JPH05149468A - Fuel cut-off device for fuel tank - Google Patents

Abstract

PURPOSE:To enhance joint strength as well as to properly secure a passage from a valve seat to an evaporation passage by processing a case-upper and a case-lower with both the evaporation passage and the valve seat arranged coaxially by means of insert molding. CONSTITUTION:A fuel cut-off device 1 is fitted onto the upper section wall of a tank main body 2, and evaporated fuel gas within the tank main body 2 is thereby set free toward an evaporation passage 5 so as to be led to a canister. And the casing of the fuel cut-off device 1 is made up of a case-upper 7 furnished with the evaporation passage 5, and of a case-lower 10 furnished with a valve housing wall 8 and a valve seat 9, and the like. In this case, when the case lower 10 is formed, the case-upper 7 formed in advance is set in the inside of a molding form in a state that an insert pin is inserted in the vertical passage 16 of the case upper 7. Insert molding is so processed that resin material is made to pass through a gap between a large diameter section 17 and the insert pin so as to be filled in a hollow section 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cutoff device for preventing the outflow of fuel in a fuel tank mounted on a vehicle such as an automobile.

[0002]

2. Description of the Related Art Some fuel tanks for automobiles are provided with a fuel shut-off device so that fuel does not flow out of the evaporative tube portion due to fluctuations in the fuel level in the tank body. As the fuel cutoff device, a device using a float is generally adopted. This is because a resin casing provided in the upper part of the tank body is provided with an evaporation passage and has a float that floats due to the inflow of fuel. When the fuel is accommodated and the fuel level in the tank body changes due to turning and tilting of the vehicle and the fuel flows into the casing, the float in the casing rises due to buoyancy and closes the evaporation passage. ..

By the way, in recent years, the tank main body of the fuel tank tends to be formed of a resin material. In such a fuel tank, a fuel cutoff device is provided by welding which has good workability in mounting and requires a small number of parts. It is desired to be attached to the tank body.

When the fuel cutoff device is attached to the tank body by welding, if the fuel cutoff device is made of resin of the same material as that of the tank body, no particular problem will occur. It may not be possible to form it with the resin of the material. Conventionally, in such a case, only the case upper with the evaporation passage is made of the same resin as the tank body, and the case lower with the valve housing wall and the valve seat is made of a different material. It is considered that the case lower is clipped and the case upper is welded to the tank body.

This related technique is disclosed in, for example, Japanese Utility Model Laid-Open No. 62-91.
No. 721, etc.

[0006]

However, in the case of this conventional fuel cutoff device, since the case upper and the case lower are clipped, the case upper and the case lower are coupled by aging due to the difference in the swelling amount of the two resin materials. There is a problem that the strength decreases, and it is difficult to accurately align the center of the evaporation passage integrally formed on the case upper side with the center of the valve seat integrally formed on the case lower side. Another problem is that the passage is easily narrowed.

Therefore, the present invention is to provide a fuel cutoff device for a fuel tank which has a high coupling strength between the case upper and the case lower and which can surely secure a passage from the valve seat to the evaporation passage. ..

[0008]

According to the present invention, as means for solving the above-mentioned problems, a case upper having an evaporation passage and a case lower having a valve housing wall and a valve seat are made of different resin materials. In the fuel cutoff device for the fuel tank, the case upper and the case lower are insert-molded with the evaporation passage and the valve seat being coaxial.

[0009]

[Function] The case upper and the case lower are integrated by insert molding at the molding stage, and the evaporative passage and the valve seat are centered at the insert molding stage of the case upper and case lower. It fits.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to FIGS.

1 to 3, reference numeral 1 denotes a fuel cutoff device according to the present invention. The fuel cutoff device 1 is attached to an upper wall of a tank body 2 made of resin, and a fuel a in the tank body 2 is In the normal state where there is no large fluctuation, the tank body 2
The vaporized fuel gas inside is discharged to the evaporation tube 3 and guided from the evaporation tube 3 to the canister 4.

The casing of the fuel cutoff device 1 is composed of a case upper 7 having an evaporation passage 5, a case lower 10 having a valve housing wall 8 and a valve seat 9, and a cap 11 attached to the lower end of the case lower 10. The float valve 12, which is a valve for shutting off the fuel, is housed inside.

