JP2022040713A - Evaporated fuel treatment device - Google Patents

Abstract

To provide an evaporated fuel treatment device for reducing cost by simplifying a storage structure for an adsorbing material and a heat storage material to be stored in a storage part on the atmospheric port side, while reducing volume of the storage part on the atmospheric port side.SOLUTION: An evaporated fuel treatment device 10 includes a casing 12 formed with a tank port 17, a purge port 18, and an atmospheric port 19, and an adsorbent C being filled in the casing 12 and capable of adsorbing evaporated fuel flowing in from a fuel tank or desorbing the adsorbed evaporated fuel. The internal of the casing 12 ranging from the atmospheric port 19 to the purge port 18 and the tank port 17 is parted into a plurality of storage parts 41, 42, 43, the storage parts 41, 42, 43 is each filled with the adsorbent C. In the storage part 43 nearest the atmospheric port 19 of the casing 12, a polypropylene pellet type heat storage material P is stored while being mixed with the adsorbent C.SELECTED DRAWING: Figure 1

Description

The present invention relates to an evaporative fuel processing apparatus that processes evaporative fuel generated in a fuel tank.

Patent Document 1 describes a technique related to the above-mentioned evaporated fuel processing apparatus. The evaporative fuel processing apparatus described in Patent Document 1 includes a casing, which includes a tank port connected to the air layer portion of the fuel tank, a purge port connected to the intake passage of the engine, and open to the atmosphere. An atmospheric port is formed. The inside of the casing is a gas passage folded back in a substantially U shape, and a tank port and a purge port are formed on one end side of the gas passage. Further, an atmospheric port is formed on the other end side of the gas passage. In the casing, a first accommodation chamber, a passage portion, a second accommodation chamber, and a third accommodation chamber are formed in order from the tank port and the purge port side.

The first and second storage chambers of the casing are filled with a granular adsorbent such as activated carbon. Further, the adsorption element is housed in the third storage chamber closest to the atmospheric port. The suction element is formed in the form of a three-layer structure in which a suction layer is sandwiched between a pair of breathable nonwoven fabric sheets. As the adsorption layer, a material in which an adsorbent and a heat storage material that suppresses a temperature change of the adsorbent are fixed with a hot melt binder is used. In this way, since the adsorbent and the heat storage material that suppresses the temperature change of the adsorbent are stored in the third storage chamber closest to the atmospheric port, the evaporative fuel adsorption performance or the evaporative fuel desorption performance of the adsorbent Can be held well. As a result, it is possible to reduce the amount of evaporative fuel remaining in the adsorbent after the desorption of the evaporative fuel, and it is possible to reduce the amount of evaporative fuel leaking from the atmospheric port.

Japanese Unexamined Patent Publication No. 2008-25365

In the evaporative fuel processing apparatus described in Patent Document 1, the adsorption element having a three-layer structure in which the adsorption layer is sandwiched between the non-woven fabric sheets is accommodated in the third accommodation chamber closest to the atmospheric port. Further, the adsorption layer is formed by fixing the adsorbent and the heat storage material with a hot melt binder. Therefore, the accommodation structure of the adsorbent and the heat storage material accommodated in the third accommodation chamber becomes complicated and costly. Further, since the accommodation structure is complicated, the volume of the third accommodation chamber becomes large.

The present invention has been made to solve the above problems, and the problem to be solved by the present invention is to simplify the accommodation structure of the adsorbent and the heat storage material accommodated in the accommodation portion on the atmosphere port side. To reduce costs. In addition, the volume of the accommodating portion on the atmosphere port side is to be reduced.

