Canister

A passage through which a fluid can flow is formed in a canister. A first end of the passage includes an evaporated fuel introducing port and a purge port, and a second end of the passage includes an atmosphere release port. A first chamber and a second chamber are provided at the passage. The first chamber accommodates a first adsorbent, and the second chamber accommodates a second adsorbent, both capable of adsorbing and desorbing evaporated fuel. The passage is horizontal when the canister is mounted on the vehicle. A flow dividing plate including a plurality of communicating holes is provided in the second chamber, close to the atmosphere release port. When the canister is mounted, an area of the communicating holes per unit area on a surface of the flow dividing plate is larger at a lower side of the flow dividing plate than at an upper side.

TECHNICAL FIELD

The present invention relates to a canister mounted on a vehicle, such as an automobile, and configured to adsorb and desorb evaporated fuel.

BACKGROUND ART

PTL 1 discloses a canister configured to adsorb and desorb evaporated fuel. This canister is configured such that: a passage through which a fluid can flow is formed in the canister; a first end of the passage is provided with an evaporated fuel introducing port through which evaporated fuel from a fuel tank is introduced to the canister and a purge port through which the canister communicates with an intake passage of an engine; and a second end of the passage is provided with an atmosphere release port communicating with the atmosphere. Further, a first chamber and a second chamber are provided at the passage in this order from the first end side. The first chamber accommodates a first adsorbent capable of adsorbing and desorbing the evaporated fuel, and the second chamber accommodates a second adsorbent capable of adsorbing and desorbing the evaporated fuel.

In many cases, the canister is mounted on a vehicle in such a posture that the passage extends horizontally as disclosed in PTL 2 due to, for example, an in-vehicle layout.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

The canister having configurations described in PTL 1 generally performs such purge that by utilizing, for example, negative pressure of the intake passage during an operation of the engine, fuel components adsorbed by the adsorbents in the first and second chambers are desorbed and then introduced into the intake passage.

During the purge, the fuel components adsorbed by the adsorbents of the first and second chambers move toward the intake passage by the negative pressure of the intake passage. For example, the fuel adsorbed by the second adsorbent of the second chamber moves toward the first chamber. When the engine stops, and the purge is terminated, the negative pressure of the intake passage disappears. With this, the fuel components adsorbed by (remaining in) the adsorbents in the first and second chambers do not move toward the intake passage but move to a lower side in the adsorbents by gravity.

When the purge is not being performed as above, advancing force which tries to keep a fuel component concentration uniform acts in the adsorbents of the first and second chambers. For example, when the concentration of the fuel components remaining in the second adsorbent of the second chamber becomes a certain concentration or more, the fuel components advance toward the atmosphere release port in the second adsorbent. The fuel components which have reached an end portion, close to the atmosphere release port, of the second adsorbent are released through the atmosphere release port in some cases.

An object of the present invention is to provide a canister capable of suppressing release of fuel components to the atmosphere.

Solution to Problem

A first aspect of the present invention in the present application is a canister mounted on a vehicle and configured to adsorb and desorb evaporated fuel, wherein: a passage through which a fluid flows is formed in the canister; a first end of the passage includes an evaporated fuel introducing port through which the evaporated fuel from a fuel tank is introduced into the canister and a purge port through which the canister communicates with an intake passage of an engine; a second end of the passage includes an atmosphere release port communicating with an atmosphere; a first chamber and a second chamber are provided at the passage in this order from the first end side, the first chamber accommodating a first adsorbent configured to adsorb and desorb the evaporated fuel, the second chamber accommodating a second adsorbent configured to adsorb and desorb the evaporated fuel; the passage is configured to extend substantially horizontally when the canister is mounted on the vehicle; a flow dividing plate including a plurality of communicating holes is provided at a side of the second adsorbent in the second chamber, the side being close to the atmosphere release port; and when the canister is mounted on the vehicle, an area of the communicating holes per unit area on a surface of the flow dividing plate is larger at a lower side of the flow dividing plate than at an upper side of the flow dividing plate.

