Canister

Abstract

To suppress discharge of vaporized fuel from an atmospheric port.SOLUTION: A canister includes a charge port, a purge port, an atmospheric port, a main chamber, a sub chamber, and an active carbon. In the main chamber, the charge port and the purge port are connected. The sub chamber communicates with the main chamber, and the atmospheric port is connected directly or via other chamber. The active carbon is stored in each of the main chamber and the sub chamber. In the sub chamber, the ratio L / D of the length L[mm] in an air flow direction with respect to a corresponding diameter D[mm] in a cross-sectional face vertical to the air flow direction is 2 or more. A ratio of the volume of the active carbon of the main chamber with respect to the volume the active carbon of the sub chamber is more than 5.5 to 10 or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a canister.

Background Art

[0002] Vehicles are equipped with a canister to prevent the release of evaporated fuel generated in the fuel tank. The canister has a main chamber and an auxiliary chamber, and is configured to adsorb the evaporated fuel to the activated carbon stored in these chambers. Further, purge is performed in which air (hereinafter, purge air) is sucked from the atmosphere port using the intake negative pressure of the engine, and fuel is desorbed from the activated carbon in these chambers, and the desorbed evaporated fuel is supplied to the engine. Further, in order to adjust the adsorption efficiency of the activated carbon to the evaporated fuel, in each chamber, the ratio (L / D) of the length L in the gas flow direction to the equivalent diameter D in the cross section perpendicular to the gas flow direction is designed (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, due to hybridization and downsizing of vehicles, etc., the exhaust volume of the engine has decreased, and accordingly, the amount of purge air sucked by the intake negative pressure during purge has decreased. As a result, the desorption of the evaporated fuel by purge becomes insufficient, and there is a risk that the evaporated fuel is likely to be released from the atmosphere port.

[0005] In one aspect of the present disclosure, it is desirable to suppress the release of the evaporated fuel from the atmosphere port.

Means for Solving the Problems

[0006] One aspect of the present disclosure is a canister that adsorbs and desorbs evaporated fuel generated in a fuel tank of a vehicle, and includes a charge port, a purge port, an atmosphere port, a main chamber, a sub-chamber, and activated carbon. The charge port takes in the evaporated fuel. The purge port discharges the evaporated fuel. The atmosphere port is open to the atmosphere. The main chamber is connected to the charge port and the purge port. The sub-chamber communicates with the main chamber, and the atmosphere port is directly or connected via another chamber. The activated carbon is housed in the main chamber and the sub-chamber, respectively. In the sub-chamber, the ratio L / D of the length L [mm] in the gas flow direction to the equivalent diameter D [mm] in a cross section perpendicular to the gas flow direction is 2 or more. The ratio of the volume of the activated carbon housed in the main chamber to the volume of the activated carbon housed in the sub-chamber is more than 5.5 and 10 or less. The emission amount when the unit adsorption amount measured by the DBL test becomes 17.6 g / L is 100 mg or less, and the unit adsorption amount is a value obtained by dividing the weight [g] of the evaporated fuel adsorbed in the canister by the volume [L] of the activated carbon housed in the main chamber and the sub-chamber.

[0007] According to the above configuration, while suppressing the pressure loss, it is possible to reduce the remaining amount of the evaporated fuel after purging in the sub-chamber, and to maintain the adsorption and desorption efficiency in the sub-chamber while reducing the volume of the sub-chamber. And thereby, the emission amount measured by the DBL test can be suppressed, and as a result, the release of the evaporated fuel from the atmosphere port can be suppressed.

[0008] In one aspect of the present disclosure, the adsorption capacity of the evaporated fuel of the activated carbon housed in the main chamber may be greater than or equivalent to the adsorption capacity of the evaporated fuel of the activated carbon housed in the sub-chamber. According to the above configuration, the release of the evaporated fuel from the atmosphere port can be further suppressed.

