Vaporized Fuel Adsorbing Canister

(1) Field of the Invention

This invention relates to a canister constituting a vaporized fuel adsorbing system used with an internal combustion engine.

(2) Background of the Invention

A vaporized fuel adsorbing system is one in which vaporized fuel produced in the fuel tank for storing fuel for use in the internal combustion engine is collected on the vaporized fuel adsorbing material, such as activated charcoal, contained in the vaporized fuel adsorbing canister (hereinafter canister, for short), and the vaporized fuel collected on the activated charcoal is drawn by suction into the engine for combustion during engine operation.

The canister comprises a hollow body containing charge of activated charcoal, and a cover attached to the hollow body and formed with a vaporized fuel inlet and a vaporized fuel outlet for introducing the vaporized fuel into the hollow body to be collected on the activated charcoal and for discharging the vaporized fuel from the hollow body respectively. The hollow body is provided at either end thereof with a filter member compactly supporting the activated charcoal and preventing incorporation of dust in the vaporized fuel.

The cover of the canister is fluidly connected to the fuel tank through a rubber tube to allow the vaporized fuel produced in the fuel tank to flow therethrough into the cover. During the process of introduction of the vaporized fuel into the cover, the phenomenon of the vaporized fuel changing into a liquid might occur. The liquefield fuel is high in solubility and tends to dissolve oil, such as a mold releasing agent for the rubber tube and grease for a check valve mounted midway in the rubber tube, so that the liquefied fuel containing the dissolved oil and fat flows along the inner wall surface of the cover into the filter member interposed between the cover and the activated charcoal.

The filter member used is of a fine mesh type (10-80 mesh) formed of unwoven cloth or foamed urethane. Thus the oil and fat, such as the mold releasing agent and grease, incorporated in the liquefied fuel would be gradually accumulated on the filter member, until finally they would obturate the filter member.

Obturation of the filter member raises the serious problem that obstruction of the passage of the vaporized fuel through the filter member prevents the vaporized fuel from being collected on the activated charcoal in the hollow body of the canister.

This invention has been developed for the purpose of obviating the aforesaid disadvantages of the prior art. Accordingly the invention has as its object the provision of a canister wherein the filter member interposed between the cover and the vaporized fuel adsorbing agent is kept from being obturated with oil and fat, such as a mold releasing agent, grease, etc.

The outstanding characteristic of the invention is that a porous material member having an oil and fat adsorbing function formed with at least one vaporized fuel permeating opening for allowing vaporized fuel to pass therethrough is located between a filter member interposed between the cover and the vaporized fuel adsorbing agent and the vaporized fuel inlet port formed in the cover, with the liquefied fuel flowing through the vaporized fuel inlet port being led to the porous material member.

FIG. 1 is a diagrammatic view of a vaporized fuel adsorbing system;

FIG. 2 is a vertical sectional view of the vaporized fuel adsorbing canister comprising one embodiment of the invention;

FIG. 3 is a perspective view of the porous material member;

FIGS. 4 and 5 are vertical sectional views of vaporized fuel adsorbing canisters representing modifications of the embodiment shown in FIG. 2;

FIG. 6 is a perspective view of a modification of the porous material member shown in FIG. 3;

FIG. 7 is a vertical sectional view of an example in which the porous material member and the grid are formed into a unitary structure;

FIG. 8 is a perspective view of the unitary structure shown in FIG. 7;

FIG. 9 is a vertical sectional view of the porous material member having a dual structure;

FIG. 10 is a view, on an enlarged scale, of the portion A shown in FIG. 9; and

FIG. 11 is fragmentary vertical sectional view of the vaporized fuel adsorbing canister comprising another embodiment of the invention which is of type different from the canister shown in FIG. 2.

The invention will now be described in detail by referring to its embodiments shown in the drawings. FIG. 1 shows the construction of a vaporized fuel adsorbing system used with an internal combustion engine provided with a carburetor. The numeral 10 designates a suction conduit receiving a supply of fuel through a nozzle 16 from a float chamber 14 in accordance with the opening of a throttle valve 12. The float chamber 14 receives a supply of fuel from a fuel tank 18 by a fuel pump, not shown. Meanwhile an upper portion of the float chamber 14 and an upper portion of the fuel tank 18 are connected to a canister 24 via rubber tubes 20 and 22 respectively. Upon a key switch 26 being brought to an open position during engine shutdown, an air vent 28 opening in the float chamber 14 is closed by an electromagnetic valve 30 and the vaporized fuel produced in the float chamber 14 is led via the rubber tube 20 to the canister 24 where it is collected on a charge of vaporized fuel adsorbing agent, such as activated charcoal 32. The vaporized fuel produced in the fuel tank 18 is introduced into the canister 24 through the rubber tube 22 by opening a check valve 34, to be collected on the activated charcoal 32. During engine operation, a subatmospheric pressure is produced in the vicinity of the throttle valve 12 and opens a check valve 38 mounted midway in a rubber tube 36 connecting an upper portion of the canister 24 to the suction conduit 10, so that the vaporized fuel collected on the activated charcoal 32 is released therefrom and supplied to the engine through the suction conduit 10. In the embodiment shown, the vaporized fuel produced in the float chamber 14 of the carburetor is introduced into the canister 24 to be collected on the activated charcoal 32 because of the use of the carburetor with the internal combustion engine. However, when the engine is provided with a fuel injection system, the vaporized fuel from the fuel tank 18 alone has to be led to the canister 24 to be collected on the activated charcoal 32, because the fuel injection system is not provided with a float chamber.

