JP2000008981A - Fuel shutoff valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide excellent assembling working property of a fuel tank to a tank upper wall and to reduce the number of part items. SOLUTION: A fuel shutoff valve 20 is equipped with a case body 30 attached to a tank uppers wall FTa, a float 40, a spring 45 and a bottom plate 38, opening or closing a connecting passage 36a by the float 40 according to the fuel level of a fuel tank FT. The case body 30 is welded to the tank upper wall FTa via an annular welded part 35 of a flange part 33. This tank upper wall FTa is made of polyethylene, and the flange part 33 is made of nylon or polyacetal, while the annular welded part 35 is made of an olefinic resin added with a popar functional group so as to have weldability in both of the tank upper wall FTa and the flange part 33.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is directed to a fuel tank for a vehicle, which is disposed above a fuel tank for discharging fuel vapor from the fuel tank at the time of refueling and restricting the fuel flow when the fuel reaches a predetermined liquid level. Fuel shut-off valve.

[0002]

2. Description of the Related Art Conventionally, as this kind of fuel cutoff valve, U.S. Pat. No. 5,404,907 is known, and has a configuration as shown in FIG. In FIG. 5, the fuel cutoff valve 1
Reference numeral 00 denotes a device that is mounted on the tank upper wall FTa of the fuel tank FT, and includes a case main body 102, a lid 110, a float 120, a spring (not shown), and an O-ring 140. The case body 102 includes the upper wall 1
03, a side wall portion 104 integrally formed on the outer peripheral portion of the upper wall portion 103, and a bottom plate 105 attached to a lower end of the side wall portion 104.
02S. A mounting hole 103a is formed in an outer peripheral portion of the upper wall portion 103 of the case main body 102, and an upper projecting portion 103b is formed in a central portion thereof. An annular recess 103c for accommodating the O-ring 140 is formed on the outer peripheral side wall of the upper protruding portion 103b, and a connection passage 103d connected to the float chamber 102S is formed at the axis thereof.

[0003] The float chamber 102S houses a float 120 having a valve portion 120a at an upper portion thereof. The valve portion 120a opens and closes the connection passage 103d. The float 120 is supported by a spring placed on the bottom plate 105.

[0004] On the other hand, the lid 110 is composed of a lid main body 112 assembled to the case main body 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 portion 103 of the case body 102 is fitted into the mounting recess 114a. Further, the flange portion 115 is thermally fused 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 case body 102.
05a, the float chamber 102S, the connection passage 103d, and the outside (canister) through the passage 114a of the lid 110. Then, when the fuel in the fuel tank FT reaches the predetermined liquid level F
When the fuel reaches L1, the fuel flows into the float chamber 102S through the through-hole 105a, and gives buoyancy to float the float 120. The float 12 is raised by the float 120 being raised.
The valve portion 120a formed in the upper portion of the cylinder 0 blocks the connection passage 103d, thereby preventing the fuel from flowing out of the fuel tank FT.

In order to mount the fuel cutoff valve 100 on the tank upper wall FTa of the fuel tank FT, first, a float 120 and a spring are assembled in the case main body 102 and closed by the bottom plate 105. Then, the case body 102 is
Assemble to 10. That is, after attaching the O-ring 140 to the annular recess 103c of the upper protruding portion 103b of the case main body 102, the upper protruding portion 103b is fitted into the mounting recess 114a of the lid 110. Further, the joining end face 115a of the flange portion 115 is heated by a heat sealing plate (not shown), and the peripheral edge of the tank mounting hole FTc of the fuel tank FT is also heated by the heat welding plate (not shown). Then, the two parts are heat-welded by combining the melted parts.

[0007]

However, the case body 1
02, the lid 110 and the O-ring 140, the fuel cutoff valve 100 has been required to further reduce the number of parts. That is, the use of the O-ring 140 not only makes the mounting workability not good, but also
The number of parts has increased, which has been a factor of cost increase. Moreover, the case body 1 made of nylon
02 is a tank upper wall F made of polyethylene.
Since it cannot be welded to Ta, the tank upper wall FTa
Is attached via a lid 110 that can be thermally welded.

