JPH09112372A - Fuel tank breather device - Google Patents

Abstract

(57) Abstract: A breather device for breathing between a fuel tank for a vehicle and the outside thereof so as to maintain the inside of the fuel tank at atmospheric pressure. Even in the case of, the above-mentioned breathing action is surely performed and fuel is prevented from leaking to the outside. A breather section (15) capable of floating on a fuel level (L) is connected to an upper end of a breather tube (24) which is attached to a bottom wall in a fuel tank (T) and can flex freely, and the breather section (15) and the breather tube (24) are connected. The inside and the outside of the fuel tank T are communicated with each other via the, and the air and the fuel are separated by the gas-liquid separator 16 provided in the breather portion 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is mainly applied to vehicles and is used for containing a volatile fuel such as gasoline.
The present invention relates to a breather device for a fuel tank.

[0002]

2. Description of the Related Art As a conventional breather device for a vehicle fuel tank, A breather tank is provided at the top of the fuel tank, and a breather device is provided there (see Japanese Utility Model Publication No. 3-11054).

.. A tank cap provided on the upper wall of the fuel tank with a breather device (Japanese Patent Publication No. 62-603).
14).

[0004] A breather passage provided in the upper portion of the fuel tank is provided with a check valve to prevent the fuel from flowing out when the fuel tank is overturned (see Japanese Patent Laid-Open No. 50-116817).

[0005] A breather passage communicating between the inside and the outside of the fuel tank is provided with a gas permeable oil impermeable membrane so as to prevent the fuel from flowing out of the tank (JP-A-62-149).
Japanese Patent Laid-Open No. 580) and the like are known.

[0006]

By the way, in the above-mentioned prior art, since the breather device or the breather passage is integrally supported by the fuel tank, the breather device or the breather device is not supported when the fuel tank is tilted or laid sideways. There is a problem that the breather function may not work effectively when the breather passage is immersed below the liquid surface of the fuel.

The present invention has been made in view of the above circumstances. A breather function is always effective regardless of the position of the fuel tank, and the fuel can be prevented from flowing out. It is an object of the present invention to provide a breather device for a fuel tank.

[0008]

In order to achieve the above object, according to the invention of claim 1, an upper space provided in a closed fuel tank, the upper space in the fuel tank, and the outside of the fuel tank are provided. A breather device for a fuel tank, which is adapted to perform a breathing action between the breather tube and the breather tube, which is provided inside the fuel tank and communicates with the outside of the fuel tank, and a free end of the breather tube. And a breather section, wherein the breather tube is
The breather portion is formed of a flexible body that can freely bend in the fuel tank, and the breather portion can freely float on the liquid surface of the fuel in the fuel tank to separate the gas in the fuel tank from the fuel. Then, a gas-liquid separator for guiding to the breather tube is provided.

To achieve the above object, according to the invention of claim 2, in the invention of claim 1, the gas-liquid separator is formed of an air permeable film that allows air to permeate but does not allow fuel to permeate. A gas phase chamber partitioned from the inside of the fuel tank and a float that floats the gas phase chamber above the liquid surface of the fuel are provided, and the gas phase chamber is communicated with the breather tube.

In order to achieve the above object, according to the invention of claim 3, in the invention of claim 1,
The gas-liquid separator includes a gas-phase chamber having a labyrinth that separates the air in the fuel tank from the fuel, and a float that floats the gas-phase chamber above the liquid surface of the fuel, and the gas-phase chamber is the breather tube. It is characterized by being connected to.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

FIG. 1 is a side view of a motorcycle provided with the device of the present invention, FIG. 2 is a plan view of the motorcycle taken along the line 2 of FIG. 1, and FIG. 3 is a partially cutaway side view of a fuel tank. 4 is a cross-sectional view taken along line 4-4 of FIG. 3, FIG. 5 is the same cross-sectional view as FIG. 4 when the fuel tank is in the lateral direction, and FIG. 6 is a partially cutaway side view of the breather portion. FIG. 7 is a partial cross-sectional plan view taken along the line 7-7 of FIG.

1 and 2, the front fork Ff
The fuel tank T is mounted on the vehicle body frame F between the front wheel Wf supported by the vehicle and the rear wheel Wr supported by the rear fork Fr, and is attached to the front fork Ff at the front of the fuel tank T. A steering handle H is arranged, and a seat S is arranged behind the steering handle.
The body frame F is covered with the front cowl Cf and the rear cowl Cr.

