JPS6038507Y2 - fuel tank breather - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a fuel tank breather suitable for small general-purpose engines.

Conventionally, small two-stroke general-purpose engines are often used with working equipment mounted on them in an inclined state.

Therefore, various fuel tank breathers have been devised in order to eliminate fuel leakage from the fuel tank when the vehicle is tilted.

For example, as shown in FIG. 1, it is incorporated into a tank cap 3 that is screwed into a filler port 2 of a fuel tank 1.

The tank cap 3 is a resin molded product with a diameter of 1 to 2 r on the top wall.
An inverted cap-shaped holder 5 (rubber molded product) having a small rvn hole 4 is elastically fixed to the inner surface of the tank cap 3 at its outer periphery, and the tank cap 3 is attached to the threaded part 6 of the oil filler port 2. When screwed together, the outer peripheral edge of the holder 5 is held between the upper end surface of the oil filler port 2 and the inner surface of the tank cap 3, and serves as a backing.

The holder 5 has a small hole 7 with a diameter of 1 to 2 rrrtn in the center, and the space between the holder 5 and the tank cap 3 is filled with a filtration element 8 such as polyurethane foam, and when the fuel tank 1 is in a normal position. The holder 5 occupies a position spaced upward from the fuel oil level 9 as shown in the figure.

However, according to the above-mentioned conventional structure, (1) when the holder 5 and element 8 forming the breather are not immersed in fuel oil, air enters and exits (ventilation) from each small hole; Holder 5 when using
When the element 8 is immersed in fuel oil, fuel is blown out from the small hole 4 of the tank cap 3.

(2) If the engine is left tilted in the hot sun,
There is a problem in that even when the engine is not operated, the tank interior is pressurized due to an increase in the temperature inside the tank due to solar heat, an increase in the vapor pressure of the fuel, etc., and fuel comes out from the small hole 4 of the tank cap 3.

As a countermeasure for this, in order to give the breather the function of a check valve, a bowl-shaped part that protrudes downward is formed in the center of the comb plate.
It is conceivable to integrally form a downward lip portion with a slit at the lower end, but in that case, variations in molding dimensions and performance are likely to occur, and manufacturing costs will also increase.

Furthermore, it is difficult to mold the slit so that it is normally sealed, and furthermore, since the slit occupies a low position, the slit is likely to be submerged in fuel oil when used at an inclined angle.

The present invention is an attempt to solve the above problem, and has a small hole 4 at the upper end of a tank cap 3 that is attached to the filler port 2 of the fuel tank 1, and has an annular part with an inward U-shaped cross section at the upper end and a gasket. The annular portion of the bowl-shaped holder 11, which also serves as a bowl-shaped holder, holds the upper flat hard plate 12 and the lower membranous or film-like flat diaphragm 13 in close contact with each other vertically, and the outer peripheral surface of the annular portion is attached to the tank cap 3. An upper space 22 is formed in the tank cap 3 above the plate 12 by pressing against the inner circumferential surface of the intermediate portion of the holder 11, and a small hole 14 is provided at the lower end of the holder 11 that protrudes downward from the diaphragm 13 across a lower space 21. , a small hole 15 or notch is provided in the plate 12, and an air suction notch such as a slit 16 or a small hole is provided in the diaphragm 13 at a position laterally offset from the small hole 15 or notch in the plate 12 to allow air to flow into the tank. It is characterized by a check valve that only allows inflow, and one example is shown in Fig. 2.

In FIG. 2, the same reference numerals as those in FIG. 1 indicate corresponding parts.

The bowl-shaped holder 11 is a rubber molded product as in the past, and is in pressure contact with the inner surface of the tank cap 3 while holding the plate 12 and the diaphragm 13 at the annular part of the inward U-shaped cross section at the upper end. When screwed into the threaded portion 6, it is compressed between the tank cap 3 and the upper end surface of the oil filler port 2, and serves as a backing, and also pressurizes the outer peripheral edge of the joint surface of the plate 12 and diaphragm 13.

The holder 11 has a small hole 14 at its lower end.

The plate 12 is a flat hard disk made of sheet metal or resin,
It has a small hole 15 in the center.

The diaphragm 13 can be made of a film made of rubber or nylon, and has a thin thickness of about 0.2 m, for example, and its entire upper surface is in close contact with the lower surface of the plate 12 and tilted to a position slightly offset from the small hole 15. It has a slit 16.

The slit 16 extends parallel to the diametrical line O of the diaphragm 13, as shown in FIG.

During operation, the space 20 above the fuel oil level 9 is filled with fuel vapor, and due to the vibration of the fuel tank and tilted operation, particulate fuel adheres to the lower surface of the diaphragm 13 through the small hole 14 and the lower space 21 above it. , a part of it passes through the slit 16 and wets the joint surface of the plate 12 and diaphragm 13,
Due to the viscosity of this fuel, the plate 12 and diaphragm 13
completely seals the lower space 21.

Therefore, even if the oil surface 9 violently ripples during operation and many oil droplets collide with the diaphragm 13, these fuels will not flow through the plate 1.
2 and the diaphragm 13 are cut off.

That is, in the state shown in FIG. 2, the diaphragm 13 comes into close contact with the plate 12 due to the rigidity of the diaphragm 13 and the viscosity of the fuel, and no fuel leaks to the outside of the cap.

As the operation continues, the fuel oil level 9 decreases and the volume of the space 20 increases, and when the pressure decreases, the slit is closed due to negative pressure acting on the lower surface of the diaphragm 13 and atmospheric pressure acting on the upper surface of the diaphragm 13 through the small hole 15. 16 is opened as shown in FIG. 4, and air flows from the atmospheric pressure side outside the tank cap 3 through the upper space 22 into the tank (negative pressure side) to perform ventilation.

After a certain amount of air has flowed in, the slit 16 is closed as shown in FIG.

As explained above, according to the present invention, a check valve that only allows air to flow into the tank is formed by the action of the plate 12 and the slitted diaphragm 13 that is in close contact with the lower surface of the plate 12. When the tank is left in the hot sun, the diaphragm 13 comes into close contact with the plate 12 due to the gravity of the fuel and the pressure inside the tank, thereby closing the check valve, thereby reliably preventing fuel from blowing out.

Moreover, since the check valve is formed by the combination of the flat hard plate 12 on the upper side and the flat diaphragm 13 on the lower side, the structure is simple and easy to manufacture, and variations in size and check valve function can be made possible. The performance as a breather is stabilized.

Since the slit 16 occupies a position separated by light above the fuel oil level 9, it is highly effective in preventing wetness even when used at an inclined angle, and also from this surface.

In the present invention, a lower space 21 is formed below the diaphragm 13 in cooperation with the holder 11, and a small hole 14 is provided at the downwardly projecting lower end of the holder 11, so that the fuel oil level 9 is violently undulated. Even in such a case, it is difficult for the fuel droplets to reach the slit 16, and even if some fuel droplets enter the lower space 21 through the small hole 14, the fuel will not reach the slit 16.
6, it is returned to the fuel tank 1 through the small hole 14, and together with the fact that the plate 12 and the diaphragm 13 form a check valve that only allows air to flow into the tank, Fuel leakage can be prevented as much as possible.

Even if some of the fuel reaches the slit 16, the diaphragm 1
3 is in close contact with the plate 12, the fuel film formed between them serves as a seal, improving the effectiveness of the check valve.

Even if fuel leaks from the small hole 15 into the upper space 22 above the plate 12, the upper space 22 is created between the plate 12 and the tank cap 3, so the fuel will leak out through the small hole 4. There is no risk of leakage, ensuring double safety.

The plate 12 and the diaphragm 13 are held in close contact with the annular portion of the outer periphery of the rubber molded product holder 11, which also serves as a packing, and the holder 11 has a structure in which its outer periphery is pressed against the inner periphery of the tank cap 3. plate 1
2 and the diaphragm 13 can be easily attached, and there is an advantage that a state of close contact between the two can be reliably obtained.

Holder 1 that holds plate 12 and tire flam 13
1 is attached to the tank cap 3, the slit 16 can be sufficiently separated upward from the fuel oil level 9.

5 to 7 are drawings showing other modified examples, with the upper side being a longitudinal sectional view and the lower side being a bottom view.

The diaphragm 13 in FIG. 5 has a small hole 23 at a position offset from the small hole 15. The diaphragm 13 shown in FIG.

The diaphragm 13 in FIG. 6 has a C-shaped notch 2 when viewed from the bottom.
6, thereby closing the small hole 15 from below.
7 is made.

In this case as well, there is an advantage that the operation of the lip 27 is sensitive.

FIG. 7 shows another embodiment in which the diaphragm 13 has a small hole 2 in the center.
3, and the plate 12 has a cutout hole 28, which has the advantage of being sensitive to small pressure differences, similar to the one shown in FIG.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view showing the conventional structure, Fig. 2 is a longitudinal sectional view of the breather according to the present invention, Fig. 3 is a partial cross-sectional view taken along the line ■-■ of Fig. 2, and Fig. 4 is a longitudinal sectional view of the breather according to the present invention. Diagram of breather operation,
5 to 7 are drawings for showing other modified examples, with the upper side being a longitudinal sectional view and the lower side being a bottom view. 1...Fuel tank, 12...Plate, 13...Diaphragm, 15...Small L 16-------Slot, 20・・・・・・
·space.

Claims (1)

[Scope of utility model registration request] A small hole 4 is provided at the upper end of the tank cap 3 that is attached to the filler port 2 of the fuel tank 1, and the upper end is flat with the annular part of the bowl-shaped holder 11, which has an annular part with an inward U-shaped cross section at the upper end and also serves as a gasket. The hard plate 12 and the lower membrane-like or film-like flat diaphragm 13 are held in close contact with each other vertically, and the outer peripheral surface of the annular portion is held by the tank cap 3.
An upper space 22 is formed in the tank cap 3 above the plate 12 by pressing against the inner circumferential surface of the intermediate part of the holder 11, and a small hole 14 is provided at the lower end of the holder 11 which projects downward from the diaphragm 13 across the lower space 21. Small hole 15 in plate 12
Alternatively, a notch is provided, and the slit 1 is placed in the small hole 15 of the plate 12 or in the diaphragm 13 at a position laterally offset from the notch.
6 or a fuel tank breather-0 characterized in that it has an air suction cutout such as a small hole to form a check valve that only allows air to flow into the tank.