An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a fuel shut-off valve which is excellent in workability of assembling a fuel tank to a tank upper wall and has a reduced number of parts. I do.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is provided in a mounting hole formed in a tank upper wall of a fuel tank, so that the inside and outside of the fuel tank can be connected to each other. In a fuel cutoff valve that opens and closes a connection passage to connect and shut off communication between the fuel tank and the outside, a cylindrical side wall inserted into the mounting hole, a ceiling wall integrally formed with the side wall, A case formed with an outer peripheral portion of the ceiling wall portion and a flange portion formed so as to cover an outer peripheral side of the mounting hole, and forming a float chamber surrounded by the side wall portion and the upper wall portion in a cup shape; A main body, a float housed in the float chamber, and rising and lowering by increasing or decreasing the buoyancy according to the fuel level of the fuel tank to open and close the connection passage; and a float interposed between the flange portion and the tank upper wall. With the annular weld The surface portion of the tank upper wall is formed of polyethylene, the flange portion is formed of nylon or polyacetal, and the annular welded portion is formed on both the surface layer portion of the tank upper wall and the flange portion. It is characterized by being formed from a modified olefin resin to which a polar functional group is added so as to have a welding property.

[0010] The fuel cutoff valve according to the present invention is mounted on the upper wall of the tank of the fuel tank, and when the fuel level rises by refueling the fuel tank, the fuel vapor in the fuel tank flows from the float chamber through the connection passage. Outflow to the outside. When the fuel reaches a predetermined liquid level in the fuel tank, the float rises by increasing buoyancy to close the connection passage, thereby preventing the fuel from flowing out of the fuel tank.

[0011] The case main body constituting the fuel cutoff valve includes:
It is formed in a cup shape by the side wall part and the ceiling wall part,
With the side wall portion inserted into the mounting hole, a flange portion provided on the outer peripheral side of the ceiling wall portion is welded to the surface layer portion of the tank upper wall via an annular welding portion. The annular welded portion is formed of a modified olefin resin to which a polar functional group has been added, and is thermally welded to both the tank upper wall formed of polyethylene and the flange portion formed of nylon. That is, although polyethylene and nylon are not compatible with each other, both can be welded by interposing a modified olefin resin to which a polar functional group is added.

As described above, when the case body is assembled to the upper wall of the tank, if the flange portion is welded to the upper wall of the tank via the annular welding portion, the mounting hole is closed, and the inside of the fuel tank and the outside of the fuel tank are closed. , Which eliminates the need for a separate sealing member such as an O-ring and reduces the number of parts. In addition, for the case body and the tank upper wall, a resin material most suitable for each use can be selected without considering the heat welding property.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to further clarify the configuration and operation of the present invention described above, preferred embodiments of the present invention will be described below.

FIG. 1 is a sectional view showing a fuel cutoff valve 20 mounted on an upper portion of a fuel tank FT of an automobile according to an embodiment of the present invention. In FIG. 1, the fuel tank F
T has a multilayer structure in which polyethylene, nylon resin and the like are laminated, and the surface layer portion is formed of polyethylene resin. A mounting hole FTb is formed in a tank upper wall FTa of the fuel tank FT, and the fuel tank FT is mounted with a part of the fuel cutoff valve 20 inserted. Fuel cutoff valve 20
Indicates that the fuel in the fuel tank FT has a predetermined liquid level FL at the time of refueling.
When it rises to 1, it regulates outflow to the outside (canister).

FIG. 2 is an exploded sectional view of the fuel cutoff valve 20. The fuel cutoff valve 20 includes a case body 30 and a bottom plate 38.
, A float 40 and a spring 45 as main components. The case main body 30, the bottom plate 38, and the float 40 are formed of polyacetal or nylon having fuel oil resistance.

The case body 30 includes a ceiling wall 32,
A cup-shaped float chamber 30S is formed, which is provided with a side wall portion 37 extending cylindrically downward from the ceiling wall portion 32 and surrounded by the ceiling wall portion 32 and the side wall portion 37. 30a.

