JPH04356228A - Vaporized fuel processing apparatus for fuel tank - Google Patents

Abstract

PURPOSE:To increase the degree of freedom of layout in a vehicle by enabling the disposition of a fuel shut-off valve to be set low. CONSTITUTION:The inside of a casing 20 of a fuel shut-off valve 107 is defined into an upper chamber 22 and lower chamber 23. A first float 26 is received in the lower chamber 23 and the upper chamber 22 receives a second float 29 while a vent tube 2 and sub-vent tube 3 are connected to the upper chamber 22. Thus, in oiling, the first float 26 closes a communicating hole 24 to enclose an upper space in a tank body 4, and after a liquid level in a filler tube 5 rises to the upper end of the tube, the second float 29 closes a communicating hole 28 to shut off the communication between the filler tube 5 and a canister 1. Further, A screen wall 31 is provided on the upper position of the communicating hole 24. By mounting the second float 29 on the uper surface of the screen wall, evaporated fuel escaping from the lower chamber 23 to the upper chamber 22 is adapted not to directly lift the second float 29.

Description

[Detailed description of the invention]

0001

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

0002

2. Description of the Related Art As this type of evaporated fuel processing apparatus, one disclosed in Japanese Utility Model Application Laid-Open No. 1-131619 has been devised.

As shown in FIG. 7, this evaporated fuel processing apparatus is constructed such that a canister 1 for adsorbing evaporated fuel is connected to a vent tube 2 and a sub-vent tube 3 to form an upper space of a tank body 4 and an upper end of a filler tube 5. The basic configuration is such that the evaporated fuel inside the tank body 4 and filler tube 5 is discharged to the canister 1 side during fuel refueling. A fuel cutoff valve 7 is interposed which has a float 6 that floats up due to the inflow of fuel from the main body 4 and closes the passage 2a of the vent tube 2 on the side of the canister 1. The fuel cutoff valve 7 is disposed outside the tank body 4 so as to be at approximately the same height as the upper end of the filler tube 5, and when refueling, the float 6 is placed until the liquid level in the filler tube 5 reaches its upper end.
is designed so that it 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 is closed.
This is to prevent fuel from flowing out to the side, but if the float 6 blocks the passage 2a before the liquid level in the filler tube 5 reaches its upper end, the gas in the filler tube 5 will escape. Therefore, the auto-stop sensor 9 of the refueling gun 8 becomes inoperable due to the above-mentioned condition.In order to eliminate such malfunction of the auto-stop sensor 9, the above-mentioned arrangement is adopted. In addition, in FIG. 7, reference numeral 10 indicates a passage 2a in conjunction with the insertion and removal operation of the refueling gun 8 into the filler tube 5.
11 is a canister that processes evaporated fuel generated within the tank body 4 when not refueling, and 12 is an evaporation tube that communicates the upper space of the tank body 4 with the canister 11.

0004

However, in the case of the conventional evaporative fuel processing device described above, in order to eliminate malfunction of the auto-stop sensor 9, the fuel cutoff valve 7 is set at approximately the same height as the upper end of the filler tube 5. This is a factor that reduces the degree of freedom in the layout of the vehicle.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a fuel tank evaporative fuel treatment system that allows the arrangement of the fuel cutoff valve to be set at a low position, thereby providing a high degree of freedom in the layout of a vehicle.

[0006]

[Means for Solving the Problems] As a means for solving the above-mentioned problems, the present invention provides a confluence section between a vent tube and a sub-vent tube that communicates the upper space of a tank body and the vicinity of the upper end of a filler tube with a canister. A fuel cutoff valve is provided in the tank body, and the inside of the casing of the fuel cutoff valve is divided into an upper chamber and a lower chamber, and a communicating hole with the upper chamber that floats up as the liquid level of the fuel in the tank body rises is formed in the lower chamber. while accommodating a first float that blocks the upper chamber, a vent tube and a sub-vent tube are respectively connected to the upper chamber, and
A second float is accommodated that floats as the liquid level of the fuel flowing in from the sub-vent tube rises and closes the connection hole with the vent tube, and a shielding wall is provided above the communication hole in the upper chamber to cover the second float. The second float was placed on the wall.

[0007]

[Operation] When fuel supply is started, the evaporated fuel inside the tank body and filler tube passes through the inside of the fuel cutoff valve and is discharged into the canister. At this time, the vaporized fuel that has passed through the communication hole from the lower chamber of the fuel cutoff valve does not directly hit the lower surface of the first float because there is a shielding wall above it. When the liquid level of the fuel within the tank body reaches a predetermined height, the first float of the fuel cutoff valve floats to close the communication hole and seal the upper space within the tank body. At this time, since the subvent tube communicates with the canister side in the upper chamber of the fuel cutoff valve, the fuel liquid level in the filler tube rises to the upper end. If refueling continues, the fuel in the filler tube will flow into the upper chamber of the fuel cutoff valve through the sub-vent tube, and the second float will float up and close the connection hole with the vent tube, closing the canister. Prevent fuel from flowing to the side.

[0008]

[Embodiment] Next, an embodiment of the present invention will be described based on FIGS. 1 to 6. Note that the same reference numerals are used for the same parts as in the conventional one shown in FIG.

First, an overview of the entire fuel tank will be explained.

In FIG. 3, reference numeral 4 denotes a tank body of a fuel tank, and an evaporated fuel processing device A according to the present invention is disposed in the upper part of this tank body 4. 5 is a filler tube for supplying fuel to the tank body 4;
A shutter 14 is provided at the upper end of the filler tube 5 to prevent evaporated fuel from being directly discharged into the atmosphere when the filler cap 13 is opened, and a shutter 14 is provided to prevent the fuel vapor from being directly discharged into the atmosphere when the filler cap 13 is opened. A seal member 15 is provided to prevent evaporated fuel from being discharged into the atmosphere from the gap.

Reference numeral 1 denotes a canister for adsorbing and treating evaporated fuel, and this canister 1 includes a evaporated fuel processing device A according to the present invention that processes evaporated fuel generated within the tank body 4 during refueling, and a It is shared with another evaporated fuel processing device B that processes evaporated fuel generated within the tank body 4 at other times. That is, the vent tube 2 and the evaporative tube 12, which communicate with the upper space within the tank body 4, merge at the valve chamber 16 provided in contact with the outer periphery of the upper end of the filler tube 5, and this valve chamber 16 and the canister 1 are connected together. When the switching valve 18 provided in the valve chamber 16 operates in conjunction with the opening/closing operation of the shutter 14, either the vent tube 2 or the evaporative tube 12 is connected to the canister 1. It is designed to communicate with Note that when the shutter 14 is opened during refueling, the vent tube 2 side communicates with the canister 1.

Further, a fuel cutoff valve 107, which is a main part of the present invention, is provided at the end of the vent tube 2 on the tank body 4 side. A sub-vent tube 3 that communicates the vicinity with the canister 1 is connected to the confluence. The fuel cutoff valve 107 is fixedly installed on the upper wall of the tank body 4, and its lower end protrudes into the upper space within the tank body 4 by a predetermined amount.

Reference numeral 19 denotes a fuel cutoff valve provided at the end of the evaporative tube 12 on the side of the tank body 4. This fuel cutoff valve 19 closes the evaporative tube 12 when the liquid level changes due to the tilt of the vehicle or the like. Next, the fuel cutoff valve 107 will be described in detail.

In FIGS. 1 and 2, reference numeral 20 denotes a casing of the fuel cutoff valve 107, and the interior of the casing 20 is defined by a partition wall 21 into an upper chamber 22 and a lower chamber 23. As shown in FIG. A communication hole 24 is formed in the center of the partition wall 21 to communicate the only communication between the upper chamber 22 and the lower chamber 23, and gas can enter and exit between the upper chamber 22 and the lower chamber 23 through this communication hole 24. It has become. The lower chamber 23 communicates with the inside of the tank body 4 through a communication hole 25, and a first float 26 formed in a hemispherical shape and made of a material whose specific gravity is lighter than that of the fuel is accommodated therein. When the liquid level of the fuel in the tank body 4 reaches a predetermined height during refueling, the first float 26 rises due to buoyancy and its upper surface closes the communication hole 24, thereby filling the upper space in the tank body 4. It is designed to be sealed tightly.

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, and a connecting hole 28 with the vent tube 2 is provided in the center of the upper wall constituting the upper chamber 22. is open. Further, a substantially disc-shaped shielding wall 31 is provided in the upper chamber 22 in parallel with the partition wall 21, and the outer peripheral portion of the shielding wall 31 is supported by a plurality of beams 32 on the inner peripheral wall of the upper chamber 22. has been done. The shielding wall 31 is located above the communication hole 24 of the partition wall, so that the evaporated fuel that has passed through the communication hole 24 from the lower chamber 23 side does not directly blow upward, but passes through the opening 33 between the beams 32 and 32. After that, it exits upward. Further, on the upper surface of the shielding wall 31, a second float 29 formed in a hemispherical shape and made of a material having a specific gravity heavier than the fuel is mounted via a spring 30.
The outer diameter of the bottom surface of the second float 29 is set to be slightly smaller than the outer diameter of the shielding wall 31, so that the evaporated fuel passing through the opening 33 from below does not directly hit the bottom surface of the second float 29. There is. The second float 29 is connected to the connection hole 2 in the normal state.
8 is open, but with the first float 26 blocking the communication hole 24, fuel flows from the sub vent tube 3 to the upper chamber 2.
When it flows into the inside of the connecting hole 2, a buoyant force acts in addition to the force of the spring 30, causing it to rise, and the upper surface of the connecting hole 2
8 will be occluded.

In the above configuration, when the fuel gun 8 is inserted into the upper end of the filler tube 5 to start refueling the tank body 4 as shown in FIG. Low surface fuel cutoff valve 107
Since both the first float 26 and the second float 29 are in a lowered state, the evaporated fuel in the upper space of the tank body 4 flows into the fuel cutoff valve 10, as shown by the arrows in FIGS.
The evaporated fuel in the filler tube 5 enters the upper chamber 22 from the lower chamber 23 of No. It passes sequentially through the supply/discharge tube 17 and is discharged into the canister 1 . When the evaporated fuel that has passed through the communication hole 24 passes through the upper chamber 22, the evaporated fuel that has passed through the communication hole 24 once goes around the outer circumferential direction of the shielding wall 31 as shown in FIG. 2 float 29
It exits into the connection hole 28 along the spherical shape of the upper surface. In this way, the evaporated fuel flows smoothly into the connection hole 28 without hitting the lower surface of the second float 29, so there is no problem in which the second float 29 blocks the connection hole 28 due to the evaporated fuel blown up from the lower chamber 23 side. It won't happen.

Further, when the liquid level of the fuel in the tank body 4 reaches a predetermined height, the fuel cutoff valve 1 is opened from the communication hole 25.
Fuel flows into the lower chamber 23 of 07, as shown in FIG.
The first float 26 floats up and closes 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, and the evaporated fuel in the filler tube 5 continues until the liquid level reaches the vicinity of its upper end. sub vent tube 3
The fuel continues to be discharged into the canister 1 through the upper chamber 22 of the fuel cutoff valve 107, the connection hole 28, the vent tube 2, etc. When the liquid level within the filler tube 5 reaches the vicinity of its upper end, this is sensed by the auto-stop sensor 9 of the refueling gun 8, and refueling is stopped.

Furthermore, when the auto-stop sensor 9 is out of order or when additional refueling is performed, fuel passes through the sub-vent tube 3 connected to the vicinity of the upper end of the filler tube 5 and enters the upper chamber of the fuel cut-off valve 107. 22. When the liquid level of the fuel in the upper chamber 22 increases in this way, the second float 29 floats up and closes the connection hole 28, as shown in FIG.
This will cut off communication with. This prevents fuel from flowing out from the sub-vent tube 3 to the canister 1. When refueling is completed in this way and the fuel in the tank body 4 is used, the liquid level in the tank body 4 decreases and the first
The float 26 descends to open the communication hole 24, and the upper chamber 2
The fuel in the tank 2 and the subvent tube 3 is supplied into the tank body 4 through the communication hole 24.

Furthermore, when the vehicle rolls over, the first float 26 floats due to its specific gravity, but the second float 26 descends due to its own weight and the force of the spring 30, as shown in FIG. Since the connection hole 28 is closed, fuel will not flow out to the canister 1 side through the vent tube 2.

[0020]

As described above, according to the present invention, the inside of the casing of the fuel cutoff valve is divided into an upper chamber and a lower chamber, and the lower chamber is filled with floating fuel as the liquid level rises in the tank body. A first float that closes the communication hole with the upper chamber is housed, and the vent tube and the sub-vent tube are connected to the upper chamber, and the float rises as the liquid level of the fuel flowing in from the sub-vent tube rises to connect with the vent tube. Since the second float that closes the connection hole is accommodated, when refueling, the upper space in the tank body is sealed by the first float and the liquid level in the filler tube rises to its upper end, and then the second float is inserted. Communication between the filler tube and the canister is now cut off by the float, and even if the fuel cutoff valve is placed at a position lower than the upper end of the filler tube, the problem of gas in the filler tube not being able to escape during refueling will not occur. For this reason, it becomes possible to set the fuel cutoff valve at a low value, increasing the degree of freedom in the layout of the vehicle. Furthermore, since a shielding wall is provided above the communication hole in the upper chamber and the second float is placed on the shielding wall, the evaporated fuel passing through the communication hole from the tank body side can be transferred to the second float. Problems such as pushing up from below and blocking the connection hole with the vent tube will no longer occur.

[Brief explanation of drawings]

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

FIG. 2 is a sectional view taken along line CC in FIG. 1;

FIG. 3 is an overall schematic diagram showing an embodiment of the present invention.

FIG. 4 is a sectional view showing the same embodiment.

FIG. 5 is a sectional view showing the same embodiment.

FIG. 6 is a sectional view showing the same embodiment.

FIG. 7 is a sectional view showing a conventional technique.

[Explanation 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...Connection hole, 29...
Second float, 31...shielding wall, 107... fuel cutoff valve.

Claims (1)

[Claims] Claim 1: A fuel cutoff valve is provided at the confluence of a vent tube and a subvent tube that communicate the upper space of the tank body and the vicinity of the upper end of the filler tube with the canister, and the inside of the casing of the fuel cutoff valve is defined as an upper chamber. A first chamber is defined in the lower chamber, and in the lower chamber, the first tube floats up as the liquid level of the fuel in the tank body rises and blocks the communication hole with the upper chamber.
A second float that accommodates the float and connects a vent tube and a sub-vent tube to the upper chamber, respectively, and floats as the liquid level of the fuel flowing from the sub-vent tube rises to close the connection hole with the vent tube. An evaporated fuel processing device for a fuel tank, further comprising: a shielding wall provided above the communication hole in the upper chamber, and the second float placed on the shielding wall.