JP2616599B2 - Fuel tank evaporative fuel treatment system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel vapor processing apparatus for processing fuel vapor generated in a fuel tank during refueling.

[0002]

2. Description of the Related Art Conventionally, as this type of evaporative fuel processing apparatus, an apparatus shown in Japanese Utility Model Laid-Open Publication No. 1-131619 has been proposed.

As shown in FIG. 6, this evaporative fuel processing apparatus uses a vent tube 2 and a sub-vent tube 3 for an upper space of a tank body 4 and an upper end of a filler tube 5 for a canister 1 for adsorbing evaporative fuel. Are connected to each other so that the fuel vapor inside the tank body 4 and the filler tube 5 is discharged to the canister 1 when fuel is supplied. A fuel cutoff valve 7 having a float 6 that floats by the inflow of fuel from the main body 4 and closes the passage 2 a of the vent tube 2 on the canister 1 side is interposed. The fuel shut-off valve 7 is disposed outside the tank body 4 so as to be substantially at the same height as the upper end of the filler tube 5, and when the fuel is supplied, the float 6 is held until the liquid level in the filler tube 5 reaches the upper end.
Does not block the passage 2a. When the liquid level in the tank body 4 reaches a predetermined height due to fuel supply and the fuel in the tank body 4 flows in through the passage 2b, the float 6 closes the passage 2a and the canister 1
If the float 6 blocks the passage 2a before the liquid level in the filler tube 5 reaches the upper end thereof, the gas in the filler tube 5 escapes. As a result, the automatic stop sensor 9 of the refueling gun 8 does not operate, so that the above-described arrangement is adopted in order to eliminate such a malfunction of the automatic stop sensor 9. In FIG. 6, reference numeral 10 denotes a passage 2a in conjunction with the operation of inserting and removing the refueling gun 8 from the filler tube 5.
Numeral 11 denotes a canister for processing evaporated fuel generated in the tank main body 4 at times other than refueling, and 12 denotes an evaporative tube for communicating the upper space of the tank main body 4 with the canister 11. .

[0004]

However, in the case of the above-described conventional evaporative fuel treatment apparatus, the fuel cutoff valve 7 is set to be substantially flush with the upper end of the filler tube 5 in order to eliminate the malfunction of the automatic stop sensor 9. This is a factor that narrows the layout of the vehicle.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a fuel tank evaporative fuel processing apparatus having a high degree of freedom in layout of a vehicle by allowing the fuel cutoff valve to be set at a low position.

[0006]

According to the present invention, as a means for solving the above-mentioned problems, a vent tube and a sub-vent tube are connected to each other so that the upper space of the tank body and the vicinity of the upper end of the filler tube communicate with the canister. In a fuel tank evaporative fuel treatment apparatus provided with a fuel cut-off valve in a portion, an inside of a casing of the fuel cut-off valve is defined as an upper chamber and a lower chamber, and the lower chamber has a liquid level of fuel in a tank body. While the first float that floats up to close the communication hole with the upper chamber is accommodated, a vent tube and a sub vent tube are respectively connected to the upper chamber, and the level of the fuel flowing from the sub vent tube rises. To accommodate the second float that floats to close the communication hole with the vent tube.

[0007]

When the fuel supply is started, the fuel vapor inside the tank body and the filler tube is discharged to the canister through the vent tube and the sub vent tube. When the liquid level of the fuel in the tank body reaches a predetermined height in this way, the first float of the fuel cutoff valve floats, closing the communication hole between the lower chamber and the upper chamber, and sealing the upper space in the tank body. . At this time, since the sub vent tube communicates with the canister side in the upper chamber of the fuel cutoff valve, the fuel level in the filler tube rises to the upper end. Here, if the refueling is continued, the fuel in the filler tube flows into the upper chamber of the fuel cutoff valve through the sub vent tube, and the second float floats and closes the communication hole with the vent tube in the upper chamber. To prevent the fuel from flowing out to the canister side.

[0008]

Next, an embodiment of the present invention will be described with reference to FIGS. It is to be noted that the same reference numerals are used for the same portions as the conventional one shown in FIG.

First, an outline of the entire fuel tank will be described.

