JPS6332980B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel evaporation prevention device installed in a vehicle.

As this type of fuel evaporation prevention device, a fuel vapor adsorbent layer is provided inside the container, and fuel vapor generated in the fuel tank, etc. is guided into the adsorbent layer and adsorbed, and when the internal combustion engine is operating, the negative pressure in the intake passage of the engine is reduced. Air is sucked into the container using the air, the fuel vapor adsorbed on the adsorbent layer is desorbed by this intake air, and a mixture with air is supplied to the intake passage (hereinafter referred to as , called Canista).

By the way, granular activated carbon has conventionally been generally used for the adsorbent layer in a canister. However, the canister is constantly exposed to vibrations when the vehicle is running.
Especially when driving on rough roads, the granular activated carbon in the adsorbent layer rubs against each other and becomes powder due to the extremely strong vibrations.
The filters that hold down the top and bottom surfaces of the adsorbent layer may become clogged, increasing airflow resistance and reducing the desorption effect of adsorbed fuel through air circulation.Also, fine activated carbon powder may pass through the filter and be guided into the intake passage, leading to the engine. There was a problem with negative effects. Furthermore, when the granular activated carbon becomes finely powdered, its adsorption capacity also decreases, resulting in the problem that it no longer functions as a canister.

Therefore, as an alternative to the granular activated carbon layer, a canister has been proposed that incorporates an adsorbent layer in which activated carbon fibers (hereinafter referred to as activated carbon fiber paper) formed into paper or felt shapes are laminated.

On the other hand, another problem that occurs in canisters with adsorbent layers, either granular activated carbon layer or activated carbon fiber paper layer, is that the fuel vapor that enters the container from the fuel vapor inlet does not pass through the adsorbent layer and is directly vaporized. This is a problem derived from the derivation port. In other words, when fuel vapor is introduced into the container from the fuel vapor inlet during desorption of the adsorbed fuel, the fuel vapor bypasses the air-fuel mixture outlet without flowing into the adsorbent layer, thereby increasing the air-fuel ratio. Temporarily becomes too rich, causing problems with engine operation and exhaust.

The present invention was developed in view of the above circumstances, and the adsorbent layer is composed of a laminate of activated carbon fiber paper, and the fuel vapor introduced into the container during the desorption process does not pass through the adsorbent layer. It is an object of the present invention to provide a canister that does not directly bypass the air-fuel mixture outlet, and to provide a canister in which an adsorbent layer made of activated carbon fiber paper can be easily formed.

To summarize the configuration of the canister according to the present invention,
Inside the container, a guide tube with a closed end through which fuel vapor flows from the fuel vapor inlet is provided in the axial direction of the container.
An adsorbent layer is formed by winding activated carbon fiber paper in a laminated manner around a guide tube, and the interior of the container is filled with the adsorbent layer, and the adsorbent layer has a space that traverses it in the radial direction. The guide tube has a structure in which the inside of the tube and the space are communicated through a through hole provided in the middle of the guide tube.

In the canister of the present invention, the fuel vapor that has entered the container first enters the guide tube, and then flows through the space into the adsorption layer where it is adsorbed. Therefore, even during the desorption operation, fuel vapor flows from the space into the adsorbent layer through the same route as described above, and therefore does not flow directly to the air-fuel mixture outlet. Further, since the guide tube can be used as a core material for winding activated carbon fiber paper at the same time, the adsorbent layer can be easily formed. Note that if the space is filled with an adsorbent having good air permeability, the space can also function as an adsorbent layer.

Hereinafter, details of the present invention will be explained with reference to illustrated embodiments.

In the first embodiment shown in FIGS. 1 to 3,
The container 1 consists of a container body 1a having a circular cross section and a lid 1a caulked to the upper open end of the container body 1a.

A thick valve base body 2 is formed in the center of the lid 1b, and one ends of a fuel vapor introduction pipe 3 and a mixture discharge pipe 4 are attached to the base body 2. The inlet pipe 3 and the outlet pipe 4 communicate with a fuel tank and an intake pipe of an internal combustion engine, respectively, which are not shown. A further fuel vapor introduction pipe 30 is attached to the lid 1b, thereby communicating the vaporizer float chamber and the container 1.

The valve base 2 is provided with a fuel vapor inlet 5 and an air inlet 6 that communicate with the fuel vapor inlet pipe 3, and a mixture outlet 7 that communicates with the mixture outlet pipe 4, each of which is provided with springs 8 and 9. , 10, check balls 11, 12, 13 are provided.