The above-mentioned problems are solved by each invention. The first invention is a casing in which a tank port communicated with a gas layer portion of a fuel tank, a purge port communicated with an intake passage of an engine, and an atmospheric port open to the atmosphere are formed, and the inside of the casing. It is an evaporative fuel processing apparatus having an adsorbent that is filled in and can adsorb the evaporative fuel that has flowed in from the tank port or can desorb the adsorbed evaporative fuel, and the inside of the casing is from the atmospheric port. The purge port and the tank port are divided into a plurality of accommodating portions, each accommodating portion is filled with the adsorbent, and the accommodating portion of the casing closest to the atmospheric port is made of polypropylene. The pellet-shaped heat storage material is stored in a state of being mixed with the adsorbent.

According to the present invention, the adsorbent and the polypropylene heat storage material that suppresses the temperature change of the adsorbent are housed in the accommodating portion closest to the atmospheric port of the casing. Therefore, by suppressing the temperature change of the adsorbent, the evaporative fuel adsorption performance or the evaporative fuel desorption performance of the adsorbent can be well maintained. This makes it possible to reduce the amount of evaporative fuel remaining in the adsorbent housed in the accommodating portion closest to the atmospheric port of the casing after the evaporative fuel is desorbed. As a result, the amount of evaporative fuel leaking from the atmospheric port can be reduced. Further, by adopting a pellet-shaped heat storage material made of polypropylene, it is possible to suppress the complication of the structure. Further, since the polypropylene pellet-shaped heat storage material and the adsorbent are stored in the casing in a mixed state, the storage structure of the adsorbent and the heat storage material is simple. Further, since the accommodation structure is simple, the volume of the accommodation portion on the atmosphere port side can be reduced.

According to the second invention, the amount of the heat storage material mixed with the adsorbent in the accommodating portion closest to the atmospheric port of the casing is 20% or more when the capacity of the adsorbent is 100%. Therefore, it is possible to effectively suppress the temperature change of the adsorbent due to the adsorption or desorption of the evaporated fuel. As a result, the amount of evaporative fuel remaining in the adsorbent after desorption of the evaporative fuel can be surely reduced, and the amount of evaporative fuel leaking from the atmospheric port can be reduced.

It is a plan sectional view of the evaporative fuel processing apparatus (canister) which concerns on Embodiment 1 of this invention. It is a graph showing the relationship between the mixing ratio of the pellet of the adsorbent and the pellet of the heat storage material, and the amount of leakage of the evaporated fuel leaking from the atmospheric port of the canister.

[Embodiment 1]
Hereinafter, the evaporated fuel treatment apparatus according to the first embodiment of the present invention will be described with reference to FIGS. 1 and 2. The evaporative fuel processing device according to the present embodiment is a canister 10 mounted on a vehicle such as an automobile. Here, the front-back and left-right directions shown in FIG. 1 represent the front-back and left-right directions of the canister 10, and do not limit the mounting direction.

<About the configuration of the canister 10>
As shown in FIG. 1, the canister 10 includes a resin casing 12 formed in a substantially quadrangular box shape. The casing 12 is composed of a casing main body 13 and a lid member 14 that closes the rear opening 13x of the casing main body 13. The casing main body 13 includes a square cylinder portion 13a and a cylindrical portion 13b arranged on the right side of the square cylinder portion 13a. The square tubular portion 13a and the cylindrical portion 13b of the casing main body 13 extend in parallel in the front-rear direction and are connected to each other via the partition wall 13c. Further, the casing main body 13 includes a front end wall 13d that closes the front end of the square cylinder portion 13a, and a front end wall 13e that closes the front end of the cylindrical portion 13b. The internal space partitioned by the partition wall 13c in the casing main body 13 is communicated with each other by the communication chamber 15 formed between the casing main body 13 and the lid member 14. As a result, a U-shaped gas passage including an internal space formed by the square tubular portion 13a, an internal space provided by the communication chamber 15 and a cylindrical portion 13b is formed inside the casing 12.

