DE102004022798A1 - Filter for use in vehicle that generates hydrocarbon emissions comprises housing that contains filter element comprising adsorption resin particles on support - Google Patents

Abstract

A filter for use in a vehicle that generates hydrocarbon emissions comprises a housing that contains a filter element comprising adsorption resin particles on a support and has one side facing the hydrocarbon emission source and another side facing the atmosphere.

Description

The The invention relates to a filter element according to the preamble of the claim 1.

To the new guidelines for reducing hydrocarbon emissions (LEV = Low Emission Vehicle; ZEV = Zero Emission Vehicle; PZEV = Partial Zero Emission Vehicle) of passenger cars in California and the so-called green States of the USA, it is the goal of the manufacturer of activated carbon filters having tank ventilation systems, To reduce the emissions of the activated carbon filter suitable. To This reduction of the emissions of the activated carbon filter becomes multi-chamber systems or additional filter elements for Main activated carbon filter used.

Of the Main activated carbon filter can be a canister with an activated carbon bed. He serves while a refueling of the motor vehicle, the effluent from the fuel tank hydrocarbons catch. While of the driving operation, the fuel tank is then again with a backwashed and desorbed defined air volume. The desorbed air is supplied to the combustion air of the engine.

• 1. Aus dem Kraftstofftank entweichen weitere Kohlenwasserstoffe, die den Aktivkohlefilter wieder beladen, und
• 2. der Aktivkohlefilter selbst desorbiert aus seiner Restbeladung, d.h. aus der Menge an Kohlenwasserstoffen, die bei der Desorption nicht vollständig von der Aktivkohle heruntergespült werden konnte, eine bestimmte Menge an Kohlenwasserstoffen in die Atmosphäre.

If the motor vehicle remains exposed to sunshine, for example, after such a desorption process, then it heats up-and thus also the fuel tank together with the activated carbon filter. This heating up has two effects:

• 1. From the fuel tank escape more hydrocarbons that load the activated carbon filter again, and
• 2. The activated carbon filter itself desorbed from its residual load, ie from the amount of hydrocarbons that could not be completely washed down by the activated carbon in the desorption, a certain amount of hydrocarbons in the atmosphere.

Also in the field of intake air of internal combustion engines Additional filter elements for the reversible adsorption of hydrocarbons used. After switching off the internal combustion engine can over open Valve positions gasoline vapors through the intake tract of the internal combustion engine as emissions to Outside reach.

The EP 1 110 593 A1 describes an engine intake filter consisting of several layers, one of which is an activated carbon impregnated polyurethane foam acting as a hydrocarbon buffer. A shortcoming of this activated carbon impregnation is that over the binder adsorption capacity is lost. In addition, the hydrocarbon buffer is integrated in this known proposal in the actual engine intake filter, ie it is relaitv far away from the actual emission source.

The US 2003/0145732 A1 describes a solution proposal that is very close can be positioned at the emission source and also at very small flow cross sections has a low differential pressure. The disadvantage of this Suggested solution the relatively expensive Structure, as the component is mechanically very vulnerable.

To The legislation applicable from 2004 onwards may be replaced by a motor vehicle which: must meet the emission requirements under PZEV, a total amount of hydrocarbons of 0.35 g per specified test cycle do not exceed. This limit is set by the car manufacturers to appropriate Split components. For the tank ventilation system As a rule, specifications in the range of a maximum of 10 mg result Hydrocarbons in a given test cycle coming out of the Activated charcoal canisters can still be delivered to the atmosphere per day.

For the said Test cycle based on the specifications of the CARB (California Air Research Board) - Authority. in this connection becomes a complete fuel tank venting system Defined in such a way that it is pre-aged with a given Number of cycles loaded and rinsed again and again. That means it takes place a pre-aging in the form of several refueling and desorption cycles with following Resting phase and an adjoining temperature cycle of 18 ° C on 42 ° C and back again at 18 ° C Within 24 hours. This temperature cycle is two to drive through three times.

To reduce the hydrocarbons that still escape from the activated carbon canister due to these temperature cycles, various concepts have been developed:
US 2001/0020418 A1 discloses a canister in whose last, atmosphere-side chamber an active coal of high specific heat capacity is provided. Due to the high heat capacity, adsorption heat is absorbed and stored during the loading of the activated carbon with hydrocarbons, which is released again during the desorption, which is an endothermic process.

The US Pat. No. 6,503,301 B2 describes a two-chamber system in which the atmosphere-facing chamber contains a mixture of an adsorbent with a material of high heat capacity. The high heat capacity material absorbs and stores heat of adsorption when loaded with hydrocarbons and releases them again during desorption. The said material with the high heat capacity thus has the same effect as the activated carbon of high heat capacity described above.

The DE 199 48 537 A1 proposes a main activated carbon filter with an additional filter element, wherein the additional filter element has the property that it can be desorbed much faster compared to the main activated carbon filter due to its small size. For this known additional filter element, preference is given to a nonwoven coated with activated carbon, which is rolled up into a cylinder and through which it flows in its longitudinal direction. The auxiliary filter element, however, has the defect that it builds up an additional differential pressure, which can be very large due to the dense winding structure.