A second aspect of the present invention in the present application is configured such that in the first aspect of the present invention, an air layer is provided between the flow dividing plate and an end portion of the second adsorbent, the end portion being close to the atmosphere release port.

A third aspect of the present invention in the present application is configured such that in the first or second aspect of the present invention, the second adsorbent is configured such that an evaporated fuel adsorption ability is higher at a portion, close to the atmosphere release port in an extending direction of the passage, of the second adsorbent than at a portion, far from the atmosphere release port in the extending direction of the passage, of the second adsorbent.

Advantageous Effects of Invention

According to the first aspect of the present invention in the present application, the flow dividing plate including the plurality of communicating holes is provided at the side, close to the atmosphere release port, of the second adsorbent in the second chamber, and when the canister is mounted on the vehicle, the area of the communicating holes per unit area on the surface of the flow dividing plate is larger at the lower side of the flow dividing plate than at the upper side of the flow dividing plate. Therefore, ventilation resistance is relatively lower at the lower side of the second chamber than at the upper side of the second chamber. On this account, the evaporated fuel adsorbed by the second adsorbent accommodated in the second chamber is more easily desorbed at the lower side during the purge, and the amount of evaporated fuel remaining is smaller at the lower side. To be specific, the fuel component concentration in the second adsorbent is lower at the lower side by the purge. It should be noted that the wording “the passage is configured to extend substantially horizontally” in the first aspect of the present invention includes, for example, a case where a tilt angle of a tube axis of the passage with respect to a horizontal plane is between −30° and +30°.

With this, even when the fuel components adsorbed by the upper side of the second adsorbent move to the lower side by gravity during the stop of the engine, the lower side of the second adsorbent has an enough adsorption capacity, so that the fuel components moving toward the lower side can be adsorbed by the lower side of the second adsorbent. Therefore, as compared to conventional cases, it is possible to delay the start of the advancement of the fuel components in the second adsorbent toward the atmosphere release port. With this, a time from when the engine stops until when the fuel components reach the end portion, close to the atmosphere release port, of the adsorbent is increased. Therefore, the release of the fuel components to the atmosphere is suppressed.

According to the second aspect of the present invention in the present application, the air layer is provided between the flow dividing plate and the end portion, close to the atmosphere release port, of the second adsorbent. With this, even when the flow dividing plate is provided, the deterioration of the use efficiency of the second adsorbent can be suppressed. To be specific, if the air layer is not provided between the flow dividing plate and the end portion, close to the atmosphere release port, of the second adsorbent, the air flowing from the atmosphere release port does not adequately flow into the second adsorbent contacting portions other than the communicating holes of the flow dividing plate. As a result, there is a possibility that the use efficiency of the second adsorbent deteriorates. However, according to the present invention, the air layer is provided between the flow dividing plate and the end portion, close to the atmosphere release port, of the second adsorbent. Therefore, the air flowing from the atmosphere release port easily flows into the second adsorbent through the end portion, close to the atmosphere release port, of the second adsorbent. On this account, even when the flow dividing plate is provided, the deterioration of the use efficiency of the second adsorbent can be suppressed.

According to the third aspect of the present invention in the present application, the second adsorbent is configured such that the evaporated fuel adsorption ability is higher at the portion, close to the atmosphere release port in the extending direction of the passage, of the second adsorbent than at the portion, far from the atmosphere release port in the extending direction of the passage, of the second adsorbent. With this, the advancement of the remaining fuel components toward the atmosphere release port in the second adsorbent by capillarity becomes slower as the remaining fuel components get close to the atmosphere release port. Therefore, the time from when the engine stops until when the fuel components reach the end portion, close to the atmosphere release port, of the second adsorbent can be further increased. Thus, the release of the fuel components to the atmosphere can be suppressed more satisfactorily.

DESCRIPTION OF EMBODIMENTS

A canister1of Embodiment 1 of the present invention will be explained.FIG. 1is a perspective view showing an appearance of the canister of Embodiment 1 of the present invention. As shown inFIG. 1, the canister1includes a casing10. The casing10has a bottomed tubular shape. An evaporated fuel introducing port11, a purge port12, and an atmosphere release port13are formed on a bottom wall of the casing10, the bottom wall being located at a first end side in a tube axis direction. A passage through which a fluid can flow is formed in the canister1as will be described later in detail. A first end of the passage is provided with the evaporated fuel introducing port11and the purge port12, and a second end of the passage is provided with the atmosphere release port13communicating with the atmosphere. Further, a first chamber and a second chamber are provided at the passage in this order from the first end side. The first chamber accommodates a first adsorbent capable of adsorbing and desorbing evaporated fuel, and the second chamber accommodates a second adsorbent capable of adsorbing and desorbing the evaporated fuel. In other words, the first chamber and the second chamber constitute a part of the entire passage of the canister1. An extending direction of the passage in each of the first and second chambers substantially coincides with the tube axis direction.

The canister1according to the present embodiment is mounted on a vehicle, such as an automobile.FIG. 2is a bottom view of the vehicle on which the canister1of Embodiment 1 of the present invention is mounted.FIG. 3is a rear view of the vehicle on which the canister1of Embodiment 1 of the present invention is mounted. As shown inFIG. 2, a pair of left and right side frames41L and41R extend from a front portion of the vehicle to a rear portion of the vehicle at respective left and right side portions of the vehicle. An engine30is mounted between the left and right side frames41L and41R at the front portion of the vehicle. An exhaust pipe39extends from the engine30to the rear portion of the vehicle and is connected to a silencer40. A fuel tank31is arranged at the rear portion of the vehicle and at a lower surface side of a floor panel. The canister1is arranged behind the fuel tank31, in the vicinity of a front portion of the silencer40, and at a vehicle width direction inner side of the left side frame41L. The canister1is arranged in the vicinity of the front portion of the silencer40for the purpose of: warming up the canister1by the silencer40; and facilitating introduction of warmed air by the canister1. The canister1is arranged horizontally such that the tube axis direction extends substantially horizontally. Further, as shown inFIGS. 2 and 3, the canister1is arranged at a position substantially the same in height as the fuel tank31so as to utilize a space under the floor panel. A purge passage35connecting the engine30(an intake passage34of the engine30) and the purge port12of the canister1extends along the left side frame41L in a vehicle forward/rearward direction. An evaporated fuel introducing passage32connecting the fuel tank31and the evaporated fuel introducing port11of the canister1extends between the fuel tank31and the evaporated fuel introducing port11in the forward/rearward direction. An atmosphere release pipe38connected to the atmosphere release port13of the canister1extends to a space located in a rear fender and behind a left rear wheel42L out of left and right rear wheels42L and42R.

FIG. 3is a rear view of the vehicle on which the canister1of Embodiment 1 of the present invention is mounted. The canister1is arranged at a position substantially the same in height as the fuel tank31so as to effectively utilize a space under the floor panel.

FIG. 4is a schematic configuration diagram of an evaporated fuel processing system including the canister1of Embodiment 1 of the present invention. The evaporated fuel processing system is a system configured to process the evaporated fuel generated in the fuel tank31. An evaporated fuel gas containing the evaporated fuel generated in the fuel tank31is introduced into the canister1through the evaporated fuel introducing passage32and the evaporated fuel introducing port11, and the introduced evaporated fuel is adsorbed by the adsorbents in the canister1. The purge port12is connected to the intake passage34of the engine30through the purge passage35. When pressure in the intake passage34becomes negative pressure by opening/closing operations of a throttle valve37during an operation of the engine30, air is introduced into the canister1through the atmosphere release port13. With this, fuel components which have been adsorbed by the adsorbents are desorbed, and the desorbed fuel components are introduced into a combustion chamber of the engine30through the intake passage34and utilized as combustion fuel. The amount of evaporated fuel introduced into the intake passage34by the purge can be controlled by controlling an opening degree of a purge valve36. Further, the amount of evaporated fuel introduced into the canister1can be controlled by controlling an opening degree of an evaporated fuel introducing valve33. The opening degrees of these valves are controlled by an engine controller (ECU (not shown)), not shown, based on, for example, an operation state of the engine30.

FIG. 5is a sectional view of the canister1of Embodiment 1 of the present invention. As shown inFIG. 5, the canister1includes the casing10. The casing10includes a bottomed tubular casing main body10A and a lid10B configured to close an opening end surface of the casing main body10A.

The evaporated fuel introducing port11, the atmosphere release port13, and the purge port12are formed at a canister outer side of a bottom plate10xof the casing main body10A.

First and second partition walls14and15projecting in the tube axis direction in a space of the casing main body10A are formed at a canister inner side of the bottom plate10xlocated at a front portion of the casing main body10A. A tip end portion of the first partition wall14extends to the vicinity of the lid10B. The first partition wall14divides an inside of the casing main body10A into a first chamber21communicating with the purge port12and the evaporated fuel introducing port11and a second chamber22communicating with the atmosphere release port13. A projection amount of the second partition wall15is smaller than a projection amount of the first partition wall14. The first partition wall14divides a space of the first chamber21, which space is located at the first end side in the tube axis direction, into two spaces that are a space close to the evaporated fuel introducing port11and a space close to the purge port12.

The first chamber21accommodates a ventilation plate54, a filter plate53, a first adsorbent51, a filter plate53, and a ventilation plate54in this order from a side close to the bottom plate10xof the casing main body10A. A stopper16projecting toward an inner side of the first chamber21in the vicinity of the bottom plate10xof the casing main body10A is formed on a tubular wall of the casing main body10A and the first partition wall14, and springs55are interposed between the ventilation plate54and the lid10B of the casing10. The springs55press a flow dividing plate62, the filter plate53, the first adsorbent51, the filter plate53, and the ventilation plate54toward the stopper16. Therefore, regarding the ventilation plates54, the filter plates53, and the first adsorbent51, adjacent members press against each other, so that any gap is not formed between the members or between the first adsorbent51and the casing10. According to the above configuration, by inserting the above members into the first chamber21in the above order through an opening of the casing main body10A, this structure can be easily realized.

The first adsorbent51adsorbs and desorbs the evaporated fuel generated in the fuel tank31. For example, activated carbon capable of adsorbing and desorbing the evaporated fuel can be utilized as the first adsorbent51. For example, used as the activated carbon for the first adsorbent51is activated carbon having a pellet shape (for example, having a diameter of 2 mm and an axial length of 4 mm), a peak of a distribution of volumes of pore sizes of the activated carbon being around 5 nm.

The filter plate53is formed by, for example, non-woven fabric. The filter plate53prevents the activated carbon, finely crushed by vibrations and the like, from getting into the passages through the ports.

The ventilation plate54is, for example, a latticed plate member including a large number of through holes54a. The ventilation plate54is formed by, for example, resin.

A space is provided between the ventilation plate54of the first chamber21and the lid10B, and a space is provided between the ventilation plate64of the second chamber22and the lid10B. A gap is provided between the lid10B and an end portion of the first partition wall14, the end portion being close to the lid10B. These spaces and gap constitute a communicating portion T through which the first chamber21and the second chamber22communicate with each other.

The second chamber22accommodates a flow dividing plate62, a filter plate63, a second adsorbent61, a filter plate63, and a ventilation plate64in this order from the side close to the bottom plate10xof the casing main body10A. A stopper16projecting toward an inner side of the second chamber22in the vicinity of the bottom plate10xof the casing main body10A is formed on the tubular wall of the casing main body10A and the first partition wall14, and a spring65is interposed between the ventilation plate64and the lid10B of the casing10. The spring65presses the ventilation plate64toward the stopper16. Therefore, regarding the ventilation plate64, the filter plates63, and the second adsorbent61, adjacent members press against each other, so that any gap is not formed between the members or between the second adsorbent61and the casing10. According to the above configuration, by inserting the above members into the second chamber22in the above order through the opening of the casing main body10A, this structure can be easily realized.

The second adsorbent61adsorbs and desorbs the evaporated fuel generated in the fuel tank31. For example, activated carbon capable of adsorbing and desorbing the evaporated fuel can be utilized as the second adsorbent61. More specifically, utilized as the second adsorbent61is the activated carbon which is lower in adsorption ability but higher in desorption performance than the first adsorbent51. This is because: the second adsorbent61needs to adsorb fuel, and at the same time, easily desorb the adsorbed fuel component during the purge; whereas the first adsorbent51needs to adsorb fuel as much as possible, and at the same time, hold the adsorbed fuel and prevents the movement of the fuel toward the second chamber22as much as possible.

For example, used as the activated carbon for the second adsorbent61is activated carbon having a pellet shape having a larger particle diameter than the first adsorbent51or a monolith shape, a peak of a distribution of volumes of pore sizes of the activated carbon being around 1,000 nm.

The filter plate63is formed by, for example, non-woven fabric. The filter plate63prevents the activated carbon, finely crushed by vibrations and the like, from getting into the passages through the ports.

The ventilation plate64is, for example, a latticed plate member including a large number of through holes64a. The ventilation plate64is formed by, for example, resin.

FIG. 6is a sectional view taken along line A-A ofFIG. 5.FIG. 7is a front view of the flow dividing plate62of the canister1of Embodiment 1 of the present invention. The flow dividing plate62is formed by, for example, resin and includes a plurality of communicating holes62a. A fluid can flow through the communicating holes62aof the flow dividing plate62. The plurality of communicating holes62aof the flow dividing plate62are formed such that when the canister1is mounted on the vehicle, an area of the communicating holes per unit area on the surface of the flow dividing plate62is larger at a lower side of the flow dividing plate62than at an upper side of the flow dividing plate62. In the example ofFIG. 7, the communicating holes62aare formed at regular intervals in an upward/downward direction and a leftward/rightward direction, and the diameters of the communicating holes62aare larger at the lower side of the flow dividing plate62than at the upper side of the flow dividing plate62. With this, the area of the communicating holes per unit area on the surface of the flow dividing plate62is larger at the lower side of the flow dividing plate62than at the upper side of the flow dividing plate62. For example, when the area at the upper side is set to 1, the area at the lower side is set to about 1.5 to 3. If an area ratio is excessively increased, a difference between flow velocities at the upper and lower sides becomes large, and there is a possibility that the desorption of the second adsorbent61is not adequately performed at the upper side where the flow velocity is low.

It should be noted that the shape of each communicating hole62aof the flow dividing plate62inFIG. 6is a circular shape. However, the shape of each communicating hole62aof the flow dividing plate62does not have to be a circular shape and may be a triangular shape, a quadrangular shape, a pentagonal shape, an oval shape, or any other shape as long as the area of the communicating holes per unit area on the surface of the flow dividing plate62is larger at the lower side of the flow dividing plate62than at the upper side of the flow dividing plate62.

Further, the flow dividing plate62is provided only at a side of the second adsorbent61in the second chamber22, the side being close to the atmosphere release port13. However, in the present invention, the flow dividing plate62may also be provided at a side of the second adsorbent61, the side being far from the atmosphere release port13. In this case, for example, a flow dividing plate62equivalent to the flow dividing plate62located at the side close to the atmosphere release port13may be provided instead of the ventilation plate64located at the side, far from the atmosphere release port13, of the second adsorbent61.

It should be noted that it is unnecessary to provide a flow dividing plate in the first chamber21. The flow dividing plate deflects the flow of the fluid. Therefore, if the flow dividing plate is provided in the first chamber21, there is a possibility that the flow dividing plate influences the flow of the fluid toward two ports that are the evaporated fuel introducing port11and the purge port12.

The filter plate63formed by the non-woven fabric is provided between the flow dividing plate62and an end portion of the second adsorbent61, the end portion being close to the atmosphere release port13. The filter plate63serves as an air layer through which a fluid can flow.

Actions

Actions of the canister1of the present embodiment will be explained. For example, during fueling or parking, the evaporated fuel gas containing the evaporated fuel generated by the evaporation of the fuel in the fuel tank31is introduced into the canister1through the evaporated fuel introducing port11by an increase in internal pressure of the fuel tank31. Then, the fuel components are adsorbed by the activated carbon of the first chamber21and the activated carbon of the second chamber22. The gas from which the fuel components have been mostly removed is released to the atmosphere through the atmosphere release port13.

When the first adsorbent51continuously adsorbs the evaporated fuel gas, and a fuel component concentration in the first adsorbent51increases to become a certain value or more, the evaporated fuel gas advances into the communicating portion T. Further, when the fuel component concentration in the communicating portion T increases to become a certain value or more, the second adsorbent61in the second chamber22adsorbs the fuel component from the side, far from the atmosphere release port13, of the second adsorbent61. When the fuel component concentration in the end portion, close to the atmosphere release port13, of the second adsorbent61increases to become a certain value or more, there is a possibility that the fuel components are released to the atmosphere through the atmosphere release port13. It should be noted that when the operation of the engine30is performed, and the purge is performed, the fuel components are gradually desorbed from the side, close to the atmosphere release port13, of the second adsorbent61.

Specifically, for example, when the purge valve36is opened by the ECU (not shown) or a pressure difference during the operation of the engine30, air in the atmosphere is introduced by intake negative pressure of the engine30into the second chamber22and the first chamber21in the canister1through the atmosphere release port13. At this time, the evaporated fuel is desorbed (purged) from the first adsorbent51of the first chamber21and the second adsorbent61of the second chamber22and supplied to the intake passage34of the engine30through the purge port12together with air.

In this case, in the present embodiment, the flow dividing plate62including the plurality of communicating holes62ais provided at a side of the second adsorbent61of the second chamber22, the side being close to the purge port12. The plurality of communicating holes62aare formed such that when the canister1is mounted on the vehicle, the area of the communicating holes per unit area on the surface of the flow dividing plate62is larger at the lower side of the flow dividing plate62than at the upper side of the flow dividing plate62. Therefore, ventilation resistance is relatively lower at the lower side of the second chamber22than at the upper side of the second chamber22. On this account, the evaporated fuel adsorbed by the second adsorbent61accommodated in the second chamber22is more easily desorbed at the lower side during the purge, and the amount of evaporated fuel remaining is smaller at the lower side. To be specific, as shown inFIG. 8, the fuel component concentration in the second adsorbent61is lower at the lower side by the purge.

With this, even when the fuel components adsorbed by the upper side of the second adsorbent61move to the lower side by gravity during the stop of the engine30, the lower side of the second adsorbent61has an enough adsorption capacity, so that the fuel components moving toward the lower side can be adsorbed by the lower side of the second adsorbent61. Therefore, as compared to conventional cases, it is possible to delay the start of the advancement of the fuel components in the second adsorbent61toward the atmosphere release port13. With this, a time from when the engine30stops until when the fuel components reach the end portion, close to the atmosphere release port13, of the second adsorbent61is increased. Therefore, the release of the fuel components to the atmosphere is suppressed.

It should be noted that in the present embodiment, the air layer (i.e., the filter plate63made of the non-woven fabric) is provided between the flow dividing plate62and the end portion, close to the atmosphere release port13, of the second adsorbent61. Therefore, the air flowing from the atmosphere release port13easily flows into the second adsorbent61through the end portion, close to the atmosphere release port13, of the second adsorbent61. On this account, even when the flow dividing plate62is provided, the deterioration of the use efficiency of the second adsorbent61can be suppressed. If the air layer (i.e., the filter plate63made of the non-woven fabric) is not provided between the flow dividing plate62and the end portion, close to the atmosphere release port13, of the second adsorbent61, the air flowing from the atmosphere release port13does not adequately flow into the second adsorbent61contacting portions other than the communicating holes62aof the flow dividing plate62. As a result, there is a possibility that the use efficiency of the second adsorbent61deteriorates.

The canister1of Embodiment 2 of the present invention will be explained. In Embodiment 2, the same drawings as Embodiment 1 are used. In Embodiment 2, the second adsorbent61is configured such that the evaporated fuel adsorption ability is higher at the portion close to the atmosphere release port13in the extending direction of the passage than at the portion far from the atmosphere release port13in the extending direction of the passage. If the adsorption ability of the entire second adsorbent61is increased evenly, the amount of fuel components remaining at the portion, far from the atmosphere release port13, of the second adsorbent at the time of the termination of the purge becomes large, and the time from when the engine stops until when the fuel components reach the end portion close to the atmosphere release port13is decreased. Therefore, the adsorption ability at the potion, far from the atmosphere release port13, of the second adsorbent61is set to be lower than the adsorption ability at the potion, close to the atmosphere release port13, of the second adsorbent61.

The evaporated fuel adsorption ability is generally represented by butane working capacity (BWC). In the present embodiment, the second adsorbent61is configured such that the butane working capacity (BWC) becomes larger in value at the portion close to the atmosphere release port13in the extending direction of the passage than at the portion far from the atmosphere release port13in the extending direction of the passage.

It should be noted that an adsorbent having large BWC denotes activated carbon used as the adsorbent and having high pore density per unit volume. For example, when forming the second adsorbent61, pellets having larger particle diameters than pellets laid at the portion close to the atmosphere release port13may be laid at the portion far from the atmosphere release port13.

The portion, close to the atmosphere release port13, of the second adsorbent61needs to have high adsorption ability, and in addition, has to be able to surely perform desorption when carrying out the purge. Therefore, it is preferable to set the adsorption ability in consideration of balance with the desorption performance at the time of the purge.

According to this configuration, the advancement of the remaining fuel components toward the atmosphere release port13in the second adsorbent61by capillarity becomes slower as the remaining fuel components get close to the atmosphere release port13. Therefore, the time from when the engine30stops until when the fuel components reach the end portion, close to the atmosphere release port13, of the second adsorbent61can be further increased. Thus, the release of the fuel components to the atmosphere can be suppressed more satisfactorily.

The canister1of Embodiment 3 of the present invention will be explained.FIG. 9is a sectional view of the canister1of Embodiment 3 of the present invention.FIG. 10is a sectional view taken along line C-C ofFIG. 9. In the canister1of Embodiment 3, the second chamber22accommodates a plurality of second adsorbents61. In the second chamber22, the second adsorbents61and space portions S are alternately arranged in the extending direction of the passage.

Specifically, the second chamber22accommodates the flow dividing plate62, the filter plate63, the second adsorbent61, the filter plate63, the ventilation plate64, a space forming member66, the ventilation plate64, the filter plate63, the second adsorbent61, the filter plate63, the ventilation plate64, a space forming member66, the ventilation plate64, the filter plate63, the second adsorbent61, the filter plate63, and the ventilation plate64in this order from the side close to the bottom plate10xof the casing main body10A (i.e., the side close to the atmosphere release port13). A stopper16projecting toward an inner side of the second chamber22in the vicinity of the bottom plate10xof the casing main body10A is formed on the tubular wall of the casing main body10A and the first partition wall14, and a spring65is interposed between the ventilation plate64and the lid10B of the casing10. The spring65presses the ventilation plate64toward the stopper16. Therefore, regarding the flow dividing plate62, the filter plate63, the second adsorbent61, the filter plate63, the ventilation plate64, the space forming member66, the ventilation plate64, the filter plate63, the second adsorbent61, the filter plate63, the ventilation plate64, the space forming member66, the ventilation plate64, the filter plate63, the second adsorbent61, the filter plate63, and the ventilation plate64, adjacent members press against each other, so that any gap is not formed between the members. According to the above configuration, by inserting the above members into the second chamber22in the above order through an opening of the casing main body10A, this structure can be easily realized.

The ventilation plate64and the filter plate63may be the same as the ventilation plate64and the filter plate63of Embodiment 1.

The space forming member66is interposed between the two adjacent ventilation plates64and forms a space between these ventilation plates64. As with the ventilation plate64, the space forming member66is formed by, for example, resin. The space forming member66and the adjacent ventilation plate(s)64may be formed integrally or may be coupled to each other by an adhesive or the like.

The second adsorbent61adsorbs and desorbs the evaporated fuel generated in the fuel tank31. The second adsorbent61of Embodiment 2 is different in length in the tube axis direction from the second adsorbent61of Embodiment 1 but may be the same in composition as the second adsorbent61of Embodiment 1. For example, activated carbon capable of adsorbing and desorbing the evaporated fuel can be utilized as the second adsorbent61of Embodiment 2.

Other than the above, Embodiment 3 is the same in configuration as Embodiment 1.

According to Embodiment 3, the second chamber22accommodates the plurality of second adsorbents61, and the second adsorbents61and the space portions S are alternately arranged in the second chamber22in the extending direction of the passage. With this, the remaining fuel components in each second adsorbent61hardly advance to the adjacent second adsorbent61. To be specific, the remaining fuel components in the second adsorbent61hardly advance toward the atmosphere release port13. With this, the time from when the engine30stops until when the fuel components reach the end portion, close to the atmosphere release port13, of the second adsorbent61is further increased, and therefore, the release of the fuel components to the atmosphere is suppressed more satisfactorily.

Conclusion

The canister1of each of the embodiments includes the following configurations and features.

The canister1of each of Embodiments 1 to 3 is a canister1mounted on a vehicle and configured to adsorb and desorb evaporated fuel, wherein: a passage through which a fluid flows is formed in the canister1; a first end of the passage includes an evaporated fuel introducing port11through which the evaporated fuel from a fuel tank31is introduced into the canister1and a purge port12through which the canister1communicates with an intake passage34of an engine30; a second end of the passage includes an atmosphere release port13communicating with an atmosphere; a first chamber21and a second chamber22are provided at the passage in this order from the first end side, the first chamber21accommodating a first adsorbent51configured to adsorb and desorb the evaporated fuel, the second chamber22accommodating a second adsorbent61configured to adsorb and desorb the evaporated fuel; the passage is configured to extend substantially horizontally when the canister1is mounted on the vehicle; a flow dividing plate62including a plurality of communicating holes62ais provided at a side of the second adsorbent61in the second chamber22, the side being close to the atmosphere release port13; and when the canister1is mounted on the vehicle, an area of the communicating holes per unit area on a surface of the flow dividing plate62is larger at a lower side of the flow dividing plate62than at an upper side of the flow dividing plate62.

In each of Embodiments 1 to 3, the air layer (i.e., the filter plate63made of the non-woven fabric) is provided between the flow dividing plate62and an end portion of the second adsorbent61, the end portion being close to the atmosphere release port13.

In Embodiment 2, the second adsorbent61is configured such that an evaporated fuel adsorption ability is higher at a portion, close to the atmosphere release port13in an extending direction of the passage, of the second adsorbent61than at a portion, far from the atmosphere release port13in the extending direction of the passage, of the second adsorbent61.

Other Embodiments

In the above embodiments, the flow dividing plate62is provided only at the side, close to the atmosphere release port13, of the second adsorbent61in the second chamber22. However, in the present invention, the flow dividing plate62may also be provided at the side, far from the atmosphere release port13, of the second adsorbent61. In this case, for example, a flow dividing plate62equivalent to the flow dividing plate62of each embodiment may be provided instead of the ventilation plate64located at the side, far from the atmosphere release port13, of the second adsorbent61.

Or, the ventilation plate64of the space forming member66may be configured as the flow dividing plate62similar in configuration to the flow dividing plate62.

In the above embodiments, the shape of each communicating hole62aof the flow dividing plate62is a circular shape. However, the shape of each communicating hole62aof the flow dividing plate62does not have to be a circular shape and may be a triangular shape, a quadrangular shape, a pentagonal shape, an oval shape, or any other shape.

In the above embodiments, the air layer between the flow dividing plate62and the end portion, close to the atmosphere release port13, of the second adsorbent61is constituted by the filter plate63made of the non-woven fabric. However, the air layer may be constituted by a space.

In Embodiment 3, three sets each including the ventilation plate64, the second adsorbent61, and the ventilation plate64are provided. However, the number of such sets may be two or four or more.

INDUSTRIAL APPLICABILITY

The canister of the present invention may be widely utilized as a canister mounted on a vehicle, such as an automobile, and configured to adsorb and desorb evaporated fuel.

LIST OF REFERENCE CHARACTERS