BACKGROUND OF THE INVENTION

The invention relates to a sorption device and to a sorption system for filtering evaporation emissions from a fuel tank.

The sorption device of this kind and/or the sorption system is usually used to filter substances, in particular harmful substances, out of the evaporation emissions of a fuel tank, the evaporation emissions in particular escaping via an air supply and removal path of the fuel tank. The evaporation emissions to be filtered should flow through the filter such that as much as possible of the substance to be filtered out is sorbed by the sorption device and/or the sorption system. A filtering performance of the sorption device and/or of the sorption system should be as high as possible, for example as much hydrocarbon as possible should be filtered out of the evaporation emissions, in order to minimize or eliminate the environmental impact. Furthermore, the sorption device and/or the sorption system should assist in complying with legal provisions, in particular emission regulations.

SUMMARY OF THE INVENTION

Against this background, an object of the present invention is to provide an improved sorption device and/or an improved sorption system, in particular with an increased sorption rate.

This object is solved by the subject matter of the relevant independent claim.

An aspect relates to a sorption device for filtering evaporation emissions from a fuel tank, comprising a vessel for at least partially filtering evaporation emissions from the fuel tank, it being possible to connect a first opening of the vessel to an air removal path of the fuel tank and a second opening of the vessel opening out into the atmosphere. A middle annular space is arranged in the vessel between a radial outer boundary of the middle annular space that extends all the way around in the circumferential direction and a radial inner boundary thereof that extends all the way around in the circumferential direction and that is radially inwardly spaced apart from said outer boundary. A first annular space is formed between a radial inner surface of a fluid-tight outer shell of the vessel, which outer shell extends all the way around in the circumferential direction, and the radial outer boundary of the middle annular space that is radially inwardly spaced apart therefrom. Moreover, a sorbent, in particular adsorbent, material is arranged in the middle annular space. Evaporation emissions from the fuel tank are guided through the first opening into the first annular space, through the sorbent material into a central space of the vessel in the radial direction, and through the second opening directly or indirectly into the atmosphere or into another sorption device.

An advantage of the present invention is that, by guiding the evaporation emissions through successive spaces of different designs, the substances contained in the evaporation emissions are mixed more thoroughly, the evaporation emissions in particular being homogenized. This prevents areas having a higher concentration of a substance to be filtered out of the evaporation emissions, for example hydrocarbons, which could otherwise only be sorbed in part. Therefore, by means of the configuration according to the invention, a sorption rate can be increased, which, with regard to the substance to be filtered out for example the hydrocarbons contained in the evaporation emissions results in an improved filtering performance of the sorption device and/or of the sorption system.

The sorption device may be a device for at least partially filtering substances and/or particles out of a fluid. The fluid may be a gaseous medium, in particular a mixture of air and gaseous fuel, for example evaporation emissions from a fuel tank. In particular, the sorption device may be part of an activated charcoal canister.

The fuel tank may be a tank or container, for example a canister, for storing fuel and may be stationary or provided in a motor vehicle comprising an internal combustion engine.

The air removal path of the fuel tank may for example be a closed line for guiding the evaporation emissions out of the fuel tank into the atmosphere, it being possible to arrange one or more filter elements and/or sorption devices in the air removal path.

The vessel may contain a plurality of spaces, in particular annular spaces, which serve to guide the evaporation emissions around and/or through. In particular, guide elements such as channels, chambers and/or deflection plates or deflection bodies may be provided for this purpose. A deflection plate may for example be made from metal, plastics material, fiber material or combinations thereof; the term “plate” should simply be understood to mean “sheet-like”.

The vessel may have an approximately circle-shaped or polygonal cross-section, for example an elliptical, circular or rectangular cross-section.

The first opening of the vessel may be designed for more simple connection to the air removal by means of a quick coupling, for example a bayonet fitting and/or an engaging means.

The second opening of the vessel may be provided with a removable cover in order to prevent liquid and/or solid foreign matter from entering the vessel. The cover may for example be designed having a removable dust cap, which covers an outlet of the cover to the atmosphere but which allows for a fluid connection between the second opening and the atmosphere.

