Canister

Abstract

To promote smoothing of a flow of fluid in a canister.SOLUTION: A canister comprises a plurality of chambers in which an adsorbent for adsorbing fuel vapor is arranged, a case member, an inflow port, an atmosphere port, and an outflow port. The case member forms a main chamber that is one of the plurality of chambers. The inflow port and the outflow port are provided in a first end part of the main chamber. The case member comprises at least one contraction part that is a wall-like part forming a region around the first end part in the main chamber. The contraction part contracts the area of a cross section orthogonal to a flow direction of fluid in the main chamber as going toward the first end part.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a canister. [Background technology]

[0002] As described in Patent Document 1, a canister is known in which a first adsorption chamber adjacent to an atmospheric port for allowing atmospheric air to flow in during purging, a second adsorption chamber, and a space located between the first and second adsorption chambers are arranged in a line. In this canister, the flow rate of the purging air is reduced when it passes through the space, so that the contact time between the adsorbent in the second adsorption chamber and the purging air is extended. This improves the desorption efficiency of fuel vapor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-019572 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the main chamber, which is equipped with a charge port communicating with the fuel tank and a purge port that discharges fuel vapor during purging, has a large volume, and as a result of the space reducing the flow rate of the purging air, there is a risk that the flow of the air will be stagnant in the main chamber.

[0005] In one aspect of the present disclosure, it is desirable to promote smooth fluid flow within the canister. [Means for solving the problem]

[0006] One aspect of the present disclosure is a canister configured to be mounted on a vehicle having an engine, the canister comprising a plurality of chambers, a case member, an inflow port, an atmospheric port, and an outflow port. An adsorbent that adsorbs fuel vapor is disposed in the chamber. The case member forms a main chamber, which is one of the plurality of chambers. The inflow port is a portion provided at a first end of the main chamber, and is configured to allow fuel vapor to flow from a fuel tank of the vehicle into the main chamber. The atmospheric port is configured to be open to the atmosphere, and is provided in a sub-chamber, which is one of the plurality of chambers. The outflow port is a portion provided at a first end of the main chamber, and is configured to allow fuel vapor adsorbed in the adsorbent to flow out toward the engine by atmospheric air flowing in from the atmospheric port. The case member has at least one reduced portion, which is a wall-shaped portion that forms a region around the first end of the main chamber. The reduced portion is configured to reduce the area of ​​a cross section perpendicular to the flow direction of the fluid in the main chamber toward the first end.

[0007] According to the above configuration, the reduced portion can improve the flow of fluid around the first end in the main chamber, which can promote a smoother flow of fluid in the canister.

[0008] In one aspect of the present disclosure, the narrowing portion may be a wall-like portion that forms a region around a first end of the main chamber where an inlet port is provided, and the cross-section of the region may be configured to narrow toward the inlet port.

[0009] According to the above-mentioned configuration, the reduced portion can improve the flow of fluid in the area around the inlet port in the main chamber, which can promote a smooth flow of fluid in the canister.

[0010] In one aspect of the present disclosure, the narrowing portion may be a wall-like portion that forms a region around a first end of the main chamber where an outlet port is provided, and the cross-section of the region may be configured to narrow toward the outlet port.

[0011] According to the above configuration, the reduced portion can improve the flow of fluid in the area around the outlet port in the main chamber, which can encourage fuel vapors accumulated in the canister to flow out smoothly from the outlet port during purging, improving desorption performance.

[0012] In one aspect of the disclosure, the reduced portion may have a portion that is inclined relative to the flow direction, and the portion may surround an area around the first end of the main chamber. According to the above configuration, the reduced portion can further improve the flow of fluid around the first end in the main chamber, which can promote a smoother flow of fluid in the canister.

[0013] In one aspect of the present disclosure, the reduction portion may extend linearly in an axial cross section, which is a cross section including an axis that is a line passing through the first end where the reduction portion is provided and that extends in the flow direction.

[0014] According to the above configuration, the reduced portion can improve the flow of fluid in the area around the first end of the main chamber, which can promote smoother flow of fluid in the canister.

