JP2021004594A - Canister - Google Patents

Abstract

To provide a canister capable of reducing temperature change upon adsorbing or desorbing evaporated fuel while suppressing cost increase.SOLUTION: Inside an adsorption chamber 26 and an adsorption chamber 24 located on a purge port 18 side of an adsorption chamber 28 located closest to an atmospheric port 20, an occupied member 58 having an occupied part 56 and an occupied member 42 having an occupied part 40 are respectively arranged. The occupied part 40 and the occupied part 56 are hollow.SELECTED DRAWING: Figure 1

Description

The techniques disclosed herein relate to canisters.

An evaporative fuel processing device for a vehicle such as an automobile has a canister filled with an adsorbent capable of adsorbing and desorbing the evaporated fuel. As a result, the evaporated fuel generated in the fuel tank is adsorbed by the adsorbent in the canister. Then, the evaporated fuel adsorbed on 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 operating.

By the way, since the desorption of the adsorbed evaporated fuel is an endothermic reaction, the temperature in the adsorption chamber at the time of desorption tends to decrease. However, since the desorption performance of the adsorbent decreases as the temperature decreases, it is desirable to suppress the temperature change due to desorption in the adsorption chamber. Patent Document 1 discloses that a capsule of a heat storage material formed by encapsulating a substance having a melting point at a temperature that can be taken in a canister is housed in an adsorption chamber. The latent heat released when the substance encapsulated in the capsule solidifies suppresses the temperature change of the adsorption chamber during desorption of the evaporated fuel.

JP-A-2009-287395

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

Therefore, the problem to be solved by the technique disclosed in the present specification is devised in view of the above-mentioned points, and the temperature at which the evaporated fuel is desorbed while suppressing the increase in cost. It is to provide a canister that suppresses the decrease.

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

The first means is a casing in which a tank port, a purge port, and an atmospheric port are formed, and an adsorbent formed inside the casing along a purge flow path extending from the atmospheric port to the purge port. A canister including a plurality of filled adsorption chambers, the second adsorption chamber located closer to the purge port than the first adsorption chamber located closest to the atmosphere port among the plurality of adsorption chambers. In at least one suction chamber of the subsequent suction chambers, an occupying member having an occupying portion occupying the one suction chamber while being separated from the peripheral wall of the casing is disposed, and the occupying portion of the occupying member. The thermal conductivity of the canister is smaller than the thermal conductivity of the casing of the canister.

According to the first means, the temperature in at least one adsorption chamber after the second adsorption chamber where low temperature air tends to flow in due to desorption of evaporated fuel in the adsorption chamber located on the atmospheric port side. It is possible to suppress a decrease in the desorption performance of the adsorbent due to a decrease in

The second means is a canister of the first means, the occupied member being formed in a hollow shape.

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

The third means is a casing in which the tank port, the purge port, and the atmospheric port are formed, and the adsorbent is formed inside the casing along the purge flow path extending from the atmospheric port to the purge port. A canister including a plurality of filled adsorption chambers, the second adsorption chamber located closer to the purge port than the first adsorption chamber located closest to the atmospheric port among the plurality of adsorption chambers. A part of the peripheral wall of the casing, which defines at least one suction chamber of the subsequent suction chambers, is a canister having a concave shape toward the inside of the one suction chamber.

According to the third means, the same effect as that of the first means can be obtained.

The fourth means is the canister of any of the first to third means, and the adsorption flow path extending from the tank port to the atmosphere port is formed along the purge flow path. At least a part of the plurality of adsorption chambers is shared with the purge flow path, and the area of the cross section orthogonal to the adsorption flow path in the region filled with the adsorption material in the one adsorption flow path is the atmosphere. A canister that is formed to diminish towards the port.

According to the fourth means, it is possible to effectively suppress a stairwell due to a decrease in the concentration of evaporated fuel.

