JP2001271953A - Fuel cutoff valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cutoff valve 20 to ensure high sealing ability even when vertical oscillation of a vehicle is applied when a float 40 is submerged in liquid. SOLUTION: A fuel cutoff valve 20 is attached to an upper part 41 of a fuel tank FT and a connection passage 32b to interconnect the fuel tank FT and an external part (a canister) is cut off according to a fuel level in the fuel tank FT. The fuel cutoff valve 20 is provided with a casing 30 to form a valve chamber 30S and a float 40 contained in a valve chamber 30S and opening and closing the connection passage 32b according to a fuel level in the fuel tank FT. The float 40 is formed such that the drainage volume of an upper part 41 of the float is increased to a value higher than that of a lower part 42 thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cutoff valve mounted on an upper portion of a fuel tank for opening and closing a connection passage connecting the inside and the outside of the fuel tank so as to cut off communication between the fuel tank and the outside.

[0002]

2. Description of the Related Art Conventionally, as a fuel cutoff valve of this type, FIG.
The configuration shown in FIG. In FIG. 12, a fuel cutoff valve 100 is mounted on a tank upper wall FTa of a fuel tank FT, and includes a casing 102 and a lid 110.
, A float 120 and a spring 130. The casing 102 includes an upper wall 103 and the upper wall 10.
3 and a side wall 104 formed integrally with the outer periphery of the side wall 10.
And a bottom plate 105 attached to a lower end of the valve chamber 4, and an inner space thereof is defined as a valve chamber 102S.

[0003] The valve chamber 102S has a valve section 1 above it.
A float 120 having 20a is stored. The valve portion 120a opens and closes a connection passage 103d connected to the outside of the fuel tank FT. Float 120
Is supported by a spring 130 mounted on the bottom plate 105.

On the other hand, a lid body 110 includes a lid main body 112 assembled to the casing 102, and a lid passage forming portion 114.
And a flange portion 115, which are integrally formed. A mounting recess 114a is formed in the lid body 112, and the upper protruding portion 103b of the upper wall 103 of the casing 102 is fitted into the mounting recess 114a. Also,
An engaging projection 103a is formed on an upper portion of the casing 102, and is engaged with the engaging hole 112a of the support member on the lid 110 side, whereby the casing 102 and the lid 110 are assembled. Further, the flange portion 115 is heat-welded to the tank upper wall FTa of the fuel tank FT at the joint end surface 115a.

[0005] In the fuel cutoff valve 100 having the above structure, when fuel is supplied to the fuel tank FT, the fuel vapor in the fuel tank FT passes through the through hole 1 formed in the bottom plate 105 of the casing 102.
05a, valve chamber 102S, connection passage 103d, lid 110
Flows out to the outside (canister) through the passage 114b. Then, when the fuel to the fuel tank FT is at the predetermined liquid level FL1
When the fuel reaches the valve chamber 102 through the through hole 105a.
It flows into S and gives buoyancy to float the float 120. When the float 120 rises, the valve portion 120a formed above the float 120 closes the connection passage 103d, thereby preventing the fuel from flowing out of the fuel tank FT.

[0006]

However, in the conventional fuel cutoff valve 100, when the fuel in the fuel tank FT is full, or when the float 120 becomes submerged due to the inclination of the vehicle, When a large vertical vibration is applied to the casing 102 due to the shaking of the vehicle, the float 120 attempts to maintain its position by inertial force.
There has been a problem that the sealing force of the 20 valve portions 120a with respect to the seat portion is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art. When the float is submerged, high sealing performance can be obtained even when the vehicle is shaken in the vertical direction. It is an object of the present invention to provide a fuel cutoff valve which can be secured.

[0008]

Means for Solving the Problems and Action / Effect The first aspect of the present invention for solving the above-mentioned problems is that a connecting passage for connecting the fuel tank and the outside is mounted on the upper portion of the fuel tank. A fuel cutoff valve that shuts off according to the fuel level in a tank, a casing that forms a valve chamber connected to the connection passage, and the connection that is housed in the valve chamber and that connects according to the fuel level in the fuel tank. A float for opening and closing the passage, wherein the float has a larger drainage volume in an upper part than in a lower part of the float.

In the fuel cutoff valve according to the present invention, when the fuel tank is low in fuel level, the fuel vapor in the fuel tank is released to the outside (canister) by communicating with the canister. On the other hand, when the liquid level of the fuel in the fuel tank rises, the float floats, and the valve portion of the float closes the connection passage, thereby preventing the fuel in the fuel tank from flowing out.