[0009] One aspect of the present disclosure may further include at least one rib protruding from a wall portion facing the activated carbon in the main chamber. The rib may extend along the gas flow direction. As the ratio of the volume of the activated carbon in the main chamber to the volume of the activated carbon in the sub-chamber is within the above range, the main chamber increases in size and the rigidity of the main chamber decreases. As a result, as evaporated fuel accumulates in the main chamber, the main chamber may bulge. On the other hand, according to the above configuration, since the rigidity of the main chamber is improved by at least one rib, it is possible to suppress the main chamber from bulging.

[0010] In one aspect of the present disclosure, the main chamber and the sub-chamber may be arranged side by side along a first direction substantially orthogonal to the gas flow direction. The wall portion has two first wall portions facing each other along a second direction substantially orthogonal to the first direction and the gas flow direction, and two second wall portions facing each other along the first direction, and each of the first wall portions may be wider than each of the two second wall portions. The rib may be provided on the first wall portion.

[0011] According to the above configuration, it is possible to more effectively suppress the main chamber from bulging. In one aspect of the present disclosure, a plurality of ribs may be provided on at least two of the two first wall portions and the two second wall portions.

[0012] According to the above configuration, since the rigidity of the main chamber is further improved, it is possible to more effectively suppress the main chamber from bulging.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0014] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings. [1. First Embodiment] [(1) Overall Configuration] As shown in FIGS. 1A and 1B, the canister 1 of the first embodiment adsorbs and desorbs the evaporated fuel generated in the fuel tank of the vehicle. The canister 1 includes a charge port 2A, a purge port 2B, an atmosphere port 2C, a main chamber 3, a sub-chamber 4, main chamber activated carbon 5A, and sub-chamber activated carbon 5B. As an example, the main chamber activated carbon 5A and the sub-chamber activated carbon 5B are granular, but are not limited thereto, and for example, powdered activated carbon may be used.

[0015] [(2) Ports] The charge port 2A is connected to the fuel tank of the vehicle by a pipe (see FIGS. 1A and 1B). The charge port 2A is configured to take in the evaporated fuel generated in the fuel tank into the canister 1.

[0016] The purge port 2B is connected to the intake pipe of the vehicle engine via a purge valve. The purge port 2B is configured to discharge the evaporated fuel detached from the main chamber activated carbon 5A and the sub-chamber activated carbon 5B stored in the canister 1 toward the engine during purging.

[0017] The atmosphere port 2C is connected to the fuel filler neck of the vehicle via a pipe and is open to the atmosphere. The atmosphere port 2C discharges the gas from which the evaporated fuel has been removed into the atmosphere. Further, the atmosphere port 2C takes in air (in other words, purge air) from the outside of the vehicle by the intake negative pressure of the engine during purging. Thereby, the evaporated fuel detaches from the main chamber activated carbon 5A and the sub-chamber activated carbon 5B stored in the canister 1.

[0018] [(3) Main chamber] The main chamber 3 is a portion extending in the gas flow direction 1A and houses the main chamber activated carbon 5A therein (see FIGS. 1A and 1B). The interior of the main chamber 3 is partitioned by two filters 3D into a first space 3A, a second space 3B, and a third space 3C arranged in the gas flow direction 1A. The filter 3D is configured to allow gas to pass through while not allowing activated carbon to pass through.

[0019] The first space 3A is sandwiched between the second space 3B and the third space 3C and is filled with the main chamber activated carbon 5A. The first space 3A has a larger volume than the second space 3B and the third space 3C. The second space 3B is adjacent to the first space 3A, and the charge port 2A and the purge port 2B are connected thereto. Note that no activated carbon is disposed in the second space 3B. Further, in the second space 3B, a plurality of rod-shaped portions 3G extending in the gas flow direction 1A from the end of the housing constituting the main chamber 3 and contacting the filter 3D are disposed.

[0020] The third space 3C is adjacent to the first space 3A and communicates with the second space 4B of the auxiliary chamber 4 described later. Note that activated carbon is not arranged in the third space 3C. Further, in the third space 3C, a resin plate 3E having through holes is provided adjacent to the filter 3D, and a spring 3F that presses the resin plate 3E and the filter 3D toward the first space 3A is arranged.