The tank port 17 and the purge port 18 communicating with the internal space of the square cylinder portion 13a are formed so as to project forward on the front end wall 13d of the square cylinder portion 13a of the casing main body 13. The tank port 17 communicates with the air layer portion of the fuel tank (not shown) of the vehicle. The purge port 18 communicates with the intake passage of the engine. Further, on the front end wall 13e of the cylindrical portion 13b of the casing main body 13, an atmospheric port 19 communicating with the internal space of the cylindrical portion 13b is formed so as to project forward. Atmospheric port 19 is open to the atmosphere. In the internal space of the square cylinder portion 13a of the casing main body 13, the position near the front end wall 13d is partitioned between the tank port 17 side and the purge port 18 side by the partition wall 13f. A front end filter 20 is installed at the front end of the portion partitioned by the partition wall 13f.

At the rear end opening 13h of the square tube portion 13a of the casing main body 13, for example, a resin-made breathable perforated plate 21 is installed so as to close the rear end opening 13h. A rear end filter 22 is laminated on the front surface side of the perforated plate 21. Further, a spring member 23 for urging the perforated plate 21 forward is interposed between the perforated plate 21 and the lid member 14. In this way, the first accommodating portion 41 is formed between the front end filter 20 and the rear end filter 22 in the square tube portion 13a of the casing main body 13.

A front end filter 31 is installed inside the front end wall 13e in the cylindrical portion 13b of the casing main body 13. Further, in the internal space of the cylindrical portion 13b, a transverse filter 32 is installed at a position closer to the front portion so as to traverse the inside of the cylindrical portion 13b. Further, in the rear end opening 13j of the cylindrical portion 13b, for example, a resin-made breathable perforated plate 33 is installed so as to close the rear end opening 13j. A rear end filter 34 is laminated on the front surface side of the perforated plate 33. Further, a spring member 35 for urging the perforated plate 33 forward is interposed between the perforated plate 33 and the lid member 14. As described above, in the cylindrical portion 13b of the casing main body 13, the third accommodating portion 43 is formed between the front end filter 31 and the transverse filter 32, and the second accommodating portion 43 is formed between the transverse filter 32 and the rear end filter 34. The portion 42 is formed.

The first accommodating portion 41 between the front end filter 20 and the rear end filter 22 in the square cylinder portion 13a of the casing main body 13 is filled with an adsorbent C capable of adsorbing evaporative fuel or desorbing the adsorbed evaporated fuel. There is. Further, the adsorbent C and the polypropylene heat storage material P that suppresses the temperature change of the adsorbent C are mixed in the third accommodating portion 43 between the front end filter 31 and the transverse filter 32 in the cylindrical portion 13b of the casing main body 13. It is filled in the state of being filled. Further, the adsorbent C is filled in the second accommodating portion 42 between the transverse filter 32 and the rear end filter 34 in the cylindrical portion 13b of the casing main body 13.

<General functions of canister 10>
When the engine of the vehicle is stopped, the evaporative fuel generated in the fuel tank flows into the first accommodating portion 41 from the tank port 17 of the canister 10 together with the air, and the evaporative fuel flows into the adsorbent C of the first accommodating portion 41. Is adsorbed on. Further, the evaporated fuel that has passed through the adsorbent C of the first accommodating portion 41 passes through the communication chamber 15 and is adsorbed by the adsorbent C of the second accommodating portion 42 and the adsorbent C of the third accommodating portion 43. Then, a gas consisting almost exclusively of air is released into the atmosphere from the atmospheric port 19. Next, when the condition for driving the engine and performing the purge process is satisfied, the intake negative pressure of the engine is applied to the inside of the casing 12 via the purge port 18 of the canister 10. As a result, air is introduced into the third accommodating portion 43 as purge air from the atmosphere port 19. The purge air flows from the third accommodating portion 43 to the second accommodating portion 42, the communication chamber 15, and the first accommodating portion 41, and is guided from the purge port 18 to the intake passage of the engine. In the process of the purge air passing through the third accommodating portion 43, the second accommodating portion 42, and the first accommodating portion 41, the adsorbent C is purged by the purge air, and the adsorbed evaporative fuel is separated from the adsorbent C. Then, the evaporated fuel desorbed from the adsorbent C is guided to the intake passage of the engine together with the purge air, and is burned in the combustion chamber of the engine.