By taking the above-mentioned measures, the canister disclosed in the present specification can suppress a temperature drop when desorbing the evaporated fuel while suppressing an increase in cost.

It is sectional drawing of the canister which concerns on 1st Embodiment. It is a perspective view of one occupied member shown in FIG. It is a perspective view of the other occupied member shown in FIG. It is a perspective view which shows the suction chamber of the canister which concerns on 2nd Embodiment. This is an example of an occupied member arranged in the canister according to the modified example of the first embodiment. This is another example of the occupied member arranged in the canister according to the modified example of the first embodiment. It is a perspective view which shows the suction chamber of the canister which concerns on the modification of 2nd Embodiment.

Hereinafter, embodiments of the canister according to the present disclosure will be described with reference to 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. The canister 1 shown in FIG. 1 is mounted on a vehicle having an internal combustion engine (gasoline engine in this embodiment) such as an automobile. For convenience, the vertical and horizontal directions of the canister 1 are determined with reference to FIG. In addition, the front-back direction of the paper surface is the front-back direction. These directions do not always match the directions when mounted on the vehicle. Right-handed Cartesian coordinates are adopted as the coordinate system, and the left-right direction is associated with the X-axis, the front-back direction is associated with the Y-axis, and the vertical direction is associated with the Z-axis.

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

(Structure of adsorption chamber and communication passage)
The configurations of the suction chambers 24, 26 and 28 and the communication passage 64 described above will be described. The adsorption chamber 24 is filled with an adsorbent 30 made of activated carbon particles. Sheet-shaped filters 32 and 34 having air permeability are interposed between the adsorbent 30 and the top plate portion 12B. The filters 32 and 34 are made of, for example, non-woven fabric. The adsorbent 30 in the adsorption chamber 24 is supported by a urethane sheet 36 having breathability from below. Below the urethane sheet 36, a resin occupying member 42 having a base portion 38 and a hollow conical occupying portion 40 formed on the base portion 38 is disposed. 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 projects upward. The structure of the occupying member 42 will be described later with reference to FIG. A coil spring 44 is interposed between the base portion 38 of the occupying member 42 and the top plate portion of the casing lid 14 in a compressed state, and urges the base portion 38 upward. Further, inside the suction chamber 24, a partial wall 46 extends downward on the lower surface of the top plate portion 12B of the casing main body 12, and the upper portion of the suction chamber 24 is divided into left and right branch chambers.

The adsorption chamber 26 is also filled with the adsorbent 30. The adsorbent 30 in the adsorption chamber 26 is supported by a breathable urethane sheet 48 from below. A resin perforated plate 50 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, and urges the perforated plate 50 upward. In the upper part of the suction chamber 26, a resin 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 in a state where the base portion 54 is positioned above. It is arranged by. The occupied portion 56 of the occupied member 58 is buried in the adsorbent 30. The structure of the occupied member 58 will be described later with reference to FIG.

The adsorption chamber 28 is also filled with the adsorbent 30. A breathable sheet-shaped filter 60 is interposed between the adsorbent 30 and the top plate portion 12B. The filter 60 is made of, for example, a non-woven fabric. A partition member 62 made of a breathable resin is interposed between the suction chamber 26 and the suction chamber 28. The partition member 62 divides the space on the right side of the partition wall 22 in the casing 10 into the suction 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. Further, the 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. The suction chamber 24 and the suction chamber 26 communicate with each other via a communication passage 64. The suction chamber 24, the communication passage 64, the suction chamber 26, and the suction chamber 28 form a substantially U-shaped fluid passage 66.

(Occupied member)
FIG. 2 shows a perspective view of the occupied member 42, and the base portion 38 of the occupied member 42 has a rectangular flat plate shape having substantially the same shape as the cross section of the suction chamber 24. A grid is formed on the base portion 38 except for the base end of the occupied portion 40 and its periphery, and the occupied member 42 has air permeability due to the grid. The occupied portion 40 has a conical shape and is formed to be hollow as shown by a dotted line.