[0021] Note that the main chamber activated carbon 5A in the main chamber 3 has a higher adsorption capacity for evaporated fuel, in other words, a higher butane working capacity (BWC) than the auxiliary chamber activated carbon 5B in the auxiliary chamber 4 described later. Of course, this is not the only case, and the main chamber activated carbon 5A and the auxiliary chamber activated carbon 5B may have the same adsorption capacity for evaporated fuel. In addition to this, for example, the main chamber activated carbon 5A may have a lower adsorption capacity for evaporated fuel than the auxiliary chamber activated carbon 5B.

[0022] [(4) Auxiliary Chamber] The auxiliary chamber 4 is arranged alongside the main chamber 3 along a first direction 1B that is substantially orthogonal to the gas flow direction 1A (see FIGS. 1A and 1B). The auxiliary chamber 4 is an elongated portion extending in the gas flow direction 1A, houses the auxiliary chamber activated carbon 5B therein, and communicates with the main chamber 3 so that gas can flow freely between them. The auxiliary chamber 4 has a first space 4A and a second space 4B that are arranged in the gas flow direction 1A.

[0023] The first space 4A is filled with the auxiliary chamber activated carbon 5B, and two filters 4C having the same configuration as the filter 3D in the main chamber 3 are arranged at both ends of the first space 4A in the gas flow direction 1A. Further, an end portion of the first space 4A in the gas flow direction 1A is directly connected to the atmosphere port 2C. Between the first space 4A and the atmosphere port 2C, a filter 4C and a plurality of rod-shaped portions 4F extending from the housing constituting the auxiliary chamber 4 and abutting on the filter 4C are arranged. Note that a resin plate may be arranged between the first space 4A and the atmosphere port 2C.

[0024] The second space 4B is adjacent to the end of the atmosphere port 2C in the first space 4A on the opposite side, and the third space 3C of the main chamber 3 is connected thereto. Note that activated carbon is not disposed in the second space 4B. Further, in the second space 4B, there are disposed a resin plate 4D having through holes and disposed adjacent to the filter 4C, and a spring 4E that presses the resin plate 4D and the filter 4C toward the first space 4A.

[0025] Note that the auxiliary chamber 4 is not connected to the main chamber 3 except for the second space 4B. That is, the flow path connecting the main chamber 3 and the auxiliary chamber 4 is only the flow path including the third space 3C and the second space 4B.

[0026] [(5) Activated Carbon Volume Ratio and L / D] The ratio of the volume of the main chamber activated carbon 5A stored in the first space 3A of the main chamber 3 to the volume of the auxiliary chamber activated carbon 5B stored in the first space 4A of the auxiliary chamber 4 (hereinafter also referred to as "activated carbon volume ratio") is more than 5.5 and 10 or less. Note that as the activated carbon volume ratio, 10 is preferable.

[0027] Further, in the first space 4A filled with the auxiliary chamber activated carbon 5B in the auxiliary chamber 4, the ratio L / D of the length L [mm] in the gas flow direction 1A to the equivalent diameter D [mm] in the cross section perpendicular to the gas flow direction 1A (see FIG. 1B) is 2 or more.

[0028] Note that the equivalent diameter D means a value obtained by averaging, with the length in the gas flow direction 1A of the first space 4A, the diameter of a perfect circle having the same area as the area S of the cross section perpendicular to the gas flow direction 1A in the first space 4A of the auxiliary chamber 4 (D = ((S / π)^(1 / 2)) × 2).

[0029] When L / D is less than 2, the cross-sectional area of the auxiliary chamber activated carbon 5B becomes large, making it difficult for the gas to flow radially outside the atmosphere port 2C, so that a region where the gas does not come into contact may occur. That is, the adsorption efficiency of the canister 1 is significantly reduced. As L / D, 2.5 or more is more preferable, and 3.0 or more is more preferable.

[0030] [(6) Adsorption / Desorption of Evaporated Fuel] The evaporated fuel taken in from the charge port 2A passes through the second space 3B of the main chamber 3 and is adsorbed by the main chamber activated carbon 5A in the first space 3A (see FIGS. 1A and 1B). The evaporated fuel that could not be completely adsorbed in the first space 3A passes through the third space 3C and moves to the sub-chamber 4, where it is adsorbed by the sub-chamber activated carbon 5B in the first space 4A of the sub-chamber 4. The gas from which the evaporated fuel has been removed is discharged from the atmosphere port 2C.

