JPH11254980A - Valve for preventing liquid fuel from flowing out - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further restrain a liquid fuel from entering into an opening of an evaporator by enhancing the responsiveness of a float valve in such a case that the surface of the liquid fuel ruffles. SOLUTION: A valve for preventing a liquid fuel from flowing out, is composed of a housing having an opening 13 for an evaporator, a float valve 2 floating in the fuel so as to be moved up and down in order to open and close the opening 13, and a support member 3 regulating the downward movement of the float valve 2, the support member 3 being vertically movable relative to the housing. When splashing and waving of the fuel impinges upon the support member 3, the support member 3 is abruptly floated up due to impinging energy, and accordingly, the float valve 2 ascends in acceleration so as to instantly close the opening 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in the structure of a liquid fuel outflow prevention valve provided in a fuel tank or the like of an automobile, and more particularly to a liquid fuel outflow prevention valve capable of further preventing the outflow of liquid fuel to an evaporation circuit. .

[0002]

2. Description of the Related Art A vaporized fuel circulation system called an evaporation circuit is provided near a fuel tank of an automobile.
This evaporative circuit is for preventing a rise in the internal pressure of the fuel tank due to a rise in the vapor pressure by guiding the vaporized fuel from the fuel tank to an external canister, adsorbing it on activated carbon or the like, and temporarily storing it. The canister is connected to the engine. The canister releases the vaporized fuel from the activated carbon by the negative pressure of the intake air of the engine and mixes it into the air-fuel mixture to use the fuel again.

In this evaporation circuit, an opening called an evaporation opening is formed in the fuel tank. The evaporator opening is generally formed at the top of the fuel tank to prevent the liquid fuel from flowing into the evaporator circuit. However, the liquid fuel may flow into the evaporator opening due to the vertical movement of the fuel liquid level. If the liquid fuel flows into the canister, the adsorption on the activated carbon impairs the normal adsorption function of the vaporized fuel.

Therefore, conventionally, the evaporator opening is shown in FIGS.
The liquid fuel outflow prevention valve shown in FIG. The liquid fuel outflow prevention valve includes a housing 102 provided at an upper portion of a fuel tank 100 and having an evaporation opening 101, and a housing 102 which is housed in the housing 102, floats on the fuel, and moves up and down by the vertical movement of the liquid surface. Float valve 103 that opens and closes and float valve 1 held by housing 102
It comprises a support member 104 for supporting the lower surface of 03 and restricting its lowering, and a spring 105 interposed between the float valve 103 and the support member 104 to urge the float valve 103 upward.

In this liquid fuel outflow prevention valve, for example, FIG.
When the fuel liquid level is below the housing 102 as shown in FIG.
Is overwhelmed by the biasing force on the support member 104, and the evaporation opening 101 is opened. Therefore, when the internal pressure in the fuel tank 100 increases due to an increase in vapor pressure due to an increase in temperature, etc., the vaporized fuel is introduced into the evaporative circuit from the evaporative opening 101, so that the internal pressure of the fuel tank 100 can be adjusted.

When the fuel level rises, as shown in FIG. 5, the float valve 103 floats by the buoyancy from the fuel and the urging force of the spring 105, and the evaporation opening 101 is closed by the float valve 103. Therefore, the liquid fuel is prevented from flowing into the evaporation circuit from the evaporation opening 101.

[0007]

However, there are cases where the liquid level in the fuel tank undulates depending on the road surface conditions during traveling. The liquid fuel may splatter due to the collision of waves on the liquid surface or the collision with the wall surface.
In such a case, even when the fuel level is located below the float valve 103 as shown in FIG. 6, the fuel droplets 200 and the like may enter from the evaporation opening 101 in some cases.

If the float valve 103 is made lighter or the biasing force of the spring 105 is made larger, the responsiveness of the float valve 103 is improved, so that the above-mentioned problems can be prevented to some extent. However, the liquid fuel is
The evaporator opening 101 is closed even though it has not reached
There is a limit to such adjustment, as the evaporator opening 101 does not open even when the fuel level drops.