From the DE 199 52 092 C1 is an activated carbon filter is known, which is provided in particular for reducing the evaporation emissions from a fuel supply system. This known activated carbon filter has a first and a second connection section, a filter section with activated carbon between the two connection sections and a filter layer made of an adsorbent material which covers the filter section with activated carbon toward the first connection section. The first connection section serves as a connection section for fresh air and the second connection section serves as a connection section for the fuel supply system. The filter layer of adsorber material is constructed from a zeolite and / or silica gel and / or aluminum oxide and / or divinylbenzenostyrene material and may be electrically heatable. These adsorber materials have a lower adsorption capacity compared to activated carbon, but are very easily regenerated with air for low-boiling components such as n-butane.

Out WO 01/62367 A1 is a tank ventilation system with at least two adsorptive volumes known, the atmospheric side facing, second adsorptive volume regenerated much faster is considered the main activated carbon filter in the first adsorptive volume. This will u.a. by a finer grain fraction of the application reached reaching adsorbent.

The US Pat. No. 6,540,815 B1 discloses a method for reducing emissions of a tank venting system comprising a first adsorptive volume having an incremental adsorption capacity of between 5% and 50% n-butane in air of greater than 35 g / l and at least one second adsorptive volume having an incremental adsorption capacity of between 5 % and 50% n-butane in air of less than 35 g / l. For a description of the adsorption behavior, only the adsorption isotherm is described there. It is described that, in the case of a flat profile of the adsorption isotherm of the second adsorptive volume, ie of the additional filter element, a particularly good reduction of the total emissions or rapid regenerability can be achieved.

• – die Arbeitskapazität für ein n-Butan/Luftgemisch, die für ein Mischungsverhältnis 50/50 mindestens 1,8 g für das Zusatzvolumen betragen sollte;
• – Länge zu Durchmesser-Verhältnis des Zusatzfilters ≥ 4:1;
• – das Adsorptionsmittel muss möglichst gleichmäßig über den Querschnitt des durchströmten Volumens angebracht sein;
• – der Druckabfall darf bei einem Volumendurchsatz von 70 l/min 140 Pa nicht überschreiten, und sollte so niedrig wie möglich sein;
• – die Restbeladung muss so klein wie möglich – idealerweise nahezu Null – sein. Dies muss insbesondere für sehr geringe Rückspülraten von 150 l bis 200 l gelten.

All known tank ventilation systems thus work with a main activated carbon filter, which is designed for the actual capacity for receiving the fuel vapors, and an additional volume that is sorptively designed such that it is easy to regenerate and thus always flushed free even at very short flush rates of the system. For the sorptive additional volume there are - as has been described above - several embodiments. Crucial for the function in the overall system with the main activated carbon filter are the following parameters:

• - the working capacity of an n-butane / air mixture, which should be at least 1.8 g for the additional volume for a 50/50 mixing ratio;
• - Length to diameter ratio of the additional filter ≥ 4: 1;
• - The adsorbent must be mounted as evenly as possible over the cross section of the volume flowed through;
• - the pressure drop must not exceed 140 Pa at a volume flow rate of 70 l / min, and should be as low as possible;
• - The residual charge must be as small as possible - ideally almost zero. This must be especially true for very low backwash rates of 150 l to 200 l.

Of the known additional filter systems, monolithic honeycomb filters have proven to be advantageous. On the one hand, they have the necessary capacity to absorb the residual emissions from the main asset carbon filters, and they have due to their directional channel structure the required low pressure drop. Such a monolithic honeycomb filter describes, for example, the US 5,914,294 or the DE 101 04 882 A1 , Such honeycomb filters with a cell density of 200 cpi (cells per inch) form the best technical solution so far.

Both in the above mentioned DE 100 49 537 A1 described wound filter as well as in the above-mentioned WO 01/62367 A1 disclosed bed of granules with its particle size distribution have a high pressure drop. This high pressure drop is negatively noticeable in the refueling process, in which both the activated carbon filter and the additional filter are flowed through.

• – Die Kapazität pro Volumen sollte noch größer sein, um die Emissionen aus dem Hauptaktivkohlefilter noch weiter gegen Null zu drücken;
• – die Restbeladung sollte noch geringer sein, um bei einer Annäherung der Emissionen gegen Null keine unnötigen Emissionen aus dem Zusatzfilterelement selbst zu erhalten;
• – die mechanische Stabilität sollte gegenüber den Wabenstrukturen verbessert werden; die Wabenkörper werden mit einer Schaummanschette eingebaut, da sie mechanisch sehr anfällig sind;
• – bei den Wabenstrukturen müssen Dichtungsringe eingesetzt werden, um erhöhte Emissionen aufgrund von Leckagen zu vermeiden;
• – unterschiedliche Filtergeometrien haben bei Einsatz einer Wabenstruktur stets ein gesondertes Werkzeug zur Folge; ideal wäre es, wenn unterschiedliche Formen und Konturen mit einer einzigen Vorrichtung herstellbar wären.

