JPH04201723A - Fuel cut-off of fuel tank - Google Patents

Abstract

PURPOSE:To surely prevent sticking of a float by providing a through hole in the vertical direction, through a float, while also providing a valve body on the lower end of the through hole, and opening the valve body by a pushing up projection when the float descends. CONSTITUTION:This fuel cut-off has an outlet 6 extendedly provided on the upper end of a casing 3, and evaporated fuel gas generated in a tank main body 4 is discharged from this outlet. Through holes 7, 8 are respectively formed on the side wall and the bottom wall of the casing 3, and a float 5 is stored in the casing 3. A through hole 10 for providing communication in the vertical direction is formed in the axial core portion of the float 5. The upper end portion of the through hole 10 is connected to a gas discharging hole 2 by a tube 11. A spring 12 and a ball 13 are stored in the through hole 10, and a valve seat 14 is fixed on the bottom end of the through hole. When the float 5 descends by its dead weight the ball 13 is pushed upward by a pushing up projection 15 to open the aperture 14a of the valve seat 14.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a fuel cutoff device for a fuel tank mounted on a vehicle such as an automobile.

BACKGROUND OF THE INVENTION Some automobile fuel tanks are known to be equipped with a fuel cutoff device to prevent fuel from flowing out from the evaporative tube due to fluctuations in the fuel level within the tank body. Generally, as shown in FIG. 4, this fuel cutoff device has a casing 3 equipped with a gas discharge hole 2 that communicates with an evaporative tube 1 and is disposed in the upper part of a tank body 4. It has a structure in which a float 5 that can block the discharge hole 2 is housed, and in the figure E and F
When fuel A flows into the casing 3 due to fluctuations in the fuel liquid level as shown in the figure, the gas discharge hole 2 is closed by the floating of the float 5.

However, in the case of such a fuel cutoff device, when the float 5 blocks the gas discharge hole 2 due to fluctuations in the fuel level in the tank body 4 and the gas pressure in the tank body 4 increases in this state, the inside of the casing 3 There is a concern that the float 5 will stick to the gas exhaust hole 2 even after the fuel A has flowed out of the gas exhaust hole 2, which is the so-called stick phenomenon. This was a contributing factor to the increase.

To deal with this problem, conventional methods have been to provide a relief valve in the casing, such as the one shown in Japanese Utility Model Application No. 62-75278, so that when the float closes the gas discharge hole, the inside of the tank body is closed. A fuel cut-off device has been developed in which a relief valve opens when the gas pressure exceeds a set value, allowing the gas in the tank body to escape to the evaporative tube, thereby avoiding stick.

Problems to be Solved by the Invention In the case of the above-mentioned conventional fuel cutoff device, the relief valve is for avoiding the stick of the float, so the opening pressure is within the tank body where the float makes strong contact with the gas discharge hole. It is necessary to set the pressure lower than the gas pressure (hereinafter referred to as stick pressure).

Therefore, if the stick pressure of the float is set low, the opening pressure of the relief valve will also be lowered, and there is a risk that the relief valve will open when the float normally blocks the gas exhaust hole due to fuel flowing into the casing. come. Therefore, the need to set the stake pressure as high as possible has been solved by increasing the weight of the float, which results in an increase in the size and weight of the float, so this is not a fundamental solution to the increase in vehicle weight. There wasn't. For these reasons, in the conventional fuel cutoff device described above, it is extremely difficult to appropriately set the relief valve opening pressure and stake pressure.

Therefore, the present invention aims to provide a fuel cutoff device for a fuel tank that can reliably prevent the float from sticking without increasing the size of the device.

Means for Solving the Problems As a means for solving the above-mentioned problems, the present invention provides a method in which when fuel flows into the casing disposed in the upper part of the tank body, the gas discharge hole provided in the casing is blocked. In the fuel cutoff device for a fuel tank, the casing accommodates a float that floats due to the inflow of fuel,
A communication hole communicating in the vertical direction is provided in the float, and the communication hole and the gas discharge hole are connected with an expandable tube, and a valve seat is provided at the lower end of the communication hole,
A valve body that closes the valve seat from the upper side is provided, and a push-up protrusion that pushes up the valve body and opens the valve seat when the float is lowered is provided on the casing.

When no fuel is flowing into the working casing,
Since the float is lowered by its own weight, the valve body is opened by the pushing-up protrusion, and the evaporated fuel gas in the tank body passes through the communication hole and the tube and is discharged from the gas discharge hole. When fuel flows into the casing, the float rises while compressing the tube, causing the valve body and the push-up protrusion to separate and the valve body to close the valve seat.

In addition, since the valve seat provided at the lower end of the communication hole is closed from the upper side by the valve body, even if a situation occurs where the float does not descend immediately after the fuel is discharged from the casing, the tank When the gas pressure inside the tank body becomes greater than the set value, the gas pressure inside the tank body causes the valve body to open the valve seat and the float to descend.

EXAMPLE Hereinafter, an example of the present invention will be described based on FIGS. 1 to 3. Note that the same reference numerals are used for the same parts as those shown in FIG.

In FIGS. 1 to 3, 3 is a casing of a fuel cutoff device made of a resin material, and this casing 3 is disposed on the upper part of the tank body 4 and is connected to the evaporative tube 1 at its upper end. An outlet 6 is extended, and the evaporated fuel gas generated within the tank body 4 is guided from the gas discharge hole 2 of the outlet 6 through the evaporative tube 1 to a canister (not shown). Communication holes 7.8 are formed in the side wall and lower wall of the casing 3, respectively, and when the fuel level in the tank body 4 fluctuates when the vehicle turns or tilts, the fuel flows through the communication holes 7.8 into the tank body. The fuel A in the casing 3 flows into the casing 3.