The vaporized fuel adsorbing system of the aforesaid construction has, as described in the Background of the Invention, the problem that the vaporized fuel liquefied in the rubber tube 22 dissolves a mold releasing agent for the rubber tube 22 and grease in the check valve before flowing into the canister 24, thereby obturating the filter members therein. The vaporized fuel adsorbing system according to the invention is capable of avoiding the obturation of the filter members with the mold releasing agent and grease. Preferred embodiments of the invention will now be described.

FIG. 2 shows one embodiment wherein a first filter member 42 is located at one end of a hollow body 40 formed with a first opening 40A and a second opening 40B and a second filter member 44 is located at the other end of the hollow body 40, and the activated charcoal 32 is packed in the hollow body 40 between the two filter members 42 and 44 formed of nonwoven cloth, foamed urethane, etc. In order to hold the activated charcoal 32 in a compactly packed condition, a first grid 46 and a second grid 48 formed of metal are arranged adjacent the filter members 42 and 44 on a side thereof opposite the activated charcoal 32 respectively. The first grid 46 is formed with a multiplicity of vaporized fuel permeating openings 50 for allowing the vaporized fuel to pass therethrough, while the second grid 48 is formed with a multiplicity of air permeating openings 52 for allowing purging air to pass therethrough. A cover 54 is attached to an end of the hollow body 40 at which the first opening 40A is formed and the first filter member 42 and the first grid 46 are mounted, to close the first opening 40A. The cover 54 is formed with vaporized fuel inlet ports 56 and 58 connected to the rubber tubes 20 and 22 respectively and with a vaporized fuel outlet port 60 connected to the rubber tube 36. The vaporized fuel inlet port 56 may be dispensed with when the system is used with an internal combustion engine provided with a fuel injection system. A porous material member 66 formed of nonwoven cloth for adsorbing oil and fat is fitted in the cover 54 in a position between the vaporized fuel inlet ports 56 and 58 and the first grid 46 to define spaces 62 and 64 in the cover 54. The porous material member 66 is maintained in contact with an inner wall surface 54A of the cover 54 for adsorbing the fuel containing oil and fat flowing along the inner wall surface 54A of the cover 54, so that the inner wall surface 54A will serve as the path of flow of the liquefied fuel. As shown in FIG. 3, the porous material member 66 is formed with a multiplicity of vaporized fuel permeating openings 68 for allowing vaporized fuel to pass therethrough. The number and size of the vaporized fuel permeating openings 68 are selected such that the total vaporized fuel permeating area of the member 66 is enough to allow sufficient ventilation to be maintained through the porous material member 66 even if the member 66 is obturated with oil and fat. The porous material member 66 has a density which is equal to or higher than that of the first filter member 42. However, the invention is not limited to this arrangement, so long as oil and fat can be collected on the porous material member 66 even if the density of the member 66 is lower than that of the first filter member 42 (or the pores are larger in size).

In addition to unwoven cloth, paper, foamed urethane, etc., may also be used for forming the porous material member 66.

The reason why the space 62 is provided is because the presence of the space 62 enables the vaporized fuel to come into contact with the entire surface of the porous material member 66, and the space 64 is intended to prevent the vaporized fuel permeating openings 68 of the porous material member 66 from being closed by the first grid 46 when the member 66 contacts the first grid 46.

In the aforesaid constructon, when the vaporized fuel produced in the fuel tank 18 and float chamber 14 is changed into a liquid state as it flows through the rubber tubes 20 and 22, the liquefied fuel might dissolve the mold releasing agent of the rubber tubes 20 and 22 and the grease in the check valve 34 before flowing into the vaporized fuel inlet ports 56 and 58 of the canister 24. The liquefied fuel containing oil and fat flows along the inner wall surface 54A of the cover 54 to be adsorbed on the porous material member 66. The porous material member 66 allows the liquefied fuel itself to pass therethrough but does not allow the oil and fat to pass therethrough, so that they are collected on the member 66. Thus the liquefied fuel itself flows through the space 64, vaporized fuel permeating openings 50 of the first grid 46 and first filter member 42 to be collected on the activated charcoal 32. It goes without saying that the vaporized fuel passes through the vaporized fuel permeating openings 68 of the porous material member 66, vaporized fuel permeating openings 50 of the first grid 46 and first filter member 42 to be collected on the activated charcoal 32.

When the vaporized fuel collected on the activated charcoal 32 is desired to be released therefrom, the air introduced through the second filter member 44 is passed through the charge of activated charcoal 32 to cause the vaporized fuel to be released from the activated charcoal 32 and passed through the first filter member 42, vaporized fuel permeating openings 50 of the first grid 46 and vaporized fuel permeating openings 68 of the porous material member 66 to be discharged from the canister 24 through the vaporized fuel outlet port 60 and supplied to the engine.

The first filter member 42 is prevented from being obturated with oil and fat due to the oil and fat adsorbing function of the porous material member 66. This allows clean vaporized fuel to be collected on the activated charcoal 32 at all times through the first filter member 42, thereby solving the serious problem encountered by the vaporized fuel adsorbing system of the prior art that no vaporized fuel is collected on the activated charcoal 32. The porous material member 66 is designed to be able to collect oil and fat in amounts such that it is still capable of collecting oil and fat when the total amounts of oil and fat flowing into the cover 54 have been collected thereby.

Modifications of the embodiment shown in FIG. 2 will be described by referring to FIGS. 4 and 5. FIG. 4 shows a first embodiment in which a porous support member 70 for supporting the porous material member 66 is fitted in the space 64 defined between the porous material member 66 and first grid 46. The porous support member 70 is formed of glass wool and formed with larger pores than the porous material member 66. The function of the porous support member 70 is to keep the porous material member 66 in flat condition when the porous material member 66 is unable to keep itself flat by itself. When the porous material member 66 itself has rigidity as shown in FIG. 2, the support member 70 may be dispensed with.

FIG. 5 shows a second modification including, in addition to the construction of the first modification, shown in FIG. 4, a liquefied fuel diffusing porous member 72 located in the space 62 defined between the vaporized fuel inlet ports 56 and 58 and the vaporized fuel outlet port 60 in the cover 54 and the porous material member 66. The liquefied fuel diffusing porous member 72 is formed of glass wool and has larger pores than the porous material member 66. The function of the liquefied fuel diffusing porous member 72 is to prevent the liquefied fuel flowing through the vaporized fuel inlet ports 56 and 58 from flowing along the inner wall surface 54A of the cover 54 alone, to thereby cause the liquefied fuel to come into contact with the entire surface of the porous material member 66. This function can be explained by the well known capillary action.

FIG. 6 shows a modification of the porous material member in which the configuration of the member is somewhat varied. As shown, the porous material member 66A is formed with a single ventilating opening 68A of substantially the same area as the total area of the vaporized fuel permeating openings 68 of the porous material member 66 shown in FIG. 3. It will be appreciated in FIGS. 3 and 6 that the vaporized fuel permeating openings essentially need be more than one in number.

FIGS. 7 and 8 show the porous material member 66 and the first grid 46 being formed into a unitary structure. The porous material member 66 is adhesively connected to the first grid 46 in such a manner that the vaporized fuel permeating openings 68 of the porous material member 66 are in coincidence with the vaporized fuel permeating openings 50 of the first grid 46. The assembly of porous material member 66 and first grid 46 is produced by first adhesively connecting them together and then punching them with a press.

FIGS. 9 and 10 show a modification of the porous material member in which the construction of the member is somewhat varied. The porous material members shown in FIGS. 3, 6 and 7 are all formed of material of the same density. However, the porous material member shown in FIG. 9 is characterized by having a double layer structure. In the case of a porous material member of material of the same density, a paucity of the area for adsorbing oil and fat makes it necessary to increase its thickness. The construction shown in FIG. 9 is advantageous in decreasing the thickness of the porous material layer. In FIG. 9, the porous material member assembly 66 includes a member 66B of lower density having larger pores than the porous material member 66 shown in FIGS. 3, 6 and 7, and a member 66C similar to the member 66 shown in FIGS. 3, 6 and 7, which are formed unitarily with the member 66B being disposed on the side of the vaporized fuel inlet ports 56 and 58. As shown in FIG. 10, the oil and fat pass through the member 66B to be collected on the member 66C, and when the member 66C is obturated the member 66B collects the oil and fat thereon. The member 66B is capable of adsorbing the oil and fat in greater amounts than the member 66C because of lower density, thereby enabling the thickness of the porous material member assembly 66 to be reduced.

FIG. 11 shows canister of a type distinct from that of the canister shown in FIG. 2, in which the invention is incorporated. As shown, the vaporized fuel outlet port 60 communicates with a pocket 74 extending through the porous material member 66, first grid 46 and first filter member 42 into the activated charcoal 32. A filter 76 and a grid 78 are mounted in the pocket 74. Vaporized fuel is introduced through the vaporized fuel inlet ports 56 and 58 into the canister 24 in which it is collected on the activated charcoal 32, in the same manner as described by referring to FIG. 2, and the vaporized fuel collected on the activated charcoal 32 is discharged through the vaporized fuel outlet port 60 after passing through the filter 76, grid 78 and pocket 74. In this embodiment, the porous material member 66 has the same function and achieves the same effects as described by referring to the embodiment shown in FIG. 2.

From the foregoing description, it will be appreciated that the provision of a porous material member for adsorbing the oil and fat that might be incorporated in the liquefied fuel eliminates the disadvantage of the prior art that the filter member is obturated, thereby allowing the vaporized fuel to be collected on the vaporized fuel adsorbing agent without fail.