[0015] In one aspect of the present disclosure, a granular adsorbent may be disposed in the main chamber. At least one void forming portion having a predetermined shape may be provided near the inner circumferential surface of the reduction portion. According to the above-mentioned configuration, a gap is easily formed between the gap forming portion and the granular adsorbent located around the gap forming portion, so that the airflow resistance inside the reduced portion can be reduced. [Brief description of the drawings]

[0016] [Figure 1] FIG. 4 is a cross-sectional view taken along the direction of fluid flow in the canister. [Diagram 2] 11 is a cross-sectional view taken along the fluid flow direction in a contracted portion of Modification 1. FIG. [Diagram 3] 11 is a cross-sectional view taken along the fluid flow direction in a contracted portion of Modification 1. FIG. [Figure 4] 11 is a cross-sectional view taken along the fluid flow direction in a contracted portion of Modification 2. FIG. [Diagram 5] FIG. 11 is a cross-sectional perspective view taken along the fluid flow direction in a contraction portion of Modification 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the embodiments of the present disclosure are not limited to the following embodiments, and various forms may be adopted as long as they fall within the technical scope of the present disclosure.

[0018] [1. Canister configuration] A canister 1 of this embodiment is mounted on a vehicle (see FIG. 1). The canister 1 has a resin case member 10 that forms the outer circumferential surface, and a main chamber 20 and an auxiliary chamber 30 are provided inside the case member 10. Adsorbents 4 for adsorbing fuel vapor are disposed in these chambers. The number of chambers in the canister 1 may be, for example, three or more.

[0019] The adsorbent 4 may be, for example, granular or powdered activated carbon, agglomerates of fibrous activated carbon, or honeycomb carbon containing activated carbon. The adsorbent 4 is not limited to activated carbon and may be made of various materials capable of adsorbing fuel vapor.

[0020] An inlet port 11, an outlet port 12, and an atmospheric port 13 are provided at an end of the case member 10. Hereinafter, the side of the case member 10 of the canister 1 on which the inlet port 11, the outlet port 12, and the atmospheric port 13 are provided will be referred to as the port side. The case member 10 also has an opening on the opposite side to the port side. The opening is closed by a lid member 14. Hereinafter, the side opposite the port side (in other words, the side on which the lid member 14 is provided) will be referred to as the lid side.

[0021] [2.Main room] The main chamber 20 forms a space of a substantially rectangular parallelepiped shape extending from the port side to the lid side, and an inlet port 11 and an outlet port 12 that connect the main chamber 20 to the outside of the canister 1 are provided at the end on the port side (hereinafter, the first end F) (see FIG. 1). The shape of the space in the main chamber 20 is not limited to a substantially rectangular parallelepiped shape, and may be, for example, a substantially cylindrical shape. In addition, the end on the lid side of the main chamber 20 (hereinafter, the second end S) is connected to a communication passage 15. In the main chamber 20, fuel vapor and purge air (hereinafter, also referred to as fluid) flow along the direction in which the first end F and the second end S face each other. The main chamber 20 is formed by the case member 10, and includes a main body portion 21 and two reduced portions 22.

[0022] The main body portion 21 extends from the second end S of the main chamber 20 toward the port side, and is a wall-like portion that surrounds the main chamber 20 from the sides. The two reduced sections 22 are wall-like portions that expand from the port side end of the main body 21 toward the port side and form the main chamber 20. Each reduced section 22 is configured to reduce the area of ​​a cross section perpendicular to the fluid flow direction in the main chamber 20 (hereinafter, referred to as an orthogonal cross section) toward the port side (in other words, toward the first end F). The two reduced sections 22 are provided corresponding to the periphery of the inflow port 11 and the periphery of the outflow port 12, respectively, and laterally surround the area around the corresponding port in the main chamber 20, reducing the orthogonal cross section of that area toward the corresponding port.

[0023] The two reduction sections 22 are provided side by side at the port side end of the main body section 21 in a direction perpendicular to the fluid flow direction, more specifically, along the direction in which the main chamber 20 and the auxiliary chamber 30 are aligned. A first end F of the main chamber 20 is formed by the port side ends of the two reduction sections 22. An inflow port 11 and an outflow port 12 are provided at the end of each reduction section 22 (in other words, each first end F).

[0024] A filter 23 is provided at each first end F of the main chamber 20, and a filter 24 is disposed at the second end S. An adsorbent 4 is disposed between the two filters 23 on the port side and the filter 24 on the lid side. A permeable porous plate 25 is disposed between the filter 24 on the lid side and the communication passage 15, and a coil spring 16 is disposed between the porous plate 25 and the lid member 14. The coil spring 16 presses the porous plate 25 toward the port side.