Reference numeral 5 denotes a float housed inside the casing 3 with its lower surface supported by a spring 9. When the fuel A flows into the casing 3, the float 5 combines its own buoyancy with that of the spring 9. rise by force. A communication hole 10 that communicates in the vertical direction is formed in the axial center of the float 5, and the upper end of this communication hole 10 is connected to a bellows-shaped portion 11.
A stretchable resin or rubber tube 1 with a
1 is connected to the gas discharge hole 2 of the casing 3. Therefore, when the float 5 rises due to its own buoyancy and the force of the spring 9, the bellows-shaped portion 11a deforms and the tube 11 contracts in the axial direction. Also,
A spring 12 and a ball 13 serving as a valve body are housed inside the communication hole 10, and a valve seat 14 is fixed to the lower end thereof.

The ball 13 housed in the communication hole 10 closes the opening 14a of the valve seat 14 from the upper side by its own weight and the force of the spring 12, thereby cutting off communication between the inside of the tank body 4 and the gas discharge hole 2.

Reference numeral 15 denotes a push-up protrusion formed at the center of the lower surface of the casing 3. When the float 5 descends due to its own weight, the push-up protrusion 15 is loosely inserted into the opening 14a of the valve seat 14. Push the ball 13 upward with the tip to open the opening 14a of the valve seat 14,
The inside of the tank body 4 and the gas discharge hole 2 are communicated with each other.

With the above configuration, under normal conditions where the fuel level in the tank body 4 does not fluctuate, the float 5 descends due to its own weight and the ball 13 is pushed against the push-up protrusion 15, as shown in FIG. The opening 14a of the valve seat 14 is in an open state. Therefore, the evaporated fuel gas generated within the tank body 4 passes through the communication hole 7.8, the valve seat 14, the communication hole 10, the tube 11, the gas discharge hole 2, and the evaporative tube 1 in this order and is discharged to the outside.

When the fuel A flows into the casing 3 from this state due to fluctuations in the fuel level within the tank body 4, the float floats while compressing the bellows-shaped portion 11a of the tube 11, as shown in FIGS. 2 and 3 sequentially. 5 rises, the ball 13 and the push-up protrusion 15 separate from each other, and the ball 13 pushes against the valve seat 14 due to its own weight and the force of the spring 12.
The opening 14a of the opening 14a is closed.

In this state, if the gas pressure inside the tank body 4 increases due to a rise in temperature, etc., even after the fuel A returns from the casing 3 to the tank body 4, there will be a difference in gas pressure between the inside of the tank body 4 and the gas discharge hole 2. However, if the gas pressure inside the tank body 4 rises above a predetermined value, the force of the gas pressure inside the tank body 4 will cause the float 5 to descend more easily.
Ball 1 overcomes the resultant force of the own weight of ball 3 and the force of spring 12.
3 and opens the opening 14a of the valve seat 14, the gas pressure inside the tank body 4 decreases and the float 5 falls down reliably. As a result, the stick of the float 5 is avoided.

Effects of the Invention As described above, the present invention provides a communication hole that communicates in the vertical direction in a float housed in a casing, connects the communication hole and a gas discharge hole with an extensible tube, and connects the communication hole to the lower end of the communication hole. A valve seat and a valve body are provided on the casing, and a push-up protrusion is provided on the casing to push up the valve body and open the valve seat when the float descends.When fuel flows into the casing and the float floats, the valve body The push-up protrusion separates and the valve body closes the valve seat.In addition, when the float rises, the valve seat is closed from the upper side by the valve body, so fuel is extracted from the casing. Even if a situation occurs in which the float no longer descends after it has been removed, the rise in gas pressure within the tank body will cause the valve body to move upwards and open the valve seat, allowing the float to be moved without making the device particularly large. This has the effect of reliably preventing stickiness.

[Brief explanation of the drawing]

1.2.3 is a sectional view showing a first embodiment of the present invention, and FIG. 4 is a sectional view showing the structure of a conventional general fuel cutoff device. 2... Gas discharge hole, 3... Casing, 4... Tank body, 5... Float, 10... Communication hole, 11
...Tube, 13...Ball (valve body), 14...Valve seat, 15...Protrusion for pushing up. 2-11-η゛Suite 1 to 9 pieces L 3--1-Gauge 7 g 4----Re/Result 5-----70-to 10--171 pieces 11---Issun Yufu 13---Isshoku (person $) 14---Ha! Rev° Sheet 15---ff and rσ゛m Deputy Director Figure 3

Claims (1)

[Claims] (1) In a fuel cutoff device for a fuel tank that closes a gas discharge hole provided in the casing when fuel flows into a casing disposed at the upper part of the tank body, the casing is caused to float due to the inflow of fuel. The float is provided with a communication hole that communicates with the float in the vertical direction, and the communication hole and the gas discharge hole are connected with an expandable tube, and a valve seat is provided at the lower end of the communication hole, A fuel cutoff device for a fuel tank, characterized in that a valve element is provided for closing the valve seat from the upper side, and a pushing-up protrusion is provided on the casing to push up the valve element and open the valve seat when the float is lowered. .