Patent Publication Number: US-2020291903-A1

Title: Canister

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Japanese Patent Application No. 2019-048511 filed on Mar. 15, 2019 with the Japan Patent Office, the entire disclosure of which is incorporated herein by reference. 
     BACKGROUND 
     The present disclosure relates to a canister. 
     A vehicle is equipped with a canister for inhibiting an evaporated fuel in a fuel tank from being discharged into the atmosphere. Such a canister draws the evaporated fuel from the fuel tank via a charge port, and absorbs the evaporated fuel using activated carbon. The evaporated fuel absorbed by the activated carbon in the canister is then discharged into an engine by purging. More specifically, the canister draws the atmosphere through an atmosphere port by a negative intake air pressure; allows the evaporated fuel absorbed by the activated carbon to be desorbed; and supplies the engine with the desorbed evaporated fuel through the purge port. 
     The canister comprises a main chamber including the charge port and the purge port, and at least one subsidiary chamber coupled to the main chamber. The at least one subsidiary chamber includes a subsidiary chamber that comprises the atmosphere port. Each of these chambers includes activated carbon for absorbing the evaporated fuel. To adjust a capacity to absorb/desorb the fuel, each chamber is designed to have an appropriately determined ratio (L/D) of a length (L) in flowing directions of a gas to an equivalent diameter (D) of a cross-section taken orthogonally to the flowing directions (see Japanese Unexamined Patent Application Publication No. 2012-007501). 
     SUMMARY 
     A recent low emission vehicle such as a hybrid vehicle draws reduced amount of the atmosphere by purging, which causes insufficient desorption of a fuel by purging. As a result, such a vehicle (hereinafter referred to as low-purge vehicle) has an increased amount of evaporated fuel remained in a canister, and may easily discharge the evaporated fuel into the atmosphere through an atmosphere port. 
     One aspect of the present disclosure desirably reduces discharge of a fuel into the atmosphere in the low-purge vehicle. 
     One aspect of the present disclosure is a canister configured to accumulate an evaporated fuel generated in a fuel tank of a vehicle. The canister comprises a charge port, a purge port, an atmosphere port, a main chamber, and at least one subsidiary chamber. The charge port is configured to draw the evaporated fuel. The purge port is configured to discharge the evaporated fuel. The atmosphere port is open to atmosphere. The charge port and the purge port is located in the main chamber. A main absorption layer containing activated carbon is disposed in the main chamber. The at least one subsidiary chamber extends in longitudinal directions: the longitudinal directions include a first side and a second side. A subsidiary absorption layer containing activated carbon is disposed in the at least one subsidiary chamber. A first side end of the at least one subsidiary chamber is coupled to the main chamber or a second side end of a different subsidiary chamber included in the at least one subsidiary chamber. The at least one subsidiary chamber includes a subsidiary chamber, in a second side end of which the atmosphere port is located. The at least one subsidiary chamber includes at least one specified subsidiary chamber, in which the subsidiary absorption layer configured as a specified absorption layer is located. The ratio (L/D) of a length (L) of the specified absorption layer disposed in the at least one specified subsidiary chamber in the longitudinal directions to an equivalent diameter (D) of a cross-section of the specified absorption layer taken orthogonally to the longitudinal directions is equal to or greater than 2.0 and equal to or less than 7.0. The activated carbon included in the specified absorption layer is specified activated carbon having butane working capacity (BWC) equal to or greater than 8.0 g/dL and equal to or less than 10.5 g/dL, measured in accordance with D5228 of ASTM Standards. 
     According to the aforementioned configuration, the specified absorption layer in the specified subsidiary chamber includes the specified activated carbon, and therefore a capacity to absorb the fuel is improved. In addition, by setting the L/D of the specified absorption layer to equal to or greater than 2.0 and equal to or less than 7.0, a gas that flows down the specified subsidiary chamber efficiently contacts the specified absorption layer, which helps inhibit an increase in pressure loss. Thus, the absorbed fuel can be more efficiently removed in the specified absorption layer by purging, which can reduce remaining fuel. Therefore, discharge of the fuel to the atmosphere can be reduced in a low-purge vehicle. 