The radial inner surface of a body may be a surface formed on the inside, in the radial direction, of the body. In particular, the radial inner surface of the, for example, approximately hollow-cylindrical outer shell of the vessel is a surface formed on the inside, in the radial direction, of the outer shell, i.e. more or less the inner lateral surface of the approximately hollow-cylindrical outer shell.

Accordingly, the radial outer surface of a body is a surface formed on the outside, in the radial direction, of the body. In particular, the radial outer surface of a, for example, approximately hollow-cylindrical inner shell of the vessel is a surface formed on the outside, in the radial direction, of the inner shell, i.e. the lateral surface of the approximately hollow-cylindrical inner shell.

The relevant annular space may be designed as an approximately ring-shaped space in the vessel, more or less as an approximately hollow-cylindrical negative shape. The relevant annular space, depending on the desired function thereof for guiding the evaporation emissions around or through, may be delimited at least in portions by a fluid-tight wall or a wall that is permeable at least in parts to the evaporation emissions.

The sorbent material may comprise adsorbent material at least in part. For example, the sorbent material may contain activated carbon, activated charcoal, clay, zeolite, porous polymer, porous alumina, porous silica, titanium dioxide, cerium dioxide and/or combinations thereof. A fluid stream, for example an air stream, may be directed from the second opening of the vessel to the first opening of the vessel in order to clean the sorbent material of caked-on substances, for example.

An axial direction may be a direction in an extension of a length of a component. In the case of a, for example, approximately cylindrical vessel, the axial direction is oriented approximately in parallel with a generatrix or the longitudinal axis of the vessel.

A radial direction may be oriented perpendicularly to the axial direction. In the case of the, for example, approximately cylindrical vessel, the radial direction is oriented so as to coincide with the radius of the approximately cylindrical vessel. In the case of a, for example, hollow-cylindrical sorbent material designed as a molded body, the radial direction extends in the direction of the wall thickness of the approximately hollow-cylindrical sorbent material designed as a molded body.

Accordingly, a circumferential direction may be a direction in an extension of the circumference of the component.

Within the context of the present invention, the terms “outer” and “inner” and the like used in the following should be understood to mean that an, in particular idealized or imaginary, central point is an innermost point. A region external to this is an, in particular idealized or imaginary, circumferential region. A point or region that is referred to as being further out than another point or region is therefore further out in the radial direction from the central point toward the circumferential region than the other point or region.

The sorbent material may be designed as a granular material and/or as a molded body that is permeable to the flow in particular in the radial direction thereof, it being possible for the molded body to be a self-supporting molded body. For example, the molded body may be approximately hollow-cylindrical. The sorbent material may therefore be poured into a cavity and/or received in the vessel in any desired design in solid form. This ensures a high degree of design freedom, in particular when designing the vessel.

The molded body may be axially held, in particular mounted, in the second annular space by means of at least one spacer ring.

Alternatively or additionally, the molded body may consist at least in part of sorbent material.

Advantageously, the sorbent material may be designed at least in part as adsorbent material. Therefore, the sorbent material can be cleaned more easily, in particular of caked-on sorbate, and can be used multiple times, which increases the useful life of the sorbent material and thus the maintenance interval of the sorption device.

Alternatively or additionally, the sorbent material may be designed at least in part as absorbent material. Therefore, the suitable sorbent material can be selected or combined from various sorbent materials depending on the application.

In particular, the radial outer boundary of the middle annular space may be designed as a radial outer surface of the sorbent material designed as a molded body. Moreover, the radial inner boundary of the middle annular space may be designed as a radial inner surface of the sorbent material designed as a molded body.

Alternatively, the radial outer boundary of the middle annular space may be designed as a radial outer surface of a first slotted wall that extends all the way around in the circumferential direction. Moreover, the radial inner boundary of the middle annular space may be designed as a radial inner surface of a second slotted wall that extends all the way around in the circumferential direction, the second slotted wall being radially inwardly spaced apart from the first slotted wall.

By virtue of this configuration, an extension of the middle annular space and/or of the sorbent material designed as a molded body in the radial direction can be handled in a flexible manner, depending on the design.

In particular, a second annular space can be formed between a radial inner surface of the first slotted wall and a radial outer surface of the second slotted wall, it being possible for the sorbent material to be designed as a granular material and/or as a molded body in the second annular space.

