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A fuel vapor canister is presented, comprising two or more pneumatically coupled concentric adsorbent beds, a vent port configured to deliver fresh air to an outermost concentric adsorbent bed, and a purge port configured to couple an engine intake to an innermost concentric adsorbent bed. The conce

A fuel vapor canister is presented, comprising two or more pneumatically coupled concentric adsorbent beds, a vent port configured to deliver fresh air to an outermost concentric adsorbent bed, and a purge port configured to couple an engine intake to an innermost concentric adsorbent bed. The concentric adsorbent beds facilitate improved purging of the canister, thus decreasing bleed emissions. The concentric adsorbent beds may have a bi-conical structure yielding a conical flow path which allows fresh air to flow through the adsorbent beds equally, reducing the size of a canister heel.

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1. A fuel vapor canister, comprising: two or more pneumatically coupled concentric adsorbent beds;a vent port configured to deliver fresh air to an outermost concentric adsorbent bed; anda purge port configured to couple an engine intake to an innermost concentric adsorbent bed;wherein the concentri

1. A fuel vapor canister, comprising: two or more pneumatically coupled concentric adsorbent beds;a vent port configured to deliver fresh air to an outermost concentric adsorbent bed; anda purge port configured to couple an engine intake to an innermost concentric adsorbent bed;wherein the concentric adsorbent beds have a bi-conical structure comprising two conical shapes adjoined at their respective bases. 2. The fuel vapor canister of claim 1, further comprising: a load port configured to couple a fuel tank to the innermost concentric adsorbent bed. 3. The fuel vapor canister of claim 1, wherein the vent port is located at an apex of an atmospheric-side cone. 4. The fuel vapor canister of claim 1, wherein the purge port is located at an apex of an intake-side cone, and wherein granules of adsorbent material are packed within the beds that have the bi-conical structure. 5. The fuel vapor canister of claim 4, wherein adjacent adsorbent beds are pneumatically coupled via one or more conduits, and wherein the beds are nested inside one another. 6. The fuel vapor canister of claim 5, wherein a flow direction is reversed between adjacent adsorbent beds, and further comprising three or more nested beds. 7. The fuel vapor canister of claim 6, wherein each bed pneumatically communicates with adjacent beds via conduits, and wherein the conduits are located on alternating apexes. 8. A fuel system, comprising: an engine intake; anda fuel vapor canister, comprising: two or more pneumatically coupled concentric adsorbent beds;a vent port configured to deliver fresh air to an outermost concentric adsorbent bed; anda purge port configured to couple the engine intake to an innermost concentric adsorbent bed,wherein the concentric adsorbent beds have a bi-conical structure comprising two conical shapes adjoined at their respective bases. 9. The fuel system of claim 8, further comprising: a fuel tank; anda load port configured to couple the fuel tank to the innermost concentric adsorbent bed. 10. The fuel system of claim 8, wherein a flow direction is reversed between adjacent adsorbent beds, and further comprising at least three concentric adsorbent beds. 11. The fuel system of claim 9, further comprising: a vent line coupling the vent port to atmosphere via a vent valve; andwherein the vent port is located at an apex of an atmospheric-side cone. 12. The fuel system of claim 11, further comprising: a purge line coupling the purge port to the engine intake via a purge valve; andwherein the purge port is located at an apex of an intake-side cone, wherein the intake-side cone is located opposite the atmospheric-side cone. 13. The fuel system of claim 9, further comprising: a conduit coupling the fuel tank to the load port via a fuel tank isolation valve, and at least one conduit connecting adjacent concentric adsorbent beds, the at least one conduit being located at one or more apexes of the adsorbent beds. 14. A method for a fuel system, comprising: during a first condition, directing fresh air to an outermost concentric adsorbent bed of a fuel vapor canister comprising two or more concentric adsorbent beds; anddirecting desorbed hydrocarbons from an innermost concentric adsorbent bed to an engine intake;wherein the concentric adsorbent beds have a bi-conical structure comprising two conical shapes adjoined at their respective bases. 15. The method of claim 14, wherein the first condition includes a fuel vapor canister load above a threshold, wherein the fuel vapor canister includes at least three concentric adsorbent beds, where each bed communicates with an adjacent bed through only one conduit each, and where a direction of gas flow is reversed between adjacent beds. 16. The method of claim 14, wherein directing fresh air to the outermost concentric adsorbent bed comprises opening a vent valve coupled between the outermost concentric adsorbent bed and atmosphere, and wherein directing desorbed hydrocarbons from the innermost concentric adsorbent bed to the engine intake comprises opening a purge valve coupled between the innermost concentric adsorbent bed and the engine intake, and wherein the concentric adsorbent beds comprise granules of adsorbent material packed within the beds having the bi-conical structure, where the beds having the bi-conical structure are nested inside one another. 17. The method of claim 14, further comprising: during a second condition, directing fuel vapor from a fuel tank to the innermost concentric adsorbent bed; anddirecting gasses stripped of fuel vapor from the outermost concentric adsorbent bed to atmosphere;wherein the fresh air is directed to an apex on an atmospheric side of the fuel vapor canister. 18. The method of claim 17, where the second condition includes a refueling event, and wherein the desorbed hydrocarbons are directed from an apex on an intake side of the fuel vapor canister, the intake side opposite the atmospheric side. 19. The method of claim 17, wherein directing fuel vapor from the fuel tank to the innermost concentric adsorbent bed comprises opening a fuel tank isolation valve coupled between the fuel tank and the innermost concentric adsorbent bed, and wherein directing gasses stripped of fuel vapor from the outermost concentric adsorbent bed to atmosphere comprises opening a vent valve coupled between the outermost concentric adsorbent bed and atmosphere.