The outer peripheral portion of the ceiling wall portion 32 has a side wall portion 37.
Is a disk-shaped flange portion 33 larger than the outer diameter of. As shown in FIG. 3, an annular welding portion 35 is welded to a lower portion of the outer periphery of the flange portion 33. Annular weld 3
Reference numeral 5 denotes an annular mounting base 35a and a projecting welded portion 35b projecting from the lower end of the mounting base 35a and projecting from the lower surface of the flange 33. Mounting base 35
“a” is formed wider than the protruding welded portion 35 b, and is buried in the end of the flange 33 so as to be prevented from being removed from the flange 33. The annular welded portion 35 can be formed by an injection molding method using insert molding or two-color molding.

Here, the material of the annular welded portion 35 is a resin obtained by introducing a polar functional group into a nonpolar olefin resin. In other words, the annular welded portion 35 has adhesiveness to polyethylene or the like as an intrinsic property of the olefin resin, and also has adhesiveness to nylon or polyacetal resin by introducing a polar functional group. Things. Examples of polar functional groups that add such properties include a carboxyl group, a hydroxyl group, an amino group, a halogen group, and an acryl group. For example, Admer (manufactured by Mitsui Petrochemical Industries, Ltd .: trade name), Bond First (Sumitomo Chemical Co., Ltd .: trade name), and Modic (Mitsubishi Yuka Corporation: trade name) can be used.

Therefore, the annular welded portion 35 is made of an olefin resin having a polar functional group and is embedded in the flange portion 33 by insert molding or the like, so that the annular welded portion 35 is integrally welded to the flange portion 33.

The annular welding portion 35 is provided in the fuel tank FT.
Is also welded to the annular groove FTc of the mounting hole FTb. That is, since the annular welded portion 35 is formed of a nonpolar olefin-based resin, it is welded to the polyethylene tank upper wall FTa from its original property.

Returning to FIG. 2, at the center of the ceiling wall 32,
A communication pipe portion 36 having a connection passage 36a is formed. The connection passage 36a is an L-shaped passage, and communicates with the float chamber 30S and the external canister. The side of the communication chamber 36 on the float chamber 30S side is a conical seat 36b.

An engagement hole 37a is formed in a lower portion of the side wall portion 37 of the case body 30. This engagement hole 37
a is for attaching the bottom plate 38 as described later. Further, guide protrusions 37 for guiding the float 40 extending in the vertical direction are provided on the inner peripheral portion of the side wall portion 37.
b is formed.

The bottom plate 38 is a member that closes the lower opening 30a of the case main body 30, and the engagement portion 38a formed on the outer periphery thereof engages with the engagement hole 37a.
The case body 30 is mounted so as to close the lower opening 30a. The bottom plate 38 is formed with a communication hole 38b for communicating the float chamber 30S with the inside of the fuel tank FT. Therefore, the inside of the fuel tank FT communicates with the float chamber 30S through the communication hole 38b. A spring support 38c is formed at the upper center of the bottom plate 38. The spring support portion 38c supports the spring 45 between the spring 45 and the inner lower surface of the float 40.

The float 40 housed in the float chamber 30S is formed in a container shape having an upper wall portion 41 and a cylindrical side wall portion 42 formed below the outer periphery of the upper wall portion 41. The inside space is a buoyancy chamber 40S for generating buoyancy.

Next, the operation of the fuel cutoff valve 20 will be described. 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 is increased toward the canister through the float chamber 30S and the connection passage 36a. Escaped.

When the fuel level in the fuel tank FT reaches a predetermined level FL1, the fuel flows into the float chamber 30S through the communication hole 38b of the bottom plate 38. As a result, the float 40 rises due to buoyancy, and closes the connection passage 36a with the valve portion 41a to prevent fuel from flowing 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.

Next, the operation of attaching the fuel cutoff valve 20 to the tank upper wall FTa of the fuel tank FT will be described.
2, the float 40 and the spring 45 are housed in the float chamber 30S of the case body 30, and the lower end of the spring 45 is aligned with the spring supporting portion 38c of the bottom plate 38, and the engaging portion 38a of the bottom plate 38 Is engaged with the engagement hole 37 a of the side wall portion 37, and the bottom plate 38 is attached to the case main body 30.

