JP2000335465A - Fuel tank breather device - Google Patents

Abstract

(57) [Summary] A breather device has a simple structure and is inexpensive. SOLUTION: Two one-way valves 3A and 3B are attached at intervals between breather tubes 2A and 2B extending from a fuel tank 1 and between the breather tubes 2B and 2C. The one-way valves 3A and 3B have a pair of joints 6 integrally projecting in opposite directions from the valve body 4, and the outer diameter of the joints 6 is inserted into each end of the breather tubes 2A, 2B and 2C. It is smaller than the inner diameter of the inner tube 20. Then, when the inner tube 20 is fitted inside the breather tubes 2A, 2B, 2C, and the joint portion 6 is further fitted inside the inner tube 20 and connected to the breather tubes 2A, 2B, 2C, the breather tube 2A , 2B, and 2C, a portion where the inner tube 20 is not fitted becomes a large-diameter portion 22 having a large passage cross-sectional area.
It liquefies due to a decrease in internal pressure and separates into gas and liquid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fuel tank breather device for a vehicle such as a motorcycle.

[0002]

2. Description of the Related Art Fuel tank breather devices are known.
For example, Japanese Patent Application Laid-Open No. 55-160674 discloses a fuel tank in which a sub-tank is provided and a breather tube is provided therein.

As shown in FIG. 4, a breather tube 2A extends from the upper portion of the fuel tank 1, and further includes one-way valves 3A and 3B and breather tubes 2B and 2C.
Are alternately connected so that they are connected in series, and the extended end of the breather tube 2C is connected to a catch tank (not shown).

The one-way valves 3A and 3B each have a valve body 4 at the center, and a valve body 5 which opens to the fuel tank 1 only when the internal pressure on the catch tank side is high. A pair of joints 6 protruding in opposite directions from both sides of 4 are provided integrally.

The joint portion 6 has a thin pipe shape having an outer diameter slightly larger than the inner diameter of the breather tubes 2A, 2B, 2C.
B and 2C, the one-way valve 3A is connected between the breather tubes 2A and 2B and the one-way valve 3B is connected between the breather tubes 2B and 2C, respectively. The inner diameters are substantially matched to form a communication passage having a substantially constant passage cross-sectional area as a whole.

[0006]

However, the above-mentioned Japanese Patent Application Laid-Open Publication No. Sho-A Sho-64 is not advantageous because it results in a complicated structure and an increase in the size and weight of the apparatus and a high price. In addition, it is required to reduce the size and weight so as to take up as little installation space as possible, and in this respect, the type shown in FIG. 4 is advantageous.

However, in the case of the structure shown in FIG. 4, the one-way valves 3A and 3B are made inexpensive by adopting a simple structure for the valve body 4, so that the fuel tank 1
There will be some fuel leakage from the side to the catch tank side. However, it is desired that such fuel leakage be reduced as much as possible in terms of saving fuel. In particular, it is required to prevent fuel leakage as much as possible in endurance racing vehicles. Then, this invention aims at realization of these requirements.

[0008]

According to a first aspect of the present invention, there is provided a fuel tank breather apparatus comprising: a breather tube extending from an upper portion of a fuel tank;
In a fuel tank breather device having an extended end connected to a catch tank and a one-way valve provided at an intermediate portion of the breather tube to prevent fuel from passing from the fuel tank side, the breather tube includes an outer tube and a length thereof. And an inner tube that is inserted so as to partially overlap the inside of the outer tube, and a portion of the outer tube where the inner tube is not provided is a large-diameter portion whose passage cross-sectional area partially increases. And

A second invention is characterized in that, in the first invention, the large-diameter portion is provided closer to the fuel tank than the one-way valve.

[0010]

According to the first aspect of the present invention, since the large diameter portion is provided at the intermediate portion of the breather tube, the fuel which is going to flow from the fuel tank side to the catch tank side in a vaporized state flows to the large diameter portion. When it enters, the passage cross-sectional area increases and the internal pressure decreases, so that it liquefies, separates from the air and gas and liquid, and easily returns to the fuel tank side again. Therefore, fuel flowing out of the breather tube can be reduced as much as possible.