     In one aspect of the present disclosure, a honeycomb absorbent including the specified activated carbon may be located in the specified absorption layer. The honeycomb absorbent may be cylindrical and located in the at least one specified subsidiary chamber so as to extend in the longitudinal directions. The honeycomb absorbent may include flow passes passing through the honeycomb absorbent in the longitudinal directions. 
     In one aspect of the present disclosure, the specified absorption layer may include hollow activated carbon; each hollow activated carbon is a granular member containing the specified activated carbon. The hollow activated carbon may include at least one hole passing therethrough. 
     According to the aforementioned configuration, the pressure loss can be further reduced when the gas passes through the specified subsidiary chamber. Thus, the accumulated fuel in the canister can be more efficiently removed by purging and the fuel remaining in the canister can be reduced. Therefore, discharge of the fuel to the atmosphere can be reduced in the low-purge vehicle. 
     In one aspect of the present disclosure, the specified absorption layer may include at least one member containing the specified activated carbon. The at least one member may have an improved capacity to absorb the evaporated fuel and an improved capacity to desorb the evaporated fuel absorbed in the at least one member by disposing elongated vent holes. 
     According to the aforementioned configuration, the specified absorption layer improves the capacity to absorb the fuel as well as the capacity to desorb the absorbed fuel. Therefore, discharge of the fuel to the atmosphere can be reduced in the low-purge vehicle. 
     In one aspect of the present disclosure, a ratio of a volume of the main absorption layer of the main chamber to a volume of the specified absorption layer may be equal to or greater than 5.5 and equal to or less than 10. 
     According to the aforementioned configuration, an amount of fuel remaining in the specified subsidiary chamber after purging can be reduced while inhibiting an increase in the pressure loss. As a result, discharge of the fuel from the atmosphere port can be reduced. 
     In one aspect of the present disclosure, a ratio of a volume of the main absorption layer of the main chamber to a sum of volumes of the subsidiary absorption layers of all of the at least one subsidiary chamber may be equal to or greater than 5.5 and equal to or less than 10. 
     According to the aforementioned configuration, an amount of fuel remaining in the specified subsidiary chamber after purging can be reduced while inhibiting an increase in the pressure loss. As a result, discharge of the fuel from the atmosphere port can be reduced. 
     In one aspect of the present disclosure, the canister may further comprise a casing comprising the main chamber, and a subsidiary casing separated from the casing. The at least one subsidiary chamber includes a plurality of subsidiary chambers. One subsidiary chamber among the subsidiary chambers is located in the subsidiary casing and rest of the subsidiary chambers are located in the casing. A first side end of the subsidiary chamber in the subsidiary casing may be coupled to a second side end of one of the rest of the subsidiary chambers in the casing via a hose. The atmosphere port may be provided at a second side end of the subsidiary chamber in the subsidiary casing. 
     According to the aforementioned configuration, the subsidiary chamber provided with the atmosphere port is separated from the casing where the main chamber and the at least one subsidiary chamber are provided. This enables the canister to be installed in the vehicle in various forms. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       An example embodiment of the present disclosure will be described hereinafter with reference to the accompanying drawings, in which: 
         FIG. 1  is an explanatory diagram showing a transparent view of a canister of a first embodiment where a first subsidiary chamber is configured as a specified subsidiary chamber; 
         FIG. 2  is an explanatory diagram showing a transparent view of the canister of the first embodiment where a second subsidiary chamber is configured as the specified subsidiary chamber. 
         FIG. 3  is an explanatory diagram showing a transparent view of the canister of the first embodiment where the first and the second subsidiary chambers are configured as the specified subsidiary chambers; 
         FIG. 4  is a perspective view of a honeycomb absorbent; 
         FIG. 5  is an explanatory diagram showing vent holes formed on the honeycomb absorbent; 
         FIG. 6  is a perspective view showing hollow activated carbon; 
         FIG. 7  is a perspective view showing granular activated carbon; and 
         FIG. 8  is an explanatory diagram showing a canister of a second embodiment. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     The present disclosure is not limited to the embodiments explained hereinafter and may be modified in various modes within the technical scope of the present disclosure. 