The present invention has been made in view of the above circumstances, and the opening and closing ability of a float valve in a normal state is equal to that of a conventional float valve. It is an object of the present invention to improve responsiveness and to further suppress entry of liquid fuel into an evaporator opening.

[0010]

The liquid fuel outflow prevention valve of the present invention, which solves the above-mentioned problems, is characterized in that a housing having an evaporative opening provided at an upper portion of a fuel tank and through which vaporized fuel passes, and a housing accommodated in the housing. A float valve that floats on the fuel and moves up and down by the vertical movement of the fuel level to open and close the evaporator opening, and a support member that is held by the housing and regulates the lowering of the float valve. In the housing so as to be relatively movable at least in the vertical direction.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a liquid fuel outflow prevention valve according to the present invention, when a fuel level is normally lower and a float valve cannot be lifted in a normal position, the float valve is supported by its supporting member by its own weight as in the prior art. The evaporative opening is open. Therefore, the vaporized fuel in the fuel tank flows into the evaporative circuit from the evaporative opening, and the internal pressure of the fuel tank is adjusted.

Then, when the fuel level rises and the float valve floats, the float valve is pressed against the evaporative opening by the buoyancy and the evaporative opening is closed. This prevents the liquid fuel from entering the evaporative opening and entering the evaporative circuit. When the liquid level in the fuel tank undulates, and the liquid fuel splashes due to the collision of waves on the liquid level or the wall, if the splash or wave collides with the support member, it is supported by the collision energy. The member rises rapidly. Therefore, the float valve also rises at an accelerated rate, and the momentum closes the evaporative opening instantaneously, thereby preventing the liquid fuel from entering the evaporative opening. Further, the float valve is also raised by raising the support member, and the distance between the float valve and the evaporation opening is reduced. As a result, the float valve floats and closes the evaporator opening even with a slight change in the liquid level, so that the responsiveness of the float valve is improved.

The housing may be integrated with the fuel tank or may be separate from the fuel tank. The position of the evaporative opening is generally the uppermost part of the housing, but is not particularly limited as long as the float valve can close the evaporative opening by buoyancy. Further, the shape of the evaporation opening may be any shape as long as the float valve can be closed. The float valve can be made of the same material and the same shape as the conventional one. In addition, the floating valve may be configured to float only by the difference between the apparent specific gravity of the float valve and the specific gravity of the liquid fuel, or the urging force of the urging means such as a spring may be used as an assist of the buoyancy.

The distance between the float valve and the evaporation opening is
With the support member descending to the maximum and the float valve being supported by the support member, the diameter can be reduced to about 4 mm or less, which is the same as that of the related art. It is desirable to use a support member having a specific gravity equal to or slightly larger than that of the liquid fuel. As a result, even if the fuel level rises in normal times, the support member is at the lowered position, so that the distance between the float valve and the evaporator opening can be made equal to the conventional one, and the liquid fuel does not reach the evaporator opening. This prevents a problem that the evaporative opening is closed.

If the specific gravity of the support member is too small, the fuel level rises and rises up to the support member when the fuel level rises in normal times. Therefore, the distance between the float valve and the evaporative opening is reduced, and the liquid fuel reaches the evaporative opening. In some cases, the evaporator opening may be closed even though it is not performed. If the specific gravity of the support member is too large compared to the liquid fuel, it is difficult to ascend and move when a splash or a wave collides, and in such a case, the liquid fuel enters the evaporation opening. Therefore, when the fuel is, for example, gasoline, the apparent specific gravity of the supporting member is desirably in the range of 0.8 to 1.5.

The support member may be provided with, for example, a flange portion to make it easier to receive the force from the rippling liquid fuel, but in this case, it may receive the opposite downward force from the rippling liquid fuel. This is not preferable because the acceleration of the float valve is prevented from rising. Therefore, it is preferable that the surface of the support member that receives the force from the liquid fuel has a size not exceeding the lower area of the housing. As a result, the surface receiving the downward force is not exposed, so that only the upward force is transmitted to the support member.