In such a fuel cutoff valve, when the float is submerged when the fuel tank is refueled or the vehicle is tilted, the float increases the buoyancy. At this time, the drainage volume is larger at the upper part of the float than at the lower part of the float, and the rate of increase in the buoyancy of the float increases as it floats to the upper part. Therefore, with the float submerged,
Even if a vertical vibration is applied to the fuel cutoff valve, the valve portion of the float is seated on the seat surface with a large force to close the connection passage, so that high sealing performance can be obtained.

As a preferred embodiment of the above-mentioned float, a configuration in which a hollow chamber is formed above the float can be adopted. With such a hollow chamber, even if the upper part of the float is enlarged, its weight can be reduced, so that a high sealing force by the float can be secured.

[0012]

FIG. 1 is a sectional view showing a fuel cutoff valve 20 mounted on an upper part of a fuel tank FT of an automobile according to an embodiment of the present invention. In FIG. 1, the surface of a fuel tank FT is formed of a composite resin material containing polyethylene, and a mounting hole FTc is formed in the tank upper wall FTa. The fuel cutoff valve 20 is attached to the tank upper wall FTa with its lower part protruding into the attachment hole FTc. The fuel cutoff valve 20 regulates the outflow to the outside (canister) when the fuel in the fuel tank FT rises to a predetermined liquid level FL1 during refueling.

FIG. 2 is an exploded sectional view of the fuel cutoff valve 20. The fuel cutoff valve 20 includes a casing 30 and a bottom plate 35.
, A float 40, a spring 46, and a lid 50 as main components. Casing 30, bottom plate 3
5 and the float 40 are formed from a synthetic resin polyacetal having excellent fuel oil resistance. The lid body 50 is formed of polyethylene which has excellent fuel oil resistance and can be thermally welded to the fuel tank FT. Although these resin materials have both fuel swelling resistance, the casing 3
0 and the polyacetal constituting the float 40 are more suitable for improving the sealing characteristics of the valve.
Has better fuel swellability than polyethylene.

The casing 30 has a ceiling wall 32 and a side wall 33 extending downwardly from the ceiling wall 32 in a cylindrical shape, and a cup-shaped valve chamber 30S surrounded by the ceiling wall 32 and the side wall 33. Is formed, and the lower part thereof is a lower opening 30a. An upper protruding portion 32a is formed at the center of the ceiling wall 32 of the casing 30. A connection passage 32b penetrates through the upper protruding portion 32a, and the connection passage 3b
The valve chamber 2S side of 2b is a conical seat portion 32d. An annular step portion 32f for supporting the O-ring 36 is formed on the outer peripheral side wall of the upper protruding portion 32a.

The lower portion of the side wall 33 has an engagement hole 33a.
Are formed. The engagement hole 33a is for attaching the bottom plate 35 as described later. Further, a ventilation hole 33c communicating with the valve chamber 30S is provided in an upper portion of the side wall 33.
Are formed at equal intervals in the circumferential direction.

The bottom plate 35 is a member that closes the lower opening 30a of the casing 30, and an engagement portion 35a formed on the outer periphery of the bottom plate 35 engages with the engagement hole 33a.
The casing 30 is mounted so as to close the lower opening 30a. A communication hole 35b for communicating the valve chamber 30S with the inside of the fuel tank FT is formed in the center of the bottom plate 35.
Therefore, the inside of the fuel tank FT communicates with the valve chamber 30S through the communication hole 35b. Further, an annular spring support portion 35c is formed at the upper center of the bottom plate 35. The spring support portion 35c supports the spring 46 between itself and the lower surface of the float 40.

The float 40 housed in the valve chamber 30S has an upper portion 41 and a lower portion 42 formed integrally with the upper portion 41. The upper part 41 has a larger diameter than the lower part 42. Guide protrusions 40 a are formed at predetermined intervals in the vertical direction on the outer peripheral portion of the upper portion 41. The lower portion 42 has a cylindrical shape projecting from the lower end of the upper portion, and the inner space thereof is a buoyancy chamber 40S for generating buoyancy. Therefore, since the upper part 41 has a larger outer diameter than the lower part 42, the drainage volume when submerged is large.

