JPH09256918A - Drain structure for canister - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress generation of a vapor odor in the vicinity of a drain tube, by providing a plurality of opening ports opening vapor in the drain tube, also separating each opening port from each other. SOLUTION: In a lower part of a canister 1, a drain tube 4 is provided, this drain tube 4 is divided into two branch pipes 5 from the halfway. Vapor opened from the drain tube 4 is respectively discharged into a drain box 7 from an end opening 5a of each branch pipe 5. Since diameters of both the end openings 5a are equal, vapor introduced into the drain tube 4 is made to flow out in a uniformly dispersed condition from each end opening 5a. Thus from the two end openings 5a separated by a prescribed distance L, respectively uniformly dispersed vapor is discharged, so as to decrease vapor concentration in the periphery of the end opening 5a as compared with in the case of opening concentrically from only one part, sensing of a vapor odor can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a canister for processing vapor (vaporized fuel) generated in a fuel tank of a vehicle, a ship, etc., and particularly to opening the vapor to the atmosphere via a drain tube. It is related to the drain structure for.

[0002]

2. Description of the Related Art A drain tube is connected to a canister used for a fuel tank, and the vapor passing through the canister is opened to the atmosphere through the drain tube. (See the official gazette). The vapor is opened to the atmosphere through the terminal opening of the drain tube, and the terminal opening is provided with a drain box for preventing the liquefied vapor from dropping on the road surface.

[0003]

However, in such a conventional technique, since the vapor passing through the canister is opened only from one end opening of the drain tube, the vicinity of the end opening is formed. There is a case where the concentration of the vapor becomes high and the vapor smells (gasoline smell). Therefore, conventionally, it has been necessary to increase the canister size and improve the vapor adsorption performance as a countermeasure.

The present invention has been made in view of such a conventional technique, and provides a drain structure of a canister capable of suppressing the generation of vapor odor without increasing the size of the canister.

[0005]

According to the first aspect of the present invention,
The drain tube is provided with a plurality of opening openings for opening the vapor, and the respective opening openings are separated from each other.

According to this structure, since the vapor that has passed through the canister is dispersed and opened from the plurality of opening openings of the drain tube, it is possible to suppress the production of vapor odor near the drain tube. Therefore, the canister can be downsized.

According to the second aspect of the present invention, the drain tube is branched into a plurality of portions from the middle, and the terminal opening of each branch tube is an open port.

According to this structure, since the drain tube is branched into a plurality of portions from the middle and the end openings of the respective branch pipes are opened, the diameters of the respective branch pipes are made equal to each other so that the branch pipes are opened from the respective open ports. The amount of vapor outflow can be made uniform. Therefore, it is advantageous in suppressing vapor odor.

According to the third aspect of the invention, one of the openings is a terminal opening of the drain tube, and the other opening is an opening formed in the middle of the drain tube.

According to this structure, one of the openings is a terminal opening of the drain tube, and the other opening is an opening formed in the middle of the drain tube. Therefore, there is no need to branch the drain tube, and the drain tube itself. Is easy to form.

According to a fourth aspect of the present invention, each opening has a drain box for receiving the liquefied vapor.

According to this structure, the liquefied vapor can be received by the drain box to prevent dripping onto the road surface.

According to a fifth aspect of the present invention, one opening is opened from the other opening so that the flow rates of vapor released from the one opening and the other opening become equal. The diameter of the mouth and the diameter of the other opening are set.

According to this construction, the so-called single-path drain tube has one opening port and the other opening port.
The amount of vapor release can be made equal. Therefore, it is advantageous in suppressing vapor odor.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below.

FIG. 1 shows a first embodiment of the present invention. Reference numeral 1 denotes a car canister, which is filled with an adsorbent such as activated carbon. A vapor introducing pipe 2 and a vapor discharging pipe 3 are provided on an upper portion of the canister 1, the vapor introducing pipe 2 is connected to an upper portion of a fuel tank (not shown), and the vapor discharging pipe 3 is an intake system for the engine. It is connected to the.

A drain tube 4 is provided below the canister 1.
Is provided. This drain tube 5 is 2 from the middle
It is divided into the branch pipes 5 of the book, and the terminal opening 5 of each branch pipe 5
“A” is an “open mouth”. Therefore, the terminal openings 5a are separated from each other by the distance L.

