembly 702. Next, the filter assembly 702 is disposed 908 in the dosing fluid flow path 216. The filter assembly 702 may be disposed 908 in a metering reservoir 202. In another embodiment, the filter assembly 702 may be disposed 908 in the metered fluid flow path 216 outside the metering reservoir 202. dosing tank, for example in a filter body 502. Finally, the dosing fluid is filtered 910 through the thick filter material of the filter assembly 702. Filtration 910 occurs when contaminants suspended in the fluid of The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The embodiments described must be considered in all respects as purely illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. Any changes that fall within the meaning and equivalence range of the claims must be incorporated into their scope.

Claims (17)

CLAIMS1 Filter for filtering a metering fluid in a secondary exhaust treatment system, characterized in that the filter comprises: a metering tank configured to hold a metering fluid; a filter material disposed in the dosing tank; and a support structure supporting the filter material to form a flow path of the dosing fluid. 2. Filter according to claim 1, characterized in that the filter material is disposed at an outlet of the metering tank so that the metering fluid passes through the filter material before or at the outlet of the metering tank. 3. Filter according to claim 1, characterized in that the filter material is disposed at an inlet of the metering tank so that the metering fluid passes through the filter material before or at the inlet of the reservoir. dosage. The filter of claim 1, characterized in that the filter further comprises an attachment mechanism configured to attach the filter to one of an inlet port and an outlet port of the metering tank. The filter of claim 1, characterized in that the filter material further comprises meltblown polymeric microfilaments of substantially constant diameter. 6. Filter according to claim 1, characterized in that the support structure comprises one or more ribs disposed on the filter material. Filter according to claim 1, characterized in that the filtering material comprises a plurality of layers, each of the plurality of layers having a single and substantially constant porosity, the plurality of layers being arranged so that the porosity decreases from an inlet of the filter at an output of the filter. 8. Filter according to claim 7, characterized in that the filtering material comprises a material selected from the group consisting of nylon, poly (ester), poly (oxymethylene) (POM), poly (butylene terephthalate) ( PBT), poly (ethylene terephthalate) (PET), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), high-density polypropylene, poly (fluorethylene) ), poly (vinylidene difluoride), poly (perfluoroalkoxy) PFA, poly (isobutylene), Viton, low density poly (ethylene) and high density poly (ethylene). 9. Filter according to claim 1, characterized in that the filter material comprises a thick material. A filtering system for a metering fluid in a secondary exhaust treatment system, characterized in that the system comprises: a metering fluid for an exhaust secondary treatment system; a dosing tank configured to contain the dosing fluid; a filter comprising: a filter material disposed in the dosing tank so that the dosing fluid flows through the filter material before exiting the dosing tank; and a support structure supporting the filter material to form a flow path of the dosing fluid; a pump configured to pump the dosing fluid; and an injector configured to inject the metering fluid into an exhaust stream. The system of claim 10, characterized in that the filter material is disposed in the dosing tank at an outlet port of the dosing tank so that the dosing fluid flows through the filter material before or after the outlet of the dosing tank. 12. System according to claim 10, characterized in that the system further comprises a heating device configured to heat the dosing fluid and the filter material in the dosing tank. 13. System according to claim 10, characterized in that the dosing fluid is a nitric oxide reducer (NOx). 14. System according to claim 10, characterized in that the dosing fluid is selected from the group consisting of urea, ammonia and a hydrocarbon. 15. System according to claim 10, characterized in that the filtering material comprises a plurality of layers, each of the plurality of layers having a single and substantially constant porosity, the plurality of layers being arranged so that the porosity decreases. a filter input to an output of the filter. 20 16. A dosing fluid filter apparatus characterized in that the apparatus comprises: a dosing fluid reservoir configured to hold a dosing fluid, the dosing fluid being used in an exhaust secondary treatment system; means disposed in the metering fluid reservoir for filtering the metering fluid; means for supporting the means disposed in the metering fluid reservoir for filtering the metering fluid, the metering means forming a metering fluid flow path through the means disposed in the metering fluid reservoir for filtering the dosing fluid. The metering fluid filter apparatus according to claim 16, characterized in that the apparatus further comprises means for heating the metering fluid in the metering tank. A method of filtering a dosing fluid in a secondary exhaust treatment system, characterized in that the method comprises: storing a dosing fluid in a dosing tank, the tank containing a filter material; driving the metering fluid through the filter material; and the metering fluid outlet of the reservoir. 19. The method of claim 18 characterized in that the method further comprises heating the dosing fluid in the dosing tank. 20. The method of claim 18, characterized in that the method further comprises pumping the metering fluid through a recirculation line. 21. A method of deploying a filter for a dosing fluid in a secondary exhaust treatment system, characterized in that the method comprises: forming a filter material having a minimum porosity lower than a contaminant in a dosing fluid; and placing the filter material in a dosing tank, the dosing tank being configured to hold a dosing fluid used in an exhaust secondary treatment system, the filter material being positioned at a location such as the fluid metering passes through the filter material before exiting the tank. 10