Starting from a granulate bed, a filter with a low pressure drop is obtained by diluting the adsorbents into the available volume by application or incorporation into a three-dimensional support. In this way an open volume flowable is created, resulting in a low pressure drop. However, even the best technical solutions to date have a number of shortcomings:

• - The capacity per volume should be even greater, in order to further reduce the emissions from the main activated carbon filter to zero;
• The residual charge should be even lower, in order to avoid unnecessary emissions from the additional filter element itself when emissions approach zero;
• - The mechanical stability should be improved compared to the honeycomb structures; the honeycomb bodies are installed with a foam collar, as they are mechanically very vulnerable;
• - in the honeycomb structures, sealing rings must be used to avoid increased emissions due to leakage;
• - Different filter geometries always have a separate tool when using a honeycomb structure; It would be ideal if different shapes and contours could be produced with a single device.

The DE 101 50 062 A1 describes a filter device with an activated carbon molding, which has a honeycomb structure, ie, a solution is described here, as a mechanically vulnerable honeycomb body can be installed as an additional filter. However, this solution is based on an additional filter element, which is attached to an activated carbon canister. However, in the design of future activated carbon canister systems, it is assumed that the function of the residual emission filter is integrated into the activated carbon canister.

to Reduction of residual load and increase of working capacity must be on used an adsorbent because of its pore structure specifically for hydrocarbons such as n-butane and pentane at high concentrations in the area receptivity and a very good regenerability with flow through Air has. additionally To these sorptiven properties, the adsorbent has a have high mechanical abrasion resistance and good long-term chemical stability.

The key reason why the honeycomb structure is the best solution so far is its low pressure drop. The special adsorbent must therefore be introduced in a form as a filter behind the main activated carbon bed, which has a very low pressure drop. For this purpose, the adsorbent is applied to a three-dimensional support or introduced in a suitable form in a three-dimensional structure. This can be done using proven technologies that describe such a filter structure. This is, for example, a volume-expanded bulk bed, as used in an activated carbon foam matrix, or a surface-expanded bulk bed, as in the DE 100 26 902 A1 is described. In both cases, it is assumed that a bed is being expanded to a larger volume. This eliminates the disadvantage of high pressure drop. However, in this case the amount of adsorbent per volume is reduced, which results in a lower adsorption capacity than in a packed bed. Finally, a honeycomb structure is also a three-dimensional structure but has a low pressure drop and into which the adsorbents are introduced. However, a further reduction in the amount of adsorbent in the case of honeycomb structures is still due to the binder skeleton.

If a flexible support structure and a flexible binder system is used, then a flexible filter can be designed. This can be self-sealing in a filter housing to the outside. A use of a self-supporting, elastic and introduced under light compression in air supply channels adsorption filter layer of a highly air-permeable support material with a fixed by means of an adhesive adsorbent as a seal and frameless odor and / or pollutant filter is from the DE 195 21 666 known.

Of the Invention is based on the object, the shortcomings of the known technical solutions to further reduce, i. the adsorption capacity per volume to increase, to reduce the emissions to zero, to reduce the residual load, at an approach zero emissions from the auxiliary filter element itself to maintain the mechanical stability compared to that of honeycomb structures to improve, as well as to prevent leaks, and different To be able to produce filter geometries in a single device.

These Task is achieved by the features of claim 1 solved. Preferred training or further education of the filter element according to the invention are in the subclaims characterized.

Due to the fact that the filter element according to the invention is provided with self-sealing in a filter housing having a canister side and an atmosphere side, leaks and thus undesirable emissions from the filter element are avoided in an advantageous manner, and the adsorbent resin provided on the carrier has the advantage of being advantageous mechanically stable, abrasion-resistant adsorbent with a high absorption capacity for hydrocarbons such as n-butane, pentane, hexane or heptane. It is particularly advantageous here if the adsorbent has macroporous adsorber resin particles. Particularly suitable here is the "Lewatit VP OC 1163" from Bayer, Leverkusen, proved. This Lewatit VP OC 1163 has a BET inner surface area of 1500 m ² / g, and has a pore volume of 0.6 to 0.8 cm ³ / g. Lewatit VP OC 1163 is a macroporous cross-linked polystyrene that is available in spherical form. In comparison with known highly activated tank deaeration coals, the said spherical adsorber resin particles are extremely resistant to abrasion and mechanically stable. They can therefore be applied to any known carrier structure with many conventional binder systems.

Lewatit VP OC 1163 is a chemically inert material.

Next The said Lewatit are also other adsorbent resins which have a comparable Pore structure, bulk density and mechanical strength, in the filter element according to the invention can be used as adsorbent.

Further Details, features and advantages will be apparent from the following Description in conjunction with the drawing figures.