FIG. 3 shows a perspective view of the occupied member 58 in a direction opposite to that shown in FIG. 1 in the vertical direction. The base portion 54 of the occupied member 58 has a rectangular flat plate shape having substantially the same shape as the cross section of the suction chamber 26. A grid is formed on the base portion 54 except for the base end of the occupied portion 56 and its periphery, and the occupied member 58 has air permeability due to the grid. The occupied portion 56 has a truncated cone shape and is formed to be hollow as shown by a dotted line. In the first embodiment, the occupied member 42 and the occupied member 58 may both be formed of the same resin as the resin forming the casing 10.

(Assembly of canister)
The canister 1 is assembled by the following steps. First, the orientation of the casing body 12 is maintained so that each port comes down, that is, the orientation is reversed in the vertical direction from the orientation shown in FIG. 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. Of the space partitioned by the partition wall 22 of the casing main body 12, the 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 on the top plate portion 12B. The occupied member 42 is placed while inserting the occupied portion 40 into the hole of the urethane sheet 36. Further, among the spaces partitioned by the partition wall 22 of the casing main body 12, the partition member 62 is placed on the adsorbent 30 filled in the space on the side where the atmospheric port 20 is formed in the top plate portion 12B. The occupied member 58 is placed on the partition member 62 so that the base portion 54 is on the side of the partition member 62. 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. The coil spring 44 is fixed to the base portion 38 of the occupying member 42, the coil spring 52 is fixed to the perforated plate 50, and the opening of the casing body 12 is covered with the casing lid 14. After that, the casing body 12 and the casing lid 14 are joined by welding.

(Flow of evaporated fuel)
The flow of evaporated fuel in the canister 1 will be described with reference to FIG. In a vehicle equipped with the canister 1, evaporative fuel is generated in the fuel tank, for example, when parking. The generated evaporated fuel passes through the vapor passage that connects the fuel tank and the tank port 16 of the canister 1, and flows into the adsorption chamber 24 through the tank port 16. The evaporated fuel that has flowed into the adsorption chamber 24 flows 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, and is adsorbed by the adsorbent 30 in each adsorption chamber. Then, air containing no evaporative fuel or containing a very small amount of fuel is discharged from the atmospheric port 20 to the atmosphere. The tank port 16, the fluid passage 66, and the atmosphere port 20 correspond to the adsorption passages in the present specification.

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

(Advantages of First Embodiment)
In general, the desorption of adsorbed evaporated fuel is an endothermic reaction. Then, at the time of desorption of the evaporated fuel, as described above, the fluid passage 66 flows in the suction chamber 28, the suction chamber 26, the communication passage 64, and the suction chamber 24 in this order. At that time, the temperature of the air flowing in from the atmospheric port 20 gradually decreases as it flows through the fluid passage 66 toward the purge port 18. That is, when the evaporated fuel is desorbed, the temperatures in the adsorption chamber 26 and the adsorption chamber 24 are lower than the temperature in the adsorption chamber 28, so that the adsorbent 30 filled in these adsorption chambers is desorbed. The release performance is also lower than that of the adsorbent 30 in the adsorption chamber 28.

In the first embodiment, the suction chamber 26 located closer to the purge port 18 than the suction chamber 28 located closest to the atmospheric port 20 and the inside of the suction chamber 24 are occupied by an occupied member 58 having an occupied portion 56, respectively. An occupying member 42 having a portion 40 is arranged. The occupied portion 40 is arranged separately from the peripheral wall portion 12A, and similarly, the occupied portion 56 is also arranged separated 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. 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 air is 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 also obtained in the same manner.