The outer boundary and/or the inner boundary of the middle annular space may be physical or imaginary delimitations of the middle annular space. For example, in the case of a sorbent material designed as a granular material, the granular material may be supported by a wall arranged radially outward therefrom and a wall arranged radially inward therefrom, in particular by the slotted walls described above. In contrast, in the case of the sorbent material designed as a self-supporting molded body, supporting walls can be dispensed with entirely, however it is also possible for the molded body to be arranged between supporting walls like the granular material.

Alternatively or additionally, the sorbent material may be designed as a coating of at least one surface on the inside of the vessel. For example, the coating may be formed at least on the radial inner surface of the first slotted wall and/or at least on the radial outer surface of the second slotted wall. In this way, the level of design freedom can be increased even further with regard to the accommodation of the sorbent material. In particular, a surface between the slots may also be coated with the sorbent material.

The slotted wall may be designed as a wall that is permeable at least in parts to the evaporation emissions from the fuel tank, for example as a wall that is porous at least in parts and/or perforated at least in parts. In particular, one or more perforations that may be designed to extend in the axial direction at least in part and/or in the circumferential direction at least in part may be formed as a hole or slot in the slotted wall. For example, a plurality of slots may be formed over an entire circumference of the slotted wall and extend over an entire axial length of the slotted wall. Alternatively, a plurality of slots may be formed over part of the circumference of the slotted wall. As another alternative, a plurality of slots may extend over part of the axial length of the slotted wall. In particular in the case of slots that extend continuously in the circumferential direction, the slots may be interconnected and thus held together by means of connecting webs.

A filter element comprising sorbent material may be arranged in the central space. Therefore, in addition to the sorbent material already provided, a filter element comprising additional sorbent material can also be provided, as a result of which the filtering performance of the sorption device can be further increased.

In other words, a filter element comprising sorbent material may be arranged downstream of the sorbent material, viewed in the direction of flow of the evaporation emissions from the fuel tank. Alternatively or additionally, a filter element comprising sorbent material may be arranged upstream of the sorbent material, viewed in the direction of flow of the evaporation emissions from the fuel tank.

In particular, the evaporation emissions from the fuel tank may be guided along the filter element and/or through the filter element to the second opening of the vessel. In particular, more of the above-mentioned guide elements may be provided for this purpose.

The filter element may be coated at least in parts with sorbent material or may be made at least in parts of sorbent material. For example, the filter element may comprise a large number of axially formed channels, it being possible for the filter element to have a honeycomb structure in cross-section. In particular, inner walls of the channels may be coated at least in parts with sorbent material.

In particular, an insert that comprises a fluid-tight outer wall that extends all the way around in the circumferential direction may be arranged in the vessel. Furthermore, the outer wall of the insert may be arranged in the first annular space and an outer annular space may be formed between a radial inner surface of the outer shell of the vessel and a radial outer surface of the outer wall of the insert. The outer annular space may be radially outwardly spaced apart from the first annular space and fluidically connected to the first annular space via an outer annular gap that extends all the way around in the circumferential direction. In this way, the evaporation emissions can be guided around inside the vessel prior to being guided through the sorbent material and thus mixed thoroughly in order to increase the sorption rate of, for example, hydrocarbons contained in the evaporation emissions by means of the sorbent material.

The insert may comprise a fluid-tight insert base on the axial end portion thereof facing the first opening of the vessel, it being possible for the outer wall of the insert to be formed on said insert base so as to protrude therefrom in the axial direction. Furthermore, the insert may be designed to be open on the axial end portion thereof facing the second opening of the vessel. By virtue of this configuration, the evaporation emissions can be more easily guided around inside the vessel and thus mixed more thoroughly.

In particular, the central space may be radially outwardly delimited by a fluid-tight inner shell of the vessel that extends all the way around in the circumferential direction, it being possible for the inner shell to be radially inwardly spaced apart from the second slotted wall. Furthermore, an inner annular space may be formed between a radial inner surface of the second slotted wall and a radial outer surface of the inner shell.