[0017]

The present invention will be described below in detail with reference to examples. FIG. 1 shows a liquid fuel outflow prevention valve according to one embodiment of the present invention. This liquid fuel leakage prevention valve is a housing provided integrally with a gasoline tank 1 in a gasoline tank of an automobile.
10 and float valve 2 housed in housing 10
And a support member 3 supporting the lower end surface of the float valve 2 and held by the housing 10, and a spring 4 interposed between the float valve 2 and the support member 3.

The housing 10 has a cylindrical side wall 11 having a rectangular cross section.
And an upper wall 12, and an evaporation opening 13 communicating with an evaporation circuit (not shown) is formed in the upper wall 12. Further, a pair of long holes 14, 14 facing each other and extending in the vertical direction are formed in the side wall 11. The float valve 2 has a convex portion 20 on the upper surface and a concave portion 21 on the lower surface. The projection 20 has an inverted truncated cone shape, and has a shape that closes the evaporation opening 13 when its tip enters the evaporation opening 13. The spring 4 is housed in the recess 21. The float valve 2 is made of nylon, polyacetal, or the like, and is formed by the recess 21 and the spring 4 so that the apparent specific gravity is smaller than that of gasoline.

The support member 3 comprises a plate-shaped portion 30 having a plurality of through holes 31 and a pair of legs 32, 32 projecting from the plate-shaped portion 30 so as to face each other. Are formed with claw portions 33, 33 each having an engagement surface 34 protruding inward. The claws 33, 33 are respectively formed by the elongated holes 14,
By engaging with 14, the plate-shaped portion 30 functions as the bottom of the housing 10.

The support member 3 is made of nylon,
Both the apparent specific gravity and the true specific gravity are 1.05, and are configured to be slightly higher than the specific gravity of gasoline. Here, the length from the engagement surface 34 of the claw portion 33 to the plate-shaped portion 30 is
The support member 3 is formed to be 2 mm longer than the length from the lower end surface to the lower end surface of the side wall 11, and the claw portions 33, 33 move in the elongated holes 14, 14 so that the support member 3 moves up and down by a distance of 2 mm with respect to the housing 10. Relative movement is possible.

The spring 4 is housed in the concave portion 21 of the float valve 2, and both ends of the spring 4 are respectively held in contact with the concave portion 21 and the plate-shaped portion 30 of the support member 3, so that an urging force is stored. Held in state. However, the biasing force is smaller than the weight of the float valve 2 and the float valve 2 in the atmosphere and gasoline vapor.
Presses the spring 4 by its own weight, and the lower end surface becomes the plate-shaped portion 30.
Is in contact with

In the liquid fuel outflow prevention valve of the present embodiment configured as described above, when the gasoline liquid level is below the support member 3 and in a quiet normal state (FIG. 1), the float valve 2 and the spring 4 The own weight of the support member 3 and the own weight of the support member 3 itself overcome the urging force of the spring 4, whereby the support member 3 descends, and the locking surface 34 of the claw portions 33, 33 is elongated.
Is in contact with the lower end surface of the. Since the supporting member 3 is pressed downward by the urging force of the spring 4, a gap 15 of 2 mm is formed between the tip of the side wall 11 of the housing 10 and the supporting member 3.

In this state, since the distance between the tip of the convex portion 20 of the float valve 2 and the evaporative opening 13 is 4 mm and the evaporative opening 13 is open, gasoline vapor flows freely from the evaporative opening 13 into an evaporative circuit (not shown). This prevents the internal pressure in the gasoline tank 1 from increasing. And when the gasoline level rises, the liquid gasoline
The buoyancy is gradually applied to the float valve 2 by entering the housing 10 from the above. When the gasoline liquid level exceeds a predetermined height, the float valve 2 floats due to the buoyancy and the urging force of the spring 4, and as shown in FIG.
And the evaporation opening 13 is closed. This prevents liquid gasoline from entering the evaporation opening 13. Also,
Since the support member 3 is pressed downward by the urging force of the spring 4, a gap 15 of 2 mm is formed between the tip of the side wall 11 of the housing 10 and the support member 3.