It demonstrate:

1 the n-butane working capacity of the inventively used for adsorbent resin,

2 the working capacity for a mixture of pentane, hexane and heptane which has been determined for the adsorbent resin used according to the invention,

3 The n-butane working capacity of Lewatit VP OC 1163 and for a tank venting coal after a pre-charge with pentane, hexane and heptane, wherein the input and output n-butane normalized to the BWC value (butane working capacity) without pre-aging has been,

4 schematically a foam filter block as a self-sealing filter element in a filter housing,

5 one of the 4 similar representation of a filter housing with multiple filter layers,

6 a the 4 and 5 similar schematic representation of a honeycomb structure between two foam layers,

7 a the 4 to 6 similar schematic representation of a canister with an activated carbon bed and a downstream of this foam cone, which is provided with Adsorberharzpartikeln,

8th a the 1 and 2 similar diagram to illustrate the Arbeitkapa of a multilayer filter element similar to that in FIG 5 shown schematically,

9 a schematic representation of another embodiment of the filter element with a shrink sleeve, and

10 a diagram of the n-butane working capacity of the filter element according to 9 ,

The 1 and 2 show the very good sorptive properties of adsorber resin particles. 1 shows the n-butane working capacity, which has been determined according to ASTM D5228-92. The adjusted n-butane concentration was 50% in air. The volume throughput for the loading was 0.1 l / min, and for desorption 22 l / min. It was loaded to a breakthrough of 5000 ppm and then desorbed at said 22 l / min for 15 minutes. Out 1 It can be seen that the adsorbent resin has a very large capacity for n-butane and has virtually no residual charge and can be completely desorbed.

2 illustrates the working capacity for a mixture of pentane, hexane and heptane. It was loaded with a saturated air, which was previously passed through a scrubber with a mixture of the three substances mentioned. The loading was also carried out here at 0.1 l / min and the desorption for 15 minutes at 22 l / min. Again, there is a very good regenerability. The minimum residual charge that results is due to the heptane. Heptane also causes the residual charge when using an activated carbon substantially.

There while a refueling process in addition to n-butane also higher-boiling components up can break through to heptane, will be over The aging on the additional filter always set a residual charge. This aging is carried out by laboratory Loading a canister with additional filter up to a breakthrough adjusted by 2 g of hydrocarbons. So it's crucial that one as possible low residual charge builds up.

In addition to the influence on the emission behavior, the residual charge also has an influence on the capacity of the additional filter, ie the filter element according to the invention. When using an activated carbon, the capacity is significantly more affected after preloading with pentane, hexane and heptane than in the inventive use of adsorbent resin. That is through the 3 which shows the butane working capacity for Lewatit VP OC 1163 and for a known tank venting coal after preloading with pentane, hexane and hepane. It was preloaded with two adsorption-desorption cycles. In 3 the amounts of n-butane added and discharged are each normalized to the BWC (butane working capacity) value without pre-aging. While the Lewatit VP OC 1163 adsorbent resin loses approximately 15% of its capacity, the activated carbon capacity drops to 55%. The activated carbon used was a mesoporous wood activated carbon having an internal surface area of 2000 m ² / g.

When support structures come for the filter element according to the invention all open three-dimensional structures in question. Similarly Is it possible, a flat carrier For example, to coat and pleating or winding or by means of another shaping process into a three-dimensional structure bring to.

When Binder for such a three-dimensional support structure For example, dispersions based on acrylates or polyurethanes in question. This is the carrier impregnated with the dispersion, and subsequently the adsorber resin particles are scattered. Finally done a cure or crosslinking of the binder, for example, by the action of temperature. It has proven to be particularly advantageous if a directly Pressure-sensitive adhesive applied and the carrier is impregnated therewith. Thermoactivatable pressure-sensitive adhesives are particularly advantageous proved. This is the carrier with the binder, which may also be in the form of a dispersion, impregnated and activated under temperature entry. Hereinafter, the carrier becomes, for example loaded in a fluidized bed with the adsorber resin particles or coated.

Exemplary embodiments of the filter element according to the invention are described below:
In a first embodiment of the filter element, a volume-expanded packed bed is produced by means of an open-cell foam. The foam is a commercially available open-cell foam. For example, a polyurethane foam with a cell density of 10 ppi is used. The Adsorberharzpartikel be applied using an acrylate binder on the foam in the form of a monolayer on the webs of the foam. The binder is designed so that the foam retains its elasticity after curing.

Around To fill the interior of a given filter housing homogeneously, more can Layers of polyurethane foam coated and placed in the filter housing become. Another possibility is in the filter housing to introduce a single block of foam, to the interior of the filter housing has adapted contours.

4 schematically shows a sectional view of a foam filter block 1 , the self-sealing filter element in a filter housing 2 is introduced. To cause self-sealing, the diameter of the foam block is 1 for example, 1 mm larger than the inner diameter of the filter housing 2 , Due to the slight compression of the foam block 1 and its elastic restoring force results in a self-sealing of the foam block 1 formed filter element to the inner wall of the filter housing 2 out.

To protect yourself from the lifetime of the foam block 1 possibly releasing spherical Adsorberharzpartikeln the foam block 1 at least at one end face or at its two end faces facing away from each other with a highly air-permeable, for the spherical Adsorberharzpartikel however impermeable cover layer 3 be covered. In 4 is just a cover layer 3 illustrated schematically.

• 1. Der Innenraum des Filtergehäuses wird mit einer Anzahl Lagen des mit Adsorberharzpartikeln beschichteten Schaumstoffes ausgefüllt, wobei die einzelnen Lagen aneinander unmittelbar angrenzen d.h. zueinander benachbart sind.
• 2. Weist das Filtergehäuse eine entsprechende Längenabmessung auf, so können zwischen beschichteten Filterlagen auch unbeschichtete Schaumstofflagen vorgesehen sein. Auf diese Weise sind zusätzliche Diffusionswege realisierbar, die sich vorteilhaft auf die Emissionen auswirken. Der Abstand zwischen den beschichteten Schaumstofflagen kann dabei äquidistant sein oder in Richtung zur Atmosphärenseite hin zunehmen. Ein solcher Aufbau ist in 5 schematisch dargestellt. Dabei sind in dem Filtergehäuse 2' zwischen den mit Adsorberharzpartikeln beschichteten Schaumstofflagen 1' unbeschichtete Schaumstofflagen 4' eingefügt, die eine wesentlich niedrigere Zelldichte besitzen als die mit Adsorberharzpartikeln beschichteten Schaumstofflagen 1'. Die unbeschichteten Schaumstofflagen 4' bilden Abstandhalter. Auch bei dieser Ausführungsform des selbstabdichtenden Filterelementes kann ein- oder beidseitig jeweils eine hoch luftdurchlässige, für die kugelförmigen Adsorberharzpartikel jedoch undurchlässige Abdeckschicht 3' vorgesehen sein.
• 3. Bei der Auswahl der Zelldichte des verwendeten Schaumstoffes ist ein progressiver Aufbau möglich, wobei auf der dem Aktivkohlekanister zugewandten Seite ein Schaumstoff mit einer höheren Zelldichte und auf der zur Atmosphäre weisenden Seite ein Schaumstoff mit einer niedrigeren Zelldichte vorgesehen ist. Auf diese Weise ist es möglich, die Adsorptionsmitteldichte pro Volumen dem Konzentrationsprofil während des Emissionsprozesses anzupassen. Der Durchmesser der kugelförmigen Adsorberharzpartikel ist in diesem Fall an die Zelligkeit des Schaumstoffes angepasst.
• 4. Es ist auch möglich, bewusst die Eigenschaft einer Aktivkohle, bevorzugt Heptan festzuhalten, auszunutzen und die Schaumstofflagen, die dem Aktivkohlekanister zugewandt sind, mit Aktivkohle zu beschichten. Auf diese Weise ist es möglich, dass die Adsorberharzpartikel auf dem Schaumstoff, der der Atmosphärenseite zugewandt ist, deutlich weniger mit Heptan oder höhersiedenden Komponenten belastet werden und hierdurch ihre Arbeitskapazität aufrechterhalten. Anstelle eines Aktivkohle-Schaumstoffes kann selbstverständlich auch eine Aktivkohle-Wabenstruktur eingesetzt werden. Um bei einer solchen Ausbildung die Problematik der Abdichtung und Lagerung der Wabenstruktur zu umgehen, kann die besagte Wabenstruktur zwischen zwei Schaumstofflagen 1'' eingezwängt sein. Der schematische Aufbau für eine solche Ausbildung des selbstabdichtenden Filterelementes ist in 6 dargestellt. Hierbei ist zwischen den beiden beschichteten Schaumstofflagen 1'' ein Aktivkohle-Wabenkörper 5'' eingeklemmt. Der Aktivkohle-Wabenkörper 5'' ist derartig dimensioniert, dass zwischen seiner Außenoberfläche und der Innenwand des Filtergehäuses 2'' nur ein sehr dünner Spalt verbleibt. Mit der Bezugsziffer 3'' ist auch hier eine Abdeckschicht bezeichnet, die dem Schutz vor sich über die Standzeit des Filterelementes von einer der beiden Schaumstofflagen 1'' möglicherweise ablösenden kugelförmigen Adsorberharzpartikeln vorgesehen ist, die einerseits hoch luftdurchlässig ist, aber andererseits für die kugelförmigen Adsorberharzpartikel eine undurchlässige Schicht bildet.

5 schematically illustrates a multilayer construction of the self-sealing filter element. In such a multi-layered structure, the following modifications are possible:

• 1. The interior of the filter housing is filled with a number of layers of coated with adsorbent resin particles foam, the individual layers adjacent to each other directly ie adjacent to each other.
• 2. If the filter housing has a corresponding length dimension, it is also possible to provide uncoated foam layers between coated filter layers. In this way, additional diffusion paths can be realized, which have an advantageous effect on the emissions. The distance between the coated foam layers can be equidistant or increase towards the atmosphere side. Such a structure is in 5 shown schematically. Here are in the filter housing 2 ' between the adsorber resin coated foam sheets 1' uncoated foam layers 4 ' inserted, which have a substantially lower cell density than the adsorber resin coated foam layers 1' , The uncoated foam layers 4 ' form spacers. Also in this embodiment of the self-sealing filter element can on one or both sides in each case a highly air-permeable, for the spherical adsorbent but impermeable cover layer 3 ' be provided.
• 3. In the selection of the cell density of the foam used, a progressive structure is possible, wherein on the activated carbon canister side facing a foam with a higher cell density and on the side facing the atmosphere a foam with a lower cell density is provided. In this way it is possible to adjust the adsorbent density per volume to the concentration profile during the emission process. The diameter of the spherical adsorbent resin particles in this case is adapted to the cellulosity of the foam.
• 4. It is also possible to consciously retain the property of an activated carbon, preferably heptane, and to coat the foam layers facing the activated carbon canister with activated charcoal. In this way, it is possible that the adsorber resin particles on the foam, which faces the atmosphere side, are much less burdened with heptane or higher-boiling components and thereby maintain their working capacity. Of course, instead of an activated carbon foam, it is also possible to use an activated carbon honeycomb structure. In order to avoid the problem of sealing and supporting the honeycomb structure in such an embodiment, the said honeycomb structure can be arranged between two foam layers 1'' be constrained. The schematic structure for such a design of the self-sealing filter element is in 6 shown. Here is between the two coated foam layers 1'' an activated carbon honeycomb body 5 '' trapped. The activated carbon honeycomb body 5 '' is dimensioned such that between its outer surface and the inner wall of the filter housing 2 '' only a very thin gap remains. With the reference number 3 '' Here, too, a cover layer is referred to, the protection in front of him over the life of the filter element of one of the two foam layers 1'' possibly releasing spherical Adsorberharzpartikeln is provided which is highly permeable to air on the one hand, but on the other hand forms an impermeable layer for the spherical Adsorberharzpartikel.

The use of a compressible and loaded with adsorber resin particles or coated foam carrier has another advantage: You can use this material directly as a covering layer for an activated carbon bed. It is possible to adapt to the inner contours of the Filtergehäu ses or a canister to realize. Likewise, it is for example possible to obtain a gradation of Adsorberharzpartikelmenge per volume between the activated carbon bed and the atmosphere side of the filter element by a frusto-conical or truncated pyramidal foam carrier in a correspondingly tapered canister outlet. Such an embodiment of the latter type is schematically shown in FIG 7 shown. Here is the activated carbon bed 22 a foam cone loaded with adsorber resin particles 33 downstream. The foam cone 33 is in a conically tapering section of the filter housing between the activated carbon bed 22 and a transition 44 provided to the atmosphere side. The conical design of the foam cone 33 acts on a flow in the desorption direction, which is indicated by the arrow 55 is indicated, in addition, as a diffuser, causing the activated carbon bed 22 is even more desorbable.

following become two concrete embodiments of the filter element according to the invention described:

Embodiment 1

in this connection Eight layers of polyurethane foam are provided, each one have a thickness of 10 mm and a cell density of 10 ppi. Of the Diameter of the individual foam layers is 40 mm. On these eight layers Polyurethane foam is one with the help of an acrylate binder Amount of 12 g of the adsorbent resin Lewatit VP OC 1163 applied. The eight foam layers coated with Lewatit VP OC 1163 are in a cylindrical filter housing used. The lowest layer is with a highly air-permeable, for the spherical Adsorberharzpartikel but impermeable Fleece covered.

As described above, the n-butane working capacity was determined on the auxiliary filter element produced in this way. The result is in 8th shown in a diagram. How out 8th it can be seen, has the thus realized additional filter elements practically no residual load and a n-butane working capacity of 3.6 g.

It was also recorded the pressure drop at a flow rate of 70 l / min. It has been shown that the foam filter in the filter housing a additional Differential pressure of 130 Pa builds up.

Next the application of the adsorbent resin particles to a three-dimensional support structure it is also possible the adsorbent in the form of a long cylinder in one Hose or pipe piece to fix. Each activated carbon canister has on the atmosphere side a connection that over a hose to an on-board diagnostic system of a motor vehicle connectable or is connected.

ever Depending on the vehicle type or installation situation can be a sufficiently long line section result, in addition as installation volume for an adsorbent is usable. Since the differential pressure through the Insertion of an adsorbent must not be increased, the inner diameter must be of the introduced into the hose or the pipe piece filter element i.e. Adsorber resin cylinder at least the diameter of the time own used hose or pipe pieces. The following second embodiment describes such a tubular Filter element.

Embodiment 2:

Here, adsorbent resin of the type VP OC 1163 with the aid of in the DE 100 26 902 described method applied to a nonwoven fabric. The Adsorberharzpartikelmenge is 450 g / m ² . From the thus-prepared nonwoven fabric, a tape was cut out and rolled into a long cylinder having an inner diameter of 12 mm and a length of 300 mm. For attachment of fittings, the cylinder was placed in a shrink tube and shrunk the cylinder with the fittings in the shrink tube. In this way, results in a flexible hose with a Adsorberharzpartikelmenge of 6 g.

A realized in this way filter element is in 9 shown schematically. In this filter element, the shrink sleeve provides 222 at the same time a gas-tight outer skin, in which the carrier fleece 333 including adsorber resin 444 inserted and with the fittings 111 is tightly connected.

