JP3328929B2 - Canister - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a canister for introducing a mixed gas (hereinafter referred to as "vapor") of evaporated fuel and air evaporated in a fuel tank and temporarily adsorbing the evaporated fuel in the vapor. About.

[0002]

2. Description of the Related Art An example of a conventional canister is disclosed, for example, in Japanese Utility Model Laid-Open No. 3-54272. The canister disclosed here has an inflow port 101 and an outflow port 1 at the upper end of a case 100 as shown in FIGS.
02, an air port 103 is provided at the lower end, and an upper filter 104 and a lower filter 105 are arranged in a case 100, and an activated carbon layer 106 is formed between the two filters 104, 105. Also, the upper filter 10
An airtight annular body 107 is provided at 4, and is arranged so as to surround the opening of the inflow port 101.

[0003] By providing the annular body 107 in this manner,
The inflow port 101 is directly connected to the activated carbon layer 106 via the upper filter 104, and the inflow port 10
1 is introduced into the activated carbon layer 106 via the upper filter 104 in a region surrounded by the annular body 107, and the activated carbon adsorbs the evaporated fuel.

[0004]

On the other hand, at the time of purging,
The evaporative fuel is desorbed from the adsorbent by the air introduced from the atmospheric port 103, and the desorbed evaporative fuel passes through the annular region between the annular body 107 and the case 100 and flows out of the outflow port 102. . Therefore, the activated carbon layer 1
The flow rate of air per unit area flowing out from 06 increases as compared with the case where the annular body 107 is not provided, and the temperature of the activated carbon layer 106 is greatly reduced accordingly. As a result, the activated carbon is cooled, and the desorption efficiency of the evaporated fuel is deteriorated.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a new structure of a canister that can improve the desorption performance.

[0006]

SUMMARY OF THE INVENTION Accordingly, a canister according to the present invention comprises a canister containing an adsorbent layer for adsorbing evaporated fuel in a case. An inflow area where the fuel flows in and an outflow area where the evaporated fuel desorbed from the adsorbent layer flows out are defined by the partition member, and the area of the outflow area is smaller than the area of the inflow area. It is characterized by the following.

At the time of purging, the desorption of the evaporated fuel proceeds near the outflow area, and the adsorbent near the outflow area is cooled by the latent heat of vaporization at the time of desorption, but the area of the outflow area is smaller than that of the inflow area. By making it small, the influence of the heat of the outside air taken in through the case is more greatly affected, and a decrease in the desorption efficiency is suppressed.

Further, the outflow area in the canister of the present invention is an area surrounded by the case side wall and the partition member.

At the time of purging, an air flow is formed toward the outflow area through the adsorbent layer. By setting the area surrounded by the case and the partition member as the outflow area, the air flow is directed to the side of the case. You will pass through a nearby area. Therefore, desorption proceeds with the adsorbent located in the area close to the side of the case, and the adsorbent in this area is cooled.However, since the adsorbent is relatively close to the case itself, it takes in the heat of the outside air transmitted through the case. This facilitates the reduction of the separation efficiency.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described.
This will be described with reference to the accompanying drawings.

FIG. 1 shows a canister according to the embodiment. The case 1 of the canister is formed of a resin having high thermal conductivity, and steps 2 and 3 are formed on the upper and lower portions of the case 1 respectively. In the case 1, the upper filter 4 is arranged at a position corresponding to the step 2, and the step 3
The lower filter 5 is arranged at a position corresponding to the above, and between the upper filter 4 and the lower filter 5, an activated carbon layer 6 for adsorbing the evaporated fuel contained in the vapor is provided. A spring 7 is arranged at a lower portion in the case 1, and a lower portion of the case 1 is pressed against the lower filter 5 by applying a reaction force to the bottom of the case 1. Thereby, the activated carbon layer 6 is formed between the upper filter 4 positioned by the stepped portion 2 and the lower filter 5 pressed by the spring 7 in a state where the activated carbon is densely filled.

A space is formed between the case 1 and the upper filter 4, and this space is divided into two diffusion chambers 11 and 12 by a partition plate 8 formed integrally with the case 1. The upper filter 4 is in pressure contact with the partition plate 8 by the action of the spring 7, and the airtightness of the contact portion between the partition plate 8 and the upper filter 4 is ensured.

An inflow port 11 is connected to one diffusion chamber 21, and an outflow port 12 is connected to the other diffusion chamber 22. Further, a ventilation port 13 communicating with the atmosphere is provided on the opposite end side of the case 1.