Further, since the breather tube is composed of the outer tube and the inner tube inserted so as to partially overlap the lengthwise inside thereof, the portion of the outer tube where the inner tube is not provided is the large diameter. Can function as a unit. Therefore, a large diameter portion can be formed inside the breather tube while keeping the outer diameter of the breather tube unchanged, so that the breather device does not need to be increased in size and can be used as before even in an environment where the installation space is limited.

In addition, since the large-diameter portion is simply formed by partially changing the cross-sectional area of the passage of the breather tube using the inner tube, the large-diameter portion can be formed with a simple structure and is compact. Lightweight and inexpensive.

According to the second aspect of the present invention, since the large diameter portion is provided on the fuel tank side of the one-way valve, the fuel can be gas-liquid separated at the large diameter portion before flowing into the one-way valve.
Inexpensive one-way valves can be used as before.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment applied to a motorcycle for endurance racing will be described below with reference to the drawings. FIG. 1 is a partially cutaway view of a main part of a breather device according to the present embodiment, FIG. 2 is a diagram showing a fuel tank around a motorcycle to which the breather device is applied, and FIG. It is an enlarged cross section. In each of these figures, common parts to those in the conventional example of FIG.

First, in FIG. 2, a fuel tank 1 of a motorcycle configured for an endurance race has a refueling section 1 at an upper center.
0 is provided, and breather tube 2A,
2B and 2C extend forward of the vehicle body. The breather tube is divided into 2A, 2B, and 2C, each of which is made of a flexible and oil-resistant material such as vinyl.

One end of the breather tube 2A is connected to the fuel tank 1, and the extended end of the breather tube 2C is connected to a catch tank 12 supported on the outer surface of the main frame 11.
Connected to The cattank 12 is separated from the vaporized fuel by a trapping material provided therein and is absorbed and is open to the atmosphere. The breather tubes 2A, 2B,
The inside of the fuel tank 1 is communicated with the atmosphere via 2C.

Two one-way valves 3A and 3B are respectively mounted between the breather tubes 2A and 2B and between the breather tubes 2B and 2C, and the vaporized fuel in the fuel tank 1 flows out to the catch tank 12 side. Has been blocked. Reference numeral 13 in the drawing denotes an intake pipe of the fuel pressurizing device, 14 denotes a handle, 15 denotes an instrument panel, 16 denotes a headlight, 17 denotes a front fork, 18 denotes a radiator,
19 is a front wheel.

Next, details of the breather device will be described with reference to FIG. The breather tubes 2A, 2B,
2C and the one-way valves 3A and 3B have the same structure as the conventional example, but the outer diameter D1 of the joint 6 is smaller than the inner diameter D2 of the breather tubes 2A, 2B and 2C.
Accordingly, the inner diameter of the joint 6 is smaller than the inner diameter D2 of each of the breather tubes 2A, 2B, and 2C, and the outer peripheral surface of the joint 6 and the breather tubes 2A, 2A.
The inner tube 20 is interposed between each of the inner tubes 2B and 2C.

The inner tube 20 is a straight tubular member made of an appropriate material such as a metal or a synthetic resin, and is tightly fitted by being pushed into the breather tubes 2A, 2B, and 2C from the ends in advance so as to be tightly fitted. 2A, 2B,
The inside of the vicinity of each opening end of the 2C partially overlaps in the length direction, and the distal end position of the insertion portion substantially coincides with the distal end of the joint portion 6. In addition, breather tube 2
A, 2B and 2C correspond to the outer tube in the present invention.

The joint pipe 21 integrally provided above the fuel tank 1 and projecting upward and inserted into the breather tube 2A also has the same outer dimensions as the joint portion 6, and has a joint pipe 21 and the breather tube 2A. The inner tube 20 is interposed between the inner tube 20 and the inner surface of the inner tube. The outer shape of the inner tube 20 is a breather tube 2A,
The inner diameter of each of the joints 6B and 2C is approximately the same as or slightly smaller than the outer diameter of each of the joint portion 6 and the joint pipe 21. In addition, the length of the inner tube 20 is approximately the same as the length of the corresponding joint portion 6 and the joint pipe 21, and is a small component.

Only the breather tube 2A is provided between the distal ends of the joint portion 6 facing the joint pipe 21, and the inside thereof has no inner tube 20 and is a discontinuous portion of the inner tube 20. The inner tube 2
0 is inserted only into both ends of the breather tube 2A. As a result, the cross-sectional area of the passage at the discontinuous portion becomes D2, which is the inner diameter of the breather tubes 2A, 2B, and 2C, and the large-diameter portion where the cross-sectional area of the passage expands with respect to the inner diameters of the joint 6 and the joint pipe 21. 22A, 2
2B.

Furthermore, two one-way valves 3A, 3
B is also a discontinuous portion of the inner tube 20 where the inner tube 20 does not exist between the pair of joint portions 6 facing each other in the breather tube 2B, and this discontinuous portion is a large diameter portion 22B. That is, two large-diameter portions are also provided, and the large-diameter portion 22A is
The inside A and the large diameter portion 22B are formed in the breather tube 2B, respectively.

The one-way valves 3A and 3B have the same structure, and the detailed structure is shown in FIG. These one-way valves have a valve main body 4 having an outer diameter portion, and the valve main body 4 is made of a suitable thermoplastic synthetic resin, and is divided into two housings 4A joined in the axial direction of the joint 6. , 4B, and the joint between the two members is hermetically joined by ultrasonic welding to form a valve housing space 4C inside.
And a joint 6 is integrated with each of the housings 4A and 4B, and protrudes in opposite directions.

The housing 4A protrudes above the opening 30 of the joint portion 6 facing the valve body accommodating space 4C, and pushes the valve body 5 upward in the drawing at the tip thereof to bias the valve body 5 upward in the drawing. And an annular stopper wall 32 which surrounds the opening 30 and the elastic arm 31 and fits inside the housing 4B.

The housing 4B has a collar 33 screwed into a passage near the opening of the joint portion 6 facing the valve housing space 4C, so that the amount of protrusion of the collar 33 into the valve housing space 4C is adjustable. The collar 33 has an annular valve seat portion 34 that surrounds the open end of the collar 33 at intervals and protrudes into the valve body housing space 4C.

The valve element 5 has a substantially disk shape, and its disk portion 35
3 is seated on the valve seat portion 34, and the lower end portion is abuttable on the upper end of the stopper wall 32. A plurality of ventilation grooves 36 are provided in the outer peripheral portion of the disk portion 35 and are closed at the upper portion of the stopper wall 35 when the valve body 5 moves down.

In the center of the valve body 5, integral cylindrical portions 37, 38 projecting vertically in the figure are provided integrally, and a shaft hole 39 vertically penetrating through the axial center of the cylindrical portions 37, 38 is provided. Is formed. The cylindrical portion 37 is fitted to the collar 33 and is slidable in the vertical direction. The lower end of the cylindrical portion 38 is supported by the elastic arm portion 31.
Is closed at the lower end opening.

The valve element 5 opens and closes by the differential pressure between the catch tank side, which is the upper side of the figure, and the fuel tank side, which is lower when the internal pressure on the fuel tank side is equal to or higher than the catch tank side. The valve seat 34 is moved and seated on the valve seat 34, so that the valve is in a closed state in which communication between the catch tank side and the fuel tank side is cut off.

Conversely, when the internal pressure on the catch tank side increases, the valve body 5 is moved downward while deforming the elastic arm portion 31, and the valve is opened so that the catch tank side communicates with the fuel tank side via the communication groove 36. . Further, even if the downward movement is stopped by contacting the stopper wall 32 and the communication groove 36 is closed, the lower end opening of the shaft hole 39 is opened by the deformed elastic arm portion 31. Communication is maintained.

The urging force of the elastic arm 31 and the amount of protrusion of the stopper wall 32 and the valve seat 34 toward the valve element 5 are set so as to ensure the opening and closing operation of the valve. However, even in the valve closed state, the elastic arm 3 with respect to the seating portion of the disc portion 35 with respect to the valve seat 34 and the shaft hole 39.
As described above, it is impossible to avoid a slight amount of outflow of gas from the fuel tank side to the catch tank side through the closed portion.

Next, the operation of this embodiment will be described. In FIG. 1, the fuel vaporized from the fuel tank 1 side by heating or refueling of the fuel tank 1 is supplied to the joint pipe 2 together with air.
When flowing from 1 into the large diameter portion 22A of the breather tube 2A, since this portion has a large passage cross-sectional area,
The internal pressure drops sharply, and as a result, the vaporized fuel is liquefied and separated into air and gas, and is easily dropped into the breather tube 2A and returned to the fuel tank 1 side.

The remaining air and the vaporized fuel that cannot be completely separated enter the one-way valve 3A, where most of the fuel is prevented from flowing out to the catch tank side by the valve body 5, but it is still a part. Flows out of the gap between the valve element 5 and its seat portion. However, the fuel that has passed through the first one-way valve 3A also immediately enters the second large-diameter portion 22B, where it is similarly separated into gas and liquid. Since outflow to the side is prevented, outflow of fuel can be prevented as much as possible.

The fuel gas-liquid separated by the second large-diameter portion 22B drops onto the valve element 5 of the first one-way valve 3A, but the valve element 5 opens toward the fuel tank 1 side. This allows fuel to pass to the fuel tank 1 side, so that fuel can return to the fuel tank 1.

In addition, in a race-specification vehicle such as this embodiment, a special rapid refueling device is used to pressurize and refill fuel from the refueling unit 10, and a large amount of fuel is supplied from the fuel tank 1 during refueling. Although it flows out into the breather tube 2A, even in such a case, sufficient fuel recovery can be expected.

In addition, in the present embodiment, since the large-diameter portions 22A, 2B are formed by inserting the inner tubes 20 into the respective ends of the breather tubes 2A, 2B, 2C, the breather tubes 2A, 2B, 2C are formed. The large diameter portions 22A and 22B can be easily formed at low cost without using a special structure. Moreover, since the outer diameter side of the breather tubes 2A, 2B, 2C is not expanded, the conventional breather tubes 2A,
2B and 2C can be used as they are. In addition, since the inner tube 20 is merely inserted into the inside of each end of the breather tubes 2A, 2B, and 2C, the inner tube 20 can be made into a small component and can be easily attached.

Therefore, when the present invention is applied to a vehicle for endurance racing as in this embodiment, it can be used in the same manner as before even though the space for disposing the parts is large. In addition, by reducing fuel leakage as much as possible, it is possible to reduce the number of times of refueling and contribute to time-up. In particular, it is suitable for endurance races in which competition is long, and the effects of such fuel leakage are remarkable.

It should be noted that the present invention is not limited to the above-described embodiment, and various applications and modifications are possible. For example, the breather tubes 2A, 2B, and 2C are one-way valves 3A,
Even if the diameter of the housing 4A, 4B in the 3B is as large as the outer diameter of the housing 4A, the restriction of the space for disposing the parts can be made less likely. realizable. Further, the object to which the breather device is used is not limited to a race specification vehicle, and may be applied to a general vehicle.

[Brief description of the drawings]

FIG. 1 is a partial cutaway view of a main part of a breather device according to the present embodiment.

FIG. 2 is a diagram showing the periphery of a fuel tank of a motorcycle to which the breather device is applied.

FIG. 3 is an enlarged sectional view showing the structure of a valve body.

FIG. 4 is a diagram similar to FIG. 1 in a conventional example.

[Description of Signs] 1: fuel tank, 2: breather tube (outer tube), 3: one-way valve, 5: valve body, 6: joint, 20: inner tube, 21: joint pipe,
22: large diameter portion, 31: elastic arm portion, 34: valve seat

Claims (2)

[Claims] A breather tube extending from an upper portion of a fuel tank is provided, an extending end of the breather tube is connected to a catch tank, and a one-way valve is provided at an intermediate portion of the breather tube to prevent fuel from passing from the fuel tank side. In the fuel tank breather device described above, the breather tube is constituted by an outer tube and an inner tube inserted so as to partially overlap the lengthwise inside thereof, and a portion of the outer tube where the inner tube is not provided. A large-diameter portion having a partially enlarged passage cross-sectional area. 2. The fuel tank breather device according to claim 1, wherein the large diameter portion is provided closer to the fuel tank than the one-way valve.