     Embodiment 1 
     [1. Outline] 
     In  FIG. 1  to  FIG. 3 , a canister  1  of a first embodiment is shown. The canister  1  is installed in a vehicle and is configured to accumulate an evaporated fuel generated in a fuel tank of the vehicle. The canister  1  comprises a casing  10 , a main chamber  2 , a first subsidiary chamber  3 , a second subsidiary chamber  4 , a charge port  27 , a purge port  28 , an atmosphere port  45 , a main absorption layer  20 , a first subsidiary absorption layer  30 , and a second subsidiary absorption layer  40 ; each absorption layer includes activated carbon. 
     The casing  10  is made of materials such as a synthetic resin. The casing  10  houses the main chamber  2 , the first subsidiary chamber  3 , and the second subsidiary chamber  4 . Hereinafter, one side of each chamber along longitudinal directions  11  (in other words, flowing directions of a fluid) is a first side  12 ; and the other side is a second side  13 . 
     The charge port  27  is coupled to the fuel tank of the vehicle via a tube. The charge port  27  draws the evaporated fuel generated in the fuel tank into the casing  10 . 
     The purge port  28  is coupled to an inlet pipe of an engine of the vehicle via a purge valve. The purge port  28  discharges the evaporated fuel accumulated inside the casing  10  and supplies the engine with the discharged evaporated fuel. 
     The atmosphere port  45  is coupled to a fuel inlet of the vehicle via a tube, and is open to the atmosphere. The atmosphere port  45  discharges a gas removed of the evaporated fuel to the atmosphere. The atmosphere port  45  draws the atmosphere (in other words, purge air) and thereby desorbs (hereinafter, purges) the evaporated fuel accumulated in the casing  10 . Thus purged evaporated fuel is discharged through the purge port  28 . 
     The main absorption layer  20  is located in the main chamber  2 . The main absorption layer  20  is filled with absorbent materials including the activated carbon. An air permeable resin plate  22  and a filter  21  are stacked adjacent to the main absorption layer  20  on the first side  12 ; a filter  25  is stacked adjacent to the main absorption layer  20  on the second side  13 . A space  23  is provided at a first side end of the main chamber  2  located on the first side  12 . The space  23  communicates the main absorption layer  20  with the first subsidiary chamber  3 . The space  23  includes a spring  24  configured to press the resin plate  22  and the filter  21  towards the second side  13 . The charge port  27  and the purge port  28  are located at a second side end of the main chamber  2  located on the second side  13 . A space  26  is provided between these ports  27 ,  28  and the filter  25 . 
     The first subsidiary chamber  3  and the second subsidiary chamber  4  are located adjacent to the main chamber  2  and arranged side by side along the longitudinal directions  11 . The first subsidiary absorption layer  30  is located in the first subsidiary chamber  3 ; and the second subsidiary absorption layer  40  is located in the second subsidiary chamber  4 . The first subsidiary chamber  3  and the second subsidiary chamber  4  are configured to communicate with the main chamber  2  to let the gas flow. The first subsidiary absorption layer  30  and the second subsidiary absorption layer  40  are filled with absorbent materials including the activated carbon. 
     The first subsidiary absorption layer  30  is located in the first subsidiary chamber  3 . A resin plate  32  and a filter  31 , similar to the aforementioned resin plate  22  and filter  21 , are stacked adjacent to the first subsidiary absorption layer  30  on the first side  12 . A filter  35  is stacked adjacent to the first subsidiary absorption layer  30  on the second side  13 . A space  33  is provided at a first side end of the first subsidiary chamber  3  on the first side  12 . The space  33  communicates the first subsidiary chamber  3  with the main chamber  2 . In other words, the first side end of the first subsidiary chamber  3  is coupled to the first side end of the main chamber  2 . The space  33  includes a spring  34  configured to press the resin plate  32  and the filter  31  towards the second side  13 . 
