JPH04185534A - Fuel shut-off device for fuel tank - Google Patents

Abstract

PURPOSE:To surely separate a float from the discharge port of gas by providing a first parmanent magnet on the front surface of the float, while providing a second permanent magnet for giving repelling force to the first parmanent magnet above a float accommodation chamber in a casing. CONSTITUTION:When a vehicle is turned or inclined, fuel flows into a casing due to fluctuation in movement of the liquid surface of fuel in a tank main body, whereby a float 8 rises with its float force and force of a spring 10 and a seal part 9 closes the discharge port of gas 5. As a result, flowing out of fuel from the part of an evaporation tube 2 never occur. When the float 8 rises, a second permanent magnet 15 rises in a gas pressure acting chamber 12 due to repelling force acting on a part between the magnets 15, 11. On the other hand, when fuel flows out of the casing 1 after the turning or inclination of vehicle is released, the float 8 is separated from the gas discharge port 5 strongly land descends due to the repelling force given to the first permanent magnet 11 by the second permanent magnet 15 and the self weight of the magnet 15.

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 speaking, this fuel cutoff device has a gas exhaust port that communicates with the evaporative tube in a casing placed in the upper part of the tank body, and also houses a float that floats when fuel flows in, preventing the vehicle from turning or tilting. When the fuel level in the tank body fluctuates and fuel flows into the casing, the float rises due to buoyancy, the seal part of the float closes the gas outlet, and the fuel passes through the evaporation tube to the outside. It is designed to prevent leakage.

However, in the case of such a fuel cutoff device, if the gas pressure inside the tank body increases with the float blocking the gas outlet due to its buoyancy, the float may separate from the gas outlet even after the fuel has flowed out of the casing. Since the so-called stick phenomenon may occur, countermeasures have been taken such as increasing the weight of the float, resulting in problems such as an increase in the weight of the vehicle.

For this reason, in the past, as a way to deal with this problem, for example, as shown in Japanese Utility Model Application No. 62-75278, a relief valve is provided in the casing, and when the float closes the gas outlet, the gas inside the tank body is A fuel cut-off device has been developed in which a relief valve opens when the pressure exceeds a set pressure, allowing 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 used to avoid the float from sticking. It is necessary to set the pressure lower than the pressure that causes strong contact with the discharge port (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 it is thought that the relief valve will open when the float normally blocks the gas outlet due to fuel flowing into the casing. Therefore, it is necessary to set the stake pressure as high as possible and this is dealt with by increasing the weight of the float, which is not a fundamental solution to the problem of increasing the size and weight of the float.

SUMMARY OF THE INVENTION Therefore, the present invention aims to provide a fuel cutoff device for a fuel tank that can reliably prevent float staking 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 gas outlet in the casing disposed in the upper part of the tank body, which communicates with the evaporative tube, and In a fuel cutoff device for a fuel tank that accommodates a float that floats and blocks the gas outlet, a first permanent magnet is provided on the upper surface of the float, and a first permanent magnet is provided in the tank body above the float accommodation chamber of the casing. A second permanent magnet was provided that was displaced downward in response to gas pressure and applied a repulsive force to the first permanent magnet.

When the gas pressure inside the tank body increases with the action float blocking the gas outlet, the second permanent magnet receives this pressure and is displaced downward, and as a result of this displacement, the second permanent magnet The repulsive force applied to the permanent magnet increases. Therefore, when the float blocks the gas exhaust port and the fuel flows out from inside the casing and the float's buoyancy no longer acts on the gas exhaust port, the float uses its own weight and the second permanent magnet that acts on the first permanent magnet. The repulsive force of the permanent magnet lowers the gas and pulls it away from the gas outlet.

Embodiments Hereinafter, first to fourth embodiments of the present invention will be described based on FIGS. 1 to 6.

First, a first example will be explained.