[0031] Also, during purging, by supplying air from the atmosphere port 2C, the evaporated fuel adsorbed by the sub-chamber activated carbon 5B in the first space 4A of the sub-chamber 4 and the evaporated fuel adsorbed by the main chamber activated carbon 5A in the first space 3A of the main chamber 3 are discharged to the engine from the purge port 2B.

[0032] [(7) Ribs of the main chamber] On the wall portion of the housing constituting the main chamber 3 facing the first space 3A, a plurality of vertical ribs 3J protruding toward the first space 3A are provided so as to extend along the gas flow direction 1A (see FIGS. 2A and 2B).

[0033] That is, the wall portion of the main chamber 3 has two first wall portions 3H and two second wall portions 3I. The two first wall portions 3H face each other along the second direction 1C that is substantially orthogonal to the gas flow direction 1A and the first direction 1B (see FIG. 1B). Also, the two second wall portions 3I face each other along the first direction 1B. Note that the two first wall portions 3H have the same width, and the two second wall portions 3I also have the same width. Also, the first wall portion 3H is wider than the second wall portion 3I.

[0034] In the first embodiment, as an example, a plurality of vertical ribs 3J are provided on each of the two first wall portions 3H. In each first wall portion 3H, as an example, the plurality of vertical ribs 3J are arranged over the entire area of the first wall portion 3H at substantially regular intervals. Each vertical rib 3J extends from the first end or the vicinity thereof in the gas flow direction 1A in the first space 3A to the second end or the vicinity thereof.

[0035] Further, the shape of the cross section orthogonal to the gas flow direction 1A in each vertical rib 3J is determined as appropriate. Specifically, for example, the cross section may be a quadrilateral (more specifically, a square or a trapezoid (see FIGS. 2C and 2D)), a triangle (see FIG. 3A), or a semi-circular shape (see FIG. 3B).

[0036] Further, at least one vertical rib 3J may be provided only on one of the two first wall portions 3H, or at least one vertical rib 3J may be provided on each first wall portion 3H. Further, in addition to or instead of one or two first wall portions 3H, at least one vertical rib 3J may be provided on one or two second wall portions 3I (see FIG. 3C).

[0037] Further, in addition to the vertical rib 3J, at least one horizontal rib 3K may be provided that extends substantially orthogonal to the gas flow direction 1A and protrudes from the wall portion into the first space 3A. Note that the horizontal rib 3K may have the same cross section as the vertical rib 3J. As an example, a plurality of horizontal ribs 3K may be provided on each first wall portion 3H, or on one of the first wall portions 3H (see FIG. 3D), or one horizontal rib 3K may be provided. Further, one (or a plurality of) horizontal ribs 3K may be provided so as to circulate the first space 3A across the two first wall portions 3H and the two second wall portions 3I (see FIGS. 4A and 4B).

[0038] Of course, the arrangement patterns of the vertical rib 3J and the horizontal rib 3K are not limited to this and can be determined as appropriate. Further, the vertical rib 3J and the horizontal rib 3K may not be provided on the wall portion of the main chamber 3. [2. Embodiment] By the DBL test, the emission amount when the unit adsorption amount in the canister 1 of the first embodiment was 17.6 g / L was measured. Note that the unit adsorption amount is a value obtained by dividing the total weight [g] of the evaporated fuel adsorbed by the main chamber activated carbon 5A and the sub-chamber activated carbon 5B in the main chamber 3 and the sub-chamber 4 of the canister 1 by the total volume [L] of the main chamber activated carbon 5A and the sub-chamber activated carbon 5B. Hereinafter, the DBL test and the gasoline break-in performed prior to the DBL test will be described.

[0039] [(1) Gasoline conditioning] In gasoline conditioning, the first to third procedures are sequentially carried out. In the first procedure, 2 L of EM90 gasoline 62 manufactured by ENEOS Corporation is stored in a container 61 (see Fig. 5A). The container 61 is, as an example, a flask-shaped member, and its opening is closed by a lid member. Then, the container 61 is placed in the water in a water bath 60, and the EM90 gasoline 62 is heated by heating the water to raise its temperature to 50 °C.

[0040] In the second procedure, two first and second tubes 63, 64 are provided so as to penetrate through the lid member that closes the opening of the container 61. The end of the first tube 63 is located in the EM90 gasoline 62 inside the container 61. The end of the second tube 64 is connected to the charge port 2A of the canister 1 of the first embodiment where the purge port 2B is closed.

[0041] Then, in an environment with an ambient temperature of 25 ± 2 °C, air is sent at a pace of 1.0 L / min through the first tube 63 to the EM90 gasoline 62 in the container 61 to perform bubbling and generate gasoline vapor. Due to bubbling, the gasoline vapor flows into the canister 1 through the second tube 64 and the charge port 2A, and is adsorbed by the main chamber activated carbon 5A and the sub-chamber activated carbon 5B stored in the canister 1. The adsorption of gasoline vapor by bubbling is carried out until the total amount of gasoline vapor released from the atmosphere port 2C due to breakthrough in the main chamber activated carbon 5A and the sub-chamber activated carbon 5B of the canister 1 reaches 2 g.

[0042] In the third procedure, in an environment with an ambient temperature of 25 ± 2 °C, purge is performed by flowing purge air into the inside of the canister 1 from the atmosphere port 2C at a pace of 22.7 L / min. The purge is carried out until the total volume of the inflowing purge air reaches 300 BV. Here, BV is a unit of the value obtained by dividing the volume of the purge air by the total volume of the main chamber activated carbon 5A and the sub-chamber activated carbon 5B stored in the canister 1.

[0043] Then, during gasoline break-in, the cycle having the first to third procedures is repeated six times. At the end of each cycle, the EM90 gasoline 62 used in the first procedure is replaced. That is, in the first procedure of each cycle, new EM90 gasoline 62 is used.

[0044] [(2) DBL test] For the canister 1 on which gasoline break-in has been performed, the DBL test defined by CARB (California Air Resources Board) is performed. In the DBL test, the first to sixth procedures are sequentially implemented.

[0045] In the first procedure, in an environment with an ambient temperature of 25°C, a mixed gas containing n-butane and nitrogen with a volume ratio of n-butane to nitrogen of 50 vol%:50 vol% is allowed to flow into the canister 1 from the charge port 2A at a pace of 40 g / min. Thereby, n-butane is adsorbed onto the main chamber activated carbon 5A and the sub-chamber activated carbon 5B in the canister 1. Then, the inflow of the mixed gas is carried out until the total amount of n-butane released from the atmosphere port 2C due to breakthrough in the main chamber activated carbon 5A and the sub-chamber activated carbon 5B reaches 2 g.

[0046] In the second procedure, the canister 1 is soaked (in other words, left) in an environment with an ambient temperature of 25 ± 5°C for 6 hours. In the third procedure, purging is performed by allowing purge air to flow into the atmosphere port 2C at a pace of 22.7 L / min in an environment with an ambient temperature of 25°C. The purging is carried out until the total volume of the inflowing purge air reaches 110 BV.

[0047] In the fourth procedure, the canister 1 is soaked in an environment with an ambient temperature of 18.3°C for a time period of 18 hours or more and less than 24 hours. In the fifth procedure, the fuel tank is refueled with LEV-III gasoline and the temperature of the LEV-III gasoline is set to 18.3°C. Note that LEV-III gasoline means the gasoline (test fuel) described in the third paragraph of the part below "F. Fuel Specifications" of III-56 in "CALIFORNIA EVAPORATIVE EMISSION STANDARDS AND TEST PROCEDURES FOR 2001 AND SUBSEQUENT MODEL MOTOR VEHICLES", which is a regulation of the United States of America. According to this paragraph, the composition of this gasoline is specified in "part II., section A.100.3.1.2." of "California 2015 and Subsequent Model Criteria Pollutant Exhaust Emission Standards and Test Procedures and 2017 and Subsequent Model Greenhouse Gas Exhaust Emission Standards and Test Procedures for Passenger Cars, Light-Duty Trucks and Medium-Duty Vehicles".