An air introduction port 10a is formed in the end surface of the container body 1a facing the lid 1b.

The upper end of a fuel vapor guide pipe 20 is fitted into a groove formed around the fuel vapor inlet 5 at the center of the lower surface of the valve base 2 inside the container via a sealing material, and the lower end of the guide pipe 20 is connected to the container main body 1a. It is supported at the center of a punched metal plate 14b installed in the shape of a shelf at the bottom of the frame. This guide tube 20 is vertically separated by a partition plate 20a provided at the upper part of the tube, and a plurality of through holes 20b are provided in the tube wall directly above the partition plate 20a in the circumferential direction.

An adsorbent layer 15 formed by winding a band-shaped activated carbon fiber paper 15a in layers is formed around the guide tube 20, and the container body 1a is filled with this adsorbent layer 15. As activated carbon fiber paper,
For example, when Japanese paper is manufactured by mixing activated carbon fiber with adhesive fibers such as fibrous polyvinyl alcohol and cellulose fiber, it can be easily manufactured by papermaking in the same manner. A disc-shaped space 18 is formed in the adsorbent layer 15 in the radial direction at a position corresponding to the through hole 20b of the guide tube 20.

2 and 3 show an example of a method for forming the adsorption layer 15. FIG. A linear notch 18a is provided in the band-shaped activated carbon fiber paper 15a from one longitudinal end to the other end. Note that a portion without the notch 18a remains on the other end side. The fiber paper 15a is then wound around the guide tube 20 until its diameter matches the inner diameter of the container body 1a, with the notch 18a aligned with the through hole 20b of the guide tube 20. The adsorbent layer 15 is formed by press-fitting the thus obtained laminate into the container body. Notch 18 above
a is the space 18 of the adsorbent layer 15. After press-fitting the adsorbent layer 15 into the container body 1a, a punching metal 14a is placed on the upper surface of the adsorbent layer 15, and the upper end of the guide tube 20 is fitted into the center of the lower surface of the valve base 2, so that the container main body 1a is fitted with the punching metal 14a. Lid 1b
A canister is constructed by capping the two parts and caulking them together.

In the canister configured as described above, the fuel vapor generated in the fuel tank is transferred to the fuel vapor introduction pipe 3.
The pressure reaches the inside of the valve base 2, and when the pressure exceeds a predetermined value, the check ball 11 is opened. At this time, the check ball 12 is closed. Then, the fuel vapor first flows into the guide pipe 20 and the through hole 20b.
It enters the space 18 and spreads out, flows into the upper and lower adsorbent layers 15, especially the lower adsorbent layer, from the entire upper surface and is adsorbed.

When the internal combustion engine operates and a throttle valve (not shown) in the intake passage opens and the intake pipe negative pressure reaches a predetermined value, the check ball 13 of the air-fuel mixture outlet 7 communicating with the intake passage opens. Air is drawn into the adsorbent layer 15 through the air inlet 10a of the container body 1a. Then, the fuel vapor adsorbed in the layer is desorbed by this air, and the mixture is supplied to the intake passage through the mixture outlet 7 and the outlet pipe 4.

The check ball 12 opens when negative pressure is generated in the fuel tank, and functions to replenish air into the tank.

By the way, when the fuel vapor generated in the fuel tank during the desorption process flows into the canister, the guide pipe 20 and the air-fuel mixture outlet 7 are cut off, so the fuel vapor first passes through the guide pipe through the same route as above. 20 and then into the space 18. Then, it enters the upper layer of the adsorption layer 15 together with air, and then becomes a mixture and is led out from the mixture outlet 7. Therefore, the fuel vapor that has flowed into the canister is directly guided to the air-fuel mixture outlet 7 and supplied to the engine, and a situation where the air-fuel ratio becomes temporarily rich does not occur.

Note that the fuel vapor generated in the carburetor float chamber is also introduced from the other fuel vapor introduction pipe 30;
A solenoid valve (not shown) that closes when the ignition switch is turned on is provided in the middle of the conduit from the float chamber to the introduction pipe 30, so that fuel vapor does not go directly to the intake passage.

FIG. 4 shows a second embodiment, in which the fuel vapor guide pipe 20 is closed at its lower end,
A spacer 19 having punched metal plates 19a and 19b facing each other at a predetermined interval is fitted into the through hole 20b in the radial direction of the guide tube 20.
Around the guide tube 20, an adsorbent upper layer 15A and an adsorbent lower layer 15B are formed by winding activated carbon fiber papers 15a and 15b above and below a spacer 19, respectively, and the inside of the spacer 19 is connected to the above-mentioned space 1.
8 is formed.

FIG. 5 shows a third embodiment, in which the guide tube 20 has a rod-shaped body 20c whose lower part is thinner than the through hole 20b.
It is as follows. Thereby, the volume of the lower layer portion of the adsorbent layer 15 can be made larger than when the guide tube 20 is configured with tube bodies having the same diameter on the upper and lower sides.

6 and 7 show a fourth embodiment, which is characterized in that the space 18 is filled with an adsorbent. As the adsorbent, one with higher air permeability than the adsorbent layer 15 is used. For example, foamed activated carbon 15d having a three-dimensional cell structure as shown in FIG. 7 is preferably used.

In this embodiment, activated carbon fiber papers 15a and 15b are placed above and below the through hole 20b, respectively, around the guide tube 20 similar to the first embodiment (FIG. 1).
The adsorbent layer 15 is formed by winding and layering until they have the same diameter, filling the gap 18 between both layers with the foamed activated carbon 15d, and winding activated carbon fiber paper 15c around the outer periphery of both layers.

This embodiment has the advantage that the space 18 can also be used as an adsorbent layer. Note that since the foamed activated carbon filled in the space 18 has high air permeability, the foamed activated carbon filled in the space 18
Fuel vapor that has entered the space can easily spread throughout the space.

In the embodiments shown in FIGS. 1 and 3, punching metal plates 14 are provided on the upper and lower surfaces of the adsorbent layer 15.
a and 14b are provided, but if the upper end of the guide tube 20 and the valve base 2 are firmly connected and the activated carbon fiber paper is wound around the guide tube 20 so that it does not fall off, the result shown in FIGS. 5 and 6 can be obtained. There is no need for a punched metal plate as in the embodiment.

Although various embodiments have been shown above, combinations of these embodiments are also possible. Further, the fuel vapor guide pipe 20 can be integrally molded with the valve base 2, and the material may be either metal or resin as long as it has fuel vapor resistance. Also, the fuel vapor introduction pipe 30 may be removed if it is not necessary to introduce fuel vapor from the carburetor float chamber.

As described above, in the present invention, since the adsorbent layer is made of activated carbon fiber paper, the adsorbent is not pulverized by vibration or the like and has excellent durability. In addition, a fuel vapor guide pipe is provided inside the container, and a radially expanding space is provided within the adsorbent layer, allowing fuel vapor to enter the adsorption layer through the guide pipe and the space. Steam is prevented from being led directly to the engine. Furthermore, since the adsorbent layer is formed by using the guide tube and winding activated carbon fiber paper around it, various effects such as ease of formation of the adsorbent layer are obtained.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of the first embodiment of the present invention, FIGS. 2 and 3 are diagrams showing the manufacturing process of the adsorbent layer in the first embodiment, and FIG. 4 is the second embodiment. 5 is a longitudinal sectional view of the third embodiment, FIG. 6 is a longitudinal sectional view of the fourth embodiment, and FIG. 7 is an enlarged view of foamed activated carbon used in the fourth embodiment. be. 1... Container, 5... Fuel vapor inlet, 7... Mixture outlet, 10a... Air inlet, 15... Adsorbent layer, 15a, 15b, 15c... Activated carbon fiber paper, 15d... Foamed activated carbon, 18... adsorbent layer space, 20... fuel vapor guide pipe.

Claims (1)

[Claims] 1. A container having a fuel vapor inlet port communicating with a fuel evaporation source and a mixture outlet port communicating with an intake passage of an internal combustion engine on one end face, and an air outlet port on the other end face facing the above-mentioned one end face. , a fuel evaporation prevention device for a vehicle comprising: a fuel vapor adsorbent layer formed between the two end faces in the container; A fuel vapor guide pipe protruding toward the other end surface is provided, activated carbon fiber paper is wound and laminated around the fuel vapor guide pipe to form an adsorbent layer, and the adsorbent layer is disposed within the adsorbent layer. A fuel evaporator for a vehicle, characterized in that a space section is formed that traverses the fuel vapor guide pipe in a radial direction and divides the fuel vapor guide pipe into upper and lower layers, and the fuel vapor guide pipe is provided with a through hole that communicates the inside of the pipe with the space section. Prevention device.