In FIG. 2, reference numeral 4 denotes a tank main body of a fuel tank, on which an evaporative fuel processing apparatus A according to the present invention is disposed. 5 is a filler tube for supplying fuel to the tank body 4,
At the upper end of the filler tube 5, a shutter 14 for preventing the fuel vapor from being directly discharged to the atmosphere when the filler cap 13 is opened, and a suction gun 8 when the refueling gun 8 is inserted. Is provided with a seal member 15 for preventing the evaporated fuel from being discharged to the atmosphere through the gap.

Reference numeral 1 denotes a canister for adsorbing the evaporated fuel. The canister 1 includes an evaporative fuel processing apparatus A according to the present invention for processing the evaporative fuel generated in the tank body 4 at the time of refueling, and a canister at the time of refueling. At other times, the fuel tank is shared with another evaporated fuel processing apparatus B for processing the evaporated fuel generated in the tank body 4. That is, the vent tube 2 and the evaporator tube 12 communicating with the upper space in the tank body 4 join at the valve chamber 16 provided in contact with the outer periphery of the upper end portion of the filler tube 5, and the valve chamber 16 and the canister 1 are connected. When the switching valve 18 provided in the valve chamber 16 is operated in conjunction with the opening and closing operation of the shutter 14, one of the vent tube 2 and the evaporation tube 12 is connected to the canister 1. It has come to communicate with. When the shutter 14 is opened during refueling, the vent tube 2 side communicates with the canister 1.

A fuel shut-off valve 107 which is an essential part of the present invention is provided at an end of the vent tube 2 on the tank body 4 side. The fuel shut-off valve 107 has an upper end in the filler tube 5. A sub-vent tube 3 for communicating the vicinity with the canister 1 is joined and connected. The fuel cutoff valve 107 is fixedly installed on the upper wall portion of the tank main body 4, and has a lower end projecting a predetermined amount into an upper space in the tank main body 4.

Reference numeral 19 denotes a fuel cutoff valve provided at an end of the evaporative tube 12 on the tank body 4 side. The fuel cutoff valve 19 is provided when the liquid level fluctuates due to the inclination of the vehicle or the like. The fuel cutoff valve 107 is closed to prevent the fuel from flowing out of the evaporation tube 12 to the outside. Next, the fuel cutoff valve 107 will be described in detail.

In FIGS. 1 and 3 to 5, reference numeral 20 denotes
The casing of the fuel cutoff valve 107 has an interior defined by a partition wall 21 into an upper chamber 22 and a lower chamber 23. An upper chamber 22 is provided on the partition wall 21.
And a communication hole 24 that solely communicates with the lower chamber 23,
Gas flows between the upper chamber 22 and the lower chamber 23 through the communication hole 24. Lower chamber 23
Communicates with the inside of the tank body 4 through the communication hole 25,
A first float 26 made of a material having a specific gravity lower than that of the fuel is accommodated therein. When the liquid level of the fuel in the tank body 4 reaches a predetermined height at the time of refueling, the first float 26 rises by buoyancy, and the seal portion 27 protruding from the upper surface closes the communication hole 24, and This seals the upper space in the tank body 4.

On the other hand, a vent tube 2 and a sub vent tube 3 are connected to the upper chamber 22 of the casing 20 in communication with each other. A communication hole 28 with the vent tube 2 is formed at the center of the upper wall constituting the upper chamber 22. It is open. In the upper chamber 22, a second float 29 formed of a material having a specific gravity greater than that of the fuel is accommodated in a state where the second float 29 is urged upward by a spring 30. 2nd float 29
In the normal state, the communication hole 28 is opened. However, when the fuel flows from the sub vent tube 3 into the upper chamber 22 with the first float 26 closing the communication hole 24, the force of the spring 30 is added. The buoyancy is applied and the ascending portion rises, and the seal portion 31 protruding from the upper surface thereof closes the communication hole 28. A notch 32 is provided from the center of the lower surface of the second float 29 to a part of the side wall, so that the upper space and the lower space of the second float 29 communicate with each other through the notch 32. .

