JPH0625654Y2 - Charcoal canister - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention adsorbs and collects fuel evaporative gas generated from a fuel tank of a vehicle or evaporative emission emitted from a fuel system by activated carbon to collect it into the atmosphere. It relates to the structure of a charcoal canister installed to prevent discharge.

[Prior Art] Gasoline vapor generated when gasoline is refueled into an automobile is adsorbed and collected by the activated carbon filled inside to suppress vapor emission to the atmosphere and purge the vapor during engine operation. A charcoal canister used in a vapor recovery system that makes effective use of resources by supplying it to an engine and an evaporation system that adsorbs and captures HC emissions that are about to be released into the atmosphere from fuel systems such as fuel tanks and carburetors by activated carbon. Are well known (eg, US Pat. No. 3,884,204).

This automobile charcoal canister is conventionally constructed as shown in FIG. 8, for example. In the figure, 1 is a canister container, 2 is an evaporative gas inflow port for allowing evaporative gas from a fuel such as gasoline vapor to flow into the container, and 3 is a layer of activated carbon filled in the container. The clean gas (air) that has been adsorbed and collected by the air is discharged from the air introduction port 4. At the time of engine operation, the atmospheric pressure is introduced from the atmospheric air introduction port 4 by utilizing the negative pressure of intake air, the components adsorbed on the activated carbon 3 are purged, and are sent from the purge port 5 to the intake system.
The activated carbon layer 3 is held from both sides by filters 6 and 7 by holding plates 9 and 10 having a large number of vent holes 8.

In a charcoal canister having such a structure, an increase in ventilation resistance causes the following problems.

(A) Poor vapor inflow into the canister If the ventilation resistance of the canister becomes high, it becomes difficult for the vapor to flow into the canister, and normal adsorption of vapor to activated carbon will not occur.

(B) Poor gasoline supply: The vapor recovery system is configured to seal the refueling pipe and the fuel tank with a mechanical or gasoline liquid to prevent vapor backflow to the refueling port, and to flow the vapor to the canister. There is.

However, should the ventilation resistance of the canister increase, gasoline will not flow into the tank.

(C) Poor re-correction of activated carbon: Desorption of HC adsorbed on a canister in an automobile
This is done by using the negative pressure of the engine and introducing the atmosphere into the canister. However, if the ventilation resistance of the canister increases, sufficient air is not introduced into the canister, so that regeneration becomes insufficient and the deterioration of the activated carbon increases.

The causes of increased canister ventilation resistance (pressure loss) are:
The activated carbon may be pulverized or the filter (particularly the filter 7 in FIG. 8) may be clogged, but the most probable cause is the filter clogging. The clogging of the filter is caused by dust or dust in the air introduced when the canister is regenerated. A structure that separates dust and dust in the atmosphere at the time of introduction into the atmosphere by providing a baffle plate and a plurality of compartments is used.
No. 1 and Japanese Utility Model Laid-Open No. 58-146855, however, since neither structure can completely separate dust and dust, if the number of repeated cycles is increased eventually, the filter will be clogged and ventilation will be a problem. Resistance increases.

[Problems to be Solved by the Invention] The present invention focuses on the problem due to the increase in ventilation resistance in the above charcoal canister, and suppresses clogging of the filter to increase the ventilation resistance from the activated carbon layer side to the atmosphere introduction port side at least. The purpose is to secure the flow of evaporative gas from the fuel tank side to the canister side.

[Means for Solving the Problems] A charcoal canister according to the present invention which meets this object has an evaporative gas inflow port capable of injecting an evaporative gas of fuel at one end side and an atmospheric air intake port at which another atmosphere can be introduced at the other end side. A charcoal canister in which a canister container is filled with activated carbon, and between the activated carbon layer in the canister container and the atmosphere introduction port, a plate having a large number of vent holes provided with a filter on the surface of the activated carbon layer side is provided, The plate is provided with a one-way valve that allows only a one-way gas flow in at least a direction that allows a flow from the activated carbon layer side to the atmosphere introduction port side.

That is, as a mode of the one-way valve, a holding plate having a filter on the surface of the activated carbon layer side and having a large number of vent holes and holding the activated carbon layer from the air introduction port side, from the activated carbon layer side to the air introduction port side. There is a mode in which a one-way valve that allows only the flow of 1 is provided. The valve opening pressure of this one-way valve is set to a low pressure.

As another aspect, a plate different from the holding plate that holds the activated carbon layer from the atmosphere introduction port side is provided between the atmosphere introduction port and the holding plate at a distance.
A filter is provided on the surface of the plate on the activated carbon layer side, and a large number of ventilation holes are also provided on the plate, and the plate is opened at a low pressure to allow only the flow from the activated carbon layer side to the atmosphere introduction port side. The first one-way valve and the second one set in the opposite direction, that is, the valve opening pressure higher than that of the first one-way valve which allows only the flow from the atmosphere introduction port side to the activated carbon layer side. A directional valve may be provided.

[Operation] In the charcoal canister as described above, the one-way valve that allows only the flow from the activated carbon layer side to the atmosphere introduction port side is closed at the time of regeneration when the atmosphere is introduced from the atmosphere introduction port. Dust and dust are not collected in the filter portion corresponding to the position, and the filter portion is always kept clean. Therefore, even if other filter parts are clogged, the filter part remains clean and the one-way valve opens for the flow from the activated carbon layer side to the atmosphere introduction port side. The gas easily flows to the atmosphere introduction port side through the clean filter portion, and the increase in ventilation resistance is suppressed. as a result,
Evaporative gas easily flows into the canister from the fuel tank side or the like.

In addition to the above one-way valve, if a second one-way valve that allows only the flow from the atmosphere introduction port side to the activated carbon layer side is provided on the plate as described above, other parts on the plate can be provided. Even if the filter portion at 1 is clogged, a sufficient amount of atmosphere is introduced from the atmosphere introduction port toward the activated carbon layer by opening the second one-way valve. As a result, a good regeneration of the activated carbon is guaranteed.

[Embodiment] Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings.

First Embodiment FIGS. 1 and 2 show a charcoal canister and its internal parts according to an embodiment of the present invention. In the figure, 11 is a canister container, 12 is an evaporative gas inflow port which is provided at one end of the canister container 11 and which can inject evaporative gas from fuel, and 13 is capable of introducing the atmosphere provided at the other end of the canister container 11. Reference numeral 14 denotes an air introduction port, 14 denotes an activated carbon filled in the canister container 11, and 15 denotes a purge port for releasing the gas adsorbed by the activated carbon 14 when the adsorbed component is desorbed. A layer of activated carbon 14 is provided on both sides thereof with a holding plate 18, via filters 16, 17.
Held by 19. Each holding plate 18, 19 has
A large number of vent holes 20 are provided in each.

The holding plate 19 has an air introduction port from the activated carbon layer 14 side.
A one-way valve 21 that allows only the flow of gas to the 13 side is provided. The one-way valve 21 is normally in a state in which the opening (ventilation hole) 22 is closed, but a thin metal plate (for example, stainless steel,
Brass, copper, etc.) and resin (nylon, polyethylene, etc.)
It is designed to open with a small opening pressure of a few mm of water column.

The one-way valve 21 is, as shown in FIGS. 1 and 2,
The one end edge portion of the valve body may simply be fixed on the holding plate 19 and the elasticity of the valve body may be used to open and close the third plate.
As shown in a modification in FIGS. 4 and 5, a spring 24 may be provided on one end side of the valve body 23, and a one-way valve 25 to which a biasing force of the spring 24 in the valve closing direction is applied may be used.

First, the operation of the embodiment apparatus configured as described above
It will be described with reference to the drawings.

For example, the gasoline vapor 26 at the time of refueling is introduced into the canister container 11 through the evaporative gas inflow port 12, only the gasoline component is adsorbed by the activated carbon 14, and the air 27 from which the gasoline component has been removed is vented to the vent hole 20 of the holding plate 17. And is discharged from the air introduction port 13. At the time of regeneration, the atmosphere is introduced from the atmosphere introduction port 13, the gasoline component adsorbed on the activated carbon 14 is desorbed, and the purge port together with the atmosphere.
It is supplied from 15 to the intake system of the engine. When these cycles are carried out for a long period of time, dust or dust in the atmosphere is accumulated on the filter 17 located at the position of the ventilation hole 20 of the holding plate 19, causing clogging. When refueling in such a state in a conventional canister, the air flow resistance of the vent hole 20 increases and it becomes difficult for air to pass, and the internal pressure of the canister container 11 and the fuel tank rises with refueling, and in some cases refueling. Impossible problem occurs. Further, it becomes difficult for the vapor generated in the fuel tank when the engine is stopped to flow into the canister.

However, in the canister structure according to the present invention, even in such a state, the one-way valve 21 opens, so that the air is discharged from the opening 22 and the pressure increase in the canister container 11 and the fuel tank is prevented, and the refueling is performed. Also, the vapor can smoothly flow into the canister. That is, since the one-way valve 21 is closed at the time of regeneration, the atmosphere at the time of regeneration does not pass through the filter 17 portion at the one-way valve 21 portion (opening 22 portion), and this filter 17 portion is always kept in a clean state. Be drunk Therefore, even if the other filter parts are significantly clogged and the air permeability is impaired, the one-way valve 21 opens to discharge the air without increasing the pressure in the canister container 11.

It should be noted that in the above-mentioned embodiment, the actual construction of Japanese Utility Model Publication No.
The atmosphere introduction structure for separating dust and dust disclosed in Japanese Patent Publication No. 1994-242242 may be combined, whereby a further effect in preventing filter clogging can be expected.

Second Embodiment Next, FIGS. 5 to 7 show a charcoal canister according to a second embodiment of the present invention.

In the figure, 31 is a canister container, 32 is an evaporative gas inflow port, 33 is an air introduction port, 34 is activated carbon, 35 is a purge port, 36 is gasoline vapor, 37 is exhaust air, 38 is air introduced at the time of regeneration, 39 Indicates purge gas, respectively. In the present embodiment, the activated carbon layer 34 is held from both sides by filters 40, 41 as in the conventional structure through holding plates 43, 44 having a large number of ventilation holes 42. Further, another plate 45 is provided on the atmosphere introduction port 33 side of the holding plate 44 with a space therebetween. The plate 45 is also provided with a large number of ventilation holes 46, and a filter 47 is provided on the surface on the activated carbon layer 34 side. On this plate 45, a one-way valve 48 that opens and closes the opening 50 by allowing only the flow of gas from the activated carbon layer 34 side to the atmosphere introduction port 33 side, and the gas from the opposite atmosphere introduction port 33 side to the activated carbon layer 34 side And a one-way valve 49 that allows only the flow of the above and opens and closes the opening 51. The one-way valves 48, 49 are also made of, for example, thin plate metal (stainless steel, brass, copper, etc.) or resin (nylon, polyethylene, etc.), and the one-way valve 48 opens with a small pressure of a few mm of water column. As described above, the valve opening pressures of the one-way valves 49 are set so that the one-way valves 49 open at a relatively large pressure of, for example, the initial pressure loss of the canister + 10% or more.

In such a charcoal canister, the one-way valve 48 is closed when the atmosphere is introduced, so that the filter 47 portion of the opening 50 is always kept in a clean state. Even if clogging should occur, the one-way valve 48 opens with a slight valve opening pressure, air is discharged through this portion, and pressure increase on the canister and fuel tank sides is suppressed.

Further, at the time of regeneration, if clogging occurs in the filter 47 portion of the vent hole 46 portion, the one-way valve 49 is opened and the atmosphere is introduced through the opening 51, so a sufficient amount of introduced air is secured,
The early deterioration of the activated carbon 34 is prevented. Also, this one-way valve
Since the valve opening pressure of 49 is set high, the one-way valve 49 does not open until the filter 47 becomes clogged, and the atmosphere is always sent through the vent hole 46 and the filter 47 until then.
Therefore, dust and dust have already been removed from the atmosphere reaching the filter 41, and the life of the filter 41 is significantly improved.

[Effects of the Invention] As described above, when using the charcoal canister of the present invention, at least the activated carbon layer side to the atmosphere introduction port side is provided on the plate provided with the filter and the ventilation hole on the atmospheric introduction port side of the activated carbon layer. Since a one-way valve that allows only the gas flow is provided and even if the filter part other than the one-way valve is clogged, air can be discharged from that part by opening the one-way valve. It is possible to prevent an increase in the pressure in the canister container and hence the fuel tank connected to the canister container, and to achieve smooth refueling, vapor recovery, and smooth vapor flow into the canister. .

[Brief description of drawings]

FIG. 1 is a perspective view of a charcoal canister according to a first embodiment of the present invention, in which a part of the charcoal canister is cut away, FIG. 2 is a plan view of a holding plate of the apparatus of FIG. 1, and FIG. FIG. 4 is a cross-sectional view of a holding plate and a one-way valve according to a modified example of the device, FIG. 4 is a partial plan view of the device of FIG. 3, and FIG. 6 is a plan view of the plate of the apparatus shown in FIG. 1, FIG. 7 is a sectional view taken along line VII-VII of the apparatus shown in FIG. 6, and FIG. 8 is a perspective view of a conventional charcoal canister. Fig. 11, 31 …… Canister container 12, 32 …… Evaporative gas inflow port 13, 33 …… Atmosphere introduction port 14, 34 …… Activated carbon 15, 35 …… Purge port 16, 17, 40, 41 …… Filter 18, 19 , 43, 44 …… Holding plate 20, 42 …… Vent hole 21, 25, 48, 49 …… One-way valve 22, 50, 51 …… Opening 23 …… Valve body 24 …… Spring 26, 36 …… Gasoline Vapor 27, 37 …… Exhaust air 38 …… Introduced atmosphere 39 …… Purge gas 45 …… Plate 46 …… Vent hole 47 …… Filter

Claims (1)

[Scope of utility model registration request] 1. An activated carbon is filled in a canister container having an evaporative gas inflow port capable of injecting a fuel evaporative gas at one end side and an atmosphere introducing port capable of introducing an atmosphere at the other end side, and the inside of the canister container is filled with the activated carbon. In a charcoal canister provided with a plate having a filter on the surface on the side of the activated carbon layer and having a large number of ventilation holes between the activated carbon layer and the air introduction port, the plate allows only one-way gas flow. A charcoal canister, wherein a one-way valve is provided at least in a direction that allows a flow from the activated carbon layer side to the atmosphere introduction port side.