Alternatively, the central space may be radially outwardly delimited by a fluid-tight inner shell of the vessel that extends all the way around in the circumferential direction, it being possible for the inner shell to be radially inwardly spaced apart from the middle annular space, in particular the radial inner boundary of the middle annular space. Moreover, an inner annular space may be formed between the radial inner boundary of the middle annular space and a radial outer surface of the inner shell.

This configuration may further help to guide the evaporation emissions around more easily inside the vessel and thus mix same more thoroughly.

The central space may be designed to be open on the axial end portion thereof facing the second opening of the vessel. Furthermore, the central space may be delimited on the axial end portion thereof facing the first opening of the vessel by a slotted inner shell base of the inner shell. By virtue of this configuration, too, the evaporation emissions can be more easily guided around inside the vessel and thus mixed more thoroughly.

In particular, the insert may comprise a fluid-tight inner wall that extends all the way around in the circumferential direction and that is radially inwardly spaced apart from the outer wall of said insert. Furthermore, the inner wall of the insert may be arranged in the inner annular space and a third annular space may be formed between the radial inner surface of the second slotted wall and a radial outer surface of the inner wall of the insert. Alternatively, the third annular space may be formed between the radial inner boundary of the middle annular space and a radial outer surface of the inner wall of the insert. Moreover, the third annular space may be radially outwardly spaced apart from the inner annular space and fluidically connected to the inner annular space via an inner annular gap that extends all the way around in the circumferential direction. This configuration is also suitable for guiding the evaporation emissions around more easily inside the vessel and thus mixing same more thoroughly.

The central space and the annular spaces may be formed concentrically to one another. This configuration may promote a uniform distribution of the sorbent material and the evaporation emissions inside the vessel.

The inner wall of the insert may be formed on the insert base so as to protrude therefrom in the axial direction. In particular, the insert may be formed in one piece by means of the inner wall and/or the above-mentioned outer wall of the insert, which is also formed on the insert base so as to protrude therefrom in the axial direction. As a result, the manufacture of the insert and/or the handling thereof, in particular when installing the insert in the vessel, can be simplified.

In particular, the first slotted wall, the second slotted wall and the inner shell, by means of the relevant axial end portion thereof facing the second opening of the vessel, may be formed, in particular integrally, on a fluid-tight vessel lid of the vessel so as to protrude therefrom in the axial direction. The first slotted wall and the second slotted wall may each comprise a free end on the relevant axial end portion thereof facing the first opening of the vessel. As a result, the manufacture of the vessel lid with the slotted walls and the inner shell, and/or the handling thereof, in particular when installing the vessel lid in the vessel, can be simplified.

The free ends of first slotted wall and the second slotted wall may touch the insert in the region of the insert base. By virtue of this configuration, the second annular space can be separated from the rest of the vessel by means of the slotted walls and the, in particular granular, sorbent material can be held in the second annular space. Of course, the slots in the slotted walls are dimensioned such that the sorbent material designed as granular material cannot pass through the slots. For example, a distance between the slots may be less than a grain size of the granular material.

As an alternative or in addition to the above-described slots in the first slotted wall and second slotted wall, the walls of the second annular space may comprise holes or comprise a sieve mesh or a nonwoven fabric at least in parts.

In particular, if the sorbent material also referred to as sorbent or sorption medium is designed as a self-supporting molded body, for example approximately hollow-cylindrical, it is possible to dispense with the slotted walls of the second annular space.

In this case, the self-supporting molded body can be arranged in the middle annular space, the middle annular space being formed between the inner annular space and the outer annular space, viewed in the radial direction. The self-supporting molded body may be arranged and/or releasably fastened centrally in the middle annular space, in particular by means of a centering means.

Another aspect relates to a sorption system for at least partially filtering evaporation emissions from a fuel tank, comprising a sorption device according to any one of the preceding claims, a pre-vessel for at least partially filtering evaporation emissions from a fuel tank being arranged upstream and/or downstream of the sorption device.

The advantages of the sorption system are analogous to the features and advantages of the sorption device mentioned above.

In the following, exemplary embodiments of the sorption device according to the invention will be explained in greater detail based on the drawings. Of course, the present invention is not restricted to the exemplary embodiments described in the following, and individual features thereof can be combined with other exemplary embodiments.

