JPH05246367A - Fuel tank cap with breather mechanism - Google Patents

Abstract

(57) [Abstract] [Object] The present invention keeps the pressure in the fuel tank at atmospheric pressure at all times, and the fuel leaks even if the fuel tank removed during maintenance of the engine or the like is tilted or shaken. It is an object of the present invention to provide a fuel tank cap with a breather mechanism that does not cause strange noise during intake and exhaust. A fuel tank cap with a breather mechanism according to the present invention is a fuel tank cap with a breather mechanism having a breather passage communicating between a fuel tank and the atmosphere, and a breather valve mechanism provided between the breather passage and the fuel tank. The first breather valve, which normally keeps the breather valve mechanism normally communicating between the fuel tank and the atmosphere and shuts off the communication between the fuel tank and the atmosphere when the fuel tank is tilted by a predetermined angle or more, and the internal pressure of the fuel tank. When the value exceeds a predetermined value, a second breather valve that connects the fuel tank and the atmosphere is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel tank cap with a breather mechanism in a motorcycle or the like.

[0002]

2. Description of the Related Art Conventionally, most motorcycles have a method in which a carburetor and an engine are arranged below a fuel tank and the fuel in the fuel tank is supplied to the carburetor and the engine by using gravity. .. However, since gasoline for fuel has a high volatility, if the fuel tank exposed to high heat is sealed, the pressure in the tank will fluctuate drastically and the amount of fuel supplied to the engine will not be stable. In general, the type that supplies fuel to the engine from the fuel tank by utilizing gravity generally has a breather mechanism to keep the pressure in the fuel tank at atmospheric pressure. ..

FIG. 6 is a schematic view showing a simple structure of an example of the conventional breather mechanism as described above. As shown in the drawing, the structure connects a fuel tank 40 and a breather pipe 41 whose outer end is open to the atmosphere with a breather passage 42,
A mushroom-type exhaust breather valve 43 and an intake breather valve 44 are provided at the connecting portion between the breather passage 42 and the fuel tank 40.
When the internal pressure of the fuel tank 40 becomes higher than the atmospheric pressure, the pressure pushes up the umbrella portion of the breather valve 43 for exhaust, causing the air in the fuel tank 40 to escape to the atmosphere from the exhaust hole 45, and the fuel tank 40 When the internal pressure becomes lower than atmospheric pressure, the umbrella portion of the breather valve 44 for intake is pushed down to send the outside air into the fuel tank 40 from the intake hole 46,
The fuel tank 40 can always be kept at atmospheric pressure. In addition, the breather mechanism described above is generally formed integrally with the fuel tank cap.

[0004]

However, in the breather mechanism having the above-described structure, the umbrella portion of the mushroom-shaped breather valve 43, 44 is deformed according to the change in the internal pressure of the fuel tank 40, and the exhaust hole 45, the intake hole. Since the fuel tank 40 is sucked and exhausted intermittently by opening 46, when the internal pressure of the fuel tank 40 reaches a certain value, the umbrella part of the mushroom-type breather valves 43,44 vibrates suddenly. The interval between intake and exhaust may become extremely short, and when such a phenomenon occurs, the exhaust gas passing through the breather pipe 41, etc. by the umbrella portion of the mushroom-type breather valve 43,44 acts as a reed of the wind instrument. Or, the intake air is vibrated at a high frequency,
As a result, there is a problem that the exhaust gas or intake air that vibrates on the same principle as a wind instrument produces a sound resonates with the breather pipe 41 or the like to generate an odd sound. The phenomenon as described above often occurs when the motorcycle is stored outdoors at night and the like, and is unpleasant because it may be unpleasant and may reduce the commercialability of the motorcycle itself.

As a method for solving the above-mentioned problems, it is possible to solve the problems by providing the intake hole and the exhaust hole with no valve, and always communicating with the atmosphere.
In a motorcycle or the like that uses gravity to supply fuel from a fuel tank to an engine, etc., the carburetor, engine, etc. are installed under the fuel tank, so the fuel tank must be removed when maintaining them. If the worker carelessly tilts or shakes the fuel tank at that time, the fuel in the fuel tank may flow into the breather pipe or the like through the intake hole and the exhaust hole. Therefore, the present invention can maintain the pressure in the fuel tank at atmospheric pressure at all times, and even if the fuel tank removed during maintenance of the engine or the like is tilted or shaken, the fuel does not leak, and it does not occur during intake and exhaust. It is an object of the present invention to provide a fuel tank cap with a breather mechanism that does not generate noise.

[0006]

In order to achieve the above-mentioned object, a fuel tank cap with a breather mechanism according to the present invention is provided with a breather passage that connects the fuel tank and the atmosphere, and between the breather passage and the fuel tank. In a fuel tank cap with a breather mechanism having a breather valve mechanism provided, the breather valve mechanism is normally in continuous communication between the fuel tank and the atmosphere, and when the fuel tank is tilted by a predetermined angle or more, the fuel tank and the atmosphere And a second breather valve for shutting off the communication between the fuel tank and the atmosphere when the internal pressure of the fuel tank exceeds a predetermined value.

[0007]

In the fuel tank cap with the breather mechanism having the above-described structure, since the first breather valve always communicates between the fuel tank and the atmosphere, the inside of the fuel tank is always kept at the atmospheric pressure, and some external load or the like may be applied. When the pressure in the fuel tank becomes extremely high, the second breather valve is opened until the pressure in the fuel tank becomes equal to or lower than a predetermined value to improve exhaust efficiency and prevent the pressure in the fuel tank from fluctuating. In addition, the breather mechanism having the above-mentioned configuration, except when the operator inadvertently tilts or shakes the fuel tank removed by the operator during maintenance of the engine and the carburetor, etc.
Since the first breather valve always communicates the fuel tank with the atmosphere, the internal pressure of the fuel tank can be kept constant at all times without any strange noise.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A fuel tank cap with a breather mechanism according to the present invention will be described below with reference to the drawings. Figure 1
It is a side view of a motorcycle that employs a fuel tank cap with a breather mechanism of the present invention. Reference numeral 1 in the drawing denotes an engine, which is mounted on the frame 2 by an appropriate method. A carburetor 3 is provided above the engine, an air cleaner 4 is provided above the carburetor 3, and a fuel tank 5 is provided so as to cover the air cleaner 4. Further, a fuel tank cap 6 with a breather mechanism of the present invention is provided on the upper surface of the fuel tank 5, and a drain hose 7 is connected to the cap 6 through the inside of the fuel tank 5 to the outside. .. An outer end of the drain hose 7 is open to the atmosphere, and a canister 8 is connected between them. The above-mentioned canister 8 has a purifying agent such as activated carbon stored therein, and the purifying agent absorbs the fuel contained in the mixed gas exhausted from the fuel tank 5 through the fuel tank cap 6 at the time of exhaust. It is configured to exhaust only air into the atmosphere. Further, although not shown, the canister 8 has a flow path communicating with the carburetor 3, and when the fuel tank 5 is inhaled, the fuel absorbed in the above-mentioned purifying agent is partially absorbed by the drain hose 7. It is vaporized and supplied to the carburetor 3.

FIG. 2 is a schematic top view of the fuel tank cap 6 with the breather mechanism of the present invention described above. The outer frame 9 is firmly fixed to the cap mounting portion 10 of the fuel tank 5 by a suitable fixing member 11 such as a bolt. One end of the lid member 12 is pivotally supported by the outer frame 9 and is opened and closed by operating a key (not shown). The cap mounting portion 10 is formed integrally with the fuel tank 5. In the figure
Reference numerals 13 and 14 denote the first breather valve and the second breather valve of the breather mechanism configured below the lid member 12,
These are arranged between the fuel tank 5 and the breather passage 15. As shown in FIG. 3, one end of the breather passage 15 is connected to the drain hose 7, and the inside of the fuel tank 5 and the atmosphere are communicated with each other via the breather valves 13 and 14. In FIG. 3, reference numeral 16 denotes a fuel supply cock, and the fuel in the fuel tank 5 flows downward by gravity only when the cock 16 is opened and is supplied to the engine 1 via the carburetor 5.

FIG. 4 is a schematic AA of the fuel tank cap 6.
FIG. 6 is a cross-sectional view showing a state in which the lid member 12 is closed. In this state, the lid member 12 is fixed at this position by a lock mechanism (not shown). As shown in the drawing, the cap 6 is a substantially rectangular parallelepiped in which a first breather valve 13 and a second breather valve 14 are formed at the lower end of a lid member 12 in which a recessed opening that forms a breather passage 15 is formed. A mold piece having substantially the same shape as the lid member 12 when viewed from the upper surface having the concave portion 17.
18 is sealed with rubber or the like (no reference number) to be liquid-tightly fixed. The inner mold piece 19 in which the first breather valve 13 and the second breather valve 14 are formed in the recess 17 of the mold piece 18 described above.
Are sealed with rubber or the like (no reference numeral) so as to partition the two breather valves 13 and 14, and are fitted in a liquid-tight manner.

On the first breather valve 13 side (left side in FIG. 4) of the inner mold piece 19, the lower portion has a rectangular cross section and the upper portion has a circular cross section having a diameter smaller than a circle inscribed in the rectangle. A breather hole 20 formed in a tapered shape is formed between the rectangular portion and the circular portion, and the inner mold piece 19 is formed.
The breather hole described above when fitting the
The first breather valve 13 is formed by mounting a spherical valve member 21 of an appropriate material that is inscribed in the lower rectangular hole portion of 20. Since the first breather valve 13 having the above-described structure normally has a gap between the breather hole 20 and the spherical valve member 21, the inside of the fuel tank 5 and the breather passage 15 are communicated with each other, and the operator is required to perform maintenance. When the fuel tank 5 that was removed is tilted or shaken, the spherical valve member 21 causes the breather hole 20
Move to the tapered part of the breather hole
The upper circular cross section of 20 is closed.

The second breather valve 14 of the inner mold piece 19
The side (the right side in FIG. 4) is the first breather valve described above.
It is molded thinner from the 13 side, and a hole 23 for mounting the mushroom-shaped valve member 22 is formed near the center.
Further, exhaust holes 24 are formed on both sides of the hole 23 (in the left-right direction in FIG. 4), and the mushroom-shaped valve member 21 is formed so as to completely cover the exhaust hole 24 from above with the umbrella portion. Is configured to form the second breather valve 14. The umbrella portion of the mushroom-shaped valve member 22 is made of a material that is strong enough to open only when the internal pressure of the fuel tank 5 exceeds a certain value, and the internal pressure of the fuel tank 5 exceeds the certain value. Only at that time, the pressure raises the umbrella portion to open the exhaust hole 24 and improve the exhaust efficiency.

A hole 26 for communicating the hollow cylindrical intermediate chamber 25 with the first breather valve 13 is formed on the lower surface of the mold piece 19.
And a hole for communicating the intermediate chamber 25 with the second breather valve 14.
27 are drilled. The intermediate chamber 25 described above is integrally molded with the mold piece 18, and the lower end thereof is closed by a plate member 28. In addition, a plurality of slits 29 for connecting the intermediate chamber 25 and the fuel tank 5 are provided at the lower end of the outer surface of the hollow cylindrical intermediate chamber 25.
Has been drilled. Further, a pot-shaped outer frame member 30 is provided around the intermediate chamber 25 so as to surround it, and extends outwardly provided integrally with the upper end of the pot-shaped outer frame member 30. An annular elastic member 32 is attached to the annular flange portion 31.
And one end of the elastic member 32 is an annular fixing member 33.
Is firmly fixed to the mold piece 18. A spring 34 is provided between the bowl-shaped outer frame member 30 and the mold piece 18, and when the cap 6 is opened, the force of the spring 34 is released so that the outer frame member 30 is a plate member. When the cap 6 is closed and the space surrounded by the intermediate chamber 25 and the outer frame member 30 is closed, and the cap 6 is closed, the elastic member 32 is a convex edge of the cap mounting portion 10 shown by a phantom line in the drawing. The portion 35 is pressed from above to be deformed upward, and the bowl-shaped outer frame member 30 is lifted up against the force of the spring 34 to form a flow path 36 between the slit 29 and the fuel tank 5. Is configured.

FIG. 5 is a schematic BB sectional view of the fuel tank cap 6 showing the structure of the breather passage 15. As shown in the drawing, the breather passage 15 is formed by a downwardly-opening recess provided in the lid member 12 and the mold 18, one end of which is connected to the breather valves 13 and 14 and the other end of which is a cylindrical intake / exhaust hole.
37 is provided, and the intake / exhaust hole 37 and the drain hose 7 are liquid-tightly connected via a rubber seal member 38. Further, a weir 39 that suppresses the flow of the passage is integrally formed in a substantially central portion in the longitudinal direction of the breather passage 15, and the weir 39 and the cylindrical intake / exhaust hole 37 tilt the fuel tank. This prevents a small amount of fuel that has leaked before the first breather valve 13 is closed from flowing into the drain hose 7 when the first breather valve 13 is closed.

The operation of the above-configured fuel tank cap with a breather mechanism of the present invention will be described below.
When the internal pressure of the fuel tank 5 rises when the fuel tank 5 is closed, the mixed gas generated in the fuel tank 5 passes through the flow path 36 and slits 29.
→ Intermediate chamber 25 → Hole 26 → Breather hole 20 → Breather passage 15
→ Flows in the order of intake / exhaust holes 37, flows into the drain hose 7, and the fuel in the mixed gas is adsorbed by activated carbon or the like in the canister 8, and then is exhausted to the atmosphere from the outer end of the drain hose 7 to the fuel tank Reduce the internal pressure of. Further, when the internal pressure of the fuel tank 5 suddenly rises above a certain value, the mushroom type valve member 22 of the second breather valve 14 opens the exhaust hole 24 to enhance the exhaust efficiency.

When the internal pressure of the fuel tank 5 drops, air is sucked from the outer end of the drain hose 7 to vaporize the fuel adsorbed by the activated carbon or the like in the canister 8 and pass through a flow path (not shown) to form the carburetor 3. Intake and exhaust holes 37 while supplying
From the above, the air is supplied into the fuel tank 5 by following the reverse path when the internal pressure is increased, and the internal pressure of the fuel tank 5 is increased. In addition, during maintenance of the engine 1, the carburetor 3, etc., if the operator inadvertently tilts or shakes the removed fuel tank 5, the spherical valve member 21 of the first breather valve 13 causes the breather hole 20 to By moving to the tapered portion and closing the breather hole 20, the inside of the fuel tank 5 and the breather passage 15 are substantially closed.
Cut off communication with (ie the atmosphere).

In this embodiment, the first breather valve 13 includes a breather hole 20 having a tapered portion and a spherical valve member 21.
However, in the fuel tank cap with the breather mechanism of the present invention, it is closed when it has a certain inclination,
Any valve may be used as long as it is a valve that is normally open. Further, in the present embodiment, the second breather valve 14 is constituted by the mushroom type valve member 22 and the exhaust ports 24, 24 which are opened at a constant pressure. However, in the fuel tank cap with the breather mechanism of the present invention, Any type of valve may be used as long as it is a type of valve that is opened at the time of pressure. Furthermore, although the canister 8 is provided between the drain hoses 7 in this embodiment, the canister 8 is not essential. In the fuel tank cap with the breather mechanism of the present embodiment, the first breather valve 13 that is closed when it has a certain inclination and is normally opened.
Since the second breather valve 14 that connects the fuel tank 5 to the atmosphere communicates with the atmosphere only when the internal pressure of the fuel tank exceeds a predetermined value, the fuel tank 5 always communicates with the atmosphere, Occasionally, the valve does not produce strange noise, and intake and exhaust similar to the conventional breather function can be performed.

[0018]

The fuel tank cap with a breather mechanism of the present invention is normally equipped with a conventional breather valve mechanism in which two mushroom type check valves are used as intake and exhaust valves for intake and exhaust. Connecting the fuel tank and the atmosphere,
A first breather valve that shuts off communication between the fuel tank and the atmosphere when the fuel tank is tilted by a predetermined angle or more, and a second breather valve that communicates between the fuel tank and the atmosphere when the internal pressure of the fuel tank exceeds a predetermined value. Since the fuel tank and the atmosphere are normally communicated with each other, the effect that the internal pressure of the fuel tank can be maintained at atmospheric pressure without abnormal noise of the valve during intake and exhaust is provided. Play. Furthermore, in the fuel tank cap with the breather mechanism of the present invention, it is possible to prevent the occurrence of strange noise without lowering the intake / exhaust efficiency of the conventional breather mechanism by only partially modifying the conventional breather mechanism. The advantages are that it is easy to manufacture and the cost is low.

[Brief description of drawings]

FIG. 1 is a schematic side view of a motorcycle that employs a fuel tank cap with a breather mechanism of the present invention.

FIG. 2 is a schematic top view of a fuel tank cap with a breather mechanism of the present invention.

3 is a partially cutaway view of a fuel tank of the motorcycle shown in FIG.

FIG. 4 is a cross-sectional view taken along the line AA of the fuel tank cap with the breather mechanism shown in FIG.

5 is a cross-sectional view taken along line BB of the fuel tank cap with the breather mechanism shown in FIG.

FIG. 6 is a schematic view showing a configuration of a conventional breather mechanism.

[Explanation of symbols]

 5 Fuel tank 6 Fuel tank cap with breather mechanism 7 Drain hose 9 Outer frame 12 Lid member 13 First breather valve 14 Second breather valve 14 Breather passage 20 Breather hole 21 Spherical valve member 22 Mushroom type valve member 24 Exhaust hole 25 Intermediate chamber 29 Slit 37 Intake / exhaust hole

Claims (1)

[Claims] 1. A fuel tank cap with a breather mechanism, comprising: a breather passage communicating between a fuel tank and the atmosphere; and a breather valve mechanism provided between the breather passage and the fuel tank. A first breather valve that constantly connects the fuel tank with the atmosphere and shuts off communication between the fuel tank and the atmosphere when the fuel tank is tilted by a predetermined angle or more, and a fuel tank when the internal pressure of the fuel tank exceeds a predetermined value A fuel tank cap with a breather mechanism, characterized in that the fuel tank cap has a second breather valve that communicates with the atmosphere.