JPH04201720A - Fuel cut-off of fuel tank - Google Patents

Abstract

PURPOSE:To surely prevent sticking of a float without enlarging the size of a device which comprises the float for floating and blocking a gas discharging hole by fuel inflow by providing both orifices for gas incoming and outgoing, and for fuel incoming and outgoing on the float. CONSTITUTION:This fuel cut-off has on its upper end a casing provided with an outlet 3 for discharging evaporated fuel gas generated in a tank main body. Through holes 6, 7 are respectively formed in the lower wall and the side wall of the casing 1 wherein its inside space is used as a float storing room 4, and a float 8 which is provided with a seal portion 9 capable of blocking a gas discharging hole 5 is stored in the float storing room 4. A hollow portion 11 is formed in this float 8, and it is communicated to the outer surface of the float 8 by an orifice 12 for fuel incoming and outgoing, and by an orifice 13 for gas incoming and outgoing. Thereby, when fuel flows out from the casing 1, the float 8 is to be surely separated from the gas discharging hole due to action of a weight of fuel in the hollow portion 11 to the float 8.

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.

Conventional technology Some fuel tanks for automobiles may
It is known that a fuel cutoff device is installed to prevent the fuel inside the tank body from leaking to the outside. Generally, this fuel cutoff device has a gas exhaust hole 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. When the fuel level in the tank body fluctuates and fuel flows into the casing, the float rises and the seal part of the float closes the gas discharge hole.
This prevents fuel from flowing outside through the evaporative tube.

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 exhaust hole due to buoyancy, the float will continue to flow through the gas exhaust hole even after the fuel has flowed out of the casing. Since it is possible that the so-called sticking phenomenon occurs, in which the float becomes stuck, the weight of the float is increased, which causes problems such as an increase in the weight of the vehicle.

For this reason, in the past, as a solution to 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 discharge hole, the gas inside the tank body is A fuel cutoff device has been developed in which a relief valve opens when the pressure exceeds a set pressure, allowing the gas in the tank body to escape to the evaporative tube, thereby avoiding a 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 sticking of the float. Pressure that causes strong contact with the discharge hole (hereinafter referred to as stick pressure)
It needs to be set lower than . 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 exhaust hole due to fuel flowing into the casing. Therefore, the need to set the stake pressure as high as possible has been dealt with by increasing the weight of the float, and this is not a fundamental solution to the increase in float size and weight.

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 exhaust hole that communicates with the evaporative tube in the casing disposed in the upper part of the tank body, and also In a fuel cutoff device for a fuel tank that accommodates a float that floats and blocks the gas discharge hole, the float is provided with a hollow part, and the float is further provided with a fuel inlet/outlet orifice that communicates the hollow part with an outer surface of the float, and a gas inlet/outlet. An orifice was provided for use.

When the fuel level inside the tank body fluctuates and fuel flows into the casing, the gas in the hollow part escapes from the gas inlet/outlet orifice, and fuel gradually flows into the float's hollow part from the fuel inlet/outlet orifice. At the same time, the float rises and closes the gas exhaust hole. In addition, if the fuel level inside the tank body returns to its original level from this state and fuel flows out from inside the casing, the fuel inside the hollow part will not immediately escape from the fuel inlet/outlet orifice to the outside of the float, so the float will not be able to handle its own weight. In addition, the weight of the fuel in the hollow will act, and the float will be moved away from the gas outlet.

EXAMPLE Hereinafter, an example of the present invention will be described based on FIGS. 1 to 3.

In Figs. 1 to 3, 1 is a casing of a fuel cutoff device made of a resin material. Canister for evaporated fuel gas
An evaporative tube 2 is connected. Further, reference numeral 3 denotes an outlet to which the evaporative tube 2 is directly connected, and the base of the outlet 3 opens into the float storage chamber 4 in the casing 1, and this opening portion serves as a gas discharge hole 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 due to the inclination of the vehicle, etc., the communication holes 6 and 7 can be opened. Then, the fuel in the tank body flows into the float storage chamber 4.