Vapor flows from the inflow port 11, and the vapor that has flowed is diffused in the diffusion chamber 21, flows into the activated carbon layer 6 from the diffusion chamber 21 via the filter 4, and the fuel vapor in the vapor is removed from the activated carbon. Is adsorbed by At the time of purging, air is taken into the case 1 from the ventilation port 13, and the evaporated fuel is desorbed from the activated carbon by the air passing through the activated carbon layer 6. The evaporated fuel desorbed from the activated carbon in the activated carbon layer 6 reaches the diffusion chamber 22 from the activated carbon layer 6 via the filter 4 and flows out from the outflow port 12.

In FIG. 1, the diffusion chamber 21 on the inflow port 11 side is shown.
The region that flows into the activated carbon layer 6 from the above is referred to as an inflow region S1,
The area flowing out from the activated carbon layer 6 to the diffusion chamber 22 side is shown as an outflow area S2, and as shown in FIG.
The upper filter 4 is partitioned by the partition plate 8 so that the area 2 is smaller than the area of the inflow region S1.

Here, the operation of the partition plate 8 will be described.

First, FIG. 3 shows a state where there is no partition plate 8.
This will be described based on the schematic diagram of FIG. Vent port 13 during purge
The air flowing in through the activated carbon layer 6 goes to the outflow port 12, but at this time, the air flowing in the activated carbon layer 6 is more in the center of the activated carbon layer 6, and due to this effect, the air in the upper layer is The desorption of the evaporated fuel proceeds near the center, and the activated carbon in the area indicated by reference numeral 31 is cooled more by the latent heat of evaporation at that time. As the region 31 is cooled, the activated carbon in the peripheral region 32 is deprived of heat. Activated carbon becomes difficult to desorb as the temperature decreases, and the desorption efficiency decreases. In the vicinity of the center of the upper layer of the activated carbon layer 6, desorption proceeds in a relatively wide range, so that a gentle temperature gradient is formed from the center to the periphery of the activated carbon layer 6.

Next, when the partition plate 8 is provided as shown in FIGS. 4A and 4B, the air flowing into the activated carbon layer 6 from the ventilation port 13 at the time of purging passes only through the diffusion chamber 22 side. Therefore, the air flow rate per unit area passing through the outflow region S2 in the activated carbon layer 6 is larger than that in the case of FIG. For this reason, FIG.
As shown in FIGS. 3A and 3B, in the area 33 near the outflow port 12, the amount of the evaporative fuel released is larger than in the area 31 in FIG. 3, and the temperature drop of the activated carbon is larger than in the area 31 in FIG. Become. Further, due to this effect, the area 3 around the area 33
The activated carbon in 4 will also lose heat.

Here, the position of the partition plate 8 in the case 1 is moved in the left-right direction in FIG. 4A to change the ratio occupied by the two diffusion chambers 21 and 22. The result shown in the graph of FIG. The vertical axis of the graph represents the amount of desorption without the partition plate 8 shown in FIG. 3 as 1.0, and the horizontal axis represents the area ratio of the outflow region S2, specifically, the inflow region S1. And outflow area S
The area ratio of the inflow area S1 to the area sum of the area 2 and (the area ratio of the outflow area S2 = the area of the outflow area S2 / (the area of the inflow area S1 + the area of the outflow area S2)).

As can be seen from the graph of FIG. 5, the amount of desorption is large when the area ratio of the outflow region S2 is around 0.10 to 0.30, and is particularly large when the area ratio is around 0.20. It was found that, as a whole, by making the area ratio of the outflow region S2 smaller than 0.50, the desorption amount was improved as compared with the state without the partition plate 8.

This result can be considered as follows. As the ratio of the outflow area S2 decreases, the outflow area S2
As the air flow rate per unit area passing through increases, the center of the flow of the air flowing through the activated carbon layer 6 shifts further to the case 1 side, and a region near the side wall of the case 1 in the activated carbon layer 6 on the diffusion chamber 22 side. Will be cooled more. Therefore, the temperature gradient toward the periphery thereof from the central portion of the region of the diffusion chamber 22 side becomes a steep compared to the type of FIG. 3 in the state partition plate 8 is not, the outside air heat through the side wall of the case 1 It is considered that more is taken in and the amount of desorption is improved.

As shown in FIGS. 6A and 6B, an example in which the area of the outflow area S2 is divided so as to be smaller than the area of the inflow area S1, as shown in FIGS. It is also possible to use a partition plate 8a to partition the corner inside the case 1.

In addition, as shown in FIG.
Is cylindrical, the annular partition plate 8b is
Concentrically disposed within the inner partition plate 8b and the draining S1, it can be a region surrounded by the side wall of the partition plate 8b and the case 1 and the outflow region S2.

In any case, the region surrounded by the partition plate 8a or the partition plate 8b and the side wall of the case 1 is defined as an outflow region S2, whereby the flow of air flowing through the activated carbon layer 6 is directed to the side surface of the case 1. Since it is possible to concentrate on a near area, the same effect as in the above-described embodiment can be obtained.

The present invention can also be applied to canisters of the type shown in FIGS. 8 (a) and 8 (b). This canister has two ports, a port into which vapor flows in, and an inflow port 11 connected to a fuel tank and a refueling port 13 connected near a refueling port of the fuel tank. The space between 13 and the activated carbon layer 6 is 2
Divided by three partition plates 8c and 8d, and three diffusion chambers 2
1, 22, and 23 are formed. Also for this type of canister, the outflow area S2 is smaller than the total area of the inflow area S1 flowing into the activated carbon layer 6 from the diffusion chamber 21 and the inflow area S3 flowing into the activated carbon layer 6 from the diffusion chamber 23. What is necessary is just to specify so that an area may become small.

In the canister shown in FIGS. 8A and 8B, the lower end of the partition plate 8c penetrates through the filter 4 and protrudes into the activated carbon layer 6. With this configuration, The diffusion of the air passing through the activated carbon layer 6 is suppressed, and the region where the activated carbon is cooled is further limited to the case side, so that the desorption performance can be improved.

In the embodiment described above, the inflow port 1
Although the canister of the type in which the ventilation port 13 is provided on the side opposite to the outflow port 1 and the outflow port 12 is illustrated, the invention is also applicable to a canister having a structure in which the ventilation port 13 is folded back via a partition wall 40 as shown in FIG. It is possible to
In this case, by forming the partition wall 40 with a material having high thermal conductivity, the heat of the outside air flowing from the ventilation port 13 is reduced.
Since it is given to the activated carbon on the outflow port 12 side through 0, the same effect can be obtained from this point .

[0028]

As described above, the canister of the present invention has an inflow region in which fuel vapor flows into the adsorbent layer and an outflow region in which fuel vapor desorbed from the adsorbent layer flows out. The case was formed so as to be divided by the case side wall and the partition member, and the area of the outflow area was configured to be smaller than the area of the inflow area. As a result, the adsorbent in the area near the outflow port is cooled by the desorption, but by taking in much heat of the outside air through the case side wall , a decrease in the desorption efficiency is suppressed, and compared with the conventional canister. Desorption efficiency can be improved.

[0029]

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a canister according to an embodiment.

FIG. 2 is a plan view showing an inflow area and an outflow area.

FIG. 3 is a schematic diagram showing a temperature distribution on a longitudinal section of an activated carbon layer in a state where there is no partition plate.

4A is a schematic diagram showing a temperature distribution on a vertical section of the activated carbon layer in a state where a partition plate is provided, and FIG. 4B is a schematic diagram showing a temperature distribution on a horizontal section of an upper layer portion of the activated carbon layer in FIG. FIG.

FIG. 5 is a graph showing the relationship between the ratio of the diffusion chamber on the outflow port side and the amount of desorption.

FIG. 6A is a partial longitudinal sectional view showing a canister according to another embodiment, and FIG. 6B is a sectional view taken along line AA in FIG.

FIG. 7 is a plan view illustrating shapes of a case and a partition plate according to another embodiment.

FIG. 8A is a partial longitudinal sectional view showing a canister according to another embodiment, and FIG. 8B is a sectional view taken along line BB in FIG. 8A.

FIG. 9 is a longitudinal sectional view showing a canister according to another embodiment.

FIG. 10 is a longitudinal sectional view showing the structure of a conventional canister.

FIG. 11 is a perspective view showing the upper filter and the annular body in FIG. 10 taken out therefrom.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Case, 4 ... Upper filter, 5 ... Lower filter, 6
... activated carbon layer (adsorbent layer), 8, 8a, 8b, 8c ... partition plate (partition member), 11 ... inflow port, 12 ... outflow port, 13 ... vent port, S1 ... inflow area, S2 ... outflow area, S3 ... inflow area.

Claims (1)

(57) [Claims] 1. A canister in which an adsorbent layer for adsorbing evaporated fuel is accommodated in a case, wherein an inflow region in which the evaporated fuel flows into the adsorbent layer, and a desorbed region from the adsorbent layer, are provided in the case. An outflow area where the evaporated fuel flows out is defined by a partition member, the area of the outflow area is smaller than the area of the inflow area, and the outflow area is formed of the case side wall and the partition member. A canister characterized by being an area surrounded by: