JP7196024B2 - canister - Google Patents

Description

The technology disclosed in this specification relates to canisters.

An evaporative fuel treatment device for a vehicle such as an automobile has a canister filled with an adsorbent capable of adsorbing and desorbing evaporative fuel. As a result, the evaporated fuel generated within the fuel tank is adsorbed by the adsorbent within the canister. The vaporized fuel adsorbed by the adsorbent is desorbed toward the intake passage leading to the internal combustion engine when the vehicle is running, that is, when the internal combustion engine is in operation.

By the way, since the desorption of the adsorbed evaporated fuel is an endothermic reaction, the temperature in the adsorption chamber tends to decrease during the desorption. However, since the desorption performance of the adsorbent decreases as the temperature decreases, it is desirable to suppress the temperature change associated with the desorption in the adsorption chamber. Japanese Patent Laid-Open No. 2002-200002 discloses that a capsule of a heat storage material, which is formed by enclosing a substance having a melting point at a temperature that can be taken in a canister, is accommodated in an adsorption chamber. The latent heat released when the encapsulated material solidifies suppresses temperature changes in the adsorption chamber during the desorption of vaporized fuel.

JP 2009-287395 A

However, the technique of Patent Document 1 requires a great deal of cost in selecting a substance having a suitable melting point, the material and dimensions of a container enclosing the substance, and manufacturing the heat storage material capsule.

Therefore, the problem to be solved by the technology disclosed in the present specification was invented in view of the above-mentioned points, and the temperature at which the vaporized fuel is desorbed is reduced while suppressing the increase in cost. An object of the present invention is to provide a canister in which deterioration is suppressed.

In order to solve the above problems, the canister disclosed in this specification takes the following measures.

A first means comprises a casing having a tank port, a purge port, and an atmospheric port, and a purge flow path extending from the atmospheric port to the purge port inside the casing, and an adsorbent is formed in the casing. and a plurality of filled adsorption chambers, wherein a second adsorption chamber of the plurality of adsorption chambers is located closer to the purge port than the first adsorption chamber located closest to the atmosphere port. At least one of the subsequent adsorption chambers is provided with an occupancy member having an occupied portion that occupies the one adsorption chamber while being separated from the peripheral wall of the casing. A canister having a thermal conductivity less than that of the casing of the canister.

According to the first means, in at least one of the adsorption chambers subsequent to the second adsorption chamber into which low-temperature air tends to flow due to the desorption of vaporized fuel in the adsorption chamber located on the atmospheric port side, the temperature It is possible to suppress the deterioration of the desorption performance of the adsorbent due to the decrease of

The second means is the canister of the first means, wherein the occupying member is hollow.

According to the second means, the thermal conductivity of the occupied portion as a whole can be set low without using a special material.

A third means is a casing having a tank port, a purge port, and an atmospheric port, and a purge flow path extending from the atmospheric port to the purge port inside the casing, and an adsorbent is formed along the casing. and a plurality of filled adsorption chambers, wherein a second adsorption chamber of the plurality of adsorption chambers is located closer to the purge port than the first adsorption chamber located closest to the atmosphere port. A portion of the peripheral wall of the casing defining at least one of the subsequent adsorption chambers is a canister forming an inwardly concave shape of the one adsorption chamber.

According to the third means, the same effects as those of the first means can be obtained.

A fourth means is the canister according to any one of the first to third means, wherein the adsorption flow path extending from the tank port to the atmosphere port is formed along the purge flow path. At least part of the plurality of adsorption chambers is shared with the purge channel, and the area of the adsorption chamber filled with the adsorbent has a cross-sectional area orthogonal to the adsorption channel that is equal to the atmosphere. A canister that is shaped to decrease toward the port.

According to the fourth means, it is possible to effectively suppress the blow-by caused by the decrease in fuel vapor concentration.

The canister disclosed in the present specification can suppress temperature drop during desorption of fuel vapor while suppressing an increase in cost by employing the above-described means.

1 is a cross-sectional view of a canister according to a first embodiment; FIG. Figure 2 is a perspective view of one of the occupying members shown in Figure 1; 2 is a perspective view of the other occupying member shown in FIG. 1; FIG. FIG. 11 is a perspective view showing an adsorption chamber of a canister according to a second embodiment; It is an example of an occupation member arranged in a canister according to a modification of the first embodiment. It is another example of the occupying member arranged in the canister according to the modified example of the first embodiment. FIG. 11 is a perspective view showing an adsorption chamber of a canister according to a modified example of the second embodiment;

Hereinafter, embodiments of the canister according to the present disclosure will be described based on the drawings.

[First embodiment]
The configuration of the canister 1 according to the first embodiment will be described with reference to FIGS. 1 to 3. FIG. The canister 1 shown in FIG. 1 is mounted on a vehicle such as an automobile having an internal combustion engine (gasoline engine in this embodiment). For convenience, the vertical and horizontal directions of the canister 1 are defined with reference to FIG. Moreover, let the front-back direction of paper be the front-back direction. These directions do not necessarily match the directions when mounted on the vehicle. A right-handed orthogonal coordinate system is adopted as the coordinate system, and the horizontal direction corresponds to the X-axis, the front-rear direction corresponds to the Y-axis, and the vertical direction corresponds to the Z-axis.

As shown in FIG. 1, the canister 1 includes a casing 10 made of resin such as PA66 nylon resin. The casing 10 is composed of a cylindrical casing body 12 with a bottom opening and a casing lid 14 closing the bottom opening of the casing body 12 . The casing main body 12 is composed of a peripheral wall portion 12A and a top plate portion 12B that closes the upper end of the peripheral wall portion 12A. A top plate portion 12B of the casing main body 12 is formed with a tank port 16 communicating with a fuel tank, a purge port 18 communicating with an intake passage of the internal combustion engine, and an atmosphere port 20 communicating with the atmosphere. A partition wall 22 extends downward from the lower surface of the top plate portion 12B of the casing main body 12, dividing the interior of the casing 10 into two spaces, left and right. Adsorption chamber 24 is defined in the left space, and adsorption chambers 26 and 28 are defined in the right space. The adsorption chamber 28 corresponds to the first adsorption chamber in this specification, and the adsorption chamber 26 corresponds to the second adsorption chamber in this specification. The peripheral wall portion 12A corresponds to the peripheral wall in this specification.

(Structure of Adsorption Chamber and Communication Path)
The configuration of the adsorption chambers 24, 26 and 28 and the communication passage 64 will be described. The adsorption chamber 24 is filled with an adsorbent 30 made of activated carbon particles. Sheet-like filters 32 and 34 having air permeability are interposed between the adsorbent 30 and the top plate portion 12B. Filters 32 and 34 are made of non-woven fabric, for example. The adsorbent 30 in the adsorption chamber 24 is supported from below by a breathable urethane sheet 36 . Below the urethane sheet 36, a resin occupation member 42 having a base portion 38 and a hollow conical occupation portion 40 formed on the base portion 38 is arranged. The occupied portion 40 is buried in the adsorbent 30 . The urethane sheet 36 is formed with a hole through which the occupied portion 40 protrudes upward. The structure of the occupying member 42 will be described later with reference to FIG. A coil spring 44 is interposed in a compressed state between the base portion 38 of the occupying member 42 and the top plate portion of the casing lid 14 to urge the base portion 38 upward. Inside the adsorption chamber 24, a partial wall 46 extends downward on the lower surface of the top plate portion 12B of the casing body 12, dividing the upper portion of the adsorption chamber 24 into left and right compartments.

The adsorption chamber 26 is also filled with an adsorbent 30 . The adsorbent 30 in the adsorption chamber 26 is supported from below by a breathable urethane sheet 48 . A perforated plate 50 made of resin is arranged below the urethane sheet 48 . A coil spring 52 is arranged in a compressed state between the perforated plate 50 and the top plate portion of the casing lid 14 to urge the perforated plate 50 upward. In the upper part of the adsorption chamber 26, a resin-made occupying member 58 having a base portion 54 and a hollow truncated cone-shaped occupying portion 56 formed on the upper surface of the base portion 54 is positioned with the base portion 54 positioned upward. It is arranged in The occupied portion 56 of the occupied member 58 is buried in the adsorbent 30 . The structure of the occupying member 58 will be described later with reference to FIG.

The adsorption chamber 28 is also filled with an adsorbent 30 . A sheet-like filter 60 having air permeability is interposed between the adsorbent 30 and the top plate portion 12B. Filter 60 consists of nonwoven fabrics, for example. Between the adsorption chamber 26 and the adsorption chamber 28, a resin-made partition member 62 having air permeability is interposed. The partition member 62 divides the space on the right side of the partition wall 22 in the casing 10 into the adsorption chambers 26 and 28 . That is, the adsorbent 30 in the adsorption chamber 26 and the adsorbent 30 in the adsorption chamber 28 are separated from each other. A communication passage 64 is defined by the lower portion of the peripheral wall portion 12A of the casing main body 12, the top plate portion of the casing lid 14, the base portion 38 of the occupying member 42, and the perforated plate 50. As shown in FIG. The adsorption chamber 24 and the adsorption chamber 26 communicate with each other through a communication passage 64 . The adsorption chamber 24 , the communication passage 64 , the adsorption chamber 26 and the adsorption chamber 28 form a substantially U-shaped fluid passage 66 .

(Occupying member)
2 shows a perspective view of the occupying member 42. The base portion 38 of the occupying member 42 has a rectangular flat plate shape having substantially the same shape as the cross section of the adsorption chamber 24. As shown in FIG. A lattice is formed in a portion of the base portion 38 excluding the base end of the occupied portion 40 and its periphery, and the occupied member 42 has air permeability due to the lattice. The occupied portion 40 has a conical shape and is hollow as indicated by the dotted line.

FIG. 3 shows a perspective view of the occupying member 58 in the vertical direction opposite to the orientation shown in FIG. The base portion 54 of the occupying member 58 has a rectangular flat plate shape having substantially the same shape as the cross section of the adsorption chamber 26 . A lattice is formed in a portion of the base portion 54 excluding the proximal end of the occupied portion 56 and its surroundings, and the occupied member 58 has air permeability due to the lattice. The occupied portion 56 has a truncated cone shape and is hollow as indicated by the dotted line. In the first embodiment, both the occupying member 42 and the occupying member 58 may be made of the same resin as that forming the casing 10 .

(Canister assembly)
The canister 1 is assembled by the following steps. First, the orientation of the casing body 12 is maintained so that each port faces downward, that is, the orientation shown in FIG. 1 is reversed vertically. The filters 32, 34 and 60 are placed on the top plate portion 12B, respectively. Then, the adsorbent 30 is filled on the filters 32 , 34 and 60 . A urethane sheet 36 is placed on the adsorbent 30 filled in the space on the side where the tank port 16 and the purge port 18 are formed in the top plate portion 12B of the space partitioned by the partition wall 22 of the casing body 12. Then, while inserting the occupied portion 40 into the hole of the urethane sheet 36, the occupied member 42 is placed. Further, among the spaces partitioned by the partition wall 22 of the casing body 12, the partition member 62 is placed on the adsorbent 30 filled in the space on the side where the air port 20 is formed in the top plate portion 12B, The occupying member 58 is placed on the partition member 62 so that the base portion 54 is on the partition member 62 side. The adsorbent 30 is filled again, and the urethane sheet 48 and the perforated plate 50 are placed on the adsorbent 30 in this order. A coil spring 44 is fixed to the base portion 38 of the occupying member 42 , a coil spring 52 is fixed to the perforated plate 50 , and the opening of the casing main body 12 is covered with the casing lid 14 . After that, the casing main body 12 and the casing lid 14 are joined by welding.

(Flow of evaporated fuel)
The flow of evaporated fuel within the canister 1 will be described with reference to FIG. In a vehicle equipped with the canister 1, for example, when the vehicle is parked, vaporized fuel is generated in the fuel tank. The generated vaporized fuel passes through a vapor passage connecting the fuel tank and the tank port 16 of the canister 1 and flows into the adsorption chamber 24 via the tank port 16 . The vaporized fuel that has flowed into the adsorption chamber 24 is adsorbed by the adsorbent 30 in each adsorption chamber while flowing through the fluid passage 66 in the order of the adsorption chamber 24 , the communication passage 64 , the adsorption chamber 26 and the adsorption chamber 28 . Then, air that does not contain fuel vapor or that contains a very small amount of fuel vapor is released to the atmosphere through the atmosphere port 20 . Incidentally, the tank port 16, the fluid passage 66 and the atmosphere port 20 correspond to the adsorption channel in this specification.

On the other hand, when the vehicle is running, that is, when the internal combustion engine is in operation, the interior of the casing 10 is sucked through the purge port 18 by a purge pump disposed in the purge passage communicating the purge port 18 and the intake passage. Then, air flows into the casing 10 from the atmosphere port 20, flows through the fluid passage 66 through the adsorption chamber 28, the adsorption chamber 26, the communication passage 64, and the adsorption chamber 24 in this order, and then flows out from the purge port 18 to the purge passage. . At this time, the vaporized fuel adsorbed on the adsorbent 30 filled in each adsorption chamber is desorbed from the adsorbent 30 and flows through the fluid passage 66 toward the purge port 18 together with air. The atmosphere port 20, the fluid passage 66 and the purge port 18 correspond to the purge channel in this specification.

(Advantages of the first embodiment)
In general, the desorption of adsorbed evaporated fuel is an endothermic reaction. When the vaporized fuel is desorbed, the fluid flows through the fluid passage 66 in the order of the adsorption chamber 28, the adsorption chamber 26, the communication passage 64, and the adsorption chamber 24, as described above. At that time, the temperature of the air that has flowed in from the atmosphere port 20 gradually decreases as it flows through the fluid passage 66 toward the purge port 18 . That is, when the vaporized fuel is desorbed, the temperatures in the adsorption chambers 26 and 24 become lower than the temperature in the adsorption chamber 28, so the adsorbent 30 filled in these adsorption chambers desorbs. Releasing performance is also reduced relative to the adsorbent 30 within the adsorption chamber 28 .

In the first embodiment, inside the adsorption chamber 26 and the adsorption chamber 24 located closer to the purge port 18 than the adsorption chamber 28 located closest to the atmosphere port 20, an occupation member 58 having an occupation portion 56 and an occupation member 58 are provided. An occupation member 42 having a portion 40 is provided. The occupied portion 40 is spaced apart from the peripheral wall portion 12A, and similarly, the occupied portion 56 is also spaced apart from the peripheral wall portion 12A. The occupied portion 40 and the occupied portion 56 are hollow. As a result, the thermal conductivity of the occupied portion 40 and the occupied portion 56 is lower than that of the casing 10 . Note that the thermal conductivity of the occupied portion 40 refers to the average value of the thermal conductivity of each portion of the occupied portion 40 . That is, the sum of the product of the volume of the resin portion of the occupied portion 40 and the thermal conductivity of the resin and the product of the volume of the hollow portion and the thermal conductivity of the air is calculated as the sum of the volume of the resin portion and the volume of the hollow portion. refers to the value obtained by dividing by The thermal conductivity of the occupied portion 56 is similarly obtained.

Heat conduction occurs mainly through the peripheral wall portion 12A between the air in the adsorption chamber and between the adsorbent 30 and the outside air. Therefore, when air having a lower temperature than the outside air flows into the adsorption chamber, the temperature of the adsorbent 30 in the region near the peripheral wall portion 12A is relatively suppressed from decreasing due to the inflowing air. The temperature of the adsorbent 30 in a region away from .theta. However, in this embodiment, in the adsorption chamber 24 and the adsorption chamber 26, the occupying member 42 and the occupying member 58 are arranged in regions separated from the peripheral wall portion 12A of the casing body 12, respectively. As a result, in the adsorption chambers 24 and 26, at least part of the region separated from the peripheral wall portion 12A of the casing body 12 is not filled with the adsorbent 30. As shown in FIG. That is, the adsorption chambers 24 and 26 are mainly filled with the adsorbent 30 in regions where heat conduction with the outside air is relatively likely to occur. Furthermore, since the occupying member 42 and the occupying portion 56 are hollow and have a lower thermal conductivity than the casing 10, the temperature does not easily drop. From the above, in the adsorption chambers (adsorption chambers 24 and 26 in the present embodiment) into which low-temperature air tends to flow, deterioration in desorption performance of the adsorbent 30 due to a decrease in temperature can be suppressed. can be done.

Also, the occupation portion 40 has a conical shape, and the cross-sectional area of the occupation portion 40 perpendicular to the fluid passage 66 increases above the fluid passage 66 toward the atmosphere port 20 . Similarly, the occupying portion 56 has a frusto-conical shape, and the cross-sectional area of the occupying portion 56 perpendicular to the fluid passageway 66 increases above the fluid passageway 66 toward the atmospheric port 20 . In other words, the cross-sectional area of the adsorbent-filled region of the adsorption chamber, perpendicular to the flow direction of the vaporized fuel, decreases toward the atmosphere port 20 .

The evaporated fuel flowing from the tank port 16 is adsorbed by the adsorbent 30 filled in each adsorption chamber while flowing through the fluid passage 66 toward the atmosphere port 20. Therefore, the concentration of the evaporated fuel not adsorbed is reduced to that of the atmosphere. It descends towards port 20. In general, the lower the concentration of evaporated fuel, the lower the percentage of evaporated fuel adsorbed by the adsorbent, so that so-called blow-through is more likely to occur. On the other hand, in the present embodiment, the shape of each occupied portion (occupied portion 40, occupied portion 56) is formed as described above. Therefore, in the adsorption chamber (adsorption chamber 24, adsorption chamber 26) in which the occupied portion is arranged, the length in the flow direction of the vaporized fuel in the adsorption chamber is set to L, and the length of the region filled with the adsorbent in the adsorption chamber is evaporating. The L/D value, where D is the diameter of a circle having an area equivalent to the cross-sectional area perpendicular to the fuel flow direction, gradually increases toward the atmosphere port 20 . In general, blow-through is suppressed as the L/D value increases. As described above, in the adsorption chamber in which the occupied portion is arranged, it is possible to effectively suppress blow-by due to a decrease in the fuel vapor concentration.

[Second embodiment]
A second embodiment will be described with reference to FIG. In addition, in the second embodiment, description of parts having the same configuration as in the first embodiment is omitted. Further, constituent elements that correspond to but have different shapes from those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and different points will be described.

In the first embodiment, the occupying member 42 and the occupying member 58 are arranged in the adsorption chamber 24 and the adsorption chamber 26, respectively. In the second embodiment, instead of arranging an occupying member in the adsorption chamber, a part of the peripheral wall portion 12A of the casing body 12 defining the adsorption chamber is made concave toward the inside of the adsorption chamber. did. In the adsorption chamber 26 shown in FIG. 4, of the peripheral wall portion 12A of the casing body 12, a portion corresponding to the wall surface on the right side of the adsorption chamber 26 forms a concave shape extending inwardly of the adsorption chamber 26. As shown in FIG.

(Advantages of Second Embodiment)
In the second embodiment, a portion of the peripheral wall portion 12A of the casing body 12 that defines the adsorption chamber 26 positioned closer to the purge port 18 than the adsorption chamber 28 positioned closest to the atmosphere port 20 on the fluid passage 66. forms a concave shape directed inward of the adsorption chamber 26 . That is, in the second embodiment, in the adsorption chamber 26, the region where the distance from the peripheral wall portion 12A of the casing main body 12 is large is removed. Therefore, most of the adsorbent 30 in the adsorption chamber 26 is more likely to conduct heat with the atmosphere via the peripheral wall portion 12A. decline can be suppressed. From the above, in the second embodiment as well, in the adsorption chamber (adsorption chamber 26 in this embodiment) into which low-temperature air tends to flow, the desorption performance of the adsorbent 30 is lowered due to the temperature drop. can be suppressed.

[Modification]
The canister disclosed herein is not limited to the embodiments described above and can be modified in other forms. In the first embodiment, the shapes of the occupying members provided in the adsorption chambers 24 and 26 are not limited to the shapes of the occupying members 42 and 58, respectively.
The adsorption chamber 24 may be provided with an occupation member having a truncated conical occupation portion, and the adsorption chamber 26 may be provided with an occupation member having a conical occupation portion. At least one of the adsorption chambers 24 and 26 may be provided with an occupation member having a hollow columnar occupation portion as shown in FIG. Alternatively, as shown in FIG. 6, an occupying member having a plurality of (three in FIG. 6) hollow cylinders may be provided as the occupying portion. As long as the occupying member has an occupying portion, it does not necessarily have to have a base portion. In that case, it is desirable to provide the occupied portion with arbitrary positioning means for positioning within the adsorption chamber. The occupied portion does not have to be hollow. In that case, it is preferable to form the occupied portion from a material having a lower thermal conductivity than the resin forming the casing 10 .

The occupying member may be arranged in only one of the adsorption chambers 24 and 26 . Further, when the canister has four or more adsorption chambers, the occupying member is at least one of the adsorption chambers after the adsorption chamber positioned closer to the purge port than the adsorption chamber positioned closest to the atmosphere port on the fluid passage. It is sufficient if they are arranged in one adsorption chamber.

In the second embodiment, for the adsorption chamber 24 instead of the adsorption chamber 26, or for both the adsorption chamber 24 and the adsorption chamber 26, a part of the peripheral wall portion 12A of the casing body 12 defining the adsorption chamber is It may have a concave shape facing the inside of the room. Also, the shape of the adsorption chamber is not limited to the shape shown in FIG. For example, as shown in FIG. 7, the cross-sectional area of the adsorption chamber (here, the adsorption chamber 26 is illustrated as an example) may be formed so as to decrease on the fluid passage toward the atmospheric port. As a result, the L/D can be increased toward the atmosphere port, and blow-through can be effectively suppressed.

1 canister 10 casing 12A peripheral wall (peripheral wall of casing)
16 tank port 18 purge port 20 atmosphere port 24 adsorption chamber 26 adsorption chamber (second adsorption chamber)
28 adsorption chamber (first adsorption chamber)
30 adsorbents 40, 56 occupied parts 42, 58 occupied members

Claims (3)

a casing having a tank port, a purge port, and an atmospheric port;
a plurality of adsorption chambers formed inside the casing along a purge flow path extending from the atmosphere port to the purge port and filled with an adsorbent,
Air passing through at least the first adsorption chamber located closer to the purge port than the first adsorption chamber, of the plurality of adsorption chambers, which is located closest to the atmospheric port and into which air directly flows from the atmospheric port . an occupying member having an occupying portion that occupies the one adsorption chamber while being separated from the peripheral wall of the casing is disposed in at least one of the adsorption chambers after the second adsorption chamber into which the second adsorption chamber flows ;
The occupying member is not arranged in the first adsorption chamber,
The canister, wherein the occupied portion of the occupied member has a lower thermal conductivity than the casing of the canister. 2. The canister according to claim 1, wherein said occupying member is hollow. 3. The canister according to claim 1, wherein the adsorption flow path extending from the tank port to the atmospheric port is at least one of the plurality of adsorption chambers formed along the purge flow path. part of which is shared with the purge flow path,
The canister, wherein the region filled with the adsorbent of the one adsorption chamber is formed such that the area of the cross section perpendicular to the adsorption channel decreases toward the atmosphere port.

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