Activated Carbon Filter Having Barrier Layer

Abstract

An activated carbon filter for reducing hydrocarbon emissions, includes a plurality of channels, the channels being suitable for the flow of gases therethrough and at least part of the surface of the channel walls having activated carbon for absorbing and/or adsorbing substances, in particular hydrocarbons; and a filter peripheral wall on the outer periphery of the activated carbon filter; wherein the filter peripheral wall comprises a barrier layer, in particular in the form of a coating on the outer surface of the filter peripheral wall, preventing or at least significantly reducing the penetration, in particular the diffusion, of gases and/or substances, in particular hydrocarbon-containing gases, through the filter peripheral wall.

Claims

1. An activated carbon filter for reducing hydrocarbon emissions, comprising: a plurality of channels, wherein the channels are suitable to be flown through by gases, wherein at least part of the surface of channel walls which define said channels has a material for absorbing and/or adsorbing substances; and a filter peripheral wall on an outer periphery of the activated carbon filter; wherein the filter peripheral wall comprises a barrier layer, which at least significantly reduces penetration of gases and/or substances, through the filter peripheral wall.

2. The activated carbon filter according to claim 1, wherein the channel walls and the filter peripheral wall include activated carbon; and wherein the filter peripheral wall comprises a barrier layer in the form of a coating.

3. The activated carbon filter according to claim 2, wherein the activated carbon filter has activated carbon over at least a partial area of the coating.

4. The activated carbon filter according to claim 1, wherein the channel walls and the filter peripheral wall include a carrier material; and wherein the carrier material of the filter peripheral wall serves as a barrier layer, and the carrier material at least partially has an activated carbon coating.

5. The activated carbon filter according to claim 4, wherein only an inner side of the carrier material which at least partially defines the channels has an activated carbon coating.

6. The activated carbon filter according to claim 4, wherein the carrier material of the filter peripheral wall has activated carbon on an outer wall of the activated carbon filter at least over a partial area.

7. The activated carbon filter according to claim 1, wherein the activated carbon filter is substantially cylindrical; and wherein the channels are aligned in an axial direction of the filter.

8. An activated carbon filter system, as part of a fuel vapor buffer device for reducing hydrocarbon emissions, comprising: at least one activated carbon filter according to claim 1; a housing for accommodating the at least one activated carbon filter; at least one sealing device for tightly closing a gap space between an inner wall of the housing and the filter peripheral wall of the at least one activated carbon filter, so that a penetration of gases and/or substances into the gap space is at least significantly reduced.

9. The activated carbon filter according to claim 1, wherein: said material is activated carbon; said substances are hydrocarbons; and said penetration is diffusion; and said gases and/or substances are hydrocarbon-containing gases.

10. The activated carbon filter according to claim 4, wherein the carrier material is one of: plastic or ceramic.

11. The activated carbon filter system according to claim 8, wherein the gases and/or substances are hydrocarbon-containing gases.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1 shows an activated carbon filter according to a first aspect of the invention;

[0026] FIG. 2 shows a cross section of an activated carbon filter according to a first aspect of the invention;

[0027] FIG. 3 shows a part of a fuel vapor buffer device comprising two activated carbon filter systems according to a second aspect of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

[0028] FIG. 1 shows a preferred embodiment of an activated carbon filter 1 according to a first aspect of the invention. The activated carbon filter 1 has a cylindrical shape and comprises channels 2, wherein a plurality of the channels 2 has a square cross section. The filter peripheral wall 7 of the activated carbon filter 1 encloses the channels 2. In this preferred embodiment of the activated carbon filter 1, the filter peripheral wall 7 and the channel walls 3 consist of a carrier material (not shown), which is preferably completely and throughout covered with an activated carbon coating. The carrier material of the filter peripheral wall 7 serves as a barrier layer, which prevents or reduces penetration or diffusion of hydrocarbon-containing gases or hydrocarbons through the filter peripheral wall 7.

[0029] Alternatively, only the inner walls of the channels 2 may have, at least in some part(s), an activated carbon coating substantially throughout. Preferably, an activated carbon coating can additionally be applied to the outer surface of the carrier material of the filter peripheral wall 7 at least in some part(s), wherein the areas that are in contact with a sealing means when the activated carbon filter 1 is mounted in a housing 9 do not have activated carbon.

[0030] FIG. 2 shows a cross section of a further preferred embodiment of an activated carbon filter 1 according to a first aspect of the invention. The activated carbon filter 1 has a round cross section and rectilinear channels 2, wherein a large number of the channels 2 has a square cross section. The activated carbon filter 1 shown has a filter peripheral wall 7 and channel walls 3, which consist of activated carbon or a material containing activated carbon. The filter peripheral wall 7 of the activated carbon filter 1 also has a coating 8, so that the coating 8 forms the outside of the activated carbon filter 1. The coating 8 covers the entire area and prevents or reduces penetration or diffusion of hydrocarbon-containing gases or hydrocarbons through the filter peripheral wall 7.

[0031] Preferably, the filter peripheral wall 7 additionally and at least in some part(s) has activated carbon, wherein the areas that are in contact with a sealing means when the activated carbon filter 1 is mounted in a housing 9 do not have activated carbon.

[0032] FIG. 3 shows a part of a fuel vapor buffer device comprising two activated carbon filter systems 10 according to a second aspect of the invention. Each of the activated carbon filter systems 10 has a housing 3, an activated carbon filter 1, two sealing devices 4 completely enclosing the activated carbon filter 1, and a gap space 5 between the housing inner wall 6 of the housing 3 and the activated carbon filter 1. The activated carbon filter systems 10 shown are connected to each another such that the activated carbon filters 1 of the activated carbon filter systems 10 are successively flown through by a supplied gas or air stream.

[0033] The fuel vapor buffer device preferably comprises at least a further activated carbon filter system, which is preferably located between tank and the activated carbon filter systems 10 shown, so that fuel vapors from the tank first have to pass the further activated carbon filter system (not shown) before they flow into the filter systems 10 shown. In such a preferred arrangement, one of the activated carbon filter systems 10 according to the invention is in direct contact with the atmosphere (left filter system 10 in FIG. 3). As a result, hydrocarbons located in the gap space 6 of the activated carbon filter system 10 can reach the atmosphere in an unfiltered manner due to a leak in the seal of the upper sealing device 4.

[0034] The fuel vapor buffer device shown is flushed through with flushing air in the reverse direction during a flushing process. The filter systems 10 shown are first flushed through before the flushing air flows through the further filter system, not shown, and is finally admixed with the combustion air of the engine. Due to the sealing devices 4, the gap space 5 is not flown through by the flushing air, so that the gap space 5 is not cleaned by the flushing process. Therefore, measures preventing hydrocarbons from penetrating into the gap space 5 between the activated carbon filter 1 and the housing inner wall 6 and preferably additionally allow absorption or adsorption of the hydrocarbons in the gap space 5, are required according to the aspects of the present invention.

LIST OF REFERENCE NUMERALS

[0035] 1 activated carbon filter

[0036] 2 channel

[0037] 3 channel wall

[0038] 4 sealing device

[0039] 5 gap space

[0040] 6 housing inner wall

[0041] 7 filter peripheral wall

[0042] 8 coating

[0043] 9 housing

[0044] 10 activated carbon filter system