In Figs. 1 to 3, 1 is a casing of a fuel cutoff device made of a resin material. An evaporative tube 2 is connected to guide fuel gas to the canister. 3 is an outlet to which the evaporative tube 2 is directly connected, and this outlet 3 opens into the float storage chamber 4 in the casing 1;
This opening portion serves as a gas discharge port 5. Communication holes 6 and 7 are formed in the lower wall and side wall of the casing 1 facing the float storage chamber 4, respectively. When the fuel level in the tank body fluctuates when the vehicle turns or tilts, these communication holes 6 and 7 are formed. Then, the fuel in the tank body flows into the float storage chamber 4.

Note that S is a bracket for attaching the casing 1 to the upper part B of the tank body, and T is an intermediate tube that passes through the inside and outside of the tank body to guide evaporated fuel gas to the canister.

Reference numeral 8 denotes a float having a protruding seal portion 9 that can close the gas discharge port 5 at the center of the upper surface, and the float 8 is installed in the float storage chamber 4 with the lower surface side supported by a spring 10. The buoyant force and the force of the spring 10 close the gas outlet 5. A first permanent magnet 11 is fixedly installed on the upper surface of the float 8 .

Further, 12 is a gas pressure working chamber formed in the casing 1, and this gas pressure working chamber 12 is located above the float storage chamber 4, and its lower part is connected to the communication hole 13 on the downstream side of the gas discharge port 5. (outlet 3 side), and the upper part is electrically connected to the upper space inside the tank body through the communication hole 14. Furthermore, a second permanent magnet 15 is slidably housed inside the gas pressure action chamber 12, and the upper space and the lower space are kept airtight by this second permanent magnet 15, and the lower space has a communicating hole. Gas pressure on the evaporative tube 2 side is introduced through 13, and gas pressure inside the tank body is introduced into the upper space through a communication hole I4. Further, the second permanent magnet 15 is arranged in the gas pressure working chamber 12 so that the same poles as the first permanent magnet 11 are opposite to each other.
The repulsive force applied to the first permanent magnet 11 (the repulsive force acting on each other) gradually increases as the distance from the first permanent magnet 11 approaches.

Due to the above configuration, under normal conditions when the vehicle is not turning or tilting, the float 8 in the casing I is lowered by its own weight as shown in Figure 1, and the inside of the tank body is Communication hole 6°7, float storage chamber 4,
It communicates with the evaporative tube 2 via the gas discharge hole 5. At this time, the second permanent magnet 15 has descended a predetermined amount within the gas pressure action chamber 12 and is stopped due to a balance between the repulsive force acting between it and the first permanent magnet 11 and its own weight.

Furthermore, when the vehicle turns or leans from this position, as shown in Fig. 2, fuel flows into the casing 1 due to fluctuations in the fuel level within the tank body, and the float 8 or its buoyancy causes fuel to flow into the casing 1. The seal portion 9 is raised by the force of the spring 10 and closes the gas discharge port 5 . When the seal portion 9 closes the gas discharge port 5 in this manner, fuel no longer flows out from the evaporative tube 2 portion. Furthermore, when the float 8 rises, the second permanent magnet 15 moves into the gas pressure working chamber 1 due to the repulsive force acting between it and the first permanent magnet 11.
Rise within 2.

Here, the gas pressure inside the tank body acts on the upper surface side of the second permanent magnet 15, and the gas pressure on the evaporative tube 2 side acts on the lower surface side, so when the gas pressure inside the tank body increases, the second permanent magnet 15 As shown in Figure 3, the pressure difference generated between the upper and lower surfaces causes it to be displaced downward. When the second permanent magnet 15 is thus displaced downward, the second permanent magnet 15
The repulsive force that is applied to the first permanent magnet 11, that is, the force that tries to push the float 8 downward gradually increases. However, while the fuel is flowing into the casing 1, the buoyancy is acting as a force to lift the float 8 upward, so the gas outlet 5 remains blocked by the float 8. .

When the turning or tilting of the vehicle is released from this state and the fuel flows out from the casing 1, the buoyancy of the float 8 disappears, so the float 8 absorbs the reaction force that the second permanent magnet 15 gives to the first permanent magnet 11. Then, due to its own weight, it is strongly pulled away from the gas discharge [ ] 5 and returns to its original state.

In this way, when fuel flows out from the casing 1, not only its own weight but also the gas pressure within the tank body acts on the float 8 (via the repulsive force of the permanent magnets 15, 11). Even if the gas pressure inside the tank body increases with the gas outlet 5 blocked, the float 11
staking will no longer occur.

Next, second to fourth embodiments of the present invention will be described.

FIG. 4 shows a second embodiment of the present invention. In the case of this fuel cutoff device, a spring 16 is provided inside the gas pressure action chamber 12 to elastically support the second permanent magnet 15. It differs from the first embodiment in that it is accommodated. This fuel cutoff device has a structure in which the spring 16 elastically supports the second permanent magnet 15, so it is less susceptible to the repulsive force of the float 8 or the permanent magnet 1.1.1.5 that rises due to buoyancy. Become.

FIG. 5 shows a third embodiment of the present invention. In the case of this fuel cutoff device, a resin diaphragm 17 is provided on the upper wall of the gas pressure working chamber 12, and a second permanent magnet 15 is attached to the resin diaphragm 17. This embodiment differs from the second embodiment in that it is supported by a diaphragm 17 and that the gas pressure chamber 12 is provided in series in the middle of the passage from the gas discharge port 5 of the casing 1 to the outlet 3. In this fuel cutoff device, the diaphragm 17 allows vertical displacement of the second permanent magnet 15 while maintaining the inside and outside of the gas pressure working chamber 12 in a sealed state. It supports elastically due to its flexural deformation characteristics. Therefore, when the gas pressure inside the tank body increases with the float 8 blocking the gas outlet 5, the center of the diaphragm 17 moves downward together with the second permanent magnet 15, and the second permanent magnet 15 The repulsive force applied to the first permanent magnet 11 increases.

Further, FIG. 6 shows a fourth embodiment of the present invention,
This fuel cutoff device is different from the third embodiment in that a membrane-like rubber material 18 is attached to the earthen wall of the gas pressure action chamber 12, and the second permanent magnet 15 is supported by this rubber material 18. different from. This fuel cutoff device functions almost the same as that of the third embodiment, but instead of using the bending of the resin material, it uses the elongation of the rubber material 18 to elastically move the second permanent magnet 15. I support it.

Effects of the Invention As described above, the present invention provides the first permanent magnet on the upper surface of the float, and the first permanent magnet is disposed above the float accommodation chamber of the casing and is displaced downward in response to the gas pressure within the tank body. A second permanent magnet is provided that applies a repulsive force to the permanent magnet, and the second permanent magnet applies not only its own weight but also the repulsive force that the second permanent magnet applies to the first permanent magnet against the float with the gas discharge port blocked. Since the gas pressure inside the tank body acts through the casing, the float can be reliably pulled away from the gas outlet when the buoyancy of the float no longer acts due to the flow of fuel from the casing. As a result, it becomes possible to reliably prevent the float from sticking without increasing the size of the device.

[Brief explanation of drawings]

1.2.3 is a sectional view showing the first embodiment of the present invention, FIG. 4 is a sectional view showing the second embodiment of the invention, and FIG. 5 is a sectional view showing the third embodiment of the invention. 6 are sectional views showing a fourth embodiment of the present invention. 1...Casing, 2...Evapo tube, 4...
- Float storage chamber, 5... Gas discharge port, 8... Float, 11... First permanent magnet, 15... Second permanent magnet. of

Claims (1)

[Claims] (1) In the casing located at the top inside the tank body,
In addition to providing a gas exhaust port that communicates with the evaporative tube,
A fuel cut-off device for a fuel tank that houses a float that floats due to inflow of fuel and blocks the gas outlet,
A first permanent magnet is provided on the upper surface of the float, and a first permanent magnet is disposed above the float housing chamber of the casing and is displaced downward in response to gas pressure within the tank body to apply a repulsive force to the first permanent magnet. A fuel cutoff device for a fuel tank, characterized in that it is provided with two permanent magnets.