Heat conduction occurs between the air in the adsorption chamber or the adsorbent 30 and the outside air mainly through the peripheral wall portion 12A. Therefore, when air lower than the outside air flows into the adsorption chamber, the temperature drop of the adsorbent 30 in the region near the peripheral wall portion 12A is relatively suppressed due to the inflowing air, but the peripheral wall portion 12A of the casing main body 12 The temperature of the adsorbent 30 in the region separated from the adsorbent 30 is significantly lowered. However, in the present embodiment, in the suction chamber 24 and the suction chamber 26, the occupying member 42 and the occupying member 58 are arranged in the regions separated from the peripheral wall portion 12A of the casing main body 12, respectively. As a result, in the suction chamber 24 and the suction chamber 26, at least a part of the region separated from the peripheral wall portion 12A of the casing main body 12 is not filled with the adsorbent 30. That is, in the adsorption chamber 24 and the adsorption chamber 26, the adsorbent 30 is mainly filled in a region where heat conduction is relatively likely to occur with the outside air. Further, since the occupied member 42 and the occupied portion 56 are formed to be hollow and have a lower thermal conductivity than the casing 10, the temperature is unlikely to decrease. From the above, in the adsorption chamber (in this embodiment, the adsorption chamber 24 and the adsorption chamber 26) where low-temperature air tends to flow in, it is possible to suppress the deterioration of the desorption performance of the adsorbent 30 due to the decrease in temperature. Can be done.

Further, the occupied portion 40 has a conical shape, and the area of the occupied portion 40 in the cross section orthogonal to the fluid passage 66 increases toward the atmosphere port 20 on the fluid passage 66. Similarly, the occupied portion 56 has a truncated cone shape, and the area of the occupied portion 56 in the cross section orthogonal to the fluid passage 66 increases toward the atmosphere port 20 on the fluid passage 66. In other words, the cross-sectional area of the region filled with the adsorbent in the adsorption chamber, which is orthogonal to the flow direction of the evaporated fuel, decreases toward the atmospheric port 20.

Since the evaporated fuel flowing in 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, the concentration of the evaporated fuel not adsorbed is the atmosphere. It decreases toward port 20. In general, as the concentration of the evaporated fuel decreases, the proportion of the evaporated fuel adsorbed on the adsorbent decreases, so that so-called blow-by is 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, the length of the adsorption chamber (adsorption chamber 24, adsorption chamber 26) in which the occupied portion is arranged in the flow direction of the evaporated fuel in the adsorption chamber is set to L, and the region of the adsorption chamber filled with the adsorbent is evaporated. The L / D value when the diameter of the circle having the same area as the cross-sectional area orthogonal to the fuel flow direction is D is gradually increased toward the atmospheric port 20. Generally, the larger the L / D value, the more the stairwell is suppressed. From the above, in the adsorption chamber in which the occupied portion is arranged, it is possible to effectively suppress the blow-by due to the decrease in the concentration of evaporated fuel.

[Second Embodiment]
A second embodiment will be described with reference to FIG. In the second embodiment, the description of the portion having the same configuration as that of the first embodiment will be omitted. Further, the components corresponding to the first embodiment but having different shapes are also designated by the same reference numerals as those of the first embodiment, and the differences will be described.

In the first embodiment, the occupied member 42 and the occupied member 58 are arranged in the suction chamber 24 and the suction chamber 26, respectively. In the second embodiment, instead of disposing the occupied member in the suction chamber, a part of the peripheral wall portion 12A of the casing main body 12 that defines the suction chamber has a concave shape toward the inside of the suction chamber. did. In the suction chamber 26 shown in FIG. 4, a portion of the peripheral wall portion 12A of the casing main body 12 corresponding to the wall surface on the right side of the suction chamber 26 has a concave shape toward the inside of the suction chamber 26.

(Advantages of the second embodiment)
In the second embodiment, a part of the peripheral wall portion 12A of the casing main body 12 that defines the suction chamber 26 located on the purge port 18 side of the suction chamber 28 located closest to the atmospheric port 20 on the fluid passage 66. Form a concave shape toward the inside of the suction chamber 26. That is, in the second embodiment, in the suction chamber 26, the region where the distance from the peripheral wall portion 12A of the casing main body 12 becomes large is removed. Therefore, in most of the adsorbent 30 in the adsorption chamber 26, heat conduction with the atmosphere through the peripheral wall portion 12A is likely to occur, so that even if low-temperature air flows in from the adsorption chamber 28, the temperature is high. The decrease can be suppressed. From the above, also in the second embodiment, in the adsorption chamber (in this embodiment, the adsorption chamber 26) where low temperature air tends to flow in, the desorption performance of the adsorbent 30 is deteriorated due to the decrease in temperature. Can be suppressed.

[Modification example]
The canister disclosed in the present specification is not limited to the above-described embodiment, and can be changed to other forms. In the first embodiment, the shapes of the occupied members arranged in the suction chamber 24 and the suction chamber 26 are not limited to the shapes of the occupied member 42 and the occupied member 58, respectively.
The suction chamber 24 may be provided with an occupying member having a truncated cone shape, or the suction chamber 26 may be provided with an occupying member having a conical shape. Further, as shown in FIG. 5, an occupied member having a hollow cylindrical shape may be arranged in at least one of the suction chamber 24 and the suction chamber 26. Alternatively, as shown in FIG. 6, an occupied member having a plurality of (three in FIG. 6) hollow cylinders may be arranged as the occupied portion. The occupying member does not necessarily have to have a base portion as long as it has an occupying portion. In that case, it is desirable to provide an arbitrary positioning means for positioning in the suction chamber in the occupied portion. The occupied portion does not have to be hollow. In that case, it is preferable that the occupied portion is formed of a material having a lower thermal conductivity than the resin forming the casing 10.

The occupied member may be arranged in only one of the suction chamber 24 and the suction chamber 26. When the canister has four or more suction chambers, the occupied member is at least one of the suction chambers after the suction chamber located on the purge port side of the suction chamber located closest to the atmospheric port on the fluid passage. It suffices if it is arranged in one suction chamber.

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

1 Canister 10 Casing 12A Peripheral wall (casing peripheral wall)
16 Tank port 18 Purge port 20 Atmospheric port 24 Suction chamber 26 Suction chamber (second adsorption chamber)
28 Adsorption chamber (1st adsorption chamber)
30 Adsorbent 40,56 Occupied part 42,58 Occupied member

Claims (4)

Casing with tank port, purge port, atmospheric port,
A canister including a plurality of adsorption chambers formed along a purge flow path extending from the atmosphere port to the purge port and filled with an adsorbent inside the casing.
Of the plurality of adsorption chambers, at least one adsorption chamber of the second and subsequent adsorption chambers located closer to the purge port than the first adsorption chamber located closest to the atmospheric port has the casing. An occupying member having an occupying portion occupying the one suction chamber while being separated from the peripheral wall is arranged.
A canister in which the thermal conductivity of the occupied portion of the occupied member is smaller than the thermal conductivity of the casing of the canister. The canister according to claim 1, wherein the occupied member is formed in a hollow shape. Casing with tank port, purge port, atmospheric port,
A canister including a plurality of adsorption chambers formed along a purge flow path extending from the atmosphere port to the purge port and filled with an adsorbent inside the casing.
The casing that defines at least one adsorption chamber of the second and subsequent adsorption chambers located closer to the purge port than the first adsorption chamber located closest to the atmospheric port among the plurality of adsorption chambers. A part of the peripheral wall of the canister forms a concave shape toward the inside of the one suction chamber. The canister according to any one of claims 1 to 3, wherein the adsorption flow path extending from the tank port to the atmosphere port is the suction flow path of the plurality of suction chambers formed along the purge flow path. At least a part of each is shared with the purge flow path.
A canister in which the area of the one adsorption chamber filled with the adsorbent is formed so that the area of the cross section orthogonal to the adsorption flow path decreases toward the atmospheric port.

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