The case upper 7 is made of a resin material, such as polyethylene, which is the same material as that of the tank main body 2. A flange portion 6 for welding is provided on the outer periphery of the base portion 13, and the evaporation tube 3 is connected to the upper surface thereof. The outlet 14 is extended. The evaporation passage 5 is provided from the outlet 14 to the base portion 13. The horizontal passage 15 on the tip side of the outlet 14 and the vertical passage 1 on the base portion 13 side.
6 and 6. The lower end of the vertical passage 16 is a large diameter portion 17 having a larger diameter than the general portion, and
A hollow portion 18 is formed in the base portion 13 and expands horizontally from the upper end of the large diameter portion 17 in a flange shape. Reference numeral 19 in the figure denotes a reinforcing rib integrally formed on the upper surface side of the base portion 13.

The case upper 7 is formed in advance by injection molding or the like before forming the case lower 10.

On the other hand, the case lower 10 is made of a resin material different from that of the tank body 2, for example, polyacetal or the like, and the seal portion 12a of the float valve 12 abuts on the center of the upper wall portion of the cylindrical valve housing wall 8 with a lid. 9 has a schematic structure. When the case lower 10 is formed, the previously formed case upper 7 is set in the molding die, and the insert pin is fitted into the vertical passage 16 of the case upper 7. In this state, the resin is placed in the molding die. Fill the material. At this time, the resin material is filled in the cavity 18 through the gap between the large diameter portion 17 and the insert pin, and the case upper 7 and the case lower 10 are insert-molded. The valve seat 9 on the case lower 10 side is formed by an insert pin. Since the insert pin is fitted into the vertical passage 16 which forms a part of the evaporation passage 5 at the time of setting, the valve seat 9 and the evaporation passage 5 are formed coaxially. Will be done.

The cap 11 is made of the same resin material as that of the case lower 10. The case lower 10 is insert-molded with the case upper 7 to accommodate the float valve 12, and then the clip is attached to the lower end of the case lower 10. Will be stopped. In the figure, 20 is a cap 1.
Reference numeral 21 is a communication hole formed in 1, and 21 is an elastic member interposed between the bottom portion and the cap 11 so that the float valve 12 can also function as a so-called rollover valve.

In the fuel cutoff device thus constructed, the case lower 10 and the cap 11 are the tank main body 2
The flange portion 6 of the case upper 7 is welded to the peripheral portion of the mounting hole 22 in this state. At this time, since the case upper 7 is made of the same resin material as that of the tank body 2, the welding is easily and reliably performed.

Further, the case upper 7 and the case lower 10
Are formed of resin materials having different swelling amounts, but since the resin material on the case lower 10 side protrudes into the cavity 18 of the case upper 7 by insert molding, the case upper 7 and the case lower 10 are separated from each other. It is firmly bonded and its bond strength does not decrease even after use over time. Furthermore, since the valve seat 9 is formed coaxially by inserting the insert pin into the evaporation passage 5 (vertical passage 16) during insert molding, the valve seat 9 is accurately aligned with the evaporation passage 5. Therefore, the passage from the evaporation passage 5 to the valve seat 9 is always secured stably.

[0019]

As described above, according to the present invention, since the case upper and the case lower are integrated by insert molding at the stage of molding, the bonding strength between them is extremely high, and the center of the evaporation passage and the valve seat is Since the centers of the two parts are exactly aligned with each other in order to match each other in the molding stage, it becomes possible to reliably secure the passage from the evaporation passage to the valve seat.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is an overall schematic diagram showing the same embodiment.

FIG. 3 is a plan view showing the same embodiment.

[Explanation of symbols]

1 ... Fuel cutoff device, 5 ... Evaporation passage, 7 ... Case upper, 8 ... Valve housing wall, 9 ... Valve seat, 10 ... Case lower.

Claims (1)

[Claims] 1. A case upper having an evaporation passage,
In a fuel cutoff device for a fuel tank in which a valve housing wall and a case lower including a valve seat are made of different resin materials, the case upper and the case lower are insert-molded with the evaporation passage and the valve seat being coaxial. Fuel cutoff device for fuel tank.