A one-way valve 6 is provided in the middle of the drain tube 4 to prevent the reverse flow of vapor. The terminal openings 5a of the respective branch pipes 5 have the same diameter and face the inside of the drain box 7, respectively. The drain box 7 is for preventing the liquefied vapor from dripping on the road surface at the terminal opening 5a, and may be provided with a dedicated part or a part of the vehicle body.

When the vapor generated in the fuel tank passes through the canister 1, the fuel component is adsorbed by the adsorbent inside. However, since 100% of the fuel component cannot be adsorbed, the vapor is released from the drain tube 4 to the atmosphere while leaving some fuel component. During operation, air is introduced into the canister 1 from an outside air inlet (not shown) due to the negative pressure of the engine intake system, and the air absorbs the fuel components adsorbed inside and is supplied to the engine side.

The vapor released from the drain tube 4 is discharged into the drain box 7 through the terminal opening 5a of each branch pipe 5. Since both end openings 5a have the same diameter, the vapor introduced into the drain tube 4 flows out from each end opening 5a in a uniformly dispersed state. In this way, since the evenly distributed vapors are discharged from the two terminal openings 5a that are separated by the predetermined distance L, the terminal openings are compared to the case where the openings are intensively opened from only one place as in the conventional case. The vapor concentration around 5a becomes low, and the smell of vapor is not felt.

2 and 3 show a second embodiment of the present invention. The same parts as those in the previous embodiment are designated by the same reference numerals, and the duplicate description will be omitted.

The drain tube 8 of this embodiment has a single tubular shape which is not branched in the middle. Therefore, the drain tube 8 of this embodiment is easier to form than the branched drain tube described above. An opening 8b is formed in the middle of the drain tube 8 in addition to the terminal opening 8a, and the terminal opening 8a and the opening 8b form an "opening opening" separated from each other by a distance L. . A drain box 9 is provided in each of the terminal opening 8a and the opening 8b.

Here, the diameter of the opening (orifice diameter) 8b is d ₁ , its cross-sectional area is a, and the flow velocity is v ₁ . Also,
The diameter of the terminal opening 8a (the inner diameter of the drain tube 8) is d ₂
The cross-sectional area is A and the flow velocity is v ₂ . Since it is preferable that the flow rates of vapor released from the openings 8b and the terminal openings 8a are equal from the viewpoint of the dispersibility of the vapor,
The diameters d ₁ and d ₂ of the opening 8b and the terminal opening 8a are set so that the vapor flow rate is the same (both are 3 liters / hour).

The relationship between the _two diameters d ₁ and d ₂ will be described below, and the numerical value (6.6 mm) of the diameter d ₂ of the terminal opening 8a will be described.
A method of obtaining the diameter d ₁ of the opening 8b when the distance L (300 mm) is known will be described.

First, for each vapor (fluid) flowing out from each terminal opening 8a and opening 8b, the following equation is established from Bernoulli's theorem. Here, ρ is the density, P ₂ is the pressure loss from the opening 8b to the terminal opening 8a, λ is the pipe friction coefficient, ν is the kinematic viscosity coefficient, μ is the viscosity coefficient, Re is the Reynolds number, and Q is the flow rate.

(Ρv ₁ ² ) / 2 = [(ρv ₂ ² ) / 2] + P ₂

(Ρv ₁ ² ) / 2 = [(ρv ₂ ² ) / 2] +
_{[Ρλ (L / d 2) v} 2 2/2 ]

(Ρv ₁ ² ) / 2 = [(ρv ₂ ² ) / 2] ×
[1 + λ (L / d ² )]

V ₁ ² / v ₂ ² = 1 + λ (L / d ² )

V ₁ / v ₂ = √ [1 + λ (L / d ² )] ... (1)

[0031] Here, in order to equalize the flow rate of the diameter d ₁ of the opening 8b and the diameter d ² of the terminal opening 8a, it holds continuity equation as follows.

Av ₁ = Av ₂

V ₁ / v ₂ = A / a = [(π / 4) d ₂ ² ] / [(π / 4) d ₁ ² ] = d ₂ ² / d ₁ ² (2)

From equations (1) and (2)

D ₂ ² / d ₁ ² = √ [1 + λ (L / d ² )]

(D ₂ ² / d ₁ ² ) ² = 1 + λ (L / d ² )

D ₂ ⁴ / d ₁ ⁴ = (d ₂ + λL) / d ₂

[D ₂ / (d ₂ + λL)] d ₂ ⁴ = d ₁ ⁴ (3)

From the equation (3), the relationship between d ₁ and d ₂ was found. As mentioned above, d ₂ is 6.6 mm and L is 300 mm
Therefore, if λ is obtained, d ₁ can be calculated.