     The second subsidiary absorption layer  40  is located in the second subsidiary chamber  4 . A filter  41  is stacked adjacent to the second subsidiary absorption layer  40  on the first side  12 ; a filter  42  is stacked adjacent to the second subsidiary absorption layer  40  on the second side  13 . A space  43  is provided at a first side end of the second subsidiary chamber  4  on the first side  12 . The space  43  communicates the second subsidiary chamber  4  with the first subsidiary chamber  3 . In other words, the first side end of the second subsidiary chamber  4  is coupled to the second side end of the first subsidiary chamber  3  on the second side  13 . The atmosphere port  45  is located at a second side end of the second subsidiary chamber  4  on the second side  13 . A space  44  is provided between the atmosphere port  45  and the filter  42 . 
     The evaporated fuel drawn through the charge port  27  enters the main chamber  2  and is absorbed by the main absorption layer  20 . An excess of the evaporated fuel that is not absorbed by the main absorption layer  20  enters the first subsidiary chamber  3  through the space  23 , and absorbed by the first subsidiary absorption layer  30 . A further excess of the evaporated fuel that is not absorbed by the first subsidiary absorption layer  30  enters the second subsidiary chamber  4  and absorbed by the second subsidiary absorption layer  40 . The gas removed of the evaporated fuel is discharged through the atmosphere port  45 . 
     The purge air is drawn through the atmosphere port  45  by a negative intake air pressure in the engine. The purge air sequentially enters the second subsidiary chamber  4 , the first subsidiary chamber  3 , and the main chamber  2  in this order, and removes the fuel absorbed in the absorption layer of each chamber. The removed fuel is discharged with the purge air through the purge port  28  and supplied to the engine. 
     [2. Specified Subsidiary Chamber] 
     At least one of the first subsidiary chamber  3  or the second subsidiary chamber  4  in the canister  1  is configured as a specified subsidiary chamber (see  FIG. 1  to  FIG. 3 ). A ratio (L/D) of a length (L) of the subsidiary absorption layer disposed in the specified subsidiary chamber in the longitudinal directions  11  to an equivalent diameter (D) of a cross-section of the subsidiary absorption layer taken orthogonally to the longitudinal directions  11  is equal to or greater than 2.0 and equal to or less than 7.0. The equivalent diameter is a value of a diameter of a true circle (D=(S/π) 1/2 ×2) which has an area S that is the same as an area of the cross-section taken orthogonally to the longitudinal directions  11 , averaged by the length L in the longitudinal directions  11 . 
     The activated carbon included in the subsidiary absorption layer of the specified subsidiary chamber (hereinafter referred to as specified absorption layer) is specified activated carbon that has butane working capacity (BWC) equal to or greater than 8.0 g/dL and equal to or less than 10.5 g/dL, measured in accordance with D5228 of ASTM Standards. 
     As shown in  FIG. 1 , the first subsidiary chamber  3  may be configured as the specified subsidiary chamber. Nevertheless, the second subsidiary chamber  4  may be configured as the specified subsidiary chamber (see  FIG. 2 ) or all of the subsidiary chambers (the first subsidiary chamber  3  and the second subsidiary chamber  4 ) may be configured as the specified subsidiary chambers (see  FIG. 3 ). 
     A honeycomb absorbent  6  that includes the specified activated carbon may be located in the specified absorption layer (see  FIG. 4 ). The honeycomb absorbent  6  has a cylindrical side wall  60  and is located in the specified subsidiary chamber so as to extend in the longitudinal directions  11 . A diameter of a cross-section of the side wall  60  taken orthogonally to the longitudinal directions  11 , may be from 29 mm to 45 mm for example. The honeycomb absorbent  6  also has wall members arranged in grid patterns inside of the side wall  60 . Spaces between these wall members form flow passes  61  passing through the honeycomb absorbent  6  in the longitudinal directions  11 . Each of the flow passes  61  linearly extends in the longitudinal directions  11 . The honeycomb absorbent  6  is formed by fixing the specified activated carbon with a binder. 
     The honeycomb absorbent  6  includes elongated vent holes  62  formed inside the honeycomb absorbent  6  (see  FIG. 5 ). This improves a capacity to absorb the evaporated fuel and a capacity to desorb the absorbed evaporated fuel. The vent holes  62  include at least main vent holes  620  extending from a surface of the honeycomb absorbent  6 ; first branch holes  621  branching from the main vent holes  620 ; and second branch holes  622  branching further from the first branch holes  621 . There may be further vent holes branching from the second branch holes  622 . These vent holes  62  are created by first forming the honeycomb absorbent  6  using the specified activated carbon and the binder mixed with additives, and then removing the additives by a chemical agent and the like. Details about the vent holes should be found in Japanese Unexamined Patent Application Publication No. 2010-001862. 
     The specified absorption layer may also be filled with granular hollow activated carbon  7  (see  FIG. 6 ) containing the specified activated carbon. Each hollow activated carbon  7  includes holes  73  to  75  passing through the hollow activated carbon  7 . More specifically, the hollow activated carbon  7  includes a cylindrical outer wall  70 . A cross sectional diameter of the outer wall  70  may be, for example, 3 mm to 5 mm. The hollow activated carbon  7  includes two inner walls  71 ,  72  inside the outer wall  70 . The inner walls  71 ,  72  are disposed transversely in an inner space of the outer wall  70  and arranged approximately parallel with each other interposing a center axis of the cylindrical outer wall  70 . Ends of the inner walls  71 ,  72  are connected to an inner circumferential surface of the outer wall  70 . Clearances formed by the outer wall  70  and the inner walls  71 ,  72  provide the holes  73  to  75 . The shape of the hollow activated carbon  7  and the number of holes that pass through the hollow activated carbon  7  should not be limited and may be determined appropriately. 
     The specified absorption layer may also be filled with granular activated carbon  8  (see  FIG. 7 ). Each granular activated carbon  8  is formed into a columnar shape. A cross sectional diameter of the granular activated carbon  8  may be, for example, 3 mm to 5 mm. 
     Likewise with the honeycomb absorbent  6 , the hollow activated carbon  7  and the granular activated carbon  8  are created by fixing the specified activated carbon with the binder. The hollow activated carbon  7  and the granular activated carbon  8  also include the vent holes  62  similar to those included in the honeycomb absorbent  6 . This improves the capacity to absorb the evaporated fuel and the capacity to desorb the absorbed evaporated fuel. 
     The hollow activated carbon  7  and the granular activated carbon  8  fill the specified absorption layer unaligned, without adjustment of orientation. The shapes and the like of the hollow activated carbon  7  and granular activated carbon  8  should not be limited and may be determined appropriately. 
     The honeycomb absorbent  6 , the hollow activated carbon  7 , or the granular activated carbon  8  arranged in the specified absorption layer does not have to include the aforementioned vent holes  62 . 
     [3. Volume Ratio] 
     In the first embodiment, a ratio of a volume of the main absorption layer  20  of the main chamber  2  to a volume of the specified absorption layer is equal to or greater than 5.5 and equal to or less than 10 (see  FIG. 1, 2 ). 
     The volume of the main absorption layer  20  is M, and the volume of the specified absorption layer is X 0 . In other words, the volume ratio is M/X 0 . In addition, a ratio of the volume of the main absorption layer  20  to a sum of volumes (X 1 ) of all the subsidiary absorption layers in all the subsidiary chambers (the first subsidiary absorption layer  30  of the subsidiary chamber  3  and the second subsidiary absorption layer  40  of the subsidiary chamber  4 ) in the canister  1  may be equal to or greater than 5.5 and equal to or less than 10 (see  FIG. 3 ). In other words, the volume ratio is M/X 1 . If there are two or more specified subsidiary chambers, a ratio of a volume of the main absorption layer  20  of the main chamber  2  to a sum of volumes (X 2 ) of all the specified absorption layers of all the specified subsidiary chambers may be equal to or greater than 5.5 and equal to or less than 10. In other words, the volume ratio is M/X 2 . These volume ratios may also have different values. 
     Embodiment 2 
     [4. Outline] 
     The canister  100  in the second embodiment shown in  FIG. 8  has a configuration similar to that of the first embodiment, but is different from the first embodiment in that there are a subsidiary casing  14  and other elements. Hereinafter, the canister  100  will be explained mainly about such differences. The same reference numeral as the first embodiment suggest the same configuration, and the reference of such configuration should be made to the preceding explanations. 
     Similarly to the first embodiment, the canister  100  comprises the casing  10 , the main chamber  2 , the first subsidiary chamber  3 , the second subsidiary chamber  4 , the charge port  27 , the purge port  28 , an atmosphere port  55 , and the absorption layers  20 ,  30 ,  40  each comprising activated carbon. The canister  100  further comprises a subsidiary casing  14 , a separated subsidiary chamber  5 , a hose  15 , and a third subsidiary absorption layer  50 . 
     The subsidiary casing  14  is made of a material such as a synthetic resin and houses the separated subsidiary chamber  5 . The subsidiary casing  14  is separated from the casing  10 . The subsidiary casing  14  includes the atmosphere port  55 . 
     The third subsidiary absorption layer  50 , configured similarly to the subsidiary absorption layers in the first embodiment, is disposed in the separated subsidiary chamber  5 . A filter  51  is stacked adjacent to the third subsidiary absorption layer  50  on the first side  12 . A filter  53  is stacked adjacent to the third subsidiary absorption layer  50  on the second side  13 . A connecting port  56  is provided at a first side end of the separated subsidiary chamber  5  on the first side  12 . A space  52  is provided between the connecting port  56  and the filter  51 . The atmosphere port  55  is provided at a second side end of the separated subsidiary chamber  5  on the second side  13 . A space  54  is provided between the atmosphere port  55  and the filter  53 . 
     The second subsidiary chamber  4  is provided with a connecting port  46  in place of the atmosphere port  45 . The connecting port  46  is coupled to the connecting port  56  of the subsidiary casing  14  via the hose  15  made of an element such as resin. A gas flows between the second subsidiary chamber  4  and the separated subsidiary chamber  5  via the hose  15 . The second side end of the second subsidiary chamber  4  is coupled to the first side end of the separated subsidiary chamber  5 . 
     In the canister  100 , the evaporated fuel drawn from the charge port  27  sequentially enters the main chamber  2 , the first subsidiary chamber  3 , and the second subsidiary chamber  4  in this order. An excess of the evaporated fuel that is not absorbed by the absorption layers in these chambers enters the separated subsidiary chamber  5  through the hose  15  and absorbed by the third subsidiary absorption layer  50 . The gas removed of the evaporated fuel is discharged from the atmosphere port  55  that is disposed in the separated subsidiary chamber  5  (in other words, disposed in the subsidiary casing  14 ). 
     The purge air is drawn from the atmosphere port  55  by the negative intake air pressure in the engine. The purge air sequentially enters the separated subsidiary chamber  5 , the second subsidiary chamber  4 , the first subsidiary chamber  3 , and the main chamber  2  in this order, and removes the fuel absorbed in the absorption layer of each chamber. The removed fuel is discharged with the purge air through the purge port  28  and supplied to the engine. 
     [5. Specified Subsidiary Chamber] 
     At least one of the first subsidiary chamber  3 , the second subsidiary chamber  4 , or the separated subsidiary chamber  5  in the canister  100  is configured as a specified subsidiary chamber. A specified absorption layer of the specified subsidiary chamber is configured similarly to that in the first embodiment. In the canister  100  shown in  FIG. 8 , the separated subsidiary chamber  5  is configured as the specified subsidiary chamber. Nevertheless, the first subsidiary chamber  3  may be configured as the specified subsidiary chamber; the second subsidiary chamber  4  may be configured as the specified subsidiary chamber; or both the first subsidiary chamber  3  and the second subsidiary chamber  4  may be configured as the specified subsidiary chambers. In addition, all of the subsidiary chambers  3 ,  4 ,  5  may be configured as the specified subsidiary chambers. 
     [6. Volume Ratio] 
     In the second embodiment, a ratio of a volume of the main absorption layer  20  of the main chamber  2  to a volume of the specified absorption layer (in other words, the third subsidiary absorption layer  50 ) of the separated subsidiary chamber  5  is also equal to or greater than  5 . 5  and equal to or less than  10  (see  FIG. 8 ). The volume of the main absorption layer  20  is M, and the volume of the specified absorption layer is Y 0 . In other words, the volume ratio is M/Y 0 . Nevertheless, if the first subsidiary chamber  3  or the second subsidiary chamber  4  is the specified subsidiary chamber, then a ratio of the volume of the main absorption layer  20  of the main chamber  2  to a sum of volumes (Y 1 ) of all the specified absorption layers of these chambers may be equal to or greater than 5.5 and equal to or less than 10. In other words, the volume ratio is M/Y 1 . Also, a ratio of the volume of the main absorption layer  20  to a sum of volumes (Y 2 ) of all the subsidiary absorption layers  30 ,  40 ,  50  of the subsidiary chambers  3 ,  4 ,  5  may be equal to or greater than 5.5 and equal to or less than 10. In other words, the volume ratio is M/Y 2 . These volume ratios may also have different values. 
     [7. Effect] 
     (1) According to the aforementioned embodiments, the specified absorption layer of the specified subsidiary chamber includes the specified activated carbon, and therefore improves the capacity to absorb the fuel. Moreover, by setting the L/D of the specified absorption layer to equal to or greater than 2.0 and equal to or less than 7.0, the gas that flows down the specified subsidiary chamber efficiently contacts the specified absorption layer, which helps inhibit an increase in pressure loss. Thus, the absorbed fuel can be more efficiently removed by purging in the specified absorption layer, which can reduce remaining fuel. Therefore, discharge of the fuel to the atmosphere can be reduced in a low-purge vehicle. 
     (2) The specified absorption layer includes the honeycomb absorbent  6  or the hollow activated carbon  7 . This helps further reduce the pressure loss when the gas passes through the specified subsidiary chamber. Thus, the accumulated fuel in the canister can be more efficiently removed by purging and the fuel remaining in the canister can be reduced. Therefore, discharge of the fuel to the atmosphere can be reduced in the low-purge vehicle. 
     (3) Due to having the vent holes  62 , the honeycomb absorbent  6 , the hollow activated carbon  7 , and the granular activated carbon  8 , the specified absorption layer improves the capacity to absorb the evaporated fuel and the capacity to desorb the absorbed evaporated fuel. Therefore, discharge of the fuel to the atmosphere can be reduced in the low-purge vehicle. 
     (4) When the ratio of the volume of the main absorption layer  20  to the volume of the specified absorption layer is equal to or greater than 5.5 and equal to or less than 10, an amount of fuel remains in the specified subsidiary chamber after purging can be reduced while inhibiting an increase in the pressure loss. Also, when the ratio of the volume of the main absorption layer  20  to the sum of the volumes of all the subsidiary absorption layers is equal to or greater than 5.5 and equal to or less than 10, an amount of fuel remains in each subsidiary chamber after purging can be reduced while inhibiting an increase in the pressure loss. As a result, discharge of the fuel through the atmosphere port can be reduced. 
     (5) In the canister  100  of the second embodiment, the separated subsidiary chamber  5  provided with the atmosphere port  55  is separated from the casing  10 . This enables the canister  100  to be installed in the vehicle in various forms. 
     [8. Other Embodiment] 
     (1) In the first embodiment, the canister  1  may include one subsidiary chamber or three or more subsidiary chambers. In the second embodiment, the casing  10  may include one subsidiary chamber or three or more subsidiary chambers. 
     (2) Two or more functions of one element in the aforementioned embodiments may be achieved by two or more elements; and one function of one element in the aforementioned embodiments may be achieved by two or more elements. Two or more functions of two or more elements in the aforementioned embodiments may be achieved by one element; one function of two or more elements in the aforementioned embodiments may be achieved by one element. A part of the configuration of the aforementioned embodiments may be omitted. At least a part of the configuration of the aforementioned embodiments may be added to or replaced with another configuration of the aforementioned embodiments.