Reference numeral 8 denotes a float having a sealing portion 9 in the center of its upper surface that can close the gas discharge hole 5, and this float 8 is supported by a spring 10 on the lower surface thereof and is inserted into the float storage chamber 4.
is installed inside. In addition, the float 8 has a hollow part 11.
The hollow portion 11 communicates with the outer surface of the float 8 through a fuel inlet/outlet orifice 12 formed on the lower wall side and a gas inlet/outlet orifice 13 formed on the upper wall side. On the other hand, on the lower surface of the upper wall of the casing 1, there is an orifice 13 for gas inlet and outlet of the float 8.
A protrusion 14 that can be fitted into the float 8 is formed so that when the float 8 rises due to buoyancy, the passage of the gas inlet/outlet orifice 13 is completely blocked or narrowed by the protrusion 14.

In the above configuration, when the fuel liquid level in the tank body fluctuates due to the inclination of the vehicle and the fuel flows into the float storage chamber 4 of the casing 1, the fuel flows into the hollow part 11 of the float 8 through the fuel inlet/outlet orifice 12. As the water gradually flows in, the float 8 rises due to its buoyancy and the force of the spring 10. When fuel flows into the hollow part 11 of the float 8, the gas in the hollow part 11 flows through the gas inlet and outlet orifice 1.
3 and exits to the outside of the float 8. When the float 8 rises by the set amount in this way, the seal portion 9 of the float 8 closes the gas discharge hole 5 of the caning 1, and the gas inlet/outlet orifice 13 is narrowed by the protrusion 14, or
It becomes completely occluded.

In addition, when the fuel level in the tank body returns to its original level from this state and the fuel in the casing 1 flows out through the communication hole 6, the fuel that once entered the hollow part 11 of the float 8 flows through the fuel inlet/outlet orifice 12. It tries to come out, but it doesn't come out all of a sudden, so the float 8 pushes the casing 1 due to its own weight and the weight of the fuel remaining in the hollow part 11.
It will be strongly pulled away from the gas discharge hole 5. Therefore, even if the gas pressure within the tank body increases with the float 8 blocking the gas discharge hole 5 due to its buoyancy, the float 8 will not stag.

Effects of the Invention As described above, the present invention provides a hollow part in a float, and further provides a fuel inlet/outlet orifice and a gas inlet/outlet orifice in the float that communicate the hollow part with the outer surface of the float, so that the float can be used for fuel inlet/output when the float is rising. Since the fuel that has flowed into the hollow part from the orifice is not drawn out immediately, when the fuel flows out from inside the casing, not only its own weight but also the weight of the fuel in the hollow part acts on the float, causing the float to close the gas discharge hole. You will definitely be separated from them. As a result, it becomes possible to reliably prevent the float from sticking without increasing the size of the device.

[Brief explanation of the drawing]

Figures 1.2.3 are sectional views showing one embodiment of the present invention. ■...Casing, 2...Evapo tube, 5...
・Gas exhaust hole, tail...float, 11...hollow part, 1
2... Orifice for fuel inlet/output, 13... Orifice for gas inlet/output. I...Casing 2...Evapor tube 5, Gas discharge hole 8, Float 11...Hollow part I2...Fuel inlet and outlet orifice 13...Gas inlet and outlet orifice

Claims (1)

[Claims] (1) In the casing located at the top inside the tank body,
In addition to providing a gas exhaust hole that communicates with the evaporation tube,
A fuel cutoff device for a fuel tank that houses a float that floats due to inflow of fuel and blocks the gas discharge hole,
A fuel cutoff device for a fuel tank, characterized in that the float is provided with a hollow section, and the float is further provided with a fuel inlet/outlet orifice and a gas inlet/outlet orifice that communicate the hollow section with the outer surface of the float.