When a fluid flows in a circular pipe having a smooth inner surface, the flow in the pipe forms a laminar flow, and the following formula is established.

Q = Av ₂ = [(π / 4) d ₂ ² ] v ₂

Then, v ₂ is obtained using this equation.

[0043] ^{3000cm 3 / 3600sec = (π /} 4)
× (0.66 cm) ² × v ₂

0.83 cm ³ /s=0.34×v ₂

V ₂ = 2.44 cm / sec = 0.0244 m / sec

Then, λ is obtained from ν and Re.

Ν = μ / ρ = 0.05 / 75.5 kg · s ² /
m ⁴ = 6.62 × 10 ^-4 m ² / s

Re = (v ₂ d ₂ ) / ν = (0.0244
× 6.6) / (6.62 × 10 ⁻⁴ ) = 243.38

Therefore, λ = 64 / Re = 64/243.
38 = 0.263

When the value of λ is put into the above equation (3), it becomes as follows and d ₁ is obtained.

[6.6 / (6.6 + 0.263 × 30)
0)] × 6.6 ⁴ = d ₁ ⁴

[0052] Therefore, for the ^{_{d 1 4 = 146.5, d 1}} =
It will be 3.5 mm. That is, in order to obtain the same vapor flow rate when the terminal opening 8a is 6.6 mm, the opening 8b is set to 3.
It needs to be 5 mm.

In the above first and second embodiments, an example in which two opening openings are provided separated from each other has been shown, but if they are separated from each other, three opening openings or more are provided. Is also good.

[0054]

According to the first aspect of the present invention, since the vapor that has passed through the canister is dispersed and opened from a plurality of opening ports of the drain tube, it is possible to suppress the generation of vapor odor near the drain tube. Therefore, the canister can be downsized.

According to the second aspect of the invention, since the drain tube is branched into a plurality of portions from the middle and the end openings of the respective branch pipes are open, the respective branch pipes have the same diameter. The amount of vapor flowing out from the opening can be made uniform. Therefore, it is advantageous in suppressing vapor odor.

According to the third aspect of the present invention, one of the openings is a terminal opening of the drain tube and the other opening is an opening formed in the middle of the drain tube, so that it is not necessary to branch the drain tube. It is easy to form the drain tube itself.

According to the fourth aspect of the invention, the liquefied vapor can be received by the drain box to prevent dripping onto the road surface.

According to the fifth aspect of the present invention, in the so-called single-path drain tube, it is possible to equalize the vapor opening amount between the one opening and the other opening. Therefore, it is advantageous in suppressing vapor odor.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a drain structure of a canister according to a first embodiment.

FIG. 2 is a schematic diagram showing a drain structure of a canister according to a second embodiment.

FIG. 3 is an enlarged cross-sectional view showing a drain tube of a second embodiment.

[Explanation of symbols]

 1 canister 2 vapor introduction pipe 3 vapor discharge pipe 4, 8 drain tube 5 branch pipe 5a terminal opening (opening port) 6 one-way valve 7, 9 drain box 8a terminal opening (opening port) 8b opening (opening port) L distance

Claims (5)

[Claims] 1. A drain structure of a canister for opening vapor that has passed through a canister to the atmosphere through a drain tube, wherein the drain tube is provided with a plurality of opening ports for opening the vapor, and the release ports are separated from each other. The drain structure of the canister, which is characterized in that 2. The canister drain structure according to claim 1, wherein the drain tube is branched into a plurality of portions from the middle, and the end opening of each branch pipe is an opening. 3. The canister drain structure according to claim 1, wherein one of the openings is a terminal opening of the drain tube, and the other opening is an opening formed in the middle of the drain tube. 4. The canister drain structure according to claim 1, wherein each opening has a drain box for receiving a liquefied vapor. 5. The diameter of one opening and the diameter of the other opening are adjusted from the distance between the one opening and the other opening so that the vapor flow rates released from the one opening and the other opening become equal. The canister drain structure according to claim 3, wherein a diameter of the opening is set.