The n-butane working capacity for the filter element according to the second embodiment is shown in FIG 10 shown. From this diagram it can be seen that, in contrast to a bed or a foam formation, a slight residual charge builds up. This is because during desorption, the adsorbent particles that are on the outside of the nonwoven fabric come from the heat shrink sleeve 22 are covered and therefore are not flowed around. The desorption of the last-mentioned adsorber particles is determined primarily by the diffusion of the n-butane to the already leached, further inside Adsorberharzpartikeln.

The disadvantage of the multilayer coating can of course be eliminated by a monolayer with simultaneous extension of the tube again. Thus, a bag filter with a circulation of 110 g / m ^{2 of} the adsorbent resin of embodiment 2 and a total length of 900 mm no residual charge for n-butane more.

In the following table, the results for the working capacity and the residual charge for n-butane and for the differential pressure Ap, which is additionally constructed in a standard Prüfkapsel, for the two embodiments above and for an activated carbon honeycomb body according to the above-mentioned US 5,914,294 made, summarized:

there BWC means the butane working capacity.

Further embodiments with a flat carrier arise, for example, by pleating and a star-shaped arrangement or by a winding body with spacers.

The Adsorption performance is reduced with a temperature increase 42 ° C slightly. Around To compensate for this reduction, it is possible to add PCM's (Phase Change Materials) to the carrier. apply before the Adsorberharzpartikel be applied. Preferred are PCMs, their phase transition between 36 ° C and 42 ° C have. This is a similar one Effect can be achieved, as with materials that have a high heat capacity, as described in the prior art.

at Application of a foam as a carrier, it is advisable, first To coat the foam with a layer of PCM's and then the Apply Adsorberharzpartikel on the PCM layer. Similarly is it possible that PCM's in the binder, the for the Adsorberharzpartikel is applied to the carrier, directly to disperse.

Also at the tubular Training, it is appropriate to the carrier first the PCM layer and then the adsorber resin particle layer applied. By making up a hose results shielding the adsorber layer by the PCM layer, what an ideal thermal insulation represents.

Instead of the resin on the carrier with the help of a binder, you can also directly the resin particles mix with fusible fibers, form into a surface and briefly over the Heat the melting point of the fibers. Particularly suitable for this are bicomponent fibers.

• – Direkte Extrusion in eine elastische Wabenstruktur.
• – Herstellung einer Fläche mit anschließender Strukturierung. Die strukturierte Fläche wird anschließend aufgerollt (ähnlich einer Wellpappenstruktur).

It is ideal if the adsorbent is produced in the form of an elastic, self-supporting structure. So you can bring the adsorbent resin with an elastic binder with a suitable shaping process in a molding. In addition, you can bring the PCM's in the shaping process equal to the moldings. The shaping process must be coordinated with the type of binder used. Here are the following methods conceivable:

• - Direct extrusion into an elastic honeycomb structure.
• - Production of a surface with subsequent structuring. The structured surface is then rolled up (similar to a corrugated cardboard structure).

• – Ein plissierter Filter aus einem mit dem Harz beschichteten Vlies.
• – Ein wie im Ausführungsbeispiel 1 beschriebener Schaum beschichtet mit dem Harz. Hier würde man nur eine Lage in den Abmaßen des Strömungsquerschnittes des Motorzuluftfilters einsetzen.
• – Eine Lage eines solchen Schaumes umhüllt mit einer noch luftdurchlässigen aber für die Absorberharzpartikel undurchlässigen Abdeckschicht als passiv umströmtes Filterelement.

Due to its sorptive properties, the filter element described here can not only be used as an additional filter for a tank ventilation filter, but it is also very well suited as carbon Hydrogen trap in the intake tract of internal combustion engines. There, after switching off the engine via open valve positions, hydrocarbons (gasoline vapors) can escape via the intake tract of the engine and also contribute to the emissions of the car. The embodiments described in this application can be used after adaptation to the geometric conditions both as a flowed through and as a filter units flow around in the region of the engine intake filter in the intake of an internal combustion engine. Possible embodiments are here:

• - A pleated filter made of a resin-coated nonwoven fabric.
• - A foam as described in Example 1 coated with the resin. Here one would use only one layer in the dimensions of the flow cross-section of the engine air filter.
• - A layer of such a foam enveloped with a still air-permeable but impermeable to the absorber resin cover layer as a passively flow around filter element.

Claims (40)

Filter element for use in a vehicle emitting emissions of hydrocarbons, wherein the hydrocarbons are reversibly bound, in particular additional filter for a tank vent filter, for an engine air intake o. The like., Wherein the filter element comprises a carrier with an adsorbent, characterized in that the filter element in a Filter housing, which has a hydrocarbon emission source facing and one facing the atmosphere side, is arranged, and that the adsorbent provided on the carrier Adsorberharzpartikel. Filter element according to claim 1, characterized in that that the filter element provided in the filter housing self-sealing is. Filter element according to claim 1, characterized in that the adsorbent macroporous Adsorberharzpartikel has. Filter element according to claim 1 or 3, characterized the adsorber resin particles are spherical and have a particle diameter between ≥ 0.1 mm and ≤ 2 mm have. Filter element according to claim 4, characterized in that the particle diameter is between ≥ 0.3 mm and ≤ 0.8 mm. Filter element according to claim 5, characterized in that the particle diameter is between ≥ 0.4 mm and ≤ 0.6 mm. Filter element according to one of claims 1 to 6, characterized in that the pore volume of the Adsorberharzpartikel ≥ 0.6 cm ³ / g. Filter element according to one of claims 1 to 7, characterized in that the BET surface area of the adsorbent resin particles ≥ 1000 m ² / g. Filter element according to one of claims 1 to 8, characterized in that the water content of the Adsorberharzpartikel ≤ 65%. Filter element according to one of claims 1 to 9, characterized in that the adsorbent carrier is a sheet, the like in the filter housing is arranged that it flows through or around it becomes. Filter element according to one of claims 1 to 9, characterized in that the adsorbent carrier is a three-dimensional open-pore The structure is in the filter housing is arranged such that it is flowed through. Filter element according to claim 11, characterized in that that the three-dimensional open-pored structure as a support block is trained. Filter element according to claim 11, characterized in that that the three-dimensional open-pored structure has a number of carrier layers having. Filter element according to claim 13, characterized in that that the carrier layers immediately adjacent to each other. Filter element according to claim 13, characterized in that that the carrier layers are spaced from each other by open-pore spacing layers. Filter element according to claim 15, characterized in that that the spacer layers have a cell density that is smaller as the cell density of the carrier layers. Filter element according to one of claims 13 to 16, characterized in that the cell density of the carrier layers from the canister side to the atmosphere side of the filter housing decreases. Filter element according to claim 12, characterized in that that the support block is formed by an open-cell foam whose porosity 5 bis 25 ppi, preferably 8 to 15 ppi, more preferably 10 ppi. Filter element according to one of claims 13 to 17, characterized in that the respective carrier layer is formed by an open-cell foam whose porosity 5 bis 25 ppi. Filter element according to claim 18 to 19, characterized that the particle diameter of the spherical Adsorberharzpartikel adapted to the cell density of the open-cell foam. Filter element according to one of claims 1 to 20, characterized in that the carrier before its loading with coated with the adsorber resin particles with phase change material (PCM) becomes. Filter element according to claim 21, characterized in that that the phase change material a phase transition between 35 ° C and 42 ° C has. Filter element according to one of claims 1 to 22, characterized in that in the filter housing adsorber foam with Activated carbon foam and / or combined with at least one activated carbon honeycomb body is. Filter element according to claim 11, characterized in that that the Adsorberharzpartikel on three-dimensional open-pored structure of the adsorbent carrier are fixed by means of a pressure-sensitive adhesive. Filter element according to claim 24, characterized that the pressure-sensitive adhesive of a thermally activated pressure-sensitive adhesive is formed. Filter element according to claim 24 to 25, characterized that after loading the three-dimensional open-pored structure with the adsorber resin particles still free, residual adhesive surface with powdery Adsorber resin or powdered Activated carbon is occupied. Filter element according to one of claims 1 to 26, characterized in that the filter housing forms a canister, in which a Adsorberpartikelschüttung is provided, the at least one side with a gas-permeable adsorptive Cover is covered. Filter element according to claim 27, characterized that the cover is formed by an open-pored foam layer is, which is loaded with Adsorberharzpartikeln. Filter element according to claim 27 to 28, characterized that the atmosphere side Cover is tapered towards the atmosphere. Filter element according to claim 10, characterized in that the flat adsorber carrier is rolled tubular and coated with an edition of 100 to 600 g / m2, preferably 200 to 400 g / m ² , Adsorberharzpartikeln. Filter element according to claim 1, characterized in that the Adsorberharzpartikel mixed with fusible fibers and to a surface element be formed, the momentary above the melting point of the fibers heated and then chilled becomes. Filter element according to claim 31, characterized in that that the fusible fibers are formed by bicomponent fibers. Filter element according to claim 1, characterized in that the filter element is formed by an extruded honeycomb structure is that contains the Adsorberharzpartikel with a binder. Filter element according to claim 31 or 33, characterized characterized in that the Adsorberharzpartikel before molding the filter element (extrusion of a honeycomb structure or training of a surface element) with a phase change material (PCM). Filter element according to claim 31 or 32, characterized characterized in that the surface element as a structured surface element is formed, which is rolled up into a cylinder. Filter element according to claim 1, characterized by a pleated filter body from a nonwoven material coated with adsorber resin particles is and a hydrocarbon trap in the intake of an internal combustion engine forms. Filter element according to claim 1, characterized by a three-dimensional open-pored carrier structure containing adsorber resin particles is coated and a flow-through monolayer is used as hydrocarbon traps in the intake tract of an internal combustion engine forms. Filter element according to claim 37, characterized that the three-dimensional open-pored support structure has an inflow side and a downstream side has, wherein provided at least on the downstream side a cover layer is that permeable to air but for the Adsorberharzpartikel is impermeable. Filter element according to claim 38, characterized that also on the upstream side the three-dimensional open-pored carrier structure a cover layer is provided. Filter element according to claim 38 or 39, characterized characterized in that the filter element is a passively flowed around filter medium forms.