Next, referring to FIGS. 3 and 4, the structure of the fuel tank T will be described. The tank body 1 has an upper wall 1 ₁
And the lower wall 1 ₂ are integrally joined to form a hermetically sealed structure, and front and rear mounting flanges 1 ₃ and 1 ₄ for the vehicle body frame F are integrally provided in front of and behind them.

[0015] The left and right central portion of the wall 1 ₁ on the tank body 1, the fuel supply tube 2 is provided. On the upper surface of this oil supply cylinder 2,
The fuel filler port 3 is opened, and the fuel filler port 3 is provided with a cap 4 that can be opened and closed. The cap 4 is composed of a ring-shaped mounting frame 5 and a cap main body 6 which is hinged to the hinge 5 so that it can be opened and closed in the vertical direction. The mounting frame 5 includes a plurality of mounting screws. It is fixed to the refueling cylinder 2 by 8. An annular packing 10 is provided on the lower surface of the cap body 6, and the packing 10 has an annular seating surface 2 ₁ formed on the refueling cylinder 2 when the cap body 1 is closed.
The oil supply cylinder 2 is seated on the base plate 1 and is fluid-tightly closed by the cap 4. A cylinder lock 11 is provided at the center of the cap body 6 as usual. This cylinder lock 11 is operated by inserting a key (not shown) into
The cap 4 can be locked to the refueling cylinder 2 by engaging the lower surface of the refueling cylinder 2.

As clearly shown in FIG. 4, an upper end of a drain pipe 12 is connected to one side of a bottom surface of the oil supply cylinder 2. The drain pipe 12 extends vertically through the tank body 1, and its lower end is is passed through and fixed to the lower wall 1 _2, it is opened to the atmosphere. Also in the bottom wall 1 ₂ of the tank body 1, a fuel cock C
Is connected to the mouthpiece 13, and the fuel cock C is connected to the fuel supply section of the engine through the supply tube 14.

In addition to the refueling cylinder 2, a breather device Br for performing a breathing action between the upper space A in the fuel tank T and the outside air is provided in the fuel tank T.

Next, the structure of the breather device Br will be described mainly with reference to FIGS. 3 to 7. The breather part 15, which constitutes the main part of the breather device Br, includes a gas-liquid separator 16 and a float 17. It is composed of The gas-liquid separator 16 is made of a fuel oil resistant synthetic resin material, and as shown clearly in FIGS. 6 and 7, a lid body 16 ₂ is welded to an upper opening surface of a separator body 16 _{1 having} a hollow cylindrical shape with a bottom. And the like, the separator main body 16 ₁ and the lid 16 ₂ are provided with window holes 18 and 19, respectively. Air permeable membranes 20 and 21 which are permeable to air but impermeable to fuel, respectively, are joined to the inner surfaces of the window holes 18 and 19, respectively.
8, 19 are closed. A gas phase chamber 22 is defined inside the gas-liquid separator 16.

The air permeable membranes 20 and 21 are
For example, it is made of a material having high fuel resistance, heat resistance and high strength such as polytetrafluoroethylene, nylon, and silicon rubber, and the particles of fuel such as gasoline do not penetrate due to its surface tension. Those with open holes are used.

A joint pipe 23 is integrally provided on the bottom wall of the gas-liquid separator 16, and the joint pipe 23 is
It extends downward from the bottom wall of the separator body 16 ₁ and opens to the outside. The float 1 formed in the shape of a hollow donut is formed on the lower surface of the gas-liquid separator 16.
7 is fixed so as to surround the joint pipe 23, and the gas-liquid separator 16 is configured to be able to freely float on the liquid surface of the fuel such as gasoline in the fuel tank T.

A flexible breather tube 24 made of a soft material such as synthetic resin and rubber having high fuel resistance is detachably connected to the joint pipe 23. The breather tube 24, the breather pipe 25 which is fixed to the fuel tank T vertically through in the bottom wall 1 ₂ of the fuel tank body 1 is inserted drop freely connected. As shown in FIGS. 3 and 4, the breather tube 24 has a fuel liquid level and a bottom wall 1 of the fuel tank T so that the gas-liquid separator 16 can freely float on the fuel level. _It has a dimension sufficiently longer than the maximum depth between _two .

Next, the operation of the first embodiment will be described. FIGS. 3 and 4 show the posture of the fuel tank T when the motorcycle is in a normal traveling state, and the breather device Br is shown in FIG. The breather part 15 floats on the fuel liquid level L, and most of it is exposed from the fuel liquid level L and is exposed in the upper space A in the upper part of the fuel tank T. Then, between the upper space A in the upper part of the fuel tank T and the outside air, a free breathing action is performed via the gas-liquid separator 16 and the breather tube 24, that is, gas of the fuel mixed gas in the tank T is Permeate through the air permeable membranes 20 and 21 and enter the gas phase chamber 22, from which the breather tube 24
The atmosphere outside the fuel tank T enters the gas phase chamber 22 through the breather tube 24 and flows from there into the upper space A, whereby the inside of the fuel tank T is kept at atmospheric pressure. .

The breather tube 24 can flex freely even if the fuel tank T is greatly vibrated, tilted back and forth, left and right, or laid sideways due to the motorcycle traveling on a sloping road, a bad road, or the like. Due to the bending, most of the gas-liquid separator 16 floating on the fuel liquid level L is exposed to the upper space A of the fuel tank T so that the breathing action is reliably performed and the inside of the fuel tank T is brought to the atmospheric pressure. In addition, the air permeable membranes 20 and 21 prevent the fuel from leaking to the outside.

FIG. 5 shows a case where the motorcycle is lying down and the fuel tank T is in a sideways posture.
In this case, even if the cap 4 is immersed in the fuel, the gas-liquid separator 16 floats on the fuel liquid surface L due to the flexible bending of the flexible breather tube 24, and most of it is It is exposed to the upper space A of the fuel tank T to ensure the above-mentioned breathing action, and moreover, the fuel does not leak outside.

Next, a second embodiment of the present invention will be described with reference to FIG.

FIG. 8 is a sectional view of the fuel tank. The same members as those in the first embodiment are designated by the same reference numerals. The second embodiment is a case of connecting the breather tube 24 to its proximal end to flex in a U-shape into the fuel supply tube 2 which is fixed to the upper wall 1 ₁ of the fuel tank T, the fuel supply tube 2 bottom wall A breather joint 30 is vertically fixed to the breather joint 30, and the base end of the breather tube 24 is connected to the lower end of the breather joint 30. The upper end of the breather joint 30 is formed on the ring-shaped mounting frame 5,
It is opened in the oil supply cylinder 2 communicating with the atmosphere through a labyrinth packing structure maze 31. In addition, this maze 31
Is for preventing intrusion of water and the like from the outside.

Next, a third embodiment of the present invention will be described with reference to FIG.

FIG. 9 is a sectional view of a part of the fuel tank. The same members as those in the first embodiment are designated by the same reference numerals. In the third embodiment, the breather tube 24 is bent in a U shape and its base end is connected to the cap body 6, and the cap body 6 is provided with a breather passage 35. The lower end of the breather passage 35 is projected downward from the lower surface of the cap body 6 and the base end of the breather tube 24 is connected thereto, and the upper end of the breather passage 35 is opened in the fuel cylinder 2. It is in communication with the atmosphere from here. Therefore, in this third embodiment, the gas phase chamber in the gas-liquid separator 16 is communicated with the atmosphere through the breather tube 24 and the cap body 6.

Next, a fourth embodiment of the present invention will be described with reference to FIG.

FIG. 10 is a vertical sectional view of the breather section,
The same members as those in the first embodiment are designated by the same reference numerals.
The structure of the breather portion of the fourth embodiment is different from that of the first embodiment, and a labyrinth structure maze is adopted as the gas-liquid separating means.

The breather unit 115 of the breather device Br '
Is composed of a gas-liquid separator 116 and a float 117. The gas-liquid separator 116 is configured by integrally capping a lid body 116 ₂ by welding or the like on the opening upper surface of a bottomed hollow cylindrical separator body 116 ₁ formed of a fuel oil resistant synthetic resin material, A plurality of drain ports 136 are opened at intervals in the circumferential direction at the bottom of the bottom wall of the separator body 116 _{1, and} the lid 11
6 The _2, a plurality of breather holes 137 concentrically is opened. In addition, the gas phase chamber 1 in the gas-liquid separator 116
A labyrinth packing function 138 having a labyrinth packing function is formed in 22. That is, in the gas phase chamber 122, a partition wall 139 suspended from the lid 116 ₂ and a bottom wall of the gas phase chamber 122 are formed. A zigzag-shaped labyrinth 138 and a central tube 140 extending upward from the center are formed, and the mixed gas of the fuel mist entering the gas phase chamber 122 through the breather hole 137 flows through the labyrinth 138 through an arrow in FIG. , The fuel mist is separated, and the gas is
It is discharged to the outside through a joint pipe 123 extending below the separator body 116. On the other hand, the fuel mist becomes droplets and is returned to the inside of the fuel tank T through the drain port 136.

On the bottom wall of the separator body 116, a hollow float 117 formed in a hollow donut shape as in the first embodiment is fixed so as to surround the joint pipe 123.

The gas-liquid separator 116 is constructed so that it can float above the liquid surface of the fuel such as gasoline in the fuel tank T, as in the first embodiment. The flexible breather tube 24 is detachably connected to the joint tube 123.

The breather section 115 in the fourth embodiment also has the same function as the breather section 15 in the first embodiment.

Although the first to fourth embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various embodiments are possible within the scope of the present invention. For example, in the above-described embodiment, the case where the breather device is applied to the fuel tank of the motorcycle has been described, but it goes without saying that the breather device can be applied to other vehicles as well, and instead of the material described above as the air permeable membrane. Other conventionally known air-permeable membranes can be used, and the labyrinth formed in the gas-liquid separator may have any structure as long as it has a labyrinth packing function.

[0036]

As described above, according to the invention described in each of the claims, even when the fuel tank is in any posture,
The breather portion is always floating above the liquid surface of the fuel so that the breathing action can be surely performed inside and outside the fuel tank, and the inside of the fuel tank can always be kept at atmospheric pressure.

The gas-liquid separator in the breather section can release the gas separated from the fuel inside the fuel tank through the breather tube to the outside of the fuel tank, thereby preventing the fuel from leaking to the outside. it can.

[Brief description of the drawings]

FIG. 1 is a side view of a motorcycle equipped with the device of the present invention.

FIG. 2 is a plan view of the motorcycle taken along the line 2 of FIG.

FIG. 3 is a partially cutaway side view of the fuel tank.

FIG. 4 is a sectional view taken along line 4-4 in FIG. 3;

FIG. 5 is the same sectional view as FIG. 4 when the fuel tank is turned sideways.

FIG. 6 is a partially cutaway side view of the breather section.

FIG. 7 is a partial cross-sectional plan view taken along line 7-7 of FIG.

FIG. 8 is a sectional view of a fuel tank showing a second embodiment of the present invention.

FIG. 9 is a partial sectional view of a fuel tank showing a third embodiment of the present invention.

FIG. 10 is a vertical sectional view of a breather portion showing a fourth embodiment of the present invention.

[Explanation of symbols]

 Breather section 115 Breather section 16 Gas-liquid separator 116 Gas-liquid separator 17 Float 117・ ・ ・ ・ Float 20 ・ ・ ・ ・ ・ ・ Air permeable membrane 21 ・ ・ ・ ・ ・ ・ Air permeable membrane 22 ・ ・ ・ ・ ・ ・ Gas phase chamber 122 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Gas phase chamber 24 ... Breather tube 138 ... Maze A ... Upper space L ... Fuel level T ... Fuel tank

Claims (3)

[Claims] 1. A fuel tank (T) is provided in the closed fuel tank,
In a breather device for a fuel tank, wherein a breathing action is performed between the upper space (A) in the fuel tank (T) and the outside of the fuel tank (T), the inside of the fuel tank (T) Provided in the fuel tank (T)
And a breather section (15; 115) connected to the free end of the breather tube (24). The breather tube (24) is connected to the free end of the breather tube (24). ) And a breather portion (1
5; 115) is the fuel level (L) in the fuel tank (T)
A gas-liquid separator (16; 116) which can float freely above and separates the gas in the fuel tank (T) from the fuel and guides it to the breather tube (24). The breather device for the fuel tank. 2. The gas-liquid separator (16) is an air permeable membrane (20, 20) which is permeable to air but impermeable to fuel.
21) A gas phase chamber (22) partitioned from the inside of the fuel tank (T) and a float (17) for suspending the gas phase chamber (22) above the fuel liquid level (L). (2
2. The breather device for a fuel tank according to claim 1, wherein 2) is communicated with the breather tube. 3. The maze (13) for separating the gas in the fuel tank (T) from the fuel.
8) with a gas phase chamber (122), and this gas phase chamber (12)
Float (11) for suspending 2) above the fuel level (L)
7. The breather device for a fuel tank according to claim 1, wherein the gas phase chamber (122) is communicated with the breather tube (24).