[0025] [3. Antechamber] The auxiliary chamber 30 is adjacent to the main chamber 20, has a smaller volume than the main chamber 20, and has a long and thin cylindrical shape extending from the lid side to the port side (see FIG. 1). The shape of the auxiliary chamber 30 is not limited to a cylindrical shape, and may be, for example, a rectangular prism shape. An atmospheric port 13 that connects the auxiliary chamber 30 to the outside of the canister 1 is provided at the port side end (hereinafter, first end F) of the auxiliary chamber 30. Filters 31 and 32 are arranged at the first end F and the lid side end (hereinafter, second end S) of the auxiliary chamber 30, respectively, and an adsorbent 4 is arranged between the filters 31 and 32. In addition, the second end S of the auxiliary chamber 30 is connected to the communication passage 15, and a porous plate 33 is arranged between the filter 32 on the lid side and the communication passage 15. In addition, similar to the main chamber 20, the porous plate 33 is pressed toward the port side by a coil spring 17 between the porous plate 33 and the lid member 14.

[0026] Furthermore, the communication passage 15 is provided along the cover member 14, and connects the main chamber 20 and the auxiliary chamber 30. Therefore, inside the canister 1, the fluid can travel between the main chamber 20 and the auxiliary chamber 30 via the communication passage 15.

[0027] In the sub-chamber 30, similarly to the main chamber 20, the fluid flows in the direction in which the first end F and the second end S face each other. [4. Port] The inlet port 11 is connected to a fuel tank of a vehicle engine (see FIG. 1). Fuel vapor generated in the fuel tank flows into the canister 1 through the inlet port 11 and is adsorbed by the adsorbent 4 in each chamber. As a result, fuel is accumulated inside the canister 1.

[0028] The outlet port 12 is connected to an intake pipe of the engine of the vehicle, and the atmospheric port 13 is connected to the outside of the vehicle and is open to the atmosphere. The negative intake pressure of the engine causes the atmosphere (in other words, purge air) to flow into the canister 1 via the atmospheric port 13. The inflow of the purge air causes the fuel vapor adsorbed in the adsorbent 4 to be desorbed, and the desorbed fuel vapor flows out from the outlet port 12 toward the intake pipe together with the purge air. This causes a purge to remove the fuel vapor adsorbed in the adsorbent 4, and the adsorbent 4 is regenerated.

[0029] [5. Details of the reduced area] Each of the reduction sections 22 is provided adjacent to the first end F, and is formed in a tapered shape, for example (see FIG. 1). Specifically, the orthogonal cross section of each of the reduction sections 22 is substantially circular. Of course, the shape of the orthogonal cross section of the reduction section 22 is not limited to this, and may be a shape other than a substantially circular shape, for example, a substantially elliptical shape or a substantially polygonal shape. The axial cross section of each of the reduction sections 22 extends linearly while being inclined with respect to the fluid flow direction so as to approach the axis A toward the port side. The portion of the reduction section 22 inclined with respect to the fluid flow direction is formed so as to surround the area around the first end F in the main chamber 20 where the reduction section 22 is provided. The axial cross section means a cross section that is parallel to the axis A and includes the axis A. The axis A is a virtual straight line that passes through the inflow port 11 or the outflow port 12 corresponding to the reduction section 22 (in other words, the first end F) and extends in the fluid flow direction.

[0030] The reduction section 22 may be provided corresponding to only one of the inflow port 11 and the outflow port 12. In this case, the area around the inflow port 11 or the outflow port 12 where the reduction section 22 is not provided may be surrounded by a cylindrical portion whose orthogonal cross-sectional shape is approximately constant (in other words, extending approximately straight).

[0031] [6. Variation 1] The reduction section 22 may be provided at a position away from the first end F where the inflow port 11 and the outflow port 12 are provided (see FIG. 2). Specifically, for example, the reduction section 22 and the straight section 26 may be provided around the first end F.

[0032] The reduced portion 22 is tapered, and for example, the ends on the lid side and the port side are rounded. The straight section 26 is a section that extends along the fluid flow direction in the axial cross section. In other words, the straight section 26 is tubular and extends substantially straight. The orthogonal cross section of the straight section 26 is substantially constant and has substantially the same shape as the end face that forms the first end F of the main chamber 20. The straight section 26 extends from the first end F toward the lid, and the reduction section 22 is provided at the end of the straight section 26 on the lid side. The end of the reduction section 22 on the lid side is connected to the main body 21.