On the other hand, when the vehicle is traveling on a road with large irregularities, the gasoline level is greatly wavy, and gasoline droplets fly in the gasoline tank 1.
Even if the liquid level is located below the position where the liquid floats, there is a risk that liquid gasoline will enter the evaporative opening 13. Therefore, in the liquid fuel outflow prevention valve of the present embodiment, the support member 3 can move up and down relatively with respect to the housing 10. Therefore, as shown in FIG. 3, when the wavy gasoline liquid level or gasoline splash 200 collides from below with the plate-shaped portion 30 of the support member 3, the kinetic energy of the support member 3 instantaneously rises, and the float valve 2 Rises at an accelerating rate and closes the evaporation opening 13. This prevents gasoline droplets 200 from entering the evaporation opening 13.

Further, even if the float valve 2 does not rise at an accelerated rate, the float valve 2 also rises by the amount that the support member 3 has risen, and the float valve 2 rises at most 2 mm from the position shown in FIG. As a result, the distance between the projection 20 and the evaporation opening 13 is reduced, so that the responsiveness of the float valve 2 is improved, and the projection 20 can easily close the evaporation opening 13.
Therefore, even if the gasoline liquid surface violently undulates, it is possible to prevent liquid gasoline from entering the evaporation opening 13.

In the valley of the wavy gasoline liquid level, the float valve 2 is lowered and the support member 3 is also lowered. Therefore, the evaporator opening 13 is opened, and when the gasoline liquid level and the splash again collide, the support member 3 and the float valve 2 rises and closes the evaporation opening 13. By this repetition, it is possible to prevent liquid gasoline from entering the evaporation opening 13 even if the gasoline level rises.

In the liquid fuel outflow prevention valve of this embodiment, the urging force of the spring 4 is used as an auxiliary means for floating the float valve 2, but such an auxiliary means may be omitted. Other auxiliary means such as magnetic force can also be used. The engagement means between the housing 10 and the support member 3 is not limited to the engagement means of this embodiment as long as the support member 3 can move up and down relatively to the housing 10.

[0028]

That is, according to the liquid fuel outflow prevention valve of the present invention, the open / close performance of the float valve in a normal state is equal to that of the conventional valve, but the response of the float valve when the fuel level is wavy is obtained. Therefore, the entry of the liquid fuel into the evaporation opening can be further suppressed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a liquid fuel outflow prevention valve according to an embodiment of the present invention when a liquid surface is at a low position in a normal state.

FIG. 2 is a cross-sectional view showing the liquid fuel outflow prevention valve of one embodiment of the present invention in a state where the liquid level is at a high position in a normal state.

FIG. 3 is a cross-sectional view showing the liquid fuel outflow prevention valve of one embodiment of the present invention in a state where the liquid surface is wavy.

FIG. 4 is a cross-sectional view showing a conventional liquid fuel outflow prevention valve in a state where the liquid surface is at a low position in a normal state.

FIG. 5 is a cross-sectional view showing a conventional liquid fuel outflow prevention valve in a state where a liquid level is at a high position in a normal state.

FIG. 6 is a cross-sectional view showing a conventional liquid fuel outflow prevention valve in a state where a liquid surface is wavy.

[Explanation of symbols]

1: Gasoline tank 2: Float valve 3: Support member 4: Spring 13: Evaporator opening 14: Slot 15: Gap 200: Splash of gasoline (fuel)

Claims (1)

[Claims] 1. A housing provided at an upper portion of a fuel tank and having an evaporative opening through which vaporized fuel passes, and which is accommodated in the housing, floats on the fuel, and moves up and down by a vertical movement of a liquid level of the fuel. A float valve that opens and closes the evaporator opening; and a support member that is held by the housing and regulates the lowering of the float valve. The support member is held by the housing so as to be at least vertically movable relative to the housing. A liquid fuel outflow prevention valve characterized by being made.