<About the adsorbent C and the heat storage material P>
The adsorbent C is a pellet obtained by molding powdered activated carbon into a predetermined size, and the particle size is set to, for example, 2 mm to 2.5 mm. Here, the adsorbent C generates heat when adsorbing the evaporated fuel, and the temperature rises. Then, the adsorption capacity of the adsorbent C gradually decreases as the temperature rises. Further, the heat of the adsorbent C is taken away when the evaporative fuel is desorbed, and the temperature becomes low. Then, the desorption ability of the adsorbent C gradually decreases as the temperature decreases. Therefore, in order not to reduce the adsorption capacity and the desorption capacity of the adsorbent C, it is necessary to suppress the temperature change of the adsorbent C.

When the desorption ability of the adsorbent C decreases, the amount of evaporative fuel remaining in the adsorbent C becomes relatively large even after the adsorbent C is purged to desorb the evaporated fuel. If there is a large amount of evaporative fuel remaining in the adsorbent C, the evaporative fuel is likely to be released into the atmosphere from the atmospheric port 19. As a countermeasure, in the canister 10 according to the present embodiment, the third accommodating portion 43 closest to the atmospheric port 19 is filled with the adsorbent C and the polypropylene heat storage material P (large specific heat) in a mixed state. The decrease in the desorption ability of the adsorbent C is suppressed. Here, the heat storage material P is a pellet of polypropylene resin, and is set to, for example, 2 mm to 2.5 mm so that the particle size is equal to the particle size of the adsorbent C. This makes it possible to uniformly mix the adsorbent C and the heat storage material P.

<About the mixing ratio of the adsorbent C and the heat storage material P>
Next, the mixing ratio of the adsorbent C and the heat storage material P will be described with reference to FIG. FIG. 2 is a graph showing the relationship between the ratio of the capacity of the heat storage material P to the capacity of the adsorbent C (pellet mixing ratio) and the amount of leaked fuel from the atmospheric port 19. Here, for example, the pellet mixing ratio of 20% means that the ratio of the capacity of the heat storage material P is 20% when the capacity of the adsorbent C is 100%. Similarly, the pellet mixing ratio of 40% means that the ratio of the capacity of the heat storage material P is 40% when the capacity of the adsorbent C is 100%. Further, the amount of leakage of the evaporated fuel is determined by actually measuring the concentration of hydrocarbon HC, which is the main component of the evaporated fuel, in the air with a densitometer. As shown in FIG. 2, when the pellet mixing ratio was 0%, that is, when only the adsorbent C was filled in the third accommodating portion 43, the leakage amount of the evaporated fuel was 22 mg. However, as the mixing ratio of the heat storage material P to the adsorbent C in the third accommodating portion 43 is increased, the temperature change of the adsorbent C and the deterioration of the desorption performance of the evaporated fuel are suppressed, and the heat storage material P is suppressed from the atmosphere port 19. Leakage of evaporative fuel will be reduced.

Therefore, from the viewpoint of reducing the amount of the evaporated fuel leaking from the atmospheric port 19, it is preferable that the mixing ratio of the heat storage material P with respect to the adsorbent C is large. However, if the mixing ratio of the heat storage material P to the adsorbent C is made larger than necessary, the volume of the third accommodating portion 43 becomes unnecessarily large. Therefore, in the present embodiment, in order to suppress the leakage amount of the evaporated fuel to about 20 mg and further to minimize the volume of the third accommodating portion 43, the mixing ratio of the heat storage material P to the adsorbent C is used. The adsorbent C is set to 20% to 23% with respect to 100%. Further, the polypropylene resin used as the heat storage material P has a specific gravity of about 0.9, which is lighter than the polyamide resin generally used as the heat storage material (specific gravity of about 1.12). Therefore, the weight of the canister 10 can be reduced.

<Correspondence between the term according to the first embodiment and the term according to the present invention>
The third accommodating portion 43 in the casing 12 of the canister 10 according to the present embodiment corresponds to the accommodating portion closest to the atmospheric port of the present invention.

<About the advantages of the canister 10 according to this embodiment>
According to the canister 10 according to the present embodiment, the adsorbent C and the polypropylene heat storage material that suppresses the temperature change of the adsorbent C are provided in the third accommodating portion 43 (accommodation portion closest to the atmospheric port) of the casing 12. P is stored. Therefore, by suppressing the temperature change of the adsorbent C, the evaporative fuel adsorption performance or the evaporative fuel desorption performance of the adsorbent C can be satisfactorily maintained. As a result, the amount of evaporative fuel remaining in the adsorbent C housed in the third accommodating portion 43 after the desorption of the evaporative fuel can be reduced, and the amount of evaporative fuel leaking from the atmospheric port 19 can be reduced. Further, since the heat storage material P made of polypropylene is stored in the third storage portion 43 of the casing 12 in a state of being mixed with the adsorbent C, the storage structure of the adsorbent C and the heat storage material P is simple. Further, since the accommodating structure is simple, the volume of the third accommodating portion 43 can be reduced.

Further, the mixing ratio of the heat storage material P to the adsorbent C of the third accommodating portion 43 is 20% or more when the adsorbent C is 100%. Therefore, the amount of evaporative fuel remaining in the adsorbent C after desorption of the evaporative fuel can be reduced, and the amount of evaporative fuel leaking from the atmospheric port 19 can be reduced. Further, since the adsorbent C and the heat storage material P are formed in a pellet shape and have the same size, the heat storage material P can be uniformly mixed with the adsorbent C so as not to be unevenly distributed.

<Change example>
Here, the present invention is not limited to the above embodiment, and changes can be made without departing from the gist of the present invention. For example, in the present embodiment, an example is shown in which the mixing ratio of the heat storage material P to the adsorbent C of the third accommodating portion 43 is 20% to 23% when the adsorbent C is 100%. However, it is also possible to set the mixing ratio of the heat storage material P to about 23% to 30%. Further, in the present embodiment, an example in which the particle size of the pellet of the adsorbent C and the pellet of the heat storage material P is set to 2 mm to 2.5 mm is shown. However, it is also possible to appropriately change the particle size while the pellets of the adsorbent C and the pellets of the heat storage material P have the same particle size.

10 ... Canister (evaporated fuel processing device)
12 ... Casing 13 ... Casing body 14 ... Lid member 17 ... Tank port 18 ... Purge port 19 ... Atmospheric port 41 ... First accommodating section 42 ... Second accommodating Part 43 ... Third casing (the casing closest to the atmospheric port)
C ... Adsorbent P ... Heat storage material

Claims (2)

A casing in which a tank port communicating with the air layer of the fuel tank, a purge port communicating with the intake passage of the engine, and an atmosphere port open to the atmosphere are formed, and the casing is filled. An evaporative fuel processing apparatus having an adsorbent capable of adsorbing evaporative fuel flowing in from the tank port or desorbing adsorbed evaporative fuel.
The inside of the casing is divided into a plurality of accommodating portions between the atmospheric port, the purge port, and the tank port, and each accommodating portion is filled with the adsorbent.
An evaporative fuel treatment device in which a polypropylene pellet-shaped heat storage material is stored in a state of being mixed with the adsorbent in a housing portion of the casing closest to the atmospheric port. The evaporative fuel processing apparatus according to claim 1.
An evaporative fuel treatment apparatus in which the amount of the heat storage material mixed with the adsorbent in the accommodating portion closest to the atmosphere port of the casing is 20% or more when the capacity of the adsorbent is 100%.

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