[0033] Furthermore, the shape of the reduction portion 22 is not limited to a tapered shape and can be determined appropriately. Furthermore, a plurality of reduction portions 22 may be provided around the first end F. Specifically, as shown in Fig. 3, as an example, the reduction portions 22A, 22B may be stepped portions that expand in a direction substantially perpendicular to the fluid flow direction. In other words, the inclination of the reduction portions 22A, 22B with respect to the fluid flow direction may be substantially 90°.

[0034] 3, two stepped first and second reduced portions 22A, 22B and first to third linear portions 26A to 26C may be provided around the first end F. That is, the first linear portion 26A is provided so as to extend from the first end F of the main chamber 20 toward the lid side, and the first reduced portion 22A is provided at the end of the first linear portion 26A on the lid side. Furthermore, the second linear portion 26B is provided so as to extend from the end of the outer periphery side of the first reduced portion 22A toward the lid side, and the second reduced portion 22B is provided at the end of the second linear portion 26B on the lid side. Furthermore, the third linear portion 26C is provided so as to extend from the end of the outer periphery side of the second reduced portion 22B toward the lid side, and the end of the third linear portion 26C on the lid side is connected to the main body portion 21.

[0035] [7. Variation 2] The reduction section 22 may be provided corresponding to the inflow port 11 and the outflow port 12 (see FIG. 4). In other words, the main chamber 20 may be provided with one reduction section 22, and the reduction section 22 may be provided so as to extend from one first end F of the main chamber 20 where the inflow port 11 and the outflow port 12 are provided, toward the lid side.

[0036] In FIG. 4, as an example, the reduced portion 22 is tapered and provided adjacent to the first end F. However, the shape, position, and number of the reduced portion 22 can be determined as appropriate. That is, similar to the first modification, the reduced portion 22 may be provided away from the first end F, or may have a stepped shape. Also, similar to the first modification, a plurality of reduced portions 22 may be provided around the first end F together with straight portions.

[0037] [8. Variation 3] While the granular adsorbent 4 is disposed in the main chamber 20, at least one void-forming portion having a predetermined shape may be provided near the inner circumferential surface of the reduction portion 22. The granular adsorbent 4 may be, for example, pellets of granular activated carbon. The pellets may have various shapes, such as a substantially cylindrical shape or a spherical shape. In addition, when two reduction portions 22 are provided in the main chamber 20, the void-forming portion may be provided in both or one of the two reduction portions 22.

[0038] Specifically, as an example, as shown in FIG. 5, the plurality of gap forming portions 27 may be provided so as to protrude from the inner peripheral surface of the tapered reduction portion 22 toward the axis A of the port adjacent to the reduction portion 22. Each gap forming portion 27 extends along the fluid flow direction, and a cross section perpendicular to the fluid flow direction is, for example, rectangular. That is, each gap forming portion 27 is plate-shaped. Moreover, each gap forming portion 27 is arranged at approximately regular intervals so as to go around the axis A. Moreover, the plurality of gap forming portions 27 may be made of resin like the reduction portion 22 and the case member 10, and may be formed integrally with the reduction portion 22 and the case member 10.

[0039] Of course, the shape and arrangement of each gap forming portion 27 may be determined appropriately. Specifically, for example, each gap forming portion 27 may be a rib-shaped portion protruding from the inner circumferential surface of the reduction portion 22 and extending in the fluid flow direction. Also, each gap forming portion 27 may extend in a direction different from the fluid flow direction. Also, each gap forming portion 27 may be a rod-shaped portion protruding from the inner circumferential surface of the reduction portion 22. Each gap forming portion 27 may be provided at a specific location on the inner circumferential surface without going around the axis A.

[0040] Furthermore, in the case where the straight portion 26 is provided adjacent to the contraction portion 22, each void forming portion 27 may be provided so as to straddle the contraction portion 22 and the straight portion 26. Moreover, the top of each gap forming portion 27 extends along the boundary of the front region 20A. The front region 20A means a region extending from the end face forming the outlet port 12 or the first end F where the outlet port 12 is provided in the main chamber 20 toward the lid side along the fluid flow direction. The front region 20A is a columnar region in which the cross section perpendicular to the extension direction has substantially the same shape as the end face. Of course, the shape is not limited to this, and the shape of the top of each gap forming portion 27 can be determined appropriately.

[0041] The plurality of gap forming portions 27 may be configured as separate members from the reduction portion 22. That is, the plurality of gap forming portions 27 may be formed separately from the reduction portion 22 and assembled to the inner circumferential surface of the reduction portion 22 or disposed in the vicinity of the inner circumferential surface. Similarly, one gap forming portion may be provided on the inner circumferential surface of the reduction portion 22. Similarly, at least one gap forming portion may be provided in the reduction portions 22 of the first and second modifications.

[0042] [9. Effects] (1) In a chamber in which a port is provided in a canister, the region where the fluid flow is relatively good is thought to spread out in a roughly fan-like shape from the port in the direction of the fluid flow. Therefore, in the vicinity of the port in the chamber, the fluid flow is stagnated in the region around the side wall that laterally surrounds the chamber, and this region may become a dead space where the adsorbent does not adequately adsorb and desorb fuel vapor.

[0043] In contrast, according to the above embodiment, by providing the reduced portion 22 at the first end F of the main chamber 20, the dead space can be reduced and the flow of fluid around the first end F in the main chamber 20 can be improved. This can promote smoother flow of fluid in the canister 1. This improves the desorption performance of the fuel vapor adsorbed in the adsorbent. Furthermore, the improved desorption performance allows the fuel vapor to be efficiently accumulated using a small amount of the adsorbent 4, thereby improving the adsorption performance of the fuel vapor.

[0044] (2) Furthermore, during purging, it is believed that the flow velocity of the purge air decreases around the outlet port 12 in the main chamber 20. In response to this, by providing the reduced section 22 around the outlet port 12, it is possible to suppress the decrease in the flow velocity of the purge air around the outlet port 12 in the main chamber 20. As a result, during purging, it is possible to encourage the fuel vapor accumulated in the canister 1 to flow out smoothly from the outlet port 12, improving the desorption performance.

[0045] (3) Furthermore, the inclined portion of the reduced portion 22 surrounds the area around the first end F of the main chamber 20 where the corresponding port is provided. This can further improve the flow of fluid around the first end F of the main chamber 20. This can promote smoother flow of fluid inside the canister 1.

[0046] (4) Furthermore, since the reduced portion 22 is tapered, the flow of fluid around the first end F in the main chamber 20 can be improved. This can promote smoother flow of fluid within the canister 1.

[0047] (5) Furthermore, by providing the void forming portion 27 in the reduction portion 22, a void can be formed around the void forming portion 27 and the granular adsorbent in contact with the void forming portion 27. This makes it possible to reduce the airflow resistance inside the reduction portion 22.

[0048] [10. Other embodiments] (1) In the above embodiment, the main chamber 20 and the reduced portion 22 are formed by the case member 10 that forms the outer peripheral surface of the canister 1. However, this is not limited thereto, and the canister 1 may have an outer case that forms the outer peripheral surface, and a case member that is an inner case disposed inside the outer case. The main chamber having a reduced portion similar to that of the above embodiment may be formed by the case member that is the inner case.

[0049] The canister 1 may be provided with a plurality of main chambers arranged in the fluid flow direction. In this case, the main chambers adjacent to the inflow port 11 and the outflow port 12 may be formed with the reduced portions 22 similar to those in the above embodiment.

[0050] (2) In the above embodiment, the portion of the reduction section 22 that is inclined with respect to the fluid flow direction is formed so as to surround the area of ​​the main chamber 20 around the first end F where the corresponding port is provided. However, the inclined portion does not have to surround the area. That is, the reduction section may be provided with an inclined portion that is inclined with respect to the fluid flow direction and a non-inclined portion that extends substantially straight along the fluid flow direction. Even with such a reduction section, the orthogonal cross section of the area of ​​the main chamber 20 that is surrounded by the reduction section can be reduced toward the corresponding port.

[0051] (3) Multiple functions possessed by one component in the above embodiments may be realized by multiple components, or one function possessed by one component may be realized by multiple components. Also, multiple functions possessed by multiple components may be realized by one component, or one function realized by multiple components may be realized by one component. Also, part of the configuration of the above embodiments may be omitted. Also, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments.

[0052] [11. Technical Concepts Disclosed in the Present Specification] [Item 1] A canister configured to be mounted on a vehicle having an engine, A plurality of chambers in which an adsorbent material for adsorbing fuel vapor is disposed; A case member that forms a main chamber that is one of the plurality of chambers; an inlet port at a first end of the main chamber configured to allow fuel vapor to enter the main chamber from a fuel tank of the vehicle; an atmospheric port configured to be open to the atmosphere and provided in a sub-chamber that is one of the plurality of chambers; an outlet port that is provided at the first end of the main chamber and configured to allow the fuel vapor adsorbed in the adsorbent to flow out toward the engine by the atmosphere flowing in from the atmosphere port; the case member has at least one reduced portion which is a wall-like portion that forms a region around the first end of the main chamber, The narrowing portion is configured to narrow a cross-sectional area perpendicular to a flow direction of the fluid in the main chamber toward the first end. Canister.

[0053] [Item 2] Item 1. A canister according to item 1, The contracting portion is a wall-like portion that forms a region around the first end portion of the main chamber where the inflow port is provided, and is configured to contract the cross section of the region toward the inflow port. Canister.

[0054] [Item 3] The canister according to item 1 or 2, The contracting portion is a wall-like portion that forms a region around the first end of the main chamber where the outlet port is provided, and is configured to contract the cross section of the region toward the outlet port. Canister.

[0055] [Item 4] A canister according to any one of items 1 to 3, The reduced portion has a portion inclined with respect to the flow direction, the portion surrounding an area around the first end of the main chamber. Canister.

[0056] [Item 5] A canister according to any one of items 1 to 4, The reduced portion extends linearly in an axial cross section that is a cross section including an axis that is a line passing through the first end portion at which the reduced portion is provided and that is a line extending in the flow direction. Canister.

[0057] [Item 6] A canister according to any one of items 1 to 5, A granular adsorbent is disposed in the main chamber, At least one gap forming portion having a predetermined shape is provided near the inner circumferential surface of the reduced portion. Canister. [Explanation of symbols]

[0058] 1...canister, 10...case member, 11...inlet port, 12...outlet port, 13...atmospheric port, 20...main chamber, 21...main body portion, 22...reduced portion, 26...straight portion, 27...gap forming portion, 30...auxiliary chamber, 4...adsorbent, F...first end, S...second end.

Claims

1. A canister configured to be mounted on a vehicle having an engine, A plurality of chambers in which an adsorbent material for adsorbing fuel vapor is disposed; a case member that forms a main chamber that is one of the plurality of chambers; an inlet port at a first end of the main chamber configured to allow fuel vapor to enter the main chamber from a fuel tank of the vehicle; an atmospheric port configured to be open to the atmosphere and provided in a sub-chamber that is one of the plurality of chambers; an outlet port that is provided at the first end of the main chamber and configured to allow the fuel vapor adsorbed in the adsorbent to flow out toward the engine by the atmosphere flowing in from the atmosphere port; the case member has at least one reduced portion which is a wall-like portion that forms a region around the first end of the main chamber, The reducing portion is configured to reduce a cross-sectional area perpendicular to a flow direction of the fluid in the main chamber toward the first end. Canister.

2. 2. The canister of claim 1, The contracting portion is a wall-like portion that forms a region around the first end of the main chamber where the inflow port is provided, and is configured to contract the cross section of the region toward the inflow port. Canister.

3. 3. The canister according to claim 1 or 2, The contracting portion is a wall-like portion that forms a region around the first end of the main chamber where the outflow port is provided, and is configured to contract the cross section of the region toward the outflow port. Canister.

4. 3. The canister according to claim 1 or 2, The reduced portion has a portion inclined with respect to the flow direction, the portion surrounding a region of the main chamber around the first end. Canister.

5. 3. The canister according to claim 1 or 2, The reduced portion extends linearly in an axial cross section that is a cross section including an axis that is a line passing through the first end portion at which the reduced portion is provided and that is a line extending in the flow direction. Canister.

6. 3. The canister according to claim 1 or 2, A granular adsorbent is disposed in the main chamber, At least one gap forming portion having a predetermined shape is provided near the inner circumferential surface of the reduced portion. Canister.

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