[0048] In the sixth procedure, the fuel tank and the charge port 2A of the canister 1 that has undergone the first to fifth procedures are connected via a tube. Then, the fuel tank and the canister 1 are placed in an environment defined by the VT-SHED method, and the ambient temperature is changed in the range of 18.3°C to 40.6°C according to the DBL temperature cycle defined by the VT-SHED method over a period of two days or more. Note that the VT-SHED method is also simply called the SHED method and is known as an evaluation method for meeting exhaust gas regulations in, for example, the United States of America. The VT-SHED method is also mentioned in, for example, German Patent Application Publication No. 10 2011 003 811, Japanese Unexamined Patent Application Publication No. 2002-235610, Japanese Unexamined Patent Application Publication No. 10-339230, Japanese Unexamined Patent Application Publication No. 07-317610, etc.

[0049] During this period, the unit adsorption amount of the canister 1 is monitored based on the weight of the canister 1, and the total amount of gasoline vapor (in other words, the emission amount) released from the atmosphere port 2C after the start of the temperature change according to the DBL temperature cycle is monitored. Then, the emission amount (mg) when the unit adsorption amount reaches 17.6 g / L is measured, and this emission amount is used as the measurement result of the DBL test.

[0050] [(3) Activated carbon volume ratio and emission amount] While changing the activated carbon volume ratio described above in the range of approximately 4 to 10.5, the gasoline break-in and the DBL test are carried out on the canister 1 of the first embodiment, and the emission amount when the unit adsorption amount reaches 17.6 g / L is measured. The measurement results are shown in FIG. 5B.

[0051] FIG. 5B shows how the emission amount changes when the unit adsorption amount reaches 17.6 g / L as the activated carbon volume ratio changes. From FIG. 5B, it was confirmed that as the activated carbon volume ratio increases, the above-mentioned emission amount decreases, and when the activated carbon volume ratio reaches 5.5, the above-mentioned emission amount falls below 100 mg. Also, even after the activated carbon volume ratio exceeds 5.5, the above-mentioned emission amount decreases as the activated carbon volume ratio increases, and when the activated carbon volume ratio exceeds 10, the above-mentioned emission amount becomes substantially constant.

[0052] As described above, the activated carbon volume ratio of the canister 1 of the first embodiment is more than 5.5 and 10 or less. Therefore, for the canister 1, the emission amount when the unit adsorption amount reaches 17.6 g / L, which is measured by the above-mentioned DBL test, is 100 mg or less.

[0053] [3. Second Embodiment] [(1) Outline] The canister 1 of the second embodiment is different from that of the first embodiment in that, in addition to the main chamber 3 and the sub-chamber 4 similar to those of the first embodiment, it includes a third chamber 7 (see FIGS. 6A and 6B). In the canister 1 of the second embodiment as well, the activated carbon volume ratio between the main chamber 3 and the sub-chamber 4 exceeds 5.5 and is 10 or less, and the emission amount when the unit adsorption amount measured by the DBL test is 17.6 g / L is 100 mg or less. Hereinafter, the differences between the canister 1 in the second embodiment and that in the first embodiment will be described.

[0054] [(2) Third chamber] In the second embodiment, at the end of the gas flow direction 1A in the sub-chamber 4, instead of the atmosphere port, the third chamber 7 is connected. The third chamber 7 is an elongated part extending along the gas flow direction 1A, and the third chamber activated carbon 5C is housed inside. Note that the volume of the third chamber activated carbon 5C is smaller than the volume of the sub-chamber activated carbon 5B housed in the sub-chamber 4.

[0055] The first end of the gas flow direction 1A in the third chamber 7 is connected to the end of the sub-chamber 4. Also, an atmosphere port 2C is connected to the second end of the gas flow direction 1A in the third chamber 7. That is, the third chamber 7 is disposed between the sub-chamber 4 and the atmosphere port 2C in the canister 1 of the first embodiment. The atmosphere port 2C is connected to the sub-chamber 4 via the third chamber 7.