On the other hand, the lid 50 includes a lid main body 51, a tubular body 52 projecting from the center of the lid main body 51 to an upper part in an L-shape,
It has a flange 53 formed on the outer periphery of the lid main body 51 and a support 54 projecting from the lower part of the lid main body 51, and these are integrally formed. A lid fitting portion 51a for fitting the upper protruding portion 32a of the casing 30 is formed at the lower center of the lid main body 51. In addition, the tubular body 52
Is formed with a lid-side passage 52a. One end of the lid-side passage 52a is connected to the connection passage 32b of the casing 30, and the other end is connected to the canister side. Further, at the lower end of the flange portion 53, an annular welded end 53a welded to the tank upper wall FTa of the fuel tank FT is formed. The support member 54 is formed in a tubular shape so as to fit the upper portion of the casing 30 and has a slit 54a and an engagement hole 54b having a lower end partly opened.
Are formed.

Next, the operation of mounting the fuel cutoff valve 20 on the tank upper wall FTa of the fuel tank FT will be described. 2, the float 40 and the spring 46 are housed in the valve chamber 30S of the casing 30, and the lower end of the spring 46 is aligned with the spring supporting portion 35c of the bottom plate 35, and the engaging portion 35a of the bottom plate 35 is The bottom plate 35 is attached to the casing 30 by engaging with the engagement holes 33 a of the side wall 33. Further, the O-ring 36 is mounted on the upper protruding portion 32a and held on the annular step portion 32f. In this state, the support body 54 is fitted on the upper portion of the casing 30, and the upper protruding portion is protruded from the lid fitting portion 51a. The part 32a is fitted. At this time, the engagement protrusion 39 is engaged with the engagement hole 54b. Thereby, the lid 50 and the casing 30 are integrated.

Subsequently, the lower end of the annular welding end 53a of the lid 50 is melted by a hot plate (not shown), and is melted by a hot plate (not shown) along the periphery of the mounting hole FTc of the fuel tank FT. The welded portion FTd (FIG. 1). The casing 30 is inserted from below into the mounting hole FTc, and the annular welded end 53a is pressed against the welded portion FTd. Thus, since the annular welded end 53a and the welded portion FTd are formed of the same resin material, they are welded to each other when cooled and solidified. As described above, when the lid 50 is welded to the tank upper wall FTa, the inside of the fuel tank FT is ensured to have a high sealing property to the outside.

Next, the operation of the fuel cutoff valve 20 will be described. In FIG. 1, when fuel is supplied into the fuel tank FT by refueling, the fuel vapor accumulated in the upper portion of the fuel tank FT as the fuel level in the fuel tank FT rises increases, and the fuel vapor in the upper part of the fuel tank FT is changed to the ventilation hole 33 c of the casing 30. The gas is released to the canister side through the valve chamber 30S, the connection passage 32b, and the lid-side passage 52a. Then, when the fuel level in the fuel tank FT reaches a predetermined level FL1, the fuel flows into the valve chamber 30S through the communication hole 35b of the bottom plate 35. As a result, buoyancy is generated in the float 40 and the float 40 rises to close the connection passage 32b with the valve portion 41a, so that fuel does not flow out to the canister side.
Therefore, when fuel is supplied to the fuel tank FT, the fuel vapor can be released from the fuel tank FT and the fuel can be prevented from flowing out of the fuel tank FT.

FIG. 3 is an explanatory view showing a state where the float 40 of the fuel cutoff valve 20 is floating and seated, and FIG. 4 is an explanatory view showing a state where the fuel cutoff valve 20 is inclined. here,
The force F when the float 40 is seated on the seat portion 32d is expressed by the following equation (1), as can be seen from the balance of the force F in FIG. F = ρV + w−W (1) ρ: Fuel density V: Drainage volume V w: Spring load W: Weight of float 40 In equation (1), spring load w is float 40
Is not so large, and therefore the amount of deformation of the spring 46 does not change so much, it can be considered almost constant, and since the weight W of the float 40 is also constant, F is the drainage volume. It can be considered that it is almost proportional to V. This relationship is shown in FIG. Figure 5 shows the liquid level FL
Is a graph showing a relationship between the buoyancy f (ρV) of the float 40 and a force F when the float 40 is seated, wherein a solid line indicates the present embodiment and a broken line indicates a conventional example.

In FIG. 5A, the buoyancy f increases at the rate of the straight line k1 at the fuel level FLa from the lower end of the float 40 to the upper end of the lower part 42, and at the rate of the straight line k2 at a higher level. Increase, that is, the top 4 of the float 40
1 increases buoyancy at a greater rate. Therefore, the float 40 has a large buoyancy f at the upper portion 41, and therefore, the float 40 has a structure shown in FIG.
As shown in (B), the seating force F is larger than that of the float having the same outer diameter in the conventional example.