Subsequently, as shown in FIG.
5 is melted by the hot plate Hp1 while the annular groove FTc along the periphery of the mounting hole FTb of the fuel tank FT is melted by the hot plate Hp2 to melt the welded portion Fb.
Let it be Td. Then, the side wall portion 37 of the case body 30 is inserted into the mounting hole FTb of the tank upper wall FTa, and the annular welded portion 35 is pressed against the welded portion FTd. At this time, since the annular welded portion 35 is formed from an olefin-based resin,
When cooled and solidified with respect to the tank upper wall FTa made of polyethylene, they fuse with each other.

Therefore, if the annular welding portion 35 is welded to the tank upper wall FTa of the fuel tank FT, the fuel tank FT
Inner and outer seals can be made simultaneously. As described above, the polyethylene of the tank upper wall FTa and the nylon of the case main body 30 are not originally compatible with each other, but they can be hermetically sealed by interposing the annular welded portion 35. By using the annular welded portion 35 according to the present embodiment, the number of parts can be reduced because the O-ring as described in the related art is not required.

Moreover, the annular welded portion 35 is welded to the flange portion 33 and is insert-molded, so that the mounting base 3 wider than the projecting welded portion 35b.
5a also prevents removal from the flange portion 33, so that the mechanical joining strength is high.

The case body 30 includes a fuel tank FT.
Since it is formed of a resin material different from that of the tank upper wall FTa, it is possible to select a material most suitable for each application while ensuring high sealing performance.

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

(1) In the above embodiment, before welding the case body 30 to the tank upper wall FTa, the flange 3
3, the annular welded portion 35 is previously welded by insert molding or the like. However, the present invention is not limited thereto. A welding step may be employed.

[Brief description of the drawings]

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

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

FIG. 3 is an enlarged sectional view of the vicinity of an annular welded portion 35;

FIG. 4 is an explanatory view illustrating a step of welding the case body 30 to the tank upper wall FTa via the annular welding portion 35.

FIG. 5 is a sectional view showing a conventional fuel cutoff valve 100.

[Explanation of symbols]

 Reference Signs List 20: fuel cutoff valve 30: case body 30S: float chamber 30a: lower opening 32: ceiling wall 33: flange portion 35: annular welded portion 35a: mounting base 35b ... projecting welded portion 36: communicating pipe portion 36a: connecting passage 36b ... Seat part 37 ... Side wall part 37a ... Engaging hole 37b ... Guide ridge 38 ... Bottom plate 38a ... Engaging part 38b ... Communication hole 38c ... Spring support part 40 ... Float 40S ... Buoyancy chamber 41 ... Upper wall part 41a ... Valve part 42 ... side wall part 45 ... spring FT ... fuel tank FTa ... tank upper wall FTb ... mounting hole FTc ... annular groove Hp1 ... hot plate Hp2 ... hot plate FTd ... welding portion

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tomohide Aoki 1 Ochiai Nagahata, Kasuga-machi, Nishikasugai-gun, Aichi Prefecture Inside Toyoda Gosei Co., Ltd. F-term (reference) in Toyoda Gosei Co., Ltd. 3D038 CA04 CA15 CA22 CA25 CA26 CA27 CB01 CC05 CC17 CC19 3H055 AA03 AA22 BA17 BB18 BC06 BC07 BC09 CC04 CC08 CC20 CC21 GG22 GG26 JJ03

Claims (1)

[Claims] 1. A fuel cutoff valve which is mounted in a mounting hole formed in a tank upper wall of a fuel tank and opens and closes a connection passage for connecting the inside of the fuel tank and the outside, thereby shutting off the communication between the fuel tank and the outside. A cylindrical side wall portion to be inserted into the mounting hole, a ceiling wall portion integrally formed with the side wall portion, and an outer peripheral portion of the ceiling wall portion formed to cover an outer peripheral side of the mounting hole. And a case body forming a float chamber surrounded by the side wall and the upper wall in a cup shape, and a buoyancy that is housed in the float chamber and increases / decreases buoyancy according to the fuel level of the fuel tank. A float that moves up and down to open and close the connection passage, and an annular welded portion interposed between the flange portion and the tank upper wall.The surface layer portion of the tank upper wall is formed of polyethylene, The above flange is Along with being formed from nylon or polyacetal, the annular welded portion is formed from a modified olefin resin to which a polar functional group is added so as to have weldability to both the surface layer portion and the flange portion of the tank upper wall. A fuel cutoff valve.