[0056] The third chamber activated carbon 5C may be, for example, a honeycomb-shaped activated carbon formed in a cylindrical shape and having a plurality of through holes extending in the gas flow direction (FIG. 6A). The third chamber activated carbon 5C may be manufactured, for example, by kneading powdered activated carbon and a binder and molding it into a honeycomb shape. Also, the third chamber activated carbon 5C is disposed inside the third chamber 7 while being held via a holding member (not shown). Also, the shape of the plurality of through holes in the third chamber activated carbon 5C is not particularly limited and can have various shapes.

[0057] In addition to this, the third chamber activated carbon 5C may have a plurality of activated carbon layers with different adsorption capabilities for the evaporated fuel. Note that the activated carbon of each layer may be, for example, in powder form or in granular form.

[0058] As an example, the third chamber activated carbon 5C may have two activated carbon layers, a first layer 5D located on the side of the auxiliary chamber 4 and a second layer 5E located on the side of the atmosphere port 2C (see FIG. 6B). As an example, the activated carbon of the first layer 5D has a higher adsorption capacity than the activated carbon of the second layer 5E. By doing so, the outflow of the evaporated fuel to the atmosphere port 2C can be more reliably suppressed.

[0059] Of course, this is not limited thereto, and the activated carbon of the first layer 5D may have a lower adsorption capacity than the activated carbon of the second layer 5E. [4. Effects] (1) According to the canister 1 of the first and second embodiments, the activated carbon volume ratio between the main chamber 3 and the auxiliary chamber 4 is more than 5.5 and 10 or less. Further, in the canister 1, the emission amount when the unit adsorption amount measured by the DBL test is 17.6 g / L is 100 mg or less. Therefore, while suppressing the pressure loss, it is possible to reduce the remaining amount of the evaporated fuel after purging in the auxiliary chamber 4, and to maintain the adsorption and desorption efficiency in the auxiliary chamber 4 while reducing the volume of the auxiliary chamber 4. And thereby, the emission amount measured by the DBL test can be suppressed, and as a result, the release of the evaporated fuel from the atmosphere port 2C can be suppressed.

[0060] Also, by setting the activated carbon volume ratio to be greater than 5.5 and 10 or less, while suppressing the increase in the pressure loss due to the reduction of the flow path cross-sectional area of the auxiliary chamber 4, it is possible to reduce the remaining amount of the evaporated fuel in the auxiliary chamber 4 at an early stage with a smaller purge amount. As a result, the release of the evaporated fuel from the atmosphere port 2C can be suppressed. Further, by setting the L / D of the auxiliary chamber 4 to 2 or more, since the gas comes into contact with the adsorbate in the auxiliary chamber 4 more, it is possible to maintain the adsorption and desorption efficiency in the auxiliary chamber 4 while reducing the volume of the auxiliary chamber 4.

[0061] (2) Also, the adsorption capacity of the evaporation fuel in the main chamber activated carbon 5A is higher than that of the evaporation fuel in the sub-chamber activated carbon 5B, or these adsorption capacities are equivalent. Thereby, the release of the evaporation fuel from the atmosphere port 2C can be further suppressed.

[0062] (3) Also, by setting the activated carbon volume ratio as described above, the main chamber 3 becomes larger and the rigidity of the main chamber 3 decreases. Thereby, as evaporation fuel accumulates in the main chamber 3, there is a possibility that the main chamber 3 may expand. In contrast, in the above embodiment, at least one vertical rib 3J is provided on the wall portion of the main chamber 3. Thereby, since the rigidity of the main chamber 3 is improved, it is possible to suppress the main chamber 3 from expanding.

[0063] (4) Also, the vertical rib 3J is provided on the first wall portion 3H that is wider than the second wall portion 3I. Therefore, it is possible to more effectively suppress the main chamber 3 from expanding. (5) Also, by providing a plurality of vertical ribs 3J on at least two of the two first wall portions 3H and the two second wall portions 3I, the rigidity of the main chamber 3 is further improved. Therefore, it is possible to more effectively suppress the main chamber 3 from expanding.

[0064] (6) Also, according to the second embodiment, the evaporation fuel flowing out from the sub-chamber 4 can be held by the third chamber 7. Therefore, it is possible to more reliably suppress the outflow of the evaporation fuel from the atmosphere port 2C.

[0065] [5. Other Embodiments] (1) The canister 1 of the first embodiment has a main chamber 3 and a sub-chamber 4 which are integrally formed by a single housing. However, it is not limited to this, and the main chamber 3 and the sub-chamber 4 may be configured as separate parts. Specifically, for example, as shown in FIG. 7, a connection port 2D may be provided at an end of the main chamber 3 where the charge port 2A and the purge port 2B are not provided in the gas flow direction 1A. Note that the connection port 2D is connected to the third space 3C of the main chamber 3. Also, a connection port 2E may be provided at an end of the sub-chamber 4 where the atmosphere port 2C is not provided in the gas flow direction 1A. Note that the connection port 2E is connected to the second space 4B of the sub-chamber 4. And the connection port 2D of the main chamber 3 and the connection port 2E of the sub-chamber 4 may be connected by a tube 2F.

[0066] (2) A plurality of functions of one component in the above embodiment may be realized by a plurality of components, or one function of one component may be realized by a plurality of components. Also, a plurality of functions of a plurality of components may be realized by one component, or one function realized by a plurality of components may be realized by one component. Also, a part of the configuration of the above embodiment may be omitted. Also, at least a part of the configuration of the above embodiment may be added to or replaced with the configuration of another above embodiment.

Explanation of Reference Numerals

[0067] 1... Canister, 1A... Gas flow direction, 1B... First direction, 1C... Second direction, 2A... Charge port, 2B... Purge port, 2C... Atmosphere port, 3... Main chamber, 3A... First space, 3B... Second space, 3C... Third space, 3H... First wall portion, 3I... Second wall portion, 3J... Vertical rib, 3K... Horizontal rib, 4... Sub-chamber, 4A... First space, 4B... Second space, 5A... Main chamber activated carbon, 5B... Sub-chamber activated carbon, 5C... Third chamber activated carbon, 60... Water bath, 61... Container, 62... EM90 gasoline, 63... Tube, 64... Tube, 7... Third chamber.

Claims

1. A canister that adsorbs and desorbs evaporated fuel generated in a vehicle fuel tank, comprising: A charge port for taking in the evaporated fuel; A purge port for discharging the evaporated fuel; An atmosphere port opened to the atmosphere; A main chamber to which the charge port and the purge port are connected; A sub-chamber communicating with the main chamber and to which the atmosphere port is directly or indirectly connected through another chamber; Activated carbon stored in the main chamber and the sub-chamber respectively; And wherein: In the sub-chamber, the ratio L / D of the length L [mm] in the gas flow direction to the equivalent diameter D [mm] in a cross-section perpendicular to the gas flow direction is 2 or more; The ratio of the volume of the activated carbon stored in the main chamber to the volume of the activated carbon stored in the sub-chamber is more than 5.5 and not more than 10; The emission amount when the unit adsorption amount measured by the DBL test is 17.6 g / L is 100 mg or less, and the unit adsorption amount is the value obtained by dividing the weight [g] of the evaporated fuel adsorbed by the canister by the volume [L] of the activated carbon stored in the main chamber and the sub-chamber. Canister.

2. The canister according to claim 1, wherein The adsorption capacity of the evaporated fuel of the activated carbon stored in the main chamber is greater than or equal to the adsorption capacity of the evaporated fuel of the activated carbon stored in the sub-chamber. Canister.

3. The canister according to claim 1 or claim 2, further comprising: At least one rib protruding from a wall portion facing the activated carbon in the main chamber, The rib extending along the gas flow direction. Canister.

4. The canister according to claim 3, wherein The main chamber and the sub-chamber are arranged side by side along a first direction substantially orthogonal to the gas flow direction, The wall portion has two first wall portions facing each other along a second direction substantially orthogonal to the first direction and the gas flow direction, and two second wall portions facing each other along the first direction, and each of the first wall portions is wider than each of the two second wall portions. The rib is provided on the first wall portion. Canister.

5. The canister according to claim 4, wherein A plurality of the ribs are provided on at least two of the two first wall portions and the two second wall portions. Canister.

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