Further, in the float 40 of the present embodiment,
Since only the upper portion 41 is formed to have a large diameter, the force F is not large when only the lower portion 42 is immersed in the fuel. Therefore, the state where the connection passage 32b is reliably opened is maintained, and the fuel vapor is transferred to the canister side. You can escape to. On the other hand, when the fuel level reaches the upper part 41 of the float 40, the force F is increased, so that the float 40 becomes submerged and the float Valve portion 41a exerts a large force F on seat portion 32d.
To close the connection passage 32b. Therefore, even in the state where the float 40 is submerged, high sealing performance can be obtained.

Furthermore, the float 40 has the following effects as compared with a shape in which the whole has a large diameter and buoyancy is increased. If the float 40 has a large diameter over the entire length in the height direction, the float 40 closes due to increased buoyancy before reaching the full tank position. If such a state is to be avoided by means for reducing the spring load, the allowable range of the spring load is narrowed, and the manufacture of the spring 46 becomes difficult. On the other hand, the float 40 of the present embodiment is easy to manufacture because only the outer shape is changed.

FIG. 6 is a sectional view showing a fuel cutoff valve 20B according to the second embodiment. In FIG. 6, the fuel cutoff valve 20B is characterized in that a guide fin 42Ba is provided on a lower portion 42B of a float 40B. That is, guide fins 42Ba protrude from the outer periphery of the lower portion 42B of the float 40B at predetermined intervals in the circumferential direction.
The outer diameter of the guide fin 42Ba is the float 40B.
Is substantially the same as the outer diameter of the upper portion 41B of the upper portion. Therefore, the outer end of the guide fin 42Ba is disposed so as to be slidably supported on the inner wall surface of the casing 30. Since such guide fins 42Ba guide the float 40B to the inner wall surface of the casing 30, the float 40B
B can perform the elevating operation in a stable posture.

FIG. 7 is a sectional view showing a fuel cutoff valve 20C according to the third embodiment. The fuel cutoff valve 20C is characterized in that the shape of the bottom body 35C matches the shape of the lower part 42C of the float 40C. That is, the bottom body 35C
Is a cup-shaped cup portion 35Ca having an inner diameter slightly larger than the lower portion 42C of the float 40C, and a cup portion 3
It is integrally formed with the flange portion 35Cb of the upper portion 41C of 5Ca. Casing 30C with flange 35Cb
And a bottom body 35C is mounted on the casing 30C. Further, a ventilation hole 33c is formed in a side wall 33C of the cup portion 35Ca. When refueling, vent holes 33c
When the fuel vapor flows from the valve chamber 30S into the valve chamber 30S, the flow of the fuel vapor hits the side wall of the float 40C and
It does not serve as a force to raise OC directly upward. Therefore, the float 40C is not blown up by the fuel vapor and closed at a position lower than the predetermined valve closing position. In addition,
A small hole 35Cc is formed at the bottom of the bottom body 35C to prevent fuel from being accumulated in the cup portion 35Ca.

FIGS. 8 to 11 are sectional views showing a float according to another embodiment. In these embodiments, the drainage volume is increased without increasing the weight of the float. That is, a decrease in sealing force caused by increasing the weight of the float is avoided.

(1) The float 40D shown in FIG. 8 is characterized in that it is divided into two to form a hollow chamber 40Da. That is, the float 40D is
And a float lower body 42D. A hollow recess 41Da is formed in the float upper body 41D, while a hollow recess 4D of the float upper body 41D is formed in the float lower body 42D.
A flange 42Da for closing 1Da is formed. At the outer peripheral end of the flange 42Da, the float body 4
The hollow chamber 40Da is thermally welded to the outer peripheral end of the 1D.
Are formed. The weight of the float 40D can be reduced by the capacity of the hollow chamber 40Da.

(2) The float 40E of FIG. 9 is characterized in that the hollow chamber 40Ea is formed by gas injection. That is, when injection molding the float 40E, the hollow chamber 40Ea is formed by injecting gas from the injection hole 40Eb.

(3) The float 40F shown in FIG. 10 is characterized in that a downward recess is formed to form an air pocket. That is, a recess 40Fa that opens downward is formed in the upper part of the float 40F. The recess 40Fa increases buoyancy by forming an air pocket when the liquid level reaches the lower end of the upper portion of the float 40F.

(4) The float 40G shown in FIG. 11 is characterized in that a lightweight foam floating body 43G is mounted on the upper part thereof. That is, the float 40G is composed of a float body 41G and a foamed floating body 43G made of a doughnut-shaped foam material.
And an annular recess 41G on the upper part of the float main body 41G.
The fitting hole 43Ga of the foam floating body 43G is fitted and positioned at a. Such a foamed floating body 43G has a smaller gravitational force than polyacetal, so that a large buoyancy is generated as compared to the volume.

The present invention is not limited to the above-described embodiment, but can be embodied in various modes without departing from the gist thereof. For example, the following modifications are possible.

(1) In the above embodiment, the fuel cutoff valve 20 is mounted on the resin fuel tank FT by heat welding. However, the fuel cutoff valve 20 can be applied to various fuel tanks to which a float valve can be mounted. For example, a configuration in which a gasket is interposed in an iron fuel tank with bolts and nuts may be used.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a fuel cutoff valve 20 mounted on an upper part of a fuel tank FT of an automobile according to a first embodiment of the present invention.

FIG. 2 is an exploded sectional view of the fuel cutoff valve 20.

FIG. 3 is an explanatory diagram illustrating an operation of a float 40.

FIG. 4 is an explanatory view showing a state in which a fuel cutoff valve is inclined and a float 40 is floating.

FIG. 5 is a graph showing a relationship between a liquid level FL of the fuel, a buoyancy f of the float 40, and a force F when the float 40 is seated.

FIG. 6 is a sectional view showing a fuel cutoff valve 20B according to a second embodiment.

FIG. 7 is a sectional view showing a fuel cutoff valve 20C according to a third embodiment.

FIG. 8 is a sectional view showing a float 40D according to the fourth embodiment.

FIG. 9 is a sectional view showing a float 40E according to a fifth embodiment.

FIG. 10 is a sectional view showing a float 40F according to a sixth embodiment.

FIG. 11 is a sectional view showing a float 40G according to a seventh embodiment.

FIG. 12 is a sectional view showing a conventional fuel cutoff valve 100.

[Explanation of symbols]

 Reference Signs List 20: fuel cutoff valve 20B: fuel cutoff valve 20C: fuel cutoff valve 30S: valve chamber 30: casing 30C: casing 30a: lower opening 32a: upper protruding portion 32b: connection passage 32d: seat portion 32f: annular step portion 32: ceiling Wall 33 ... Side wall 33a ... Engagement hole 33c ... Vent hole 33C ... Side wall 35a ... Engagement part 35b ... Communication hole 35c ... Spring support part 35 ... Bottom plate 35C ... Bottom body 35Ca ... Cup part 35Cb ... Flange part 35Cc ... Pores 39 ... engaging projection 40 ... float 40S ... buoyancy chamber 40a ... guide ridge 40B ... float 40C ... float 40D ... float 40Da ... hollow chamber 40E ... float 40Ea ... hollow chamber 40Eb ... injection hole 40F ... float 40Fa ... recess 40G ... float 41 ... upper part 41B ... upper part 41C ... upper part 41D ... float upper body 1Da ... hollow recess 41a ... valve part 41G ... float main body 41Ga ... annular recess 42D ... float lower body 42C ... lower part 42Da ... flange 42B ... lower part 42Ba ... guide fin 42 ... lower part 43G ... foam floating body 43Ga ... fitting hole 46 ... Spring 50 ... Lid 51 ... Lid body 51a ... Lid fitting part 52 ... Tube part 52a ... Lid side passage 53 ... Flange part 53a ... Circular welded end 54 ... Support body 54a ... Slit 54b ... Engagement hole FT ... Fuel tank FTa: tank upper wall FTc: mounting hole FTd: welded part

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02M 37/00 311 B60K 15/02 E (72) Inventor Nishi Hiroshi Ochiai Ogatai Kasuga-cho, Nishikasugai-gun, Aichi Prefecture 1 No. 1 Toyoda Gosei Co., Ltd. (72) Inventor Eimori Mori 1 Ochiai Ogata, Kasuga-cho, Nishi-Kasugai-gun, Aichi Prefecture F-term (reference) 3D038 CA15 CA22 CC04 CC20 3H055 AA02 AA22 BA17 BC09 CC04 CC07 CC20 CC21 GG08 JJ03 JJ20

Claims (2)

[Claims] 1. A fuel cutoff valve mounted on an upper part of a fuel tank and for shutting off a connection passage connecting the fuel tank and the outside according to a fuel level in the fuel tank, wherein the valve is connected to the connection passage. A casing that forms a chamber, and a float that is housed in the valve chamber and opens and closes the connection passage according to the fuel level in the fuel tank. A fuel cutoff valve having a large drainage volume. 2. The fuel cutoff valve according to claim 1, wherein a hollow chamber is formed above the float.