In the above configuration, as shown in FIG. 2, when the refueling gun 8 is inserted into the upper end of the filler tube 5 and refueling of the tank body 4 is started, at the beginning of refueling, the fuel liquid in the tank body 4 is initially started. Fuel cutoff valve 107
Since both the first float 26 and the second float 29 are in a lowered state, as shown by the arrows in FIGS.
07 from the lower chamber 23 to the upper chamber 22 through the communication hole 24, the fuel vapor in the filler tube 5 enters the upper chamber 22 from the sub-vent tube 3, and the communication hole 28, the vent tube 2, It is discharged to the canister 1 through the supply / discharge tube 17 in order.

When the liquid level of the fuel in the tank body 4 reaches a predetermined level, the fuel flows from the communication hole 25 into the lower chamber 23 of the fuel cutoff valve 107, and as shown in FIG. Rises to close the communication hole 24. As a result, the upper space in the tank body 4 is sealed, so that only the liquid level in the filler tube 5 rises thereafter, and the fuel vapor in the filler tube 5 remains until the liquid level reaches near the upper end thereof. The gas is continuously discharged from the sub vent tube 3 to the canister 1 through the upper chamber 22, the communication hole 28, the vent tube 2, and the like of the fuel cutoff valve 107. When the liquid level in the filler tube 5 reaches near the upper end thereof, the fact is detected by the automatic stop sensor 9 of the refueling gun 8 and the refueling is stopped.

When the auto stop sensor 9 is out of order or additional fuel is supplied, fuel flows through the sub vent tube 3 connected near the upper end of the filler tube 5 to the upper chamber of the fuel cutoff valve 107. 22. When the liquid level of the fuel in the upper chamber 22 rises in this manner, as shown in FIG. 4, the second float 29 floats and closes the communication hole 28, and the upper chamber 22 and the sub vent tube 3
Communication with the user is cut off. As a result, the outflow of fuel from the sub vent tube 3 to the canister 1 is prevented. When the refueling is completed and the fuel in the tank main body 4 is used, the first level is lowered along with the decrease in the liquid level in the tank main body 4.
The float 26 descends to open the communication hole 24 and the upper chamber 2
The fuel in 2 and the sub-vent tube 3 is supplied into the tank body 4 from the communication hole 24.

Further, when the vehicle rolls over, as shown in FIG. 5, the first float 26 floats due to the specific gravity, but the second float 26 descends due to its own weight and the force of the spring 30 to communicate with each other. In order to close the hole 28, fuel passes through the vent tube 2 and the canister 1
No more outflows to the side.

[0020]

As described above, according to the present invention, when the fuel is supplied, the upper space in the tank body is sealed by the first float, and the liquid level in the filler tube rises to the upper end thereof. Because the float blocks the communication between the filler tube and the canister,
Even if the fuel shut-off valve is arranged at a position lower than the upper end of the filler tube, the problem that the gas in the filler tube does not escape during refueling does not occur. For this reason, the fuel cutoff valve can be set low, and the degree of freedom in the layout of the vehicle is increased.

[Brief description of the drawings]

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

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

FIG. 3 is a sectional view showing the embodiment.

FIG. 4 is a sectional view showing the embodiment.

FIG. 5 is a sectional view showing the embodiment.

FIG. 6 is a sectional view showing a conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Canister, 2 ... Vent tube, 3 ... Sub vent tube, 4 ... Tank body, 5 ... Filler tube,
20: casing, 22: upper chamber, 23: lower chamber, 24
... communication hole, 26 ... first float, 28 ... communication hole, 29 ...
Second float, 107: fuel cutoff valve.

Claims (1)

(57) [Claims] 1. An evaporative fuel processing apparatus for a fuel tank, wherein a fuel cut-off valve is provided at a junction of a vent tube and a sub-vent tube for communicating an upper space of a tank body and an upper end portion of a filler tube with a canister, respectively.
The casing of the fuel cutoff valve is divided into an upper chamber and a lower chamber, and a first float that floats due to a rise in the fuel level in the tank body and closes a communication hole with the upper chamber is defined in the lower chamber. On the other hand, a vent tube and a sub-vent tube are respectively connected to the upper chamber, and a second float that floats due to a rise in the level of fuel flowing from the sub-vent tube and closes a communication hole with the vent tube is housed in the upper chamber. An evaporated fuel processing apparatus for a fuel tank, characterized in that: